WO2025062774A1 - Ink supply device, ink supply method, and inkjet printer - Google Patents

Abstract

The present invention accurately detects an ink residual amount in a tank for storing ink in an ink supply device with a simple configuration having a low maintenance cost. A tank support mechanism (330) configured to rotate in accordance with the weight of an ink tank (32) by using a plate-like member (331) that can rotate around a rotation shaft (331a) and an elastic member (332) is provided on a base-like portion (31a) of a body (31) of an ink supply device 30 of an inkjet printing device. A label (51) of a QR code (registered trademark) in which ink information is recorded is attached to a back surface (32B) of the ink tank (32). In a control unit (100), image analysis is performed using imaging data obtained with a camera (41) for imaging the label (51). The inclination of the ink tank (32) is determined, for example, on the basis of the interval between the upper side and the lower side of the label (51) in the captured image, and the remaining amount of ink in the ink tank (32) is determined from the inclination.

Description

INK SUPPLY DEVICE, INK SUPPLY METHOD, AND INKJET PRINTING DEVICE

The present invention relates to an ink supply device and an inkjet printing device equipped with the same, and more specifically to detection of the amount of ink remaining in an ink tank that stores ink in the ink supply device.

In an inkjet printing device, an image is formed on a recording medium, such as a long sheet of printing paper, by ejecting ink onto the recording medium. C (cyan), M (magenta), Y (yellow), and K (black) inks are usually used as the inks ejected onto the recording medium. For example, in a commercial inkjet printing device, an ink supply device that supplies each of these C, M, Y, and K inks is provided separately from the main printing device body. The ink supply device includes tanks (also called "main tanks") that store the C, M, Y, and K inks, and pumps for moving the C, M, Y, and K inks, and the amount of ink remaining in each tank is detected while the inkjet printing device is in operation.

In such a configuration, the amount of ink remaining in each tank can be detected, for example, by calculating the amount based on the driving time of a pump for moving the ink in the tank, or by using a float to detect the ink level in the tank. Also known are methods of optically detecting the position of the ink level in the tank by using the blocking, transmission, or refraction of light from a light source, and methods of capturing an image of the ink level with an imaging device (see, for example, JP 2008-200955 A and JP 2020-19243 A).

Japanese Patent Application Publication No. 2008-200955 Japanese Patent Application Publication No. 2020-19243 Japanese Patent Application Publication No. 2020-49660

Among the above conventional methods for detecting the remaining amount of ink in a tank (hereafter referred to as an "ink tank") that stores ink used in inkjet printing devices, the method of calculating the remaining ink amount from the operating time of the pump does not necessarily provide sufficient accuracy in detecting the remaining ink amount because the pump's liquid delivery capacity varies depending on the pump start-up time and deterioration over time. Also, the method of detecting the ink level in an ink tank using a float has problems with the durability of the float and the need for regular cleaning. Furthermore, the method of detecting the ink level using a float, the method of optically detecting the ink level, and the method of imaging the ink level require a dedicated configuration to implement these methods.

Therefore, it is desirable to accurately detect the remaining amount of ink in a tank that stores ink in an ink supply device using a simple configuration with low maintenance costs.

A first aspect of the present invention is an ink supply device, comprising:
A tank for storing ink;
a support mechanism that supports the tank such that a vertical position or an inclination of the tank changes according to a weight of the tank, the support mechanism including an elastic member that supports a bottom surface of the tank;
an imaging unit that images the tank and generates imaging data showing at least a portion of the tank;
an image analysis unit that determines the vertical position or the inclination based on the imaging data;
and a remaining ink amount determination unit that determines the remaining amount of ink in the tank based on the vertical position or the inclination determined by the image analysis unit.

A second aspect of the present invention relates to a method for producing a composition according to the first aspect of the present invention,
The tank has a front surface, a back surface and two sides;
the support mechanism is configured to support the tank such that lower sides of the two side surfaces are inclined relative to a horizontal direction in response to a weight of the tank,
the imaging unit is disposed at a position capable of imaging one of the front surface, the back surface, and the two side surfaces,
the image analysis unit extracts a specific pattern in an image represented by the imaging data based on the imaging data, and determines the inclination based on the extracted specific pattern;
The remaining ink amount determination unit determines the remaining ink amount based on the slope determined by the image analysis unit.

A third aspect of the present invention relates to a method for producing a composition according to the second aspect of the present invention,
the imaging unit is disposed at a position capable of imaging one of the front surface and the back surface,
a label attached to said one surface;
the specific pattern is two linear patterns indicating the upper and lower ends of the label,
The image analysis unit obtains a distance between the two linear patterns in an image represented by the imaging data, and obtains the inclination based on the distance.

A fourth aspect of the present invention is a method for producing a composition according to the second aspect of the present invention, comprising:
the imaging unit is disposed at a position capable of imaging one of the two side surfaces,
the specific pattern is a linear pattern indicating a lower side of the one surface,
The image analysis unit determines, as the inclination, an angle that the linear pattern makes with respect to a horizontal direction in the image represented by the imaging data.

A fifth aspect of the present invention relates to a method for producing a composition according to the second aspect of the present invention,
the imaging unit is disposed at a position capable of imaging one of the front surface and the back surface,
a mark including two indicators spaced apart in a vertical direction is provided on one of the front surface and the back surface;
the specific pattern is a pattern indicating the two indicators,
The image analysis unit obtains a distance between the two indices in an image represented by the imaging data, and obtains the inclination based on the distance.

A sixth aspect of the present invention is a method for producing a composition according to the first aspect of the present invention, comprising:
the support mechanism supports the tank such that the tank does not tilt and the vertical position of the tank changes in response to the weight of the tank,
The tank has a front surface, a back surface and two sides;
the imaging unit is disposed at a position capable of imaging one of the front surface, the back surface, and the two side surfaces,
The image analysis unit extracts a specific pattern in an image represented by the imaging data based on the imaging data, and determines a vertical position of the extracted specific pattern;
The remaining ink amount determination unit determines the remaining ink amount based on the vertical position of the specific pattern determined by the image analysis unit.

A seventh aspect of the present invention is a method for producing a composition according to the sixth aspect of the present invention, comprising:
The specific pattern is a linear pattern indicating the upper side or the lower side of the one surface.

An eighth aspect of the present invention is a method for producing a composition according to the sixth aspect of the present invention, comprising:
a label attached to said one surface;
The specific pattern is a linear pattern indicating the top or bottom edge of the label.

A ninth aspect of the present invention is a method for producing a composition according to the sixth aspect of the present invention, comprising:
A mark including an index is provided on the one surface,
the specific pattern is a pattern indicating the index,
The image analysis unit determines a vertical position of the index in the image represented by the imaging data,
The remaining ink amount determination unit determines the remaining ink amount based on the vertical position of the indicator determined by the image analysis unit.

A tenth aspect of the present invention relates to a method for producing a composition comprising the steps of:
the label is a label including a QR code (registered trademark) for recording ink information;
The image analysis unit acquires the ink information from the imaging data.

An eleventh aspect of the present invention is a method for producing a composition according to the fifth or ninth aspect of the present invention, comprising:
the mark is a QR code that records ink information related to the ink stored in the tank to which the mark is attached,
The image analysis unit acquires the ink information from the imaging data.

A twelfth aspect of the present invention is an inkjet printing apparatus comprising:
A conveying mechanism for conveying a long recording medium;
a recording head that ejects ink onto the recording medium;
a print execution control unit that controls the recording head and the transport mechanism so that a print image is formed on the recording medium;
and an ink supply device according to any one of the first to eighth aspects, which supplies ink to be ejected by the recording head.

