JP2016090731A - Control method and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the occurrence of downtime of an apparatus caused by expansion of an interpage area in imaging condition adjustment processing.SOLUTION: A control part is configured to execute the following processing. Imaging condition adjustment processing is performed in parallel with imaging processing of forming images based on imaging information input to an image information input part in image output areas of photoreceptors 11y, 11c, 11m, and 11b. In the imaging condition adjustment processing, a y test toner image, c test toner image, m test toner image, and b test toner image are formed in non-image output areas at the ends in the rotation axis direction of the photoreceptors 11y, 11c, 11m, and 11b, and are page corresponding areas in a surface movement direction (sub scanning direction).SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image forming apparatus and a control method used for a control unit of the image forming apparatus.

  Conventionally, the image density is stabilized by performing image forming condition adjustment processing for adjusting the image forming condition of the image forming means based on the result of detecting the toner adhesion amount of the test toner image formed by the image forming means. There is known an image forming apparatus designed to achieve the above.

  The image forming apparatus described in Patent Document 1 performs such image forming condition adjustment processing as follows. In other words, the image forming apparatus is configured such that an image based on image information is provided on each of both ends in the photosensitive body rotation axis direction from an image output area for forming an image based on image information on the surface of the photoconductor as an image carrier. A non-image output area in which no image is formed is provided. After the test toner image formed on the non-image output area of the photoconductor is primarily transferred to the test image transfer area existing at the end in the width direction of the intermediate transfer belt, which is a transfer body, the toner adhesion amount of the test toner image is reflected. Detected by a mold optical sensor. Next, based on the detection result of the toner adhesion amount, a value capable of obtaining a desired toner adhesion amount (image density) for the development bias as an image forming condition is specified, and image forming processing is performed based on a user command The development bias at the time of adjustment is adjusted to a specified value.

  The secondary transfer roller that contacts the intermediate transfer belt to form the secondary transfer nip to transfer the image formed based on the user's command from the intermediate transfer belt to the recording sheet is only for the image transfer area of the intermediate transfer belt. It is the length which touches. The test toner image formed in the test image transfer area of the intermediate transfer belt that is not in contact with the secondary transfer roller passes through the side of the secondary transfer nip as the belt moves, and is then removed by the cleaning device. With this configuration, it is possible to reduce the cost by omitting the contact / separation mechanism for bringing the secondary transfer roller into and out of contact with the intermediate transfer belt with the aim of avoiding the transfer of the test toner image to the secondary transfer roller.

  However, this image forming apparatus has a problem that the downtime of the apparatus is increased by performing the image forming condition adjustment process. Specifically, in continuous printing in which images are continuously formed on a plurality of recording sheets, an area corresponding to a recording sheet conveyed in advance and an area corresponding to a subsequent recording sheet on the surface of the photoreceptor. In between, a region between pages corresponding to a gap between sheets is generated. In this image forming apparatus, a plurality of test toner images are formed in the non-image output area corresponding to the inter-page area in the surface movement direction of the photoreceptor. Then, in order to make it possible to form a plurality of test toner images arranged in the surface movement direction, the inter-page area is expanded only when the image forming condition adjustment process is performed. This increases the downtime of the device.

  In order to solve the above-described problems, the present invention includes an image information acquisition unit that acquires image information, an image output region in which an image based on the image information is formed, and a non-image output region in which the image is not formed. An image carrier provided so as to be aligned in a direction orthogonal to the surface movement direction of the image carrier, an image forming means for forming a toner image on the moving surface of the image carrier, and a toner image on the image carrier. A transfer means for transferring to the surface of the transfer body; and an adhesion amount detection means for detecting a toner adhesion amount of a test toner image transferred to the transfer body by the transfer means after being imaged in the non-image output area; An image forming condition adjustment process is performed in which the test toner image is formed in the non-image output region and the image forming condition of the image forming unit is adjusted based on the result of detecting the toner adhering amount by the adhering amount detecting unit. Control means to In the image forming apparatus, the test for performing the image forming condition adjustment process in parallel with the image forming process for forming an image based on the image information in the image output area and forming the image in the non-image output area. The control means is configured to form a toner image side by side with the image to be formed in the image output area in the orthogonal direction.

  According to the present invention, there is an excellent effect that it is possible to suppress the occurrence of apparatus downtime due to the expansion of the inter-page area for the image forming condition adjustment processing.

1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment. FIG. 3 is an enlarged configuration diagram illustrating an image forming unit for y, an intermediate transfer belt, and a primary transfer roller for y in the image forming apparatus. FIG. 2 is a block diagram showing a part of an electric circuit of the image forming apparatus. FIG. 3 is a plan view showing an intermediate transfer unit in which a test pattern image is formed on the intermediate transfer belt. The side view which shows the outline of the transfer unit. 6 is a flowchart showing a processing flow of control performed by a control unit of the image forming apparatus. The graph which shows the relationship between the image area rate [%] in a nip, and the primary transfer rate [%] of a toner image. The plane schematic diagram for demonstrating the relationship between a virtual matrix, a page, and the number of pixels. FIG. 4 is a schematic plan view for explaining an image portion output to an image output region, a test toner image output to a non-image output region, and a selection mode of an image forming section of the test toner image. FIG. 4 is a schematic plan view for explaining an image portion output to an image output area, a test toner image output to a non-image output area, and a selection mode of the size of the test toner image. FIG. 6 is a schematic plan view for explaining an aspect in which the image forming position of the test toner image is shifted to the inter-page area. 6 is a graph showing the relationship between the output voltage from the reflective optical sensor and the timing for detecting each part of the test toner image. 6 is a graph showing the relationship between the primary transfer rate, the image area ratio in the nip, and the charging potential of the photoreceptor. 6 is a graph showing the relationship between the reverse transfer rate at the downstream primary transfer nip and the charging potential of the downstream photoconductor. 9 is a flowchart illustrating a processing flow of target toner density correction processing performed by a control unit of an image forming apparatus according to a third embodiment.

Hereinafter, embodiments of an image forming apparatus to which the present invention is applied will be described.
FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment. In the figure, an image forming unit 10y, 10c, 10m, 10b for forming yellow, cyan, magenta, and black toner images is provided in a housing 101 of the image forming apparatus. Note that the subscripts y, c, m, and b added after the reference numerals indicate members for yellow, cyan, magenta, and black.

  Above the image forming units 10y, 10c, 10m, and 10b, an intermediate transfer unit 50 having an endless intermediate transfer belt 15 and the like is disposed. The four image forming units 10y, 10c, 10m, and 10b are arranged so as to be aligned along the surface movement direction while facing the front surface of the intermediate transfer belt 15 as a transfer body. The image forming units 10y, 10c, 10m, and 10b are provided around the drum-shaped photoconductors 11y, 11c, 11m, and 11b serving as image carriers, and charging members 12y, 12c, 12m, and 12b, and developing devices 14y, 14c, 14m, and 14b. Moreover, it also has primary cleaning devices 17y, 17c, 17m, and 17b.

  The surfaces of the photoreceptors 11y, 11c, 11m, and 11b that rotate in the clockwise direction in the figure are uniformly charged by the charging members 12y, 12c, 12m, and 12b of the charging device for y, c, m, and b. The charging device for y, c, m, and b generates a discharge between the charging members 12y, 12c, 12m, and 12b to which a charging bias is applied and the photosensitive members 11y, 11c, 11m, and 11b. The surfaces of 11y, 11c, 11m, and 11b are uniformly charged.

