Image forming device

Abstract

To provide an image formation apparatus capable of maintaining picture quality without making a print wait time long.SOLUTION: An image formation apparatus comprises an image formation part, a read part and a control part. The image formation part forms a first test image and also forms a second test image. The read part reads the first test image with a first light emission quantity corresponding to a first input value, and also reads the second test image with a second light emission quantity corresponding to a second input value. The control part selectively executes one of first, second and third correction stages according to an event change. The first correction processing stage includes first light quantity correction for correcting the first input value and image density correction based upon a read result of the first test image. The second correction processing stage includes second light quantity correction for correcting the second input value and the image density correction. The third correction processing stage includes color shift correction based upon a read result of the second test image.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to an image forming apparatus. [Background technology]

[0002] Electrophotographic image forming apparatuses are equipped with several correction functions for maintaining image quality, such as image density correction for correcting unevenness in image density and color misregistration correction for correcting color misregistration in the transfer positions of YMCK (yellow, magenta, cyan, and key (black)).

[0003] The image forming apparatus forms a test pattern for correcting image density or a test pattern for correcting color misregistration on an intermediate transfer belt, reads the test pattern with a sensor, and corrects the density or color misregistration based on the read result.

[0004] Image density correction and color misregistration correction have different purposes, so it is known that the light emission amount of the sensor is changed depending on the image density correction and color misregistration correction. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6562786 Summary of the Invention [Problem to be solved by the invention]

[0006] Because image forming devices vary in design from one device to another, the light emission intensity of the sensor is corrected to correct both image density and color misregistration. Binary search measurement is known as a method for correcting the light emission intensity of the sensor, but simply using binary search measurement to correct the light intensity for each correction would increase the time required for light intensity correction, resulting in longer print wait times.

[0007] The problem to be solved by the present invention is to provide an image forming apparatus that can maintain image quality without lengthening the print waiting time. [Means for solving the problem]

[0008] An image forming apparatus according to an embodiment includes an image forming unit, a reading unit, and a control unit. The image forming unit forms a first test image based on first test image data corresponding to multiple colors, and forms a second test image based on second test image data corresponding to multiple colors. The reading unit reads the first test image with a first light emission amount corresponding to a first input value, and reads the second test image with a second light emission amount corresponding to a second input value. The control unit selectively executes one of first, second, and third correction processes based on a change in an event. The first correction process includes a first light intensity correction that corrects the first input value to maintain the first light emission amount, and an image density correction based on the reading result of the first test image. The second correction process includes a second light intensity correction that corrects the second input value to maintain the second light emission amount, and the image density correction. The third correction process includes color misregistration correction based on the reading result of the second test image. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of an image forming apparatus according to an embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view showing an example of an image forming unit and its periphery according to an embodiment. [Figure 3] FIG. 3 is a block diagram showing an example of functions of the image forming apparatus according to the embodiment. [Figure 4] FIG. 4 is a diagram showing the relationship between the input voltage value (amount of light emitted) and the output voltage value (amount of light received) for the image quality maintenance sensor according to the embodiment. [Figure 5] FIG. 5 is a diagram showing a first example of execution timing (cycle) of automatic correction according to the embodiment. [Figure 6]FIG. 6 is a diagram showing a second example of the execution timing (cycle) of the automatic correction according to the embodiment. [Figure 7] FIG. 7 is a diagram illustrating an example of manual correction according to the embodiment. [Figure 8] FIG. 8 is a flowchart illustrating a first example of automatic correction according to the embodiment. [Figure 9] FIG. 9 is a flowchart illustrating a second example of automatic correction according to the embodiment. [Figure 10] FIG. 10 is a flowchart illustrating an example of manual correction according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described with reference to the drawings. Note that the scale of each part in each drawing used in the following description of the embodiments has been changed as appropriate. Furthermore, for the sake of explanation, the configuration of each drawing used in the following description of the embodiments has been omitted as appropriate.

[0011] [composition] FIG. 1 is a schematic cross-sectional view showing an example of an image forming apparatus according to an embodiment. The image forming apparatus 1 prints images by electrophotography. The image forming apparatus 1 is, for example, an MFP (multifunction peripheral). The image forming apparatus 1 includes an image reading unit 12, an image quality maintaining sensor 13, an image forming unit 14, and a fixing unit 15.

