JPH11127312A - Image reading device - Google Patents

Abstract

(57) [Problem] To provide an image reading apparatus capable of reliably and quickly detecting the size of a document placed on a document tray without providing a special mechanism or the like. An image reading apparatus irradiates light from a light source and irradiates a document to be read, photoelectrically converts reflected light or transmitted light thereof, and extracts image information on the document as an electric signal. First reading means for reading one side of the document, second reading means for reading the other side of the document, and the second reading at a reading position by the second reading means A member having a uniform density disposed on the surface facing the means, and a boundary between the uniform density member and the end of the document is optically detected by the second reading means at the time of reading the document, so that the document width and Means for detecting the document length.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic document feeding mechanism having a function of detecting the size of a document in an image reading apparatus applied to an image scanner, a facsimile, a copying machine, and the like. The present invention relates to an image reading apparatus capable of reliably and quickly detecting the size of a read original without providing a special mechanism or the like.

[0002]

2. Description of the Related Art Conventionally, in an image reading apparatus or the like for reading an original while placing the original, a generally known method of detecting the size of the original is to perform a pre-scan process before an actual reading operation, a photo-interrupter or the like. (Japanese Patent Application Laid-Open No. 3-165175). Also, an automatic document transport mechanism is provided in which a plurality of documents are separated one by one and conveyed to a reading position, and the conveyed document itself is moved and the image data is read at a reading position by optical reading means. In the provided image reading apparatus, the width of the original is detected by a detecting means such as a photo interrupter in a state where the original is placed along a prescribed original guide (JP-A-8-290835).

[0003]

The problem to be solved by the present invention is as follows.
Japanese Patent Laid-Open No. 165175 discloses an image reading apparatus that optically detects a side edge of a document to detect a document position and a document width, thereby enabling detection of a document size without using a document guide. I have. However, the conventional document size detection method using the conventional detection means can only detect a fixed-size document, which limits the placement of the document, and also takes time for pre-scanning for size detection, resulting in an increase in reading time. Was. Furthermore, in this conventional size detection method,
After the document position and document width are detected before the document reading position, the actual reading operation is performed at the above reading position. Therefore, it is necessary to temporarily stop the conveyance of the document, and this method also increases the reading time. become. Further, the size detection method disclosed in Japanese Patent Application Laid-Open No. 8-290835 requires a plurality of sensors in order to flexibly respond to the size of a document to be read, and cannot perform fine size detection. Was. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described conventional problems, and has as its object to reliably and quickly detect the size of a document placed on a document tray without providing a special mechanism or the like. It is an object of the present invention to provide an image reading apparatus capable of performing the above.

[0004]

