JP2011027720A - Printer and method of controlling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for performing correction of a colorimetry value by temperature with an easy method and constitution. <P>SOLUTION: A patch to be printed is fixed to a printing position on a recording medium, the color of the patch to be printed is measured after the fixing, and the white paper temperature of the recording medium is measured. Using a previously determined relative temperature value and the measured white paper temperature for the patch to be printed that is printed at a printing position on the recording medium, a temperature on the basis of the measured white paper temperature of the patch fixed to the printing position is determined as a temperature used for correcting the colorimetry value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a printing technique.

  The phenomenon in which the colorimetric value of a colored object changes with temperature is called thermochromism. This phenomenon gives an error to the colorimetric value according to the temperature of the object to be measured, which is an obstacle in a scene where high-precision colorimetry is required. The color variation that causes the error varies substantially linearly with temperature and is reversible.

  This color variation is classified into a variation due to the influence of a fluorescent material such as a fluorescent brightening agent contained in the medium and a variation due to the influence of a non-fluorescent material such as a toner component. Further, the spectral reflectance of the fluorescent material changes in the vertical direction depending on the temperature as shown in FIG. 4A, and the spectral reflectance of the non-fluorescent material depends on the temperature as shown in FIG. 4B. I found out that it changed in the horizontal direction.

  Here, the fluorescent whitening material contained in the medium which is a fluorescent material will be described. In general, some media used for printing include a fluorescent whitening agent that absorbs ultraviolet light and emits fluorescence in the visible range in order to increase whiteness. The fluorescent whitening effect by the fluorescent whitening agent increases or decreases depending on the temperature. For this reason, the colorimetric value of the printed matter output to the medium containing the fluorescent brightening agent varies depending on the temperature.

  Here, color stabilization and color matching processing in the printing apparatus will be described. Conventionally, a color conversion look-up table (LUT) has been used to output a desired color in a printing apparatus typified by an electrophotographic printer apparatus. The color conversion LUT includes an LUT for use in calibration for keeping the printing apparatus in a certain state, an LUT for use in color matching represented by an ICC profile, and the like. In order to create these color conversion LUTs, for example, a plurality of color charts such as IT87 7/3 patches are output from the printing apparatus. Then, by measuring these multiple color charts using a colorimeter such as a spectrophotometer, colorimetric values are obtained, device values are associated with non-device-dependent values, and a color conversion LUT is created. To do. This created LUT absorbs color differences between devices and color differences due to printer engine fluctuations to achieve color matching and color stabilization. Recently, this LUT is generated in real time using a color sensor mounted inside the electrophotographic printer.

  Conventionally, the following method has been proposed as a method of correcting a colorimetric value change depending on temperature. For example, a technique is disclosed in which a spectral reflectance change amount for each wavelength per unit temperature is obtained in advance for each colored sample, and a spectral reflectance at a target temperature is predicted (see Patent Document 1). In addition, a technique is disclosed in which the amount of change in the absorption coefficient and the scattering coefficient in the Kubelka-Munk equation for each wavelength per unit temperature is obtained for each colored sample, and the spectral reflectance at the target temperature is predicted (see Patent Document 2). .

Japanese Patent No. 03776492 Japanese Patent No. 03555706

  Even for an output product having a constant temperature immediately after fixing, the temperature of the patch on the discharged paper transported by a fixed distance from the fixing differs for each colorimetric position. This is because temperature irregularities occur for each patch due to characteristics of the fixing roller, air cooling during conveyance, and the like. For this reason, in order to accurately correct the colorimetric value by temperature, the target patch temperature must be measured one by one for each colorimetry using a radiation thermometer or the like. The system becomes expensive or complicated. The prior art has the above-described problems. The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique for correcting a colorimetric value by temperature with a simpler method and configuration.

  In order to achieve the object of the present invention, for example, a printing apparatus of the present invention has the following configuration. That is, a printing apparatus that corrects a colorimetric result of a patch printed on a recording medium by using the temperature of the patch, the recording target obtained in advance for a printing target patch to be printed at a printing position on the recording medium. Means for storing a relative temperature value of the print target patch with respect to the paper white temperature of the medium; fixing means for fixing the print target patch to the print position; and printing fixed at the print position after the fixing Using the color measuring means for measuring the target patch, the measuring means for measuring the paper white temperature of the recording medium, the relative temperature value, and the paper white temperature measured by the measuring means, And calculating means for obtaining a temperature based on the measured paper white temperature of the fixed patch as a temperature used for correcting a colorimetric value by the colorimetric means.