  A latent image writing device 13 is disposed below the image forming units 10y, 10c, 10m, and 10b. The latent image writing device 13 is a photoconductor 11y, 11c, 11m, 11b by optical scanning with laser light Ly, Lc, Lm, Lb generated based on image information sent from a personal computer, scanner, etc. (not shown). The electrostatic latent images for y, c, m, and b are written in The electrostatic latent images for y, c, m, and b are developed by developing devices 14y, 14c, 14m, and 14b to become a y toner image, a c toner image, an m toner image, and a b toner image. These toner images are sequentially superimposed on the surface of the intermediate transfer belt 15 and primarily transferred to form a four-color superimposed toner image.

  Inside the loop of the intermediate transfer belt 15, four primary transfer rollers 16y, 16c, 16m, and 16b, a detection backup roller 31, a secondary transfer backup roller 51, a cleaning backup roller 52, a tension roller 53, and the like are disposed. . The intermediate transfer belt 15 is stretched around these rollers.

  The intermediate transfer belt 15 is sandwiched between the primary transfer rollers 16y, 16c, 16m, and 16b to which a primary transfer bias is applied by a power source (not shown) and the photoreceptors 11y, 11c, 11m, and 11b. As a result, primary transfer nips for y, c, m, and b in which the photoreceptors 11y, 11c, 11m, and 11b abut on the front surface of the intermediate transfer belt 15 are formed. The front surface of the intermediate transfer belt 15 that is endlessly moved in the counterclockwise direction in the figure passes through the primary transfer nip for y, c, m, and b, and is used as a y toner image, a c toner image, and a m toner. The image and the b toner image are superposed in order and are primarily transferred.

  The secondary cleaning device 18 is in contact with the cleaning transfer roller 52 on the intermediate transfer belt 15 from the belt front surface side. Further, the secondary transfer roller 25 is in contact with the secondary transfer backup roller 51 on the intermediate transfer belt 15 from the belt front surface side to form a secondary transfer nip. The transfer unit 50 including members disposed around the belt, the intermediate transfer belt 15, and various members disposed inside the loop can be attached to and detached from the housing 101 integrally. It has become.

  The transfer unit 50 also includes an optical sensor unit 30 disposed outside the belt loop. The optical sensor unit 30 is opposed to a portion where the intermediate transfer belt 15 is wound around the detection backup roller 31 with a predetermined gap. Then, a toner adhesion amount per unit area of a later-described test toner image formed on the front surface of the intermediate transfer belt 15 is detected, and the result is output to a control unit (not shown).

  A sheet feeding cassette 21 that stores a plurality of recording sheets P in a bundle of sheets is disposed below the casing 101. A paper feeding device 20 is disposed in the vicinity of the paper feeding cassette 21. The paper feeding device 20 feeds the recording sheet P in the paper feeding cassette 21 to the paper feeding path 23 by starting rotational driving of the feeding roller at an appropriate timing. The fed recording sheet P is temporarily stopped at the timing when it comes into contact with the registration nip of the registration roller pair 24 forming a registration nip by bringing the two rollers into contact with each other. Thereafter, when the registration roller pair 24 starts to rotate at an appropriate timing, the recording sheet P is sent to the secondary transfer nip via the registration nip. A secondary transfer electric field is formed in the secondary transfer nip positioned between the secondary transfer backup roller 51 to which the secondary transfer bias is applied and the grounded secondary transfer roller 25. On the recording sheet P that has entered the secondary transfer nip, a four-color superimposed toner image is secondarily transferred to a full-color toner image by the action of the nip pressure and the secondary transfer electric field.

  The recording sheet P that has passed through the secondary transfer nip enters the fixing device 22 disposed above the secondary transfer nip. Then, the toner enters a fixing nip by contact between the fixing roller containing the halogen lamp and the pressure roller, and is heated and pressurized. By this heating and pressurization, the full color toner image is fixed on the surface of the recording sheet P.

  The recording sheet P that has passed through the fixing device 22 passes through the paper discharge path and is then discharged out of the apparatus by the discharge roller 26. Then, it is stacked on a stack tray 27 provided on the upper surface of the casing 101.

  The transfer residual toner is removed from the surfaces of the photoreceptors 11y, 11c, 11m, and 11b after passing through the primary transfer nips for y, c, m, and b by the primary cleaning devices 17y, 17c, 17m, and 17b. Further, the transfer residual toner is removed from the front surface of the intermediate transfer belt 15 after passing through the secondary transfer nip by the secondary cleaning device 18.

  Below the stack tray 27, bottle storage portions for storing toner bottles 28y, 28c, 28m, and 28b containing y toner, c toner, m toner, and b toner are disposed. The y toner, c toner, m toner, and b toner accommodated in the toner bottles 28y, 28c, 28m, and 28b are driven by a toner replenishing device for y, c, m, and b (not shown). 14c, 14m and 14b are replenished.

The four image forming units 10y, 10c, 10m, and 10b have different colors of toner to be used, but the other configurations are substantially the same. Therefore, the image forming process will be described below using the y image forming unit 10y as an example.
FIG. 2 is an enlarged configuration diagram illustrating the image forming unit 10y for y, the intermediate transfer belt 15, and the primary transfer roller 16y for y. In the figure, the control unit 150 controls the drive of the drive motor 34. The developing device 14y driven by the drive motor 34 contains a developer in which a magnetic carrier and y toner are mixed, and two screw members 14y-1, 14y- in which the developer is arranged in parallel. 2 is circulated and conveyed. On the circulation path of the circulation conveyance, a developing sleeve 14y-3 that includes a magnet roller (not shown) that cannot be rotated is disposed. The rotating developing sleeve 14y-3 carries the developer conveyed by the screw member 14y-2 on its surface by the magnetic force of the magnet roller. Then, the electrostatic latent image for y carried on the photoconductor 11y is developed while bringing the developer into contact with the photoconductor 11y as it rotates. The developer that has contributed to the development is returned onto the screw member 14y-2 as the developing sleeve 14y-3 rotates. Thereafter, the toner concentration is detected by a toner concentration sensor 14y-4 including a magnetic permeability sensor.

  FIG. 3 is a block diagram illustrating a part of an electric circuit of the image forming apparatus 100 according to the embodiment. The control unit 150 executes a sequence program related to image formation and performs arithmetic processing, and includes a microcomputer including a CPU (not shown) as arithmetic means, a ROM 151 and a RAM 152 as data storage means. As the RAM, a nonvolatile memory is used.

  In the input / output unit via an interface (not shown) of the control unit 150, toner density sensors 14y-4, 14c-4, 14m-4, 14b-4 for y, c, m, and b, and the latent image writing device 13 are provided. A paper feed motor 20a, a registration motor 24a, and the like are connected. An optical sensor unit 30, an image information input unit 151, a primary transfer power supply 161, a secondary transfer power supply 162, a development power supply 163, a charging power supply 164, and the like are also connected.

  The image information input unit 151 receives image information sent from an external personal computer or a scanner and transmits the image information to the control unit 150. The secondary transfer power source 162 outputs a secondary transfer bias to be applied to the secondary transfer backup roller 51.

  The primary transfer power supply 161 individually outputs primary transfer biases to be applied to the photoreceptors 11y, 11c, 11m, and 11b, and the primary transfer rollers 16y, 16c, 16m, and 16b. It is possible to output primary transfer biases corresponding to the respective colors y, c, m, and b by constant current control independent of each other.

  The developing power source 163 individually outputs a developing bias to be applied to each of developing sleeves for y, c, m, and b (for example, 14y-3). It is possible to output development biases individually corresponding to the respective colors for y, c, m, and b by constant voltage control independent of each other.

