JP6083422B2 - Image forming apparatus, image forming method, and program - Google Patents

Description

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

  Conventionally, in a system including an image forming apparatus and an external device such as a personal computer (PC) connected to the image forming apparatus, a correction pattern image is formed by the image forming apparatus, and the external apparatus further performs the correction. A technique is known in which an image to be printed is corrected based on correction data obtained from a pattern image, and printing based on the corrected image is performed by an image forming apparatus.

  As a patent document disclosing the above system, for example, there is Patent Document 1. In Patent Document 1, a system including a printer, a PC, and a calibration curve creation device, a configuration in which a correction pattern image is output by the printer, and a reading result of the pattern image by the calibration curve creation device. A configuration for generating correction data based on the above and transmitting the correction data to a PC, and a configuration for correcting an image to be printed using the correction data by the PC are disclosed.

JP 11-252386 A

  However, the conventional technique described above has the following problems. For example, even when a pattern image is generated in a state where toner charging is unstable, the reliability of correction data obtained from the pattern image is low. Even if the image is corrected using such low-reliability correction data, there is a possibility that sufficient image quality cannot be obtained.

  The present invention has been made to solve the above-described problems of the prior art. That is, the problem is to provide a technique for suppressing deterioration in image quality in a system that corrects an image to be printed using correction data based on a reading result of a pattern image formed by an image forming apparatus. It is in.

  An image forming apparatus for solving this problem includes an image forming unit that forms an image, a sensor, and a control unit, and the control unit forms a pattern image for correction in the image forming unit. A pattern forming process, a pattern reading process for causing the sensor to read the pattern image formed in the pattern forming process, and a pattern image formed in the first pattern forming process in the first pattern reading process. Whether or not the difference between the read data relating to the read result and the data relating to the read result obtained by reading the pattern image formed in the second pattern forming process in the second pattern reading process is within an allowable range. And determining that the difference is within the permissible range in the determination process. The transmission target data is data relating to at least one of the reading results of the reading result of the reading process and the second of said pattern reading process, it is characterized by performing a transmission process of transmitting to an external device.

  An image forming apparatus disclosed in this specification reads a correction pattern formed in an image forming unit, and acquires data related to a read result. Then, the image forming apparatus executes the pattern forming process and the pattern reading process twice, and determines whether or not the difference between the data relating to the first reading result and the data relating to the second reading result is within an allowable range. To do. Then, in response to determining that it is within the allowable range, data related to at least one of the first and second reading results is transmitted to the external device.

  If the difference between the data related to the first reading result and the data related to the second reading result is not within the allowable range, it is highly likely that the reliability of the formed pattern image is low. That is, it is unlikely that a highly accurate reading result will be obtained. In the image forming apparatus disclosed in this specification, transmission target data is transmitted to an external apparatus on condition that the difference between the first and second reading results is small. As a result, high-accuracy correction based on highly reliable transmission target data can be expected by an external device.

  The image forming apparatus disclosed in the present specification further includes a container that contains toner and a stirring unit that stirs the toner contained in the container, and the image forming unit is contained in the container. An image is formed using the toner thus formed. When the pattern image is formed in the pattern forming process, the toner is stirred in the stirring unit, and the control unit performs the second process in the transmission process. The data related to the reading result of the pattern reading process may be transmitted to the external device. At the time of forming the second pattern image, the toner is agitated more than the first time, so that it is estimated that the charged state is more stable. Therefore, if data related to the reading result of the second pattern reading process is transmitted, more reliable data can be transmitted.

  In addition, when the control unit receives a transmission instruction for the transmission target data after the first pattern reading process is completed and before transmission of the transmission target data is started in the transmission process, It is preferable to execute an early transmission process for transmitting data related to the reading result of the pattern reading process to the external device. If the transmission instruction of the transmission target data is received before the transmission of the transmission target data is started, it is estimated that the urgency of the transmission target data is high. Therefore, for example, even if the second pattern reading process is not completed, it is desirable to exceptionally achieve early transmission completion by transmitting data related to the reading result of the first pattern reading process.

  The control unit may execute the early transmission process when the received transmission instruction is a transmission instruction based on a monochrome image printing instruction. In monochrome printing, high image quality tends not to be required. Therefore, even if printing is performed based on data related to the reading result of the first pattern reading process, it is difficult for the user to be dissatisfied. Therefore, it is preferable to achieve early completion of printing. On the other hand, high quality is required for color printing. For this reason, it is preferable not to transmit data related to the reading result of the first pattern reading process and not to perform printing based on the data related to the reading result of the first pattern reading process.

  Further, the control unit executes a generation process for generating correction data based on a reading result in the pattern reading process, and in the transmission process, the control unit is generated based on a reading result of the first pattern reading process. Data regarding at least one of the correction data and the correction data generated based on the reading result of the second pattern reading process may be the transmission target data. Since the image forming apparatus generates correction data, it is possible to reduce the load of generating correction data for each external apparatus.

  The control unit may start the generation process based on the first pattern reading process before the second pattern reading process is completed. By generating the correction data earlier, the determination process or the transmission process can be started earlier.

  In the pattern forming process, the control unit causes the image forming unit to form the pattern image related to a plurality of density gradations. In the determination process, whether the difference is within an allowable range for each density gradation. If at least one of the plurality of density gradations has a density gradation outside the allowable range, it may be determined that it is outside the allowable range. If there is even one density gradation outside the allowable range, there is a high possibility that appropriate density gradation correction will not be achieved. For this reason, if there is a density gradation that is outside the allowable range in at least one of the plurality of density gradations, it may be determined that it is outside the allowable range.