[0012] The image reading unit 12 reads an image of a document set on a document table and outputs read image data corresponding to the document image. The image forming unit 14 forms an output image on a sheet based on the read image data or input image data. The fixing unit 15 heats the sheet to fix the image formed on the sheet.

[0013] Image quality maintenance sensor 13 includes a light-emitting element and a light-receiving element. The light-emitting element emits light at an amount corresponding to an input value (input voltage), and the light from the light-emitting element is irradiated onto the surface of the intermediate transfer belt. The light-receiving element receives light reflected from the belt surface and outputs an output value (output voltage) corresponding to the amount of light received.

[0014] That is, the image quality maintenance sensor 13 functions as a reading unit, and reads the image of a first test pattern for image density correction or the image of a second test pattern for color shift correction formed on the intermediate transfer belt using a light-emitting unit and a light-receiving unit. Based on the results of reading the image of the first test pattern, the density of the image to be formed is corrected. Based on the results of reading the image of the second test pattern, color shift correction of the image to be formed is performed.

[0015] Furthermore, the image forming apparatus 1 includes a supply unit 16, a discharge unit 17, a conveyance path 106, conveyance rollers 107, and registration rollers 108. The supply unit 16 includes a plurality of supply cassettes 161, each of which stores a plurality of sheets. The supply unit 16 supplies the plurality of sheets stored in the supply cassettes 161 one by one. The conveyance rollers 107 convey the sheets from the supply unit 16 toward the discharge unit 17 along the conveyance path 106. The registration rollers 108 send the sheets toward the image forming unit 14. The discharge unit 17 includes a discharge tray 171, which receives the discharged sheets.

[0016] Furthermore, the image forming apparatus 1 includes a control panel 18 and a display 19. The control panel 18 receives input from a user or a service technician. For example, the control panel 18 receives an instruction to correct image density or an instruction to correct color misregistration. The display 19 displays various information. The control panel 18 and the display 19 may be configured using a touch panel that is responsible for display and input.

[0017] FIG. 2 is a schematic cross-sectional view showing an example of an image forming unit and its periphery according to an embodiment. The image forming unit 14 includes a process unit 141 corresponding to a plurality of colors. For example, the process unit 141 includes a process unit 1411 corresponding to yellow, a process unit 1412 corresponding to magenta, a process unit 1413 corresponding to cyan, and a process unit 1414 corresponding to black.

[0018] The image forming unit 14 also includes a toner cartridge 1451 and a toner supply motor 1461 corresponding to the process unit 1411, a toner cartridge 1452 and a toner supply motor 1462 corresponding to the process unit 1412, a toner cartridge 1453 and a toner supply motor 1463 corresponding to the process unit 1413, and a toner cartridge 1454 and a toner supply motor 1464 corresponding to the process unit 1414.

[0019] The toner cartridge 1451 is filled with yellow toner. The toner supply motor 1461 rotates a rotary stirring member provided inside the toner cartridge 1451, causing the toner to fall through a tube into the developing device 14041. In this way, the toner supply motor 1461 supplies the toner filled in the toner cartridge 1451 to the developing device 14041.

[0020] Toner cartridge 1452 has magenta toner filled therein, toner cartridge 1453 has cyan toner filled therein, and toner cartridge 1454 has black toner filled therein. Toner supply motor 1462 supplies the toner filled in toner cartridge 1452 to developing device 14042, toner supply motor 1463 supplies the toner filled in toner cartridge 1453 to developing device 14043, and toner supply motor 1464 supplies the toner filled in toner cartridge 1454 to developing device 14044.

[0021] The colors of toner handled by the image forming apparatus 1 are not limited to the above four colors and may be other colors. The toner handled by the image forming apparatus 1 may also be special toner. The special toner may be decolorizable toner that is decolorized and becomes invisible at a temperature higher than a predetermined temperature.

[0022] Furthermore, the image forming unit 14 includes a process unit 141, a secondary transfer roller 142, a secondary transfer opposing roller 143, and an intermediate transfer belt 144. The image quality maintenance sensor 13 is disposed opposite the belt surface of the intermediate transfer belt 144.