  The charging power source 164 individually outputs charging biases to be applied to the charging members 12y, 12c, 12m, and 12b for y, c, m, and b. It is possible to output charging biases individually corresponding to the colors for y, c, m, and b by constant voltage control independent of each other.

  In the image forming apparatus according to the embodiment, a combination of the image forming unit 10y for y and the latent image writing device 13 functions as an image forming unit for y. The combination of the c image forming unit 10c and the latent image writing device 13 functions as the c image forming means. The combination of the m image forming unit 10m and the latent image writing device 13 functions as an m image forming means. The combination of the b image forming unit 10b and the latent image writing device 13 functions as the b image forming means.

  The optical sensor unit 30 includes a first reflective optical sensor and a second reflective optical sensor (not shown). These reflective optical sensors irradiate both ends in the width direction of the intermediate transfer belt 15 with light emitted from the light emitting elements. Both end portions are non-image output areas in which images based on user commands (images based on image information input to the image information input unit 151) are not output. In this non-image output area, a test pattern image composed of a plurality of test toner images described later is formed. The reflection type optical sensor receives regular reflection light regularly reflected on the surface of the intermediate transfer belt 15 and the surface of the test toner image by the regular reflection light receiving element, and receives diffuse reflection light diffusely reflected by the diffuse reflection light receiving element. To do. The amount of received light has a correlation with the toner adhesion amount (image density) per unit area of the test toner image. Based on the output from the regular reflection type light receiving element and the output from the diffuse reflection type light receiving element, the control unit 150 determines the y toner adhesion amount, the c toner adhesion amount, and the m toner of the y, c, m test toner images. Know the amount of adhesion. Further, the b toner adhesion amount of the b test toner image is grasped based on the output from the regular reflection type light receiving element. The intermediate transfer belt 15 is made of a material that can sufficiently generate a difference between the reflected light amount on the surface and the reflected light amount on the test toner image.

  The control unit 150 performs a target toner density correction process as an image forming condition adjustment process during a continuous printing operation in which images are continuously formed on a plurality of recording sheets P. This target toner density correction process is a process for correcting the target toner density of the developer in the developing device to a value at which a desired image density can be obtained for each of the colors y, c, m, and b. The controller 150 drives the toner supply device so that the output voltage value from the toner density sensor (for example, 14y-4) matches a predetermined target output potential, thereby setting the toner density of the developer to the target toner density. It is almost matched. During the continuous printing operation, the target toner density is corrected by the target toner density correction process so that an image is formed with a stable image density even if the image forming ability fluctuates with a change in toner charge amount or temperature. Correct the target output potential. This correction is performed for each color of y, c, m, and b.

  When the control unit 150 starts the target toner density correction process during the continuous printing operation, first, a test pattern image including a y test toner image, a c test toner image, an m test toner image, and a b test toner image is intermediately transferred. The belt 15 is formed.

FIG. 4 is a plan view showing the intermediate transfer unit 50 in which a test pattern image is formed on the intermediate transfer belt 15. The length in the rotational axis direction of the roller portion of the secondary transfer roller 25 that contacts the intermediate transfer belt 15 to form the secondary transfer nip is considerably smaller than the width of the intermediate transfer belt 15 as shown in the figure. . Therefore, the secondary transfer nip, of the entire area in the width direction of the intermediate transfer belt 15, is formed in the nip region A ₃ except for the both end portions.

  The secondary transfer backup roller 51 and the secondary transfer roller 25 that sandwich the intermediate transfer belt 15 between the secondary transfer roller 25 and the secondary transfer roller 25 are arranged so that the centers of the roller portions in the rotational axis direction coincide with each other. Yes. As a result, the roller portion of the secondary transfer roller 25 abuts against the secondary transfer backup roller 51 with an equal pressure at one and the other with the center in the rotation axis direction as the boundary, and therefore in the width direction of the intermediate transfer belt 15. To prevent the vehicle from running off. When the center of the roller portion of the secondary transfer roller 25 in the rotational axis direction is shifted from the center of the roller portion of the secondary transfer backup roller 51 in the rotational axis direction, the one and the other are pushed. There is a difference in pressure. As a result, the belt traveling path on the side where the pressing force is large is shortened, so that the pulling force of the intermediate transfer belt 15 is increased, and the belt travels slightly.

In the intermediate transfer belt 15, both end portions in the width direction does not form a secondary transfer nip is adapted to the pattern transfer region A ₁ in which the test pattern image TP is primarily transferred. The test pattern image TP is obtained by arranging the y test toner image yT, the c test toner image cT, the m test toner image mT, and the b test toner image bT at predetermined intervals along the belt moving direction. Both end portions in the rotation axis direction of the photoreceptors of the respective colors (not shown) are non-image output areas that do not form an image based on a user command, and the test toner images (yT, cT, mT, bT) are non-images. after being imaged at the output region, it is primarily transferred to the pattern transfer region a ₁ of the intermediate transfer belt 15.

In the intermediate transfer belt 15, an image transfer area A ₂ for primary transfer of an image based on a user command is provided inside the nip area A ₃ . Image output region excluding the non-image output area of the photosensitive member of each color, not shown, the image transfer region A ₂ of the intermediate transfer belt 15 abuts to form a primary transfer nip. Is imaged in the image output area of the photoreceptor image is primarily transferred to the image transfer region A ₂ of the intermediate transfer belt 15 at the primary transfer nip. As shown in the figure, the belt width is larger than the nip area A ₃ > image transfer area A ₂ > pattern transfer area A ₁ × 2.

The test pattern image TP, as shown, each of which is formed in the pattern transfer region A ₁ in the both end portions of the intermediate transfer belt 15. As can be seen from the figure, the test pattern image TP is formed at a position that does not enter the secondary transfer nip, so that the secondary transfer roller 25 is not soiled with toner. Thereby, the contact / separation mechanism of the secondary transfer roller 25 with respect to the belt can be omitted, and the cost can be reduced.

  Each test toner image is formed in a size of vertical (dimension in the belt movement direction) = 15 [mm] × horizontal (dimension in the belt width direction) = 10 [mm], and between adjacent test toner images. There is a gap of 5 mm. Therefore, the length of the test pattern image TP in the belt moving direction is 15 × 4 + 5 × 3 = 75 [mm].

FIG. 5 is a side view schematically showing the transfer unit 50. The four photoconductors 11y, 11c, 11m, and 11b are disposed at intervals of a length L1 (= 100 mm) along the moving direction of the intermediate transfer belt 15. The length in the belt moving direction of the test pattern image TP composed of four test toner images (yT, cT, mT, bT) primarily transferred to the pattern transfer region (A ₁ ) of the intermediate transfer belt 15 is as described above. 75 [mm]. Of the primary transfer nips for y, c, m, and b, the primary transfer nip for b is located on the most downstream side in the belt moving direction (contact between the photoreceptor 11b and the intermediate transfer belt 15). It is. The distance from the center in the belt movement direction of the primary transfer nip for b to the center in the belt movement direction of the portion where the intermediate transfer belt 15 is wound around the tension roller 53 is also set to 75 [mm] (= L2). . The distance from the center to the center in the belt moving direction of the secondary transfer nip due to the contact between the intermediate transfer belt 15 and the secondary transfer roller 25 is also set to 75 [mm] (= L2).

As described above, the test pattern images TP primarily transferred to the pattern transfer regions (A ₁ ) at both ends in the width direction of the intermediate transfer belt 15 come into contact with the secondary transfer roller 25 as the belt moves. Without passing through the secondary transfer nip. Thereafter, as the belt moves, the amount of reflected light is detected when it passes directly under the optical sensor unit 30. The control unit 150 grasps the y toner adhesion amount of the y test toner image provided in the test pattern image TP based on the output voltage from the light receiving element of the optical sensor unit 30. Also, the c toner adhesion amount of the c test toner image, the m toner adhesion amount of the m test toner image, and the b toner adhesion amount of the b test toner image are grasped, and the grasping results are stored in the RAM 152.

