JP6060745B2 - Image forming apparatus and program - Google Patents

Description

  The present invention relates to an image forming apparatus and a program.

  2. Description of the Related Art Conventionally, there has been proposed a technique related to correction processing for correcting density unevenness of a printed image in an image forming apparatus such as a printer or a copying machine.

  Patent Document 1 discloses an image density correction method in an image forming apparatus that can reduce density unevenness in the main scanning direction. In this method, the same image transferred to a plurality of positions in the main scanning direction on the transfer object is read, the density of the image at each position is detected, the difference in each density is calculated, and the calculated density difference is a predetermined density. The image density is corrected by adjusting the exposure output in the main scanning direction so as to be within the allowable range.

  Japanese Patent Laid-Open No. 2004-228688 includes a relationship obtained in advance between an image feature amount of each of a plurality of multiple color images and an image feature amount of a single color image corresponding to the image feature amount, and an image feature amount distribution of the multiple color image. A configuration is disclosed in which an image feature amount distribution of a single color image in a multi-color image is calculated, and an exposure condition corresponding to the single color image on the photoconductor is determined based on the calculated image feature amount distribution. .

  In Patent Document 3, an image pattern of a density pattern stored in a memory is formed on a transfer sheet, and the image density at the image center position of the image pattern read by setting the transfer sheet on a document reading unit is used as a reference density. A configuration is disclosed in which the reference density is compared with the image density at an arbitrary position in the main scanning direction of the read image pattern, and the write light amount is corrected so that the image density at a position different from the reference density is the same as the reference density. Has been.

JP 2001-66835 A JP 2004-138609 A JP 2002-49189 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus and a program capable of improving image quality by correcting density unevenness generated in the plane of a printed image with high accuracy.

  An image forming apparatus according to a first aspect of the present invention includes an image creating unit that creates a plurality of images with different exposure amounts on an intermediate transfer member, and a density calculation that calculates the density of the plurality of images created on the intermediate transfer member. And a sensitivity calculating means for calculating an exposure sensitivity represented by a change amount of density with respect to a change amount of exposure amount based on the exposure amount and the calculated density in each of the plurality of images, and the calculation Adjusting means for adjusting an exposure amount for the print image based on the exposure sensitivity.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, a density measuring unit that measures the density of a plurality of images formed on the intermediate transfer member, and a measured value of the density measuring unit. And a storage unit that stores a preset concentration corresponding to the measurement value, and the concentration calculation unit acquires the concentration corresponding to the measurement value of the concentration measurement unit from the storage unit .

  An image forming apparatus according to a third aspect of the present invention is the image processing apparatus according to the first aspect, further comprising image capturing means for capturing a test image printed on a recording medium as image data into the image forming apparatus. In parallel with the processing, processing for calculating the exposure sensitivity is performed.

  According to a fourth aspect of the present invention, in the configuration according to the third aspect, the image forming apparatus further includes a density difference calculating unit that calculates a density difference in the captured image data.

  According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the image forming apparatus further includes a correction value calculating unit that calculates an exposure correction value for adjusting the exposure amount, and the correction value calculating unit includes: The exposure correction value is calculated so as to reduce the density difference.

  An image forming apparatus according to a sixth aspect of the present invention is the image forming apparatus according to the first aspect, wherein when the image densities of the plurality of images are different from each other, based on the exposure sensitivity in the image having the highest exposure sensitivity, The exposure sensitivity in the image is calculated.

  According to a seventh aspect of the present invention, in the configuration according to the first aspect, the densities of the plurality of images created on the intermediate transfer member calculated by the density calculating unit are set in advance. It further comprises density determination means for determining whether or not it is within a reference range, and when the density is not within the reference range, processing by the image creation means and processing by the density calculation means are performed again.

  In the image forming apparatus according to claim 8 of the present invention, in the configuration according to claim 7, when the density is not within the reference range, the image creation is repeated until the density falls within the reference range. The processing by the means and the processing by the density calculation means are performed.

  According to a ninth aspect of the present invention, in the configuration according to the seventh or eighth aspect, when the density is within the reference range, the processing by the sensitivity calculating unit is performed.

  According to a tenth aspect of the present invention, in the configuration according to the first aspect, the densities of the plurality of images created on the intermediate transfer member, which are calculated by the density calculating unit, are preset. A density determination unit that determines whether or not it is within a reference range; and a frequency measurement unit that measures the number of times the processing by the image creation unit and the processing by the density calculation unit are performed, wherein the density is the reference If it is not within the range, the process by the image creating unit and the process by the density calculating unit are repeated until the number reaches a preset reference number.

  An image forming apparatus according to an eleventh aspect of the present invention is the image forming apparatus according to the tenth aspect, wherein the adjusting unit is configured such that the density is not within the reference range and the number of times reaches the reference number of times. Then, the exposure amount for the print image is adjusted based on the exposure sensitivity calculated in the exposure amount adjustment process performed last time.

