JP6369254B2 - Printing device - Google Patents

Description

  The present invention relates to a printing apparatus that calibrates and updates tone correction data for tone correction of print data.

  In order to maintain gradation reproducibility and the like, the printing apparatus executes calibration at the start of printing or every time a certain number of sheets are printed. Calibration is a process for generating and updating gradation correction data and the like from measurement data obtained by forming an image of a patch on a transfer belt and optically reading the patch.

  When calibration is executed, a patch image is formed, so that resources such as toner are consumed, and execution of the original printing process is delayed by the amount of calibration.

  Patent Document 1 below provides full calibration and simple calibration with shorter resource consumption and processing time than the full calibration, and the type of image data to be printed (image, graphic, text, color / monochrome). ) To select which calibration to execute or switch the calibration execution interval, thereby reducing the consumption of resources and the delay in print processing associated with the execution of calibration. Is disclosed.

JP 2005-181534 A

  In Patent Document 1, it is selected whether to perform simple calibration or full calibration depending on the type of image data to be printed. For this reason, as the number of types of image data that require full calibration increases, the number of full calibrations increases, resulting in an increase in toner consumption and delay in print processing. On the other hand, even if simple calibration is performed instead of full calibration at a scene where full calibration is to be performed, appropriate correction cannot be performed.

  The present invention is intended to solve the above-described problem, and a printing apparatus capable of ensuring gradation correction with a required accuracy while reducing consumption of toner and delay in printing processing due to calibration. The purpose is to provide.

  The gist of the present invention for achieving the object lies in the inventions of the following items.

[1] a gradation correction unit that performs gradation correction of print data;
A printing unit that prints based on print data that has undergone gradation correction by the gradation correction unit;
A holding unit for holding first-type gradation correction data used by the gradation correction unit for gradation correction;
A reading unit for optically reading an image formed by the printing unit;
A first calibration execution unit that performs a first calibration for generating first-gradation correction data from measurement data obtained by forming an image of a patch on the printing unit and optically reading the patch by the reading unit When,
A second calibration execution unit that performs a second calibration for generating second-type gradation correction data from measurement data obtained by causing the printing unit to form a patch image and optically reading the patch by the reading unit. When,
An estimated value deriving unit for deriving an estimated value of the first type gradation correction data based on the second type gradation correction data;
When updating the first type gradation correction data held in the holding unit, it is determined whether to use the first calibration execution unit or the estimated value derivation unit, and the first calibration execution is performed. The first-type gradation correction data held in the holding unit is updated with the first-type gradation correction data obtained by causing the first calibration execution unit to execute the first calibration. When using the estimated value deriving unit, a control unit that updates the first-type gradation correction data held in the holding unit with the estimated value obtained by deriving the estimated value deriving unit;
I have a,
The first type gradation correction data is gradation correction data used when printing at the first resolution,
The second type gradation correction data is gradation correction data used when printing at a second resolution lower than the first resolution,
In the determination, the control unit selects use of the first calibration execution unit when the print mode is set to image quality priority, and the estimated value when the print mode is set to speed priority. A printing apparatus characterized by selecting use of a deriving unit .

  In the above invention, when the first-type gradation correction data is updated, the first calibration for actually forming the patch image is executed and updated, or the first calibration is already obtained by the second calibration for actually forming the patch image. The estimated value of the first type gradation correction data can be derived from the second type gradation correction data and updated with the estimated value.

  In the above invention, the first type gradation correction data is gradation correction data for high resolution used when printing at high resolution, and the second type gradation correction data is used when printing at low resolution. This is gradation correction data for low resolution. The first calibration execution unit executes calibration for high resolution to generate gradation correction data for high resolution, and the second calibration execution unit executes calibration for low resolution and performs gradation for low resolution. Generate correction data. The estimation deriving unit derives an estimated value of the high-resolution gradation correction data based on the low-resolution gradation correction data.

  In the above invention, in the case of image quality priority, first calibration for actually forming a patch image is executed to obtain gradation correction data, and in the case of speed priority, an estimated value is substituted.

[ 2 ] The control unit performs the update when receiving an instruction to print at the first resolution and when a predetermined weighting condition based on a printing history at the first resolution is satisfied. [ 1] The printing apparatus according to [ 1] .

  In the above invention, the weighting condition is that a certain number of prints at the first resolution have been performed or a certain amount of time has elapsed since the previous execution of the first calibration.

[3] a gradation correction unit that performs gradation correction of print data;
A printing unit that prints based on print data that has undergone gradation correction by the gradation correction unit;
A holding unit for holding first-type gradation correction data used by the gradation correction unit for gradation correction;
A reading unit for optically reading an image formed by the printing unit;
A first calibration execution unit that performs a first calibration for generating first-gradation correction data from measurement data obtained by forming an image of a patch on the printing unit and optically reading the patch by the reading unit When,
A second calibration execution unit that performs a second calibration for generating second-type gradation correction data from measurement data obtained by causing the printing unit to form a patch image and optically reading the patch by the reading unit. When,
An estimated value deriving unit for deriving an estimated value of the first type gradation correction data based on the second type gradation correction data;
When updating the first type gradation correction data held in the holding unit, it is determined whether to use the first calibration execution unit or the estimated value derivation unit, and the first calibration execution is performed. The first-type gradation correction data held in the holding unit is updated with the first-type gradation correction data obtained by causing the first calibration execution unit to execute the first calibration. When using the estimated value deriving unit, a control unit that updates the first-type gradation correction data held in the holding unit with the estimated value obtained by deriving the estimated value deriving unit;
Have
Wherein the control unit, the difference between the current second Tanekaicho correction data obtained by the second Tanekaicho correction data and the second calibration of the preceding obtained by the second calibration or, in this the When the difference between the measurement data obtained by optically reading the patch in the second calibration and the measurement data obtained by optically reading the patch in the previous second calibration is equal to or greater than the first threshold, The determination is made by determining that the first-type gradation correction data held in the holding unit needs to be updated. In the determination, if the difference is greater than the first threshold and less than the second threshold the choose to use the estimated value derivation section, if the difference is greater than the second threshold value printing device you and selects the use of the first calibration execution unit.

