JP2000270171A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader whose operations other than image reading are suppressed so as to read an image with a higher efficiency. SOLUTION: In the case that a read section IR generates the image data of an original transported by an original transport section 50 in a copying machine C1, a 1st scanner 11 is moved directly under an original glass plate 513 and a 2nd scanner 14 is also moved to a position corresponding to the position of the 1st scanner 11. In the case that the original transport section 500 continuously transports a plurality of originals, a CCD 16 generates the image data of a density reference board 520 between the originals, and a CPU detects the light distribution at the CCD 16 according to the data. When the degree of the light distribution is high, transport of the originals is once stopped, the 1st scanner 11 is moved up to a position corresponding to a shading board 519, where shading correction processing is executed. When the degree of the light distribution is small, no shading correction processing is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus for generating image data, and more particularly, to a fixed optical system which receives reflected light at a predetermined point of a document moving so as to pass through the predetermined point, The present invention relates to an image reading apparatus including a reference plate provided for detecting the amount of light received by a fixed optical system, wherein the moving document moves between the reference plate and the fixed optical system.

[0002]

2. Description of the Related Art A conventional image reading apparatus includes a reading optical system for reading reflected light from a document as image data as disclosed in Japanese Utility Model Laid-Open No. 4-34060. And a white plate for automatic gain control provided opposite to the reading optical system, so that a document passes between the reading optical system and the white plate. When reading an original image with this image reading apparatus, the reading optical system does not move, and the original moves at a predetermined speed between the reading optical system and the white plate. Thus, the image reading apparatus can read the image of the entire document without moving the reading optical system.

However, in the above-described conventional image reading apparatus, when reading an original image, the white plate for auto gain control directly touches the original, so that the white plate becomes dirty and the reading optical system is shaded. Correction could not be performed correctly. As a result, the image reading apparatus has a disadvantage that the image cannot be read accurately unless the white plate is frequently maintained. That is, the conventional image reading apparatus has a disadvantage that operations other than image reading are frequently required.

On the other hand, a conventional image reading apparatus can read a document image without moving a reading optical system as described above, and can also read a document placed stationary. In some cases, an optical system moves to read a document image. The former has the advantage that the load on the reading optical system in the image reading operation can be reduced, and the latter has the advantage that the image can be read regardless of the form of the original such as a bound original. is there. Therefore,
It is fully conceivable that a single image reading apparatus includes both the former reading optical system and the latter reading optical system.

[0005] However, when both reading optical systems are provided in one image reading apparatus, if a white plate is provided to face one of the reading optical systems as disclosed in the above publication, There were the following inconveniences. That is, in order to perform shading correction on the other reading optical system, it is necessary to move the other reading optical system to a position facing the white plate. That is, if the white plate is provided to face one of the reading optical systems, it takes a long time for shading correction for the other reading optical system, that is, for operations other than image reading. The inconvenience of having occurred.

In order to solve this inconvenience, it is conceivable that the image reading apparatus is provided with a white plate used for shading correction for each of the reading optical systems. That is, it is conceivable that the image reading device includes two white plates. However, if the two reading optical systems perform shading correction using different white plates, there is a new inconvenience that the same image reading apparatus generates image data based on different standards.
Therefore, even if two white plates are provided, new inconveniences occur, and it is considered that the initial inconvenience in the image reading apparatus cannot be sufficiently eliminated.

The present invention has been conceived in view of such circumstances, and has as its object to suppress operations other than image reading.
An object of the present invention is to provide an image reading device that reads an image more efficiently.

[0008]

According to a first aspect of the present invention, there is provided an image reading apparatus for generating image data, wherein the image on a document moving so as to pass a predetermined point. A fixed optical system that receives light reflected at a predetermined point, and a reference plate provided for detecting the amount of light received by the fixed optical system, wherein the document includes the reference plate and the fixed optical system. And the reference plate is provided apart from the moving document.

According to the first aspect of the present invention, the reference plate for detecting the amount of light received by the fixed optical system is provided separately from the moving original.

Thus, it is possible to prevent the reference plate from directly contacting the moving original, so that it is possible to prevent the reference plate from being stained with ink of the original. Therefore, in the image reading apparatus, the maintenance work of the reference plate becomes unnecessary. In addition, the amount of light received by the fixed optical system can be detected more accurately, and the amount of light received by the fixed optical system can be accurately corrected. Therefore, an image reading apparatus that can read an image more accurately can be provided.

According to a second aspect of the present invention, in addition to the configuration of the first aspect of the present invention, the image reading apparatus is provided between the reference plate and the moving original. And a transparent plate body.

According to the second aspect of the present invention, in addition to the operation of the first aspect, a position between the reference plate for detecting the amount of light received by the fixed optical system and the moving original is set. ,
A transparent plate is provided.

According to this, in addition to the effect of the invention described in claim 1, since the plate is transparent, the plate does not hinder detection of the amount of light received by the fixed optical system using the reference plate. Further, it is possible to more reliably prevent the reference plate from directly contacting the moving original by the plate body, and it is possible to more reliably prevent the reference plate from being stained with ink or the like of the original.

An image reading apparatus according to a third aspect of the present invention is an image reading apparatus for generating image data,
Including a fixed optical system that receives reflected light at the predetermined point on the document that moves so as to pass through a predetermined point, and a reference plate provided to detect the amount of light received by the fixed optical system The moving document moves between the reference plate and the fixed optical system, and moves relative to the document placed so as to be stationary, thereby receiving a reflected light from the document. An optical system, a shading correction plate for performing shading correction operation of the movable optical system and the fixed optical system, and a light receiving amount of the fixed optical system detected using the reference plate, A shading correction execution determining unit that determines whether to perform a shading correction operation on the fixed optical system using the shading correction plate.

