JP2001352447A - Image-forming device, image-forming method, and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image-forming device that can extend the service life of a light source, while maintaining proper shading correction accuracy. SOLUTION: In the image-forming device, having a shading correction function that applies shading correction to original image data read by a read section, which reads an original by applying photoelectric conversion to an optical image obtained by optical scanning of the original, through the use of white board data obtained by optical scanning of a white board by the read section, the white board data read by the read section is compared with a reference value and it is discriminated whether a width of a magnification rate of the white board data is changed over and the width of the magnification rate is changed over when the white board data is magnified, on the basis of the discrimination result, depending on whether at least the original of a read object is a color original or a black/white original or whether at least an image priority mode or a character priority mode is set.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a shading correction technique in an image reading apparatus or the like using an image sensor (imaging element) such as a CCD sensor.

[0002]

2. Description of the Related Art Generally, in an image forming apparatus such as a copying machine,
In image data obtained from an image sensor such as a CCD sensor, density level unevenness (shading) occurs due to variations in the characteristics of the image sensor, the amount of light incident on the image sensor, lens aberrations, and contamination of the glass surface of the platen glass. Therefore, shading correction processing is performed.

Conventionally, in this shading correction, a white correction plate is usually provided at a predetermined position, and the white correction plate is irradiated with light from a light source in the same manner as when reading a document, and the reflected light is incident on an image sensor. The data obtained from the image sensor is used as white reference data for shading correction. Then, a shading correction coefficient is calculated from the ratio between the white reference data and the shading target value,
When an actual document image is read, shading correction is performed by multiplying the shading correction coefficient by data of a pixel corresponding to each document image data.

[0004]

As a technique for extending the life of the light source by using a melting point, it is conceivable to suppress the light amount of the light source as much as possible. However, if the shading correction accuracy is reduced by suppressing the light amount of the light source, an image with poor shading correction accuracy is always output.

The present invention has been made under such a background, and an object thereof is to extend the life of a light source while maintaining good shading correction accuracy.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method for converting an optical image obtained by optically scanning a document into a document by reading a document by photoelectric conversion. On the other hand, in an image forming apparatus having a shading correction function of performing shading correction using reference image data obtained by optically scanning a reference image by the reading unit, according to the type of a document to be read,
A determining unit that compares the reference image data read by the reading unit with a reference value to determine whether to change the width of the magnification ratio of the reference image data, and based on at least a determination result by the determining unit Gain range switching means for switching the width of the scaling factor when scaling the reference image data.

Further, according to the present invention, an optical image obtained by optically scanning a document is photoelectrically converted, and a reference image is read by the reading unit with respect to document image data read by a reading unit which reads the document. In an image forming apparatus having a shading correction function of performing shading correction by using reference image data obtained by scanning, according to a mode, the reference image data read by the reading unit is compared with a reference value. Determining means for determining whether to change the width of the magnification of the reference image data; and a gain range for switching the width of the magnification when the reference image data is changed based on at least the result of the determination by the determination means. Switching means is provided.

Further, according to the present invention, an optical image obtained by optically scanning an original is photoelectrically converted, and a reference image is read by the reading unit with respect to the original image data read by the reading unit which reads the original. In an image forming method applied to an image forming apparatus having a shading correction function of performing shading correction by using reference image data obtained by scanning, according to a type of a document to be read, the image is read by the reading unit. The reference image data is compared with a reference value to determine whether to change the width of the magnification of the reference image data, and based on the determination result, the magnification of the reference image data when the magnification is changed is determined. The width is changed.

Further, according to the present invention, an optical image obtained by optically scanning a document is photoelectrically converted, and a reference image is read by the reading unit with respect to document image data read by a reading unit which reads the document. In an image forming method applied to an image forming apparatus having a shading correction function of performing shading correction by using reference image data obtained by scanning, the reference image data read by the reading unit according to a mode. A comparison is made with a reference value to determine whether to change the width of the magnification ratio of the reference image data. Based on the determination result, the width of the magnification ratio when the reference image data is changed is switched. ing.

Further, according to the present invention, an optical image obtained by optically scanning a document is photoelectrically converted, and a reference image is read by the reading unit with respect to document image data read by a reading unit which reads the document. In a computer-readable medium applicable to an image forming apparatus having a shading correction function of performing shading correction by using reference image data obtained by scanning, the reading unit may be used in accordance with a type of a document to be read. By comparing the read reference image data with the reference value, it is determined whether or not the width of the magnification of the reference image data should be switched. Based on the determination result, the magnification when the reference image data is scaled is determined. It has the content of switching the width of the magnification.

Further, according to the present invention, an optical image obtained by optically scanning an original is photoelectrically converted, and the original image data read by the reading unit for reading the original is converted into a reference image by the reading unit. In a computer-readable medium applicable to an image forming apparatus having a shading correction function of performing shading correction by using reference image data obtained by scanning, a reference image read by a reading unit according to a mode according to a mode. The data and the reference value are compared to determine whether to change the width of the magnification of the reference image data. Based on the determination result, the width of the magnification when the reference image data is changed is switched. Have content.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

[Overall Configuration] FIG. 1 is a schematic diagram showing the overall configuration of a color copying apparatus to which an image forming apparatus according to an embodiment of the present invention is applied. In FIG. 1, reference numeral 101 denotes a reader unit. The reader unit 101 includes a document table 102, a light source 103, a photoelectric conversion element 104, an A / D converter 105,
It has a mirror group 106. The light source 103 irradiates a document placed on the document table 102 with light while controlling the movement thereof, and reflected light reflecting the document image is reflected by the mirror group 1.
At 06, the light enters a photoelectric conversion element 104 such as a CCD. The photoelectric conversion element 104 photoelectrically converts the incident light and outputs the converted light as analog image data. The A / D converter 105 converts the analog image data output from the photoelectric conversion element 104 into digital image data. Convert.

Reference numeral 2001 denotes a printer unit. The printer unit 2001 has a printer engine 2002, an engine control unit 2003, a reader control unit 2004, a printer control unit 2005, and an option control unit 2006. The printer unit 2001 can optionally include a paper cassette 2101 and a sorter 2102, and can also be connected to a host computer 2103 to print an image input from the host computer 2103. is there.

The printer engine 2002 performs an actual printing operation under the control of the engine control unit 2003.
A reader control unit 2004 controls an image signal processing unit 902 (see FIG. 9) that performs predetermined processing on digital image data output from the A / D converter 105, and a motor driver for controlling movement of the light source 103. (Not shown), and also controls communication with the engine control unit 2003 and the printer control unit 2005. That is, in the present embodiment, by disposing the reader control unit 2004 in the printer unit 2001, an external cable for controlling communication with the engine control unit 2003 and the printer control unit 2005 is not required. .

[Basic System Configuration] In the present embodiment, as described above, the reader control unit 2004 is connected between the printer control unit 2005 and the engine control unit 2003,
The reader control unit 2004 controls the printer control unit 20.
And communication control between the engine control unit 2003 and the engine control unit 2003. Here, first, a basic system configuration as a premise thereof will be described.

FIG. 2 is a diagram showing a basic system configuration when a reader control unit 2004 is not interposed between the printer control unit 2005 and the engine control unit 2003. FIG. 3 shows the basic system of FIG. Applied printing device 3001
FIG. 2 is a schematic diagram showing the overall configuration of the embodiment.

A video interface 2104 shown in FIGS.
And the engine control unit 2003 and the printer control unit 20
05 is performed. This video I / F
Details of signals transmitted and received via 2104 will be described later.

A printer control unit 2005 is connected to a directly connected host computer 2103 or network 2
The data to be printed sent from the host computer 2103 via the host computer 105 is received. This data includes bitmap data and PDL (Page Des
It is sent in various data formats, such as data described in the “Cription Language”. Therefore, the printer control unit 2005 develops the received data to be printed into a memory as raster image data in the memory, and transmits the received data to the engine control unit 20 via the video I / F 2104.
Transfer to 03.

The engine control unit 2003 forms a toner image based on the received image data, transfers the toner image to recording paper, fixes the toner image on the recording paper, and discharges the paper. The details of the image forming process in the engine control unit 2003 will be described later. In order to realize these image forming sequences, the engine control unit 2003
Various types of loads are controlled, and the printer engine 200 is controlled.
2 is detected and notified to the printer control unit 2005. Thus, the host computer 2103
Can be printed out.

Next, under the basic system configuration shown in FIG. 2, the printer control unit 2005 and the engine control unit 20
Signals transmitted to and received from H.03 will be described in detail with reference to FIGS. Although various signals as shown in FIG. 5 are exchanged between the printer control unit 2005 and the engine control unit 2003, only the typical signals shown in FIG. 4 will be described here.