  According to the configuration of the present invention, it is possible to correct the colorimetric value based on the temperature with a simpler method and configuration.

FIG. 3 is a block diagram illustrating a functional configuration example of a printer apparatus. The figure which shows the function structural example of the colorimetric value temperature correction | amendment part 114. FIG. Block diagram showing a functional configuration example of the printer device 41 (A) is a figure which shows the spectral reflectance of a fluorescent substance, (b) is a figure which shows the spectral reflectance of a non-fluorescent substance, (c) is a figure which shows the structural example of patch temperature nonuniformity characteristic LUT11511. 10 is a flowchart of a method for creating a patch temperature unevenness characteristic LUT11511. The block diagram which shows the structural example of the patch temperature correction | amendment part 115. FIG. 9 is a flowchart of processing for correcting a calibration LUT 1121. The block diagram which shows the function structural example of the colorimetric value temperature correction | amendment part 14114. FIG. FIG. 3 is a block diagram illustrating a functional configuration example of a printer apparatus 1401. The block diagram which shows the function structural example of the patch temperature correction | amendment part 15115. FIG. The flowchart of the process for obtaining a colorimetric value. The flowchart of the production | generation process of the patch temperature fall amount correction characteristic table 11513. FIG. The figure which shows the relationship between a toner applied amount and the temperature of a patch. The figure which shows the temperature nonuniformity measurement system for obtaining the patch temperature nonuniformity characteristic LUT.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. The embodiment described below shows an example when the present invention is specifically implemented, and is one of the specific examples of the configurations described in the claims.

[First Embodiment]
In the present embodiment, colorimetric value temperature correction in an electrophotographic printer device (printing device) equipped with a color sensor will be described. FIG. 1 is a block diagram illustrating a functional configuration example of the printer apparatus according to the present embodiment. The printer device according to the present embodiment prints out a color chart (a patch group) for calibration immediately before or during normal printing, and prints each patch on the recording medium in the printer device. The colorimetric sensor measures colors. As a result, the calibration LUT 1121 is generated and updated, and the print output state is kept constant. The printer device 1 is roughly divided into a controller unit 11 and an engine unit 12.

  The controller unit 11 includes a color matching unit 111, a calibration unit 112, a calibration LUT generation unit 113, a colorimetric value temperature correction unit 114, and a patch temperature correction unit 115. The engine unit 12 includes a fixing unit 121, a temperature sensor unit 122, a color sensor unit 123, a transfer belt (not shown), a laser unit 129, and the like. In FIG. 1, only the components that appear in the following description in the controller unit 11 and the engine unit 12 are shown, and the other components are omitted.

  First, the controller unit 11 will be described. The color matching unit 111 holds a color matching LUT 1111 typified by an ICC profile. The color matching unit 111 performs processing for adjusting a color (CMYK value in this case) input from the external apparatus (host PC) using the color matching LUT 1111. When the color matching unit 111 receives a patch print instruction from the host PC, the color matching unit 111 sends print position information 1113 indicating the print position of each patch included in the print instruction to the patch temperature correction unit 115. To do. Note that the patch printing position information 1113 and the CMYK value 1112 are stored in advance in a memory (not shown) in the printer apparatus 1, and can be read by the calibration LUT generation unit 113 and the colorimetric value temperature correction unit 114 as appropriate. good. The calibration process is not limited to starting in response to an instruction from an external device. For example, the calibration process may be executed automatically (periodically), or the calibration process may be started in response to an instruction (input) for the user to perform a calibration process on the printer apparatus.

  The calibration unit 112 holds, for example, a calibration LUT 1121 for converting the color adjusted by the color matching unit 111 (here, the device value CMYK) into CMYK-CMYK in a multidimensional manner. Therefore, the calibration unit 112 uses the calibration LUT 1121 to perform color correction processing for keeping the printing state constant. The patch temperature correction unit 115 calculates patch temperature information corresponding to the printing position information 1113 using the following information when printing a patch. That is, the temperature information 1221 indicating the temperature measured by the temperature sensor unit 122, the print position information 1113 from the color matching unit 111, and the patch temperature unevenness characteristic LUT 11511 held in advance by the patch temperature correction unit 115.