  In addition, when it is determined in the determination process that the difference is out of the allowable range, the control unit executes the pattern formation process and the pattern reading process again, and performs the previous pattern formation process. The difference between the data relating to the read result obtained by reading the formed pattern image by the pattern reading process and the data relating to the read result obtained by reading the pattern image formed by the current pattern forming process by the pattern reading process is acceptable. It is good to judge whether it is within the range. By executing the pattern forming process and the pattern reading process again, the possibility that the difference falls within the allowable range is increased, and the possibility that the transmission target data can be transmitted to the external apparatus is also increased. Note that the previous pattern reading process is a pattern forming process to be executed again and a pattern reading process executed immediately before the pattern reading process, and is the latest reading result, which is preferable as a comparison target.

  Further, the image forming apparatus disclosed in the present specification is provided with the image forming unit different for each color of toner. In the pattern forming process, the pattern image is formed for each color. In the determination process, for each color or combination of colors, it is determined whether the difference is within an allowable range, and the color for which the difference is determined to be outside the allowable range, or the difference is When there is a combination of colors determined to be outside the allowable range, the pattern image may be formed again for the color or color combination determined to be out of the allowable range in the pattern forming process to be executed again. By limiting the color for forming the pattern image again, waste of the colorant can be reduced.

  Further, the image forming apparatus disclosed in the present specification is provided with the image forming unit that is different for each color of toner, and the control unit determines the difference for each color or each combination of colors in the determination process. In the determination process, at least one color out of the allowable range or a combination of colors out of the allowable range is included in the determination process. If there are two, it is good to determine that they are outside the allowable range. If at least one color or combination of colors is out of the allowable range, it can be expected to transmit the transmission target data with higher accuracy by determining that it is out of the allowable range.

  A control method for realizing the functions of the image forming apparatus, a computer program, and a computer-readable storage medium storing the computer program are also novel and useful.

  According to the present invention, a technique for suppressing deterioration in image quality is realized in a system that corrects an image to be printed using correction data based on a reading result of a pattern image formed by an image forming apparatus.

1 is a block diagram illustrating an electrical configuration of a printer according to an embodiment. FIG. 2 is a cross-sectional view illustrating an internal configuration of the printer illustrated in FIG. 1. It is a schematic diagram which shows the structure of a developing device. It is a figure which shows arrangement | positioning of a mark sensor. It is explanatory drawing which shows the example of the printing procedure in a printer. It is a figure which shows the example of a density mark. It is a figure which shows the example of a density gradation mark. 6 is a flowchart illustrating a procedure of correction transmission processing of a printer. It is a flowchart which shows the procedure in the case of calculating a difference with PC. 6 is a flowchart illustrating a procedure of correction transmission processing of a printer.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an image forming apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. In this embodiment, the present invention is applied to a printer that forms an image by electrophotography.

  As shown in FIG. 1, the printer 100 of this embodiment includes a controller 30 including a CPU 31, a ROM 32, a RAM 33, a nonvolatile RAM (NVRAM) 34, and an ASIC 35. Furthermore, the printer 100 includes an image forming unit 10, a mark sensor 25, an operation panel 40, and a communication IF 38, which are connected to the controller 30. Note that the controller 30 in FIG. 1 is a collective term for hardware used for controlling the printer 100 such as the CPU 31, and does not necessarily represent a single piece of hardware that actually exists in the printer 100.

  The ROM 32 stores various control programs for controlling the printer 100, various settings, initial values, and the like. The RAM 33 is used as a work area from which various control programs are read, or as a storage area for temporarily storing data. The CPU 31 controls each component of the printer 100 while storing the processing result in the RAM 33 or the NVRAM 34 according to the control program read from the ROM 32. The CPU 31 is an example of a control unit. The controller 30 may be a control unit, and the ASIC 35 may be a control unit.

  The image forming unit 10 is configured to print an image on a sheet by electrophotography. The image forming unit 10 can form a color image. The mark sensor 25 reads the correction pattern image formed by the image forming unit 10. The correction will be described later. The operation panel 40 includes a liquid crystal display and various buttons, and receives an instruction input from the user.

  The communication IF 38 is hardware for communicating with other devices. Specifically, the communication IF 38 corresponds to various interfaces such as a wireless LAN, a wired LAN, and a USB, for example. The printer 100 is connected to the PC 200 via the communication IF 38. The PC 200 incorporates a printer driver corresponding to the printer 100 and transmits printing data to the printer 100. The printer 100 receives printing data from the PC 200 and executes printing based on the received data. A plurality of PCs 200 may be connected to one printer 100, or a plurality of printers 100 may be connected to one PC 200.

  Next, the configuration of the image forming unit 10 of the printer 100 will be described with reference to FIG. The image forming unit 10 forms a toner image by an electrophotographic method, transfers the toner image to a sheet, an exposure device 53 that irradiates the process unit 50 with light, and unfixed toner on the sheet. A fixing device 8 for fixing, a paper feed tray 91 for placing a sheet before image transfer, a paper discharge tray 92 for placing a sheet after image transfer, and a transport belt for transporting the sheet to a transfer position of the process unit 50 7.