In order to achieve the above object, according to the first aspect of the present invention, while irradiating light from a light source and irradiating a document to be read, reflected light or transmitted light thereof is emitted. In an image reading apparatus that performs photoelectric conversion and extracts image information on a document as an electric signal, a first reading unit for reading one side of the document and a second reading unit for reading the other side of the document. Means, a member having a uniform density disposed on a surface facing the second reading means at a reading position by the second reading means, and a uniform density member provided by the second reading means at the time of reading the document. And a detecting means for optically detecting a boundary between the document and the end of the document to detect the document width and the document length. According to the image reading apparatus of the first aspect, it is possible to detect the width and length of the document while reading the document image, and to detect a wide range of document sizes without increasing the time required for the reading operation. Can be. The invention according to claim 2 is characterized in that a contact image sensor is used for the second reading means. According to the image reading device of the second aspect,
It is possible to configure an image reading device capable of reading both sides of a document without causing a large increase in the device size, and is not limited to a fixed type or an irregular type as long as a prepared image sensor can accept a reading width. It is possible to detect a wide range of document sizes. The invention described in claim 3 is characterized in that the second reading means reads the second surface of the document and detects the width and length of the document. According to the image reading apparatus of the third aspect, it is possible to configure an image reading apparatus capable of performing both-side reading without causing a large increase in the apparatus size, and to use the document size detecting means and the reading means in common. It can be used, and a structure as a document size detecting means (a detecting means using a plurality of photo interrupters or the like) is not required.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an image reading apparatus embodying the present invention. As shown in FIG. 1, in this image reading apparatus, an original placed on an original platen glass 1
The light is emitted by an illumination lamp 3 integrally formed with the first mirror 2, and the reflected light is scanned by the first mirror 2, the second mirror 4 and the third mirror 5 integrally formed. Thereafter, the reflected light is converged by the lens 31 and the SBU 20
The light is irradiated to the upper CCD 6 and photoelectrically converted. The first mirror 2, the illumination lamp 3, the second mirror 4, and the third mirror 5
Are adapted to move and scan in the direction A using the traveling body motor 7 as a drive source. Here, the illumination lamp 3, the first to third mirrors 2, 4, 5 and the CCD 6 constitute a first reading unit 103 described later. Then, the originals stacked on the original tray 8 are sent to the transport roller pair 13 and the paper discharge roller pair 14 through the reading position B by the pickup roller 9, the registration roller pair 10, the transport drum 11, and the transport roller 12, and are discharged. The paper is discharged onto the paper tray 32. Here, when the document passes through the reading position B, the original is irradiated by the illumination lamp 3 moved to the vicinity of the reading position B, and the reflected light thereof is reflected by the first mirror 2 and the second mirror integrally formed. 4. Scanning is performed by the third mirror 5. Thereafter, the reflected light is converged by the lens 31 and is irradiated on the CCD 6 to be photoelectrically converted. The pickup roller 9 and the registration roller pair 10 are driven by a sheet feeding motor (not shown), and are transported by a transport drum 11, a transport roller 12, and a transport roller pair 1.
3. The discharge roller pair 14 is a conveyance motor (not shown)
Driven by

[0006] At the reading position C, a contact image sensor 15 is provided. The contact image sensor 15 includes an LED as a light source, a lens, and a sensor element. When the document passes through the reading position C, the opposite surface (back surface) read at the reading position B is irradiated by a lamp in the contact image sensor 15 provided at the reading position C, and the reflected light is The light is converged by the lens of the contact image sensor 15, irradiated onto the sensor element of the contact image sensor 15, and photoelectrically converted. A white roller 17 is provided on the opposite surface of the contact image sensor 15 across the document, and is used as a white member for shading correction at the time of reading by the contact image sensor 15. Here, the contact image sensor 15
Constitutes a second reading unit 111 described later. An endorser unit 18 and an endorser platen 19 are provided between the transport roller pair 13 and the paper discharge roller pair 14. Endorser unit 18
Is composed of a printing portion composed of alphabetic letters and numerals in which ink is impregnated, and a pressure solenoid (not shown) for pressing the printing portion toward the endor platen. The original is stopped on the endorser unit 18, fixed in the pressing direction by the endorser platen 19, and it is possible to print unfavorable letters and numbers on the original surface by pressing the printing portion of the endorser unit 18. I have.

FIG. 2 is a functional block diagram of the image reading apparatus shown in FIG. In FIG. 2, SBU20
The reflected light of the original that has entered the CCD 6 is converted into an analog signal having a voltage value according to the light intensity in the CCD 6, and the analog signal is divided into odd bits and even bits and output. The analog image signal is SBU2
A dark potential portion is removed by an analog processing circuit (not shown) on 0, odd bits and even bits are combined, and the gain is adjusted to a predetermined amplitude.
The digital signal is input to the converter. Next, the digitized image signal is transmitted to the NIP on the SCU 21.
In U33, after shading correction, gamma correction, MTF correction and the like are performed, the data is binarized and output as a video signal together with a page synchronization signal, a line synchronization signal, and an image clock. The video signal output from the NIPU 33 is output to the option IPU 26 via the connector 34. The video signal output to the option IPU 26 is subjected to predetermined image processing in the option IPU 26, input to the SCU 21 again, and the video signal input to the SCU 21 is input to a selector (not shown). The other input of the selector is a video signal output from the NIPU 33, and the optional IPU
At 26, it is possible to select whether or not to perform image processing. The video signal output from the selector is supplied to a SiBC 35 for managing image data storage means (DRAM).
And stored in an image memory composed of a DRAM. The image data stored in the image memory is SCSI
The data is sent to the controller 36 and transferred to an external device such as a personal computer.