  In the above-described invention, the first calibration execution unit is used for updating the first-type gradation correction data or the estimated value deriving unit is used based on the magnitude of the difference between the execution results of the second calibration and the previous second calibration. To decide.

Et al is based on the difference, to determine the necessity of updating the first Tanekaicho correction data. That is, when “difference> second threshold”, the first calibration execution unit is used, and when “second threshold ≧ difference> first threshold”, the estimation derivation unit is used, and “first threshold ≧ difference”. In this case, the first type gradation correction data is not updated.

[4] a gradation correction unit that performs gradation correction of print data;
A printing unit that prints based on print data that has undergone gradation correction by the gradation correction unit;
A holding unit for holding first-type gradation correction data used by the gradation correction unit for gradation correction;
A reading unit for optically reading an image formed by the printing unit;
A first calibration execution unit that performs a first calibration for generating first-gradation correction data from measurement data obtained by forming an image of a patch on the printing unit and optically reading the patch by the reading unit When,
A second calibration execution unit that performs a second calibration for generating second-type gradation correction data from measurement data obtained by causing the printing unit to form a patch image and optically reading the patch by the reading unit. When,
An estimated value deriving unit for deriving an estimated value of the first type gradation correction data based on the second type gradation correction data;
When updating the first type gradation correction data held in the holding unit, it is determined whether to use the first calibration execution unit or the estimated value derivation unit, and the first calibration execution is performed. The first-type gradation correction data held in the holding unit is updated with the first-type gradation correction data obtained by causing the first calibration execution unit to execute the first calibration. When using the estimated value deriving unit, a control unit that updates the first-type gradation correction data held in the holding unit with the estimated value obtained by deriving the estimated value deriving unit;
Have
Wherein, based on the execution count of the second calibration is performed after the last execution of the first calibration, printing device you and performing the determination.

In the above invention, based on the number of executions of the second calibration executed after the previous execution of the first calibration, whether to use the first calibration execution unit for updating the first type gradation correction data is derived. Decide whether to use parts.

[ 5 ] When the number of executions is equal to or greater than a third threshold, the control unit determines that the first-type gradation correction data held in the holding unit needs to be updated, makes the determination, and In the determination, if the number of executions is greater than the third threshold and less than a fourth threshold, use of the estimated value deriving unit is selected, and if the number of executions is equal to or greater than the fourth threshold, the first calibration is performed. The printing apparatus according to [ 4 ], wherein the use of a copy is selected.

In the above invention, in addition to the invention of [ 4 ], whether or not the first-type gradation correction data needs to be updated based on the number of executions of the second calibration executed after the previous execution of the first calibration. Judging. That is, when “the number of executions> the fourth threshold”, the first calibration execution unit is used, and when “the fourth threshold ≧ the number of executions> the third threshold”, the estimation derivation unit is used, and “the third threshold ≧ In the case of “execution count”, the first-type gradation correction data is not updated.

[ 6 ] A gradation correction unit that performs gradation correction of print data;
A printing unit that prints based on print data that has undergone gradation correction by the gradation correction unit;
A holding unit for holding first-type gradation correction data used by the gradation correction unit for gradation correction;
A reading unit for optically reading an image formed by the printing unit;
A first calibration execution unit that performs a first calibration for generating first-gradation correction data from measurement data obtained by forming an image of a patch on the printing unit and optically reading the patch by the reading unit When,
A second calibration execution unit that performs a second calibration for generating second-type gradation correction data from measurement data obtained by causing the printing unit to form a patch image and optically reading the patch by the reading unit. When,
An estimated value deriving unit for deriving an estimated value of the first type gradation correction data based on the second type gradation correction data;
When updating the first type gradation correction data held in the holding unit, it is determined whether to use the first calibration execution unit or the estimated value derivation unit, and the first calibration execution is performed. The first-type gradation correction data held in the holding unit is updated with the first-type gradation correction data obtained by causing the first calibration execution unit to execute the first calibration. When using the estimated value deriving unit, a control unit that updates the first-type gradation correction data held in the holding unit with the estimated value obtained by deriving the estimated value deriving unit;
Have
Wherein, when the number of executions of the second calibration is performed after the last execution of the first calibration is larger than a predetermined number of times, to execute the first calibration in the first calibration execution unit obtained was first Tanekaicho correction data in printing apparatus you and updates the first Tanekaicho correction data held in the holding unit.

  In the above invention, when the number of executions of the second calibration executed after the recent execution of the first calibration is greater than the predetermined number, the first calibration is executed and the first-type gradation correction data is updated.

[7] A gradation correction unit that performs gradation correction of print data;
A printing unit that prints based on print data that has undergone gradation correction by the gradation correction unit;
A holding unit for holding first-type gradation correction data used by the gradation correction unit for gradation correction;
A reading unit for optically reading an image formed by the printing unit;
A first calibration execution unit that performs a first calibration for generating first-gradation correction data from measurement data obtained by forming an image of a patch on the printing unit and optically reading the patch by the reading unit When,
A second calibration execution unit that performs a second calibration for generating second-type gradation correction data from measurement data obtained by causing the printing unit to form a patch image and optically reading the patch by the reading unit. When,
An estimated value deriving unit for deriving an estimated value of the first type gradation correction data based on the second type gradation correction data;
When updating the first type gradation correction data held in the holding unit, it is determined whether to use the first calibration execution unit or the estimated value derivation unit, and the first calibration execution is performed. The first-type gradation correction data held in the holding unit is updated with the first-type gradation correction data obtained by causing the first calibration execution unit to execute the first calibration. When using the estimated value deriving unit, a control unit that updates the first-type gradation correction data held in the holding unit with the estimated value obtained by deriving the estimated value deriving unit;
Have
When the second calibration execution interval is equal to or greater than the fifth threshold, the control unit determines that the first-type gradation correction data held in the holding unit needs to be updated and performs the determination. In the determination, if the execution interval is greater than the fifth threshold and less than the sixth threshold, the use of the estimated value deriving unit is selected, and if the execution interval is greater than or equal to the sixth threshold, the first calibration is performed. printing apparatus you and selects the use of Deployment execution unit.