  Further, in the printer 100, the sheet stored in the paper feed tray 91 located at the bottom passes through the paper feed roller 21, the registration roller 22, the process unit 50, and the fixing device 8, and passes through the paper discharge roller 26. As shown by a one-dot chain line in FIG. 2, a substantially S-shaped transport path 11 is provided so as to be guided to the paper discharge tray 92.

  In the process unit 50, process units corresponding to each color of cyan (C), magenta (M), yellow (Y), and black (K) are arranged in parallel. Specifically, a process unit 50C that forms an image of C color, a process unit 50M that forms an image of M color, a process unit 50Y that forms an image of Y color, and a process unit that forms an image of K color 50K. The process units 50 </ b> C, 50 </ b> M, 50 </ b> Y, and 50 </ b> K for each color are arranged along the conveyance belt 7 at equal intervals. The order of the process units is not limited to the example shown in FIG.

  The process unit 50K includes a drum-shaped photosensitive member 1, a charging device 2 that uniformly charges the surface of the photosensitive member 1, and a developing device 4 that develops the electrostatic latent image on the photosensitive member 1 with toner. , And a transfer device 5 that transfers the toner image on the photosensitive member 1 to a sheet or a conveyance belt 7. The photoreceptor 1 and the transfer device 5 are disposed in contact with the transport belt 7. The photosensitive member 1 is opposed to the transfer device 5 with the conveyance belt 7 interposed therebetween. The other process units 50C, 50M, and 50Y have the same configuration as the process unit 50K.

  Specifically, as illustrated in FIG. 3, the developing device 4 includes a developing unit 60 and a toner storage unit 70, and the space between both is connected through a supply port 69. In this embodiment, a nonmagnetic one-component toner is accommodated in the toner accommodating portion 70 as a developer. The toner container 70 is an example of a container.

  The developing unit 60 includes a developing roller 61 that carries toner and conveys the toner toward the photoreceptor 1, and a toner supply roller that supplies toner to the developing roller 61 and scrapes off the toner on the developing roller 61. 62 and a regulating member 63 that regulates the thickness of the toner on the developing roller 61 and charges the toner.

  The toner storage unit 70 is provided with an agitator 71 as a member for stirring the toner. The agitator 71 is rotationally driven by a motor (not shown) and agitates the toner in the toner storage unit 70. When the toner is agitated by the agitator 71, unevenness is eliminated and the charged state is stabilized. For example, the printer 100 drives the agitator 71 during image formation to stir the toner. The agitator 71 is an example of a stirring unit.

  A part of the agitated toner is discharged toward the developing unit 60 through the supply port 69. The toner discharged from the supply port 69 to the developing unit 60 is supplied to the developing roller 61 by the rotation of the toner supply roller 62, and at this time, the toner is frictionally charged between the toner supplying roller 62 and the developing roller 61. The toner supplied onto the developing roller 61 enters between the regulating member 63 and the developing roller 61 as the developing roller 61 rotates, and is thinned while being frictionally charged. Then, at a position facing the photoreceptor 1, a part of the toner moves onto the photoreceptor 1 and develops the electrostatic latent image formed on the photoreceptor 1.

  If stirring is not performed for a long period of time, there is a high possibility that the toner charge amount in the toner storage unit 70 is uneven. For example, in the printer 100 in which the toner container 70 is set and shipped in advance, the toner in the toner container 70 may be exposed to the outside air during the storage period after manufacture. In particular, when the storage period after manufacturing the printer 100 is long, the toner tends to aggregate. Therefore, there is a high possibility that the toner charge amount is uneven at the first operation after the main body is shipped. If printing is performed using toner with uneven charging amount, printing with low image quality may occur due to uneven density. For example, the printer 100 agitates the toner in order to reliably stabilize the charged state of the toner at the time of the first printing after the main body is shipped or after the printing is not performed for a long time.

  Returning to the description of the image forming unit 10 in FIG. 2, the surface of the photoreceptor 1 is uniformly charged by the charging device 2 in each of the process units 50C, 50M, 50Y, and 50K. Thereafter, exposure is performed with light from the exposure device 53, and an electrostatic latent image of an image to be formed is formed on the photoreceptor 1. Next, toner is supplied to the photoreceptor 1 via the developing device 4. Thereby, the electrostatic latent image on the photoreceptor 1 is visualized as a toner image.

  The image forming unit 10 takes out the sheets placed on the paper feed tray 91 one by one and conveys the sheets onto the conveyance belt 7. The toner image formed by the process unit 50 is transferred to the sheet. At this time, in color printing, toner images are formed by the process units 50C, 50M, 50Y, and 50K, and the toner images are superimposed on the sheet. On the other hand, in monochrome printing, a toner image is formed only by the process unit 50K and transferred to a sheet. Thereafter, the sheet on which the toner image is transferred is conveyed to the fixing device 8 and the toner image is thermally fixed to the sheet. Then, the sheet after fixing is discharged to a discharge tray 92.

  In addition, the printer 100 executes a correction process for acquiring correction values for correcting images so that density unevenness and positional deviation do not occur in the images formed by the process units 50C, 50M, 50Y, and 50K. Therefore, the mark sensor 25 is disposed at a position downstream of the process units 50C, 50M, 50Y, and 50K in the traveling direction of the transport belt 7 and through which the sheet does not pass. As a procedure of the correction process, a correction pattern image is formed in each of the process units 50C, 50M, 50Y, and 50K, and the pattern image is transferred onto the conveyance belt 7. Then, the printer 100 causes the mark sensor 25 to read the correction pattern image formed on the conveyance belt 7 and determines a correction value for bringing it closer to an ideal image based on the read result. The mark sensor 25 is an example of a sensor.