  An image forming apparatus according to a twelfth aspect of the present invention is the image forming apparatus according to the tenth aspect, wherein the adjusting unit is configured such that the density is not within the reference range and the number of times reaches the reference number. The exposure amount for the print image is adjusted based on the initial exposure sensitivity.

  An image forming apparatus according to a thirteenth aspect of the present invention is the image forming apparatus according to the eleventh aspect, wherein the storage unit stores the exposure sensitivity calculated in the exposure amount adjustment process performed in the past, and the density is within the reference range. And a sensitivity acquisition means for acquiring the exposure sensitivity calculated in the previous exposure amount adjustment process from the storage unit when the number of times reaches the reference number. Yes.

  In the image forming apparatus according to claim 14 of the present invention, in the configuration according to claim 7 or 10, when the density is not within the reference range, the image forming apparatus is connected to a terminal that manages the image forming apparatus. Announce the abnormality.

  According to a fifteenth aspect of the present invention, there is provided a computer-readable recording medium for generating a plurality of images having different exposure amounts on an intermediate transfer member, and a density calculation for calculating a density of the plurality of images generated on the intermediate transfer member. Means for calculating an exposure sensitivity represented by a change amount of density with respect to a change amount of exposure amount based on the exposure amount and the calculated density in each of the plurality of images; and the calculation Based on the exposed exposure sensitivity, it functions as an adjusting means for adjusting the exposure amount for the print image.

  According to the configuration of the first and fifteenth aspects of the present invention, the density unevenness generated in the plane of the printed image is corrected with high accuracy, and the image quality can be improved.

  According to the configuration of the second aspect of the present invention, the image density is easily calculated.

  According to the configuration of the third aspect of the present invention, the time for density unevenness correction processing is shortened by the parallel processing.

  According to the configuration of the fourth aspect of the present invention, density unevenness occurring in the printed image is detected.

  According to the configuration of the fifth aspect of the present invention, the density difference is reduced, so that density unevenness is eliminated.

  According to the configuration of the sixth aspect of the present invention, the control time on the intermediate transfer member is shortened.

  According to the configurations of the seventh to ninth aspects of the present invention, abnormality occurring in the intermediate transfer member or the like is detected, and more accurate exposure amount control (adjustment) is performed.

  According to the configurations of claims 10 to 13 of the present invention, an abnormality occurring in the intermediate transfer member or the like is detected, more accurate unevenness correction is performed, and the number of times the determination process is repeated is limited, and unevenness correction processing is performed. Time is shortened.

  According to the configuration of the fourteenth aspect of the present invention, the internal abnormality of the image forming apparatus can be quickly dealt with (repair, replacement, etc.).

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an exemplary embodiment. It is a block diagram which shows the structure of the nonuniformity correction apparatus which concerns on this Embodiment. 3 is a flowchart illustrating unevenness correction processing according to the first exemplary embodiment. 1 is a block diagram illustrating configurations of a control device and an exposure sensitivity calculation device according to Embodiment 1. FIG. FIG. 3 is a diagram showing a state of patches created on an intermediate transfer member. It is a graph which shows the relationship between the parameter value of an ADC sensor, and the density | concentration of a patch. It is the graph which plotted the reading and density | concentration of an ADC sensor. It is a graph which shows the relationship between measured density | concentration and exposure amount. 10 is a flowchart illustrating unevenness correction processing according to the second embodiment. It is a block diagram which shows the structure of the control apparatus and exposure sensitivity calculating apparatus which concern on Example 2. FIG. It is a graph which shows the relationship between the parameter value of an ADC sensor, and the density | concentration of a patch. 10 is a flowchart illustrating unevenness correction processing according to the third embodiment. It is a block diagram which shows the structure of the control apparatus which concerns on Example 3, and an exposure sensitivity calculating apparatus. It is a graph which shows the relationship between Cin and exposure sensitivity. It is a figure which shows the relationship between a test chart and a scanning direction. 10 is a flowchart illustrating a modification example of the unevenness correction process according to the second embodiment. 12 is a flowchart illustrating a modification example of the unevenness correction process according to the third embodiment.

  An embodiment of the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, the image forming apparatus 10 according to the present embodiment includes a main unit 200, a discharge unit 202 positioned on one side of the main unit 200, and a plurality of supply units positioned on the other side of the main unit 200. A paper feed unit 204 having a paper tray 24 and an image input device (image capturing means, scanner) 28 located on the upper surface of the paper feed unit 204 are provided. A toner supply device 30 that supplies each color material (YMCK) is provided on the upper surface of the main unit 200.