Although only one test pattern image TP is shown in the drawing, the test pattern image TP is actually a pattern transfer region at one end in the width direction of the intermediate transfer belt 15 as shown in FIG. each of which is formed on the pattern transfer region a ₁ of the one end of the a ₁ and the other end portion. The amount of reflected light of the four test toner image on one side of the pattern transfer region A ₁ test pattern image formed on is detected by the first reflection-type optical sensor 30a. Further, the amount of reflected light of the four test toner image in the test pattern image formed on the pattern transfer region A ₁ on the other end side, is detected by the second reflective optical sensor 30b.

Control unit 150, the average value (adhesion amount of the toner adhering amount of the test toner image transferred to one of the pattern transfer region A _1, the toner adhering amount of the test toner image transferred to the other pattern transfer region A ₁ Average). Then, after obtaining a deviation amount which is a difference between the average adhesion amount and the target toner adhesion amount, an amount of toner adhesion is calculated using an algorithm indicating the relationship between the deviation amount and the voltage shift amount stored in advance in the RAM 152. The voltage shift amount that can eliminate the deviation is specified. Next, the value of the target output potential (target toner density) of the toner density sensor is shifted by the specified voltage shift amount. As a result, the toner density of the developer is corrected to a value at which a target image density can be obtained. Such a series of processes is performed for each of the colors y, c, m, and b.

  By performing such target toner density correction processing during the continuous printing operation, the image density in continuous printing can be stabilized. As the intermediate transfer belt 15 moves, the test pattern image TP that has passed immediately below the optical sensor unit 30 is removed from the belt surface by the cleaning device 18.

  When the target toner density correction process is performed, the inter-page area is expanded only when the target toner density correction process is performed in order to form the test pattern image TP in the inter-page area in the moving direction of the intermediate transfer belt. , Increase device downtime. If the test toner images of the respective colors are arranged in the belt width direction and the test pattern image TP is formed so as to extend in the belt width direction, it is not necessary to expand the inter-page region. However, it is necessary to provide a plurality of reflective optical sensors that individually detect the toner adhesion amount of each color test toner image, resulting in an increase in cost.

On the other hand, the image based on the user's command and the test pattern image are respectively formed in different areas (image output area and non-image output area) of the photoreceptor, and different areas (image transfer area A) of the intermediate transfer belt. _2. Transferred to the pattern transfer area A ₁ ). For this reason, it is possible to create an image based on the user's command next to the test pattern by performing image creation based on the user and image formation of the test pattern in parallel.

Therefore, the image forming apparatus according to the embodiment corrects the target toner density in parallel with the image forming process for forming an image based on the image information input to the image information input unit 151 due to a user command. Implement the process. Then, imaging the test pattern image TP photoreceptor (11y, 11c, 11m, 11b ) in the page corresponding region in and the surface moving direction of the rotation axis direction a non-image output area _{A 1} of the. In such a configuration, since the test pattern image TP is not formed in the inter-page area of the photoconductor, it is not necessary to expand the inter-page area. Therefore, the occurrence of device downtime can be suppressed.

  FIG. When the control unit 150 receives a print request signal accompanied by a continuous print operation (Y in Step 1; hereinafter, Step is referred to as S), the control unit 150 acquires image information sent from the image information input unit 151 (S2). Next, based on the image information, after starting the print job (S3), it is determined whether it is the execution timing of the target toner density correction process (S4). If it is not the execution timing (N in S4), it is determined whether or not all pages have been printed (S12). If there are remaining print jobs (N in S12), the processing flow is changed to S4. Loop. If all pages have been printed (Y in S12), the series of processing flow is terminated.

  If it is the execution timing of the target toner density correction process in S4 described above (Y in S4), the target toner density correction process is performed in parallel with the image forming process. First, conditions for generating the test pattern image TP are determined (S5). Examples of the generation condition include image formation start timing. Based on the delay time from the trigger signal in determining the image formation timing of the test pattern image TP, the number N of test toner images (4 in this example), the interval between the test toner images, the process linear velocity, etc. Determine the image formation start timing.

  Next, the control unit 150 determines a pattern reading condition (S6). Examples of the reading condition include a reading start timing and a reading method. The reading start timing is determined as a timing a little earlier than the time required from the start of latent image writing for the test pattern TP to the movement of the test pattern TP to the position of the optical sensor unit 30. This is because by starting sampling of the sensor output for the belt surface without the test pattern TP as a detection target, it is possible to grasp the change in the sensor output when the test pattern TP moves to the sensor position.

  Thereafter, the control unit 150 waits for the pattern generation timing (S7). At this time, the leading edge of the image area (asserts the FF gate) is used as a signal that triggers the start of image formation of the test pattern TP. When the image formation start timing comes, image formation of the test pattern image TP is started (S8), and the pattern reading timing is waited (S9). Then, a timer is started as the trigger signal is generated, and reading is started after a predetermined time (S10).

  FIG. 12 is a graph showing the relationship between the output voltage from the reflective optical sensor and the elapsed time at the time of reading. When the test toner image starts to enter the position of the optical sensor unit 30 facing the reflective optical sensor, the output voltage starts to change abruptly. Since the changing output voltage does not accurately reflect the toner adhesion amount, it is excluded from the reference data. The sampling data (peak data) corresponding to the center portion of the test toner image is identified from the size of the test toner image that is known in advance, and a predetermined number of dampling data before and after that is used to calculate the toner adhesion amount. Use. Data sampled at a timing of (x1 + x2) / 2 shown in the figure is peak data.

  The controller 150 that has calculated the toner adhesion amount then corrects the target toner concentration (target output potential) based on the difference between the calculation result of the toner adhesion amount and the target toner adhesion amount (S11).

  The example in which the target toner density correction process for adjusting the target toner density as the image forming condition and the image forming process are performed in parallel has been described. However, the image forming condition correction process and the image forming process different from the target toner density correction process are described. May be performed in parallel. For example, an image forming condition correction process is known as a process control process. In the process control process, the toner adhesion amount and the development potential are determined based on the results of grasping the toner adhesion amounts of a plurality of test toner images formed under different conditions of the development potential, which is the potential difference between the electrostatic latent image and the development bias. An approximate linear equation showing the relationship between Then, using an approximate linear equation, identify the development potential at which the target toner adhesion amount can be obtained, and adjust the development bias, laser writing intensity, charging bias, etc. as imaging conditions to values that realize that development potential. To do.

  Such a process control process may be performed in parallel with the image forming process. However, while it is necessary to form an image based on a user command with a constant development potential, a plurality of test toner images need to be formed with different development potentials. For this reason, for example, both end portions and the central portion in the rotation axis direction of the developing sleeve are insulated from each other, and both end portions (develop the non-image output area) and the central portion (develop the image output area) Therefore, it is necessary to devise such that individual development bias can be applied.