According to the third aspect of the present invention, the shading correction plate for the fixed optical system is determined by the correction execution determining means based on the amount of light received by the fixed optical system detected using the reference plate. The necessity of the shading correction operation used is determined.

Thus, the shading correction operation of the two optical systems, the fixed optical system and the movable optical system, can be performed using one shading correction plate. Besides,
Since the shading correction operation for the fixed optical system is performed with a minimum necessary based on the amount of light received by the fixed optical system, the image reading device can efficiently generate image data.

According to a fourth aspect of the present invention, in addition to the configuration of the third aspect of the present invention, the fixed optical system includes a plurality of photoelectric conversion elements. The reference plate is configured to detect a plurality of received light amounts in the fixed optical system, and using the reference plate, a received light ratio of a plurality of the photoelectric conversion elements in the fixed optical system. Light-receiving amount ratio detecting means for detecting the shading correction execution determining means, wherein the shading correction execution determining means detects the shading of the fixed optical system when the light-receiving amount ratio detected by the light receiving amount ratio detecting means exceeds a predetermined value. It is characterized in that it is determined to perform a correction operation.

According to the fourth aspect of the present invention, in addition to the effect of the third aspect of the present invention, if the received light ratio at a plurality of locations in the fixed optical system exceeds a predetermined value, shading is performed. A correction operation is performed.

Thus, in addition to the effect according to the third aspect of the present invention, since the shading correction operation for the fixed optical system is performed when necessary, the image reading device can efficiently generate image data. Can be performed.

According to a fifth aspect of the present invention, in the image reading apparatus according to the third or fourth aspect, in addition to the configuration of the image reading apparatus according to the third aspect, the fixed optical system includes a photoelectric conversion element. Wherein the fixed optical system further includes a gain adjusting unit for performing gain adjustment for the conversion of the reflected light into an electric signal, wherein the shading correction execution determining unit detects the light receiving amount ratio detecting unit. If the received light amount ratio is equal to or less than a predetermined value, it is determined that the shading correction operation is not performed and the gain adjustment by the gain adjusting means is performed according to the detected light received amounts at the plurality of locations. And

According to the fifth aspect of the present invention, in addition to the operation of the third or fourth aspect, the light receiving amount ratio at a plurality of locations in the fixed optical system is equal to or less than a predetermined value. If so, the shading correction operation for the fixed optical system is not performed, and the gain is adjusted in the conversion from the reflected light to the electric signal performed by the fixed optical system. That is, when the received light amount of the entire fixed optical system changes uniformly, gain adjustment is performed instead of the shading correction operation.

Thus, in addition to the effects of the third or fourth aspect of the present invention, the shading correction operation, which is an operation for each pixel of the fixed optical system, can be appropriately performed.
Since it is substituted by gain adjustment which is a data correction operation,
In an image reading device, efficiently and more accurately,
Image data can be generated.

According to a sixth aspect of the present invention, in addition to the configuration of the image reading apparatus according to the fourth or fifth aspect of the present invention, a plurality of image reading methods for generating the image data are provided. A mode is configured to be settable, and the predetermined value is changed according to the set mode.

According to the sixth aspect of the present invention, in addition to the operation according to the fourth or fifth aspect, the mode of generating image data according to the mode set in the image reading apparatus is provided. Be changed.

Thus, in addition to the effects of the invention described in claim 4 or claim 5, the image reading apparatus can generate image data according to the user's preference.

According to a seventh aspect of the present invention, in addition to the configuration of the image reading apparatus according to any one of the third to sixth aspects, the fixed optical system is further provided. In order to perform the shading correction operation described above, the optical system further includes an optical system moving means for moving the fixed optical system to a position corresponding to the shading correction plate.

According to the seventh aspect of the present invention, in addition to the operation according to any one of the third to sixth aspects, in the case where a shading correction operation for a fixed optical system is performed. , The fixed optical system is moved to a position corresponding to the shading correction plate.

According to an eighth aspect of the present invention, in addition to the configuration of the image reading apparatus according to any one of the third to seventh aspects, the reference plate further comprises: It is characterized in that it is smaller than the shading correction plate.

According to the eighth aspect of the present invention, in addition to the function of any one of the third to seventh aspects, the reference plate is configured to be smaller than the shading correction plate. .

According to this, in addition to the effect of the invention described in any one of the third to seventh aspects, the amount of material required for forming the reference plate can be reduced, and the lower An inexpensive image reading device can be provided.

[0031]

FIG. 1 shows a first embodiment of the present invention.
FIG. 1 is a diagram showing an overall configuration of a digital copying machine in one embodiment.

Referring to FIG. 1, a copying machine C1 includes a scanning system 10 for reading a document and converting it into an image signal, and an image signal processing unit 20 for processing an image signal sent from the scanning system 10.
A memory unit 30 that stores image data input from the image signal processing unit 20 and outputs the image data to the print processing unit 40, and a print processing unit that drives the semiconductor laser 61 based on the image data output from the memory unit 30 And a laser optical system 60 for guiding a laser beam from a semiconductor laser 61 to an exposure position on a photosensitive drum 71.
An image forming system 70 for developing a latent image by exposure, transferring the image onto recording paper, and fixing the image to form an image; an operation panel (not shown in FIG. 1) provided on the upper surface of the main body of the copying machine C1; The document feeder 500 includes a document feeder 500 that feeds a document and reverses the front and back as necessary, and a finisher 600 that performs processing such as sorting and stapling.

The scanning unit 10 and the image signal processing unit 20 constitute a reading unit IR, and the print processing unit 40, the laser optical system 60, the image forming system 70 and the like constitute a printer unit P. A switch SW1 in the figure is a switch for supplying power to the copying machine C1.