Next, the analog image signal photoelectrically converted by the contact image sensor 15 is digitally converted on the RSBU 16, and the digitized image signal is converted to the RSBU1.
6 after the shading correction is performed on RCU 23
Sent to The RCU 23 is composed of an image memory composed of a DRAM and SiBC which controls the image data memory.
Transfer to CU21. The image data sent from the RCU 23 to the SCU 21 and the image data output from the SiBC 35 on the SCU 21 can be switched.
One of the image data is selected and transferred to the SCSI controller 36. The CPU 3 is provided on the SCU 21.
7, ROM 38 and RAM 39 are mounted, and CPU
37 controls the SCSI controller 36 to communicate with an external device such as a personal computer. Also, the CPU 37
It also controls the timing of the traveling body motor 7, a sheet feeding motor, and a transport motor, which are stepping motors.
The ADU 30 has a function of relaying power supply of electrical components used in an automatic document feeder (ADF) unit. An input port connected to the CPU 37 on the SCU 21 is connected to the main body operation panel 28 via the IOB 24. A start switch (not shown) and an abort switch (not shown) are mounted on the main body operation panel 28. When each switch is pressed, the CPU 37 detects that the switch has been turned on via the input port.

Next, the operation of the image reading apparatus according to the present invention will be described with reference to FIG. FIG. 3 is an explanatory diagram of the operation of the image reading apparatus shown in FIGS. In FIG.
A first reading unit (first reading means) 103 for reading the first side of the document 101 reads the white reference plate 105 before reading the document 101, and the image data at this time is the reference data for shading correction. RA
M. The first reading unit 103
After reading the white reference plate 105, it moves to a predetermined first surface reading position B and stops. Next, the original 101 placed on the automatic original transport mechanism ADF is transported one sheet at a time to the reading position B by driving the paper feed motor and the transport motor under the control of a motor driver or the like on the ADU 30.
When passing through the reading position B, the first reading unit 103 reads the image information of the first surface of the document 101. The read image information is A / D
The image is converted into digital data by the converter 107 and
After image processing such as shading correction is performed in 09,
First image memory DRAM controlled by SiBC 35a
Is accumulated in Document 10 that has passed the reading position B
1 is subsequently transported to the reading position C by the transport motor. At the reading position C, the original 101 is read by the second reading unit (second reading unit) 111.
Of the second surface is read. That is, the document 101
The second reading unit 111 starts reading from a certain time before the leading end of the reading unit reaches the reading position C. Then, at the same time when the leading end of the document 101 is detected by the second reading unit 111, reading of image information on the second surface of the document 101 is started. The image information read by the second reading unit 111 is:
After being digitized by the A / D converter 113, predetermined image processing is performed by the image processing unit 115 and the SiBC 35b
Is stored in the second image memory DRAM controlled by the above.
After passing through the reading position C in this manner, the document 101 is discharged to the discharge port. The CPU (not shown)
SiBC 35a on each of the first side and the second side of the original 101,
By controlling 35b, the frame sequential image data is output from the memory DRAM and output to the external interface via the SCSI controller 36.

Next, control for detecting the position and width of the document will be described. The second reading unit 1
The opposing roller 17 that faces the document 11 via the conveyance path of the document 101 is a white roller having a uniform density on the roller surface. The density of the surface of the opposing roller 17 is intended to be separated from the background density of the document 101, and therefore must be set to a density that can be reliably separated from the background density of the document 101. The density level of a general white original is
Since the OD value (optical density) is about 0.1, it is sufficient that the density has such a level that it can be reliably separated from this density. In the present embodiment, the opposing object of the second reading unit 111 is the white roller 17, but a plate-shaped member may be used.