A thirteenth aspect of the present invention is an ink supplying method for supplying ink from a tank that stores ink in an ink supplying device, the method comprising the steps of:
an ink remaining amount detection step for detecting the amount of ink remaining in the tank;
The ink supply device includes:
a support mechanism that supports the tank such that a vertical position or an inclination of the tank changes according to a weight of the tank, the support mechanism including an elastic member that supports a bottom surface of the tank;
an imaging unit that images the tank,
The ink remaining amount detection step includes:
an imaging step of imaging the tank by the imaging unit and generating imaging data showing at least a portion of the tank;
an image analysis step of determining the vertical position or the inclination based on the imaging data;
and determining the amount of ink remaining in the tank based on the vertical position or the inclination determined by the image analysis step.

Other aspects of the present invention are apparent from the above aspects of the present invention and the description of the embodiments and their variations below, and therefore will not be described here.

In a first aspect of the present invention, a tank support mechanism that supports a tank that stores ink is configured so that the vertical position or inclination of the tank changes depending on the weight of the tank, and the vertical position or inclination of the tank is found by an image analysis unit based on imaging data of the tank, and the amount of ink remaining in the ink tank is determined based on the found vertical position or inclination. This requires less maintenance costs than a configuration that uses a float to detect the amount of ink remaining, and provides higher accuracy in detecting the amount of ink remaining than a configuration that calculates the amount of ink remaining based on the operating time of a pump that supplies ink. In this way, according to the first aspect of the present invention, the amount of ink remaining in a tank that stores ink in an ink supply device is accurately detected with a simple configuration that requires less maintenance costs. In addition, in the case where a label including a QR code that records ink information is attached to the outer surface of a tank and an imaging unit that images the label to obtain the ink information is already provided in the ink supply device as in the tenth aspect of the present invention, or in the case where a QR code that records ink information is attached to a tank and an imaging unit that images the QR code to obtain the ink information is already provided in the ink supply device as in the eleventh aspect of the present invention, the remaining ink level can be detected simply by adding software for image analysis based on the imaging data of the imaging unit. This allows the remaining ink level to be detected at a lower cost.

In the second to twelfth aspects of the present invention, the same effects as in the first aspect of the present invention can be obtained. In addition, in the fourth and sixth to ninth aspects of the present invention, the following unique effects can be obtained.

In other words, in the fourth aspect of the present invention, an imaging unit is positioned so as to be able to image the side of a tank attached to a tank support mechanism, and in an image represented by imaging data generated by the imaging unit, a linear pattern indicating the bottom edge of the side is extracted as a specific pattern, and the angle that the linear pattern makes with the horizontal direction is found as the inclination of the tank. In this way, the inclination of the tank can be directly found based on imaging data obtained by imaging the tank from the side, and the remaining ink level can be detected with greater accuracy than in the second and third aspects of the present invention.

In addition, in the sixth to ninth aspects of the present invention, the tank support mechanism that supports the tank that stores ink is configured so that the vertical position of the tank can be changed according to the weight of the tank without tilting the tank. Therefore, even if the tank has a large capacity, ink can be supplied to the printing mechanism stably and safely while detecting the remaining ink amount, compared to the first to fifth aspects of the present invention.

The effects of other aspects of the present invention are clear from the explanation of the effects of the above aspects of the present invention and the effects of the following embodiment and its modified examples, so a detailed explanation will be omitted.

1 is a schematic diagram illustrating a configuration of an inkjet printing apparatus according to a first embodiment of the present invention. FIG. 2 is a perspective view illustrating an ink supply mechanism according to the first embodiment. FIG. 2 is a diagram showing a configuration of an ink supply device in the first embodiment. FIG. 2 is a block diagram showing a hardware configuration of a control unit in the first embodiment. FIG. 2 is a block diagram showing a functional configuration of a control unit in the first embodiment. 5A to 5C are diagrams for explaining a configuration for detecting the remaining amount of ink in the first embodiment. 5A to 5C are diagrams showing a state of the ink supply device when a large amount of ink remains in the first embodiment. 5A to 5C are diagrams showing a state of the ink supply device when the remaining amount of ink is small in the first embodiment. 6 is a flowchart showing an example of a remaining ink amount detection process in the first embodiment. 10 is a flowchart showing another example of the remaining ink amount detection process in the first embodiment. 10A to 10C are diagrams for explaining image analysis in another example of the remaining ink amount detection process in the first embodiment. 13 is a diagram for explaining a configuration for detecting the remaining amount of ink in an ink supply device according to a modified example of the first embodiment. FIG. 13A to 13C are diagrams showing captured images obtained in the modified example of the first embodiment. 10 is a flowchart showing an example of a remaining ink amount detection process in a modified example of the first embodiment. FIG. 11 is a diagram for explaining a configuration for detecting the remaining amount of ink in an inkjet printing apparatus according to a second embodiment of the present invention. 13A and 13B are diagrams illustrating a state of the ink supply device when a large amount of ink remains in the second embodiment. 13A and 13B are diagrams illustrating a state of the ink supply device when the remaining amount of ink is small in the second embodiment. 13 is a flowchart showing a first example of a process for detecting the remaining ink level in the second embodiment. 13 is a flowchart showing a second example of the remaining ink amount detection process in the second embodiment. 13 is a flowchart showing a third example of the remaining ink amount detection process in the second embodiment. 5A to 5C are diagrams for explaining advantages and disadvantages of the configuration for detecting the amount of remaining ink in the first embodiment in comparison with other configurations for detecting the amount of remaining ink. 13A to 13C are diagrams for explaining advantages and disadvantages of the configuration for detecting the amount of remaining ink in the second embodiment in comparison with other configurations for detecting the amount of remaining ink. 13A to 13C are diagrams for explaining advantages and disadvantages of the configuration for detecting the amount of remaining ink in the modified example of the first embodiment, in comparison with other configurations for detecting the amount of remaining ink.

Below, an embodiment of the present invention will be described with reference to the attached drawings.

1. First embodiment
<1.1 Overall configuration>
1 is a schematic diagram showing the configuration of an inkjet printing device 10 according to a first embodiment of the present invention. The printing device 10 includes a paper delivery section 202 that unwinds and supplies recording paper (hereinafter, also simply referred to as "paper") 5 as a long continuous recording medium from a roll of paper as a roll-shaped recording medium, a first drive roller 203 for transporting the paper 5 into the inside of a printing mechanism 200, a plurality of support rollers 204 for transporting the paper 5 inside the printing mechanism 200, a recording section 205 that ejects ink onto the paper 5 to perform printing, an ink supply mechanism 300 that supplies ink to the recording section 205, a second drive roller 207 for outputting the paper 5 from inside the printing mechanism 200, and a paper winding section 208 that winds up the paper 5 after printing. The first drive roller 203, the support roller 204, and the second drive roller 207 form a transport mechanism for moving the paper 5. The recording unit 205 includes first to fourth recording heads 20C, 20M, 20Y, and 20K that eject C (cyan), M (magenta), Y (yellow), and K (black) inks, respectively, and first to fourth sub-tanks 22C, 22M, 22Y, and 22K that store the C, M, Y, and K inks before ejection, respectively, and the first to fourth recording heads 20C, 20M, 20Y, and 20K are connected to the first to fourth sub-tanks 22C, 22M, 22Y, and 22K by piping, respectively. The ink supply mechanism 300 includes first to fourth ink supply devices 30C, 30M, 30Y, and 30K that supply C, M, Y, and K inks, respectively. The ink supplied from each ink supply device 30X is temporarily stored in a sub-tank 22X (X=C, M, Y, K) in the printing mechanism 200. Each recording head 20X ejects the ink stored in the sub-tank 22X (X=C, M, Y, K) according to the image to be printed, thereby forming the image as a color print image on the paper 5. This inkjet printing device 10 further includes a control unit 100 that controls each part of the printing mechanism 200 and the ink supply mechanism 300. Details of the control unit 100 will be described later.

