JPH05207267A - Printer - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to provide pixel information in the sub-scanning direction to an interpolation circuit and omit the line memory to achieve cost reduction. In a printer having a first printing mode for printing at high resolution and a second printing mode for printing at low resolution, an image forming unit 100 uses a page memory 102 to store pixel data for one page. Among the pixel data of one page stored and stored in the page memory 102 by a plurality of transmission paths, a plurality of adjacent pixel data (output 302) in the sub-operation direction are transmitted in parallel, and the printing mechanism 200 transmits a plurality of transmissions. The pixel data (output 302) sent on the road is received, interpolation is performed by the interpolation circuit 206 in the case of the second print mode, printing is performed, and printing is performed without passing through the interpolation circuit 206 in the case of the first print mode. I do.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus, for example, a printing apparatus that performs parallel transmission in data transfer between a printing mechanism and an image forming unit and performs interpolation processing in the printing mechanism.

[0002]

2. Description of the Related Art Conventionally, in a scanning type image recording apparatus such as a laser printer, at a printing speed of a popular type machine,
In the case of 8 sheets / minute, 300 dpi, A4 machine, the transmission clock of one pixel was about 2 MHz, and the circuit configuration could be made by relatively inexpensive electric parts.

However, in order to obtain higher quality print output, the resolution tends to increase.

The image transmission clock also tends to rise due to the influence of the decrease in the number of polygonal surfaces for the purpose of cost reduction.

As a result, the clock for signal processing rises extremely, causing problems such as generation of noise in the transmission system. Countermeasures for radiation noise and the use of high-speed operating parts are required, which causes a cost increase.

Therefore, in order to reduce the transmission clock, the data transmitted from the image forming section is simultaneously transmitted in parallel in several consecutive pixels in the main scanning direction to suppress the transmission speed, and the parallel printing is performed in the printing mechanism. / Processing such as serial conversion and printing is conceivable.

On the other hand, in order to perform high-quality printing with a small amount of image memory, in recent years, data having higher resolution, gradation, etc. than the bit image data on the page memory of the image forming section has been used by the pixel interpolation technique. A method of generating and printing out in a printing mechanism has been introduced.

[0008]

However, in such a pixel interpolation technique, in order to complement one pixel, pixel information in the front, rear, left and right vicinity of the target pixel is required. Since there is only one line, for interpolation processing, it is necessary to store pixel information for several lines in order to refer to neighboring pixels in the sub-scanning direction.

Such a situation also applies to a printing apparatus having parallel transmission lines for the purpose of high speed transmission.

Since only pixels in the main scanning direction are output at the same time, only a plurality of line buffers are required in addition to the page memory. Actually, since such an interpolation circuit operates only in the low resolution printing mode, only one transmission line is enough and the others are not used.

The present invention has been made in view of the above-mentioned drawbacks of the conventional example, and an object of the present invention is to provide pixel information in the sub-scanning direction to the interpolation circuit and omit the line memory. The point is to provide a printing device that can reduce costs.

[0012]

[Means for Solving the Problems]
In order to achieve the object, a printing apparatus according to the present invention includes a plurality of transmission paths for transmitting a plurality of pixel data, a first printing mode for printing at a first resolution, and a first printing mode lower than the first resolution. In a printing device having a second printing mode for printing at a resolution of 2, a plurality of pixels are formed by using the plurality of transmission paths in both the first printing mode and the second printing mode. Receiving means for receiving data in parallel,
When the receiving unit is performed in the second print mode, an interpolating unit that interpolates a plurality of pixel data received in parallel by the receiving unit, and a plurality of receiving units that are received by the receiving unit when the interpolating unit is not executed. A first printing unit that performs printing based on pixel data and a second printing unit that performs printing based on the interpolation result of the interpolation unit when the interpolation unit executes.

[0013]

According to this structure, the receiving means is in either the first printing mode for printing at the first resolution or the second printing mode for printing at the second resolution lower than the first resolution. Also, the receiving means receives the plurality of pixel data in parallel using the plurality of transmission paths, and the interpolating means receives the plurality of pixel data received in parallel by the receiving means when performing the receiving means in the second print mode. Interpolation, the first printing means performs printing based on a plurality of pixel data received by the receiving means when the interpolation means is not executed, and the second printing means includes the first printing means and the interpolation means. When is executed, printing is performed based on the interpolation result of the interpolation means.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. <First Embodiment> FIG. 1 is a block diagram of a printing apparatus having both a plurality of general transmission lines and a single transmission line. In fact, there is a case where any one of the plurality of signal lines is used as a conventional single signal line.