In the above invention, whether to use the first calibration execution unit or the estimated value deriving unit for updating the first type gradation correction data is determined based on the execution interval of the second calibration. Further, it is determined whether or not it is necessary to update the first-type gradation correction data based on the execution interval of the second calibration. That is, when “execution interval> sixth threshold”, the first calibration execution unit is used, and when “sixth threshold ≧ execution interval> fifth threshold”, the estimation derivation unit is used, and “fifth threshold ≧ In the case of “execution interval”, the first-type gradation correction data is not updated.

[8] The first type gradation correction data is gradation correction data used when printing at the first resolution.
  The second type gradation correction data is gradation correction data used when printing at a second resolution lower than the first resolution.
  The printing apparatus according to any one of [3] to [7], wherein:

In the above invention , the first type gradation correction data is gradation correction data for high resolution used when printing at high resolution, and the second type gradation correction data is used when printing at low resolution. This is gradation correction data for low resolution. The first calibration execution unit executes calibration for high resolution to generate gradation correction data for high resolution, and the second calibration execution unit executes calibration for low resolution and performs gradation for low resolution. Generate correction data. The estimation deriving unit derives an estimated value of the high-resolution gradation correction data based on the low-resolution gradation correction data.

  According to the printing apparatus according to the present invention, it is possible to ensure the necessary system gradation correction while reducing the toner consumption and the delay of the printing process due to the calibration.

1 is a diagram illustrating an outline of a mechanical configuration of a printing apparatus according to an embodiment of the present invention. 1 is a block diagram showing a schematic configuration of a printing apparatus according to an embodiment of the present invention. 6 is a flowchart showing processing when high-resolution correction data is updated due to a print request at high resolution. When updating the high-resolution gradation correction data according to the difference between the low-resolution gradation correction data obtained by the current low-resolution calibration and the low-resolution gradation correction data obtained by the previous low-resolution calibration It is a flowchart which shows the process of. It is a flowchart which shows the process in the case of updating the gradation correction data for high resolution according to the frequency | count of implementation of low resolution calibration. It is a flowchart which shows the process in the case of updating the gradation correction data for high resolution according to the elapsed time from the last low resolution calibration.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing an outline of a mechanical configuration of a printing apparatus 10 according to an embodiment of the present invention. The printing apparatus 10 is an apparatus that forms and outputs an image based on print data received from a client PC or the like via a network or the like on a sheet.

  The printing apparatus 10 can perform color printing, and employs a so-called tandem system as a color image forming system. The printing apparatus 10 includes an intermediate transfer belt 11 having a predetermined width that is looped endlessly, and yellow (Y), magenta (M), and cyan (color) that form a single color toner image on the intermediate transfer belt 11. C) Four image forming units 12Y, 12M, 12C, and 12K for each color of black (K), a sheet feeding unit 13 that feeds sheets, a conveyance unit 14 that conveys fed sheets, a fixing device 15 and the like It is configured with.

  The image forming units 12Y, 12M, 12C, and 12K are different in the color of toner used, but have the same structure. The image forming units 12Y, 12M, 12C, and 12K have a cylindrical photosensitive drum 16 as an electrostatic latent image carrier on which an electrostatic latent image is formed, and a charging device, a developing device, A transfer device, a cleaning device, and the like are arranged and provided. A laser unit 17 including a laser diode, a polygon mirror, various lenses, a mirror, and the like is provided.

  In each of the image forming units 12Y, 12M, 12C, and 12K, the photosensitive drum 16 is driven by a driving unit (not shown) to rotate in a certain direction, and the charging device uniformly charges the photosensitive drum 16, and the laser unit 17 Forms an electrostatic latent image on the surface of the photosensitive drum 16 by scanning the photosensitive drum 16 with laser light turned on / off according to the image data of the corresponding color. The developing device visualizes the electrostatic latent image on the photosensitive drum 16 with toner. The toner image formed on the surface of the photosensitive drum 16 is transferred to the intermediate transfer belt 11 at a location where it contacts the intermediate transfer belt 11. The cleaning device removes and collects the toner remaining on the surface of the photosensitive drum 16 after the transfer by rubbing with a blade or the like.

  The intermediate transfer belt 11 is wound around a plurality of rollers and circulates in the direction of arrow A in the figure. In the process of turning, images (toner images) of each color in the order of Y, M, C, and K are formed on the intermediate transfer belt 11 by the image forming units 12Y, 12M, 12C, and 12K, and a color image is synthesized. Is done. This color image is transferred from the intermediate transfer belt 11 to the sheet at the secondary transfer position D. A density sensor 18 for reading a patch formed on the intermediate transfer belt 11 is provided immediately before the secondary transfer position D in the circumferential direction of the intermediate transfer belt 11.

  The paper feed unit 13 has a plurality of paper feed trays 13a for storing papers used for image formation, and feeds the papers one by one from the selected paper feed trays 13a toward the transport unit 14. The transport unit 14 serves to transport the paper fed out from the paper feed tray 13a, pass through the secondary transfer position D and the fixing device 15, and discharge the paper to the paper discharge tray. The conveyance unit 14 includes a conveyance roller and a guide that configure a conveyance path, and a motor that drives the conveyance roller.

  The printing apparatus 10 can print at a plurality of types of resolutions. Specifically, printing at 600 dpi (Dot Per Inch) and printing at 1200 dpi are possible. The print mode includes speed priority and image quality priority. In the speed priority mode, the time (first print time) from when the print instruction is received until the printing of the first sheet is completed is shorter than in the case of image quality priority. On the other hand, with image quality priority, higher quality printing is performed than with speed priority.

  The printing apparatus 10 cancels gradation characteristic variations caused by individual differences among apparatuses, temperature, humidity, the number of printed sheets, and the like, and ensures gradation reproducibility in a printed image. Is corrected with tone correction data, and an image is printed using the corrected print data.

  The printing apparatus 10 generates gradation correction data by performing calibration or estimation calibration. The calibration is a process for forming an image of a patch on the intermediate transfer belt 11, reading the density of the patch with the density sensor 18, and generating gradation correction data based on the measurement data of the read result. The patch is formed for each screen type and each gradation. Instead of the intermediate transfer belt 11, a configuration in which a patch image is formed on a sheet and the density is read by a sensor may be used.