  Then, the patch temperature correction unit 115 sends the patch temperature information corresponding to the print position information 1113 to the colorimetric value temperature correction unit 114 as the correction temperature 1152. The colorimetric value temperature correction unit 114 receives the colorimetric value 1231 from the color sensor unit 123, the correction temperature 1152 received from the patch temperature correction unit 115, the color processed by the color matching unit 111 (CMYK value 1112), Correct based on The colorimetric value 1231 is expressed by a Lab value, for example. Then, the corrected colorimetric value 1231 is sent to the calibration LUT generation unit 113 as a corrected colorimetric value 1142. As shown in FIG. 2, the colorimetric value temperature correction unit 114 uses, as inputs, the device value (CMYK) 21112 of the patch, the temperature characteristic LUT 21141, the temperature 21221 of the input patch, and the colorimetric value 21231 obtained from the color sensor unit 123. A corrected colorimetric value 21142 is obtained. The device value 21112 of the patch is assumed to be a color measurement target. In addition, the temperature characteristic LUT 21141 measures a colorimetric value variation amount corresponding to a temperature change for each of a plurality of patches (reference patches) having some typical device values from all combinations of patches in advance and forms a table. It is a thing.

  The calibration LUT generation unit 113 uses the color after processing by the color matching unit 111 and the corrected colorimetric value 1142 by the colorimetric value temperature correction unit 114 to hold a calibration LUT 1121 held by the calibration unit 112. Update.

  Then, based on the calibration data sent from the calibration unit 112, an image is formed on the photosensitive drum (not shown) by the laser unit 129. First, a photosensitive drum is charged by a charging roller (not shown), and a laser is irradiated on the charged photosensitive drum to form an electrostatic latent image (exposure). Next, the electrostatic latent image on the photosensitive drum is developed by a developing device (not shown) to form a toner image. Next, the toner image on the photosensitive drum is copied onto a transfer belt (not shown), and the toner image is transferred to a sheet by the transfer belt (transfer). Next, the toner image on the paper is melted and fixed by a fixing device by heat and pressure (fixing). Thereby, images such as characters and patches can be printed on a recording medium such as paper.

  The temperature sensor unit 122 is for measuring the temperature at a predetermined position on the recording medium or the ambient temperature of the recording medium. The color sensor unit 123 is for measuring the color at a predetermined position on the recording medium. The color sensor unit 123 sends the measured colorimetric value 1231 to the colorimetric value temperature correction unit 114 in the form of Lab value, XYZ value, or spectral data. The temperature sensor unit 122 and the color sensor unit 123 are installed in the conveyance path from the fixing unit 121 to the paper discharge port. In the case of a copying machine in which a document reading unit (not shown) is mounted on the printer device, the recording medium discharged from the fixing unit 121 is automatically conveyed to the document reading unit, and the document reading unit is used as the color sensor unit 123. It is also possible to function. In this case, although a mechanism for conveying to the document reading unit is required, the color sensor unit 123 can be substituted by the document reading unit.

  Next, a method for creating the patch temperature unevenness characteristic LUT11511 will be described with reference to FIG. 5 showing a flowchart of the method. Note that this processing is performed before product shipment, and is performed using the temperature unevenness measuring system 2 outside the printer and the printer device 1 (fixing unit 121) as shown in FIG.

  In step S <b> 1001, the controller unit 11 uses the data of a plurality of patches recorded in a memory (not illustrated) in the printer device 1 to cause the fixing unit 121 in the engine unit 12 to transfer the plurality of patches 192 to the recording medium 191. Fix on top. Note that the fixing position (printing position) of each patch 192 on the recording medium 191 is determined in advance.

  Next, the recording medium 191 on which the plurality of patches 192 are fixed by the fixing unit 121 is transported onto the transport path. A plurality of temperature sensor units 124 connected to the temperature unevenness measurement system 2 shown in FIG. 14 measure the temperature at each printing position of the patch 192 within the sensor measurement range. The temperature sensor unit 124 is installed at a position in the engine unit 12 where the color sensor unit 123 is installed after product shipment, and measures the temperature on the recording medium 191 at the point where the color sensor measures color. That is, the distance from the temperature sensor unit 124 to the fixing unit 121 is equal to the distance from the color sensor unit 123 to the fixing unit 121 after product shipment. Here, the temperatures at the printing positions of all patches to be printed are recorded.