In the figure, 1100 indicates an image forming section, and 1200 indicates a printing mechanism. Image forming unit 11
00 and the printing mechanism 1200, 1301 is a serial output for sending data, 1302 is an output parallelized for high-speed printing, and 1303 is an interface for taking out information of the hardware of the printing mechanism and giving a control signal. Reference numerals 1101 and 1201 denote shift registers for converting parallel data and serial data, and 110
2 is a page memory, 1202 is a selector, 1203 is a laser diode, 1204 is a polygon mirror, 1205.
Indicates photosensitive drums, respectively.

The laser diode 1203 is the photosensitive drum 1.
Drawing is performed on 205 to form a latent image. The polygon mirror 1204 performs main scanning. Sub-scanning is performed by a paper transport system (not shown). In the printing mechanism 1200, the latent electrostatic image formed on the photosensitive drum 1205 is developed with charged toner, and transferred and fixed on paper.

The selector 1202 outputs the outputs 1302 and 130.
The signal to be sent to the laser diode 1203 for printing is selected from the 1).

When performing high resolution printing, the selector 1202 outputs the parallel video I / F of the output 1302.
Sends out data in the main scanning direction and shift register 120
The parallel / serial conversion is performed at 1, and the laser diode 1203 prints out. When performing low-resolution printing, the selector 1202 selects the serial output 1301 and the data is sent to the laser diode 1203 as it is and printed out.

Although not shown, an interpolation circuit actually exists between the laser diode 1203 and the output 1301.

FIG. 2 is a diagram showing an output order of pixel data in a general circuit and an output order of pixel data in an interface having a plurality of transmission lines. The structure of the page memory is shown in FIG. Pixel on page memory is n
Expressed as _{i, j} .

As shown in FIG. 2B, in the conventional transmission circuit, if the tone of the shift register of the image forming unit is m,
y th column of n _x at a time when the output _is read in the _{y ~n x + m-1,} y pixel simultaneously shift register, n _x, was intended to be serially output from the pixels of _y in the order.

On the other hand, the outputs of the plurality of transmission lines are n _{x, y to} n _{x + p-} , where p is the tone of the shift register 1201 on the printing mechanism side, as shown in FIG. Output _{1, y} at the same time. If p = m, shift register 1
The difference between 101 and 1201 lies only in whether the shift register is in the image forming unit or in the printing mechanism, and is the same as the entire circuit.

FIG. 3 is a diagram showing the configuration of a general interpolation circuit.

In the figure, 1211-1 to 1211
i (j is a natural number) is a serial-in / parallel-out shift register. Shift register 1211-1 to 1
The shift register group constituted by 211-i stores neighboring pixel information for pixel interpolation.

1221-1 to 1221-j (j = i-
Reference numeral 1) is a line buffer, which retains information used once so that it can be reused in the next scanning. Each line buffer stores pixel information for one scanning line. 1230
Is a logical mechanism for generating interpolation information by the arrangement of neighboring pixels. Output data is generated based on the parallel output data from the shift register group.

FIG. 4 is a diagram showing the structure of the printing apparatus according to the first embodiment, FIG. 5 is a diagram for explaining the pixel transfer system according to the first embodiment, and FIG. 6 is an interpolation according to the first embodiment. It is a figure which shows the structure of a circuit.

The structure of the pixel transfer system and the interpolation mechanism according to the first embodiment will be described with reference to FIGS.

Unlike FIG. 1, FIG. 4 shows the configuration of the printing apparatus including the interpolation circuit 206. In this figure, the circuit for high resolution printing is omitted. In the figure, 100 is an image forming unit, and 200 is a printing mechanism. Similar to FIG. 1, also in FIG. 4, the image forming unit 100 has a page memory 102, and the printing mechanism 200 has a laser diode 2
03, a polygon mirror 204, and a photosensitive drum 205. The printing mechanism 200 further includes a laser diode 203.
An interpolating circuit 206 is provided in the preceding stage.

In the interpolation circuit 206 of FIG. 6, 304 is a logic mechanism, and 305-1 to 305-m are shift registers.

When performing low resolution printing, the page memory 1
It is considered that the number of bitmap data on 02 (FIG. 5) is thinned out and decreased.

Here, as the simplest example, an example in which pixels in the main scanning direction are thinned to 1/2 will be described. Note that n
In x and y, x = 2i (i is a natural number).