First, a PPRDY (printer power ready) signal 203 indicates that after the power has been supplied to the engine control unit 2003 and processing such as initialization has been completed, communication with the printer control unit 2005 has become possible. Is a signal indicating the following. A CPRDY (controller power ready) signal 204 is supplied to the printer control unit 2005,
After the processing such as the initial setting is completed, the engine control unit 200
3 is a signal indicating that communication has become possible.

An RDY (ready) signal 205 is a signal indicating that the printing operation has been enabled, and in response to a print start instruction signal [PRNT (print) signal] 206 from the printer control unit 2005, an engine control unit 20
Reference numeral 03 denotes a signal output to the printer control unit 2005.
The RDY signal 205 indicates that the temperature inside the fixing unit in the printer engine 2002 has reached a predetermined temperature, the recording paper is not remaining in the printer, or the polygon mirror is rotating at a predetermined speed. It becomes “true” when each part of 2002 is operating normally. The PRNT signal 206 instructs the continuation of the printing operation in addition to the start of the printing operation.

TOP (top of page) signal 207
Is a synchronization signal serving as a reference for vertical scanning of an image, and is output from the engine control unit 2003 to the printer control unit 2005. This TOP signal 207 is the PRINT signal 20
6 is output from the printer control unit 2005 and is output after a predetermined time. LSYNC (line synchronization) signal 20
Reference numeral 8 denotes a synchronization signal used as a reference for horizontal scanning by the printer control unit 2005.
After the T signal 206 is output from the printer control unit 2005, it is output after a predetermined time.

VCLK (video clock) signal 209
Is a VDOEN (image enable) signal 21 described later.
0, a synchronous clock signal for the VDO (image) signal 211, which has a frequency corresponding to the image signal. V
The DOEN signal 210 is a signal for performing capture control when the image signal output from the printer control unit 2005 is captured by the ethidine control unit 2003. Engine control unit 2
003 is synchronized with the VCLK signal 209 and
Detecting whether the EN signal 210 is true or false;
In the case of "true", the image signal is captured, and in the case of "false", the capture is not performed. The VDO signal 211 is image data, and the printer control unit 2005 sends the TOP signal 207 in the vertical direction and the LS signal in the horizontal direction.
The VDO signal 211 is output in synchronization with the VCLK signal 209 based on the YNC signal 208.

CCLK (controller clock) signal 2
Reference numeral 12 denotes synchronization when the printer control unit 2005 transmits a serial command to the engine control unit 2003 and when the engine control unit 2003 transmits a serial status signal to the printer control unit 2005 in response to the serial command. A clock signal, and a printer control unit 2
005. A CBSY (command busy) signal 213 is a signal indicating to the engine control unit 2003 that the printer control unit 2005 is transmitting a serial command using a CMD (command) signal 214 described later. The CMD signal 214 is transmitted to the printer control unit 200.
Reference numeral 5 denotes a signal used when transmitting a serial command to the engine control unit 2003.

SBSY (status busy) signal 215
Is a signal indicating to the printer control unit 2005 that the engine control unit 2003 returns a serial status signal using an STS (status) signal 216 described later. The STS signal 216 is output from the engine control unit 200.
Reference numeral 3 denotes a signal used when a serial status signal is returned to the printer control unit 2005. CCRT
(Status change notification) signal 217
02 when the status of the printer controller 200 changes
5 is a signal to be reported. When receiving the CCRT signal 217, the printer control unit 2005 issues a command for inquiring what state of the printer engine 2002 has changed using the CMD signal 214, and in response, the engine control unit 2003 issues the STS signal 216.
Respond using.

The above signals may be referred to as signal lines in the following description.

Next, the overall mechanical configuration of the printer engine 2002 controlled by the engine control unit 2003 will be described with reference to FIG.

In FIG. 6, a photosensitive member scanner 401 is
By generating a laser beam corresponding to an image signal (VDO signal 211) sent from the printer control unit 2005 via the engine control unit 2003, and irradiating the photoconductor drum 402 via a polygon mirror (not shown), Then, an electrostatic latent image is formed on the photosensitive drum 405. The photosensitive drum 402 sequentially counters the electrostatic latent image with the color developing device 403 and the black developing device 404 while rotating counterclockwise. The color developing device 403 and the black developing device 404 develop the electrostatic latent image by attaching toner to the photosensitive drum 402 according to the electrostatic latent image formed on the photosensitive drum 402. In the case of a black and white image, only the black developing device 404 operates,
In the case of a color image, a color developing unit 403 and a black developing unit 404
Both work.

Next, the toner image generated on the photosensitive drum 402 is transferred to the intermediate transfer member 405 rotating clockwise.
Is transferred to This intermediate transfer member 405 completes one intermediate transfer by rotating once for a black-and-white image and four times for a color image. In parallel with such an operation, the recording paper conveyed from the upper cassette 408 or the lower cassette 409 by the pickup roller 411 or 412 is transported by the paper feed roller 413 or 414, and the registration roller is transported by the transport roller 415. It is transported to 416.

The registration roller 416 sends the recording paper between the intermediate transfer member 405 and the transfer belt 406 at the timing when the transfer on the intermediate transfer member 405 is completed.
Then, the transfer belt 406 rises so as to contact the intermediate transfer body 405 when the recording paper reaches, and the intermediate transfer body 40
5 is transferred to the recording paper. The image transferred to the recording paper is fixed on the recording paper by a heating process and a pressure process by the fixing roller 407. The recording paper on which the image has been fixed is discharged from either the face-up discharge port 717 or the face-down discharge port 418 designated by the printer control unit 2005 in advance.

Next, the timing of signals transmitted and received between the printer control unit 2005 and the engine control unit 2003 will be described with reference to the timing chart of FIG. This timing chart shows the various signals described above as time elapses.

First, when the preparation of the image information is completed, the printer control unit 2005 sets the PRNT signal to Low (true) and transmits the signal to the engine control unit 2003. At the same time,
An image synchronization signal (VCLK signal) used for transferring the image signal is also generated. In response, the engine control unit 200
Reference numeral 3 performs various settings in the printer engine 2002 and outputs a TOP signal and an LSYNC signal to the printer control unit 2005 when an image can be received. In accordance with the vertical synchronizing signal (TOP signal) and the horizontal synchronizing signal (LSYNC signal), the printer control unit 2005 transfers an image signal (VDO signal) and a VDOEN signal as an image valid signal to the engine control unit 2003. I do.

Next, a description will be given of what commands and statuses are transmitted and received by serial communication during these printing operations. FIG. 8 shows the printer control unit 2005.
9 shows the timing of serial communication between the control unit and the engine control unit 2003.

First, the case where the lowermost CCRT signal in FIG. 8 is not used will be described. When the printer control unit 2005 wants to issue a command to the engine control unit 2003, the CBSY signal is set to Low (true) and transmitted as a CMD signal in synchronization with a clock signal (CCLK signal). Engine control unit 2003 receiving these signals
After confirming that the CBSY signal is High (false), it sets the SBSY signal to Low (true), and outputs status data of the printer engine 2002 corresponding to the command to the CCL generated from the printer control unit 2005.
It is sent as an STS signal in synchronization with the K signal. The printer control unit 2005 continues or interrupts the print control based on the received status data.

Next, the CCRT signal will be described. The CCRT signal is a signal that becomes Low (true) when a change occurs in the state of the printer engine 2002 specified by the printer control unit 2005 in advance. For example, suppose that the printer control unit 2005 has previously set a CMD signal so that the CCRT signal is made valid when a recording paper empty state occurs. In this case, if the printer control unit 2005 requests two printouts in a state where only one recording sheet remains, the print sequence operation for the first sheet is normally processed without any problem. However, since the second recording sheet does not exist, the engine control unit 2 starts the image forming process for the second sheet.
The 003 side detects a change in the state and outputs the CCRT signal to Hig.
Change from h (false) to Low (true).

When the printer control unit 2005 detects that the CCRT signal has changed to low (true), the printer control unit 2005 sends the recording paper to the engine control unit 2003 in order to know which paper cassette has no recording paper. Issues a command requesting the presence status. In response to the request command, the engine control unit 2003 returns the status of the paperless cassette to the printer control unit 2005. CCR
As for the T signal, the SBSY signal for which the status is returned is Low.
It is cleared to High at the timing of becoming.

Next, the flow of command / status exchange actually performed between the printer control unit 2005 and the engine control unit 2003 during a printing operation will be described with reference to the sequence diagram of FIG. Here, color output is assumed.