[0023] Based on image data, the process unit 141 forms a toner image on an endless belt, that is, an intermediate transfer belt 144. That is, the process units 1411, 1412, 1413, and 1414 form toner images of each color on the intermediate transfer belt 144 based on image data.

[0024] The secondary transfer opposing roller 143 faces the secondary transfer roller 142 across the intermediate transfer belt 144. The secondary transfer opposing roller 143 and the secondary transfer roller 142 sandwich a sheet therebetween and transport the sheet onto which an image has been transferred.

[0025] The process unit 1411 includes a photosensitive drum 14011, a charger 14021, an exposure device 14031, a developing device 14041, a photosensitive cleaner 14051, a primary transfer roller 14061, and a temperature sensor 14071. The process units 1412, 1413, and 1414 also have a similar configuration.

[0026] The photosensitive drum 14011 is a cylindrical drum that is an image carrier that carries an electrostatic latent image on its surface. The photosensitive drum 14011 has a photosensitive material on its outer periphery and has the property of discharging static electricity from the area irradiated with light.

[0027] The charger 14021 charges the surface of the photosensitive drum 14011 with static electricity. The charger 14021 is, for example, a needle electrode. The exposure device 14031 forms an electrostatic latent image corresponding to the image to be formed on the surface of the photosensitive drum 14011. The exposure device 14031 is, for example, a laser irradiation device. The development device 14041 supplies toner to the surface of the photosensitive drum 14011 and develops the electrostatic latent image with the toner.

[0028] The primary transfer roller 14061 transfers the electrostatic latent image developed on the surface of the photosensitive drum 14011 onto the intermediate transfer belt 144. The secondary transfer roller 142 transfers the toner image on the intermediate transfer belt 144 onto a sheet.

[0029] The photoconductor cleaner 14051 removes residual toner from the photoconductor drum 14011. The removed toner is collected in a waste toner box and disposed of.

[0030] The temperature sensor 14071 detects temperature changes in the process unit 1411. For example, the temperature sensor 14071 is installed near the exposure device 14031 and detects the effects of heat generated by the exposure device 14031. Color misalignment at the transfer positions of YMCK occurs due to the effects of expansion or contraction of each part caused by temperature changes inside the machine. The temperature change detected by the temperature sensor 14071 triggers the execution of color misalignment correction.

[0031] FIG. 3 is a block diagram showing an example of functions of the image forming apparatus according to the embodiment. 3, the image forming apparatus 1 includes an image reading unit 12, an image quality maintaining sensor 13, an image forming unit 14, a fixing unit 15, a supply unit 16, a discharge unit 17, a control panel 18, and a display 19. The image reading unit 12 and the image forming unit 14 are connected via an image data bus 110.

[0032] The image forming unit 14 includes page memories 1471, 1472, 1473, and 1474, a light emission controller 148, and a process unit 141. The page memory 1471 outputs yellow image data included in the read image data, the page memory 1472 outputs magenta image data included in the read image data, the page memory 1473 outputs cyan image data included in the read image data, and the page memory 1474 outputs black image data included in the read image data.

[0033] The light emitting controller 148 is connected to each of the page memories 1471, 1472, 1473, and 1474, and receives yellow image data from the page memory 1471, magenta image data from the page memory 1472, cyan image data from the page memory 1473, and black image data from the page memory 1474.

[0034] The light emission controller 148 controls the light emission of the exposure device 14031 based on yellow image data from the page memory 1471, controls the light emission of the exposure device 14032 based on magenta image data from the page memory 1472, controls the light emission of the exposure device 14033 based on cyan image data from the page memory 1473, and controls the light emission of the exposure device 14034 based on black image data from the page memory 1474.

[0035] Furthermore, the image forming apparatus 1 includes a controller 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, a non-volatile memory 104, a communication I / F (interface) 105, and a mechanical control driver 109.

[0036] The controller 101 is connected to each unit, outputs signals to each unit, and inputs signals from each unit. The controller 101 is composed of one or more processors. The processor may be a CPU (central processing unit), an MPU (micro processing unit), a DSP (digital signal processor), or the like. The controller 101 controls operations such as image reading and formation in accordance with various programs stored in at least one of the ROM 102 and the nonvolatile memory 104, and also functions as a control unit that controls the first to ninth correction processes described below. The controller 101 also outputs operation instructions for the motors and the like to a mechanical control driver 109.

