Image formation apparatus Number:7,426,352 from the United States Patent and Trademark Office (PTO) owispatent An image formation apparatus includes an automatic adjustment unit for automatic adjustment of the apparatus, a job queuing unit for queuing image formation jobs, a counting unit for counting the number of pages from the previous automatic adjustment for each automatic adjustment unit, and a determining unit for determining whether the number of image formation pages for automatic adjustment will be reached during the execution of the image formation queued job. In the event that the determining unit determines that the number of image formation pages for automatic adjustment will be reached during execution of the image formation job queued by the job queuing unit, automatic adjustment is performed before starting execution of the image formation queued job, even though the number of image formation pages counted by the counting unit has not reached the number for the automatic adjustment.<H apparatus, formation, Image, formation, 7426352.html, Patent, pto, 7426352

Title: Image formation apparatus

Abstract: An image formation apparatus includes an automatic adjustment unit for automatic adjustment of the apparatus, a job queuing unit for queuing image formation jobs, a counting unit for counting the number of pages from the previous automatic adjustment for each automatic adjustment unit, and a determining unit for determining whether the number of image formation pages for automatic adjustment will be reached during the execution of the image formation queued job. In the event that the determining unit determines that the number of image formation pages for automatic adjustment will be reached during execution of the image formation job queued by the job queuing unit, automatic adjustment is performed before starting execution of the image formation queued job, even though the number of image formation pages counted by the counting unit has not reached the number for the automatic adjustment.

Patent Number: 7,426,352 Issued on 09/16/2008 to Moriyama, et al.

Inventors: Moriyama; Tsuyoshi (Ibaragi, JP), Fukushi; Kenji (Ibaragi, JP), Mizuno; Yoshio (Chiba, JP), Hashimoto; Tatsuaki (Chiba, JP)
Assignee: Canon Kabushiki Kaisha (Tokyo, JP)

Appl. No.: 10/691,516

Filed: October 24, 2003

Foreign Application Priority Data


Oct 24, 2002 [JP]			2002-309718
Oct 24, 2002 [JP]			2002-309719

Current U.S. Class: 399/43 ; 358/1.14; 358/406; 399/9

Current International Class: G03G 15/00 (20060101); G06F 15/00 (20060101); H04N 1/00 (20060101)

Field of Search: 399/43,50,51,53,66,9,49,301 358/1.14,406

References Cited [Referenced By]

U.S. Patent Documents


5546161	August 1996	Sakai et al.
5905581	May 1999	Suzuki et al.
5950036	September 1999	Konishi
6122461	September 2000	Shinohara

Foreign Patent Documents


63-43169	Feb., 1988	JP
63-147177	Jun., 1988	JP
63-280275	Nov., 1988	JP
1-261668	Oct., 1989	JP

Primary Examiner: Gray; David M
Assistant Examiner: Wong; Joseph S.
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper & Scinto

Claims

What is claimed is:

1. An image formation apparatus for forming images based on input image data, comprising: an automatic adjustment portion adapted to perform automatic adjustment of said image formation apparatus for each of a plurality of adjustment items; a job queuing portion adapted to queue image formation jobs; a counting portion adapted to count the number of image formations executed after a last automatic adjustment for each of said plurality of adjustment items; a determining portion adapted to determine, for each of said plurality of adjustment items, whether or not the number of image formations at which said automatic adjustment is to be performed by said automatic adjustment portion will be reached during execution of a next image formation job queued by said job queuing portion, based on the number of image formations counted by said counting portion, a number of image formations to be executed by said next image formation job queued by said job queuing portion and each of a plurality of thresholds set for each of said plurality of adjustment items; and a control portion adapted to control said automatic adjustment portion to perform the automatic adjustment based on the result of the determination by said determining portion, wherein in the event that said determining portion determines that there is at least one of said plurality of adjustment items for which said automatic adjustment is to be performed by said automatic adjustment portion during execution of said next image formation job queued by said job queuing portion, said control portion controls said automatic adjustment portion to perform the automatic adjustment before starting execution of said next image formation job queued by said job queuing portion even though the number of image formations counted by said counting portion has not reached the number at which said automatic adjustment is to be performed by said automatic adjustment portion.

2. An image formation apparatus according to claim 1, wherein said determining portion determines at least one of said plurality of adjustment items for which said automatic adjustment is to be performed by said automatic adjustment portion during execution of said next image formation job queued by said job queuing portion, by determining whether or not the sum of the number of image formations counted by said counting portion and the number of image formations of the next image formation job queued by said job queuing portion is greater than each of said plurality of thresholds set for each of said plurality of the adjustment items.

3. An image formation apparatus according to claim 1, wherein said plurality of adjustment items include at least density adjustment, which forms an image for density detection and determines density of said image for density detection and at least one other adjustment item.

4. An image formation apparatus according to claim 3, wherein said at least one other adjustment item is registration adjustment, which forms an image for position detection and determines position of said image for position detection.

5. An image formation apparatus according to claim 3, wherein said at least one other adjustment item is cleaning adjustment.

6. An image formation apparatus according to claim 3, wherein said at least one other adjustment item is resist adjustment.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image formation apparatus having functions for automatic adjustment or maintenance.

2. Description of the Related Art

In some cases, these types of conventional image formation apparatuses have a problem in that image density changes due to the change in a photosensitive member and a developing device over time, or due to the change in the temperature or humidity in the environment where the apparatus has been situated. As a countermeasure for the above-described problem, various proposals have been made with regard to a technique wherein parameters having an influence upon the image density of a toner image, e.g., a charging bias, a developing bias, and so forth, are adjusted at a suitable timing, thereby stabilizing the image density. For example, in a case of forming a color image using multiple image carrying members, a method of controlling toner density (Japanese Patent Laid-Open No. 63-147177), and a method of controlling an exposure amount (Japanese Patent Laid-Open No. 63-280275), are known wherein control is performed based upon detected information with regard to a predetermined pattern (test patch) transferred onto transfer means such as a common transfer belt or the like for transferring each visible image on the image carrying member onto a transfer member.