  The gradation correction data is prepared for each printing resolution. The printing apparatus 10 uses high-resolution gradation correction data (first-type gradation correction data) when printing at 1200 dpi, and low-resolution gradation correction data (second-type data when printing at 600 dpi. (Tone correction data) is used. The high-resolution gradation correction data is generated by performing high-resolution calibration, or an estimated value of the high-resolution gradation correction data is generated by estimation calibration. The low-resolution gradation correction data is generated by performing low-resolution calibration.

  Estimated calibration is based on low resolution tone correction data obtained by low resolution calibration or measurement data obtained by reading a patch when performing low resolution calibration. This is a process obtained by calculation.

  The timing for updating the high-resolution gradation correction data by the high-resolution calibration or the estimation calibration is 1200 dpi from the previous update when executing the first 1200 dpi print job after starting the printing apparatus 10 (immediately before printing). When a certain number of sheets are printed, when a certain period of time has passed since the last update, or when an execution request is received from the print engine. The first control unit 21 and the second control unit 27 (see FIG. 2) check for events related to the arrival of the timing for updating the high-resolution gradation correction data, and the high-resolution gradation correction data is updated. When the timing has arrived, the first control unit 21 or the second control unit 27 generates a high-resolution calibration request.

  When updating the high-resolution gradation correction data, the printing apparatus 10 updates the high-resolution gradation correction data generated by performing the high-resolution calibration or performs high-resolution gradation correction by estimation calibration. An estimated value of data is obtained, and whether to update with the estimated value is determined based on the print mode (speed priority, image quality priority), calibration execution history, and the like, and updated by the determined method.

  The low resolution calibration is performed when a certain time has elapsed since the previous low resolution calibration was performed, or when a certain number of sheets have been printed since the previous low resolution calibration was performed, when the machine is started, or when the print engine requests Such as when receiving. The first control unit 21 and the second control unit 27 check the events related to the arrival of the timing for updating the low-resolution gradation correction data, and the first control is performed when the execution timing of the low-resolution calibration has arrived. The execution request for the low resolution calibration is generated by the unit 21 or the second control unit 27.

  FIG. 2 is a block diagram illustrating a schematic configuration of the printing apparatus 10. The drawing also shows a client PC 5 that transmits print data to the printing apparatus 10.

  The client PC 5 includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a hard disk device, a display device such as a liquid crystal display, an input device such as a keyboard / mouse, a printing device 10 and an external device. A transmission / reception I / F unit 6 for transmitting / receiving various data is provided. Various functions as the client PC 5 are realized by the CPU of the client PC 5 executing programs stored in the hard disk device or the ROM. For example, the function of the print data generation processing unit 7 is realized by the CPU of the client PC 5 executing a print driver program stored in the hard disk device.

  The print data generation processing unit 7 functions to generate print data from image data and text data. The generated print data is transmitted from the transmission / reception I / F unit 6 to the printing apparatus 10.

  The user can select and set the print resolution and print mode on the print driver setting screen. As for resolution, there are options of low resolution (600 dpi: default value) and high resolution (1200 dpi), and there are options of speed priority and image quality priority for the print mode.

  When generating the print data, the print data generation processing unit 7 adds a print parameter indicating the print resolution and the print mode (speed priority / image quality priority) set by the print driver to the print data. Note that the printing apparatus 10 may hold setting values such as resolution and print mode.

  The printing apparatus 10 includes a first control unit 21, a transmission / reception I / F unit 22, a patch holding unit 23, a correction data holding unit 24, an operation display unit 25, a printing unit 26, and the like.

  The first control unit 21 includes a CPU, a ROM, a RAM, a hard disk device, and the like, and controls the entire operation of the printing apparatus 10 by executing a program stored in the ROM or the hard disk device.

  Regarding gradation correction, the first control unit 21 executes low resolution calibration using the gradation correction unit 30, the first calibration execution unit 31 that executes high resolution calibration using the printing unit 26, and the printing unit 26. The second calibration execution unit 32 and the estimated value deriving unit 33 that performs the estimation calibration are performed. The tone correction unit 30 refers to the tone correction data held in the correction data holding unit 24 and corrects the tone value of the print data (image data after rasterization) with the tone correction data.

  The transmission / reception I / F unit 22 transmits / receives print data and other information to / from an external device such as the client PC 5. The patch holding unit 23 holds image data of various patches. The correction data holding unit 24 executes high-resolution gradation correction data, low-resolution gradation correction data, measurement data obtained by optically reading a patch when high-resolution calibration is executed, and low-resolution calibration. Measurement data obtained by optically reading the patch is stored.

  The operation display unit 25 includes a liquid crystal display, an operation switch, and the like, and displays a setting screen and a screen showing the state of the apparatus and receives various settings from the user.

  The printing unit 26 has a function of forming an image on a sheet. The printing unit 26 includes a mechanism shown in FIG. 1 and a second control unit 27 that controls the mechanism and takes in an output signal from the density sensor 18. The second control unit 27 includes a CPU, a ROM, a RAM, and the like. The second control unit 27 outputs a request for performing low resolution calibration or a request for performing high resolution calibration to the first control unit 21 according to the state of the printing unit 26 or the like.

  When the printing apparatus 10 receives print data from the client PC 5, the first control unit 21 rasterizes the print data to generate image data, and the gradation correction unit 30 performs gradation correction on the image data. After image processing, the image data is sent to the printing unit 26. The printing unit 26 forms an image corresponding to the received image data on a sheet and prints it out.

  In the printing, when printing at high resolution, the tone correction unit 30 performs tone correction on the image data to be printed using the high-resolution tone correction data held in the correction data holding unit 24. Further, when printing at a low resolution, the gradation correction unit 30 performs gradation correction on the image data to be printed using the low-resolution gradation correction data held in the correction data holding unit 24.

  When a request for performing low resolution calibration is generated, such as when starting up or printing a certain number of sheets, the first control unit 21 executes low resolution calibration in the second calibration execution unit 32 and stores the correction data in the correction data holding unit 24. The stored low resolution gradation correction data is updated with the low resolution gradation correction data obtained as a result of the low resolution calibration.