[0037] ROM 102 stores some or all of the various programs and various parameters required for the control of controller 101. RAM 103 temporarily stores data required for the control of controller 101. Non-volatile memory 104 stores some or all of the various programs and various parameters. For example, non-volatile memory 104 stores input values ​​(first and second input values) input to the light-emitting element of image quality maintenance sensor 13. The input values ​​are corrected at the light intensity correction timing, and non-volatile memory 104 also stores the corrected input values ​​(first and second input values).

[0038] The mechanical control driver 109 controls the operation of the motors and the like in accordance with operation instructions from the controller 101 .

[0039] The communication I / F 105 communicates with the outside. For example, the communication I / F 105 inputs image data output from a personal computer or the like. The image forming unit 14 forms an image based on the input image data. The communication I / F 105 also transmits maintenance information to a server. The server receives the maintenance information and manages the maintenance status of the image forming device 1.

[0040] [Operation] The image forming apparatus 1 has several correction functions for maintaining image quality. For example, the image forming apparatus 1 has an image density correction function for correcting unevenness in image density, and a color misregistration correction function for correcting misalignment in the transfer positions of YMCK dots.

[0041] The controller 101, the image forming unit 14, and the image quality maintenance sensor 13 cooperate to perform image density correction. Based on instructions from the controller 101, the image forming unit 14 forms a first test image on the intermediate transfer belt 144 based on first test image data corresponding to multiple colors for image density correction. Based on instructions from the controller 101, the image quality maintenance sensor 13 reads the image of the first test pattern for image density correction formed on the intermediate transfer belt 144 with a first light emission amount corresponding to a first input value. The controller 101 outputs a correction signal based on the reading result of the image (shade) of the first test pattern. The light emission controller 148 controls light emission based on the correction signal and the image data of each page memory.

[0042] Furthermore, the controller 101, the image forming unit 14, and the image quality maintenance sensor 13 cooperate to perform color shift correction. Based on instructions from the controller 101, the image forming unit 14 forms a second test image on the intermediate transfer belt 144 based on second test image data corresponding to multiple colors for color shift correction. Based on instructions from the controller 101, the image quality maintenance sensor 13 reads an image (color shift) of a second test pattern for color shift correction with a second light emission amount corresponding to a second input value. The second light emission amount is greater than the first light emission amount. The controller 101 outputs a correction signal based on the reading result of the image of the second test pattern. The light emission controller 148 controls light emission based on the correction signal and the image data of each page memory.

[0043] The reading performance of the image quality maintenance sensor 13 varies from one sensor to another due to differences in the amount of light emitted by the light-emitting element, and its performance may change due to deterioration over time or the accumulation of dirt. Also, the gloss level of the intermediate transfer belt 144 may differ from one sensor to another.

[0044] The controller 101 controls the first and second light emission intensities of the image quality maintenance sensor 13 to the target light emission intensities in order to maintain constant reading performance of the image quality maintenance sensor 13. For example, the controller 101 corrects the first and second light emission intensities of the image quality maintenance sensor 13 using a method such as binary search disclosed in Japanese Patent No. 6562786. The controller 101 controls the first and second light emission intensities of the image quality maintenance sensor 13 to the target light emission intensities by correcting the first and second input values.

[0045] 4 is a diagram showing the relationship between the input voltage value (amount of light emitted) and the output voltage value (amount of light received) for the image quality maintenance sensor according to the embodiment. The horizontal axis Vref [V] in FIG. 4 represents the input voltage value (amount of light emitted), and the vertical axis Vout [V] represents the output voltage value (amount of light received).

[0046] In image density correction, the density is corrected based on the detection results (output voltage values) of the toner adhesion areas corresponding to the image of the first test pattern, while in color misregistration correction, the color misregistration is corrected based on the detection results (output voltage values) of the toner adhesion areas and the transition points on the belt surface corresponding to the image of the second test pattern.