Furthermore, a method is known wherein the aforementioned test patch is transferred onto the transfer means, the density thereof is measured, and one of multiple process parameters relating to the image formation means is adjusted based thereupon (Japanese Patent Laid-Open No. 63-43169).

Furthermore, a method is known wherein exposure is made with various exposure amount in the range corresponding to the change in the light-portion potential estimated from the change in the environment, and the light-portion potential, which is to be a standard maximal density, is estimated based upon the pattern formed of the portions of different light-portion potential transferred onto the transfer means (Japanese Patent Laid-Open No. 1-261668). Furthermore, in addition to the above-described, a method is known wherein the change in the size of one dot is measured from the positional deviation of the pattern on the transfer means, and the process parameters such as an exposure period, output, a developing bias, and the like, are adjusted based upon the measurement results so as to maintain the suitable size of one dot (Japanese Patent Laid-Open No. 63-280275).

However, the above-described conventional image formation apparatuses have a problem in that in the event that the total count reaches a predetermined threshold number during processing, even for a job having just a few copies, the image formation apparatus enters an adjustment mode such as a density adjustment mode, leading to a problem of increase of time for processing the jobs beyond the anticipation of the user. There has also been a problem in that in the event that the image formation apparatus enters an adjustment mode, the tone or the like of the image formed may not be the same before and after the adjustment.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an image formation apparatus to solve the above-described problems.

To this end, according to a first aspect of the present invention, an image formation apparatus for forming images based on input image data comprises: an automatic adjustment unit for performing automatic adjustment of the image formation apparatus; a job queuing unit for queuing image formation jobs; a counting unit for counting the number of image formation pages from the previous automatic adjustment, for each automatic adjustment item which the automatic adjustment unit performs; a determining unit for determining whether or not the number of image formation pages at which the automatic adjustment is to be performed by the automatic adjustment unit will be reached during execution of the image formation job queued by the job queuing unit, based on the number of image formation pages counted by the counting unit and the image formation job queued by the job queuing unit; and a control unit wherein, in the event that the determining unit determines that the number of image formation pages at which the automatic adjustment is to be performed by the automatic adjustment unit will be reached during execution of the image formation job queued by the job queuing unit, automatic adjustment is performed by the automatic adjustment unit before starting executing of the image formation job queued by the job queuing unit even though the number of image formation pages counted by the counting unit has not reached the number at which the automatic adjustment is to be performed by the automatic adjustment unit.

According to a second aspect of the present invention, an image formation apparatus for forming images based on input image data comprises: an automatic adjustment unit for performing automatic adjustment of the image formation apparatus; a counting unit for counting the number of image formation pages from the previous automatic adjustment, for each automatic adjustment item which the automatic adjustment unit performs; a control unit for effecting automatic adjustment by an automatic adjustment unit, in response to the number of image formation pages counted by the counting unit reaching a first threshold value; a setting unit for setting a second threshold value smaller than the first threshold value; and a determining unit for determining whether or not the number of image formation pages counted by the counting unit have reached the second threshold value set by the setting unit before starting execution of the next image formation job; wherein, in the event that the determining unit determines that the number of image formation pages counted by the counting unit have reached the second threshold value, the control unit effects automatic adjustment by the automatic adjustment unit before starting executing of the next image formation job even though the number of image formation pages counted by the counting unit has not reached the first threshold value.

According to a third aspect of the present invention, an image formation apparatus for forming images based on input image data comprises: an automatic adjustment unit for performing automatic adjustment of the image formation apparatus; a counting unit for counting the number of image formation pages from the previous automatic adjustment, for each automatic adjustment item which the automatic adjustment unit performs; a control unit for effecting automatic adjustment by an automatic adjustment unit, in response to the number of image formation pages counted by the counting unit reaching a first threshold value; a setting unit for setting a second threshold value smaller than the first threshold value; and a determining unit for determining, at the time of an interruption of an image formation job, whether or not the number of image formation pages counted by the counting unit have reached the second threshold value set by the setting unit; wherein, in the event that the determining unit determines that the number of image formation pages counted by the counting unit have reached the second threshold value, the control unit effects automatic adjustment by the automatic adjustment unit before resuming from the interruption of the image formation job even though the number of image formation pages counted by the counting unit has not reached the first threshold value.

According to a fourth aspect of the present invention, an image formation apparatus for forming images based on input image data comprises: an acquiring unit for acquiring indicators relating to the time for performing the next maintenance for predetermined maintenance items; and a display unit for displaying indicators acquired by the acquiring unit for each maintenance item, along with the amount of time required for the maintenance.

According to a fifth aspect of the present invention, an image formation apparatus for forming images based on input image data comprises: an acquiring unit for acquiring indicators relating to the time for performing the next maintenance for predetermined maintenance items; and a display unit for displaying indicators acquired by the acquiring unit for each maintenance item; wherein the acquiring unit comprises a counting unit for counting the number of image formation sheets from the point that the previous maintenance ended for each maintenance item, and a calculating unit for calculating the number of remaining image formation sheets to the next maintenance, based on the counted number of image formation sheets, whereby the calculated number of remaining image formation sheets is acquired as the indicator.

According to a sixth aspect of the present invention, an image formation apparatus for forming images based on input image data comprises: an acquiring unit for acquiring indicators relating to the time for performing the next maintenance for predetermined maintenance items; a display unit for displaying indicators acquired by the acquiring unit for each maintenance item; a selecting unit for selecting the maintenance items based on the indicators displayed for each of the maintenance items; and a control unit for controlling the start of maintenance corresponding to a selected maintenance item.