When a print start request is issued, the printer control unit 2005 inquires the engine control unit 2003 of the ready state of the printer engine 2002 while performing image data conversion processing and the like. Next, a command for designating the recording paper cassette is issued, and further a command for requesting the size information of the recording paper stored in the designated recording paper cassette is issued. In response to these series of commands, the engine control unit 2003 returns a corresponding status.

Next, the printer control unit 2005 sequentially issues a command for designating a paper discharge port and a page mode designation command for designating how many pages (how many copies) the same image is formed. Finally, by issuing a command specifying monochrome / color, the engine control unit 2003
End all the settings related to. After that, a print request signal (PRNT signal 206) is issued to the engine control unit 2003. In response to this, the TOP signal 207 and the LSYNC signal 20 are output from the engine control unit 2003.
8 is returned for a predetermined time.

Therefore, the printer control unit 2005 synchronizes the vertical scanning direction with the TOP signal 207, synchronizes the horizontal scanning direction with the LSYNC signal 208, and sets the VDO signal 21
1 in accordance with the VCLK signal 209, and
Transfer to 03. Here, since the color mode is set, the TOP signal 207 is generated four times, and toner images for four colors of C (cyan), M (magenta), Y (yellow), and K (black) are formed. Will be. Then, the printer control unit 2005 outputs the fourth TOP signal 2
07, the PRNT signal 206 is changed to High.
Return to (false). Thereby, the engine control unit 2003
Recognizes that the print processing related to the print request, that is, one print job has been completed,
The processing shifts to post-processing such as cleaning processing.

The transferred recording paper is applied to a fixing roller 4.
07, the paper is discharged from the specified paper discharge port.
Then, the printer control unit 2005 controls the engine control unit 2
A print status check signal is transmitted to 003 to confirm that the recording paper is not being conveyed, that is, that the discharge has been completed, and waits in a ready state until the next print request occurs.

If an illegal state such as a recording paper jam, no recording paper, or a door open by the user occurs during the above operation, the engine control unit 2003 sets the CCRT.
The device abnormality is immediately transmitted to the printer control unit 2005 using the signal 217, and the printer control unit 2005 performs a predetermined response process according to the abnormal state of the device.

[Configuration when Reader Control Unit is Attached] FIG. 10 shows the printing apparatus described above not only printing data transferred from the host computer but also optically reading an image on a document and printing it. FIG. 1 is a schematic diagram showing an overall mechanical configuration of a digital copying machine to which a copying function is added.

In FIG. 10, reference numeral 801 denotes a document
The document is fed by the document feeding device 801. The document is fed by the document feeding device 801.
This operation is performed in synchronization with the document reading operation of the document 101. That is, the original is moved by the original feeder 801 to the original table 102.
When transported upward, the reader unit 101 scans the original image while moving the light source 103 and the like in the left-right direction of FIG.
The reflected light subjected to the predetermined optical processing is converted into the photoelectric conversion element 104.
Incident on. The analog image data photoelectrically converted and output by the photoelectric conversion element 104 is converted into digital image data by the A / D converter 105,
The data is transferred to the photoconductor scanner 401. Then, the image forming process described with reference to FIG. 6 is performed.

When one print job, that is, the printing process for the same image is completed, the intermediate transfer member 4
05 while rotating the intermediate transfer body 40 during the rotation.
By bringing the cleaning blade 419 into contact with the intermediate transfer member 5, post-processing such as removal of toner attached to the intermediate transfer body 405 is performed. This post-processing will be described later in detail.

FIG. 11 is a schematic diagram showing the overall configuration of a control system when a reader control unit 2004 is added. FIG.
2, the reader control unit 2004 is arranged between the printer control unit 2005 and the engine control unit 2003 in FIG. The types of signals transmitted and received between the printer control unit 2005 and the reader control unit 2004 and between the engine control unit 2003 and the reader control unit 2004 are as follows.
The signal types are almost the same as those shown in FIGS. However, between the printer control unit 2005 and the reader control unit 2004, the engine control unit 2003 and the reader control unit 2004
Since the signals having the same function are physically different between, the signal names are distinguished by attaching C to the former and P to the latter.

An image input unit 901 inputs original image data output from the reader unit 101 to an image signal processing unit 902 in the reader control unit 2004. The image signal processing unit 902 is read by the reader unit. The converted image data is converted into raster format data so that it can be printed. 903
Reference numeral 904 denotes a document scanning optical system control unit that controls the reader unit 101, and reference numeral 904 denotes a document feeding control unit that controls the document feeding device 801. An operation unit 905 is used to set a post-processing delay mode, a monochrome / color print mode, the number of copies to be described, and the like.

The engine control unit 2003, the reader control unit 2004, and the printer control unit 2005
ROMs 2213, 2210, 2215 storing a control program for executing the above-described processing, and CPUs 2212, 2209, 2 for executing the control program
215 and RAM used as a work area, etc.
2214, 2211 and 2217.

FIG. 12 is a block diagram showing a detailed configuration of the reader control unit 2004. In FIG. 12, 220
Reference numeral 1 denotes a selector, which is image data from the image signal processing unit 902 (that is, the reader unit 101) or the printer control unit 2005 (that is, the host computer 210).
One of the image signals from 3) is selected and output to the engine control unit 2003. The signal system switched by the selector 2201 is a video clock signal (VCLK signal 2
09), an image enable signal (VDOEN signal 21)
0) and image data (VDO signal 211).

The image signal processing circuit 902 includes a circuit for performing a shading correction process described later. This shading correction processing will be described later in detail with reference to FIGS.

Reference numeral 2202 denotes a serial communication control unit for communicating with the engine control unit 2003. Reference numeral 2203 denotes an input / output port for transmitting and receiving signals for supplementing communication in the serial communication control unit 2202. Reference numeral 2204 denotes an interrupt control unit. The interrupt control unit 2204 receives an image leading end request signal (PTOP signal 207) and a printer state change signal (PCCRT signal 217). 2205
Is a serial communication control unit that communicates with the printer control unit 2005. Reference numeral 2206 denotes an input / output port for transmitting and receiving signals for supplementing communication in the serial communication control unit 2205.

Reference numerals 2207 and 2208 denote gates, which control whether a signal sent from the engine control unit 2003 is sent to the printer control unit 2005 or not. Gate 22
07, the line synchronization signal (PLSYNC signal 20
8) At the gate 2207, the image leading end request signal (PTO)
The P signal 207) is gated. A control circuit 2218 having a gate function and a flag setting function controls a printer state change signal (PCCRT signal 217). That is, the control circuit 2209 controls the engine control unit 2
Whether the printer status change signal (PCCRT signal 217) issued by 003 is transmitted to the printer control unit 2005 is controlled by opening and closing the gate, and a flag is set to change the printer status change signal (PCCRT signal 217). From the reader control unit 2004 to the printer control unit 2
005. 2209 is a reader control unit 2
The CPU controls the entire operation of the CPU 004. The ROM 2210 stores a control program corresponding to flowcharts shown in FIGS. 17 to 20 described later, a control program for performing shading correction processing, and a RAM 2211 used as a work area. Contains.

[Operation at Copying] Next, the operation at the time of reading and copying a full-color original image will be described. When a copy start key 2703 (not shown) on the operation unit 905 is pressed, the reader control unit 2004 is in the copy mode, so that the gates 2207 and 2208 and the control circuit 2218 are used.
Is closed, and the selector 2201 is set so that the output of the image signal processing unit 902 is selected. next,
Using the input / output port 2203, the engine control unit 200
For 3, the ready state signal (PRDY signal 203) of the printer engine 2002 is checked.

Various settings are made using the serial communication control unit 2202. That is, a command for designating the paper feed stage (cassette 408 or 409) of the recording paper is issued. Further, a command for requesting the size of the recording paper stored in the designated cassette is issued. In response to these commands, the engine control unit 2003 returns a corresponding status. Next, a command for specifying a paper discharge port is issued to determine the paper discharge port, and a copy (page mode) specification command for specifying how many copies of one document image are to be copied is issued. Finally, by issuing a command specifying one of monochrome and color, all the settings for the engine control unit 2003 are completed.

After a document is fed onto the document table 102 by the document feeder 801, the reader control unit 2004 sends a print request signal (P
PRNT signal 206). In response to this, the PTOP signal 20 is sent from the engine control unit 2003 after a predetermined time.
7 is returned, the reader control unit 2004 sets the PT
The OP signal 207 is processed by the interrupt control unit 2204, and the PTO
The reader unit 101 is operated so as to synchronize with the P signal 207. That is, the vertical scanning direction is synchronized with the PTOP signal 207, and the horizontal scanning direction is synchronized with the PLSYNC signal 208. Then, the PVDO signal 211 is changed to the PVCL
The image data processed by the image signal processing unit 902 is input from the photoelectric conversion element 104 to the engine control unit 20 in synchronization with the K signal 2098.
Transfer to 03.