The reading section IR reads an image of a document placed on the document glass 19 and generates image data corresponding to each pixel of the document image. Exposure lamp 1
First scanner 11 having second and first mirror 13a
And a second mirror having second and third mirrors 13b and 13c.
The scanner 14 moves in the directions of arrows b and b '(sub-scanning direction) by driving the scan motor M2.

The light of the exposure lamp 12 is reflected by the original on the original glass 19, and is reflected by mirrors 13a, 13b and 13c.
Then, the light is irradiated onto the CCD 16 via the lens 15. C
CD16 is a direction (main scanning direction) orthogonal to the paper surface of FIG.
A large number of photoelectric conversion elements are arranged in a matrix. For example, an image is read at 400 dpi, and image data corresponding to each pixel is output. In addition, when the above-described scanner unit moves in the directions of the arrows b and b ', the CCD 16 can sub-scan the document image. The sensor SE3 is the first
This is a sensor for detecting that the scanner 11 is at the home position.

The image data output from the CCD 16 is
After being processed by the image signal processing unit 20, it is transmitted to the memory unit 30. The memory unit 30
The image data received from the image signal processing unit 20 is compressed, temporarily stored, decompressed, and transmitted to the printer unit P. At that time, if necessary, a rotation editing process is performed. The image signal processing unit 20 and the memory unit 30 will be described later in detail.

The reading section IR can read an image of a document conveyed on the document glass 513 and generate image data of the document, as described later.

Next, the printer section P will be described. The print processing unit 40 controls the laser optical system 60 based on the image data received from the memory unit 30. The laser optical system 60 includes the print processing unit 40
A semiconductor laser 61 that emits a laser beam modulated (on / off) by the laser, a polygon mirror 62 for scanning the laser beam emitted from the semiconductor laser 61 onto a photosensitive drum 71, and an fθ lens 63
And mirrors 64a and 64b.

Around the photosensitive drum 71 which is driven to rotate, a charging charger 72, a developing device 73, a transfer charger 74, and a separation charger 7 are arranged along the rotation direction.
5, a cleaner 76, and an eraser lamp 77 are arranged to form a toner image by a well-known electrophotographic process and transfer the toner image onto a sheet.

The paper is fed from paper feed cassettes 81a and 81b by paper feed rollers 82a and 82b, and is fed to a transfer charger 74 by a paper transport path and a timing roller 84.

The sheet on which the toner image has been transferred at the position of the transfer charger 74 is discharged from the printer unit P via a transport belt 85, a fixing device 86, a post-fixing roller 87, and a discharge roller 94.

The various rollers and the photosensitive drum 71 are
Driven by the main motor M1. In the vicinity of the paper feed cassettes 81a and 81b, paper size detection sensors SE1 and SE2 for detecting the size of the paper stored in each cassette, and the state of the paper stored in the paper feed cassette (near empty or empty) ) Are provided with sensors 10E and 11E.

A paper detection sensor for detecting the paper conveyance state and timing is disposed in the paper passage path.
By detecting the state of the paper detection sensor, it is possible to detect a paper jam or the like. As a paper detection sensor,
In the present embodiment, a sensor 10P disposed in front of the timing roller, a sensor 11P disposed in the transport belt 85, a sensor 12P disposed in the post-fixing roller 87, and disposed in a discharge unit. Sensor SE9
There are two.

The printer section P has a function of performing switchback conveyance in the case of double-sided copying or the like. The switchback transport mechanism includes a path switching claw 91, a transport roller 92, a reversing roller 93, and the like.

In the one-sided copy mode, the sheet passes through the switchback transport mechanism and passes through the finisher 600.
Or sent to the switchback transport unit for page alignment, switched back and sent to the finisher unit 600.

In the double-sided copy mode, the left end on the path switching claw 91 is moved upward by a solenoid (not shown), and the sheet fed from the roller 87 after fixing reaches the reversing roller 93 through the conveying roller 92. When the trailing edge of the sheet reaches the sheet sensor SE91, the reversing roller 93 is reversed. Thereby, the sheet is sent to the horizontal transport unit.

The fed paper is fed to horizontal transport rollers 88a to 88a.
It is sent to the timing roller 84 through 88c and waits. Here, when a plurality of sheets are continuously fed, the sheets are conveyed one after another at predetermined sheet intervals so as not to overlap each other, and are fed to the finisher 600. Since the paper transport path length is constant, the finisher 600
In addition, the number N of sheets of paper circulated by one of the horizontal transport rollers 88a to 88c (the maximum number of circulating sheets) depends on the sheet size.

The document conveying section 500 includes a multi-sheet document tray 501 for setting a large number of documents, a document insertion detection sensor 515, a document feed roller 502, a document conveying roller pair 503, and a document single feed tray ( (Interruption tray) 504, a document insertion detection sensor 516, a feed roller 505 for a single feed tray, a pair of document feed rollers 506, 507, a pair of document discharge rollers 508, and a pair of document reversing rollers that can be rotated forward and reverse. 510, a pair of original page alignment rollers 509 that can be rotated forward and backward, an original inversion switching claw 511, an original page alignment switching claw 512, and the like.

Reference numeral 513 denotes a document glass set at a position for reading a document set on the document feeder 500.

When a document is set on the multi-sheet document tray 501 on which a large number of documents are set, the copy surface is set upward. When a document is set on the document single feed tray 504, the copy surface is set downward.

When an original is read by the original transport section 500, the first scanner 11 moves to a reading position corresponding to the original glass 513, stops, and the original is transported at a constant speed to read the original information. .

To read only one side of a document set on the multi-sheet document tray 501, the document fed by the document feed roller 502 passes through the document feed roller pair 503 and the document feed roller pair 506. The document is sent to the reading position, passes through a document feed roller pair 507, and is discharged by a document discharge roller pair 508.

At this time, the document inversion switching claw 511 and the document page alignment switching claw 512 are controlled by a solenoid (not shown) so that the document passes through the above-described path.