According to a seventh aspect of the present invention, an image formation apparatus for forming images based on input image data comprises: an acquiring unit for acquiring indicators relating to the time for performing the next maintenance for predetermined maintenance items; a display unit for displaying indicators acquired by the acquiring unit for each maintenance item; a transmission unit for transmitting indicators acquired for each of the maintenance items to other apparatuses; a reception unit for receiving maintenance items selected by the other apparatuses based on the transmitted indicators; and a control unit for controlling the start of maintenance corresponding to the received maintenance items.

Due to the above configurations, the downtime due to adjustment can be reduced at the time of performing jobs. That is to say, the user can easily confirm the adjustment item which could be performed during the next job, in idle time up to the next job, at the time of turning on the power supply, or the like. Also, in the event that there is time up to the next job, the user can perform adjustment beforehand. Further, the user can select multiple adjustment items, and accordingly, the selected multiple adjustment items can be performed at the same time, thereby markedly reducing the downtime due to adjustment during the job.

Furthermore, multiple image formation apparatuses are connected through a network, and accordingly, the user can easily confirm the adjustment item of any image formation apparatus, which could be performed during the next job, from another image formation apparatus, and moreover, the user can give adjustment instructions for the image formation apparatus from the another one. thus, the user can give adjustment instructions for any image formation apparatus connected to the network from another image formation apparatus, so even in the event that the image formation apparatuses are situated distant one from another, the user can perform adjustment without the user moving to the distant image formation apparatus.

Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments (with reference to the attached drawings).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram which illustrates a configuration of an image formation apparatus according to a first embodiment.

FIG. 2 is a block diagram which illustrates a configuration of an image processing unit 312.

FIG. 3 is a diagram which illustrates a configuration of an LED image recording unit.

FIG. 4 is a diagram which illustrates a electronic configuration of a printer unit 300.

FIG. 5 is a diagram which illustrates a configuration of a density sensor.

FIG. 6 is a diagram for describing the density sensor 971 detecting the density of a patch P formed on a density belt 333.

FIG. 7 is a diagram which illustrates a configuration of a registration sensor.

FIG. 8 is a diagram which illustrates a configuration of a finisher 400.

FIG. 9 is a diagram which illustrates an external view of an operation display unit 550.

FIG. 10 is a flowchart which shows steps for execution processing for the adjustment mode.

FIG. 11 shows a table which indicates queuing of jobs.

FIG. 12 shows a table which indicates a threshold value X, a present count Y, a remaining number of pages, and the like, for each adjustment item.

FIG. 13 is a flowchart which shows steps for execution processing for the adjustment mode according to a second embodiment.

FIG. 14 shows a table which indicates a threshold value X, a second threshold value X2, and a present count value Y, for each adjustment item.

FIG. 15 is a flowchart which shows steps for execution processing for the adjustment mode according to a third embodiment.

FIG. 16 is a flowchart which shows steps for update processing for the second threshold value according to a fourth embodiment.

FIG. 17 is a circuit diagram which illustrates a configuration of a video signal count unit 220.

FIG. 18 shows a table which indicates the second threshold values.

FIG. 19 is a diagram which illustrates a configuration of an image formation system according to an embodiment.

FIG. 20 is a diagram which illustrates a configuration of another image formation system.

FIG. 21 is a diagram which illustrates an external view of the operation display unit 550.

FIG. 22 is a diagram which illustrates a maintenance management screen displayed on the operation display unit 550.

FIG. 23 is a diagram which illustrates an adjustment screen displayed on the operation display unit 550.

FIG. 24 is a diagram which illustrates a threshold change screen displayed on the operation display unit 550.

FIG. 25 is a diagram which illustrates a status screen displayed on the operation display unit 550.

FIG. 26 is a diagram which illustrates a list screen for expendables displayed on the operation display unit 550.

FIG. 27 is a flowchart which shows steps for adjustment execution processing performed at the time of the user selecting a maintenance key 563 on the operation display unit 550 of the image formation apparatus.

FIG. 28 is a diagram which illustrates a configuration of a network.

FIG. 29 is a diagram which shows the flow of data on the network.

FIG. 30 is a diagram which illustrates a screen of a printer driver.

FIG. 31 is a diagram which illustrates a main screen of a web service provided within a document server 1102.

FIG. 32 is a diagram which illustrates a device display portion 1707.

FIG. 33 is a diagram which illustrates a job status display portion 1709.

FIG. 34 is a diagram which illustrates a job history display portion 1711.

FIG. 35 is a diagram which illustrates a device status tab 1702.

FIG. 36 is a flowchart which shows steps for adjustment execution processing at the time of performing adjustment mode following instructions from another image formation apparatus connected to the network.

FIG. 37 is a diagram which shows an item list for maintenance.

FIG. 38 is a diagram which shows an item list for maintenance.

FIG. 39 is a diagram which shows an item list for maintenance.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

FIG. 1 is a diagram which illustrates a configuration of an image formation apparatus according to a first embodiment. The image formation apparatus principally comprises a color reader unit 200, a printer unit 300, and a finisher unit 400.

[Color Reader Unit]

First, description will be made regarding the configuration of the color reader unit 200. Reference numeral 101 denotes a CCD, 311 denotes a board where the CCD 101 has been mounted, and 312 denotes an image processing unit. The image processing unit includes a circuit (not including the CCD 101) shown in FIG. 2, a binary conversion unit 201 shown in FIG. 3, video signal count units 220 through 223, and delay units 202 through 205.

Reference numeral 301 denotes a document table glass (platen), and 302 denotes a document feeder (DF). Note that instead of employing the document feeder 302, the image formation apparatus may have a configuration including a flat pressing plate. Reference numerals 303 and 304 denote light sources (halogen lamp or fluorescent lamp) for illuminating a document sheet. Reference numerals 305 and 306 denote curved reflectors for collecting the light from the light sources 303 and 304 to the document.