Here, since the color mode is set, the PTO which operates the optical scanning system four times and generates four times
C (cyan), M (magenta),
An image for four colors of Y (yellow) and K (black) is formed. After generating the final PTOP signal corresponding to the designated number of copies, the PPRNT signal 206
Is returned to High (false). Accordingly, the engine control unit 2003 recognizes that the printing according to the print request has been completed, and shifts to post-processing such as a cleaning operation of the intermediate transfer body 405. Then, the transferred recording paper passes through the fixing roller 407, and is discharged to a specified discharge port. Finally, the reader control unit 2004 confirms with the engine control unit 2003 that the recording paper is not being transported (paper ejection has been completed), and continues until the next print request is issued.
Wait in ready state.

[Printing Operation] Next, the printer control unit 2005 (ie, the host computer 2103)
The operation in the case where the image is printed out will be described. When the copy operation is completed, the reader control unit 2004
Is ready. At this time, the reader control unit 2004 operates the gate units 2207 and 220 for the operation during printing.
8 and the control circuit 2218 are opened. Reader control unit 200
4 is an engine control unit 2 using the input / output port 2203.
Check the ready state signal (PRDY signal) of the printer engine 2002 with respect to 003, and if it is OK, use the input / output port 2206 and use the printer control unit 200.
5, the ready state signal (CRDY signal) of the printer engine 2002 is set.

Next, the printer control unit 2005 communicates with the reader control unit 2004 in order to make various settings. The reader control unit 2004 receives the setting signal by the serial communication control unit 2205 and interprets it by the CPU 2209. . Then, according to the interpretation, the reader control unit 200
4 performs various settings for the engine control unit 2003 via the serial communication control unit 2202.

The engine control unit 2003 sends a status signal corresponding to a series of commands to the reader control unit 2.
Reply to 004. When receiving the status signal from the engine control unit 2003 via the serial communication control unit 2202, the reader control unit 2004
209, and transmits it to the printer control unit 2005 using the serial communication control unit 2205.

Then, the printer control unit 2005 sends a print request signal (CPRN) to the reader control unit 2004.
T signal), the reader control unit 2004 generates a print request signal (PPRNT signal) to the engine control unit 2003 in response to the request. A PTOP signal is returned from the engine control unit 2003 to the reader control unit 2004 after a predetermined time in response to this request. The reader control unit 2004 transmits the PTOP signal to the gate 2208.
And transfers it to the printer control unit 2005 as a CTOP signal.

The printer control unit 2005 synchronizes the CVDO signal with CVCLK by synchronizing the vertical scanning direction with the CTOP signal and further synchronizing the horizontal direction with the CLSYNC signal transferred via the gate 2207.
Output to the reader control unit 2004. Leader control unit 200
4 is set so that the selector 2201 selects a signal from the printer control unit 2005. The signal sent from the printer control unit 2005 includes a PVCLK signal,
The signal is sent from the reader control unit 2004 to the engine control unit 2003 as a PVDOEN signal and a PVDO signal.

[Difference between Print Operation and Copy Operation] Next, the difference between the print operation and the copy operation will be described with respect to the image transmission timing. Although a detailed description of the configuration of the printer control unit 2105 is omitted, an image memory is provided therein, and image data to be printed is stored in the image memory in advance. Therefore, in response to the image leading end request signal (TOP signal) sent from the engine control unit 2003, the printer control unit 21
The time required for the print data 05 to output the print data (VDO signal) is only the electrical delay time.

On the other hand, in the copy mode,
The original is read while moving the optical scanning system of the reader unit 101, and image data is output. It takes a certain amount of time before print data (VDO signal) can be output. That is, as shown in FIG.
In order to accelerate the optical scanning system such as from the stop state to the speed at which the document is read, it takes a time of, for example, about several hundred milliseconds. Therefore, when the engine control unit 2003 sends the image leading end request signal (TOP signal) in the copy mode at the same timing as the signal in the print mode, the print image data (VD
The time when the O signal arrives in the copy mode is delayed by several hundred milliseconds in the copy mode.

As a countermeasure for this, a method of sending the TOP signal earlier in the copy mode than in the print mode, and a method of providing another signal (RSTART signal) for the copy mode can be considered. In order to execute the former method, the configuration in the reader control unit 2004 may be the same as in FIG. 12, and the engine control unit 2003
The P signal is transmitted several hundred milliseconds earlier in the copy mode than in the print mode. On the other hand, in order to execute the latter method, the reader control unit 2004 may have the configuration shown in FIG. That is, the engine control unit 2003
The image leading end request signal (PTOP signal) transmitted from
It functions as a signal required only when the printer control unit 2005 performs printing, and does not need to be input to the interrupt control unit 2205 of the reader control unit 2004 in the print mode. Also, the reading device movement start request signal (RSTART signal) sent from the engine control unit 2003 is:
This signal is required only in the copy mode, and need not be sent to the print control unit 2005.

[Control for Setting Command] Next, the characteristic control of the present invention will be described. Printer control unit 2
005 and the engine control unit 2003 between the reader control unit 2
With the connection of 004, communication between the printer control unit 2005 and the engine control unit 2003 is as follows.

The reader control unit 2004 is connected to the engine control unit 2
In the case where a document image is read and output using 003 (in the copy mode), for example, a paper feed cassette change command is issued as a setting command for the printer engine 2002 from the printer control unit 2005. I do.

FIGS. 15 and 16 show the reader control unit 2004.
15 shows the flow of the command issuing process in the configuration of FIGS. 2 and 3, FIG. 15 shows the process of the printer control unit 2005, and FIG.
3 shows the process of FIG.

After issuing the paper cassette change command (step S1), the printer control unit 2005 waits for a response from the engine control unit 2003 (step S2), and determines the success of the command execution when the response is received (step S2). Step S3). If the command execution is not successful, a predetermined error process is performed (step S4),
If the command has been completed and the command has been successfully executed, the process ends. Such a series of command issuing processing is similarly performed for various commands.

The engine control unit 2003 determines the contents of the command received from the printer control unit 2005 (step S5). As a result, in the case of the paper feed cassette change command, the paper feed cassette change setting is performed (step S6). Then, the printer control unit 2005 is notified of the cassette change success (step S7), and the process returns to step S5 to perform the same processing for the command from the printer control unit 2005.

When the reader control unit 2004 intervenes as shown in FIG. 11, the reader control unit 2004 communicates between the printer control unit 2005 and the engine control unit 2003 as shown in FIG.
Is performed. Also in this case, the printer control unit 2005 and the engine control unit 2003 perform the operations shown in FIGS.
Communication processing similar to the communication processing shown in FIG.

In FIG. 17, a reader control unit 2004
Transmits a command from the printer control unit 2005 to the CCMD.
The command is received as a signal via the serial communication control unit 2205 (step S11), and it is determined whether the command can be issued to the engine control unit 2003 as it is (step S12). For example, currently, the reader control unit 2
If no command is issued to the engine control unit 2003 to perform the copy mode operation, the engine control unit 2003 determines that the command can be issued. Control unit 2005
The same command as the command sent from the PCM is sent to the engine control unit 2003 by the serial communication control unit 2202 and the PCM.
Issued via the D signal line (step S13). Next, it waits for a response from the engine control unit 2003 (step S14), and determines the success of the command execution when the response comes (step S15). If the command execution is not successful, a predetermined error process is performed (step S17), and the process returns to step S11. If the command execution is successful, a message that the command execution was successful is returned to the printer control unit 2005 (step S1).
6), and return to step S11.

On the other hand, for example, when the reader control unit 2004 performs a copying operation by designating a paper feed cassette, the paper feed cassette change command sent from the printer control unit 2005 is sent to the engine control unit 2003 without change. In the case where the copying operation is not normally executed if issued, in step S12, it is determined that the command cannot be issued, and the command is not issued to the engine control unit 2003 without being issued. Is stored in the engine command queue (step S18). Note that commands are accumulated in the engine command queue in the order of issuance from the printer control unit 2005. Since it is necessary to return a response to the command to the printer control unit 2005, it is determined that the command has been successfully executed, and a signal to that effect is sent from the reader control unit 2004 to the serial communication control unit 2.
205, printer control unit 2 via CSTS signal line
005 is returned (step S16).

Next, referring to FIG.
04 without affecting the state of the printer control unit 200
A case will be described in which it becomes possible to issue a command from engine control unit 2003 to engine control unit 2003.