  Specifically, as shown in FIG. 4, the mark sensor 25 includes two sensors, a sensor 25R disposed on the right side in the width direction of the transport belt 7 and a sensor 25L disposed on the left side. Each of the sensors 25R and 25L is a reflective optical sensor in which a light emitting element 23 such as an LED and a light receiving element 24 such as a phototransistor are paired. The mark sensor 25 is configured to irradiate light from the oblique direction to the dotted frame E in FIG. 4 on the surface of the conveyor belt 7 by the light emitting element 23, and the light receiving element 24 receives the light. . The correction mark 27 can be detected by the difference between the amount of light received when the correction mark 27 passes and the amount of light received directly from the conveyor belt 7. Note that the mark 27 in FIG. 4 is an example of a pattern image for correcting misalignment.

  The printer 100 is connected to the PC 200 via the communication IF 38 and receives a print execution instruction from the PC 200. For example, as illustrated in FIG. 5, the PC 200 expands an image to be printed to generate bitmap-format expansion data, and transmits the generated expansion data to the printer 100. The printer 100 receives the development data from the PC 200 and executes printing based on the development data.

  When developing the image, the PC 200 executes various image corrections so that the print result is as close as possible to the target image. For image correction, the PC 200 requests the connected printer 100 to transmit various correction values. The printer 100 executes a process for acquiring a correction value, and transmits the acquired correction value to the connected PC 200. The PC 200 receives various correction values for each connected printer and stores them in the NVRAM 34 or the like in association with the printer. The process for acquiring the correction value will be described later.

  When receiving the print command, the PC 200 reads the correction value of the printer 100 to be printed from the NVRAM 34 or the like, and generates expanded data reflecting the image correction based on the correction value. When the correction value of the printer 100 to be printed is not stored, for example, when a new printer 100 is connected, the PC 200 requests the printer 100 to transmit the correction value before transmitting the print job. The received correction value is stored in the NVRAM 34 or the like.

  Image correction includes, for example, position shift correction, density correction, and density gradation correction. For example, when generating development data subjected to density gradation correction, the PC 200 receives and stores as a correction value a table indicating the relationship between the density gradation of the original image and the density gradation after correction. . Then, the PC 200 corrects the density value of each point of the image to be printed based on the table, and generates development data with the corrected density value. Details of each correction will be described later.

  Next, various correction processes executed by the printer 100 will be described. The printer 100 according to the present embodiment executes correction processing for acquiring correction values used for correction of misregistration, density correction, and density gradation correction. Note that these correction processes are merely examples, and the present invention is not limited to these.

  The misregistration correction is a dynamic image position misalignment caused by the eccentricity of the photosensitive member 1 or the transport roller, a shift in the pitch of the gear that rotationally drives these, a misalignment of the mounting position of the photosensitive member 1 or the exposure device 53, or the like. This is a process for acquiring a correction value for adjusting a static image position shift caused by the above. In the misalignment correction, the printer 100 forms marks 27K, 27C, 27M, and 27Y as shown in FIG. For example, the printer 100 arranges the long and narrow marks 27 side by side at the reading positions of the mark sensors 25R and 25L on both sides in the traveling direction of the transport belt 7. The printer 100 reads the mark 27 with the mark sensor 25, calculates the interval between the marks 27, and acquires the periodic positional deviation amount and the positional deviation amount between colors.

  The density correction is a process for acquiring a correction value for adjusting a deviation between a target density defined in the printer 100 and a density of an actually formed mark. In the density correction, as shown in FIG. 6, the printer 100 forms a mark 28 including, for example, 100% density marks 28K, 28C, 28M, and 28Y for each color. The printer 100 reads these marks 28 with the mark sensor 25 and acquires the density of the formed marks based on the amount of received light. Then, a correction value for making the current density close to the target density is acquired. The mark 28 is an example of a density correction pattern image.

  For example, the printer 100 approximates the relationship between the target density of the mark 28 and the density acquired based on the output of the mark sensor 25 using a linear function, and calculates image data from the difference between the current density and the target density. The adjustment amount of the value of is calculated. Then, the printer 100 acquires an adjustment amount corresponding to the target density as a correction value for density correction, and transmits it to the PC 200. The PC 200 corrects the density of the image to be printed based on the received correction value, and generates development data. When the printer 100 performs printing based on the development data received from the PC 200, the density of the image as a printing result is close to the target density.

  The printer 100 can correct the image density by correcting the development bias value and the exposure bias value, for example. That is, the correction value of the development bias value or the exposure bias value may be acquired from the difference between the target density and the density of the formed mark and transmitted to the PC 200. The PC 200 transmits a correction value to the printer 100 that executes printing, and executes correction based on the correction value before starting printing.

  The density gradation correction is, for example, gamma correction, and is a process of acquiring a correction value for correcting a deviation between an instruction density or an instruction gradation by an external computer and an output density of the printer 100 itself. In the density gradation correction, as shown in FIG. 7, the printer 100 has, for each color, for example, multiple density marks 291K, 292K, and 293K with solid images of 20%, 40%, 60%, 80%, and 100%. , 294K, and 295K. In FIG. 7, only the image of the black mark is illustrated.