  In the main unit 200, transfer engines 12 for each color of Y (yellow), M (magenta), C (cyan), and K (black), which are arranged side by side in order in one direction (hereinafter referred to as necessary). Y, M, C, and K are attached to the end of each, and Y, M, C, and K are also attached to the other members in the same manner. The transfer engines 12Y to 12K further include an exposure device 14 including a laser light source (not shown), a polygon mirror, and other mirrors for recording a latent image on the photosensitive drum 16 based on the on / off binarized toner signal. The exposure device 14 irradiates the photosensitive drum 16 with laser light based on the image output data, transfers the image to the intermediate transfer member (belt) 20 via the primary transfer device 17 provided with the primary transfer roll, and the intermediate transfer member 20. The transfer image portion and the recording paper (recording medium) are sandwiched by the transfer device 25 to output an image to the recording paper.

  A photosensitive drum 16 is disposed at the center of each engine 12. A primary charger and a developing unit 18 are provided around the photosensitive drum 16.

  The intermediate transfer body 20 is wound around a plurality of belt conveyance rolls and conveyed. The transfer device 25 is disposed at a predetermined position in the transport path. A fixing device 26 is disposed on the downstream side in the transport direction of the sheet onto which the image has been transferred. In addition to the path leading to the discharge unit 202, the sheet transport path after the fixing device 26 is returned to the paper feeding unit 204, switched back by the paper feeding unit 204, and returned to the transfer device 25. Is provided with a reverse transfer path for transferring the image.

  An ADC sensor 27 (density measuring means) that measures the density of the image created on the intermediate transfer body 20 by the image creating unit (image creating means) is provided on the upstream side in the transport direction with respect to the transfer device 25. In particular, the ADC sensor 27 measures the density of a density detection image (hereinafter referred to as a patch) created on the intermediate transfer body 20. When the ADC sensor 27 measures the patch, the ADC sensor 27 supplies the measurement result (sensor reading value) to the exposure sensitivity calculation device 29. For example, the ADC sensor 27 has a sensor reading value in a range of 0 to 1024 (corresponding to 0 V to 24 V), and supplies the sensor reading value as a measurement result to the exposure sensitivity calculation device 29.

  FIG. 2 shows a control system of the image forming apparatus 10 according to the present embodiment. As shown in FIG. 2, the present control system includes a control device 32 (adjustment means) that controls the exposure devices 14Y to 14K. The control device 32 controls (adjusts) the exposure amount by outputting an exposure correction value to the exposure devices 14Y to 14K. The control device 32 is connected to the scanner 28 and an exposure sensitivity calculation device 29 (exposure sensitivity calculation means).

  Next, a general configuration of the image forming process will be described. In the exposure device 14, the Y (yellow) laser light source is first driven by a Y color on / off binarized toner signal, thereby converting the Y color on / off binarized signal into an optical signal. Then, the converted laser beam is irradiated toward the photosensitive drum 16Y. Thus, the laser beam scans the photosensitive drum 16Y charged by the primary charger, thereby forming an electrostatic latent image on the photosensitive drum 16.

  The electrostatic latent image is formed as a toner image by the developing unit 18 to which Y toner is supplied from the toner supply device 30. The photosensitive drum 16 and the primary transfer roll make a pair, and the intermediate transfer body 20 is driven, whereby the toner image is transferred to the intermediate transfer body 20. After the transfer, excess toner is removed from the photosensitive drum 16 by the cleaner.

  Similarly, the primary charger based on the corresponding on / off binarized toner signals of M, C, and K, which are sequentially obtained at regular intervals with respect to the Y on / off binarized toner signal. By scanning the photosensitive drums 16M, 16C, and 16K charged by, electrostatic latent images are sequentially formed on the photosensitive drums 16M, 16C, and 16K, respectively.

  Each electrostatic latent image is sequentially converted into a toner image by the developing device 18 to which each color toner is supplied from the toner supply device 30, and each toner image is sequentially transferred onto the intermediate transfer body 20 by the primary transfer roll. After the transfer, excess toner is removed from the photosensitive drum 16 by the cleaner.

  After the transfer, the portion of the intermediate transfer body 20 where the image is transferred is conveyed to the transfer device 25. The recording paper is conveyed from the paper feed tray 24 to the transfer device 25, and the transfer device 25 conveys the transferred image portion on the intermediate transfer body 20 and the recording paper to the downstream side, thereby transferring the image to the recording paper. Output an image.

  The recording paper on which the toner images of each color of Y, M, C, and K are sequentially transferred in this manner is peeled off from the intermediate transfer body 20, and the toner image is thermally fixed by the fixing device 26, and the toner image is applied to the recording paper. After fixing, it is discharged to the discharge unit 202. In certain cases, an image is also output on the reverse side of the paper as described above via a path for switching back the paper.

  Next, correction processing when density unevenness occurs in the surface of a print image will be described.

[Example 1]
Density unevenness correction (hereinafter referred to as unevenness correction) processing according to Example 1 of the present embodiment will be described with reference to FIGS. FIG. 3 is a flowchart illustrating unevenness correction processing according to the first embodiment, and FIG. 4 is a functional block diagram illustrating schematic configurations of the control device 32 and the exposure sensitivity calculation device 29 according to the first embodiment.