The reader control unit 2004 waits until a command from the printer control unit 2005 can be issued to the engine control unit 2003 (step S21). Then, when it becomes possible to issue a command, the reader control unit 2004 issues a command stored in the engine command queue to the engine control unit 2003 (step S22). At this time, the serial communication control unit 22
Use 02 to issue a command through the PCMD signal line. Note that a command issued by the reader control unit 2004 itself is also transmitted to the engine control unit 2003 through the PCMD signal line.

When the command execution is completed, a response is returned from the engine control unit 2003 to the reader control unit 2004 via the PSTS signal line.
004 waits for a response from the engine control unit 2003 (step S23), and when the response is received, determines success of the command execution (step S24). If the command execution is successful, the command related to the successful execution is deleted from the engine command queue (step S25), and the process returns to step S21. At this point, the printer engine 200
If it is determined that the execution of the command by F.2 has failed, it is processed as an error occurrence state (step S2).
6) Return to step S21.

As described above, even in the case of the configuration in which the reader control unit 2004 is interposed, inconsistency does not occur in the operation when a normal command is issued from the printer control unit 2004 to the engine control unit 2003.

[Control for State Change Signal] Next, in a configuration in which the reader control unit 2004 is interposed, the fact that the state of the printer engine 2002 has changed (for example, an error has occurred) is determined by using the PCCRT signal. A process performed when the information is transmitted from the engine control unit 2003 to the reader control unit 2004 will be described.

In the case of the configuration in which the reader control unit 2004 is interposed, there is a possibility that the reader control unit 2004 and the printer control unit 2005 may change the desired state differently. For example, this is the case where a state change occurs such that the recording paper being conveyed is jammed. If a jam occurs while the printer engine 2002 is performing a copying operation under the control of the reader control unit 2004, this state is determined by the reader control unit 2004.
Only want to know. Since the printer control unit 2005 is not a jam while outputting image data, the printer control unit 2005 cannot execute appropriate post-processing even if notified of this state.

When a control system equivalent to the reader control unit 2004 is to be mounted on the printer control unit 2005, software for jam processing control which the other should have is mounted on both control units. It is disadvantageous in terms of design man-hours, quality evaluation, software capacity, and the like.

Therefore, a control system equivalent to the reader control unit 2004 is not mounted on the printer control unit 2005.
To the reader control unit 20 in the copy mode.
04. However, even in the copy mode, the printer control unit 2005 may want to know the state change of the printer engine 2002. For example, it is necessary to notify the printer control unit 2005 of information such as a change in cassette size and no paper. However, with respect to the change of the recording paper cassette, that is, the information such as the change of the recording paper size and the absence of the recording paper, the time from when the information is issued by the engine control unit 2003 to when the processing is performed by each control unit is strict. Don't ask.

Therefore, the following processing is performed. That is, in the copy mode in which the reader control unit 2004 controls the engine control unit 2003,
The state change signal (PCCRT signal) notified from the engine control unit 2003 is masked for the printer control unit 2005 using the gate function of the control circuit 2208, and only the reader control unit 2004 controls the interrupt control unit 220.
4 to receive.

Then, the reader control unit 2004
The processing is performed according to the control flow of (1). That is, PCCRT
When the signal becomes true (step S31), the reader control unit 2004 issues a command for acquiring a state change to the engine control unit 2003 (step S32).
Thereafter, the status transmitted from the engine control unit 2003 is checked (step S33), and the contents of the status change of the printer engine 2002 are grasped (step S3).
4).

Then, it is determined whether or not the content of the status change is a content to be notified to the printer control unit 2005 (step S35). For example, it is determined that a state change such as a change in the recording paper cassette is a state change to be notified to the printer control unit 2005. If it is determined that the notification should be made, a flag is set using the control circuit 2208, and a state change signal (CCCRT signal) is generated to notify the printer control unit 2005 (step S36).

Next, the process waits for a status change inquiry from the printer control unit 2005 (step S37). As soon as the inquiry is received, the status change signal (status) received from the engine control unit 2003 is transmitted to the printer control unit 2005 (step S37). (Step S38), the CCCRT signal is set to false (Step S39), and the process ends. On the other hand, step S35
When it is determined that the status change is not a status change to be notified to the printer control unit 2005, only the reader control unit 2004 executes processing for the status change (step S4).
0), end.

In the print mode in which the printer control unit 2005 controls the engine control unit 2003, the reader control unit 2004 opens the gate in the control circuit 2208 and is notified from the engine control unit 2003. All the state change signals (PCCRT signals) are converted into state change signals (CCCRT signals) by the printer controller 20.
05 is notified.

[Control for Execution Command] Next, control of the execution command will be described. For example, how the reader control unit 2004 controls when the printer control unit 2005 and the reader control unit 2004 simultaneously issue use requests to the engine control unit 2003 will be described.

FIG. 20 is a diagram showing the location of data when a print request is issued during a copy operation, and the transfer of the data.

At the time of the copy operation, the engine control unit 200
3 is an image signal (PVDO) from the reader control unit 2004
Signal). In this case, the settings such as the sheet cassette designation, the sheet ejection port designation, and the image forming mode described with reference to FIG. 9 have already been made by serial communication between the reader control unit 2004 and the engine control unit 2003.

Reference numeral 1301 in FIG. 20 denotes a buffer for various settings. The buffer 1301 stores the values set by the reader control unit 2004 for the engine control unit 2003 and the printer control unit 200.
5, the values set for the engine control unit 2003 are respectively for the reader and PDL (Page
It is stored in a buffer for an option language (ie, a printer control unit).

Here, during the copying operation, the printer control unit 2
Since it is not advisable from the viewpoint of usability to interrupt the copy operation and perform the printout when a print request is issued from 005, the print request in this case is postponed until the copy operation is completed. Become. However, the CSTS signal must be returned from the printer control unit 2005 in response to the CCMD signal. Therefore, the setting value from the printer control unit 2005 is also temporarily set in the PDL buffer in response to a request. If the set value for the reader is different from the set value for the PDL, the setting is performed from the reader control unit 2004 to the engine control unit 2003 before the copy operation ends and the printer operation starts.

The following is a description of a specific example. That is, it is assumed that a copy operation is currently being performed, paper is to be fed from the upper recording paper cassette, and the paper is to be discharged to the face-up discharge port, and the color mode is also set in the image forming mode. In this state, the printer control unit 2005
When a print request is issued from, print execution itself is postponed, but various settings are made. For example, it is assumed that the print request is a request to feed paper from the upper recording paper cassette, discharge the paper to the face-down discharge port, and further output a monochrome image. In this case, regarding the designation of the recording paper cassette, the reader control unit 2004, the printer control unit 200
5 specifies the upper cassette. Therefore, even when the copy operation is completed and the operation is switched to the print operation, there is no need to issue a paper feed cassette designation command to the engine control unit 2003. Regarding the discharge port and the image forming mode, since the designation is different between the copy operation and the print operation, when the copy operation ends, the reader control unit 2004
Issue a command to specify the paper discharge port and the image forming mode to the engine control unit 2003 again.

As described above, the reader control unit 2004
In response to the command from the printer control unit 2005, processing for only delaying the execution of the command to the engine control unit 2003 is not performed.
Does not duplicate a command already set in the engine control unit 2003.

Next, a case where a copy request occurs during a printing operation will be described with reference to FIG. In this case, contrary to the case of FIG. 21, from the viewpoint of usability, it is better to be able to execute the copy operation in an interrupted manner than to be able to copy during the print operation even if the copy start key is pressed.

As shown in FIG. 21, during the printing operation, the CVDO signal transmitted from the printer control unit 2005 is selected by the selector 2201 and sent to the engine control unit 2003 as PVDO. It is assumed that the settings from the printer control unit 2005 are the upper cassette, the face-down discharge port, and the black-and-white image mode just like the case described with reference to FIG.

Since the engine control unit 2003 can detect the end only when the PPRNT signal from the printer control unit 2005 becomes High (false), it cannot recognize how many sheets are printed out. Here, assuming that four images are to be printed out, unless the reader control unit 2004 interrupts and makes a copy operation request, four PTOP signals are generated from the engine control unit 2003, and the image Data is stored in the printer control unit 20
From 2005, the data is sent to the engine control unit 2003 via the reader control unit 2004.

It is assumed that an interrupt copy request to copy one color original is issued to the reader control unit 2004 during the second printout. This example will be described with reference to FIG. C from the printer control unit 2005
In response to the PRNT request, the reader control unit 2004
A T request is issued to the engine control unit 2003. Then, a PTOP signal is supplied from the engine control unit 2003 to the printer control unit 2005 as a CTOP signal via the reader control unit 2004. Thus, 150
The printing operation of the first image shown in FIG. 1 and the second image shown in 1502 is executed.