  The printer 100 reads the formed mark 29 with the mark sensor 25, calculates the actual density based on the amount of received light, and acquires density data. Furthermore, the density change characteristics of each color are specified based on the relative relationship of the density of each mark. Then, as a correction value, a relative relationship table between the change characteristic and the gradation indicated by the external computer is created. The density gradation correction mark is an example of a correction pattern image.

  The printer 100 forms the density correction mark 28 and the density gradation correction mark at the reading position of either the mark sensor 25R or 25L. These marks may be formed on both sides of the mark sensors 25R and 25L. However, in order to obtain appropriate mark data while suppressing the amount of toner used, it is preferable to form these marks only on one side.

  There are a plurality of correction processing execution conditions in the printer 100 for each correction process. As execution conditions, for example, the first time after the main body is shipped, a correction value transmission request from the PC 200, cover opening and closing, replacement of the toner storage unit 70, power-on, user instruction input, printing over a predetermined number of sheets, rotation of the agitator 71 The amount is more than the threshold, the continuous startup time is more than the threshold, the environmental change such as humidity and temperature, or a combination thereof.

  The printer 100 determines whether or not the execution conditions for each correction process are satisfied. If it is determined that the execution conditions are satisfied, the printer 100 executes a correction process that satisfies the execution conditions. After executing the correction process and acquiring the correction value, the printer 100 notifies the PC 200 that the correction value is ready to be transmitted. Then, in response to receiving a correction value transmission request from the PC 200, the printer 100 transmits the acquired correction value to the PC 200.

  As described above, in the printer 100, for example, in a state where the toner is not stirred for a long time, the charged state of the toner is unstable, and there is a high possibility of density unevenness. Even if the correction processing execution condition is satisfied in this state and a correction pattern image is formed, the reliability of the pattern image itself is low. On the other hand, it is not preferable to perform agitation for a sufficient time each time the correction processing execution condition is satisfied, because the time required for the correction processing is prolonged and toner deterioration may be advanced.

  When the execution condition of the correction process is satisfied, the printer 100 determines whether there is a high possibility of density unevenness or the like and whether a highly reliable correction value is required. When the printer 100 determines that there is a high possibility of density unevenness or the like, or determines that a highly reliable correction value is required, the printer 100 forms a pattern image and Read and execute twice. For example, if the printer 100 satisfies at least one of the first condition after shipment of the main body, the first time after power-on, and the first time after the replacement of the toner container 70, the printer 100 determines that the possibility of density unevenness is high. For example, if the gamma correction execution condition is satisfied, the printer 100 determines that a highly reliable correction value is required.

  The printer 100 stirs the toner even during the pattern formation and executes the pattern formation twice. Then, the printer 100 transmits the correction value acquired based on the reading result to the PC 200 on the condition that the difference between the two reading results is within the allowable range. For example, when the execution condition of the correction process is satisfied when the toner charging state is unstable, the toner charging state changes between the first time and the second time, and the difference becomes large. This is because the agitation of the toner proceeds more than the first time and the charged state of the toner is more stable.

  That is, the printer 100 can determine whether or not a highly reliable correction value has been acquired by determining whether or not the difference between the two reading results is within an allowable range. When the difference between the reading results is large, the reliability of the correction value acquired by pattern formation is not high. On the other hand, if the difference between the reading results is not large, it can be estimated that there was no significant change between the two times, and the first and second times were almost stable. That is, it can be estimated that the charged state of the toner is good.

  Next, correction transmission processing, which is a correction value transmission operation executed by the printer 100, will be described with reference to a flowchart of FIG. The correction transmission process is executed by the CPU 31 when the execution condition of the correction process is satisfied.

  The printer 100 that executes the flowchart of FIG. 8 transmits the density gradation correction value to the PC 200 among the various correction values described above, and causes the PC 200 to execute the density gradation correction. On the other hand, the printer 100 stores the positional deviation correction value and the density correction value in its own apparatus, and executes the positional deviation correction and the density correction in its own apparatus. That is, the correction transmission process shown in FIG. 8 is a process for transmitting the correction value for density gradation correction to the PC 200.

  In the correction transmission process, the printer 100 first forms and reads the first pattern image (S101). S101 is an example of a pattern forming process and a pattern reading process. As described above, the pattern image differs depending on the type of correction processing. The printer 100 forms the mark 29 which is the density gradation correction pattern image shown in FIG. 7 on the conveyance belt 7 and acquires the read result of the formed pattern image based on the output signal of the mark sensor 25. The read result is the density of the mark 29 for each color and density.

  Next, the printer 100 starts generating a correction value based on the pattern image reading result (S102). S102 is an example of a generation process. Since the correction value generated in S102 is a correction value based on the first pattern image, it is set as the first correction value.

  Next, the printer 100 receives a correction value transmission instruction from the PC 200 as an execution condition of the correction process, and determines whether the transmission instruction is based on a monochrome image printing instruction (S103). That is, it is determined whether or not a notification is received from the PC 200 that a monochrome image print job is to be transmitted after the correction value is received.

  Then, in response to the determination that the printer 100 is based on the monochrome image printing instruction (S103: YES), the printer 100 transmits the first correction value started to be generated in S102 to the PC 200 (S104). S104 is an example of an early transmission process. That is, when the printer 100 receives a correction value transmission instruction from the PC 200 after the first pattern image formation or reading is completed and before the second pattern image formation or reading is started. Transmits a correction value based on the first pattern image reading result.