  In the image forming apparatus according to the embodiment, the image forming condition (target toner density in the embodiment) may be poorly adjusted depending on the shape of the image formed by the image forming process based on the user's command. Specifically, as in the image forming apparatus according to the embodiment, in the configuration in which the primary transfer bias is output by constant current control, a stable primary transfer is performed by flowing a constant primary transfer current to the primary transfer nip regardless of environmental changes. Performance can be demonstrated. On the other hand, the primary transfer rate of the toner to the intermediate transfer belt 15 greatly varies depending on the image area ratio of the image portion entering the primary transfer nip in the entire image (hereinafter referred to as an in-nip image area ratio). . Many of the images created based on the user's command have a complicated shape, so that the image area ratio in the nip varies greatly from the start to the end of the primary transfer of the toner image. . Due to this variation, four test toner images (yT, cT, mT, bT) of the test pattern TP formed in parallel with the image are primarily transferred to the intermediate transfer belt at different primary transfer rates. As a result, the toner adhesion amount of the test toner image that is primarily transferred onto the intermediate transfer belt does not accurately reflect the image forming performance of the image forming means, so the image forming performance cannot be accurately grasped. This causes poor adjustment of the image forming conditions (target toner density).

FIG. 7 is a graph showing the relationship between the in-nip image area ratio [%] and the primary transfer ratio [%] of the toner image. Table 1 below is a table showing the relationship between the range of the in-nip image area ratio [%] and the average primary transfer ratio [%] in the range. When the image area ratio in the nip is very low, the contact area between the photoconductor and the belt in the primary transfer nip is widened, and much of the primary transfer current flows to the contact area and does not contribute to the primary transfer of the toner image. As a result, the primary transfer rate is significantly reduced. Further, when the image area ratio in the nip is very high, a region where the insulating toner is interposed between the photosensitive member and the intermediate transfer belt 15 in the primary transfer nip becomes large, and the primary transfer current hardly flows. As a result, the primary transfer bias is greatly increased so as to obtain a target primary transfer current, and therefore, the toner charge amount is reduced and reverse charging is likely to occur due to the discharge between the photosensitive member and the intermediate transfer belt 15. As a result, the primary transfer rate is significantly reduced. For this reason, if the image area ratio in the nip is low or high as shown in the graph shown in the figure, the primary transfer ratio is remarkably lowered.

In FIG. 7, the area ratio constant composed of a combination of alphabet and number S indicating the image area ratio in the nip has a higher area ratio in the order of S ₁ <S ₂ <S ₃ <S ₄ <S ₅ <S _6. It will become. Then, as shown in Table 1, when obtaining the average primary transfer ratio of the range is limited to within a certain range the nip in an image area ratio, the area ratio constant S ₅ above, that the area ratio constant S less than ₆ The average primary transfer rate in the range is the highest. In the sub-scanning direction of the non-image output area of the photosensitive member (photosensitive member surface movement direction), the area ratio constant S ₅ above, if the image forming the test toner image on the position where the range of the area ratio constant S less than _6, the primary transfer The toner adhesion amount of the subsequent test toner image is a value that accurately indicates the image forming performance of the image forming means.

  Next, the image forming apparatus of each example in which a more characteristic configuration is added to the image forming apparatus according to the embodiment will be described. Note that the configuration of the image forming apparatus according to each example is the same as that of the embodiment unless otherwise specified.

[First embodiment]
The control unit 150 includes a main control unit and a writing control unit (not shown). The writing control unit controls the driving of the latent image writing device 13 while processing the image information sent from the image information input unit 151 and performs optical scanning of the photosensitive member with laser light. The main control unit performs other controls.

  When receiving the image information, the writing control unit performs a pixel count process. Specifically, as shown in FIG. 8, first, a page for outputting an image based on image information is virtually superimposed on a virtual matrix obtained by dividing the virtual surface area of the photoconductor into a matrix. The size of each square is n pixels × m pixels. In the same figure, the main scanning direction is the optical scanning direction when forming the latent image, and this is the same direction as the photosensitive member axial direction. The sub-scanning direction is the same direction as the photosensitive member surface moving direction.

  The writing control unit performs the following process for each of the colors y, c, m, and b in the pixel count process. That is, the number of square output pixels, which is the number of dots output in each square of the virtual matrix, is counted. Then, a square row composed of a plurality of squares arranged in the main scanning direction is defined as one division, and a division output pixel number that is the sum of the square output pixel numbers is calculated for each of the plurality of divisions arranged in the sub-scanning direction.

The writing control unit that has calculated the partition output pixel number of each partition by such pixel count processing next performs partition selection processing for each of the colors y, c, m, and b. In this section selection processing, first, a section where a test toner image (yT, cT, mT, bT) of the test pattern image TP is to be imaged is specified from among a plurality of sections in the virtual matrix. The partition output pixel number of the partition, i.e., about the size of the image portion to be imaged to the image output area of the partition, the nip in an image area ratio S area ratio constant S ₅ or more, less than the area ratio constant S ₆ It is determined whether the value falls within the range. If the value is within the above-described range, it is determined that a test toner image is to be created for the section. On the other hand, when the number of division output pixels is not a value that makes the image area ratio S in the nip within the above-described range, the division where the test toner image is scheduled to be formed is shifted backward by one division in the sub-scanning direction. Then, for the section, it is determined whether or not the number of section output pixels is a value that brings the in-nip image area ratio S into the above-described range. The same processing is repeated until a section having the number of section output pixels within the nip image area ratio S within the above-described range is found, and it is determined that a test toner image is formed for the section. For example, as shown in FIG. 9, when the image area ratio S in the nip of the section where image formation was planned is too low, the test toner image is displayed in the next section having the appropriate image area ratio S in the nip. Create an image.

  In such a configuration, a test is performed on an area that realizes a good primary transfer rate (a section where the number of divided output pixels sets the area ratio S in the nip to the above-described range) out of the entire non-image output area in the sub-scanning direction. A toner image is selectively formed. As a result, the toner adhesion amount of the test toner image primarily transferred to the intermediate transfer belt 15 is set to a value that accurately reflects the image forming performance of the image forming means, so that the electrostatic latent image can be accurately obtained at the target image density. The target toner density can be adjusted to a value that can be developed. Therefore, it is possible to suppress the occurrence of poor adjustment of the image forming condition (target toner density) due to the fluctuation of the in-nip image area ratio S.

  As for the number of divided output pixels, only the number of pixels in the image portion formed in the image output area of the divided portion may be counted, or in addition to the number of pixels in the image portion, the image is formed in the non-image output area. The number of pixels of the test toner image may also be counted.

  In addition, for c after the image forming start timing after y, in addition to the condition that the number of output pixels in the nip is the value that makes the image area ratio S in the nip within the above-mentioned range, the following conditions are also satisfied. , C is selected as an image formation target of the test toner image cT. That is, the condition is that the y test toner image yT moving from the upstream side is not synchronized in the primary transfer nip for c.

  In addition, for m after the image formation start timing after y and c, in addition to the condition that the image area ratio S in the nip is the number of divided output pixels having a value within the above range, the following condition is also satisfied. The section is selected as an image formation target of the m test toner image mT. That is, the condition is that the y test toner image yT and the c test toner image cT moving from the upstream side are not synchronized in the primary transfer nip for m.

  In addition, with respect to “b” whose image formation start timing is later than “y”, “c”, and “m”, in addition to the condition that the image area ratio S in the nip is the number of divided output pixels within the above range, the following condition is also satisfied: The provided section is selected as an image forming target of the b test toner image bT. That is, the condition is that the y test toner image yT, the c test toner image cT, and the m test toner image mT moving from the upstream side at the primary transfer nip for b are not synchronized.