  More specifically, the second calibration execution unit 32 outputs the image data of the low resolution patches (CMYK color screen patches corresponding to the low resolution) held in the patch holding unit 23 to the second control unit of the printing unit 26. 27, these patches are image-formed on the intermediate transfer belt 11. The second control unit 27 of the printing unit 26 reads the density of each patch on the intermediate transfer belt 11 using the density sensor 18 and transmits the measurement data obtained by the reading to the first control unit 21. The second calibration execution unit 32 of the first control unit 21 generates low-resolution gradation correction data from the measurement data received from the second control unit 27, and stores this in the correction data holding unit 24 to hold it.

  When the update timing of the high-resolution gradation correction data arrives, the first control unit 21 selects and determines whether to perform high-resolution calibration or estimation calibration. The update factors of the high-resolution gradation correction data include (1) those caused by a high-resolution print request and (2) those caused by a low-resolution calibration situation. Details will be described later.

  When the first control unit 21 selects the high resolution calibration, the first calibration execution unit 31 executes the high resolution calibration, and the high resolution gradation obtained as the execution result of the high resolution calibration. The high-resolution gradation correction data held in the correction data holding unit 24 is updated with the correction data.

  More specifically, the first calibration execution unit 31 uses the image data of the high resolution patches (CMYK color screen patches corresponding to the high resolution) held in the patch holding unit 23 as the second control unit of the printing unit 26. 27, these patches are image-formed on the intermediate transfer belt 11. The second control unit 27 of the printing unit 26 reads the density of each patch on the intermediate transfer belt 11 using the density sensor 18 and transmits the measurement data obtained by the reading to the first control unit 21. The first calibration execution unit 31 of the first control unit 21 generates high-resolution gradation correction data from the measurement data received from the second control unit 27, and stores this in the correction data holding unit 24 to hold it.

  When the first calibration unit 21 selects the estimated calibration, the estimated value deriving unit 33 executes the estimated calibration, and the estimated value obtained as a result of the execution is held in the correction data holding unit 24. Update high-resolution gradation correction data. The estimated value deriving unit 33 obtains an estimated value of the high-resolution gradation correction data by applying a predetermined estimation algorithm to the latest low-resolution gradation correction data stored in the correction data holding unit 24.

  The estimation calibration is performed in parallel with the process in which the first control unit 21 rasterizes the print data.

  FIG. 3 shows processing when the high-resolution correction data is updated due to a high-resolution print request. This process is performed when printing at a high resolution is instructed from the client PC 5 or the like and printing at a high resolution is started.

  The first control unit 21 checks whether or not a request for performing high resolution calibration is generated as a predetermined weighting condition based on a printing history at high resolution (step S101). Since the execution request for the high resolution calibration is generated based on the number of printed sheets at the high resolution, the predetermined weighting condition is set based on the history of printing at the high resolution. The first control unit 21 does not update the high-resolution gradation correction data held in the correction data holding unit 24 when the high-resolution calibration execution request is not generated (step S101; No). The process proceeds to step S106.

  When the execution request for the high resolution calibration is generated (step S101; Yes), the first control unit 21 checks whether the print mode of the current printing is speed priority or image quality priority (step S102).

  In the case of speed priority (step S102; Yes), the first control unit 21 causes the estimated value deriving unit 33 to perform estimation calibration to obtain an estimated value of high-resolution gradation correction data (step S103). Then, the high-resolution gradation correction data held in the correction data holding unit 24 is updated with the estimated value obtained in step S103 (step S105), and the process proceeds to step S106.

  When priority is given to image quality (step S102; No), the first control unit 21 causes the first calibration execution unit 31 to perform high resolution calibration to newly obtain high resolution gradation correction data (step S104). Then, the high-resolution gradation correction data held in the correction data holding unit 24 is updated with the high-resolution gradation correction data obtained in step S104 (step S105), and the process proceeds to step S106.

  In step S106, the gradation correction unit 30 performs gradation correction of the print data (image data after rasterization) with reference to the high-resolution gradation correction data held in the correction data holding unit 24. Then, the first control unit 21 transmits the print data after the gradation correction to the printing unit 26, causes the printing unit 26 to perform printing based on the printing data (step S107), and ends this processing.

  In the above processing, when the print mode is image quality priority, high-resolution calibration is performed and the high-resolution gradation correction data is updated, so gradation correction is performed with high accuracy and high-quality printing is performed. Can do. On the other hand, when the print mode is speed priority, the estimated calibration is performed, so that the time until the start of printing (first print time) can be shortened compared to the case where the high resolution calibration is performed. In addition, toner consumption can be reduced by performing estimation calibration that does not form an image of a patch, instead of high-resolution calibration that actually forms an image of a patch.

  Next, a case where the high-resolution gradation correction data is updated based on the state of low-resolution calibration will be described. There are multiple types of this process. Hereinafter, each process will be described.

  FIG. 4 shows the high-resolution gradation correction data according to the difference between the low-resolution gradation correction data obtained by the current low-resolution calibration and the low-resolution gradation correction data obtained by the previous low-resolution calibration. Shows the processing for updating.

  This process is executed when the first control unit 21 or the second control unit 27 issues a low resolution calibration execution request. First, the first control unit 21 causes the second calibration execution unit 32 to execute low resolution calibration in response to an execution request for low resolution calibration (step S201).

  Next, the previous low resolution calibration execution result (low resolution gradation correction data or measurement data obtained by reading a patch when low resolution calibration is performed) is read from the correction data holding unit 24 ( In step S202), the previous low resolution calibration execution result and the current low resolution calibration execution result are compared, and the difference is calculated (step S203). The difference is a gradation difference, a color difference, a gradation difference average, or the like.

  If the calculated difference is equal to or less than the first threshold value determined in advance (step S204; No), the process proceeds to step S209. If the difference between the previous low-resolution calibration execution result and the current low-resolution calibration execution result is less than or equal to the first threshold value, the change in the gradation characteristic is small. It can be estimated that there are few. Therefore, it is determined that there is no need to update the high-resolution gradation correction data.

  If the calculated difference is larger than the first threshold (step S204; Yes), it can be estimated that a certain degree of change has occurred in the gradation characteristics when printing at high resolution. It is determined that the high-resolution gradation correction data needs to be updated. Then, it is determined whether the update is performed by high resolution calibration or estimation calibration.