When reading a document set on the multi-sheet document tray 501 on both sides, first, in order to read the front side, the document fed by the document feed roller 502 is moved to a document feed roller pair 503 and a document feed roller. The document is fed to the document reading position through the pair 506, passes through the document feed roller pair 507, and is operated by the operation of the document reversing switching claw 511 to cause the document reverse roller
Sent to 10. After a predetermined length of original is fed to read the back side, the original reversing roller pair 510 rotates in the reverse direction, and the original is sent to the original feed roller pair 506. Thereafter, the document passes through the document reading position, passes through the document feed roller pair 507, and is sent to the document page matching roller pair 509 by operating the document reversing switching claw 511 and the document page matching switching claw 512. After being fed for a predetermined length, the original page alignment roller pair 509 rotates in the reverse direction,
The document is sent to the document discharge roller pair 508 by the operation of the document page alignment switching claw 512 and discharged. As a result, the pages of the document can be aligned.

When reading the original set on the original single feed tray 504, the original fed by the paper feed roller 505 is sent to the original reading position through the original feed roller pair 506, and the original is fed to the original feed roller. The document is discharged by a document discharge roller pair 508 through the pair 507. At this time, the document reversing switching claw 511 and the document page matching switching claw 512 are controlled by a solenoid (not shown) so that the document passes through the above-described path.

The finisher 600 is mounted on the side of the printer unit P as an additional device for automating processes such as sorting and stapling.

The finisher 600 includes a tray 610 with a storage function for staples and a tray 630 with an elevator function.
, Stapler unit 620, path switching claw 602
And transport rollers 601, 603 to 606 and the like.

When the staple mode is set, the sheet inverted by the switchback function of the printer unit P is discharged from the printer unit P via the discharge roller 94. The sheet sent to the finisher 600 is sent to the transport roller 603 via the transport roller 601 by switching the path switching claw 602.

The path switching claw 602 is controlled by a solenoid (not shown), and switches between sending the sheet to the transport roller 603 and sending the sheet to the transport roller 604 according to the set copy mode. Has become. The sheet discharged from the transport roller 603 is discharged to the tray 610 with a storage function for staples.

After a part of the paper is discharged to the tray 610 with a stapling storage function, the stapler unit 62 is conveyed by the transport roller 607 to perform stapling.
After the sheet is sent to the tray 0 and stapled to a predetermined position, the sheet is discharged to the tray 630 with the elevator function through the conveying rollers 605 and 606.

In a mode other than the staple mode, the paper discharged from the printer unit P is transported by the transport rollers 601, 60.
The sheet is discharged to the tray 630 with the elevator function through 4-606.

FIGS. 2 and 3 show the control unit 1 of the copying machine C1.
FIG. 2 is a block diagram showing a configuration of a 00.

Referring to FIG. 11, control unit 100 controls seven CPs.
U1 to U7, and each of the CPUs 1 to 7 has a ROM 111 to 117 storing a program.
And a RAM 121 serving as a work area for program execution
To 127 are provided. The CPU 3 is provided in the memory unit 30.

CPU 1 controls input and display of signals from various keys on the operation panel.

The CPU 2 controls each part of the image signal processing unit 20 and controls driving of the scanning system 10.

The CPU 4 controls the print processing unit 40, the print optical system 60, and the image forming system 70. The CPU 4 also controls the main motor M1.

The CPU 5 performs a process for adjusting the overall timing of the control unit 100 and setting an operation mode.
A clock IC 118 is connected to the CPU 5 in order to manage the operation time of the copying machine C1 and the like.

The CPU 3 temporarily stores the image data read by controlling the memory unit 30 in a memory (image memory 304), reads out the image data, and outputs it to the print processing unit 40.

The paper size detection sensors SE11, SE1
2 is input to an I / O managed by the CPU 4, and the size of the copy sheet is managed by the CPU 4. Further, the sheet detection sensors 10P, 11P, 12P, and S
The CPU 4 can detect the state of the E92 and the storage paper detection sensors 10E and 11E through the I / O.

CPU 6 controls document transport by document feeder 500. The CPU 7 has a finisher 60
0 is controlled.

Next, the reading section IR and the image signal processing unit 20 will be described. FIG. 4 is a block diagram of the reading unit IR, the image signal processing unit 20, and peripheral parts thereof. Note that the CPU 2, ROM 112, and R in FIG.
The AM 122 and the CCD 16 correspond to those in FIG.

Referring to the figure, a reading unit IR, an image signal processing unit 20 and its peripheral parts include a lens 15 for condensing light from a document MS, a CCD 16 for converting light from the lens 15 to an electric signal, and , Correlated double sampling (C
A DS) unit 23, a gain adjustment unit 25, a clamp adjustment unit 26, an A / D conversion unit 27, a shading correction unit 28 for performing shading correction, an image processing unit 29 for processing and editing image data, An image memory unit 24 for temporarily storing image data, a ROM 112 for storing programs and the like executed by the CPU 2, a RAM 122 as a work area when the CPU 2 executes the programs, and an exposure lamp 12 for irradiating the original MS with light. , Exposure lamp 12
, A thermistor temperature control circuit 12b for controlling the heater 12a, and a dimming inverter 12 for applying a predetermined voltage to the exposure lamp 12.
and a control signal generator 21 for generating a control signal for the accumulation time of the CCD 16.

The control signal generator 21 supplies an image reading synchronization signal to each block shown in FIG. Image memory unit 24
Stores one line of image data according to an instruction from the CPU 2. In addition, the CPU 2 controls each block 22 shown in FIG.
29, control of scanning by driving the scanner motor M2, and control of the entire reading unit IR such as communication with the host CPU.