FIG. 4 shows the read output level of the second reading unit 111 at the reading position C. In this embodiment, the black level is described as a high level and the white level is described as a low level. Here, for simplification of description, a case where a white roller 17 as a uniform density member is read and a uniform density level is output is shown. is there. FIG.
(B) is an output level when the uniform density member 17 is read. When the original 101 reaches the reading position C, the state shown in FIG. 4A is reached, and the output level at that time is as shown in FIG. 4C. Then, the CPU 37 (1)
To (2), (1) to (3), and (4) to (2)
And the width of the document can be detected from these data. Here, position (3) indicates the start position of the document density distribution in the main scanning direction, and position (4) indicates the end position of the document density distribution in the main scanning direction. Further, the CPU 37 changes the output level of the second reading unit 111 from the state of FIG. 4B to the level state of FIG. 4C again to the level state of FIG. The length of the original in the sub-scanning direction is detected by counting the main scanning synchronization signal until the signal changes. The detection of the width and the length of the document described above is performed by a document size detection unit (detection unit) 117 on the second surface reading side of the document 101. The image reading apparatus has a configuration in which the first reading unit 103 and the second reading unit 111 can read the images on the front and back surfaces of the document by carrying the document once.

Now, the first reading unit 103
It is assumed that an instruction to read one side of the original (first side) is sent via the user interface. Document 10 placed on a document tray of an automatic document feeder (ADF)
1 is conveyed to the reading position B as described above, and the first reading unit 103 reads the image data of the first surface of the document while passing through the position B, and stores the image data in the first image memory DRAM. The document 101 is continuously transported and reaches the reading position C. The second reading unit 111 starts the reading operation of the uniform density member 17 as if reading the second surface of the document 101. The size detection unit 117 detects a change in the density level between the uniform density member 17 and the background of the document 101 in the main scanning direction and the sub-scanning direction.
As shown in (b) and (c), information on the width and length of the document is detected using a counter. The CPU 37 monitors the counter value detected by the size detection unit 117 at this time, determines the document size, is read at the previous reading position B, and is stored in the first image memory (DRAM). Along with the image data of the first side of the original 101, a SCSI
Output to the external interface via the controller 36. At this time, the second reading unit 111
Although the reading operation of the second side of the original 101 is performed irrespective of the reading mode of only the first side of the original 101, only the size detection by the size detecting unit 117 is performed.
Is not stored in the second image memory (DRAM).

Next, the operation when the mode for reading both sides of a document is selected will be described. The overall flow is the same as in the case of the above-described single-sided reading, except that the width and length of the document 101 are detected by the size detecting unit 117 in the second-side reading unit of the document 101 as described above, and The image data of the second surface of the document 101 read by the second reading unit 111 is stored in the second image memory DRAM under the control of the SiBC 35b. When the CPU 37 determines the size of the document 101 from the data on the width and length of the document 101 detected by the size detection unit 117,
Along with the size information of the document 101, the image data of the first surface of the document 101 stored in the first image memory (DRAM), and the second surface of the document 101 stored in the second image memory (DRAM) Is output to the external interface via the SCSI controller 36.

FIG. 5 schematically shows the operation timing of the image reading apparatus. One side (first side) of the document 101
An outline of the operation timing when the reading mode is designated is as shown in FIG. First, the reading by the first reading unit 103 starts, and the image data of the first surface is stored in the first image memory (DRAM). When the reading of the first surface is completed, the original document continues to be transported as it is, and the reading operation by the second reading unit 111 starts at the previous reading position C. here,
Since the image data of the second side does not need to be transferred, the size detection unit 117 detects the document size. When the document size is detected by the size detection unit 117, the output operation of the image data stored in the first image memory (DRAM) to the external interface is started. On the other hand, the operation timing when the double-sided reading mode of the document 101 is designated is as shown in FIG.