Further, the scope of the nip in the image area ratio to the highest primary transfer ratio (area ratio constant S ₅ or more, the area rate constants less than S ₆₎ has been described for imaging the test toner image on the compartment differ from those A test toner image may be formed in the range. This is because, if a test toner image is always formed in a certain range of sections, it is possible to accurately grasp the image forming performance based on the toner adhesion amount. For example, it is assumed that the test pattern image TP is formed in a section in the range of the in-nip image area ratio that minimizes the primary transfer rate. In this case, the primary transfer rate is specified based on a prior experiment, and a coefficient for correcting the toner adhesion amount of the test toner image (y, cT, mT, bT) after the primary transfer to a value before the primary transfer is obtained. deep. Then, by multiplying the result of detecting the toner adhesion amount of the test toner image after the primary transfer by the above-mentioned coefficient, the toner adhesion amount before the primary transfer is accurately grasped, and the image forming performance of the image forming means is accurately determined. I can grasp it.

[Second Example]
Similarly to the image forming apparatus according to the first embodiment, the image forming apparatus according to the second embodiment also counts the number of segment output pixels in each section of the virtual matrix of the photoconductor. Then, the size of the test toner image is adjusted so that the sum of the number of division output pixels of the division for forming the test toner image and the number of pixels of the test toner image falls within a specific range. For example, a nip in an image area ratio S area ratio constant S ₅ or more, so that a value in the range of area ratio constant S _6, adjusting the size of the test toner images. At this time, if the size of the test toner image is less than the lower limit, as shown in FIG. 10, only one of the non-image output areas at both ends in the main scanning direction is Create a test toner that is larger than the lower limit. In this way, by reducing the number of test toner images in the section from two to one, the total number of pixels is set to a specific range while keeping the size of the test toner image at or above the lower limit.

  Further, when it is necessary to create a test toner image having a size exceeding the upper limit and straddling the non-image output area and the image output area, as shown in FIG. The section for forming the test toner image is shifted from the planned section to the section of the inter-page area. This is because no image is formed in the image output area in the inter-page area, and there is no problem even if the test toner image protrudes into the image output area.

  In such a configuration, the size of the test toner image is adjusted so that the total number of pixels in the section falls within a specific range, thereby achieving an image with an in-nip image area ratio S that achieves a predetermined average primary transfer rate. And primary transfer of the test toner image. As a result, regardless of the size of the image portion in the nip, the image area ratio S in the nip is kept constant and the predetermined primary transfer rate is maintained. It becomes possible to accurately grasp the toner adhesion amount of the test toner image. Therefore, it is possible to suppress the occurrence of poor adjustment of the image forming condition (target toner density) due to the fluctuation of the in-nip image area ratio S.

[Third embodiment]
Similarly to the image forming apparatus according to the first embodiment, the image forming apparatus according to the second embodiment also counts the number of segment output pixels in each section of the virtual matrix of the photoconductor. The four test toner images of the test pattern image TP are formed in a predetermined section with a predetermined size without adjusting the size or shifting the section to be imaged.

When the control unit 150 samples the output voltage from the reflective optical sensor to calculate the toner adhesion amount of the test toner image, the following is performed based on the number of division output pixels of the division where the test toner image is formed. Make a decision. That is, it is determined nip image area ratio S within a predetermined range (e.g., the area ratio constant S ₅ or more, less than the area ratio constant S ₆₎ whether the partition number of output pixels to. If the number of output pixels in the nip is not within the predetermined range, the color (y, c, m, b) corresponding to the test toner image is referred without referring to the sampling data. Cancel the target toner density correction. For example, if the number of output pixels of the section where the y test toner image yT is formed is not a value that makes the image area ratio S in the nip within a predetermined range, the correction of the target toner density for y is stopped.

  In such a configuration, the toner adhesion amount of the test toner image before the primary transfer is accurately determined by referring only to the detection result of the toner adhesion amount for the test toner image primarily transferred at the predetermined in-nip image area ratio S. It becomes possible to grasp. Therefore, it is possible to suppress the occurrence of poor adjustment of the image forming condition (target toner density) due to the fluctuation of the in-nip image area ratio S.

  FIG. 13 is a graph showing the relationship among the primary transfer rate, the image area ratio in the nip, and the charging potential of the photosensitive member. As shown in the figure, even if the image area ratio in the nip is the same, the primary transfer ratio on the high image area ratio side decreases as the charged potential of the photosensitive member decreases. Therefore, the value (reference pixel number range) to be compared with the number of divided output pixels when determining whether or not to correct the target toner density using sampling data is corrected based on the charged potential of the photoconductor. It is desirable to do. For example, when the charged potential of the photosensitive member is 500 [V] or more, a reference pixel number range including the number of segment output pixels corresponding to the in-nip image area ratio S = 80 [%] is used. On the other hand, when the charging potential is less than 500 [V], the number of divided output pixels corresponding to the in-nip image area ratio S = 80 [%] is not included, and the in-nip image area ratio S = 70 [%]. ] Using the reference pixel number range that includes the number of segment output pixels corresponding to.

  As shown in FIG. 1, in the configuration in which the intermediate transfer belt 15 is sequentially passed through the primary transfer nips of y, c, m, and b, the toner transferred onto the belt at the primary transfer nip upstream in the belt moving direction is transferred to the downstream side. May be reversely transferred to the photoreceptor at the primary transfer nip. Since the photoreceptor for b is located on the most downstream side, reverse transfer does not occur on the downstream side for the b toner image. However, the y toner image, c toner image, and m toner image may each cause reverse transfer on the downstream side.

  FIG. 14 is a graph showing the relationship between the reverse transfer rate at the downstream primary transfer nip and the charging potential of the downstream photoconductor (the photoconductor forming the same primary transfer nip). As shown in the figure, the higher the charging potential of the downstream photoconductor, the higher the reverse transfer rate at the downstream primary transfer nip. That is, as the charging potential of the downstream photoconductor increases, the detection result of the toner adhesion amount of the test toner image becomes smaller than the original value (value before primary transfer).

  Further, as the image area ratio in the nip at the downstream primary transfer nip decreases, reverse transfer is more likely to occur. The image area ratio in the nip is the image of the image portion in the primary transfer nip in the image on the downstream photoconductor when the test toner image primarily transferred onto the intermediate transfer belt 15 enters the downstream primary transfer nip. Area ratio. Hereinafter, the image area ratio is referred to as the downstream synchronous nip area ratio. For this reason, it is desirable to correct the reference pixel number range not only based on the charging potential of the photoconductor that forms the test toner image but also based on the area ratio in the downstream synchronization nip and the charging potential of the downstream photoconductor. For example, the total area ratio in the downstream synchronization nip (for example, when there are two downstream colors, the total of the two colors) is 75% or more, and all the charging potentials of all the downstream photoconductors are 700 [V]. ], The target toner density is not corrected. Further, if the total area ratio in the downstream synchronization nip is 60% or more and the charging potentials of all the downstream photoconductors are 700V or more, the target toner density is not corrected. . What is necessary is just to set according to the sum total of the preset reverse transfer rate according to the charging potential of a downstream photoconductor. Further, a method of correcting the reference pixel number range in accordance with the charging potential of the downstream photoconductor may be employed. Correction may be performed using a data table indicating the relationship among the reference pixel number range, the area ratio in the downstream synchronization nip, the charging potential of the photosensitive member, and the charging potential of the downstream photosensitive member.

  Therefore, the control unit 150 corrects the reference pixel number range based on the charging potential of the photoconductor, the charging potential of the downstream photoconductor, and the area ratio in the downstream synchronization nip, and corrects the reference pixel number range and the section after correction. Whether or not to correct the target toner density is determined based on the total number of pixels.

  If one of the four colors y, c, m, and b has failed to correct the target toner density, the target image density cannot be obtained for that color. In this case, it is desirable to correct the target toner density for that color at the earliest possible timing. Therefore, when there is even one color whose target toner density cannot be corrected, the control unit 150 advances the execution timing of the next target toner density correction process earlier than the normal timing. For example, when the target toner density correction process is performed every 10 sheets, the next execution timing is after 10 sheets are printed, but it is advanced after one sheet is printed.