In this embodiment, the transmission line group of the output 302 is used even during low resolution printing. However, pixel information perpendicular to the main scan is sent to the printing mechanism.

When the print pixel is n _{x, y} and the bus width of the transmission line is m, the pixel information transmitted simultaneously from the transmission line group of the output 302 is n _{x, y-1 / 2 m} to n _{x, y.} It becomes _{y + 1 / 2m} .

These pixel columns are temporarily stored in the shift registers 305-1 to 305-m, and the output 304 obtained by interpolating based on the information is output to the laser diode 203. In the figure, in the image forming unit 100, an external device such as a host computer, a CPU and hardware for interpreting data sent from the external device to form an image, an interface with the outside, and a program are stored. ROM and the like are omitted.

Similarly, the mechanism of the printing mechanism and the control mechanism are omitted.

With the above configuration, it is possible to configure a pixel interpolating circuit in which the line buffer consisting of m columns is omitted, and it is possible to perform data interpolation between pixels.

To summarize the above-described embodiments, in the present embodiment, when a low resolution printing mode is provided in a printing apparatus having m transmission lines, the scanning lines before and after continuous scanning lines are provided. By outputting pixels in the page memory at the same time in parallel, pixel information in the sub-scanning direction is given to the interpolation circuit, and the line memory is omitted to reduce the cost.

In this case, one scan line information is sent m times.
Dummy information is given instead of the image information of the scanning line which does not exist at the start and end of scanning.

By adopting such a configuration, the line memory on the side of the printing mechanism can be omitted and the cost can be reduced.

Originally, parallel transmission was created for the purpose of simultaneous output of pixels in the main scanning direction for the purpose of high speed and high resolution printing. Naturally, it cannot be used in the high-density printing mode, but in high-resolution printing, interpolation processing is not necessary because it is originally intended to compensate for low-resolution printing.

Also, printing is possible with one transmission line 300
Interpolation processing is performed while printing at the dpi level, and the remaining multiple transmission lines are used.

Originally, in a printing mechanism capable of high-speed high-density printing, the purpose of performing such low-density printing operation is
In general, the speed of image development is much slower than that of the printing mechanism.Therefore, in order to develop an image at high speed, it is necessary to thin out pixels and substitute a low-resolution image for the image data format of the conventional machine. This is to maintain compatibility. FIG. 7 is a flowchart explaining the operation mode according to the first embodiment. First, when the operation mode is high resolution (S101), the page memory 1102 is set (S103), and the image is developed as an image (S105). Subsequently, the hardware is set (S107), and the operation of the interpolation mechanism is turned on (S10).
9), data is input from the page memory 1102,
An image is printed out from the printing mechanism 1200 (S11
1). If the operation mode is low resolution (S10
1) Although the print output is performed as in the case of the high resolution described above (S113 to S117, S121), the operation of the interpolation mechanism is turned off (S119).

As described above, according to the first embodiment, in the printing mechanism for parallel transmission, when the low resolution printing is performed, the transmission path is used for the interpolation process and the main scanning direction is used. With a configuration in which the line buffer of the pixel interpolating circuit is omitted by sending out the pixel rows aligned vertically with respect to one at a time, the cost can be reduced. <Second Embodiment> In the first embodiment described above, the number of scanning lines does not change and the method of interpolating the pixels on the main scanning is shown. The embodiment of FIG. 2 shows a configuration including scanning line interpolation.

FIG. 8 is a diagram showing the construction of the printing apparatus according to the second embodiment, FIG. 9 is a diagram for explaining the pixel transfer system according to the second embodiment, and FIG. 10 is an interpolation according to the second embodiment. It is a figure which shows the structure of a circuit.

A pixel transfer system and an interpolating mechanism according to the second embodiment will be described with reference to FIGS.

In this embodiment, since the overall structure is the same as that of the first embodiment (FIGS. 4 to 6), the reference numbers of the corresponding units are indicated by the same numbers with dashes.

Therefore, the difference from the first embodiment will be mainly described below, and the description of the same configuration will be omitted.

In the present embodiment, if the density of the scanning lines to be generated is k times the density sent from the image forming section, the paper feed speed can be changed to 1 / k times the first embodiment. Scan line interpolation is possible with the same configuration as the example, but if the sub-scanning speed, that is, the paper transport speed cannot be controlled, the scanning time for one time becomes 1 / k, so the sending clock should not be raised. In such a case, the scanning speed becomes k times, so that the speed of sending the data from the image forming unit cannot keep up. In such a case, as shown in FIG. By transmitting at the same time, data can be transmitted without raising the clock. In this embodiment, k = 2. Here, as an example, the configuration is shown by an example in which pixels in the main scanning direction are thinned to 1/2. n
_{In x and y} , x = 2i (i is a natural number).