When detecting an interrupt copy request during the printout operation of the second pattern, the reader control unit 2004 sends a CCCRT signal to the printer control unit 2005. This does not mean that the state of the printer engine 2002 has actually changed, but requests the printer control unit 2005 to release the printer engine 2002 in order for the reader control unit 2004 to acquire the right to use the printer engine 2002.

When transmitting the CCCRT signal, the control unit 2218 is used as described above. In response to the CCCRT signal, the printer control unit 2005 issues a command for checking the status of the printer engine 2002, and the reader control unit 2004 notifies the printer control unit 200 of the status indicating that a copy operation is being performed.
Reply to 5. Then, the printer control unit 2005 detects that the printer engine 2002 is performing a copy operation, and continues to wait for a CTOP signal to be received while the CPRNT signal remains Low (true).

If the CPRNT signal is kept low (true) and a CTOP does not arrive unless the copy state is established, a timeout error occurs after a certain period of time. Release and set to wait for the CTOP signal forever. In the present case, the PTOP signal sent from the engine control unit 2003 is for performing a copy operation, and the reader control unit 2004 uses the PTOP signal. Also, as indicated by 1505, the engine control unit 20
03 from the printer control unit 2
005 is to be masked. The image signal actually generated by the reader control unit 2004 is only the image signal 1506.

After one interrupt copy is completed,
By unmasking the PTOP signal again and sending it to the printer control unit 2005 as the CTOP signal, the image signals 1503 and 150 from the printer control unit 2005 are output.
4 can be transferred to the engine control unit 2003 and printed out.

As described above, according to the states of the printer control unit 2005 and the reader control unit 2004, the reader control unit 2004 determines which one obtains the right to use the printer engine 2002 and at what timing the command is issued.
Makes it possible to execute the printing process according to the requests from the two control units even with only one printer engine 2002.

[Control for Setting Content Confirmation Command] Next, control when the printer control unit 2005 issues a setting content confirmation command will be described.

When the printer control unit 2005 wants to confirm the state set in the engine control unit 2003, the printer control unit 2005 transmits a setting content confirmation command to the CCM.
Issued as D signal. Reader control unit 2 that received it
004 checks the setting value storage buffer 1301 in FIG. 20, and if the content to be confirmed by the printer control unit 2005 exists in the buffer 1301, the content is read out and sent to the printer control unit 2005 via the CSTS signal line. Notice.

If the setting is not stored in the setting value storage buffer 1301, the reader control unit 2004 transfers the setting content confirmation command to the engine control unit 2003 via the PCMD signal line. The engine control unit 2003
The content is read, and the corresponding setting content is notified to the reader control unit 2004 via the PSTS signal line, and the reader control unit 2004 notifies the content to the printer control unit 2005 via the CSTS signal line.

Next, a case where a monochrome image is output in the single-sheet pasting mode will be described. When the copy start key is pressed after the monochrome mode key on the operation unit 905 is pressed, the reader control unit 2004
The various settings described above are performed, and a document is fed onto the document table 102 by the document feeding device 801. At that time, the document feeder 801 detects the size of the document and
04 is notified. If the notified document size is such that two sheets cannot be pasted on the intermediate transfer break 405 or if the recording paper is large, the reader control unit 2004 determines that the operation is in the single-sheet pasting mode. First, the paper feed stage of the recording paper cassette is determined according to the document size, and a designation command is issued. Further, a command for requesting the size of the recording paper stored in the designated recording paper cassette is issued. The engine control unit 200 responds to these series of commands.
3 returns the corresponding status.

Next, a discharge port is determined by a command for specifying a discharge port, and a page mode designation command for designating one-page image formation is issued based on the above determination. Finally, by issuing a command for specifying monochrome, all settings for the printer engine 2002 are completed.

Next, the reader control unit 2004 sends a print request signal (PPRN) to the engine control unit 2003.
T signal). In response to this, a PTOP signal is returned from the engine control unit 2003 after a predetermined time. This is processed by the interrupt control unit 2204, and the PTOP
The document scanning optical system control unit 903 is operated so as to synchronize with the signal. The vertical scanning direction is synchronized with the PTOP signal, the horizontal direction is synchronized with the PLSYNC signal, and the PVD
The image signal input from the document scanning optical system control unit 903 (photoelectric conversion element 104) to the image signal processing unit 902 is synchronized with the O signal in synchronization with PVCLK.
Transfer to 3.

In this case, since the monochrome mode is set, the document scanning optical system control unit 903 is operated once, and an image for one black color is formed for the PTOP signal generated once. When the one page image forming mode is set,
The PTOP signal is generated once while the intermediate transfer body 405 makes one rotation. As soon as the optical reading for one color is completed, the original is replaced by the original feeder 801.

[Shading Correction Processing] Next, the shading correction processing unique to the present invention will be described.

FIG. 23 is a functional block diagram relating to the shading correction processing. 23, a CCD (imaging device) 104 and an A / D converter 105 correspond to those shown in FIG. 1 and the like, and a CPU 2209 and a RAM 2211 correspond to those shown in FIG.
2 and the like, and this RAM 2211 has
A line memory 3002 for storing white reference data a (n) described later is formed. Also, the CPU 220
9 includes a comparison circuit 3010, a reference value register 3011,
Monochrome (black and white) original / color original / register 301
2 and a gain range control unit 3013 are provided.

A reference value T for comparison with the above-mentioned white reference data is set in the reference value register 3011. The comparison circuit 3010 calculates the reference value T and the white reference data a.
(N). In the monochrome original / color original register 3012, information of the monochrome original / color original determined by actually scanning the original is set instead of the monochrome / color mode information set by the operation unit 905.

The gain range control unit 3013
Under the control of the CPU 2209, the selector 300 based on the information set in the monochrome original / color original register 3012 and the comparison result by the comparison circuit 3010.
3,3006, the gain ranges GR1 and GR2 described later are switched.

Note that the analog signal processing circuit 3001
It is omitted in FIG. 1 and the like. In the present embodiment, C
As the CD (image pickup device) 104, a linear (line) type for one dimension is used, but an image (area) type for two dimensions can also be used. The CCD (image pickup device) 104 is a color CC capable of reading a color image.
When the full-color mode is set, the optical scanning of the document P is performed four times.

The selectors 3003 and 3006 and the divider 3
004, 3005, the multiplier 3008, and the multiplication coefficient register 3007 correspond to the reader control unit 220 shown in FIG.
4 is built in the image signal processing unit 902.

As shown in FIG. 24A, the light source 103
Platen 102 facing the vicinity of home position HP
A reference white plate W is provided at the upper position. The reference white plate W is used to control the characteristics of the CCD 104 in the image data read by the CCD 104, the light distribution of the incident light, the lens 3
It is provided to obtain reference data for correcting density unevenness caused by aberration of 009, contamination of the document table (glass table) 102, and the like.

That is, before actually reading the original, the light source 103 and the mirror group 106 are moved to irradiate the reference white plate W with light from the light source 103, and the reflected light is reflected by the mirror group 10
6. The light is incident on the CCD 104 via the lens 3009 and is subjected to photoelectric conversion [see FIG. 24 (a)]. Then, the analog signal processing circuit 3001 extracts a signal component corresponding to the reference white plate W from the analog signal output from the CCD 104, and the A / D converter 105 converts the signal component into digital data.

As shown in FIG. 24 (a), the reference white plate W is provided on the side opposite to the original scanning direction with respect to the home position HP.
Is read, the light source 103 and the mirror group 106 are moved in a direction opposite to the document scanning direction, and this is called a back scan.

The digital data corresponding to the reference white plate W [see the circle in FIG.
2 is stored. The digital data corresponding to the reference white plate W stored in the line memory 3002 is
Is the image data that reflects the characteristics of the lens 3009, the aberration of the lens 3009, etc., and white reference data a (n) for shading correction.
[See a1 to a (n) in FIG. 25 (b)]. Note that, as the white reference data a (n), the average value of the white reference data for a plurality of lines of each pixel is actually stored in the line memory 3002.

The selectors 3003 and 3006 are selectors for switching the gain ratio, and the CPU 2209
Is switched to one of the gain ranges GR1 and GR2. The dividers 3004 and 3005 output the original image data d (n) obtained by optically scanning the original P [FIG.
(B) d1 to d (n)] are converted to white reference data a
Divide by (n). A predetermined multiplication coefficient (shading target value Tsh) is stored in the multiplication coefficient register 3007, and the shading target value Tsh is calculated by the multiplier 3008 as d (n) / which is the result of division by the dividers 3004 and 3005. a (n) is multiplied. And
As shown in FIG. 26B, the multiplication result d
(N) × Tsh / a (n) is output as a shading correction result. In this case, as shown in FIG. 25B, the shading correction coefficient is Tsh / a (n) [n
= 1, 2,... N].