  In particular, when it is determined that the correction value transmission instruction received from the PC 200 is based on the printing instruction, priority is given to the early termination of printing over the correction accuracy. For example, in a monochrome character image, the printing density is often 0% or 100%, and it is estimated that the possibility of using a halftone is small. That is, there is a high possibility that a correction value for density gradation correction, which is density adjustment including an intermediate gradation, is not necessary. Further, if the printing instruction is monochrome printing, no correction for misregistration between colors is necessary. Therefore, when the printer 100 receives a correction value transmission instruction based on a monochrome printing instruction, the printer 100 transmits a first correction value after a process for improving the reliability of the correction value.

  On the other hand, if the printer 100 determines that it is not based on a monochrome image printing instruction (S103: NO), it does not transmit the first correction value. For example, since color shift and density gradation shift are easily noticeable in a color image, the printer 100 acquires a highly reliable correction value and transmits it when based on a print instruction for a color image. If the transmission instruction is not based on the print instruction, the urgency is low, and the printer 100 transmits the correction value after obtaining a highly reliable correction value. That is, the printer 100 does not execute the early transmission process when the transmission instruction is not based on the monochrome image printing instruction.

  Next, the printer 100 executes the second pattern image formation and reading (S106). S106 is also an example of pattern formation processing and pattern reading processing. In S106, the same shape and the same number of pattern images are formed under the same formation conditions as in S101. That is, in S106, for example, the charging bias value, the developing bias value, and the exposure intensity are set to the same values as in S101, and the mark 29 is formed again.

  Furthermore, the printer 100 starts generating correction values based on the second reading result (S107). S107 is also an example of the generation process. Since the correction value generated in S107 is a correction value based on the second pattern image, it is set as the second correction value. In addition, as a start timing of S106, S101 should just be complete | finished and S102 and S104 may be in execution.

  Then, the printer 100 calculates the difference between the first correction value generated in S102 and the second correction value generated in S107 for each color and density, and determines whether each difference is large. (S109). S109 is an example of a determination process. For example, the printer 100 determines whether or not a difference calculated for each color and density is larger than a corresponding difference threshold value determined in advance. Specifically, for example, the printer 100 calculates a difference between a first correction value of black 20% density and a second correction value of black 20% density, and uses the calculated difference as a difference threshold value of black 20% density. Compare with For example, the printer 100 calculates a difference between a first correction value of 40% density of yellow and a second correction value of 40% density of yellow, and compares the calculated difference with a difference threshold value of 40% density of yellow. To do.

  That is, the printer 100 generates the first correction value and the second correction value for each color, each density, or each color combination. In S109, the difference and the difference threshold value are calculated for each color, each density, or each color combination. Compare. The difference threshold is prepared for each color, each density, or each color combination, and may be a different value for each color, each density, or each color combination.

  In response to determining that at least one of the differences for each color and density is large (S109: YES), the printer 100 executes pattern image formation and reading again (S111). In S111, only a pattern image having a color or density determined to have a large difference may be formed. For example, if the difference between the first correction value for black 20% density and the second correction value for black 20% density is larger than the difference threshold value for black 20% density, the printer can be used even if other differences are not large. 100 is determined as YES in S109. In step S <b> 111, the printer 100 forms a mark 291 </ b> K which is a black 20% density mark among the marks 29. The printer 100 does not form marks with colors and densities that do not differ greatly.

  For colors and densities with small differences, the printer 100 employs the first correction value or the second correction value as a highly reliable correction value. In addition, the printer 100 can save only the amount of toner used and the time required to acquire the correction value by forming only a pattern image having a large difference.

  Then, the printer 100 starts generating a correction value based on the reading result of S111 (S112). When the generation of the correction value is completed, the printer 100 returns to S109 and compares it with the previous correction value to determine whether or not the difference is large. For example, in the above-described example, the printer 100 has formed and read the mark 291K which is the black 20% density mark of the mark 29, so in S112, based on the read result, the black 20% density black. Only the correction value is generated. In step S109, the printer 100 corrects the black 20% density correction value of the black 20% density generated in step S112 and the second correction value which is the previous correction value generated in step S107. And compare.

  On the other hand, in response to determining that the difference is not large (S109: NO), the printer 100 transmits the last correction value to the PC 200 (S114). S114 is an example of a transmission process. The correction value transmitted to the PC 200 is an example of transmission target data. The last correction value is the most recently generated correction value. For example, if it is determined in S109 that the difference between the first correction value and the second correction value is not large, the printer 100 transmits the second correction value in S114.

  On the other hand, as in the above-described example, it is determined that the difference between the first correction value and the second correction value of the 20% density of black is large, and the mark 291K is additionally formed and read, and generated from the read result. When it is determined that the difference between the additional correction value of the black 20% density and the second correction value is not large, the printer 100 transmits the additional correction value as the correction value of the black 20% density. The printer 100 transmits a second correction value as a correction value for a color or density other than the 20% density of black.

  If it is determined in S109 that the difference between the additional correction value and the second correction value is large (S109: YES), the printer 100 again executes mark formation, reading, and generation of a correction value ( S111, S112). Then, the printer 100 compares the additional correction value generated again in step S112 with the previous additional correction value. As a result, when it is determined that the difference is not large, the printer 100 transmits the additional correction value again to the PC 200.

  Note that the printer 100 may notify the PC 200 that the correction value is ready in S114, and transmit the correction value after receiving a transmission request from the PC 200. When the transmission of the correction value is completed, the printer 100 ends the correction transmission process.