  Further, the temperature sensor unit 122 built in the printer measures the paper white temperature (or the ambient temperature of the medium, the specific patch temperature) at the position where the patch is not placed on the recording medium 191 simultaneously with the above measurement. As described above, the temperature nonuniformity measurement system 2 uses the relative temperature (relative temperature) between the temperature of all the patches measured by the temperature sensor unit 124 and the paper white temperature (or the media ambient temperature or specific patch temperature) measured by the temperature sensor unit 122. Value). Hereinafter, in this embodiment, the temperature measured by the temperature sensor unit 122 is a paper white temperature. Note that the calibration accuracy may be improved by measuring the paper white temperatures at a plurality of positions on the storage medium 191 using the temperature sensor unit 122.

  Next, in step S1003, the temperature unevenness measurement system 2 uses, for each patch 192, table information registered as a set of positional information on the recording medium 191 and temperature information relative to the paper white temperature as patch temperature unevenness. A characteristic LUT 11511 is created.

  FIG. 4C is a diagram illustrating a configuration example of the patch temperature unevenness characteristic LUT11511. In FIG. 4C, the position on the recording medium (patch position information) and temperature information relative to the paper white temperature (temperature relative value) are registered for each of the 100 patches. The patch position information is indicated by, for example, the distances in the main scanning direction and the sub operation direction from the position of the upper left corner of the recording medium to the position of the patch. The temperature relative value is obtained by the patch temperature correction unit 115 obtaining (patch temperature / paper white temperature) × 100%. The temperature relative value may be a temperature difference between the patch temperature and the paper white temperature.

  By using the patch temperature unevenness characteristic LUT11511, if the paper white temperature T on the recording medium is measured and the position P of an arbitrary patch on the recording medium is designated, the temperature relative value Tm corresponding to the position P × paper By calculating the white temperature T, the temperature of the patch can be obtained. That is, the temperature based on the paper white temperature T of the patch fixed at the printing position P can be obtained. If the paper white temperature T can be regarded as constant, absolute temperature information may be set in the patch temperature unevenness characteristic. As described above, the patch temperature unevenness characteristic LUT 11511 is created from the result of measuring the temperature unevenness on the recording medium in advance, and is registered in the patch temperature correction unit 115 before product shipment.

  Next, a process for correcting the calibration LUT 1121 using the patch temperature unevenness characteristic LUT 11511 created as described above will be described with reference to FIG. 7 showing a flowchart of the process.

  First, in step S1201, the color matching unit 111 receives print data of a patch group having color information expressed in CMYK from the host PC. The color matching unit 111 performs known adjustment processing on the data of each patch (print target patch) included in the print data using the color matching LUT 1111. Then, the color matching unit 111 sends the print position information 1113 of each patch included in the print data to the patch temperature correction unit 115.

  The calibration unit 112 performs a conversion process on each patch adjusted by the color matching unit 111 using the calibration LUT 1121 and fixes each converted patch on the recording medium by the fixing unit 121.

  In step S <b> 1202, the temperature sensor unit 122 measures the paper white temperature T on the recording medium conveyed from the fixing unit 121, and sends the measurement result to the patch temperature correction unit 115.

  In step S <b> 1203, the color sensor unit 123 measures the color of each patch on the recording medium conveyed from the fixing unit 121. Then, the colorimetric value 1231 of each patch is sent to the colorimetric value temperature correction unit 114 as the colorimetric result.

  In step S1204, the patch temperature correction unit 115 first specifies the temperature relative value Tm registered in the patch temperature unevenness characteristic LUT 11511 in combination with the print position information 1113 sent from the color matching unit 111 in step S1201. To do. A result obtained by multiplying the specified temperature relative value Tm by the paper white temperature T sent from the temperature sensor unit 122 in step S1202 is obtained as the correction temperature Tc. Processing for obtaining such a correction temperature Tc is performed for each patch. Then, the patch temperature correction unit 115 sends the correction temperature Tc obtained for each patch to the colorimetric value temperature correction unit 114.

  FIG. 6 is a block diagram illustrating a configuration example of the patch temperature correction unit 115. As described above, since the temperature information 1221 (paper white temperature T) and the printing position information 1113 are input to the patch temperature correction unit 115, the correction amount calculation unit 1151 in the patch temperature correction unit 115 uses these. The correction temperature 1152 (Tc) is obtained by performing the above processing.