  As shown in FIG. 4, the control device 32 (adjustment unit) includes a density difference calculation unit 321 (density difference calculation unit), a correction value calculation unit 322, and a correction value output unit 323. The exposure sensitivity calculation device 29 includes a density calculation unit 291 (density calculation unit), a sensitivity calculation unit 292 (sensitivity calculation unit), and a storage unit 293.

  In step 11 (hereinafter referred to as S11), each engine 12Y-12C is controlled to output a test chart (recording medium) (see FIG. 15) on which a test image is printed. The test image may be a single color image (single color patch) of each color material, or may be an image of multiple colors of CM, MY, YC, and YMC (multiple color patch).

  Next, the test chart is scanned by the scanner 28 (take-in means) (S12). Image data scanned by the scanner 28 is taken into the control device 32. When acquiring the image data from the scanner 28, the density difference calculating unit 321 of the control device 32 calculates the density difference in the image of the image data (S13). For example, the density difference at both end points in the halftone image is calculated. For example, when the density at one end (point A) is 1.00 (100%) and the density at the other end (point B) is 1.20, 0.20 is calculated as the density difference. The density difference calculation unit 321 outputs the calculated density difference to the correction value calculation unit 322. That is, the density difference calculation unit 321 detects density unevenness that occurs in the printed image.

  In parallel with the scanning process, a plurality of patches set at different exposure amounts by the exposure device 14 are created on the intermediate transfer body 20 (S14), and the patches are measured by the ADC sensor 27 (S15). The sensor reading value (actual measurement value) measured by the ADC sensor 27 is supplied to the density calculation unit 291 of the exposure sensitivity calculation device 29. Further, in parallel with the scanning process, the density calculation unit 291 calculates the density (actual density) based on the sensor reading value (actual measurement value) acquired from the ADC sensor 27 (S16), and the sensitivity calculation unit 292 The exposure sensitivity is calculated based on the exposure amount and the calculated actual density (S17). The exposure sensitivity represents the density change amount per 1% of the exposure amount.

  Here, the calculation method of exposure sensitivity will be described below with a specific example.

  FIG. 5 shows a patch P0 with a reference exposure amount (100%), a patch P1 (exposure amount 110%) obtained by increasing the exposure amount by + 10% with respect to the reference exposure amount, and an exposure amount with respect to the reference exposure amount − A state in which a patch P2 (exposure amount 90%) reduced by 10% is formed on the intermediate transfer member 20 is shown. FIG. 6 is a graph showing the relationship between the sensor reading value (parameter value) of the ADC sensor 27 and the patch density. The relationship between the sensor reading value (parameter value) and the concentration (predicted concentration) of the ADC sensor 27 shown in FIG. 6 is preset and stored in the storage unit 293. In the unevenness correction according to the present embodiment, the exposure sensitivity calculation device 29 sets a preset value corresponding to the actual measurement value from the sensor reading value (actual measurement value) of the ADC sensor 27 with respect to the patch created on the intermediate transfer body 20. The concentration (measured concentration) is calculated. FIG. 7 is a graph plotting sensor readings (actually measured values) of the ADC sensor 27 and preset concentrations (actually measured concentrations) corresponding thereto.

  In the above example, when the sensor reading value of the ADC sensor 27 with respect to the patch P0 is 550, the density of the patch P0 is 1.20, and when the sensor reading value of the ADC sensor 27 with respect to the patch P1 is 525, the patch P1. The density of the patch P2 is 1.12 when the sensor reading value of the ADC sensor 27 for the patch P2 is 595.

  The exposure sensitivity calculation device 29 calculates the exposure sensitivity based on the measured density. FIG. 8 is a graph showing the relationship between the actually measured density and the exposure amount. Here, the density of the patch P0 with the reference exposure amount (100%) is 1.20, the density of the patch P1 with the exposure amount (110%) is 1.28, and the density of the patch P2 with the exposure amount (90%). The concentration is 1.12. According to the example of this graph, when the exposure amount is increased by 1%, the density is increased by 0.008 (density change amount), and when the exposure amount is decreased by 1%, the density is 0.008 (density change amount). It can be seen that it decreases only. A conversion formula X representing this relationship corresponds to exposure sensitivity.

  The sensitivity calculation unit 292 outputs the calculated exposure sensitivity, that is, the conversion equation to the control device 32 (S17).

  The correction value calculation unit 322 of the control device 32 is based on the density difference of the image data acquired from the density difference calculation unit 321 and the exposure sensitivity (conversion formula X) acquired from the sensitivity calculation unit 292 of the exposure sensitivity calculation device 29. A correction value (exposure correction value) for correcting the density difference (density unevenness) is calculated (S18). Here, since the density difference is 0.20, −25% is calculated as the exposure correction value from the conversion formula X. The correction value calculation unit 322 does not perform the exposure correction value calculation process when the density difference is within a preset reference range. That is, when the density difference is at a level that is recognized as in-plane unevenness, density unevenness correction processing is performed.