  Specifically, it is determined whether or not the difference exceeds a second threshold value that is greater than the first threshold value (step S205). If the difference exceeds the second threshold value (step S205; Yes), high resolution calibration is performed. If the difference exceeds the first threshold but is less than or equal to the second threshold (step S205; No), the estimated calibration is performed (step S206).

  If the difference between the previous and current low-resolution calibration results is so large that it exceeds the second threshold, it can be estimated that the tone characteristics have changed significantly even in high-resolution printing, so the patch is actually formed. Perform high resolution calibration. On the other hand, if the difference between the previous and current low-resolution calibration results is less than or equal to the second threshold value, it can be estimated that the gradation characteristics in high-resolution printing have not changed significantly. Update high-resolution gradation correction data.

  When the high resolution calibration is performed in step S207, the high resolution gradation correction data held in the correction data holding unit 24 is updated with the gradation correction data obtained by the high resolution calibration (step S207). S208), the process proceeds to step S209. When the estimation calibration is performed in step S206, the high-resolution gradation correction data held in the correction data holding unit 24 is updated with the estimated value of the gradation correction data obtained by the estimation calibration ( Step S208) and the process proceeds to Step S209.

  In step S209, the current low-resolution calibration execution result is stored in the correction data holding unit 24. Then, this process ends.

  As described above, based on the difference between the previous and current low resolution calibration results, it is necessary to update the high resolution tone correction data, and if the update is necessary, estimate whether to update by performing the high resolution calibration. Since it is determined whether or not to update by performing calibration, the high-resolution floor is more accurate than when determining whether or not to update the high-resolution tone correction data based on the number of printed sheets and the elapsed time. The update of the tone correction data can be determined, and unnecessary update can be prevented.

  In normal use, since the frequency of printing at high resolution is low, the necessity of high-resolution gradation correction data is determined from the result of low-resolution calibration.

  FIG. 5 shows processing when the high-resolution gradation correction data is updated in accordance with the number of times the low-resolution calibration is performed. This process is executed when the first control unit 21 or the second control unit 27 issues a low resolution calibration execution request.

  First. In response to the execution request for the low resolution calibration, the first control unit 21 causes the second calibration execution unit 32 to execute the low resolution calibration (step S301).

  Next, the count value N of the execution number counter for counting the number of executions of the low resolution calibration is incremented by 1 (step S302). The execution number counter counts the number of executions of the low resolution calibration performed after the high resolution calibration. If the count value N of the execution number counter is equal to or smaller than the third threshold value (step S303; No), the process proceeds to step S309.

  When the count value N of the execution number counter is larger than the third threshold (step S303; Yes), it is estimated that a certain change has occurred in the gradation characteristics when printing at high resolution, and gradation correction for high resolution is performed. Judge that the data needs to be updated. Then, it is determined whether the update is performed by high resolution calibration or estimation calibration.

  Specifically, it is determined whether or not the count value N of the execution number counter exceeds a fourth threshold value that is greater than the third threshold value (step S304). If the count value N exceeds the fourth threshold value (step S304) (S304; Yes), high resolution calibration is performed (step S306), and if the count value N exceeds the third threshold value but is equal to or less than the fourth threshold value (step S304; No), estimated calibration is performed (step S304; No). Step S305).

  When the count value N of the execution counter exceeds the fourth threshold value, it is highly likely that the gradation characteristics have changed greatly in high-resolution printing, so high-resolution calibration that actually forms the patch is performed. To do. On the other hand, if the count value N of the execution counter is equal to or smaller than the fourth threshold value, it can be estimated that the gradation characteristics in high-resolution printing have not changed so much, so that estimation calibration is performed to perform gradation correction for high resolution. Update the data.

  When the high resolution calibration is performed in step S306, the execution number counter is reset to 0 (step S307), and the high level held in the correction data holding unit 24 by the gradation correction data obtained by the high resolution calibration. The resolution gradation correction data is updated (step S308), and the process proceeds to step S309. When the estimation calibration is performed in step S305, the high-resolution gradation correction data held in the correction data holding unit 24 is updated with the estimated value of the gradation correction data obtained by the estimation calibration ( Step S308) and the process proceeds to Step S309.

  In step S309, the current low resolution calibration execution result is stored in the correction data holding unit 24. Then, this process ends.

  Based on the number of times low resolution calibration has been performed since high resolution calibration is performed in this way, it is necessary to update high resolution gradation correction data, and if high resolution calibration is required, perform high resolution calibration. Since it is determined whether to update or perform estimation calibration, it is more accurate than when judging whether to update the high-resolution gradation correction data based on the number of printed sheets and the elapsed time, The update of the high-resolution gradation correction data can be determined, and unnecessary updates can be prevented.

  In normal use, since the frequency of printing at high resolution is low, the necessity of high-resolution gradation correction data is determined from the result of low-resolution calibration.

  FIG. 6 shows processing when the high-resolution gradation correction data is updated according to the elapsed time from the previous low-resolution calibration. This process is executed when the first control unit 21 or the second control unit 27 issues a low resolution calibration execution request.

  First. In response to the execution request for the low resolution calibration, the first control unit 21 causes the second calibration execution unit 32 to execute the low resolution calibration (step S401).

  Next, an elapsed time T since the previous low-resolution calibration was performed is calculated (step S402). If the elapsed time T is less than or equal to the fifth threshold (step S403; No), the process proceeds to step S408.

  When the printing frequency and the number of prints are small, the elapsed time (execution interval) from the execution of the previous low resolution calibration to the execution of the next low resolution calibration becomes longer. Therefore, in such a case, whether or not it is necessary to update the high-resolution gradation correction data based on the elapsed time since the previous low-resolution calibration was performed, that is, the execution interval of the low-resolution calibration. to decide.

  If the elapsed time T is less than or equal to the fifth threshold value, it can be estimated that the change in gradation characteristics in high-resolution printing is still small, so it is determined that there is no need to update the high-resolution gradation correction data.

  If the elapsed time T is greater than the fifth threshold (step S403; Yes), there is a possibility that some change has occurred in the gradation characteristics when printing at high resolution. Judge that update is necessary. Then, it is determined whether the update is performed by high resolution calibration or estimation calibration.