Conventionally, there has been known an ink supply mechanism in which a label containing a QR code (registered trademark) recording ink information such as the composition of the ink stored in an ink tank (main tank), manufacturing date, color, model number, etc. is affixed to the ink tank, and the QR code is read by a camera to obtain the ink information. In this embodiment, the ink supply mechanism 300 also has such a configuration. Figure 2 is a perspective view that shows a schematic diagram of the ink supply mechanism 300 in this embodiment. The main body 31 of this ink supply mechanism 300 consists of a platform portion 31a having a horizontal upper surface and a wall portion 31b having a vertical front surface. As described above, the ink supply mechanism 300 includes the first to fourth ink supply devices 30C, 30M, 30Y, and 30K, and the first to fourth ink tanks 32 that store the C, M, Y, and K inks, respectively, are mounted on the platform portion 31a in the first to fourth ink supply devices 30C, 30M, 30Y, and 30K, and a tank support mechanism for this purpose is provided on the platform portion 31a (described in detail later). A QR code label recording ink information is affixed to the surface facing the front surface of the wall portion 31b of the main body 31, i.e., the back surface, of the outer surface of each ink tank, and a camera 41 for reading the QR code is built into the wall portion 31b.

1.2 Ink supply device
In the ink supply mechanism 300 of this embodiment, the first to fourth ink supply devices 30C, 30M, 30Y, and 30K that supply C, M, Y, and K inks, respectively, have the same configuration and operate in the same manner, except for the color of ink they supply. Therefore, the following will focus on one of these four ink supply devices 30C, 30M, 30Y, and 30K and explain its configuration and operation (hereinafter, the ink supply device of interest will be designated by the reference symbol "30").

FIG. 3 is a block diagram showing the configuration of the ink supply device 30. The ink supply device 30 includes an ink tank 32, a tank support mechanism 330, a camera 41, a first liquid supply pipe 62, an intermediate tank 33, and a second liquid supply pipe 64. The ink tank 32 is also called the main tank. In the following, the upstream side of the ink supply path will be simply called the "upstream side", and the downstream side of the ink supply path will be simply called the "downstream side".

The tank support mechanism 330 is a base for supporting the ink tank 32 as an ink supply source, and is configured so that the ink tank 32 tilts (the bottom surface of the ink tank 32 tilts relative to the horizontal) according to the amount of ink stored in the ink tank 32 (hereinafter also referred to as the "remaining ink amount"), i.e., according to the weight of the ink tank 32. The ink tank 32 is a rectangular container, and a QR code (registered trademark) label 51 is attached to the back surface 32B of the ink tank 32 as a two-dimensional barcode that records ink information such as the ink ingredients, manufacturing date, color, and model number. The camera 41 is an imaging unit provided to read this QR code. Unused ink is stored in the ink tank 32. The initial amount of ink stored in the ink tank 32 is, for example, approximately 200 liters at most.

The first liquid supply pipe 62 is a pipe for supplying ink from the ink tank 32 to the intermediate tank 33. As shown in FIG. 3, the first liquid supply pipe 62 has a suction pipe 321, a curved pipe 324, a descending pipe 322, and a main pipe 323. The suction pipe 321 sends the ink inside the ink tank 32 in an upward direction. The curved pipe 324 is connected to the downstream end (upper end) of the suction pipe 321, and changes the ink sending direction to a downward direction. The descending pipe 322 sends the ink in a downward direction. The downstream end (lower end) of the descending pipe 322 is connected to the main pipe 323, which sends the ink from the descending pipe 322 to the intermediate tank 33.

The suction pipe 321 is a pipe for sucking up ink from inside the ink tank 32. The suction pipe 321 has a suction port at its upstream end (lower end), which is located near the bottom surface inside the ink tank 32. Specifically, the upstream end of the suction pipe 321 is abutted against the bottom surface inside the ink tank 32, and this end has a suction port that opens at an angle to the bottom surface of the ink tank 32.

The descending pipe 322 is a pipe located downstream of the curved pipe 324. The height of the descending pipe 322 gradually decreases toward the downstream side. In this embodiment, the descending pipe 322 extends downward along the vertical direction.

The main pipe 323 is a pipe that connects the downstream end of the descending pipe 232 and the intermediate tank 33. An electromagnetic valve 305 and a first pump 301 are inserted near the upstream end of the main pipe 323. The electromagnetic valve 305 switches between a closed state in which the flow path in the pipe is closed and an open state in which the flow path in the pipe is open according to a control signal from the control unit 100. The first pump 301 creates a flow of ink in the first liquid supply pipe 62 toward the downstream side. When the first pump 301 is operated with the electromagnetic valve 305 in the open state, ink is supplied from the ink tank 32 through the suction pipe 321, the descending pipe 322, and the main pipe 323 to the intermediate tank 33.

The intermediate tank 33 is a tank that stores ink between the first liquid supply pipe 62 and the second liquid supply pipe 64. The capacity of the intermediate tank 33 is smaller than the capacity of the ink tank 32. For example, it is a maximum of about 20 liters. The downstream end of the main pipe 323 is located inside the intermediate tank 33. The intermediate tank 33 temporarily stores ink and acts as a buffer to prevent ink shortage downstream of the intermediate tank 33.

First and second liquid level sensors (not shown) are provided near the outside of the wall surface of the intermediate tank 33. The first liquid level sensor 231 is a sensor that detects the presence or absence of ink at a predetermined lower limit position of the intermediate tank 23. The control unit 100 determines whether the amount of ink stored in the intermediate tank 33 is within an acceptable range based on the detection results of the first and second liquid level sensors.

The second liquid supply pipe 64 is a pipe that connects the intermediate tank 33 and the subtank 22 (the subtank connected to the ink supply device 30 of interest among the subtanks 22C, 22M, 22Y, and 22K) in the printing mechanism 200. The upstream end of the second liquid supply pipe 24 is located near the bottom surface of the intermediate tank 33. The downstream end of the second liquid supply pipe 64 is connected to the subtank 22. In addition, a second pump 302 is interposed on the path of the second liquid supply pipe 64. The second pump 302 forms a flow of ink in the second liquid supply pipe 64 toward the downstream side. When the second pump 302 is driven, the ink stored in the intermediate tank 33 is supplied to the subtank 22 through the second liquid supply pipe 64.

<1.3 Configuration of the control unit>
4 is a block diagram showing the hardware configuration of the control unit 100 in this embodiment. The control unit 100 includes a main body 11, an auxiliary storage device 12, a display unit 14, and an operation unit 15. The main body 11 includes a CPU 111, a memory 112, a disk interface unit 113, a display control unit 115, an input interface unit 116, a print execution control interface unit 117, an ink supply control interface unit 118, an image capture interface unit 119, and a network interface unit 120. The CPU 111, the memory 112, the disk interface unit 113, the display control unit 115, the input interface unit 116, the print execution control interface unit 117, the ink supply control interface unit 118, the image capture interface unit 119, and the network interface unit 120 are connected to each other via a system bus. The auxiliary storage device 12 is connected to the disk interface unit 113. The display unit 14 is connected to the display control unit 115. The operation unit 15 including a keyboard, a mouse, etc. is connected to the input interface unit 116. A network 3 is connected to the network interface unit 120, and the control unit 100 is connected to a host device or the like via this network 3. The auxiliary storage device 12 is a magnetic disk device or the like. The display unit 14 is a liquid crystal display or the like. The display unit 14 is used to display information desired by an operator. The operation unit 15 is used to input instruction operation information Iop that indicates instructions from the operator to the inkjet printing apparatus 10.

The auxiliary storage device 12 stores a print control program 17 for generating print data from submitted data received via the network 3 and for causing the print mechanism 200 to print an image represented by the print data. This print control program includes an ink supply control program for controlling the supply of ink to the print mechanism 200, and an ink remaining amount detection program for detecting the amount of ink remaining in the ink tanks 32 in each of the ink supply devices 30C, 30M, 30Y, and 30K that supply the ink.

The CPU 111 reads the print control program 17 stored in the auxiliary storage device 12 into the memory 112 and executes it to realize various functions of the inkjet printing device 10. The memory 112 includes a RAM (Random Access Memory) and a ROM (Read Only Memory). The memory 112 functions as a work area for the CPU 111 to execute the print control program 17.