  Finally, the correction value output unit 323 of the control device 32 outputs the calculated exposure correction value to the exposure device 14 (14Y to 14K) (S19), and controls (adjusts) the exposure amount of the exposure devices 14Y to 14K. .

  As described above, in the unevenness correction according to the present embodiment, the patch created on the intermediate transfer body 20 is measured by the ADC sensor 27, and the exposure amount is controlled using the exposure sensitivity calculated based on the measurement result. Yes. That is, the exposure amount is controlled using the exposure sensitivity according to the current use state of the image forming apparatus 10. Therefore, even when the use environment of the image forming apparatus 10 changes, it is possible to perform unevenness correction with high accuracy.

  For example, when the usage environment of the image forming apparatus 10 changes, the sensors of the ADC sensors 27 for the patch P0 (exposure amount 100%), the patch P1 (exposure amount 110%), and the patch P2 (exposure amount 90%). The reading value (actually measured value) and the corresponding concentration (actually measured concentration) are different from the above example (see FIG. 7). Therefore, in this case, a conversion formula Y representing exposure sensitivity different from the conversion formula X is calculated. The control device 32 controls the exposure amount of the exposure device 14 based on the image data scanned by the scanner 28 and the exposure sensitivity (conversion equation Y) calculated by the exposure sensitivity calculation device 29. As described above, even when the use environment of the image forming apparatus 10 changes, the optimum unevenness correction according to the use environment can be performed.

  Further, in the unevenness correction according to the present embodiment, since the unevenness correction is performed by measuring a patch created on the intermediate transfer body 20 by a sensor provided in the image forming apparatus 10, conventional unevenness correction is performed. The number of test charts used for the test can be reduced. Therefore, the unevenness correction process can be simplified. These effects can be similarly obtained in the unevenness correction processing according to Examples 2 and 3 described later.

[Example 2]
The unevenness correction processing according to Example 2 of the present embodiment will be described with reference to FIGS. FIG. 9 is a flowchart illustrating unevenness correction processing according to the second embodiment, and FIG. 10 is a functional block diagram illustrating schematic configurations of the control device 32 and the exposure sensitivity calculation device 29 according to the second embodiment.

  In the unevenness correction according to the second embodiment, the unevenness correction according to the first embodiment further includes a process of determining whether or not the density of the patch created on the intermediate transfer body 20 is normal. As shown in FIG. 10, the exposure sensitivity calculation device 29 further includes a density determination unit 294 (density determination means) that performs the above determination process. According to the unevenness correction according to the second embodiment, for example, when an inappropriate exposure sensitivity is calculated due to an abnormality such as a wave or unevenness in the intermediate transfer body 20, the exposure amount is controlled using the inappropriate exposure sensitivity. Can be prevented.

  Hereinafter, the unevenness correction process according to the second embodiment will be described focusing on differences from the unevenness correction process according to the first embodiment (see FIG. 3).

  First, in S21 of FIG. 9, a test chart (see FIG. 15) on which a patch is printed is output. Next, the test chart is scanned by the scanner 28 (S22). Image data scanned by the scanner 28 is taken into the control device 32. When acquiring the image data from the scanner 28, the density difference calculation unit 321 of the control device 32 calculates the density difference in the image of the image data (S23).

  In parallel with the scanning process, the exposure device 14 creates a plurality of patches set at different exposure amounts on the intermediate transfer body 20 (S24), and measures the patches by the ADC sensor 27 (S25). The sensor reading value (actual measurement value) measured by the ADC sensor 27 is supplied to the density calculation unit 291 of the exposure sensitivity calculation device 29. Further, in parallel with the scanning process, the density calculation unit 291 calculates the density (actual density) based on the sensor reading value (actual value) acquired from the ADC sensor 27 (S26).

  Next, the density determination unit 294 determines whether or not the actually measured density is within a reference range set in advance based on the density (predicted density) for the same exposure amount (S30). FIG. 11 is a graph showing the relationship between the sensor reading value (actually measured value) of the ADC sensor 27 and the actually measured density when an abnormality occurs in the intermediate transfer member 20. As shown in FIG. 11, the actually measured density is 1.10 in the patch P1 (exposure amount 110%), which is much lower than the predicted density 1.27 shown in FIG. In the graph of FIG. 11, in order to compare the patch P1 with the graph of FIG. 6, the actual sensor reading value (actual measurement value = 595) is located at the position of the sensor reading value 525 of the exposure amount 110% (+ 10%). The density (measured density) of 1.10 corresponding to is plotted.