  In step S1205, the colorimetric value temperature correction unit 114 calculates the patch colorimetric value acquired from the color sensor unit 123, the correction temperature Tc of the patch, and the CMYK value adjusted by the color matching unit 111 for the patch. And correct using. Such processing is performed for each patch. Thereby, the colorimetric value of each patch can be corrected using the corresponding correction temperature Tc.

  After that, the calibration LUT generation unit 113 uses the colorimetric values corrected by the colorimetric value temperature correction unit 114 for each patch and the adjusted CMYK values of each patch by the color matching unit 111, thereby performing the calibration LUT 1121. Process to update.

  In summary, the printer apparatus according to the present embodiment is for correcting the colorimetric result of the patch printed on the recording medium based on the temperature information of the patch. For that purpose, first, table information is created by registering the print position information of each patch obtained by printing the patch at each position on the recording medium and the temperature relative value with respect to the paper white temperature as a set. Store it. Next, the print target patch that has received the print instruction is printed on a recording medium, and the color measurement value is acquired by measuring the printed print target patch. Next, the print position information of the patch to be printed is acquired, and the temperature relative value registered in the table information as a set with the acquired print position information is acquired from the table information. Finally, the paper white temperature on the recording medium on which the print target patch is printed is acquired, and the acquired colorimetric value is corrected based on the result of multiplying the acquired paper white temperature by the temperature relative value.

[Second Embodiment]
In the first embodiment, every time printing is performed, the paper white temperature T is measured. However, when the paper white temperature T is always constant or when it can be regarded as constant, the patch temperature unevenness characteristic LUT 11511 may be managed as follows.

  FIG. 3 is a block diagram illustrating a functional configuration example of the printer device 41 according to the present embodiment. As shown in FIG. 3, the printer device 41 has a configuration in which the temperature sensor unit 122 is omitted from the printer device 1 according to the first embodiment. Further, the patch temperature unevenness characteristic LUT 11511 is generated by the temperature unevenness measurement system 2 shown in FIG. 14 as in the first embodiment. However, in the second embodiment, the patch temperature unevenness characteristic LUT 11511 does not record the temperature relative value to the paper white temperature, but records the absolute temperature at each printing position. The correction temperature 1152 in the second embodiment is determined only by the print position information 1113 based on the patch temperature unevenness characteristic LUT 11511 and sent to the colorimetric value temperature correction unit 114. The colorimetric value temperature correction unit 114 calculates a corrected colorimetric value 1142 from the CMYK value 1112 sent from the color matching unit 111, the colorimetric value 1231 sent from the color sensor unit 123, and the correction temperature 1152. Send to the calibration LUT 113.

  As described above, the patch temperature unevenness characteristic LUT11511 is configured to have an absolute temperature at each printing position. However, the paper white temperature T may be measured in advance and the patch temperature unevenness characteristic LUT11511 may be configured to have a temperature relative value. Thus, in a situation where the paper white temperature T is always constant or when it can be regarded as constant, a configuration that does not require a mechanism for measuring the paper white temperature is possible.

[Third Embodiment]
FIG. 9 is a block diagram illustrating a functional configuration example of the printer device 1401 according to the present embodiment. In the present embodiment, one LUT (combined LUT) obtained by combining the temperature characteristic LUT 21141 and the patch temperature unevenness characteristic LUT 11511 is stored in the colorimetric value temperature correction unit 14114. Such a combined LUT is a table created by measuring a colorimetric value variation amount corresponding to a temperature change for each of a plurality of patches (reference patches).

  FIG. 8 is a block diagram illustrating a functional configuration example of the colorimetric value temperature correction unit 14114. With such a configuration, it is possible to reduce the calculation cost required for correcting the colorimetric value, and as a result, it is possible to configure a simple system that takes into consideration the amount of temperature change that differs for each patch.

[Fourth Embodiment]
In the first embodiment, temperature in-plane unevenness due to a fixing roller or air cooling is cited as a cause of temperature unevenness on the recording medium, and patch temperature correction is performed using a patch temperature unevenness characteristic LUT11511 that corrects this. However, in the above method, when there is a system corresponding to a plurality of patch patterns, it is necessary to prepare a correction table for each patch pattern. In addition, there is another problem that the applied toner amount cannot correspond to an arbitrary patch pattern.