[0047] As shown in Figure 4, gray, which is the result of detecting the toner adhesion area used for image density correction, has a small effect on the output voltage value relative to the input voltage value, while black, which is the result of detecting the toner adhesion area and the transition point on the belt surface used for color misregistration correction, has a large effect on the output voltage value relative to the input voltage value. In other words, the glossy belt surface is more affected by deterioration over time or dirt (reduction in light emission amount), which are factors that change the amount of light emission, than the toner adhesion area. Therefore, the image forming apparatus 1 performs the second light intensity correction for color misregistration correction more frequently than the first light intensity correction for image density correction.

[0048] As described above, the first and second light emission intensities of the image quality maintenance sensor 13 are corrected using a method such as binary search. However, if both the first light intensity correction for correcting the first light emission intensity and the second light intensity correction for correcting the second light emission intensity are performed in a series of correction processes, the overall processing time will be long. Therefore, the image forming apparatus 1 of this embodiment selectively performs either the first light intensity correction or the second light intensity correction in a series of correction processes. This prevents the overall processing time from being long.

[0049] FIG. 5 is a diagram showing a first example of execution timing (cycle) of automatic correction according to the embodiment. The controller 101 of the image forming apparatus 1 selectively executes one of the first, second, and third correction processes based on the execution conditions (event changes). The controller 101 also executes the second correction process more frequently than the first correction process.

[0050] The correction processes are as follows. The first correction process includes a first light intensity correction (a) that corrects a first input value so as to maintain a first light intensity, and an image density correction (A) based on the reading result of a first test image read with a first light intensity corresponding to the first input value (first correction process: (a)+(A)).

[0051] The second correction process also includes a second light intensity correction (b) that corrects the second input value so as to maintain the second light intensity, and an image density correction (A) based on the reading result of the first test image read with the first light intensity corresponding to the first input value (second correction process: (b) + (A)).

[0052] The third correction process also includes color shift correction (B) based on the reading result of a second test image read with a second light emission amount corresponding to a second input value (third correction process: (B)).

[0053] The controller 101 selectively executes either the first or second correction process in response to a first event change, and executes a third correction process in response to a second event change. The first event change is the number of output images formed, and the second event change is a temperature change detected by the temperature sensors 14071, 14072, 14073, and 14074.

[0054] 5, when the number of sheets on which output images have been formed reaches 1000, the controller 101 executes the second correction process at the timing when 1000 sheets are reached, the timing when the series of image forming operations that have reached 1000 sheets end, or at any timing between the end of this series of image forming operations and the start of the next image forming operation. For example, the controller 101 executes the second light intensity correction (b) (after correcting the second input value), and then executes the image density correction (A) based on the reading result of the first test image that is read with the first light intensity corresponding to the first input value.

[0055] Similarly, when the number of sheets on which output images have been formed reaches 2000 and 3000, the controller 101 executes the second correction process.

[0056] Furthermore, when the number of sheets on which output images have been formed reaches 10,000, the controller 101 executes a first correction process at the timing when 10,000 sheets are reached, at the timing when the series of image forming operations that reached 10,000 sheets ends, or at any timing between the end of this series of image forming operations and the start of the next image forming operation. For example, the controller 101 executes a first light intensity correction (a) (after correcting the first input value), and then executes an image density correction (A) based on the reading result of a first test image that is read with a first light intensity that corresponds to the corrected first input value.

[0057] Similarly, when the number of sheets on which output images have been formed reaches 20,000 and 30,000, the controller 101 executes the first correction process.

[0058] Furthermore, the controller 101 executes a third correction process at the timing when the temperature values ​​detected by the temperature sensors 14071, 14072, 14073, and 14074 exceed a temperature threshold stored in the nonvolatile memory 104, at the timing when the series of image forming operations that caused the temperature threshold to be exceeded ends, or at any timing between the end of this series of image forming operations and the start of the next image forming operation. For example, the controller 101 executes color misregistration correction (B) based on the reading result of a second test image read with a second light emission amount corresponding to a second input value.

[0059] As described above, the image forming apparatus 1 according to the embodiment executes the second correction process at a predetermined timing every 1,000 sheets (excluding every 10,000 sheets), and executes the first correction process at a predetermined timing every 10,000 sheets. This prevents the image forming apparatus 1 from executing both the first light intensity correction (a) and the second light intensity correction (b) in a series of correction processes, thereby preventing the series of correction processes from taking too long. Furthermore, the image forming apparatus 1 executes the second light intensity correction (b) for color misregistration correction more frequently than the first light intensity correction (a) for image density correction, thereby achieving both maintaining image quality and reducing processing time.