  As described above in detail, the printer 100 of this embodiment performs pattern image formation and reading twice, and the difference in data regarding the pattern image reading results between the first time and the second time is within an allowable range. Judge whether there is. Then, when it is determined that the difference is within the allowable range, data based on at least one of the first time and the second time is transmitted to the PC 200. If the charged state of the toner is unstable, the difference between the first time and the second time tends to be large, and if the difference is small, it can be estimated that the charged state of the toner is good. That is, when the printer 100 determines that a highly reliable correction value has been obtained, the printer 100 transmits data related to the pattern image reading result, and thus corrects the image to be printed using the data related to the pattern image reading result. In the system, deterioration in image quality can be suppressed.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, the present invention is not limited to a printer, and can be applied to any apparatus having an image forming function, such as a copying machine, a multifunction machine, and a FAX apparatus.

  In this embodiment, the correction value is generated by the printer 100. However, the correction value can also be generated by the PC 200. For example, the printer 100 may determine whether or not the difference in the output signal of the mark sensor 25 or the difference in the density data based on the output signal of the mark sensor 25 is large in S109. If it is determined that the difference is not large, the printer 100 may transmit the output signal of the mark sensor 25 or the density data based on the output signal of the mark sensor 25 to the PC 200. The PC 200 may generate and store a correction value from the received data.

  Further, for example, the PC 200 may determine whether or not the difference in S109 is large. For example, as shown in FIG. 9, the printer 100 may transmit the pattern image reading results for two times to the PC 200 and cause the PC 200 to calculate the difference. For example, the printer 100 executes formation and reading of a pattern image (S201), and transmits the reading result to the PC 200 (S202). The PC 200 receives the reading result from the printer 100 (S301), and generates a first correction value (S302). Similarly, the second time is also performed (S203, S204, S303, S304). Furthermore, the PC 200 determines whether or not the difference between the first correction value and the second correction value is large (S305). If it is determined that the difference is large (S305: YES), the PC 200 requests the printer 100 to retransmit the reading result (S306). The printer 100 receives the re-transmission request (S205), executes the formation and reading of the pattern image again (S206), transmits the additional reading result to the PC 200 (S207), and ends. If there is no re-transmission request, the printer 100 ends the process after S204. Further, after S207, if re-transmission is requested, the printer 100 may repeat S205 to S207. The PC 200 receives the additional reading result (S307), and generates an additional correction value (S308). If it is determined that the difference between the correction values is not large (S305: NO), the last correction value is stored in the hard disk or the like (S309), and the process is terminated.

  Alternatively, the printer 100 may execute up to the calculation of the difference, transmit the calculated difference to the PC 200, and determine whether the difference is large or not in the PC 200. That is, S202, S204, S301, and S303 in FIG. 9 may be deleted, and the printer 100 may execute until the calculation of the difference among S302, S304, and S305.

  Further, the data to be transmitted when the difference between the two reading results is small is not limited to the latest correction value. For example, the printer 100 may transmit the first correction value, or may transmit an average value or an intermediate value obtained from the first correction value and the second correction value.

  Further, the pattern image is formed once again in response to the determination that the difference is large. However, the pattern image may not be formed and may end with an error. Further, for example, if the difference does not become small even after repeating pattern formation a predetermined number of times, the process may end with an error.

  In this embodiment, the first correction value is transmitted when an instruction to print a monochrome image is received. However, the first correction value may not be transmitted. For example, as shown in the flowchart of FIG. 10, it is not necessary to determine whether or not there is a print instruction. That is, regardless of whether or not a print instruction is accepted, the pattern image may be formed and read twice, and the difference may be confirmed. When the first correction value is transmitted in response to a monochrome image printing instruction, only the K color correction value necessary for the monochrome image correction may be transmitted.

  In this embodiment, when it is determined that the difference is large, only the pattern image having the color or density determined to have a large difference is formed. However, patterns of all colors may be formed. If only colors having a large difference are formed, the amount of toner used can be suppressed. On the other hand, if all color patterns are formed, a more accurate correction value can be acquired.

  In this embodiment, the positional deviation correction value and the density correction value are stored in the printer 100. However, the positional deviation correction value and the density correction value may be transmitted to the PC 200. In that case, the printer 100 forms a pattern image corresponding to each correction, reads the pattern image, and acquires a reading result. The reading result is, for example, a relative position for each color combination in the positional deviation correction, and a density of the pattern image for each color in the density correction. For example, the PC 200 may transmit the positional deviation correction value and the density correction value to the printer 100 prior to transmission of the image data, and may cause the printer 100 to adjust the image formation start timing and the bias voltage value. In addition, the printer 100 may transmit at least one of the positional deviation correction value and the density correction value to the PC 200 and store the density gradation correction value in the printer 100.

  In this embodiment, the pattern formation and reading are performed twice. However, the printer 100 has a low possibility of density unevenness and the like, and a correction value with particularly high reliability is not required. , Pattern formation and reading only once may be executed. Then, the printer 100 may transmit data based on one reading result to the PC 200. By forming the pattern once, it is possible to save the amount of toner used and the time required to acquire the correction value.

  The processing disclosed in the embodiments may be executed by a single CPU, a plurality of CPUs, hardware such as an ASIC, or a combination thereof. Further, the processing disclosed in the embodiment can be realized in various modes such as a recording medium or a method recording a program for executing the processing.