  Therefore, in the present embodiment, the temperature in-plane unevenness on the recording medium and the temperature drop amount temperature unevenness due to the difference in the applied toner amount are separated and individually corrected to enable temperature correction of an arbitrary patch. Regarding temperature in-plane unevenness correction, a patch temperature unevenness characteristic LUT11511 (temperature in-surface unevenness LUT) is created in the same procedure as in the first embodiment, and temperature in-surface unevenness correction is performed using the LUT. Further, the patch temperature drop amount correction (toner applied amount estimation method) will be described later.

  The printer apparatus according to the present embodiment uses a patch temperature correction unit 15115 having the functional configuration illustrated in FIG. 10 instead of the patch temperature correction unit 115 in the configuration of FIG. In FIG. 10, since the media temperature unevenness characteristic table 11512 is created in the same procedure as the patch temperature unevenness characteristic LUT11511, the description thereof is omitted since it has already been described in the first embodiment. However, in the first embodiment, the temperature in-plane unevenness LUT including the difference in the amount of applied toner is created, but in this embodiment, only the medium is flowed to the transport path without printing the patch, and the temperature in-surface unevenness is detected. Note that the LUT is created.

  First, generation processing of the patch temperature drop amount correction characteristic table 11513 used for correcting the patch temperature drop amount will be described with reference to FIG. 12 showing a flowchart of the process. Note that this processing is performed before product shipment, and is performed using the temperature unevenness measurement system 2 and the printer apparatus 1 outside the printer as shown in FIG.

  First, in step S <b> 1701, a control unit (not shown) of the controller unit 11 in the printer device 1 uses the data of a plurality of patches recorded in a memory (not shown) in the printer device 1 to send the data to the engine unit 12. A plurality of patches are printed on a recording medium. Note that the printing position of each patch on the recording medium is determined in advance. In such printing, a maximum n% (for example, 250%) patch, which is the maximum loading amount, is printed by overlapping each toner of cyan, magenta, yellow, and black at 100% at each printing position. Print.

  In step S1702, the temperature sensor unit 124 connected to the temperature unevenness measurement system 2 shown in FIG. 14 measures the temperature Tm of the printed maximum applied amount n% patch that falls within the sensor measurement range. The temperature sensor unit 124 is installed at a position where the color sensor is installed after product shipment, and measures the temperature on the recording medium at the point where the color sensor unit 123 measures color.

  Next, in step S1703, the temperature sensor unit 124 measures the temperature Tw when the applied toner amount is 0% (that is, paper white) within the sensor measurement range. As described above, the temperature unevenness measurement system 2 creates a relationship between the toner applied amount and the patch temperature as shown in FIG. 13 as a patch temperature drop amount correction characteristic table from the measurement results of the temperature Tm and the temperature Tw.

  FIG. 13 is a diagram illustrating the relationship between the toner loading amount and the patch temperature. The temperature when the applied toner amount = 0% (that is, paper white) is Tw, and the temperature of the patch when the applied toner amount = n% is Tm.

  Next, patch temperature drop correction performed by the patch temperature correction unit 15115, temperature in-plane unevenness correction on the recording medium, and colorimetric values obtained by correcting the colorimetric value variation due to temperature by the colorimetric value temperature correction unit 114 are obtained. The process for obtaining will be described with reference to FIG. 11 showing a flowchart of the process.

  First, in step S1601, the color matching unit 111 receives print data of a patch group having color information expressed in CMYK from the host PC. The color matching unit 111 performs a known adjustment process on the data of each patch included in the print data using the color matching LUT 1111. Then, the color matching unit 111 sends the print position information 1113 of each patch included in the print data to the patch temperature correction unit 115.

  The calibration unit 112 performs a conversion process on each patch adjusted by the color matching unit 111 using the calibration LUT 1121 and fixes each converted patch on the recording medium by the fixing unit 121. Here, the patch to be printed (fixed) is an arbitrary color, and a patch corresponding to the purpose may be printed.

  In step S1602, the temperature sensor unit 122 measures the paper white temperature Tw0 on the recording medium conveyed from the fixing unit 121, and sends the measurement result to the patch temperature correction unit 15115.