As described above, the electric signal generated by the CCD 16 based on the light from the lens 15 passes through the blocks 22 to 29 shown in FIG. Device). In the copying machine C1 according to the present embodiment, the amount of light received by the CCD 16 for pixels having the same image density is determined by the change in the light irradiation mode of the exposure lamp 12 and the CCD1.
It is conceivable that it may change due to a change in the light receiving characteristic of 6 itself. Then, in the copying machine C1, a gain adjustment process, a clamp adjustment process, and a shading correction process are executed so that image data more accurately corresponding to the image density is generated. The gain adjustment process is performed by the gain adjustment unit 25, and the clamp adjustment process is performed by the clamp adjustment unit 26.
The shading correction process is performed by the shading correction unit 28.
, Respectively. Hereinafter, the contents of these processes will be described.

First, the gain adjustment processing will be described.
The reflection density data in the electric signal output by the CCD 16 based on the reflected light of the document is generally proportional to the density of the document as shown by a line p or a line q in FIG. Note that the density of the original is the density of the color. For example, in the case of a black-and-white original, the darker the original, the smaller the reflection density data becomes.
The reflection density data has a large value.

Here, regarding a test document on which an image of a predetermined density width is described, the reflection density data obtained by the CCD 16 at a certain point in time is defined as a line p. Also, the copying machine C1
Here, the relationship between ideal reflection density data and the density of the document is represented by a line q. In such a case, the CCD 16
Will be different from the ideal one.

The gain adjustment process is a process executed in such a case. Specifically, reflection density data is obtained by the CCD 16 using a test chart, and this data is compared with ideal data. As a result of the comparison, as shown in FIG. 5, when the inclination of the straight line of the reflection density data with respect to the density of the document is different, a coefficient for correcting the inclination is determined, and the actual coefficient is determined by using the coefficient. The electric signal output from the CCD 16 for the original is corrected. Here, the coefficient determined for correction is called a gain adjustment value.

The "document for test in which an image of a predetermined density width is described" used in the gain adjustment processing.
Can be replaced with a "document having a predetermined image density", that is, a one-color document. For example, when a white document is used as a test document, the reflection density data of the white test document is output to the CCD 16, and the reflection density data is set to the reflection density of the white document on line q. by how much away from D ₁ is a data, it is possible to determine a gain adjustment value.

In the gain adjustment processing according to the present embodiment, when the reading section IR reads an image of a document placed on the document glass 19, the reading section IR
When the document 19 reads an image of a document conveyed by the document conveyance unit 500, the shading plate 519 or a density reference plate 520 described later is used as a "document having a predetermined image density".

Next, the clamp adjustment processing will be described. Referring to FIG. 6, with respect to a test document on which an image having a predetermined density width is described, the reflection density data obtained by CCD 16 at a certain point in time is represented by line p.

In the copying machine C1, the image data created on the basis of the reflection density data is sent to an image forming apparatus such as the printer unit P and printed there. CCD16
Can create reflection density data over a wide density range. On the other hand, in many cases, in an image forming apparatus, when the density of an image becomes higher than a certain density,
Even if the value of the reflection density data changes, the difference in the value of the reflection density data cannot be expressed in the printed image.

Therefore, in the copying machine C1, the density of the image becomes higher than a certain density (B _{1 in} FIG. 6) and the value of the reflection density data becomes lower than a certain value (D _{2 in} FIG. 6). In such a case, a process for uniformly setting the value of the reflection density data to the certain value (D _{2 in} FIG. 6) is performed. This process is called a clamp process. By performing such processing, the range of the value of the reflection density data in the image data sent to the image forming apparatus is not unnecessarily widened. A certain value (D _{2 in} FIG. 6) of the above-mentioned reflection density data is called a clamp adjustment value.

Next, the shading correction processing will be described. As described above, the CCD 16 is configured by arranging a large number of photoelectric conversion elements. When the reflection density data of each pixel in the CCD 16 is obtained for an image of a certain density, the reflection density data of all the pixels should be an ideal value (here, for example, R). In this case, as shown in FIG. 7, the reflection density data of each pixel is different from R.

For this reason, as shown in FIG. 7, in the copying machine C1, reflection density data for an image of a certain density is obtained for all pixels, and the ratio of the reflection density data to the ideal value is calculated for each pixel by the correction coefficient. As, and
A process of multiplying the reflection density data obtained when the image data is actually created by a correction coefficient for each pixel is performed. This processing is called shading correction processing. By performing this processing, it is possible to correct unevenness of illumination, unevenness of transmission of a lens, and unevenness of sensitivity of a sensor.

In the above-described shading correction processing, even when the reading section IR reads an image of a document placed on the document glass 19, it reads a document image conveyed by the document conveying section 500. However, a shading plate (a shading plate 519 described later) is used as the “image of a certain density”. Here, an installation location of the shading plate in the copying machine C1 will be described.

FIG. 8 is a side view of the vicinity of the original glass 19 of the copying machine C1. At the right end of the original glass 19, a scale 518 is provided. The scale 518 covers the upper right end of the original glass 19. The copier C1 is configured so that the right end thereof may be adjusted to the scale 518 when the original MS is set on the original glass 19.

A shading plate 519 is provided between the scale and the upper surface of the original glass 19. CCD
For 16, to obtain a correction coefficient used for the shading correction processing, the first scanner 11 is moved to a position directly below the shading plate 519 to obtain reflection density data. Note that the shading plate 519 can be used as a document having a predetermined image density in the above-described gain adjustment processing.

In the copying machine C1, the original is
There is a case where the document is conveyed and read by the document conveying unit 500 instead of being placed on the top. In this case, the first scanner 1
1 moves to a reading position corresponding to the document glass 513 as shown in FIG. In FIG. 9, the one-dotted dashed arrow indicates the movement path of the document when the image is read. Further, reference numeral 520 in the figure denotes a density reference plate, and reference numeral 521 in the figure denotes a density reference plate support for supporting the density reference plate 520. The application and configuration of the density reference plate 520 will be described below.