  If the reference range is, for example, ± 5% of the predicted density, the measured density 1.10 exceeds the reference range (1.21 to 1.33) in the example of FIG. In this case, the process returns from S30 (NO) in FIG. 9 to S24, and again a patch creation process (S24) on the intermediate transfer member 20, a patch measurement process (S25) by the ADC sensor 27, and an actual density calculation process. (S26) is performed. As described above, in the unevenness correction process according to the second embodiment, the processes in S24 to S26 are repeated until the actually measured density is within the reference range.

  The determination process of the density determination unit 294 is not limited to the above process. For example, the reference range is set to the actually measured density calculated in the previous unevenness correction process (exposure amount adjustment process). A configuration may be adopted in which it is determined whether or not the actually measured concentration matches the previous actually measured concentration or whether it is within ± 5% of the previous actually measured concentration.

  If the measured density is within the reference range in S30 (YES in S30), the process proceeds to S27, and the sensitivity calculation unit 292 performs exposure sensitivity based on the exposure amount of the patch and the calculated measured density. And the calculated exposure sensitivity is output to the control device 32 (S27). The subsequent processing is the same as the unevenness correction processing according to the first embodiment (see FIG. 3).

  According to the unevenness correction process according to the second embodiment, it is possible to detect an abnormality occurring in the intermediate transfer body 20 and the like, and thus it is possible to control (adjust) the exposure amount more accurately.

[Example 3]
The unevenness correction process according to Example 3 of the present embodiment will be described with reference to FIGS. FIG. 12 is a flowchart illustrating unevenness correction processing according to the third embodiment. FIG. 13 is a functional block diagram illustrating schematic configurations of the control device 32 and the exposure sensitivity calculation device 29 according to the third embodiment.

  In the unevenness correction according to the third embodiment, in the unevenness correction according to the second embodiment (see FIG. 9), when the actually measured density exceeds the reference range (NO in S30), the intermediate transfer member 20 is corrected. A process according to the number of repetitions of the patch creation process (S24), the patch measurement process (S25) by the ADC sensor 27, and the actual density calculation process (S26) is performed. The exposure sensitivity calculation device 29 includes a frequency measurement unit 295 (frequency measurement unit) that measures the number of processing times, a frequency comparison determination unit 296 (frequency determination unit) that compares the processing frequency and a reference frequency, and past unevenness correction. A storage unit 293 that stores the exposure sensitivity calculated in the processing, and a sensitivity acquisition unit 297 (sensitivity acquisition unit) that acquires the exposure sensitivity stored in the storage unit 293 are provided. The storage unit 293 also stores the relationship between the sensor reading value (parameter value) of the ADC sensor 27 and the concentration described above.

  Referring to FIG. 12, when the measured density exceeds the reference range in S40 (NO in S40), the number comparison determination unit 296 performs a patch creation process (S34) on the intermediate transfer body 20. Then, it is determined whether or not the processing number N of the patch measurement process (S35) by the ADC sensor 27 and the actual density calculation process (S36) is smaller than the reference number (here, 3 times) (S41).

  If the number N of processings is smaller than the reference number (N <3; YES in S41), the process returns to S34, and again the patch creation process (S34), the patch measurement process (S35), and the measured density A calculation process (S36) is performed.

  When the above process is repeated and the above process number N reaches the reference number (N = 3; NO in S41), the process proceeds to S42, and the sensitivity acquisition unit 297 performs the previous unevenness correction process (exposure amount adjustment). The exposure sensitivity calculated in the adjustment process is acquired from the storage unit 293 (S42). The sensitivity acquisition unit 297 outputs the acquired exposure sensitivity to the control device 32. The storage unit 293 may store not only the exposure sensitivity calculated in the previous unevenness correction process, but also a plurality of exposure sensitivities calculated in the past unevenness correction process. Further, the calculated normal exposure sensitivity, that is, the exposure sensitivity used for controlling the exposure amount, is stored at the timing when the correction value output unit 323 of the control device 32 outputs the calculated exposure correction value to the exposure device 14. Is remembered.

  In S40, if the measured density is within the reference range (NO in S40), the process proceeds to S37, and the sensitivity calculation unit 292 performs exposure sensitivity based on the exposure amount of the patch and the calculated measured density. And the calculated exposure sensitivity is output to the control device 32 (S37). The subsequent processing is the same as the unevenness correction processing according to the second embodiment (see FIG. 9).

  According to the unevenness correction processing according to the third embodiment, since an abnormality occurring in the intermediate transfer body 20 or the like can be detected, more accurate unevenness correction can be performed and the number of times the determination process is repeated is limited. Therefore, the processing time for unevenness correction can be shortened.

  In the unevenness correction process according to the third embodiment, the initial density (predicted density shown in FIG. 6) may be used instead of the actually measured density calculated in the previous unevenness correction process.