  In step S1603, the color sensor unit 123 measures the color of each patch on the recording medium conveyed from the fixing unit 121. Then, the colorimetric value 1231 of each patch is sent to the colorimetric value temperature correction unit 114 as the colorimetric result.

  Next, in step S1604, the correction amount calculation unit 151115 included in the patch temperature correction unit 15115 uses the CMYK values processed by the color matching unit 111 to obtain the patch application amount PQ according to the following (formula 1). Further, the CMYK value indicates blending information of each toner in the patch. If the specific heat per unit amount differs for each toner, the patch loading amount PQ may be obtained using the proportional coefficients a, b, c, d as shown in (Equation 1 ').

Patch loading PQ (%) = C + M + Y + K (Formula 1)
Patch loading PQ (%) = a · C + b · M + c · Y + d · K (Formula 1 ')
Next, the correction temperature Tc is obtained according to the following (Equation 2).

Correction temperature Tc = (Tm−Tw) × PQ / n + Tw0 (Formula 2)
Here, (Tm−Tw) × PQ / n is a correction for the amount of decrease due to the specific heat of the patch in accordance with the printed patch, and is a correction term using the patch temperature decrease amount correction characteristic table 11513. Tw0 is the paper white temperature measured by the temperature sensor unit 122. The above processing is the patch temperature drop amount correction (toner applied amount estimation method). In the subsequent processing, temperature in-plane unevenness correction on the recording medium is performed.

  In step S1605, the patch temperature correction unit 15115 uses the temperature Tw0 (temperature information 1221), the print position information 1113 of each patch, and the media temperature unevenness characteristic table 11512, as in the first embodiment. The patch correction temperature Tc ′ is obtained. Specifically, Tc ′ can be obtained by multiplying (or adding or subtracting) the temperature relative value registered in the media temperature unevenness characteristic table 11512 by Tc obtained above.

  Next, in step S1606, the colorimetric value temperature correction unit 114 sets the colorimetric value of the patch acquired from the color sensor unit 123 to the correction temperature Tc ′ of this patch and the CMYK adjusted by the color matching unit 111 for this patch. And correct the value. Such processing is performed for each patch. Thereby, the colorimetric value of each patch can be corrected using the corresponding correction temperature Tc '.

  After that, the calibration LUT generation unit 113 uses the colorimetric values corrected by the colorimetric value temperature correction unit 114 for each patch and the adjusted CMYK values of each patch by the color matching unit 111, thereby performing the calibration LUT 1121. Process to update. Each of the above embodiments is not limited to an electrophotographic printer apparatus that performs fixing by heating and pressurization, and can be applied to a printer having a mechanism such as UV fixing.

Claims (3)

A printing apparatus that corrects the colorimetric result of a patch printed on a recording medium using the temperature of the patch,
Means for storing in advance a print target patch to be printed at a print position on a recording medium, a relative temperature value of the print target patch with respect to a paper white temperature of the recording medium;
Fixing means for fixing the print target patch to the printing position;
After the fixing, color measuring means for measuring the color of the print target patch fixed at the printing position;
Measuring means for measuring the paper white temperature of the recording medium;
Using the relative temperature value and the paper white temperature measured by the measuring unit, the colorimetric measurement by the colorimetric unit is performed on the basis of the measured paper white temperature of the patch fixed at the printing position. And a calculating means for obtaining a temperature used for correcting the value.   The printing apparatus according to claim 1, wherein the colorimetric value of the print target patch is a Lab value. A printing apparatus for correcting a colorimetric result of a patch printed on a recording medium by using the temperature of the patch, the paper of the recording medium obtained in advance for a printing target patch to be printed at a printing position on the recording medium A control method of a printing apparatus for storing a relative temperature value of a patch to be printed with respect to a white temperature,
A fixing step in which a fixing unit of the printing apparatus fixes the print target patch to the printing position;
A colorimetric step in which the colorimetric means of the printing apparatus performs colorimetry on a print target patch fixed at the printing position after the fixing;
A measuring step in which the measuring means of the printing apparatus measures the paper white temperature of the recording medium;
The calculation means of the printing apparatus uses the relative temperature value and the paper white temperature measured in the measurement step to calculate a temperature based on the measured paper white temperature of the patch fixed at the printing position. And a calculation step for obtaining a temperature used for correcting the colorimetric value in the colorimetry step.

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