  FIG. 15 is a flowchart showing a processing flow of the target toner density correction process performed by the control unit 150. When the execution timing of the target toner density correction process arrives (Y in S1), the control unit 150 creates a test pattern image TP in parallel with creating an image based on the image information (S2). Then, after correcting the reference pixel number range based on the charging potential of the photosensitive member, the charging potential of the downstream photosensitive member, and the area ratio in the downstream synchronization nip (S3), the pixels in the section where the test toner image is formed The total number is calculated (S4). Next, it is determined whether the total number of pixels is within the reference pixel number range, that is, whether the sampling data of the output voltage of the reflective optical sensor can be referred to (S5). If the reference is possible (Y in S5), after calculating the toner adhesion amount based on the sampling data (S6), the target toner density is corrected based on the calculation result (S7), and all It is determined whether or not the color has been examined (S8). If the reference is not possible (N in S5), the determination in S8 is performed without performing S6 or S7.

  If all the colors have not been examined (N in S8), the processing flow is looped to S3, whether or not sampling data can be referred to for unexamined colors, and the target toner density is set as necessary. Or correct it. On the other hand, if all the colors have been examined (Y in S8), it is determined whether there is a color whose target toner density could not be corrected (S9). If there is a color that could not be corrected (Y in S9), the execution timing of the next target toner density correction processing is corrected to a timing earlier than normal (S10), and then the series of processing flow ends. On the other hand, if there is no color that could not be corrected (N in S9), the processing flow is immediately terminated.

  The application of the present invention is not limited to the image forming apparatus according to the embodiment, and various modifications and changes are possible. For example, as an image forming apparatus to which the present invention can be applied, a copying machine, a facsimile machine, a multifunction machine, etc. can be exemplified instead of a printer. The present invention can also be applied to a monochrome image forming apparatus that can form only a monochrome image, not an image forming apparatus that forms a color image. In addition, the present invention can be applied to an image forming apparatus configured to form an image on both sides as necessary, instead of forming an image on only one side of a recording sheet. Examples of the recording sheet include plain paper, OHP sheet, card, postcard, cardboard, envelope, and the like.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
[Aspect A]
An image information acquisition unit (for example, an image information input unit 151) that acquires image information, an image output region where an image based on the image information is formed, and a non-image output region where the image is not formed are the own surface movement directions. An image carrier (eg, photoconductors 11y, 11c, 11m, and 11b) provided so as to be arranged in a direction orthogonal to the image, and an image forming unit (image forming unit) that forms a toner image on the moving surface of the image carrier. 10y, 10c, 10m, 10b and a latent image writing device 13), transfer means (for example, transfer unit 50) for transferring the toner image on the image carrier onto the surface of the transfer member, A test in which an image is formed on a non-image output area existing at an end of the surface in a direction orthogonal to the surface moving direction, and then transferred to the transfer body (for example, the intermediate transfer belt 15) by the transfer unit. An adhesion amount detection means (for example, the optical sensor unit 30) for detecting the toner adhesion amount of the toner image, and the test toner image is formed in the non-image output area, and the toner adhesion amount is detected by the adhesion amount detection means. In an image forming apparatus including a control unit (for example, the control unit 150) that performs an image forming condition adjustment process for adjusting an image forming condition of the image forming unit based on a result, an image based on the image information is displayed in the image output area. In parallel with the image forming process for forming the image, the image forming condition adjusting process is performed, and the test toner image formed in the non-image output area is formed in the image output area in the orthogonal direction. The control means is configured to form the images side by side.

  In such a configuration, the test toner image is moved on the surface of the image carrier relative to the image formed in the image output area of the image carrier out of the entire area of the non-image output area of the image carrier in the image carrier surface movement direction. An image is formed in a region aligned in a direction orthogonal to the direction. In the image carrier surface movement direction, an area where an image is formed is not an inter-page area but an area corresponding to a page. In other words, in the present invention, since the test toner image is not formed in the inter-page region, it is not necessary to expand the inter-page region, and this is caused by expanding the inter-page region for image forming condition adjustment processing. The occurrence of device downtime can be suppressed.

[Aspect B]
Aspect B is the aspect A, in which the image output condition and the non-image output area are integrally partitioned into a plurality along the surface movement direction in the image formation condition adjustment process, The control means is configured to identify the non-image output area in a section in which the size of the image portion to be imaged in the image output area is within a predetermined range, and to create the test toner image in the non-image output area. It is characterized by comprising. In such a configuration, a test toner image is formed in a section where the transfer rate is within a predetermined range of the entire area in the moving direction of the surface of the image carrier, and the toner adhesion amount before the transfer of the test toner image is accurately determined. To grasp. As a result, it is possible to suppress the occurrence of poor adjustment of the image forming conditions due to the primary transfer rate of the test toner image varying depending on the image area rate in the nip.

[Aspect C]
In the aspect A, the image output condition and the non-image output area are integrally divided into a plurality along the surface movement direction in the image formation condition adjustment process, and the test is performed among the sections. The control means is configured to vary the size of the test toner image formed in the section in the orthogonal direction according to the size of the image portion of the image output area in the section where the toner image is formed. It is characterized by comprising. In such a configuration, the size of the test toner image is adjusted so that the total number of pixels in the section falls within a specific range, so that the image and the test toner image have an image area ratio in the nip that achieves a predetermined transfer rate. Transcript. As a result, regardless of the size of the image portion in the nip, the test area before the primary transfer is based on the detection result of the toner adhesion amount by keeping the image area ratio in the nip constant and maintaining the predetermined transfer rate. It is possible to accurately grasp the toner adhesion amount of the image. Therefore, it is possible to suppress the occurrence of poor adjustment of the image forming condition due to the fluctuation of the image area ratio in the nip.

[Aspect D]
Aspect D is the aspect A, in which the image output area and the non-image output area are integrally divided into a plurality along the surface movement direction in the image formation condition adjustment process, Based on the size of the image portion of the image output area in the section where the test toner image is formed, the adjustment of the image forming condition for the detection result of the toner adhesion amount of the test toner image formed in the section The control means is configured to determine whether or not to make a reference. In such a configuration, the toner adhesion amount of the test toner image before transfer is accurately grasped by referring only to the detection result of the toner adhesion amount for the test toner image transferred at a predetermined in-nip image area ratio. Thereby, it is possible to suppress the occurrence of poor adjustment of the image forming condition due to the fluctuation of the image area ratio in the nip.

[Aspect E]
Aspect E is the step of adjusting the size of the test toner image in the image formation condition adjustment processing in aspect C, and matching the image portion and the test toner image in the section where the test toner image is formed. The control means is configured so that the image area ratio is set to the size within a specific range. In such a configuration, by adjusting the size of the test toner image, the area ratio in the nip of the section where the test toner image is formed can be kept within a specific range.

[Aspect F]
Aspect F is the aspect E of the aspect E, in which when the size of the test toner image is varied in the image formation condition adjustment process, the image area where the test toner image is formed and the image area of the test toner image are combined. If it is necessary to create the test toner image having a size straddling the non-image output area and the image output area in order to keep the rate within the specific range, the test toner image having the size is used. Instead of the planned section, the control means is configured to form an image in a section that exists in the inter-page area in the moving direction of the image carrier. In such a configuration, even if the test toner image becomes large enough to straddle the non-image output area and the image output area, the test toner image can be formed without affecting the output image.