Reference numerals 307 through 309 denote mirrors, and 310 denotes a lens for collecting the reflected light or projected light from the document sheet onto the CCD 101. Reference numeral 314 denotes a carriage for storing the halogen lamps 303 and 304, curved reflectors 305 and 306, and a mirror 307. Reference numeral 315 denotes a carriage for storing mirrors 308 and 309. Reference numeral 313 denotes an interface for communicating with other IPUs (image processing units) or the like.

Note that the carriage 314 is automatically moved with a speed V, and the carriage 315 is automatically moved with a speed V/2 in the direction orthogonal to the electrical scanning (main scanning) of the CCD 101, i.e., auxiliary scanning is performed, whereby the entire face of the document sheet is scanned.

[Image Processing Unit]

FIG. 2 is a block diagram which illustrates a configuration of the image processing unit 312. The light from the light sources 303 and 304 is reflected by the document sheet on the document table glass 301, and the reflected light is introduced onto the CCD 101 so as to be converted to electric signals. With the CCD 101 comprising color sensors, an arrangement may be made wherein RGB color filters are disposed inline on a single-line CCD in the order of R, G, and B, an arrangement may be made wherein the CCD 101 comprises a three-line CCD with an R-filter, a G-filter, and a B-filter arrayed on each line of the CCD, an arrangement may be made wherein an on-chip filter is employed, or an arrangement may have a separate configuration for the filters and the CCD.

Upon electric signals (analog image signals) being input to the image processing unit 312 from the CCD 101, the electric signals are held as a sample by a first processing unit 102 (clamp, amplification, S/H, A/D), the dark level of the analog image signal is clamped to the standard potential, is amplified with a predetermined gain, and is subjected to A/D conversion. In A/D conversion, the analog signals are converted into 8-bit signals for each of R, G, and B.

A shading unit 103 performs shading correction and black correction for the RGB signals, following which the corrected signals are input to a second processing unit 104 (sampling time correction, MTF correction, document detection). First, description will be made regarding sampling-timing correction. In a case that the CCD 101 is a three-line CCD, the reading positions are different between the three CCD lines at the same sampling time, and accordingly, the delay time is calculated for each CCD line based upon reading speed, and sampling timing is corrected using the calculated delay time so that the reading positions of the three CCD lines become the same. With the MTF correction, the change in MTF due to the change in the reading speed or magnification is corrected. With the document detection, the size of the document sheet is detected by scanning the document sheet on the document table glass.

Upon the digital signals subjected to the above-described sampling-timing correction being input to an input masking unit 105, the input masking unit 105 performs correction with regard to the spectral sensitivity of the CCD 101, and the spectral properties of the light sources 303 and 304, and the curved reflectors 305 and 306. The input masking unit 105 outputs the corrected signals to a selector 106 for performing switching between the corrected signals and external signals through interfaces. The signals output from the selector 106 are input to a third processing unit 107 (color space compression, removal of background, log conversion) and a background removal unit 115.

The signals input to the background removal unit 115 are subjected to removal of the background, following which the signals are input to a black-character determination unit 116 for determining whether or not there are any black characters in the document, and the black-character determination unit 116 generates black-character signals from the document. As described above, the same output signals from the selector 106 are input to the third processing unit 107 for performing color-space compression. With the aforementioned color-space compression, first, determination is made whether or not the image signals read out are in the range which can be reproduced by the printer. Subsequently, in the event that the image signals are in the range, the image signals pass through this processing without change, otherwise, the image signals are corrected so that the image signals are in the range. Furthermore, the third processing unit 107 performs background removal processing, and logarithm conversion for converting the RGB signals into the CMY signals. The signals output from the third processing unit 107 is subjected to timing adjustment by the delay unit 108 so as to match the timing of the signals generated by the black-character determination unit 116.

The aforementioned two kinds of signals are subjected to removal of moire by a moire removal unit 109, and are subjected to magnification processing in the main-scanning direction by a magnification processing unit 110. Upon the signals subjected to the aforementioned processing by the magnification processing unit being input to a fourth processing unit 111 (UCR, masking, adjustment of black characters), the fourth processing unit 111 performs UCR processing wherein CMYK signals are generated from the CMY signals, performs masking processing wherein the generated CMYK signals are corrected into signals suitable for printout, and adjusts the CMYK signals based upon the determination signals generated by the black-character determination unit 116.

The signals subjected to the above-described processing by the fourth processing unit 111 are subjected to density adjustment by a .gamma. correction unit 112, following which the signals are subjected to smoothing or edge processing by a filter unit 113. The signals subjected to such processing are converted from eight-bit signals of into one-bit signals by the binary conversion unit 201. Binary conversion may be made with any of the dithering-method, the error-diffusion method, the improved error-diffusion method, and the like.

[Printer Unit]

Next, description will be made regarding a configuration of the printer unit 300. In FIG. 1, reference numeral 317 denotes a yellow image formation unit, 318 denotes a magenta image formation unit, 319 denotes a cyan image formation unit, and 320 denotes a black image formation unit. These image formation units have the same configuration, so description will be made regarding the yellow image formation unit 317 in detail, and description of other image formation units will be omitted.

With the yellow image formation unit 317, reference numeral 342 denotes a photosensitive drum for forming a latent image thereon due to the light from an LED array 210. Reference numeral 321 denotes a primary charger for charging the surface of the photosensitive drum 342 to a predetermined potential for preparing formation of latent images. Reference numeral 322 denotes a developing device for forming toner images by developing the latent images on the photosensitive drum 342. Note that the developing device 322 includes a sleeve 345 for applying a developing bias for developing. Reference numeral 323 denotes a transfer charger for performing discharge from the back of a transfer belt 333 so as to transfer the toner images on the photosensitive drum 342 onto a recording sheet or the like mounted on the transfer belt 333.