[0060] Alternatively, the controller 101 may execute the second correction process at a predetermined timing when the number of sheets on which output images have been formed reaches 1,000, 2,000, or 3,000, execute the first correction process at a predetermined timing when the number of sheets on which output images have been formed reaches 10,500, 20,500, or 30,500, and execute the third correction process at a predetermined timing when the detected temperature value exceeds the temperature threshold. In this case, the same effect as above can be obtained.

[0061] FIG. 6 is a diagram showing a second example of the execution timing (cycle) of the automatic correction according to the embodiment. The controller 101 of the image forming apparatus 1 selectively executes one of the first, second, third, and fourth correction processes based on the execution conditions (event changes). The controller 101 also executes the second correction process more frequently than the first correction process.

[0062] The correction processes are as follows. The first, second, and third correction processes are as described above. The fourth correction process does not include the first light amount correction (a) and the second light amount correction (b), but includes the image density correction (A) (fourth correction process: (A)).

[0063] The controller 101 selectively executes one of the first, second, and fourth correction processes in response to the first event change, and executes the third correction process in response to the second event change. The first and second event changes are as described above.

[0064] 6, when the number of sheets on which output images have been formed reaches 1000, the controller 101 executes the second correction process at the timing when 1000 sheets are reached, the timing when the series of image forming operations that have reached 1000 sheets end, or at any timing between the end of this series of image forming operations and the start of the next image forming operation. For example, the controller 101 executes the second light intensity correction (b) (after correcting the second input value), and then executes the image density correction (A) based on the reading result of the first test image that is read with the first light intensity corresponding to the first input value.

[0065] Furthermore, the controller 101 executes the fourth correction process when the number of sheets on which output images have been formed reaches 2000, when the number of sheets on which output images have been formed reaches 2000, when the series of image forming operations that have reached 2000 ends, or at any timing between the end of this series of image forming operations and the start of the next image forming operation. For example, the controller 101 executes the image density correction (A) based on the reading result of the first test image that is read with the first light emission amount corresponding to the first input value, without executing the first light intensity correction (a) and the second light intensity correction (b).

[0066] Similarly, the controller 101 executes the second correction process when the number of sheets on which output images have been formed reaches 3000 and 5000, and executes the fourth correction process when the number reaches 4000 and 6000.

[0067] Furthermore, when the number of sheets on which output images have been formed reaches 10,000, the controller 101 executes a first correction process at the timing when 10,000 sheets are reached, at the timing when the series of image forming operations that reached 10,000 sheets ends, or at any timing between the end of this series of image forming operations and the start of the next image forming operation. For example, the controller 101 executes a first light intensity correction (a) (after correcting the first input value), and then executes an image density correction (A) based on the reading result of a first test image that is read with a first light intensity that corresponds to the corrected first input value.

[0068] Similarly, when the number of sheets on which output images have been formed reaches 20,000 and 30,000, the controller 101 executes the first correction process.

[0069] Furthermore, the controller 101 executes a third correction process at the timing when the detected temperature value exceeds a temperature threshold stored in the nonvolatile memory 104, the timing when the series of image forming operations that caused the temperature threshold to be exceeded ends, or any timing between the end of the series of image forming operations and the start of the next image forming operation. For example, the controller 101 executes color misregistration correction (B) based on the reading result of a second test image read with a second light emission amount corresponding to a second input value.

[0070] As described above, the image forming apparatus 1 according to the embodiment alternately performs the second and fourth correction processes at predetermined timings every 1,000 sheets (excluding every 10,000 sheets), and performs the first correction process at predetermined timings every 10,000 sheets. This prevents the image forming apparatus 1 from performing both the first light intensity correction (a) and the second light intensity correction (b) in a series of correction processes. Furthermore, by reducing the frequency of the second light intensity correction (b), the series of correction processes can be prevented from taking a long time. Furthermore, the image forming apparatus 1 performs the second light intensity correction (b) for color misregistration correction more frequently than the first light intensity correction (a) for image density correction, thereby maintaining image quality and reducing processing time.