The print execution control interface unit 117 functions as an interface for the CPU 111 executing the print control program to control each part of the print mechanism 200. The image capture interface unit 119 functions as an interface for the CPU 111 executing the print control program to receive image capture data obtained by the camera 41 in each ink supply device 30C, 30M, 30Y, 30K capturing an image of the QR code or the like in the ink tank 32.

FIG. 5 is a block diagram showing the functional configuration of the main functions of the control unit 100 in this embodiment. When the CPU 111 executes the print control program 17 as described above, the control unit 100 having the functional configuration shown in FIG. 5 is realized. As shown in FIG. 5, this control unit 100 functionally includes a print execution control unit 150, an ink supply control unit 152, an image analysis unit 162, and an ink remaining amount determination unit 164, and the image analysis unit 162 and the ink remaining amount determination unit 164 constitute the ink remaining amount detection processing unit 160.

The print execution control unit 150 outputs control signals (hereinafter referred to as "print execution control signals") for controlling the recording heads 20C, 20M, 20Y, 20K and the drive rollers 203, 207 in the transport mechanism, etc., in response to instruction operation information Iop input based on the operator's operation on the operation unit 15. The ink supply control unit 152 receives information relating to the control of the recording heads 20C, 20M, 20Y, 20K from the print execution control unit 110, and based on this, outputs control signals (hereinafter referred to as "ink supply control signals") for controlling the pumps 301, 302 and solenoid valves 305 in each ink supply device 30C, 30M, 30Y, 30K. Based on the print execution control signal, the recording heads 20C, 20M, 20Y, and 20K and the drive rollers 203 and 207 in the printing mechanism 200 operate, and based on the ink supply control signal, the pumps 301 and 302 and the solenoid valves 305 in the ink supply devices 30C, 30M, 30Y, and 30K operate, causing ink to be ejected from each recording head 20C, 20M, 20Y, and 20K onto the transferred paper 5, and a color image based on the instruction operation information Iop is formed on the paper 5 as a print image.

In parallel with controlling the printing mechanism 200 and ink supply mechanism 300 (ink supply devices 30C, 30M, 30Y, 30K), the ink remaining amount detection processing unit 160 receives image data Dim obtained by capturing images of the QR code labels 51 and the like using the cameras 41 in each of the ink supply devices 30C, 30M, 30Y, 30K. In the ink remaining amount detection processing unit 160, the image analysis unit 162 performs image analysis, described below, on the image represented by this image data Dim, and the ink remaining amount determination unit 164 determines the amount of ink remaining in the ink tank 32 based on the results of the image analysis. The amount of ink remaining determined in this manner is sent to the print execution control unit 150.

When the print execution control unit 150 receives the remaining ink amount from the remaining ink amount determination unit 164, it controls the display unit 14, the printing mechanism 200, and/or the ink supply mechanism 300 based on that remaining ink amount. For example, it displays the remaining ink amount on the display unit 14 in response to instruction operation information Iop that instructs the display of the remaining ink amount, and if the remaining ink amount is below a predetermined amount, it displays warning information or information urging the user to replenish ink on the display unit 14, or stops the operation of the printing mechanism 200 and the ink supply mechanism 300.

The camera 41 is originally provided to read the QR code in the ink tank 32 and obtain ink information (such as ink composition, manufacturing date, color, and model number). For this reason, the image analysis unit 162 has the function of receiving imaging data Dim representing a captured image including an image of the QR code from the camera 41, obtaining ink information from the imaging data Dim, and sending it to the print execution control unit 150. This makes it possible to prevent the use of inappropriate ink.

1.4 Configuration and operation for detecting remaining ink level
Next, the configuration and operation for detecting the remaining amount of ink (hereinafter simply referred to as "remaining amount of ink") in the ink tank 32 provided in each of the four ink supply devices 30C, 30M, 30Y, and 30K in this embodiment will be described with a focus on one ink supply device 30 among these four ink supply devices 30C, 30M, 30Y, and 30K (see FIG. 3). Note that hereinafter, among the main body 31 of the ink supply mechanism 300, its platform portion 31a, and its wall portion 31b (see FIG. 2), the portions corresponding to the ink supply device 30 of interest will also be referred to as the "main body 31," the "platform portion 31a," and the "wall portion 31b."

FIG. 6 is a diagram for explaining the configuration for detecting the remaining ink amount in this embodiment. In the ink supply device 30 in this embodiment, the main body 31 has a platform portion 31a with a horizontal upper surface and a wall portion 31b with a vertical front surface. A plate-like member 331 configured to be rotatable around a rotation axis 331a fixed to the upper surface of the platform portion 31a of the main body 31 is attached, and the rotation axis 331a is arranged so that it is parallel to the front surface of the wall portion 51b of the main body 31. The ink tank 32 is attached so that its bottom surface is fixed to the upper surface of the plate-like member 331 by a mounting member (not shown). This plate-like member 331 is configured so that the rotation axis 331a is parallel to the lower side of the back surface 32B of the ink tank 32 when the ink tank 32 is mounted thereon. An elastic member 332 is interposed between the plate-like member 331 and the platform portion 31a of the main body 31, and the plate-like member 331, the platform portion 31a, and the elastic member 332 form a tank support mechanism 330 for the ink tank 32. In this way, the tank support mechanism 330 supports the ink tank 32 attached to the plate-like member 331 with the elastic member 332, and is configured so that (the bottom surface of) the ink tank 32 is tilted with respect to the horizontal plane depending on the weight of the ink tank 32.

In the example shown in FIG. 6, the elastic member 332 interposed between the plate-like member 331 and the platform portion 31a of the main body 31 is a spring, but it may be a leaf spring or other elastic member instead. Also, in FIG. 6, the tank support mechanism 330 is shown diagrammatically, and the specific configuration of the tank support mechanism 330 (the number, shape, size, arrangement, etc. of the elastic members 332) is appropriately designed to suit the purpose described below of detecting the remaining ink amount by the inclination of the ink tank 32 (the inclination of the plate-like member 331). In this embodiment, the ink tank 32 is an opaque container, but in FIG. 6, for convenience of explanation, the ink tank 32 is drawn as if it were a transparent container (the same applies to FIGS. 6A to 19 described below).

As shown in FIG. 6, a QR code label 51 recording ink information (ink ingredients, manufacturing date, color, model number, etc.) is affixed to the surface of the rectangular parallelepiped container serving as the ink tank 32 that faces the front surface of the wall portion 31b of the main body 31, i.e., the back surface 32B. A camera 41 for capturing an image of this label 51 is built into the wall portion 31b of the main body 31.

FIG. 7A shows the state of the ink supply device 30 in this embodiment when a large amount of ink remains, and FIG. 7B shows the state of the ink supply device 30 in this embodiment when a small amount of ink remains. When the amount of ink 35 stored in the ink tank 32 attached to the ink supply device 30 (ink remaining amount) is large, the weight of the ink tank 32 is large, and therefore, as shown in FIG. 7A, the inclination θ1 of the plate-like member 331 to which the bottom surface of the ink tank 32 is fixed relative to the horizontal plane (hereinafter simply referred to as the "inclination of the ink tank 32") is small. FIG. 7A also shows the captured image Im represented by the imaging data Dim obtained from the camera 41 at this time.

In contrast, when the amount of ink 35 stored in the ink tank 32 attached to the ink supply device 30 (remaining ink amount) is small, the weight of the ink tank 32 is small, and therefore the inclination θ2 of the ink tank 32 is large, as shown in Figure 7B. Figure 7B also shows the captured image Im represented by the imaging data Dim obtained from the camera 41 at this time.

As described above, the inclination θ2 when the ink level is low is greater than the inclination θ1 when the ink level is high. When the inclination θ of the ink tank 32 differs in this way, the vertical distance between the two predetermined patterns that are spaced apart in the vertical direction in the captured image Im differs according to the difference in the inclination. In other words, the vertical distance between the two predetermined patterns in the captured image Im changes according to the ink level. For example, the vertical distance h2 between the upper and lower sides of the QR code label 51 in the captured image Im obtained when the ink level is low is smaller than the vertical distance h1 between the upper and lower sides of the QR code label 51 in the captured image Im obtained when the ink level is high. Therefore, the ink level can be estimated by determining the vertical distance between the upper and lower sides of the QR code label 51 from the captured image data Dim obtained by the camera 41 provided to read the QR code on which the ink information is recorded. However, the color of the label 51 is different from the color of the outer surface of the ink tank 32.