  Here, in the first to third embodiments, the case where the image density (gradation) of the patch is Cin 45% is shown. The image density of the patch used for the unevenness correction processing is not particularly limited, but it is preferable to use a Cin 60% patch with the highest exposure sensitivity. FIG. 14 is a graph showing the relationship between Cin and exposure sensitivity (density change per 1% exposure dose). Further, each exposure sensitivity may be obtained from 0% to 100%, or exposure sensitivity of other image densities may be calculated from the exposure sensitivity of Cin 60% based on the correlation shown in FIG. For example, the exposure sensitivity of Cin 20% may be calculated as 40% (0.095 × 0.4 = 0.038) of the exposure sensitivity (0.0095) of Cin 60%. If the exposure sensitivity is calculated using the correlation as described above, the control time of the intermediate transfer member 20 can be shortened.

  In the second and third embodiments, it is determined whether or not the actually measured density is within a preset reference range based on the density (predicted density) for the same exposure amount. The configuration for determining abnormalities occurring in the above is not limited to this. For example, as a modification, the above determination processing for the actually measured density may not be performed, and it may be configured to determine whether or not the exposure sensitivity calculated thereafter is within a preset reference range. FIG. 16 shows a modification of the second embodiment, and FIG. 17 shows a modification of the third embodiment. Each modification includes an exposure sensitivity determination unit (not shown) that determines the exposure sensitivity, and the exposure sensitivity determination unit calculates the calculated exposure sensitivity and the exposure sensitivity as a reference value stored in the storage unit 293. Compare (S30 ', S40'). If the calculated exposure sensitivity is not within the preset reference range, patch creation (S24, S34), patch measurement (S25, S35), density calculation (S26, S36), and exposure sensitivity calculation (S27) , S37) is repeated. In the modification shown in FIG. 17, when the number N of processes is smaller than the reference number, the exposure sensitivity calculated in the previous unevenness correction process or the initial exposure sensitivity stored in the storage unit 293 is stored. To get.

  In the second and third embodiments, when the actually measured density is not within the reference range, a server (terminal) that remotely manages the image forming apparatus 10 may be notified of the abnormality of the intermediate transfer member 20. . Further, a configuration may be added in which an abnormal message is displayed on the image forming apparatus 10 to notify the user. As a result, it is possible to quickly respond (repair, replace, etc.) to an abnormality inside the image forming apparatus 10.

  In the unevenness correction processing according to the present embodiment, the test image direction of the test chart may be a direction parallel to or orthogonal to the scan direction of the test chart by the scanner 28. Also good. Specifically, for the test image made up of C, M, Y, and K colors shown in FIG. 15, the scan direction may be the X direction or the Y direction.

  The functions of the above-described units included in the image forming apparatus 10 described above are information that can be read by a computer including a control unit such as a CPU, a storage unit such as a memory, and an input / output unit that transmits and receives data to and from an external device. It may be realized by reading and executing a program stored in a storage medium. The program may be supplied to the image forming apparatus 10 which is a computer by an information storage medium such as an optical disk, a magnetic disk, a magnetic tape, a magneto-optical disk, a flash memory, or the image may be transmitted via a data communication network such as the Internet. It may be supplied to the forming apparatus 10.

  DESCRIPTION OF SYMBOLS 10 Image forming apparatus, 14 Exposure apparatus, 27 ADC sensor, 28 Scanner, 29 Exposure sensitivity calculating apparatus, 32 Control apparatus, 321 Density difference calculation part, 322 Correction value calculation part, 323 Correction value output part, 291 Density calculation part, 292 Sensitivity calculation unit, 293 storage unit, 294 density determination unit, 295 frequency measurement unit, 296 frequency comparison determination unit, 297 sensitivity acquisition unit

Claims (14)