[0071] FIG. 7 is a diagram illustrating an example of manual correction according to the embodiment. The controller 101 performs image density correction (A), first light intensity correction (a), color misregistration correction (B), and second light intensity correction (b) either singly or in combination based on correction instructions input via the control panel 18.

[0072] For example, the display 19 displays a list of the first to ninth correction instructions and the details of the correction to be performed, as shown in Fig. 7. The user or service person selects and inputs one of the first to ninth correction instructions via the control panel 18.

[0073] The controller 101 executes image density correction (A) based on the input of a first correction instruction. The controller 101 executes color misregistration correction (B) based on the input of a second correction instruction. The controller 101 executes first light intensity correction (a) based on the input of a third correction instruction. The controller 101 executes second light intensity correction (b) based on the input of a fourth correction instruction.

[0074] Furthermore, the controller 101 executes the first light intensity correction (a) and image density correction (A) based on the input of a fifth correction instruction. Furthermore, the controller 101 executes the second light intensity correction (b) and color misregistration correction (B) based on the input of a sixth correction instruction. Furthermore, the controller 101 executes the second light intensity correction (b) and image density correction (A) based on the input of a seventh correction instruction.

[0075] Furthermore, the controller 101 executes the first light intensity correction (a), the second light intensity correction (b), and the image density correction (A) based on the input of an eighth correction instruction. Furthermore, the controller 101 executes the first light intensity correction (a), the second light intensity correction (b), the image density correction (A), and the color misregistration correction (B) based on the input of a ninth correction instruction.

[0076] The image forming apparatus 1 can perform each correction individually or in combination with multiple corrections at any timing based on input from a user or a service technician. For example, the image forming apparatus 1 can perform each correction individually or in combination with multiple corrections during the manufacturing process or initial setting.

[0077] 5 to 7, the controller 101 automatically or manually executes the correction process, and further stores the history of the correction process in the nonvolatile memory 104. For example, the history of the correction process includes the trigger of the correction process (the type of event that occurred) and the date and time of execution. The communication I / F 105 transmits identification information unique to the image forming apparatus 1 and the history of the correction process to the server at a predetermined timing. The server manages the history of the correction process executed by each image forming apparatus 1 based on the history of the correction process.

[0078] FIG. 8 is a flowchart illustrating a first example of automatic correction according to the embodiment. The controller 101 monitors changes in events. For example, when the number of printed sheets reaches 1,000, the controller 101 determines that the first condition is met (ST101, YES) and executes the second correction process at a predetermined timing (ST102). The second correction process includes a second light intensity correction (b) and a density correction (A). Furthermore, when the number of printed sheets reaches 2,000, the controller 101 again determines that the first condition is met (ST101, YES) and executes the second correction process at a predetermined timing (ST102).

[0079] Thereafter, when the number of printed sheets reaches 10,000, the controller 101 determines that the second condition is met (ST103, YES), and executes the first correction process at a predetermined timing (ST104). The first correction process includes a first light intensity correction (a) and a density correction (A).

[0080] Furthermore, when the detected temperature value exceeds the temperature threshold value, the controller 101 determines that the third condition is satisfied (ST105, YES), and executes the third correction process at a predetermined timing (ST106).

[0081] The controller 101 repeats ST101 to ST106 while continuing the correction control (ST107, NO).

[0082] FIG. 9 is a flowchart illustrating a second example of automatic correction according to the embodiment. The controller 101 monitors changes in events. For example, when the number of printed sheets reaches 1,000, the controller 101 determines that the fourth condition is met (ST201, YES) and executes the fourth correction process at a predetermined timing (ST202). The fourth correction process does not include the first light intensity correction (a) or the second light intensity correction (b), but does include density correction (A). When the number of printed sheets reaches 2,000, the controller 101 determines that the first condition is met (ST203, YES) and executes the second correction process at a predetermined timing (ST204).

[0083] Furthermore, when the number of printed sheets reaches 3000, the controller 101 again determines that the fourth condition is met (ST201, YES) and executes the fourth correction process at a predetermined timing (ST202).When the number of printed sheets reaches 4000, the controller 101 again determines that the first condition is met (ST203, YES) and executes the second correction process at a predetermined timing (ST204).