  Specifically, it is determined whether or not the elapsed time T exceeds a sixth threshold value that is greater than the fifth threshold value (step S404). When the elapsed time T exceeds the sixth threshold value (step S404; Yes) Then, high-resolution calibration is performed (step S406), and if the elapsed time T exceeds the fifth threshold but is less than or equal to the sixth threshold (step S404; No), estimation calibration is performed (step S405).

  When the high resolution calibration is performed in step S406, the high resolution gradation correction data held in the correction data holding unit 24 is updated with the gradation correction data obtained by the high resolution calibration (step S406). S407), the process proceeds to step S408. When the estimation calibration is performed in step S405, the high-resolution gradation correction data held in the correction data holding unit 24 is updated with the estimated value of the gradation correction data obtained by the estimation calibration ( Step S407) and the process proceeds to Step S408.

  In step S408, the current execution time of the low resolution calibration is stored. Thereafter, the execution result of the current low resolution calibration is stored in the correction data holding unit 24 (step S409), and this process ends.

  Thus, based on the elapsed time since the previous low-resolution calibration, whether or not to update the high-resolution gradation correction data is necessary, and if necessary, the high-resolution calibration is performed and updated. Therefore, even if the number of prints is small and the interval between low-resolution calibrations is long, the high-resolution level is determined from the low-resolution calibration. It is possible to appropriately determine whether or not the key correction data needs to be updated and the updating method, and it is possible to prevent unnecessary updating.

  The embodiment of the present invention has been described with reference to the drawings. However, the specific configuration is not limited to that shown in the embodiment, and there are changes and additions within the scope of the present invention. Are also included in the present invention.

  In the printing apparatus 10, the processes in FIGS. 4 to 6 may be applied in duplicate.

  In the embodiment, a high-resolution calibration and a low-resolution calibration are provided as calibration for generating gradation correction data by forming an image of a patch and reading the patch. Although an example has been shown in which an estimated value of the implementation result is obtained, the calibration for forming an image of the patch is not limited to high resolution and low resolution. For example, the first calibration function that generates strict gradation correction data using a large number of patches and the second calibration function that generates gradation correction data using a small number of patches even at the same resolution. The present invention also includes a case where the estimated value of the execution result of the first calibration is obtained from the execution result of the second calibration in the estimation calibration.

  In the processing of FIGS. 4 to 6 of the embodiment, it is determined whether the high-resolution gradation correction data needs to be updated based on the first threshold value, the third threshold value, and the fifth threshold value, and the second threshold value, the fourth threshold value, and the fourth threshold value. Whether to use the high resolution calibration or the estimation calibration is selected based on the threshold and the sixth threshold. For example, the determination based on the first threshold, the third threshold, and the fifth threshold is omitted, and the second threshold is used. If the fourth threshold value and the sixth threshold value are exceeded, high resolution calibration is performed. If not, nothing is done (high resolution gradation correction data is not updated).

5 ... Client PC
6 ... Transmission / reception I / F unit 7 ... Print data generation processing unit 10 ... Printing device 11 ... Intermediate transfer belt 12 ... Post-processing device 12Y, 12M, 12C, 12K ... Image forming unit 13 ... Paper feed unit 13a ... Paper feed tray 14 ... Conveying unit 15 ... Fixing device 16 ... Photosensitive drum 17 ... Laser unit 18 ... Density sensor 21 ... First control unit 22 ... Transmission / reception I / F unit 23 ... Patch holding unit 24 ... Correction data holding unit 25 ... Operation display unit 26 DESCRIPTION OF SYMBOLS ... Printing part 27 ... 2nd control part 30 ... Tone correction part 31 ... 1st calibration execution part 32 ... 2nd calibration execution part 33 ... Estimated value deriving part A ... Arrow which shows rotation direction D ... Secondary transfer position

Claims (8)