As shown in FIG. 8 and FIG. 9, since a pixel in which either _{x or y} of n _{x, y} is an odd number does not exist in the page memory 102 ', it is generated by the interpolation circuit 206'. Print. As an alternative to not increasing the clock frequency, the number of reference pixels in the vertical direction is 1 compared to the first configuration.
/ K. For this reason, if the bus width of the transfer data is the same, the interpolation is performed from half of the data of the first embodiment, so the image quality is somewhat inferior.

In this case, since the number of pixels on the same scanning line is two, the shift register is not used, and the selectors 251-1 and 251-2 are used.
It is shown in a configuration that can be switched by 51-m. Input switching of each selector is performed at twice the transmission clock.

As described above, also in the second embodiment, the same effect as that of the first embodiment can be obtained.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device. Further, it goes without saying that the present invention can be applied to the case where it is achieved by supplying a program to a system or an apparatus.

[0053]

As described above, according to the present invention,
In the printing mechanism for parallel transmission, when performing low-resolution printing, the transmission line is used for interpolation processing, and pixel interpolation is performed by sending pixel rows that are aligned vertically to the main scanning direction at once. Cost can be reduced by omitting the line buffer of the circuit.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a printing apparatus having both a plurality of general transmission lines and a single transmission line.

FIG. 2 is an output order of pixel data in a general circuit,
It is a figure which shows the output order of the pixel data in the interface which has a some transmission line.

FIG. 3 is a diagram showing a configuration of a general interpolation circuit.

FIG. 4 is a diagram showing a configuration of a printing apparatus according to a first embodiment.

FIG. 5 is a diagram illustrating a pixel transfer system according to the first embodiment.

FIG. 6 is a diagram showing a configuration of an interpolation circuit according to the first embodiment.

FIG. 7 is a flowchart illustrating an operation mode according to the first embodiment.

FIG. 8 is a diagram showing a configuration of a printing device according to a second embodiment.

FIG. 9 is a diagram illustrating a pixel transfer system according to a second embodiment.

FIG. 10 is a diagram showing a configuration of an interpolation circuit according to a second embodiment.

[Explanation of symbols]

 100,1100 Image forming unit 102,1102 Page memory 101,201,1101,1201 Shift register 200,1200 Printing mechanism 202,1202 Selector 203,1203 Laser diode 204,1204 Polygon mirror 205 Photoconductor drum 206 Interpolation circuit 251-1 ~ 1 251-m selector 304 logic mechanism 1211-1 to 1211-n shift register 1221-1 to 1221-m line buffer

Claims (4)

[Claims] 1. A plurality of transmission paths for transmitting a plurality of pixel data, a first printing mode for printing at a first resolution, and a second printing for a second resolution lower than the first resolution.
And a receiving unit that receives a plurality of pixel data in parallel using the plurality of transmission paths in both of the first printing mode and the second printing mode. When the receiving unit is performed in the second print mode, an interpolating unit that interpolates a plurality of pixel data received in parallel by the receiving unit, and a plurality of interpolating units that are received by the receiving unit when the interpolating unit is not executed. A printing apparatus comprising: a first printing unit that performs printing based on pixel data; and a second printing unit that performs printing based on an interpolation result of the interpolation unit when the interpolation unit executes. .. 2. A plurality of pixel data received in parallel by the receiving means is a part of one page of pixel data and is a plurality of pixel data adjacent in the sub-scanning direction in the one page. The printing apparatus according to claim 1, wherein the printing apparatus is provided. 3. A printing apparatus having a first printing mode for printing at a first resolution and a second printing mode for printing at a second resolution lower than the first resolution, wherein one page Storage means for storing pixel data, and one page of pixel data stored in the storage means,
Transmission means for transmitting a plurality of pixel data in parallel; an interpolation means for interpolating a plurality of pixel data transmitted in parallel by the transmission means in the case of the second print mode; and a reception means if the interpolation means is not executed. A first printing means for performing printing based on a plurality of pixel data received by the means; and a second printing means for performing printing based on the interpolation result of the interpolation means when the interpolation means executes. A printing device characterized by. 4. The plurality of pixel data transmitted in parallel by the transmitting means is a part of pixel data for one page, and is a plurality of pixel data adjacent in the sub-scanning direction in the one page. The printer according to claim 3, wherein the printer is provided.