[0084] Thereafter, when the number of printed sheets reaches 10,000, the controller 101 determines that the second condition is met (ST205, YES), and executes the first correction process at a predetermined timing (ST206). The first correction process includes a first light intensity correction (a) and a density correction (A).

[0085] Furthermore, when the detected temperature value exceeds the temperature threshold value, the controller 101 determines that the third condition is satisfied (ST207, YES), and executes the third correction process at a predetermined timing (ST208).

[0086] The controller 101 repeats ST201 to ST208 while continuing the correction control (ST209, NO).

[0087] FIG. 10 is a flowchart illustrating an example of manual correction according to the embodiment. When a correction instruction is input via the control panel 18 (ST301, YES), the controller 101 performs image density correction (A), first light intensity correction (a), color misregistration correction (B), and second light intensity correction (b) either singly or in combination based on the input correction instruction (ST302).

[0088] In the present embodiment, the correction process is executed using the execution conditions (occurrence of an event) shown in Figures 5 and 8 or Figures 6 and 9 as triggers for the correction process. However, the execution conditions are not limited to these, and a service person or the like may arbitrarily set or change the execution conditions via the control panel 18. For example, instead of the 1000-sheet cycle, the cycle may be changed to 2000-sheet cycle or 3000-sheet cycle, and instead of the 10000-sheet cycle, the cycle may be changed to 20000-sheet cycle.

[0089] Furthermore, the controller 101 may change the frequency of density correction based on the result of density correction, or may change the frequency of color misregistration correction based on the result of color misregistration correction.

[0090] Furthermore, the communication I / F 105 communicates with the server, receives an operation program and the like at a predetermined timing, and the controller 101 updates the operation program stored in the nonvolatile memory 104 with the received operation program. The server may use this update of the operation program to change the trigger.

[0091] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0092] 1...Image forming device 12...Image reading unit 13...Image quality maintenance sensor 14...Image forming unit 15...Fixing part 16…Supply section 17...Discharge section 18...Control Panel 19...Display 101...Controller 102...ROM 103...RAM 104...Non-volatile memory 106...Transport path 107...Transport roller 108...Registration roller 109...Mechanical control driver 110...Image data bus 141...Process section 142...Secondary transfer roller 143...Secondary transfer opposing roller 144...Intermediate transfer belt 148...Lighting controller 161...Supply cassette 171...Outlet tray 1411...Processing section 1451...Toner cartridge 1461...Toner supply motor 1471...Page memory 14011...Photosensitive drum 14021...Charger 14031...Exposure equipment 14041...Developing device 14051...Photosensitive drum cleaner 14061...Primary transfer roller 14071...Temperature sensor

Claims

1. an image forming unit that forms a first test image based on first test image data corresponding to a plurality of colors, and that forms a second test image based on second test image data corresponding to a plurality of colors; a reading unit that reads the first test image with a first light emission amount corresponding to a first input value, and reads the second test image with a second light emission amount corresponding to a second input value; a control unit that selectively executes one of the first, second, and third correction processes based on an event change; the first correction process includes a first light amount correction that corrects the first input value so as to maintain the first light emission amount, and an image density correction based on a reading result of the first test image, the second correction process includes a second light amount correction that corrects the second input value so as to maintain the second light emission amount, and the image density correction; The third correction process includes color misregistration correction based on the reading result of the second test image.

2. the image forming unit forms an output image based on input image data; 2. The image forming apparatus of claim 1, wherein the control unit selectively executes one of the first and second correction processes in accordance with a performance record of forming the output image, and executes the third correction process in accordance with a temperature change.

3. The image forming apparatus of claim 1 , wherein the control unit executes the second correction process more frequently than the first correction process.

4. the control unit executes a fourth correction process in response to a change in an event; 2. The image forming apparatus of claim 1, wherein the fourth correction process does not include the first and second light amount corrections, but includes the image density correction.

5. the control unit executes a fifth correction process based on an input of a correction instruction; The image forming apparatus of claim 1 , wherein the fifth correction process includes the first light amount correction, the second light amount correction, and the image density correction.

Images