Next, description will be made regarding a process for forming images on a recording sheet or the like. The recording sheets stored in the cassettes 340 and 341 are supplied one by one by a pickup rollers 338 and 339, and are supplied onto the transfer belt 333 by feeding rollers 336 and 337. The supplied recording sheet is charged by a pickup charger 366. Reference numeral 368 denotes a transfer belt roller for driving the transfer belt 333, and makes up a pair along with the pickup charger 366 so as to charge the recording sheet or the like, whereby the recording sheet or the like is picked up onto the transfer belt 333. Reference numeral 367 denotes a leading-edge detector for detecting the leading edge of the recording sheet or the like on the transfer belt 333. Note that the detected signal from the leading-edge detector is transmitted to the color reader unit 200 from the printer unit 300 for using as an auxiliary scanning synchronous signal at the time of transmitting video signals from the color reader unit 200 to the printer unit 300.

Subsequently, the recording sheet or the like is transported by the transfer belt 333, and toner images are formed thereon by the image formation units 317 through 320 in the order of yellow (Y), magenta (M), cyan (C), and black (K). The recording sheet or the like output from the black image formation unit 320 is subjected to removal of charge by a charge-removal unit 349 in order to facilitate separation from the transfer belt 333, following which the recording sheet or the like is separated from the transfer belt 333. Reference numeral 350 denotes a separation charger for preventing deterioration of images due to separation discharge at the time of the recording sheet or the like separating from the transfer belt 333. The separated recording sheet or the like is charged by pre-fixing chargers 351 and 352 in order to prevent deterioration of images by assisting adsorption of the toner, following which a fixing device 334 performs thermal fixing for the toner images. Subsequently, the recording sheet or the like is transported to the finisher unit 400.

[LED Image Recording]

FIG. 3 is a diagram which illustrates a configuration of an LED image recording unit. As described above, the binary conversion unit 201, the video signal count units 220 through 223, and the delay unit 202 through 205 are included in the image processing unit 312. LED driving units 206 through 209 and LED units 210 through 213 are included in the image formation units of the yellow, magenta, cyan, and black, respectively.

The signals of Y, M, C, and K from the image processing unit 312 shown in FIG. 2 are converted into one-bit signals by the binary conversion unit 201, and are transmitted to the video signal count units 220 through 223 which are image information detecting means. The video signal count units 220 through 223 can count the total number of emission times of the LEDs for each color image.

Subsequently, the image signals subjected to binary processing are delayed by the delay units 202 through 205 corresponding to the distance between the leading-edge detector 367 and each of image formation positions, and are transmitted to the LED driving units 206 through 209. The LED driving units 206 through 209 generate signals for driving the LED units 210 through 213, respectively.

[Electric Configuration of the Printer Unit]

FIG. 4 is a diagram which illustrates an electric configuration of the printer unit 300. The printer unit 300 includes a CPU 15, ROM 11, RAM 12, EEPROM 13, a developing bias generating unit 14, a registration sensor 972, a density sensor 971, and the like. Furthermore, the CPU 15 is connected to an operating display unit 550 described later.

The ROM 11 stores programs and the like for being performed by the CPU 15. The RAM 12 temporarily stores control data for controlling the printer unit, calculated results from the CPU 15, and the like. The EEPROM (non-volatile memory) 13 stores for each adjustment item the numbers of copies (X1, X2, and so forth) from the preceding adjustment such as density adjustment, registration adjustment, and the like, up to the next adjustment as threshold values, and the numbers of copies (Y1, Y2, and so forth) from the preceding adjustment up to the present time. Furthermore, the EEPROM 13 stores adjustment values for the developing bias in the density adjustment, adjustment values for various sensors, and the like.

[Density Adjustment Processing]

Next, description will be made regarding density adjustment processing which is one of the adjustment modes (automatic adjustment or maintenance) described later. This processing is performed by the CPU 15 within the printer unit 300. In general, electrophotographic color image formation apparatuses have a problem in that, in the event that deviation of the image density occurs due to the change in the environment where the image formation apparatus is situated, the number of copies, or the like, copies cannot be made in normal color tone. With the present embodiment, density-detecting toner images (patches) P are formed on the transfer belt 333 for each color toner as test patterns (see FIG. 6), the density of each patch is detected by the density sensor 971, and image density control is performed by performing adjustment based upon the detected results.

FIG. 5 is a diagram which illustrates a configuration of the density sensor. The density sensor 971 comprises a light-emission device 2a such as an LED, a light-receiving device 2b such as a photodiode, and a holder 2c. The infrared light from the light-emission device 2a is illuminated onto the patch P on the transfer belt 333, and the reflected light from the patch P is measured by the light-receiving device 2b, whereby the density of the patch P is measured.

Note that the reflected light from the patch P includes the regular-reflection component and the diffused-reflection component. With the present invention, either a method for detecting the regular-reflection component or a method for detecting the diffused-reflection component may be employed. However, the method for detecting the regular-reflection component (see FIG. 7) has a problem in that the amount of light greatly changes due to the state of the surface of the transfer belt 333 which is a background of the patch, or the change in the distance between the density sensor 971 and the patch P, leading to difficulty in maintaining precision of detection. Accordingly, with the present embodiment, the method for detecting diffused reflected light is employed. Accordingly, as shown in FIG. 5, taking the normal I as a reference line, the density sensor 971 performs measurement with the illumination angle .alpha. onto the patch P of 45.degree., and the receiving angle .beta. from the patch P of 0.degree. so as to eliminate the regular reflected light from the light cast to the light-receiving device 2b, and so as to measure only the diffused reflected light.