In the control unit 100 of this embodiment, the CPU 111 performs the remaining ink amount detection process described below, thereby realizing the remaining ink amount detection processing unit 160 (see FIG. 5) including the image analysis unit 162 and remaining ink amount determination unit 164 described above in software.

FIG. 8 is a flowchart showing an example of the ink remaining amount detection process in this embodiment. In this ink remaining amount detection process, the CPU 111 operates as follows.

First, the imaging data Dim generated by imaging the QR code label 51 is received from the camera 41 (step S10). Next, based on this imaging data Dim, two linear patterns indicating the upper and lower ends, i.e., the upper and lower sides, of the label 51 are extracted from the imaging image (image represented by the imaging data Dim) Im (step S12), and the interval between the two extracted linear patterns is obtained. Since the magnitude of this interval h corresponds to the magnitude of the inclination θ of the ink tank 32, the inclination θ of the ink tank 32 is obtained based on this interval h (step S16). For example, a lookup table showing the relationship between this interval h and the inclination θ of the ink tank 32 is created in advance, and the inclination θ of the ink tank 32 is obtained from the interval h of the two linear patterns by referring to the lookup table. Alternatively, instead of such a lookup table, a formula showing the relationship may be obtained in advance. After that, the remaining ink amount Aik is determined based on the inclination θ of the ink tank 32 obtained in this way (step S18). Specifically, as described above, a lookup table or formula that indicates the relationship between the inclination θ of the ink tank 32 and the remaining ink amount Aik is created in advance, and the remaining ink amount Aik is determined from the inclination θ using the lookup table or formula. Once the remaining ink amount Aik has been determined in this manner, the remaining ink amount detection process ends.

In the remaining ink amount detection process shown in FIG. 8, steps S10 to S16 implement the image analysis unit 162 shown in FIG. 5, and step S18 implements the remaining ink amount determination unit 164 shown in FIG. 5.

FIG. 9 is a flow chart showing another example of the ink remaining amount detection process in this embodiment. In the ink remaining amount detection process shown in FIG. 8, the inclination θ is calculated by focusing on the fact that the distance between the top and bottom sides of the QR code label 51 changes depending on the inclination θ of the ink tank 32, whereas in the ink remaining amount detection process shown in FIG. 9, the inclination θ is calculated by focusing on the fact that the distance d (see FIG. 10) between two cut-out symbols (finder patterns) spaced apart in the vertical direction as cut-out symbols serving as indicators included in the QR code in the captured image Im changes depending on the inclination θ of the ink tank 32. In this ink remaining amount detection process (another example), the CPU 111 operates as follows.

First, similar to step S10 shown in FIG. 8, image data Dim generated by imaging the QR code label 51 is received from the camera 41 (step S20). Next, based on this image data Dim, two cut-out symbols separated in the vertical direction from the cut-out symbols contained in the QR code are extracted from the captured image Im (step S22), and the distance d between the two extracted cut-out symbols is obtained. Since the size of this distance d corresponds to the inclination θ of the ink tank 32, the inclination θ of the ink tank 32 is obtained based on this distance d (step S26). Then, similar to step S18 shown in FIG. 8, the remaining ink amount Aik is determined based on the obtained inclination θ of the ink tank 32 (step S28), and the ink remaining amount detection process is terminated.

In the remaining ink amount detection process shown in FIG. 9, steps S20 to S26 implement the image analysis unit 162 shown in FIG. 5, and step S28 implements the remaining ink amount determination unit 164 shown in FIG. 5.

<1.5 Effects>
As described above, in this embodiment, the tank support mechanism 330 in the ink supply device 30 is configured so that the ink tank 32 is tilted in accordance with the weight of the ink tank 32 (so that the plate-like member 331 to which the bottom surface of the ink tank 32 is fixed is tilted with respect to the horizontal plane) as shown in Figures 7A and 7B. The tilt θ of the ink tank 32 is obtained by using a camera 41 provided to read the QR code attached to the ink tank 32 and obtain ink information (see Figures 6, 8, and 9). That is, an image analysis is performed on the captured image Im based on the imaging data Dim generated by the camera 41, and the vertical distance between two predetermined patterns (the distance h between the upper and lower sides of the label 51 or the vertical distance d between two cut-out symbols in the QR code) is obtained as a result of the analysis, and the tilt θ of the ink tank 32 is obtained based on this distance. In this way, the camera 41 that captures the image of the QR code label 51 and software processing such as image analysis based on the captured image data Dim can detect the remaining ink amount with less maintenance cost than when a float is used in the ink tank, and can detect the remaining ink amount with higher accuracy than a method based on the driving time of a pump for supplying ink. Moreover, in an inkjet printing device provided with a camera that captures an image of the QR code label attached to the ink tank to obtain ink information, the captured image data of the camera can be used to detect the remaining ink amount, so the remaining ink amount can be detected simply by adding the software for the ink remaining amount detection process shown in Figure 8 or Figure 9. Therefore, according to this embodiment, the remaining ink amount in a tank that stores ink in an ink supply device can be detected with high accuracy with a simple configuration that requires low maintenance cost.

1.6 Modifications
In the first embodiment, the inclination θ of the ink tank 32 is calculated from the vertical distance between two predetermined patterns in the captured image Im based on the image data Dim of the QR code label 51 attached to the rear surface 32B of the ink tank 32, and the remaining ink amount Aik is determined based on the inclination θ (see Figs. 7A, 7B, 8, and 9). If it is desired to improve the detection accuracy of the remaining ink amount more than in the first embodiment, it is possible to arrange the camera 41 at a position facing the side surface of the ink tank 32 rather than the rear surface 32B so that an image directly showing the inclination θ of the ink tank 32 can be obtained. Hereinafter, an inkjet supply device equipped with an ink supply device 30 having such a configuration will be described as a modified example of the first embodiment. Note that the hardware configuration other than the arrangement position of the camera 41 and the affixing position of the QR code label 51 is the same as in the first embodiment, and the functional configuration of the control unit 100 is also the same as in the first embodiment (see Fig. 5), so that the same or corresponding parts are given the same reference numerals and detailed description is omitted. The remaining ink amount detection process in this modified example differs from the remaining ink amount detection process (FIGS. 8 and 9) in the first embodiment, and will be described later.

FIG. 11A is a diagram for explaining the configuration for detecting the remaining ink amount in the ink supply device 30 in this modified example. FIG. 11B is a diagram showing an image Im obtained in this modified example. Unlike the first embodiment in which a QR code label was affixed to the back surface 32B of the ink tank 32 as shown in FIG. 6, in this modified example, a QR code label 51 is affixed to the side surface of the ink tank 32 as shown in FIG. 11A. The camera 41 in this modified example is positioned so that it faces the side surface to which the QR code label 51 is affixed, i.e., the imaging direction of the camera 41 is perpendicular to that side surface (see FIG. 20 described below).

In this configuration, the camera 41 obtains a captured image Im as shown in FIG. 11B. The captured image data Dim (image data representing the captured image Im) generated by the camera 41 is sent to the control unit 100, and the CPU 111 performs the remaining ink amount detection process as shown in FIG. 12, thereby realizing in software the remaining ink amount detection processing unit 160 including the image analysis unit 162 and remaining ink amount determination unit 164 shown in FIG. 5.

FIG. 12 is a flowchart showing an example of the remaining ink amount detection process in this modified example. In this remaining ink amount detection process, the CPU 111 operates as follows.