A gradation correction unit that performs gradation correction of print data;
A printing unit that prints based on print data that has undergone gradation correction by the gradation correction unit;
A holding unit for holding first-type gradation correction data used by the gradation correction unit for gradation correction;
A reading unit for optically reading an image formed by the printing unit;
A first calibration execution unit that performs a first calibration for generating first-gradation correction data from measurement data obtained by forming an image of a patch on the printing unit and optically reading the patch by the reading unit When,
A second calibration execution unit that performs a second calibration for generating second-type gradation correction data from measurement data obtained by causing the printing unit to form a patch image and optically reading the patch by the reading unit. When,
An estimated value deriving unit for deriving an estimated value of the first type gradation correction data based on the second type gradation correction data;
When updating the first type gradation correction data held in the holding unit, it is determined whether to use the first calibration execution unit or the estimated value derivation unit, and the first calibration execution is performed. The first-type gradation correction data held in the holding unit is updated with the first-type gradation correction data obtained by causing the first calibration execution unit to execute the first calibration. When using the estimated value deriving unit, a control unit that updates the first-type gradation correction data held in the holding unit with the estimated value obtained by deriving the estimated value deriving unit;
I have a,
The first type gradation correction data is gradation correction data used when printing at the first resolution,
The second type gradation correction data is gradation correction data used when printing at a second resolution lower than the first resolution,
In the determination, the control unit selects use of the first calibration execution unit when the print mode is set to image quality priority, and the estimated value when the print mode is set to speed priority. A printing apparatus characterized by selecting use of a deriving unit . The control unit performs the update when receiving an instruction to print at the first resolution and when a predetermined weighting condition based on a printing history at the first resolution is satisfied. The printing apparatus according to claim 1 . A gradation correction unit that performs gradation correction of print data;
A printing unit that prints based on print data that has undergone gradation correction by the gradation correction unit;
A holding unit for holding first-type gradation correction data used by the gradation correction unit for gradation correction;
A reading unit for optically reading an image formed by the printing unit;
A first calibration execution unit that performs a first calibration for generating first-gradation correction data from measurement data obtained by forming an image of a patch on the printing unit and optically reading the patch by the reading unit When,
A second calibration execution unit that performs a second calibration for generating second-type gradation correction data from measurement data obtained by causing the printing unit to form a patch image and optically reading the patch by the reading unit. When,
An estimated value deriving unit for deriving an estimated value of the first type gradation correction data based on the second type gradation correction data;
When updating the first type gradation correction data held in the holding unit, it is determined whether to use the first calibration execution unit or the estimated value derivation unit, and the first calibration execution is performed. The first-type gradation correction data held in the holding unit is updated with the first-type gradation correction data obtained by causing the first calibration execution unit to execute the first calibration. When using the estimated value deriving unit, a control unit that updates the first-type gradation correction data held in the holding unit with the estimated value obtained by deriving the estimated value deriving unit;
Have
The control unit is configured to obtain a difference between the second type gradation correction data obtained in the second calibration of the current time and the second type gradation correction data obtained in the previous second calibration, or the current second type of gradation correction data. If the difference between the measurement data obtained by optically reading the patch in two calibrations and the measurement data obtained by optically reading the patch in the previous second calibration is greater than or equal to the first threshold value, the holding is performed. The determination is made by determining that the first-type gradation correction data held in the unit needs to be updated. In the determination, if the difference is greater than the first threshold and less than the second threshold, the estimation is performed. select use value deriving unit, if the difference is greater than the second threshold value printing device you and selects the use of the first calibration execution unit. A gradation correction unit that performs gradation correction of print data;
A printing unit that prints based on print data that has undergone gradation correction by the gradation correction unit;
A holding unit for holding first-type gradation correction data used by the gradation correction unit for gradation correction;
A reading unit for optically reading an image formed by the printing unit;
A first calibration execution unit that performs a first calibration for generating first-gradation correction data from measurement data obtained by forming an image of a patch on the printing unit and optically reading the patch by the reading unit When,
A second calibration execution unit that performs a second calibration for generating second-type gradation correction data from measurement data obtained by causing the printing unit to form a patch image and optically reading the patch by the reading unit. When,
An estimated value deriving unit for deriving an estimated value of the first type gradation correction data based on the second type gradation correction data;
When updating the first type gradation correction data held in the holding unit, it is determined whether to use the first calibration execution unit or the estimated value derivation unit, and the first calibration execution is performed. The first-type gradation correction data held in the holding unit is updated with the first-type gradation correction data obtained by causing the first calibration execution unit to execute the first calibration. When using the estimated value deriving unit, a control unit that updates the first-type gradation correction data held in the holding unit with the estimated value obtained by deriving the estimated value deriving unit;
Have
Wherein, based on the execution count of the second calibration is performed after the last execution of the first calibration, printing device you and performing the determination. When the number of executions is equal to or greater than a third threshold, the control unit determines that the first-type gradation correction data held in the holding unit needs to be updated and performs the determination. When the number of executions is greater than the third threshold and less than the fourth threshold, use of the estimated value deriving unit is selected, and when the number of executions is greater than or equal to the fourth threshold, use of the first calibration execution unit is selected. The printing apparatus according to claim 4 , wherein the printing apparatus is selected. A gradation correction unit that performs gradation correction of print data;
A printing unit that prints based on print data that has undergone gradation correction by the gradation correction unit;
A holding unit for holding first-type gradation correction data used by the gradation correction unit for gradation correction;
A reading unit for optically reading an image formed by the printing unit;
A first calibration execution unit that performs a first calibration for generating first-gradation correction data from measurement data obtained by forming an image of a patch on the printing unit and optically reading the patch by the reading unit When,
A second calibration execution unit that performs a second calibration for generating second-type gradation correction data from measurement data obtained by causing the printing unit to form a patch image and optically reading the patch by the reading unit. When,
An estimated value deriving unit for deriving an estimated value of the first type gradation correction data based on the second type gradation correction data;
When updating the first type gradation correction data held in the holding unit, it is determined whether to use the first calibration execution unit or the estimated value derivation unit, and the first calibration execution is performed. The first-type gradation correction data held in the holding unit is updated with the first-type gradation correction data obtained by causing the first calibration execution unit to execute the first calibration. When using the estimated value deriving unit, a control unit that updates the first-type gradation correction data held in the holding unit with the estimated value obtained by deriving the estimated value deriving unit;
Have
Wherein, when the number of executions of the second calibration is performed after the last execution of the first calibration is larger than a predetermined number of times, to execute the first calibration in the first calibration execution unit obtained was first Tanekaicho correction data in printing apparatus you and updates the first Tanekaicho correction data held in the holding unit. A gradation correction unit that performs gradation correction of print data;
A printing unit that prints based on print data that has undergone gradation correction by the gradation correction unit;
A holding unit for holding first-type gradation correction data used by the gradation correction unit for gradation correction;
A reading unit for optically reading an image formed by the printing unit;
A first calibration execution unit that performs a first calibration for generating first-gradation correction data from measurement data obtained by forming an image of a patch on the printing unit and optically reading the patch by the reading unit When,
A second calibration execution unit that performs a second calibration for generating second-type gradation correction data from measurement data obtained by causing the printing unit to form a patch image and optically reading the patch by the reading unit. When,
An estimated value deriving unit for deriving an estimated value of the first type gradation correction data based on the second type gradation correction data;
When updating the first type gradation correction data held in the holding unit, it is determined whether to use the first calibration execution unit or the estimated value derivation unit, and the first calibration execution is performed. The first-type gradation correction data held in the holding unit is updated with the first-type gradation correction data obtained by causing the first calibration execution unit to execute the first calibration. When using the estimated value deriving unit, a control unit that updates the first-type gradation correction data held in the holding unit with the estimated value obtained by deriving the estimated value deriving unit;
Have
When the second calibration execution interval is equal to or greater than the fifth threshold, the control unit determines that the first-type gradation correction data held in the holding unit needs to be updated and performs the determination. In the determination, if the execution interval is greater than the fifth threshold and less than the sixth threshold, the use of the estimated value deriving unit is selected, and if the execution interval is greater than or equal to the sixth threshold, the first calibration is performed. printing apparatus you and selects the use of Deployment execution unit. The first type gradation correction data is gradation correction data used when printing at the first resolution,
  The second type gradation correction data is gradation correction data used when printing at a second resolution lower than the first resolution.
  The printing apparatus according to claim 3, wherein the printing apparatus is a printer.

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