FIG. 6 is a diagram for describing the density sensor 971 detecting the density of the patch P formed on the transfer belt 333. With the actual density detecting method for the patch P, a square pattern with the width of 14 mm and the height of 14 mm is employed as a pattern of the patch P. The patch pattern is a half-tone pattern subjected to a predetermined dithering processing. Taking the pattern formed by full exposure as 100%, the pattern employed in the present embodiment corresponds to around 60%.

Developing is performed with the developing bias generated by the developing generating unit 14 being changed for each predetermined spacing so as to form multiple patch patterns, and the density of each patch pattern is detected by the density sensor 971. The developing bias for forming a patch pattern with a predetermined density is calculated based upon the detected values. The bias value is calculated for each color, and the calculated developing bias values are used at the time of image formation. Such control is referred to as "developing bias control".

Furthermore, an arrangement may be made wherein developing is performed with a calculated and fixed developing bias value for a half-tone pattern subjected to a predetermined dithering processing with the tone (exposure amount) changed for each constant spacing so as to form multiple patch patterns, and the density of each patch pattern is detected by the density sensor 971. Furthermore, an arrangement may be made wherein the exposure amount is corrected at the time of dithering processing so as to obtain smooth tone based upon the detected values. The control is referred to as "half-tone control".

Note that the density of the patch pattern is calculated from subtraction of the signal values of the reflected light from only the background of the electrostatic transporting belt measured prior to density control from the signal values of the reflected light from the patch pattern formed on the belt.

The image density control is preferably performed at the time of turning the power supply on, at the time of replacement of expendables such as cartridges or the like, at the time of the number of copies reaching a predetermined number after performing the preceding image density control, or the like. Furthermore, the image density control may be performed following adjustment instructions from the operation display unit 550 described later at a timing specified by the user. Furthermore, the image density control may be performed at a timing performed according to a flowchart described later.

[Registration Adjustment Processing]

Next, description will be made regarding to the registration adjustment processing which is one of the adjustment modes (automatic adjustment or maintenance) described later. The image formation apparatus includes the registration sensor 972 (see FIG. 7) at the portion facing the transfer belt 333 within the main unit thereof. The tandem color image formation apparatus according to the present embodiment transfers toners in four colors onto the transfer member for each color, and mixes these color toners at the time of fixing so as to reproduce color images. That is to say, in the event that the colors are not overlaid in a precise manner at the time of transferring the toners onto the transfer member, color images cannot be obtained with the normal color tone.

Accordingly, with the present embodiment, registration detecting toner images (lines) are formed on the transfer belt 333 for each color toner as test patterns, the transfer position is detected by the registration sensor 972 for each color, and the start timing of formation of the electrostatic latent image by the laser scanning and exposure is adjusted based upon the detected results. The above-described processing is referred to as "registration control".

The same optical density sensor as with the density sensor 971 can be employed as the registration sensor 972. Note that with the registration control, the transfer position is detected from the change in the amount of the received light at the time of the line passing through the field of view of the registration sensor 972, and the start timing of formation of the electrostatic latent image is corrected with regard to time based thereupon.

Note that the image density control is performed in order to detect the difference in the density between the patches, and accordingly, the method of detecting the diffused reflection component is employed for obtaining stable detection of the reflected light. However, the registration control is performed in order to detect the change in the absolute value of the light amount at the time of the line passing through the field of view of the registration sensor, the registration sensor employing the regular-reflected-light detecting method, shown in FIG. 7, using the regular reflected light which has a great absolute value, is employed. FIG. 7 is a diagram which illustrates a configuration of the registration sensor.

That is to say, taking the normal I as a reference line, the registration sensor 972 performs measurement with the illumination angle a onto the patch P of 45.degree., and the receiving angle .beta. from the patch P of 45.degree.. As a result, the registration sensor 972 measures both the diffused reflected light and the regular reflected light, but the regular reflection component is incomparably greater than the diffused reflection component, and accordingly, contribution of the diffused reflection component is negligible. Note that either of the reflected-light detecting methods may be employed for the density detection and the registration detection. Accordingly, an arrangement may be made wherein both the density detection and the registration detection are performed using only one optical density sensor employing either the regular-reflected-light detecting method or the diffused-reflected-light detecting method for reducing costs.

The registration control is preferably performed at the time of the power supply being turned on, at the time of replacement of expendables such as a cartridge, electrostatic transporting belt, or the like, at the time of the number of copies reaching a predetermined number after performing the preceding registration control, or the like. Furthermore, the registration control may be performed at a timing specified by the user according to adjustment instructions from the operating display unit 550 described later.

[Configuration of the Finisher Unit 400]

FIG. 8 is a diagram which illustrates a configuration of the finisher unit 400. The sheet output from the fixing unit 334 of the printer unit 300 is transported to the finisher unit 400. The finisher unit 400 includes a sample tray 1101 and a stack tray 1102, for switching to a suitable tray according to the type of the job or the number of sheet which are to be discharged.

Two types of sort methods are known. One is the bin sort method wherein output sheets are distributed to multiple bins. The other is the shift sort method wherein output sheets are distributed for each job using the electronic sort function with the bin or the tray being shifted inwards. Thus, sorting can be realized. The electronic sort function is also referred to as a "collating function", wherein the document stored in large-size buffer memory included in the core unit is output in a desired page number order, so as to support sorting.

The group function is a function for distributing output sheets for each page, while sorting is a function for distributing output sheets for each job. Furthermore, an arrangement may be made wherein the output sheets which are to be discharged to the stack tray 1102 are stored for each job, and the stored sheets are bound by a stapler 1105 for each job immediately prior to discharging.

Furthermore, the finisher unit 400 includes a Z-folding device 1104 for folding a paper sheet in the shape of the letter Z, and a puncher 1106 for punching two or three holes for filing, on a path up to the aforementioned two trays. Each processing is performed according to the type of the job.