In the copying machine C1, the first mirror 13a
Can receive the reflected light of the original. When the original is not sent onto the first scanner, the first mirror 13a can receive the reflected light from the density reference plate 520. That is, when the document is not sent to the first scanner 13a, the CCD 16 can generate reflection density data for the density reference plate 520.

The three density reference plates 520 are provided, each of which is constituted by a white plate. FIG. 10 shows a bottom view of the density reference plate support 521 and the density reference plate 520. Each density reference plate 520 includes a density reference plate support 521.
The surface facing the first scanner 11 and the CCD 16
Are provided near the center and both ends of the readable range in the main scanning direction. The direction in which the three density reference plates 520 are arranged in the density reference plate support 521 is the same as the direction in which the photoelectric conversion elements in the CCD 16 are arranged. Thus, when the document is not sent to the first scanner 13a, the CCD 16 can generate the reflection density data of the density reference plate 520 for the photoelectric conversion elements arranged at the center and both ends.

Each density reference plate 520 is provided for the following reasons.
It is considered that a size of about 10 mm square is enough. That is, the density reference plate 520 is used for adjusting the gain of the CCD 16 and detecting the light distribution ratio, as described later. At this time, each density reference plate 520 is a CCD
The reflection density data is generated by the photoelectric conversion elements at the center and both ends of 16. The size of each density reference plate 520 is such that the average value of the reflection density data generated for the center, right end, and left end of the CCD 16 can be calculated, for example, 4 × 4 = 16 for each of the center and both ends. It is sufficient that reflection density data of about a pixel can be generated. And the size corresponding to one pixel is
400 dpi is 1 mm square, and 600 dpi is 0.67 mm square. Therefore, it is sufficient that the size of each density reference plate 520 is about 10 mm square.

Each density reference plate 520 is provided so as to have a gap between it and the moving original (the one-dotted dotted arrow in FIG. 9). This can prevent the ink of the moving document from adhering to the density reference plate 520.

In order to more reliably prevent the ink of the original from adhering to the density reference plate 520, it is necessary to use FIG.
It is preferable that a transparent glass body 520a be provided between the density reference plate 520 and the moving document as shown in FIG.
In this embodiment, since the glass body 520a is provided as a cover so as to be in close contact with the density reference plate 520, it is possible to reliably prevent dust and the like from adhering to the density reference plate 520, and Dust etc. are glass body 520a
Even if adhered to, it can be easily removed.

Next, the document of the CPU 2 is transferred to the document conveying section 50.
The processing contents of the processing of reading at 0 (EDH reading processing) will be described. FIG. 12 is a flowchart of the EDH reading process of the CPU 2.

Referring to FIG. 12, in copying machine C1, E
When the operation for executing the DH reading process is performed, first, C
PU2 performs the process of turning on the exposure lamp 12 in S101, and proceeds to S102.

In S102, the CPU 2 moves the first scanner 11 to just below the shading plate 519 as described with reference to FIG. 8, and proceeds to S103.

In S103, the CPU 2 performs the above-described gain adjustment processing, and proceeds to S104. Note that S103
As described later, the CPU 2 monitors the reflection density data of the shading plate 519 and appropriately sets a gain adjustment value and a correction coefficient in shading correction for each pixel, as described later.

In S104, the CPU 2 performs a clamp adjustment process for setting a clamp adjustment value for the reflection density data monitored in S103, and proceeds to S105.

In S105, the CPU 2 extracts three pieces of reflection density data corresponding to the density reference plate 520 from the reflection density data monitored in S103, stores them as reference values, and proceeds to S106.

In S106, the first scanner 11 is moved to FIG.
As shown in (2), the document is moved to the reading position corresponding to the document glass 513, the document is set to be subjected to shading correction processing on image data to be generated from now on, and the document transport unit 500 starts transporting the document. Then, the process proceeds to S107.

In S107, the first scanner 11, CCD
In step S10, the reading unit IR including the document 16 reads an image of the document conveyed on the document glass 513.
Proceed to 8.

In S108, the original glass 513
At 07, it is determined whether or not the rear end of the document being read has arrived. If it is determined that the rear end has reached, the process proceeds to S109.

In S109, it is determined whether or not the next original has been set in original transport section 500. If it is determined that the next original has not been set, the process proceeds to S110.

In S110, the exposure lamp 12 is turned off,
The setting for canceling the execution of the shading correction processing is performed, and the EDH reading processing ends.

On the other hand, if it is determined in S109 that the next original has been set in the original transport section 500, the flow advances to S111.

In S111, the setting of the gain adjustment value in S103 is released, and the three density reference plates 5
20 is generated, and furthermore, the generated reflection density data is stored in blocks 22 to 22, respectively.
28 and via the image memory unit 24, and S105
A process of calculating the ratio with the reference value stored in step S1 is performed, and
Proceed to 12. Since S111 is executed from the time when it is determined in S108 that the rear end of the original has reached the original glass 513 to the time when the next original is conveyed onto the original glass 513, in S111, the CCD 16 is set to the density reference. The reflection density data for the plate 520 can be generated.

In S112, a process for setting an optimum gain adjustment value is performed again based on the ratio calculated in S111, and the process proceeds to S113. Note that the data generated in S111 is for the density reference plate 520, and the reference values stored in S105 are for the shading plate 519. On the other hand, in the copying machine C1, the density reference plate 520 is a shading plate 519.
Since the distance to the exposure lamp 12 is longer than that of the exposure lamp 12, the amount of light received from the exposure lamp 12 is reduced. Therefore, S
In 112, the gain adjustment value is set based on the ratio calculated in S111 as described above. However, in setting this gain adjustment value, it is necessary to consider the difference in the amount of light received from the exposure lamp 12 described above. is there.