Here, the meaning of the “gain range” will be described. In other words, when the light source 103 deteriorates, the light distribution deteriorates and the white reference data a (n) decreases. To compensate for this, the width of the magnification when the white reference data a (n) is scaled is increased by a gain. We call it range.

In the present embodiment, the width of the magnification is x1.
Gain range GR1 of ~ × 2 (1 to 2 times) and × 1
A gain range GR2 of ×× 4 (1 × to 4 ×) is used. When the gain range GR1 is used, the white reference data is set in the range of a (n) to 2a (n). Therefore, the range in which shading correction is possible is 50% to 100% of the shading target value Tsh. %. When the gain range GR2 is used, the white reference data is set in the range of a (n) to 4a (n). Therefore, the range in which shading correction is possible is 25% of the shading target value Tsh. ~ 100%. In other words, in the case of the gain range GR1, the gain range GR2
, The shading correction coefficient Tsh / a
The range that can be taken by (n) is doubled, so that the shading correction can be performed more finely and printing can be performed with twice the resolution with high accuracy.

The same number of gradations (for example, 50 gradations) in the case of the gain range GR1 and the case of the gain range GR2
When the image data is expressed by white reference data a (n)
The width (step width) per gradation is as follows.

That is, the range of [1 / a (n)] in the case of the gain range GR1 is 0.50 ≦ 1 / a (n) ≦
1.00 and its width 1.00-0.50 = 0.50
Is divided by 50, the step width per gradation becomes 0.010. The range of [1 / a (n)] in the case of the gain range GR2 is 0.25 ≦ 1 / a
(N) ≦ 1.00, and its width 1.00−0.25 =
When 0.75 is divided by the number of gradations of 50, the step width per gradation becomes 0.015.

Therefore, even if the number of gradations is the same,
In the case of the gain range GR1, it is possible to perform printing with a resolution 1.5 times as high as that of the gain range GR2 with high accuracy. In other words, it is possible to represent a plurality of gain ranges with the same memory capacity.

[Example of Gain Range Switching Control] Next, an example of switching control of the gain ranges GR1 and GR2 will be described with reference to the flowchart of FIG.

That is, the gain control unit 3013 normally sets the gain range GR1 (step S5).
1). Then, the white reference plate W is optically scanned by the back scan, and the original is optically scanned by the forward scan (step S52).
(N) and document image data are obtained (step S53). At this time, the white reference data a1 to a (n) are stored in the line memory 3
002, and the original image data is stored in the RAM 2211.

Next, it is determined whether or not the original to be read is a color original based on the original image data (step S54). As a result, if the original is a color original, information indicating that the original is a color original is set in the monochrome original / color original register 3012, and the white reference data a1 to a (n) are read from the line memory 3002 (step S5).
5). Then, several white reference data having a large value among the white reference data a1 to a (n) are selected, an average value thereof is obtained, and it is determined whether or not the average value is equal to or more than the reference value T (step). S56).

As a result, if the average value is equal to or larger than the reference value T, the gain range is switched to the gain range GR2 (step S5).
7) Enter the main scan. That is, the original is optically scanned by the forward scan (step S58), and the original image data obtained by the optical scanning is stored in the RAM 2211 (step S59), and the process returns to step S51. Is performed. If it is determined in step S56 that the average value is smaller than the reference value T, step S57 is skipped, that is, step S58 is performed while the gain range GR1 is set.
To enter the main scan.

As described above, without using the white reference data of the peak value, the average value and the reference value T of several large white reference data among the white reference data a1 to a (n) are obtained. The reason for comparing the gain ranges is to determine the switching of the gain range because large white reference data suddenly occurs due to the contamination of noise, and the gain range GR1 may actually be kept. This is to prevent switching to the range GR2.

If it is determined in step S54 that the document is a monochrome document, the flow advances to step S57 to set information indicating that the document is a monochrome document in the monochrome document / color document register 3012 and switch to the gain range GR2. (See FIG. 28). That is, for a monochrome original, the white reference data a1 is always stored in the gain range GR2.
Ａa (n) is scaled, and a shading correction coefficient is determined based on the scaled white reference data.

In this embodiment, the gain range GR
When 1 is selected, the light amount of the light source 103 is reduced, and when the gain range GR2 is selected, the light amount of the light source 103 is increased. In other words, in the case of a color original, switching to the gain range GR1 and increasing the light amount are performed only when the luminance decreases and the value of the white reference data decreases, otherwise, the gain range GR
In the case of a monochrome original, the gain range GR2 is always set and the light amount is reduced to extend the life of the light source 103.

Further, the monochrome original / color original is determined by scanning the original irrespective of the monochrome / color mode set by the operation unit 905, even if the original is a color original. GR
By setting the light amount to 1 or less, the light source 103
This is for the purpose of extending the life of the battery.

[Another example of gain range switching control]
FIG. 2 shows an example of switching control of other gain ranges GR1 and GR2.
The description will be made based on 9 to 31. In this example, as shown in FIG. 29, a character priority mode / image priority mode register 3014 for setting a character priority / image priority mode is provided instead of the monochrome original / color original register 3012. . The character priority mode / image priority mode information is set in the character priority mode / image priority mode register 3014 by a setting operation of the operation unit 905.

Next, gain switching control under such a configuration will be described with reference to the flowchart of FIG.

The gain control unit 3013 first determines which mode is set in the character priority mode / image priority mode register 3014 (step S6).
1). As a result, if the image mode is set,
The gain range GR1 is set (step S62). Then, the white reference plate W is optically scanned by the back scan and the original is optically scanned by the forward scan (step S63), and white reference data a1 to a (n) and original image data are obtained (step S64). At this time, the white reference data a1 to a (n) are stored in the line memory 3002, and the document image data is stored in the RAM 2211.

Next, the white reference data a1 to a (n) are read from the line memory 3002 (step S65).
Then, several white reference data having a large value among the white reference data a1 to a (n) are selected, an average value thereof is obtained, and it is determined whether or not the average value is equal to or more than the reference value T (step). S66).

As a result, if the average value is equal to or larger than the reference value T, the gain range is switched to the gain range GR2 (step S6).
7: See FIG. 31), and enters the main scan. That is, the original is optically scanned by the forward scan (step S6).
8) The original image data obtained by the optical scanning
M2211 (step S69) and step S69.
Returning to step 68, the main scan is performed for the next document. On the other hand, if the average value is smaller than the reference value T, step S67
Is skipped and the process proceeds to step S68, so that the main scan is started with the gain range GR1 remaining. If it is determined in step S61 that the character priority mode has been set, the process immediately proceeds to step S67, switches to the gain range GR2, and enters the main scan.

As described above, without using the white reference data of the peak value, the average value of several large white reference data among the white reference data a1 to (n) and the reference value T are calculated. The reason why the comparison of the gain range is determined by the comparison is that large white reference data is suddenly generated due to mixing of noise, and the gain range GR1 may be actually kept as it is. This is to prevent switching to GR2.

As described above, in the character priority mode, the white reference data a1 to a
(N) is scaled, and in the image priority mode, the gain range GR1 is switched to the gain range GR2 as needed to scale the white reference data a1 to a (n). And
A shading correction coefficient is determined based on the scaled white reference data.

In this embodiment, the gain range GR
When 1 is selected, the light amount of the light source 103 is reduced, and when the gain range GR2 is selected, the light amount of the light source 103 is increased. In other words, in the image priority mode, the mode is switched to the gain range GR1 and the light amount is increased only when the luminance decreases and the value of the white reference data decreases, and otherwise, the gain range GR
2, the light amount is reduced, and in the character priority mode, the gain range GR2 is always set and the light amount is reduced to extend the life of the light source 103.

In this embodiment, the selector 300
3,3006, divider 3004,3005, multiplier 30
Although the shading correction processing function such as 08 is realized by software, it is also possible to realize the shading correction processing function by pure hardware. Further, the light amount of the light source 103 can be always constant. Further, the gain range may be switched in more than two stages.

[0144]

As described above, according to the present invention,
It is possible to extend the life of the light source while maintaining good shading correction accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an overall configuration of a color copying apparatus to which an image forming apparatus according to an embodiment of the present invention is applied.

FIG. 2 is a basic system configuration diagram of a control system when a reader control unit is not interposed.

FIG. 3 is a schematic diagram illustrating an overall configuration of a printing apparatus to which the basic system of FIG. 2 is applied.