Image creating means for creating a plurality of images with different exposure amounts on the intermediate transfer member;
Density calculating means for calculating the density of a plurality of images created on the intermediate transfer member;
Sensitivity calculating means for calculating an exposure sensitivity represented by a change amount of density with respect to a change amount of exposure amount, based on the exposure amount and the calculated density in each of the plurality of images;
Adjusting means for adjusting an exposure amount for a print image based on the calculated exposure sensitivity,
An image forming apparatus, wherein when the image densities of the plurality of images are different, the exposure sensitivity in another image is calculated based on the exposure sensitivity in the image having the highest exposure sensitivity. A density measuring means for measuring the density of a plurality of images created on the intermediate transfer member;
A storage unit for storing the measurement value of the concentration measurement unit and a preset concentration corresponding to the measurement value;
The image forming apparatus according to claim 1, wherein the density calculation unit acquires a density corresponding to a measurement value of the density measurement unit from the storage unit. An image capturing unit that captures the test image printed on the recording medium as image data into the image forming apparatus;
The image forming apparatus according to claim 1, wherein a process of calculating the exposure sensitivity is performed in parallel with the capturing process.   The image forming apparatus according to claim 3, further comprising density difference calculating means for calculating a density difference in the captured image data. A correction value calculating means for calculating an exposure correction value for adjusting the exposure amount;
The image forming apparatus according to claim 4, wherein the correction value calculation unit calculates the exposure correction value so as to reduce the density difference. A density determination unit that determines whether or not the densities of the plurality of images created on the intermediate transfer member calculated by the density calculation unit are within a preset reference range;
2. The image forming apparatus according to claim 1, wherein when the density is not within the reference range, the process by the image creating unit and the process by the density calculating unit are performed again.   7. The process according to claim 6, wherein when the density is not within the reference range, the process by the image creating unit and the process by the density calculation unit are repeatedly performed until the density falls within the reference range. Image forming apparatus. Image creating means for creating a plurality of images with different exposure amounts on the intermediate transfer member;
Density calculating means for calculating the density of a plurality of images created on the intermediate transfer member;
Sensitivity calculating means for calculating an exposure sensitivity represented by a change amount of density with respect to a change amount of exposure amount, based on the exposure amount and the calculated density in each of the plurality of images;
Adjusting means for adjusting the exposure amount for the print image based on the calculated exposure sensitivity;
A density determination unit that determines whether or not the densities of the plurality of images created on the intermediate transfer member calculated by the density calculation unit are within a preset reference range;
With
When the density is not within the reference range, the process by the image creating unit and the process by the density calculating unit are performed again,
When the density is within the reference range, the sensitivity calculation unit performs processing. A density determination unit that determines whether or not the densities of the plurality of images created on the intermediate transfer member calculated by the density calculation unit are within a preset reference range;
A frequency measuring means for measuring the number of times the processing by the image creating means and the processing by the density calculating means are performed,
2. The process according to claim 1, wherein when the density is not within the reference range, the process by the image creating unit and the process by the density calculating unit are repeated until the number of times reaches a preset reference number. The image forming apparatus described in 1. Image creating means for creating a plurality of images with different exposure amounts on the intermediate transfer member;
Density calculating means for calculating the density of a plurality of images created on the intermediate transfer member;
Sensitivity calculating means for calculating an exposure sensitivity represented by a change amount of density with respect to a change amount of exposure amount, based on the exposure amount and the calculated density in each of the plurality of images;
Adjusting means for adjusting the exposure amount for the print image based on the calculated exposure sensitivity;
A density determination unit that determines whether or not the densities of the plurality of images created on the intermediate transfer member calculated by the density calculation unit are within a preset reference range;
Number-of-times measuring means for measuring the number of times the processing by the image creating means and the processing by the density calculating means are performed;
With
If the density is not within the reference range, until the number of times reaches a preset reference number, repeat the processing by the image creation means and the density calculation means ,
When the concentration is within the reference range, the sensitivity calculation means performs processing.
When the density is not within the reference range and the number of times has reached the reference number of times, the adjusting unit applies a print image based on the exposure sensitivity calculated in the exposure amount adjustment process performed previously. An image forming apparatus that adjusts an exposure amount. Image creating means for creating a plurality of images with different exposure amounts on the intermediate transfer member;
Density calculating means for calculating the density of a plurality of images created on the intermediate transfer member;
Sensitivity calculating means for calculating an exposure sensitivity represented by a change amount of density with respect to a change amount of exposure amount, based on the exposure amount and the calculated density in each of the plurality of images;
Adjusting means for adjusting the exposure amount for the print image based on the calculated exposure sensitivity;
A density determination unit that determines whether or not the densities of the plurality of images created on the intermediate transfer member calculated by the density calculation unit are within a preset reference range;
Number-of-times measuring means for measuring the number of times the processing by the image creating means and the processing by the density calculating means are performed;
With
If the density is not within the reference range, until the number of times reaches a preset reference number, repeat the processing by the image creation means and the density calculation means ,
When the concentration is within the reference range, the sensitivity calculation means performs processing.
The adjusting means adjusts an exposure amount for a printed image based on an initial exposure sensitivity when the density is not within the reference range and the number of times reaches the reference number. Image forming apparatus. A storage unit for storing the exposure sensitivity calculated in the exposure amount adjustment process performed in the past;
Sensitivity acquisition means for acquiring the exposure sensitivity calculated in the previous exposure amount adjustment processing from the storage unit when the density is not within the reference range and the number of times reaches the reference number of times. The image forming apparatus according to claim 10, further comprising:   11. The image forming apparatus according to claim 7, wherein when the density is not within the reference range, an abnormality of the image forming apparatus is notified to a terminal that manages the image forming apparatus. Computer
Image creating means for creating a plurality of images with different exposure amounts on the intermediate transfer member;
Density calculating means for calculating the density of a plurality of images created on the intermediate transfer member;
Sensitivity calculating means for calculating an exposure sensitivity represented by a change amount of density with respect to a change amount of exposure amount, based on the exposure amount and the calculated density in each of the plurality of images;
An adjusting means for adjusting an exposure amount for a print image based on the calculated exposure sensitivity; and
A program for functioning as means for calculating the exposure sensitivity in another image based on the exposure sensitivity in an image having the highest exposure sensitivity when the image densities of the plurality of images are different.

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