Furthermore, a saddle stitcher 1107 binds the output sheets at two portions on the center thereof, following which the sheets are nipped by the roller at the center portion thereof so as to form a booklet in folio such as a magazine, pamphlet, or the like. The booklet formed of the sheets bound by the saddle stitcher 1107 is discharged onto a booklet tray 1108. Furthermore, an arrangement may be made wherein gluing is performed for binding the sheets into a booklet, or an arrangement may be made wherein trim is performed so as to true up the end face opposite to the binding side after binding (both not shown).

An inserter 1103 transports sheets set on a tray 1110 to any of the trays 1101, 1102, and 1108, without passing through the printer. Thus, the sheet set to the inserter 1103 can be inserted between the sheets which are to be transported to the finisher unit 210.

Upon the user setting the sheets face up on the tray 1110 of the inserter 1103, the sheets are supplied by a pickup roller 1111 in order from the topmost sheet. The sheets are transported directly from the inserter 1103 to the tray 1101 or tray 1102, and are discharged face down. In the event of transporting the saddle stitcher 1107, the sheets are temporarily transported to the puncher 1106, following which the sheets are transported to the saddle stitcher 1107 so as to match the face direction of the sheets.

[Operating Display Unit]

FIG. 9 is a diagram which illustrates an external view of the operating display unit 550. The operating display unit 550 includes various kinds of key groups and a LCD (liquid crystal display) 551. The LCD 501 is formed of a touch panel of which the surface is transparent. Various kinds of messages can be displayed on the LCD 501, and furthermore, various kinds of input keys are displayed so that the user can input commands by pressing the input keys displayed thereon.

Of the input key groups, reference numeral 552 denotes a numerical keypad for inputting values such as the number of copies. Reference numeral 553 denotes a copy start key for starting copy. Reference numeral 554 denotes a stop key for stopping copy operations.

Reference numeral 555 denotes a copy density key for adjusting the copy density manually. Reference numeral 556 denotes an AE key for switching to the automatic mode wherein the copy density is automatically adjusted according to the density of the document, or canceling AE (automatic density adjustment) and switching to the manual mode wherein the copy density is manually adjusted.

Reference numeral 557 is a copy mode key for entering the copy mode. Note that the image formation apparatus includes the copy queuing function wherein upon the user setting the following document onto the document feeder (DF) 302 following the preceding document being read out, the document can be read out and queued as a next copy job, even during printout for the previous job. Reference numeral 559 denotes a fax mode key for performing the fax function.

Reference numeral 558 denotes a cassette selection key (sheet selection key) for selecting the upper cassette 341 or the lower cassette 340. In the event that the document is placed on the document feeder (DF) 302, the user can select APS (automatic paper selection) with the cassette selection key 558. In the event that APS is selected, the image formation apparatus automatically selects a cassette storing sheets of the same size as the document. Reference character 562 denotes a user mode key for the user changing the settings of the present image formation apparatus. The settings which can be changed by the user include how long the input settings are to be held from the time of the setting being input (the input settings are automatically cleared after this period), default settings of the mode at the time of the reset key being pressed, and the like, for example.

Reference numeral 562 denotes a key for selecting an operation mode for the finisher 400. Upon the user pressing the key 562, the LCD 551 displays the screen for selecting the staple mode, folding mode, or the like. Reference numeral 561 denotes an advanced mode key for performing settings of the advanced modes such as settings of the binding margin, photographic mode, multiple processing, dual page copying, 2 in 1 mode, and so forth.

[Adjustment Processing]

FIG. 10 is a flowchart which illustrates the processing steps executed for an adjustment mode. The processing program is stored in the ROM 11 within the printer unit, and is executed by the CPU 15. First, determination is made whether or not the job has ended (Step S101). In the event that the job has not ended, the processing in Step S101 is repeated. In the event that the job has ended, determination is made whether or not there are any subsequent jobs queued (Step S102). In the event that there are no subsequent jobs queued, the present processing ends.

On the other hand, in the event that there is a subsequent job queued, the image formation apparatus checks the details of the next job (Step S103). FIG. 11 shows a table indicating the queuing of the jobs. Here, the job 1 is running at the present time, job 2 is for printing 100 pages .times.2 copies, and job 3 is for printing 10 pages .times.50 copies. The number of total printing pages is confirmed in the analysis of the details of the next job.

Subsequently, determination is made whether or not the image formation apparatus has any adjustment items for the adjustment mode executed during the next job (Step S104). The determination is made as follows. With the threshold value for determining the time of next adjustment from the time of the preceding adjustment as X, and with the number of total copies from the time of the preceding adjustment up to the present time as Y (present count), the number of the remaining copies, which can be performed up to the next adjustment, is represented by X-Y. Note that the parameters such as the aforementioned threshold value X, present count Y, and the like, are stored in the EEPROM 13. With the number of total copies for the next job as Z, in the event that the relation represented by Expression (1) holds, the image formation apparatus determines that the total number of copies reaches the threshold for executing the adjustment mode during the next job. Z>X-Y (1)

FIG. 12 shows a table indicating the threshold values X, present count Y, remaining number of pages, and the like, for each adjustment item. As specific examples of the adjustment items, the density adjustment and the registration adjustment are shown in the table, but each image formation apparatus has particular adjustment items, and accordingly, it is needless to say that the adjustment items are not restricted to the examples.