First, the imaging data Dim generated by imaging the QR code label 51 on the side of the ink tank 32 is received from the camera 41 (step S30). Next, based on this imaging data Dim, a linear pattern indicating the bottom side of the side of the ink tank 32 is extracted from the captured image Im (step S32), and the inclination of the extracted linear pattern with respect to the horizontal direction is obtained as the inclination θ of the ink tank 32 (step S34). For example, in addition to the linear pattern indicating the bottom side of the side of the ink tank 32, a linear pattern indicating the horizontal upper surface of the platform portion 31a of the main body 31 is extracted from the captured image Im, and the angle between these two linear patterns is obtained as the inclination θ of the ink tank 32. Thereafter, the remaining ink amount Aik is determined based on the inclination θ of the ink tank 32 thus obtained (step S36), and the ink remaining amount detection process is terminated.

In the remaining ink amount detection process shown in FIG. 12, steps S30 to S34 implement the image analysis unit 162 shown in FIG. 5, and step S36 implements the remaining ink amount determination unit 164 shown in FIG. 5.

In this modified example, as in the first embodiment, the inclination θ of the ink tank 32 is obtained using the camera 41 provided to read the QR code attached to the ink tank 32 and obtain ink information, and the remaining ink amount Aik is determined based on this inclination θ, so that the same effect as the first embodiment can be obtained. Furthermore, in this modified example, the inclination θ of the ink tank 32 is obtained directly from the imaging data Dim (FIGS. 11 and 12), so the remaining ink amount can be detected with higher accuracy than in the first embodiment. On the other hand, in this modified example, the camera 41 is disposed on the side of the ink tank 32 (FIGS. 11 and 20), so a larger space is required in the side direction of the ink tank 32 compared to the first embodiment (FIG. 6) in which the camera 41 was built into the main body 31 of the ink supply device 30.

2. Second embodiment
In the first embodiment, as shown in Figs. 7A and 7B, the tank support mechanism 330 is configured so that the ink tank 32 tilts depending on the weight of the ink tank 32 it supports. However, when the capacity of the ink tank 32 is large (for example, when the capacity exceeds 200 liters), it is preferable to avoid a configuration in which the ink tank 32 tilts from the viewpoint of stability and safety. Therefore, in the inkjet printing device according to the second embodiment, the tank support mechanism 330 is configured so that the ink tank 32 changes its vertical position without tilting depending on the weight of the ink tank 32 it supports. Hereinafter, such a second embodiment will be described. Note that the other hardware configurations in this embodiment except for the tank support mechanism 330 are the same as those in the first embodiment, and the functional configuration of the control unit 100 is also basically the same as that in the first embodiment (see Fig. 5), so that the same or corresponding parts are denoted by the same reference numerals and detailed description will be omitted. The specific content of the ink remaining amount detection process in this embodiment is different from the ink remaining amount detection process (Figs. 8 and 9) in the first embodiment, and will be described later.

2.1 Configuration and operation for detecting remaining ink level
Below, the configuration and operation for detecting the remaining amount of ink in the ink tanks 32 provided in each of the four ink supply devices 30C, 30M, 30Y, and 30K in this embodiment will be explained, focusing on one ink supply device 30 out of these four ink supply devices 30C, 30M, 30Y, and 30K (see Figure 3).

FIG. 13 is a diagram for explaining the configuration for detecting the remaining ink amount in this embodiment. In the ink supply device 30 in this embodiment, the main body 31 has a platform portion 31a having a horizontal upper surface and a wall portion 31b having a vertical front surface, as in the first embodiment. A plate member 331 is attached to the upper surface of the platform portion 31a of the main body 31 via an elastic member 332. The ink tank 32 is attached so that its bottom surface is fixed to the upper surface of the plate member 331 by a member not shown. This plate member 331 is configured so that when the ink tank 32 is attached thereto, the back surface 32B of the ink tank 32 is parallel to the front surface of the wall portion 31b of the main body 31. The plate member 331, the platform portion 31a of the main body 31, and the elastic member 332 constitute a support mechanism 330 for the ink tank 32. In this way, the tank support mechanism 330 supports the ink tank 32 attached to the plate-like member 331 with the elastic member 332, and is configured so that the vertical position of the ink tank 32 changes depending on the weight of the ink tank 32.

In the example shown in FIG. 13, the elastic member interposed between the plate-like member 331 and the platform portion 31a of the main body 31 is a spring 332, but other elastic members such as a leaf spring may be used instead. Also, in FIG. 13, the tank support mechanism 330 is shown diagrammatically, and the specific configuration of the tank support mechanism 330 (the number, shape, size, arrangement, etc. of the elastic members 332) is appropriately designed to suit the purpose of detecting the remaining amount of ink based on the vertical position of the ink tank 32.

As shown in FIG. 13, in this embodiment, as in the first embodiment, a QR code label 51 recording ink information (ink ingredients, manufacturing date, color, model number, etc.) is affixed to the back surface 32B of the rectangular parallelepiped container serving as the ink tank 32. A camera 41 for capturing an image of this label 51 is built into the wall portion 31b of the main body 31.

FIG. 14A shows the state of the ink supply device 30 when a large amount of ink remains in this embodiment, and FIG. 14B shows the state of the ink supply device 30 when a small amount of ink remains in this embodiment. When the amount of ink 35 stored in the ink tank 32 attached to the ink supply device 30 (ink remaining amount) is large, the weight of the ink tank 32 is large, and so the vertical position of the ink tank 32 is low, as shown in FIG. 14A. FIG. 14A also shows the captured image Im represented by the imaging data Dim obtained from the camera 41 at this time.

In contrast, when the amount of ink 35 stored in the ink tank 32 attached to the ink supply device 30 (remaining ink amount) is small, the weight of the ink tank 32 is small, and therefore the vertical position of the ink tank 32 is high, as shown in Figure 14B. Figure 14B also shows the captured image Im represented by the imaging data Dim obtained from the camera 41 at this time.

As described above, the vertical position of the ink tank 32 changes depending on the amount of remaining ink; the less the amount of remaining ink, the higher the vertical position. Such changes in the vertical position of the ink tank 32 can be obtained from the image Im captured by the camera 41. Therefore, position information indicating the vertical position of the ink tank 32 in the captured image Im can be obtained based on the image data Dim, and the amount of remaining ink can be estimated from the position information.

In the control unit 100 of this embodiment, the CPU 111 performs the remaining ink detection process described below, thereby realizing the remaining ink detection processing unit 160, which includes the image analysis unit 162 and remaining ink determination unit 164 described above, in software.

FIG. 15 is a flowchart showing a first example of the ink remaining amount detection process in this embodiment. In this ink remaining amount detection process, the CPU 111 operates as follows.

First, as in the first embodiment, the imaging data Dim generated by imaging the QR code label 51 is received from the camera 41 (step S40). Next, based on this imaging data Dim, a linear pattern indicating the upper side of the back surface 32B of the ink tank 32 is extracted from the captured image Im (step S42), and the vertical position of the extracted linear pattern is determined. Here, the distance h from the lower end of the captured image Im to the linear pattern (hereinafter referred to as the "tank upper end position") is determined, and this is used as position information indicating the vertical position of the upper side of the back surface 32B of the ink tank 32. Note that in Figures 14A and 14B, the hatched area in the captured image Im indicates the outer surface (back surface 32B) of the ink tank 32. The tank upper end position h1 in the captured image Im when the ink level is high as shown in Figure 14A is lower than the tank upper end position h2 in the captured image Im when the ink level is low as shown in Figure 14B.

In this way, once the tank top end position h in the captured image Im is obtained as position information indicating the vertical position of the ink tank 32, the remaining ink amount Aik is then determined based on this tank top end position h. For example, a lookup table showing the relationship between this tank top end position h and the remaining ink amount Aik is created in advance, and the remaining ink amount Aik is determined from the tank top end position h in the captured image Im by referencing this lookup table. Also, instead of such a lookup table, a mathematical formula showing this relationship may be obtained in advance. Once the remaining ink amount Aik has been determined in this way, the remaining ink amount detection process ends.