In S113, a process of calculating the ratio of the reflection density data of the three density reference plates 520 taken in S111 as a light distribution ratio and comparing it with a predetermined value is performed. If the light distribution ratio is equal to or less than the predetermined value, the process proceeds to S107, and if the light distribution ratio exceeds the predetermined value, the process proceeds to S114.
Proceed to.

In S114, a process for stopping the conveyance of the original to the original conveying section 500 is performed, and the process proceeds to S102.

In other words, in the EDH reading process described above, when images of a plurality of originals are continuously read, the CCD 16 sets the reflection density of the density reference plate 520 between the continuously transported originals. Data is generated, and the gain adjustment value is reset based on the data. Further, based on the data, a light distribution ratio in light reception at the time of data generation of the CCD 16 is calculated. If the light distribution ratio is equal to or less than the predetermined value, the image reading is continued as it is,
If the light distribution ratio exceeds a predetermined value, the first scanner 11 moves to a position corresponding to the shading plate 519, and a gain adjustment value, a clamp adjustment value, and a correction coefficient in the shading correction processing are newly set.

In the EDH reading process of the present embodiment,
Since the CCD 16 generates the reflection density data for the density reference plate 520 between the continuously conveyed documents and the gain adjustment value is appropriately set based on the data, the reading unit IR always sets the optimal value. Image data can be generated. The light distribution ratio in the light reception of the CCD 16 is calculated using the data, and only when the light distribution ratio exceeds a predetermined value, the image reading of the document to be continuously performed is temporarily stopped. One scanner 11 is moved to a position corresponding to the shading plate 519, and a process of setting a gain adjustment value, a clamp adjustment value, and a correction coefficient in the shading correction process is performed again. As a result, the reading unit IR can always generate optimal image data without stopping image reading of a document as much as possible, that is, while generating image data more efficiently.

In the present embodiment, the setting of the correction coefficient in the shading correction processing is performed regardless of whether the original for which the image data is generated is placed on the original glass 19 or conveyed by the original conveying unit 500. , Using a shading plate 519. As a result, in any case, the shading correction processing is performed in the same manner, and in any case, the image data is generated based on the same reference with respect to the document density.

In this embodiment, the reference density plate 5
20 is not used for the shading correction processing, so that it is not necessary to have an area corresponding to all the pixels of the CCD 16, and as shown in FIG. 10, three white plates having an area of 1 mm square are used. Can be configured.

It is not necessary to always generate data on the density reference plate 520 of the CCD 16 between originals. For example, the data may be generated each time a document is conveyed on the document glass 513 by an appropriate number of two or more.

If the copying machine C1 is configured so that the user can set the mode of the image data generation mode, the predetermined value serving as the criterion for the determination in S113 is set. It can be configured to be changed according to the changed mode. For example,
In the copying machine C1, a "normal document mode" is a mode for generating image data of a normal document, or a mode for generating image data of a document having a halftone (intermediate color) portion such as a photograph. It is possible that one of the "photo modes" can be set. In such a case, when the "normal document mode" is set, the predetermined value of the copying machine C1 is "0.5", and when the "photo mode" is set, the predetermined value is "0.7". It can be configured as follows.

The arrangement of the density reference plate 520 on the density reference plate support 521 is preferably set in consideration of the following. That is, as shown in FIG. 10, the three density reference plates 520 are provided near the center and both ends of the reading range of the CCD 16 in the main scanning direction. CCD
The portion where the amount of received light at 16 is maximum is preferable, and the portion near both ends is preferably the portion where the amount of received light is minimum.

Next, the content of the gain adjustment processing in S103 will be described in detail. FIG. 13 shows a flowchart of a subroutine of the gain adjustment processing.

Referring to FIG. 13, in the gain adjustment process, CPU 2 first performs a process of setting the gain adjustment value to a predetermined value and canceling the execution of the shading correction process in S1031. Proceed to S1032. In S1032, it is determined whether or not the first scanner 11 is at a position corresponding to the shading plate 519. If it is determined that the first scanner 11 is at the position, the process proceeds to S1033. S103
In 3, the CPU 2 causes the CCD 16 to generate the reflection density data on the shading plate 519 for all the pixels, monitors the reflection density data, and proceeds to S1034. More specifically, the CCD 16 generates an electric signal including the reflection density data. The electric signal is subjected to predetermined processing in blocks 22 to 28 shown in FIG. 4 and then input to the CPU 2 via the image memory unit 24. Is done.

Then, the CPU 2 determines in S1034 that S1
033, based on the reflection density data monitored
A process for determining and setting the gain adjustment value is performed, and S1
Proceed to 035.

In S1035, the CPU 2 determines in S1033
The processing for setting the correction coefficient in the shading correction is performed based on the reflection density data monitored in step, and the gain adjustment processing ends.

The above-described gain adjustment processing can be substituted by adjusting the light amount of the exposure lamp 12 using the dimming inverter 12c. If the effect of the gain adjustment process is obtained by adjusting the light amount of the exposure lamp 12, the adjustment of the light amount requires a longer time than the gain adjustment process. Sometimes it is necessary to do this.

In the present embodiment described above, the copying machine C
One reading unit IR constitutes an image reading device that generates image data. The scanning system 1 when the first scanner 11 is located at a position corresponding to the original glass 513 (when an image is read in the EDH reading process).
0 forms a fixed optical system that receives the reflected light at the predetermined point on the document that moves so as to pass through the predetermined point. The density reference plate 520 constitutes a reference plate provided for detecting the amount of light received by the fixed optical system. Then, as shown in FIG. 9, the density reference plate 520 is arranged so as to have a gap between the density reference plate 520 and the document conveyed on the document glass 513,
It is disclosed that the reference plate is provided apart from the moving document.

Further, in the present embodiment described above, the transparent plate provided between the reference plate and the moving document is constituted by the glass body 520a.