In this table, the threshold values X are set to 500 pages for both adjustment modes. These threshold values are set to particular values for each image formation apparatus, but the user can change the threshold values with the operation display unit 550. In addition, the number of pages printed (present count) Y from the time of the preceding adjustment up to the present time are 450 pages and 200 pages for the density adjustment and the registration adjustment, respectively. Accordingly, the remaining number of pages (X-Y) wherein copies can be performed up to the next adjustment are 50 pages and 300 pages, respectively. Furthermore, the number of the total copies Z for the next job is 200 pages corresponding to the job 2 of the queued jobs shown in FIG. 11. Accordingly, the image formation apparatus determines whether or not the number of pages printed will reach the threshold for performing the adjustment mode during the next job by making determination whether or not the relation of Expression (1) holds. Here, the above-described relation holds with regard to the item of the density adjustment, and accordingly, the image formation apparatus determines that the number of pages printed will reach the threshold for executing the density adjustment during the next job. On the other hand, the above-described relation does not hold with regard to the item of the registration adjustment, and accordingly, the image formation apparatus determines that the number of pages printed will not reach the threshold for executing the adjustment mode during the next job.

In Step S104, in the event that determination is made that there are no adjustment mode items to be executed during the next job, the present processing ends. On the other hand, in the event that determination is made that the image formation apparatus has an item for the adjustment mode executed during the next job, the corresponding adjustment mode is executed (Step S105). As described above, here, the density adjustment mode is executed. Subsequently, determination is made whether or not the adjustment mode has ended (Step S106). In the event that determination is made that the adjustment mode has not ended, the processing in Step S106 is repeated. On the other hand, in the event that determination is made that the adjustment mode has ended, the corresponding present count Y (in this case, the count value for the density adjustment) is cleared (Step S107). Subsequently, the present processing ends.

In general, there is some time between the individual jobs for operations performed by the user, such as picking up the discharged sheets from the stack tray or the booklet tray of the finisher 400, supplying sheets for the next job, or the like. With the present embodiment, the adjustment mode of the adjustment item, wherein determination is made that the number of printed pages reaches the threshold for executing the adjustment mode during the next job, is executed between the individual jobs beforehand, thereby reducing the downtime during the job, and reducing the number of times of adjustment. Furthermore, adjustment is not executed during the job, thereby preventing difference in image quality between the copies before and after the execution of the adjustment mode within a single job. Furthermore, with the present embodiment, the adjustment mode is executed between the individual jobs, and accordingly, the adjustment mode is executed around the threshold for executing the adjustment mode, thereby obtaining excellent image quality.

Second Embodiment

FIG. 13 is a flowchart showing the processing steps executed for the adjustment mode according to a second embodiment. The processing program thereof is stored in the ROM 11 within the printer unit, and is executed by the CPU 15. First, determination is made whether or not the job has ended (Step S201). In the event that determination is made that the job has ended, the processing in Step S201 is repeated, otherwise determination is made whether or not the present count Y for each adjustment item is greater than the second threshold value X2 (Y>X2) (Step S202).

Note that the second threshold value X2 can be input by the user with the operation display unit 550, and is set to a value smaller than the threshold value (X) by a predetermined value. FIG. 14 shows a table indicating the threshold values (X), the second threshold values X2, and the present count values Y, for each adjustment item. In an example of the present embodiment, the second threshold values X2 is smaller than the threshold value X by 50 pages, respectively. Note that an arrangement may be made wherein the second threshold value X2 is automatically updated according to the details of the job in a predetermined period.

In Step S202, in the event that determination has been made that all the present count values Y of the adjustment items are equal to or less than the second threshold values X2, respectively, the present processing ends. In this example, only the present count Y of the registration adjustment is less than the second threshold value X2 (Y<X2), and the present count Y of the density adjustment is greater than the second threshold value X2 (Y>X2).

In Step S202, in the event that determination is made that at least one of the present count values Y of the adjustment items is greater than the second threshold value X2, the corresponding adjustment mode (in this case, the density adjustment mode) is executed (Step S203). Note that in the event that the image formation apparatus has multiple required adjustment modes, the multiple adjustment modes are consecutively executed. Subsequently, the image formation apparatus waits for the processing to end (Step S204). In the event that the execution of the adjustment mode has ended, the present count Y is cleared in Step S205, and the present processing ends.

As described above, with the present embodiment, the user can set and change the second threshold values, and accordingly, the adjustment items for the adjustment modes which might be executed during the next job depending upon the density of a printout such as a character printout, solid picture printout, or the like, are found beforehand, and are executed before starting the job. Thus, the downtime during the job is reduced, and the number of times of adjustment is reduced.

Third Embodiment

FIG. 15 is a flowchart which shows the processing steps executed for the adjustment mode according to a third embodiment. The processing program thereof is stored in the ROM 11 within the printer unit, and is executed by the CPU 15. First, determination is made whether or not the job has been interrupted (Step S301). Here, interruption of the job means that the job has been interrupted to supply sheets, supply staples for the finisher, pick up the output sheets following detection of the stack tray being full, or the like, during the job.

In the event that determination is made that the job has not been interrupted, the processing in Step S301 is repeated. On the other hand, in the event that determination is made that the job has been interrupted, determination is made whether or not at least one of the present count values Y of the adjustment items is greater than the second adjustment value X2 (Step S302). Detailed description regarding the second threshold values X2 and the step processing has been made in the above second embodiment, so description thereof will be omitted.

In the event that all the present count values Y of the adjustment items are equal to or less than the second threshold values X2, respectively, the present processing ends. On the other hand, in the event that at least one of the present count values Y of the adjustment items is greater than the second threshold value X2, the corresponding adjustment mode is executed (Step S303). In FIG. 14, the item of the density adjustment matches the criteria, and accordingly the density adjustment mode is executed. Note that in the event that there are multiple required adjustment modes, the other required adjustment modes are consecutively executed.

Subsequently, determination is made whether or not the adjustment mode has ended (Step S304). In the event that the adjustment mode has not ended, the processing in Step S304 is repeated, otherwise the present count Y is cleared (Step S305). Subsequently, the processing ends.

With the present embodiment, any adjustment item of an adjustment mode which might be executed during the job can be found even during the job, and the required adjustment mode is executed during an interruption of the job, and accordingly, the brief periods during interruption of jobs can be efficiently us