10 Image forming unit 25 Sensor 31 CPU
70 Toner container 71 Agitator 100 Printer

Claims (12)

An image forming unit for forming an image;
A sensor,
A control unit;
With
The controller is
A pattern forming process for forming a correction pattern image in the image forming unit;
A pattern reading process for causing the sensor to read the pattern image formed in the pattern forming process;
Data relating to a reading result obtained by reading the pattern image formed in the first pattern forming process in the first pattern reading process, and a pattern image formed in the second pattern forming process are used as the second pattern. A determination process for determining whether or not a difference from data relating to a reading result read in the reading process is within an allowable range;
Data relating to at least one of a reading result of the first pattern reading process and a reading result of the second pattern reading process in response to determining that the difference is within the allowable range in the determination process. A transmission process for transmitting data to be transmitted to an external device;
An image forming apparatus characterized in that The image forming apparatus according to claim 1,
A container for containing toner;
An agitation unit for agitating the toner contained in the container;
With
The image forming unit forms an image using toner stored in the container;
At the time of forming a pattern image in the pattern forming process, the toner is stirred in the stirring unit,
The controller is
In the transmission process, the image forming apparatus transmits data related to a reading result of the second pattern reading process to the external apparatus. The image forming apparatus according to claim 1, wherein:
The controller is
When the transmission instruction of the transmission target data is received before the transmission of the transmission target data is started in the transmission process after the first pattern reading process is completed, the first reading of the pattern reading process is performed. An image forming apparatus, wherein an early transmission process for transmitting data relating to a result to the external apparatus is executed. The image forming apparatus according to claim 3,
The controller is
The image forming apparatus, wherein the early transmission process is executed when the received transmission instruction is a transmission instruction based on a monochrome image printing instruction. In the image forming apparatus according to any one of claims 1 to 4,
The controller is
Executing a generation process for generating correction data based on a reading result in the pattern reading process;
In the transmission process, data relating to at least one of the correction data generated based on the reading result of the first pattern reading process and the correction data generated based on the reading result of the second pattern reading process Is the transmission target data. The image forming apparatus according to claim 5,
The controller is
An image forming apparatus comprising: starting the generation process based on the first pattern reading process before the second pattern reading process is completed. The image forming apparatus according to any one of claims 1 to 6,
The controller is
In the pattern forming process, the pattern image relating to a plurality of density gradations is formed in the image forming unit,
In the determination process, it is determined whether or not the difference is within an allowable range for each density gradation, and when there is a density gradation outside the allowable range in at least one of the plurality of density gradations, An image forming apparatus, wherein the image forming apparatus is determined to be outside the allowable range. In the image forming apparatus according to any one of claims 1 to 7,
The controller is
When it is determined in the determination process that the difference is outside the allowable range, the pattern formation process and the pattern reading process are executed again, and the pattern image formed in the previous pattern formation process is changed to the pattern Whether the difference between the data relating to the reading result read in the reading process and the data relating to the reading result obtained by reading the pattern image formed in the current pattern forming process in the pattern reading process is within an allowable range. An image forming apparatus characterized by The image forming apparatus according to claim 8,
A different image forming unit for each toner color;
In the pattern forming process, the pattern image is formed for each color,
The controller is
In the determination process, it is determined whether the difference is within an allowable range for each color or each combination of colors;
When there is a color for which the difference is determined to be outside the allowable range or a combination of colors for which the difference is determined to be out of the allowable range, the pattern forming process to be executed again is out of the allowable range. An image forming apparatus, wherein the pattern image is formed for a color or a combination of colors determined to be. In the image forming apparatus according to any one of claims 1 to 8,
A different image forming unit for each toner color;
The controller is
In the determination process, it is determined whether the difference is within an allowable range for each color or each combination of colors;
In the determination process, if there is at least one color out of the allowable range or a combination of colors out of the allowable range among a plurality of colors or color combinations, it is determined that the color is out of the allowable range. An image forming apparatus. In a system comprising an image forming apparatus for forming an image and an external device connected to the image forming apparatus,
A pattern forming step for causing the image forming apparatus to form a correction pattern image;
A pattern reading step for reading the pattern image formed in the pattern forming step;
The data relating to the reading result obtained by reading the pattern image formed in the first pattern forming step in the first pattern reading step and the pattern image formed in the second pattern forming step are used in the second time. A difference determining step for determining whether or not a difference from the data related to the reading result read in the pattern reading step is within an allowable range;
In response to determining that the difference is within the allowable range in the difference determination step, at least one of a reading result by the first pattern reading step and a reading result by the second pattern reading step. An acquisition step for causing the external device to acquire correction data based on the data;
An image forming step of causing the image forming apparatus to form an image corrected by the external device based on the correction data;
An image forming method comprising: An image forming unit for forming an image;
A sensor,
In an image forming apparatus comprising
A pattern forming process for forming a correction pattern image in the image forming unit;
A pattern reading process for causing the sensor to read the pattern image formed in the pattern forming process;
Data relating to a reading result obtained by reading the pattern image formed in the first pattern forming process in the first pattern reading process, and a pattern image formed in the second pattern forming process are used as the second pattern. A determination process for determining whether or not a difference from the data relating to the reading result read in the reading process is within an allowable range;
Data relating to at least one of a reading result of the first pattern reading process and a reading result of the second pattern reading process in response to determining that the difference is within the allowable range in the determination process. A transmission process for transmitting data to be transmitted to an external device;
A program characterized by having executed.

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