Until the operation of reading the second side of the original 101 by the second reading unit 111 is started, the timing is the same as that of the above-described one-sided original reading. At this time, when the reading operation by the second reading unit 111 is started, the read image data is stored in the second reading unit 111.
It is stored in a second image memory (DRAM) for the surface. When the reading of the second side of the document 101 by the second reading unit 111 is completed, the size of the document is detected by the size detection unit 117, and thereafter, the first image stored in the first image memory (DRAM). Data, second
Original 101 stored in image memory (DRAM)
Are output to the external interface in the order of the image data of the second surface. As shown in FIG. 5, in the image reading apparatus according to the present invention, since the size is detected while the original is being conveyed and the reading operation is performed, an increase in the reading time can be avoided. As described above, in the image reading apparatus according to the present invention, the reading unit on the second side of the document is also used as the document size detecting means, thereby eliminating the need for sensors mounted for document size detection. At the same time, it is possible to realize a double-sided image reading apparatus capable of detecting a wide and fine original size without increasing the reading time.

[0016]

According to the present invention, it is possible to detect the width and length of a document while reading the document image, and to detect a wide range of document sizes without increasing the time required for the reading operation. In addition, it is possible to configure an image reading device capable of reading both sides of a document without causing a significant increase in the size of the device, and to limit the image reading device to a fixed type or an irregular type as long as the prepared image sensor can accept a reading width. Instead, a wide range of document sizes can be detected. Further, an image reading apparatus capable of double-sided reading without causing a large increase in the apparatus size can be configured, and the original size detecting means and the reading means can be used for both purposes. Structure (detection means using multiple photo interrupters)
Becomes unnecessary.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an image reading apparatus embodying the present invention.

FIG. 2 is a functional block diagram of the image reading apparatus shown in FIG.

FIG. 3 is an operation explanatory diagram of the image reading apparatus shown in FIGS. 1 and 2;

FIGS. 4A, 4B and 4C are diagrams showing read output levels of a second reading unit at a reading position C shown in FIG.

FIGS. 5A and 5B are explanatory diagrams of operation timing in the image reading apparatus shown in FIGS. 1 and 2;

[Explanation of symbols]

1: platen glass, 2, 4, 5
... mirror, 3 ... lighting lamp,
6 ... CCD, 7 ... Traveling motor,
8: Document tray, 9: Pickup roller,
DESCRIPTION OF SYMBOLS 10 ... Registration roller pair, 11 ... Convey drum, 12 ... Convey roller, 13
... Conveying roller pair, 14 ... Discharge roller pair, 15 ... Contact image sensor, 1
6 ... RSBU, 17 ... white roller,
18 ... Endorcer unit, 19 ... Endor platen, 20 ... SBU, 21 ... SCU,
23 ... RCU, 24 ... IO
B, 26… Option IP
U, 28 ... main body operation panel, 30 ...
ADU, 35 ... SiBC, 3
6 SCSI controller, 37 CPU
38 ROM, 39 RAM
101: manuscript, 103, 111
... Reading unit, 105 ... White reference plate, 107
... A / D converters, 109, 115 ...
Image processing unit, 113 A / D converter,
117: Document size detecting section

Claims (3)

[Claims] 1. An image reading apparatus that irradiates light from a light source and irradiates a document to be read, photoelectrically converts reflected light or transmitted light thereof, and extracts image information on the document as an electric signal. First reading means for reading one side of the document, second reading means for reading the other side of the document, and the second reading at a reading position by the second reading means. A member having a uniform density disposed on a surface facing the means, and a boundary between the uniform density member and an end of the document is optically detected by the second reading means when reading the document, and the width of the document is detected. An image reading apparatus comprising: a detection unit configured to detect a document length. 2. The image reading apparatus according to claim 1, wherein a contact image sensor is used as said second reading means. 3. The image according to claim 1, wherein said second reading means reads a second side of said document and detects a width and a length of said document. Reader.