In the present embodiment described above, the scanning system 10 for reading an image of a document placed on the document glass 19 moves the document placed stationary so as to move. Thus, a movable optical system that receives the reflected light from the original is configured. Further, the shading plate 519 constitutes a shading correction plate for performing a shading correction operation of the movable optical system and the fixed optical system. And S1 of FIG.
In 13, the CPU 2 compares the light distribution ratio with a predetermined value, and determines whether to return to S102 according to the result of the comparison.
A shading correction execution determining means for determining whether or not to perform a shading correction operation on the fixed optical system using the shading correction plate in accordance with the amount of light received on the fixed optical system detected using the reference plate. Is configured.

In the present embodiment described above, C
The CD 16 generates an electric signal from the reflected light,
It is disclosed that the fixed optical system converts reflected light received by the fixed optical system into an electric signal. The gain adjustment unit 25 that performs the gain adjustment process and the CPU 2 that controls the gain adjustment process constitute a gain adjustment unit that performs gain adjustment for conversion of reflected light into an electric signal by the fixed optical system. I have.

The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a copying machine according to one embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a control unit of the copying machine shown in FIG.

FIG. 3 is a block diagram following FIG. 2;

FIG. 4 is a block diagram of a reading unit, an image signal processing unit, and peripheral parts of the copying machine of FIG. 1;

FIG. 5 is a diagram for explaining a gain adjustment process in the copying machine of FIG. 1;

FIG. 6 is a diagram for explaining a clamp adjustment process in the copying machine of FIG. 1;

FIG. 7 is a diagram for explaining shading correction processing in the copying machine of FIG. 1;

FIG. 8 is a diagram for explaining an installation location of a shading plate in the copying machine of FIG. 1;

FIG. 9 is a diagram for explaining a positional relationship of components around a density reference plate in the copying machine of FIG. 1;

FIG. 10 is a bottom view of a density reference plate and a density reference plate support in the copying machine of FIG. 1;

11 is a diagram showing a modification of the components around the density reference plate in the copying machine shown in FIG. 1;

FIG. 12 is a flowchart of a process (EDH reading process) of reading a document by a document transport unit of the CPU in the copying machine of FIG.

FIG. 13 is a flowchart of a subroutine of a gain adjustment process in FIG. 12;

[Explanation of symbols]

 C1 Copier 11 First scanner 12 Exposure lamp 16 CCD 19,513 Original glass 25 Gain adjuster 26 Clamp adjuster 500 Original transporter 519 Shading plate 520 Density reference plate 520a Glass body

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/401 H04N 1/40 101A F-term (Reference) 2H027 DA23 DB01 DB03 DC03 DC12 DC19 DE02 DE07 DE10 EA02 EC06 EC07 ED11 ED16 ED17 ED21 ED29 FA12 FA13 FA16 FA18 FA20 FA21 FA22 FA23 FD08 2H076 AA04 AA07 AB05 AB12 BA16 BA20 BA24 BA42 BB06 DA05 DA08 5C072 AA01 BA05 BA08 CA14 EA05 FB12 LA02 LA15 NA01 RA16 MM02 UA05 UA05 UA05 UA05 UA05 PQ08 PQ12 PQ20 RR01 RR12 SS01 SS03 TT06

Claims (8)

[Claims] 1. An image reading apparatus for generating image data, comprising: a fixed optical system receiving reflected light at a predetermined point on a document moving so as to pass through a predetermined point; A reference plate provided to detect the amount of light received by the system, wherein the document moves between the reference plate and the fixed optical system, and the reference plate is separated from the moving document. An image reading device provided. 2. The image reading apparatus according to claim 1, further comprising a transparent plate provided between said reference plate and said moving document. 3. An image reading apparatus for generating image data, comprising: a fixed optical system receiving reflected light at a predetermined point on a document moving so as to pass through a predetermined point; A reference plate provided for detecting the amount of light received by the system, wherein the moving document is moved between the reference plate and the fixed optical system, and is placed on a document placed so as to be stationary. A movable optical system that receives reflected light from the document by moving with respect to the original; a shading correction plate for performing shading correction operation of the movable optical system and the fixed optical system; and the reference plate. Shading for determining whether or not to perform a shading correction operation on the fixed optical system using the shading correction plate according to the amount of received light on the fixed optical system detected by An image reading apparatus, comprising: a correction execution determining unit. 4. The fixed optical system includes a plurality of photoelectric conversion elements, the reference plate is configured to detect a plurality of received light amounts in the fixed optical system, and uses the reference plate. And a light-receiving amount ratio detecting means for detecting a light-receiving amount ratio of the plurality of photoelectric conversion elements in the fixed optical system, wherein the shading correction execution determining means detects the light receiving amount detected by the light-receiving amount ratio detecting means. 4. The image reading apparatus according to claim 3, wherein when the amount ratio exceeds a predetermined value, it is determined that a shading correction operation is performed on the fixed optical system. 5. The fixed optical system includes a photoelectric conversion element, and further includes a gain adjusting unit that performs gain adjustment on conversion of the reflected light into an electric signal by the fixed optical system. Shading correction execution determining means, if the received light amount ratio detected by the received light amount ratio detecting means is equal to or less than a predetermined value, does not perform the shading correction operation, The image reading device according to claim 3, wherein the image reading device determines to perform gain adjustment by the gain adjusting unit. 6. The image processing apparatus according to claim 4, wherein a plurality of modes for generating the image data are configured to be settable, and the predetermined value is changed according to the set mode. Image reading device. 7. An optical system moving means for moving the fixed optical system to a position corresponding to the shading correction plate in order to perform a shading correction operation on the fixed optical system. The image reading device according to claim 6. 8. The image reading apparatus according to claim 3, wherein the reference plate is smaller than the shading correction plate.