FIG. 4 is a diagram showing signals transmitted and received between the printer control unit and the engine control unit in FIGS. 2 and 3;

FIG. 5 is a diagram showing names of signals (abbreviations) in FIG. 4;

FIG. 6 is a schematic diagram showing an overall mechanical configuration of a printer engine.

FIG. 7 is a time chart for explaining the timing of video signal transfer.

FIG. 8 is a time chart showing signal transmission and reception during a printing operation.

FIG. 9 is a sequence diagram illustrating a flow of signals transmitted and received between a printer control unit and an engine control unit during a printing operation.

FIG. 10 is a schematic diagram showing an overall mechanical configuration of a digital copying machine.

FIG. 11 is a basic system configuration diagram of a control system when a reader control unit is added.

FIG. 12 is a block diagram illustrating a detailed configuration of a reader control unit.

FIG. 13 is a diagram for explaining a difference between image supply timings at the time of copying and at the time of printing.

FIG. 14 is a block diagram showing another detailed configuration of the reader control unit.

FIG. 15 is a flowchart illustrating processing of the printer control unit in response to a setting command when the reader control unit is not attached.

FIG. 16 is a flowchart illustrating a process of the engine control unit in response to a setting command when the reader control unit is not mounted.

FIG. 17 is a flowchart illustrating processing of the reader control unit in response to a setting command when the reader control unit is mounted.

FIG. 18 is a flowchart illustrating a process of the reader control unit when a setting command can be issued to the engine control unit;

FIG. 19 is a flowchart illustrating a process of acquiring the status of the humlinta engine when the reader control unit is mounted.

FIG. 20 is a diagram illustrating a command holding process for a print request during a copy operation.

FIG. 21 is a diagram illustrating a command holding process for a copy request during a printing operation.

FIG. 22 is a time chart showing a signal generation state at the time of interrupt copying.

FIG. 23 is a functional block diagram relating to shading correction processing.

FIG. 24 is a diagram for describing a process of obtaining reference data for shading correction.

FIG. 25 is a diagram showing a shading correction coefficient.

FIG. 26 is a diagram illustrating document read data and data after shading correction of the document read data.

FIG. 27 is a flowchart illustrating an example of gain range switching control.

28 is a diagram illustrating a determination condition of gain range switching in the gain range switching control example of FIG. 27;

FIG. 29 is a functional block diagram related to shading correction processing corresponding to another example of gain range switching control.

FIG. 30 is a flowchart illustrating another example of gain range switching control.

31 is a diagram illustrating a determination condition of gain range switching in the example of gain range switching control of FIG. 30. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 ... Reader part 103 ... Light source 104 ... CCD 405 ... Intermediate transfer body 801 ... Document feeding device 903 ... Document scanning optical system control part 904 ... Document feeding control part 905 ... Operation part 2003 ... Engine control part 2004 ... Reader control part 2005 printer controller 2209 CPU 2210 ROM 2211 RAM 3002 line memories 3003 and 3006 selector 3004 and 3005 divider 3007 multiplication coefficient (shading target value) register 3008 multiplier 3009 lens 3010 comparison circuit Reference numeral 3011: Reference value register 3012: Monochrome original / color original register 3013: Gain range control unit 3014: Character priority mode / image priority mode register P: Original W: Reference white plate

Continued on the front page F term (reference) 2C087 AA18 AB05 AC08 BA07 BB10 DA01 5B047 AA01 AB02 BB02 CB21 DA04 5C072 AA01 BA08 CA14 EA05 FB12 RA16 UA02 UA05 XA01 5C077 MM03 MM27 MP08 PP06 PP11 P46 PQ03Q18

Claims (16)

[Claims] An optical image obtained by optically scanning an original is photoelectrically converted. Original image data read by a reading unit that reads the original by photoelectrically converting the optical image is obtained by optically scanning a reference image by the reading unit. In the image forming apparatus having a shading correction function of performing shading correction using the obtained reference image data, the reference image data read by the reading unit is compared with a reference value according to the type of the document to be read. Determining means for determining whether to change the width of the scaling factor of the reference image data, and a gain for switching the width of the scaling factor when scaling the reference image data based on at least the determination result by the determining means. An image forming apparatus comprising: a range switching unit. 2. The image forming apparatus according to claim 1, wherein the gain range switching unit switches the width of the magnification ratio to a smaller one at an initial stage of the image forming operation. 3. The image forming apparatus according to claim 1, wherein the type of the document to be read is determined based on document image data read by the reading unit. 4. The apparatus according to claim 1, wherein the determining unit determines that the width of the magnification is switched to a wider one when the original to be read is determined to be a black and white original. An image forming apparatus according to any one of the above. 5. When the original to be read is determined to be a color original, the determination unit determines that the value of the reference image data obtained by optically scanning the reference image by the reading unit is large. The average value of several reference image data is compared with a reference value, and when the average value is equal to or more than the reference value, the width of the magnification is switched to a wider one. When the average value is smaller than the reference value, The image forming apparatus according to claim 1, wherein the image forming apparatus determines to keep the width of the magnification ratio narrow. 6. A light amount control unit that increases the light amount of the reading unit when the width of the magnification is switched to a narrower one by the gain range switching unit, and decreases the light amount when the width of the magnification is switched to a wider one. The image forming apparatus according to claim 1, further comprising: 7. An original image obtained by optically scanning an original image data read by a reading unit for reading an original by photoelectrically converting an optical image obtained by optically scanning the original. An image forming apparatus having a shading correction function for performing shading correction using the obtained reference image data, wherein the reference image data read by the reading unit is compared with a reference value according to a mode, and the reference image data is compared with the reference value. Determining means for determining whether or not to switch the width of the magnification, gain range switching means for switching the width of the magnification when scaling the reference image data based on at least the determination result by the determination means, An image forming apparatus comprising: 8. The image forming apparatus according to claim 7, wherein the mode is set by a setting operation by an operation unit. 9. The image according to claim 7, wherein, when the character priority mode is set, the determination unit determines to switch the magnification ratio to a wider one. Forming equipment. 10. The image forming apparatus according to claim 7, wherein when the image priority mode is set, the gain range switching unit switches the width of the magnification ratio to a smaller value at an initial stage of the image forming operation. The image forming apparatus according to any one of claims 1 to 9, 11. When the image priority mode is set, the judging means includes a plurality of reference image data having a large value among reference image data obtained by optically scanning the reference image by the reading section. The average value of the data is compared with a reference value, and when the average value is equal to or more than the reference value, the width of the magnification is switched to a wider one. When the average value is smaller than the reference value, the width of the magnification is changed. The image forming apparatus according to any one of claims 7 to 10, wherein the determination is made so that is kept narrow. 12. A light amount control unit that increases the light amount of the reading unit when the width of the magnification is switched to a narrower range by the gain range switching unit, and decreases the light amount when the width is switched to a wider range. The image forming apparatus according to claim 1, further comprising: 13. An optical image obtained by optically scanning an original is photoelectrically converted. Original image data read by a reading unit for reading the original is read by the optical scanning of a reference image by the reading unit. In an image forming method applied to an image forming apparatus having a shading correction function of performing shading correction using the obtained reference image data, the reference image data read by the reading unit according to the type of a document to be read And comparing the reference value and determine whether to switch the width of the magnification of the reference image data,
An image forming method, characterized in that a width of a scaling factor when scaling the reference image data is switched based on the determination result. 14. An image obtained by optically scanning an original image data read by a reading section for reading an original by photoelectrically converting an optical image obtained by optically scanning the original. In an image forming method applied to an image forming apparatus having a shading correction function of performing shading correction using the obtained reference image data, the reference image data read by the reading unit and a reference value are determined according to a mode. Determining whether to change the width of the magnification ratio of the reference image data by comparison, and switching the width of the magnification ratio when scaling the reference image data based on the determination result. Forming method. 15. An optical image obtained by optically scanning an original is photoelectrically converted. Original image data read by a reading unit that reads the original by optically scanning a reference image by the reading unit. A computer-readable medium applicable to an image forming apparatus having a shading correction function for performing shading correction using the obtained reference image data, wherein the reference read by the reading unit according to the type of the document to be read Determine whether to switch the width of the magnification of the reference image data by comparing the image data and the reference value,
A medium having a content for switching a width of a scaling factor when scaling the reference image data based on the determination result. 16. An optical image obtained by optically scanning an original is photoelectrically converted. Original image data read by a reading unit that reads the original is optically scanned by the reading unit to obtain a reference image. A computer-readable medium applicable to an image forming apparatus having a shading correction function for performing shading correction using the obtained reference image data, wherein the reference image data and the reference value read by the reading unit according to a mode. To determine whether to change the width of the scaling factor of the reference image data, and to switch the width of the scaling factor when scaling the reference image data based on the determination result. A medium characterized by the above.