In the remaining ink amount detection process shown in FIG. 15, steps S40 to S44 implement the image analysis unit 162 shown in FIG. 5, and step S46 implements the remaining ink amount determination unit 164 shown in FIG. 5.

FIG. 16 is a flow chart showing a second example of the remaining ink amount detection process in this embodiment. In the first example of the remaining ink amount detection process shown in FIG. 15, the tank top end position h in the captured image Im is obtained as position information indicating the vertical position of the ink tank 32, whereas in the second example, the height of the linear pattern indicating the top end of the QR code label 51 in the captured image Im is obtained as position information indicating the vertical position of the ink tank 32. In this second example of remaining ink amount processing, the CPU 111 operates as follows.

First, similar to step S10 shown in FIG. 8, image data Dim generated by imaging the QR code label 51 is received from the camera 41 (step S50). Next, based on this image data Dim, a linear pattern indicating the top end of the QR code label 51 is extracted from the captured image Im (step S52), and the vertical position of the extracted linear pattern is determined. Here, the distance from the bottom end of the captured image Im to the linear pattern (hereinafter referred to as the "label top end position") is determined, and this is used as position information indicating the vertical position of the ink tank 32. Note that instead of determining the label top end position, the distance from the bottom end of the captured image Im to the linear pattern indicating the bottom end of the QR code label 51 (hereinafter referred to as the "label bottom end position") may be determined.

In this way, once the position of the top end of the label in the captured image Im is obtained as position information indicating the vertical position of the ink tank 32, the remaining ink amount Aik is then determined based on this position of the top end of the label. For example, a lookup table showing the relationship between the position of the top end of the label and the remaining ink amount Aik is created in advance, and the remaining ink amount Aik is determined from the position of the top end of the label in the captured image Im by referring to this lookup table. Also, instead of such a lookup table, a formula showing this relationship may be obtained in advance. Once the remaining ink amount Aik has been determined in this way, the remaining ink amount detection process ends.

In the remaining ink amount detection process shown in FIG. 16, steps S50 to S54 implement the image analysis unit 162 shown in FIG. 5, and step S56 implements the remaining ink amount determination unit 164 shown in FIG. 5.

FIG. 17 is a flow chart showing a third example of the remaining ink amount detection process in this embodiment. In this third example, a predetermined cut-out symbol contained in a QR code is extracted from the captured image Im, and the vertical position of this cut-out symbol is obtained as position information indicating the vertical position of the ink tank 32. In this third example of remaining ink amount processing, the CPU 111 operates as follows.

First, the imaging data Dim generated by imaging the QR code label 51 is received from the camera 41 (step S60). Next, based on this imaging data Dim, a specific cut-out symbol (for example, the upper left cut-out symbol in the QR code shown in FIG. 10) is extracted from among the cut-out symbols contained in the QR code in the captured image Im (step S62), and the vertical position of the extracted cut-out symbol in the captured image Im is determined (step S64). Here, the distance from the bottom edge of the captured image Im to the cut-out symbol (hereinafter referred to as the "vertical position of the symbol") is determined, and this is used as position information indicating the vertical position of the ink tank 32.

In this way, once the vertical position of the symbol in the captured image Im is determined as position information indicating the vertical position of the ink tank 32, the remaining ink amount Aik is then determined based on this vertical position of the symbol. For example, a lookup table showing the relationship between the vertical position of the symbol and the remaining ink amount Aik is created in advance, and the remaining ink amount Aik is determined from the vertical position of the symbol in the captured image Im by referring to this lookup table. Also, instead of such a lookup table, a mathematical formula showing this relationship may be determined in advance. Once the remaining ink amount Aik has been determined in this way, the remaining ink amount detection process ends.

In the remaining ink amount detection process shown in FIG. 17, steps S60 to S64 implement the image analysis unit 162 shown in FIG. 5, and step S66 implements the remaining ink amount determination unit 164 shown in FIG. 5.

2.2 Effects
As described above, in this embodiment, the tank support mechanism 330 in the ink supply device 30 is configured so that the vertical position of the ink tank 32 changes depending on the weight of the ink tank 32, as shown in Figures 14A and 14B. The vertical position of the ink tank 32 is determined using a camera 41 provided to read the QR code attached to the ink tank 32 and obtain ink information (see Figures 13, 15 to 17). That is, image analysis is performed on the captured image Im based on the image data Dim generated by the camera 41, and the vertical position of a predetermined linear pattern or a predetermined cut-out symbol as a result of the analysis is obtained, and the remaining ink amount is determined based on this vertical position (see Figures 15 to 17). In this way, as in the first embodiment, the remaining ink amount is detected by the camera 41 that captures the QR code label 51 and software processing such as image analysis based on the image data Dim. Therefore, according to this embodiment, as in the first embodiment, the remaining ink amount in a tank that stores ink in the ink supply device is accurately detected with a simple configuration with low maintenance costs.

In this embodiment, the tank support mechanism 330 is configured to change the vertical position of the ink tank 32 attached to the ink supply device 30 in accordance with its weight without tilting (FIGS. 14A and 14B). Therefore, even when using an ink tank 32 with a larger capacity than in the first embodiment, ink can be stably and safely supplied to the printing mechanism 200 while detecting the remaining ink level.

3. Advantages and disadvantages of configurations for detecting remaining ink level
The following three configurations for detecting the remaining ink level have been described above. The advantages and disadvantages of these three configurations will now be described.
(1) Configuration 1: As shown in FIG. 18 , the ink tank 32 is supported so that it tilts according to its weight, and the camera 41 is positioned so that the rear surface 32B of the ink tank 32 is imaged from the front of the device body 31 (the configuration adopted in the first embodiment described above).
(2) Configuration 2: As shown in FIG. 19, a configuration in which the ink tank 32 is supported so that the ink tank 32 does not tilt and its vertical position changes according to its weight, while the camera 41 is positioned so that the rear surface 32B of the ink tank 32 is imaged from the front of the device main body 31 (the configuration adopted in the second embodiment described above).
(3) Configuration 3: As shown in FIG. 20 , the ink tank 32 is supported so that it tilts according to its weight, and the camera 41 is positioned so that the side of the ink tank 32 is imaged (the configuration adopted in the modified example of the first embodiment described above).

Configuration 1 is advantageous in that the ink tank is configured to tilt (rotate around pivot axis 331a) according to its weight, so the range of movement of the ink tank is small. On the other hand, configuration 1 is disadvantageous in that the configuration of the tank support mechanism 330 is more complex than the tank support mechanism 330 in configuration 2, and configuration 1 is disadvantageous in terms of the accuracy of detecting the remaining ink amount, because the tilt θ of the ink tank is calculated based on the distance between two patterns spaced apart in the vertical direction in the captured image Im, and the remaining ink amount Aik is determined based on this tilt.

Configuration 2 is advantageous in that the configuration of the tank support mechanism 330 is simpler than configuration 1 and ink can be stably and safely supplied to the printing mechanism 200 while detecting the amount of remaining ink, even when the capacity of the ink tank is large, since the ink tank is configured to change its vertical position according to its weight without tilting. On the other hand, configuration 2 is disadvantageous in that the ink tank moves over a larger range according to the amount of remaining ink than configurations 1 and 2, and the ink tank needs to be mounted on the tank support mechanism with high accuracy.

Configuration 3 is advantageous over configuration 1 in that the ink tank is configured to tilt according to its weight, and camera 41 is positioned so that the tilt θ of the ink tank is directly imaged from the side, allowing the remaining ink level to be detected with high accuracy. On the other hand, configuration 3 is disadvantageous in that camera 41 is not built into device body 31, but is positioned to face the side of the ink tank, requiring space to the side of the ink tank, making the ink supply device 30 larger than configurations 1 and 3.

4. Modifications
The present invention is not limited to the above-described embodiment and the above-described modified examples, and various modifications can be made without departing from the scope of the present invention.