[Aspect G]
Aspect G is the step of determining whether or not to refer to the detection result of the toner adhesion amount of the test toner image in the image formation condition adjustment processing in aspect D, in which the test toner image is formed. When the size of the image portion is not within a predetermined range and the absolute value of the charging potential at the background portion of the image carrier is not within the predetermined range, the control is performed so as not to refer to the detection result. It is characterized by comprising means. In such a configuration, even if the charging potential of the background portion of the image carrier fluctuates, it is possible to continue to refer only to the detection result of the toner adhesion amount that accurately reflects the image forming performance of the image forming means.

[Aspect H]
Aspect H is the aspect D or G in which a plurality of the image carriers are provided, and among these image carriers, the upstream disposed at a position upstream of the other image carriers in the surface movement direction of the transfer body. For the test toner image formed on the side image carrier, the test toner image in the transfer step among the plurality of sections in the downstream image carrier disposed downstream of the upstream image carrier. The control means determines whether or not to refer to the detection result of the toner adhesion amount using the result of grasping the size of the image portion formed in the section synchronized with the image based on the image information. It is characterized by comprising. In such a configuration, it is possible to continue to refer only to the detection result of the toner adhesion amount that accurately reflects the image forming performance of the image forming unit, regardless of the reverse transfer rate in the downstream transfer process.

[Aspect I]
Aspect I is a process of determining whether or not to refer to the detection result of the toner adhesion amount of the test toner image in the image forming condition adjustment process in the aspect D, G, or H, and does not refer to the detection result. In this case, the control means is configured so that the timing until the next execution of the imaging condition adjustment processing is made earlier than the normal timing. With such a configuration, it is possible to suppress long-term continuation of image density defects due to continued inability to adjust image forming conditions.

[Aspect J]
Aspect J is an image information acquisition unit that acquires image information, an image carrier, an image formation unit that forms a toner image on a moving surface of the image carrier, and a toner image on the image carrier. A transfer means for transferring to the surface of the body; and after the image forming means forms an image on a non-image output region existing at an end portion in a direction perpendicular to the surface movement direction on the surface of the image carrier, the transfer means An adhesion amount detection unit that detects the toner adhesion amount of the test toner image transferred to the transfer body, and the test toner image is formed in the non-image output area and the toner adhesion amount is detected by the adhesion amount detection unit. A control apparatus mounted on an image forming apparatus, comprising: a control apparatus that performs an image forming condition adjustment process that adjusts an image forming condition of the image forming unit based on a result of the determination. The control means; Flip is characterized in city you configure.

10y, 11c, 11m, 11b: Image forming unit (part of image forming means)
11y, 11c, 11m, 11b: photoconductor (image carrier)
13: Latent image writing device (part of image forming means)
15: Intermediate transfer belt (transfer body)
30: Optical sensor unit (attachment amount detection means)
50: Transfer unit (transfer means)
150: Control unit (control means)
151: Image information input unit (image information acquisition means)

Japanese Patent No. 4766609

Claims (10)

Image information acquisition means for acquiring image information, an image output area in which an image based on the image information is formed, and a non-image output area in which the image is not formed are arranged in a direction orthogonal to the surface movement direction An image carrier provided; an image forming unit that forms a toner image on a moving surface of the image carrier; a transfer unit that transfers a toner image on the image carrier to a surface of a transfer member; After the image is formed in the image output area, an adhesion amount detection means for detecting the toner adhesion amount of the test toner image transferred to the transfer body by the transfer means, and the test toner image is formed in the non-image output area An image forming apparatus comprising: a control unit that performs an image forming condition adjustment process that adjusts an image forming condition of the image forming unit based on a result of detecting the toner attached amount by the attached amount detecting unit;
In parallel with the image forming process for forming an image based on the image information in the image output area, the image forming condition adjustment process is performed, and the test toner image formed in the non-image output area is formed in the orthogonal direction. The image forming apparatus according to claim 1, wherein the control unit is configured to form an image side by side with an image to be formed in the image output area. The image forming apparatus according to claim 1.
In the image forming condition adjustment process, the image output area and the non-image output area are integrally divided into a plurality along the surface movement direction, and an image is formed in the image output area among these sections. An image characterized in that the control means is configured to identify the non-image output area in a section where the size of the image portion is within a predetermined range and to form the test toner image in the non-image output area. Forming equipment. The image forming apparatus according to claim 1.
In the image forming condition adjusting process, the image output area and the non-image output area are integrally divided into a plurality along the surface movement direction, and the test toner image is formed in these areas. The control means is configured to vary the size of the test toner image formed in the section in the orthogonal direction according to the size of the image portion of the image output area in the section. Image forming apparatus. The image forming apparatus according to claim 1.
In the image forming condition adjusting process, the image output area and the non-image output area are integrally divided into a plurality along the surface movement direction, and the test toner image is formed in these areas. Whether to refer to the detection result of the toner adhesion amount of the test toner image formed in the section based on the size of the image portion of the image output area in the section for the adjustment of the image forming condition An image forming apparatus characterized in that the control means is configured to determine the above. The image forming apparatus according to claim 3.
When changing the size of the test toner image in the image forming condition adjustment processing, the image area ratio of the image portion and the test toner image in the section where the test toner image is formed is within a specific range. An image forming apparatus characterized in that the control means is configured so as to have a size that can be accommodated in a housing. The image forming apparatus according to claim 5.
When changing the size of the test toner image in the image forming condition adjustment process, the image area ratio including the image portion where the test toner image is formed and the test toner image is within the specific range. Therefore, when it is necessary to create the test toner image having a size straddling the non-image output region and the image output region, the test toner image having the size is divided into the predetermined section. Instead, the image forming apparatus is characterized in that the control means is configured to form an image in a section existing in the inter-page area in the moving direction of the image carrier. The image forming apparatus according to claim 4.
When determining whether or not to refer to the detection result of the toner adhesion amount of the test toner image in the image forming condition adjustment processing, the size of the image portion of the section where the test toner image is formed is predetermined. And the control means is configured to determine not to refer to the detection result when the absolute value of the charging potential at the background portion of the image carrier is not within a predetermined range. An image forming apparatus. The image forming apparatus according to claim 4 or 7,
A plurality of the image carriers are provided, and among the image carriers, the image is formed on the upstream image carrier disposed at a position upstream of the other image carriers in the surface movement direction of the transfer member. Regarding the test toner image, an image formed in a section synchronized with the test toner image in the transfer step among the plurality of sections in the downstream image carrier disposed on the downstream side of the upstream image carrier. The control unit is configured to determine whether or not to refer to the detection result of the toner adhesion amount using a result obtained by grasping the size of the part based on the image information. apparatus. The image forming apparatus according to claim 4, 7 or 8.
When determining whether or not to refer to the detection result of the toner adhesion amount of the test toner image in the image formation condition adjustment process, if the detection result is not referred to, the next image formation condition is determined. An image forming apparatus characterized in that the control means is configured so that the timing until the adjustment processing is performed is earlier than the regular timing. Image information acquisition means for acquiring image information, an image carrier, an image forming means for forming a toner image on the moving surface of the image carrier, and a toner image on the image carrier on the surface of the transfer body The transfer means for transferring, and the image forming means forms an image on a non-image output region existing at an end portion of the surface of the image carrier perpendicular to the surface moving direction, and then the transfer means applies the image to the transfer body. Based on the result of detecting the toner adhesion amount of the transferred test toner image, and forming the test toner image in the non-image output area and detecting the toner adhesion amount by the adhesion amount detection means. In the control device mounted on the image forming apparatus, comprising a control device that performs image forming condition adjustment processing for adjusting the image forming condition of the image forming means,
An image forming apparatus having the same configuration as that of the control unit of the image forming apparatus according to claim 1.

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