For example, in each of the above embodiments, a camera that captures an image of a label 51 such as a QR code on which ink information is recorded (hereinafter referred to as an "ink information acquisition camera") is used as an imaging unit for detecting the amount of ink remaining in the ink tank 32, but the present invention can also be applied to inkjet printing devices that are not provided with such an ink information acquisition camera by providing a camera for detecting the amount of ink remaining. Furthermore, in inkjet printing devices that are provided with such a camera for acquiring ink information, a separate camera for detecting the amount of ink remaining may also be provided.

In addition, in each of the above embodiments, the camera 41 is positioned to face the back or side of the rectangular parallelepiped ink tank 32, but the camera may be positioned in another location (for example, facing the front of the ink tank 32) without going against the spirit of the present invention. However, when changing the camera position, the surface of the ink tank 32 on which the QR code label 51 is affixed should be changed as necessary.

In addition, in each of the above embodiments, the camera 41 is positioned to capture an image of the QR code label 51, but the camera 41 may be configured to capture an image of a label other than the QR code label 51 that is a color different from the color of the outer surface of the ink tank 32. In addition, when the remaining ink amount is determined based on the vertical position of the ink tank 32 that is obtained based on the linear pattern indicating the upper end of the ink tank 32 (the upper side of the back surface 32B) in the captured image Im as in the first example (Figure 15) of the above second embodiment, the camera 41 may be positioned to face the surface of the outer surface of the ink tank 32 that does not have a label 51 such as a QR code attached.

In the above embodiments and modifications, the ink tank 32 is a rectangular parallelepiped container, but containers of other shapes (for example, cylindrical containers) may be used as long as they do not deviate from the spirit of the present invention. In the above embodiments and modifications, the label 51 including the QR code is affixed to the ink tank 32, but other two-dimensional bar codes, or more generally, other image codes that represent an identification code as an image, may be used instead of the QR code. Furthermore, instead of affixing the label 51 including the QR code to the ink tank 32, an image code such as a QR code may be recorded directly on the outer surface (back or side, etc.) of the ink tank 32.

5...Paper (recording media)
10 ... Inkjet printing device 17 ... Printing control program 20C, 20M, 20Y, 20K ... Recording head 22C, 22M, 22Y, 22K ... Sub-tank 30C, 30M, 30Y, 30K ... Ink supply device 32 ... Ink tank (main tank)
32B ... (back side of ink tank) 35 ... ink 41 ... camera (imaging unit)
51 QR code label 100 control unit 111 CPU
REFERENCE SIGNS LIST 150 Print execution control unit 152 Ink supply control unit 160 Ink remaining amount detection processing unit 162 Image analysis unit 164 Ink remaining amount determination unit 200 Print mechanism 300 Ink supply mechanism 330 Tank support mechanism 332 Elastic member Dim Image data Im Imaged image

Claims (16)

A tank for storing ink;
a support mechanism that supports the tank such that a vertical position or an inclination of the tank changes according to a weight of the tank, the support mechanism including an elastic member that supports a bottom surface of the tank;
an imaging unit that images the tank and generates imaging data showing at least a portion of the tank;
an image analysis unit that determines the vertical position or the inclination based on the imaging data;
an ink remaining amount determination unit that determines the remaining amount of ink in the tank based on the vertical position or the inclination obtained by the image analysis unit. The tank has a front surface, a back surface and two sides;
the support mechanism is configured to support the tank such that lower sides of the two side surfaces are inclined relative to a horizontal direction in response to a weight of the tank,
the imaging unit is disposed at a position capable of imaging one of the front surface, the back surface, and the two side surfaces,
the image analysis unit extracts a specific pattern in an image represented by the imaging data based on the imaging data, and determines the inclination based on the extracted specific pattern;
The ink supply device according to claim 1 , wherein the remaining ink amount determination unit determines the remaining ink amount based on the gradient obtained by the image analysis unit. the imaging unit is disposed at a position capable of imaging one of the front surface and the back surface,
a label attached to said one surface;
the specific pattern is two linear patterns indicating the upper and lower ends of the label,
The ink supply device according to claim 2 , wherein the image analysis section determines a distance between the two linear patterns in the image represented by the imaging data, and determines the inclination based on the distance. the imaging unit is disposed at a position capable of imaging one of the two side surfaces,
the specific pattern is a linear pattern indicating a lower side of the one surface,
The ink supply device according to claim 2 , wherein the image analysis section determines, as the inclination, an angle that the linear pattern makes with respect to a horizontal direction in the image represented by the imaging data. the imaging unit is disposed at a position capable of imaging one of the front surface and the back surface,
a mark including two indicators spaced apart in a vertical direction is provided on one of the front surface and the back surface;
the specific pattern is a pattern indicating the two indicators,
The ink supply device according to claim 2 , wherein the image analysis section determines a distance between the two indices in the image represented by the imaging data, and determines the inclination based on the distance. The mark is a QR code (registered trademark),
The ink supply device according to claim 5 , wherein the two indicators are two cut-out symbols vertically spaced apart from each other among the cut-out symbols in the QR code. the support mechanism includes a rotation shaft portion that is provided on a plate-like member to which a bottom surface of the tank is fixed and extends parallel to a lower side of the back surface,
the elastic member is disposed so as to support the bottom surface directly or via the plate-like member at a position spaced from the pivot shaft portion,
The ink supply device according to claim 2 , wherein the support mechanism supports the tank so as to rotate about the rotation shaft portion in accordance with a weight of the tank. the support mechanism supports the tank such that the tank does not tilt and the vertical position of the tank changes in response to the weight of the tank,
The tank has a front surface, a back surface and two sides;
the imaging unit is disposed at a position capable of imaging one of the front surface, the back surface, and the two side surfaces,
the image analysis unit extracts a specific pattern in an image represented by the imaging data based on the imaging data, and determines a vertical position of the extracted specific pattern;
The ink supply device according to claim 1 , wherein the remaining ink amount determination unit determines the remaining ink amount based on the vertical position of the specific pattern obtained by the image analysis unit. The ink supply device of claim 8, wherein the specific pattern is a linear pattern that indicates the upper or lower edge of the one surface. a label attached to said one surface;
The ink supply device according to claim 8 , wherein the specific pattern is a linear pattern indicating an upper end or a lower end of the label. A mark including an index is provided on the one surface,
the specific pattern is a pattern indicating the index,
The image analysis unit determines a vertical position of the index in the image represented by the imaging data,
The ink supply device according to claim 8 , wherein the remaining ink amount determination unit determines the remaining ink amount based on the vertical position of the indicator obtained by the image analysis unit.
Ink supply device. The mark is a QR code,
The ink supply device according to claim 11 , wherein the indicator is a specific cut-out symbol among cut-out symbols included in the QR code. the label includes a QR code for recording ink information;
The ink supply device according to claim 3 , wherein the image analysis section acquires the ink information from the imaging data. the mark is a QR code that records ink information related to the ink stored in the tank to which the mark is attached,
The ink supply device according to claim 5 , 6 , 11 , or 12 , wherein the image analysis section acquires the ink information from the imaging data. A conveying mechanism for conveying a long recording medium;
a recording head that ejects ink onto the recording medium;
a print execution control unit that controls the recording head and the transport mechanism so that a print image is formed on the recording medium;
An inkjet printing apparatus comprising: an ink supply device according to claim 1 , which supplies ink to be ejected by the recording head. 1. An ink supply method for supplying ink from a tank that stores ink in an ink supply device, comprising:
an ink remaining amount detection step for detecting the amount of ink remaining in the tank;
The ink supply device includes:
a support mechanism that supports the tank such that a vertical position or an inclination of the tank changes according to a weight of the tank, the support mechanism including an elastic member that supports a bottom surface of the tank;
an imaging unit that images the tank,
The ink remaining amount detection step includes:
an imaging step of imaging the tank by the imaging unit and generating imaging data showing at least a portion of the tank;
an image analysis step of determining the vertical position or the inclination based on the imaging data;
and determining a remaining amount of ink in the tank based on the vertical position or the inclination determined in the image analysis step.

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