JP4403744B2 - Correction data generation apparatus and light quantity correction method for optical print head - Google Patents

Description

  The present invention relates to an image forming apparatus that forms a latent image by performing optical writing on an image carrier, and more particularly to optical writing by a recording head (print head) including a plurality of light emitting elements.

  In image forming apparatuses such as printers, copiers, and facsimiles that employ an electrophotographic method, after obtaining an electrostatic latent image by irradiating image information onto a uniformly charged photoreceptor by optical recording means The electrostatic latent image is visualized by adding toner, and the image is formed by transferring and fixing on the recording paper. As such an optical recording means, in addition to an optical scanning method in which a laser is used to scan and expose a laser beam in the main scanning direction, an LED (Light Emitting Diode) has recently been received in response to a request for downsizing of the apparatus. Optical recording means using LED print heads (LPH: LED Print Head) arranged in large numbers in the main scanning direction is employed.

  The LPH generally has an LED array in which a plurality of LED chips in which a large number of LEDs are arranged in a line are arranged, and a large number of rod lenses for imaging the light output from the LEDs on the surface of the photosensitive member (photosensitive drum). And a selfoc lens in which are arranged. In the image forming apparatus, each LED of the LPH is driven based on input image data, light is output toward the photosensitive member, and light is imaged on the surface of the photosensitive member by the SELFOC lens. An electrostatic latent image is formed in the sub-scanning direction by relatively moving the photoconductor and LPH.

  This LPH has a structure in which a plurality of light emitting elements and lenses are arranged in the main scanning direction, so that variations in the respective light emitting points greatly affect the image quality. In particular, when there is variation in the amount of light emitted from the light emitting points or when the lens characteristics vary, streaks and density unevenness in the sub-scanning direction are generated, and image quality defects are likely to occur. Therefore, as a conventional technique, there is a technique in which a test pattern formed and output on a sheet using LPH is read by a reading unit, and light quantity correction of each LED in the LPH is performed based on the obtained reading result (Patent Document). 1).

Japanese Patent Laid-Open No. 2001-146038 (page 5-7)

  In recent years, colorization has rapidly progressed in image forming apparatuses, and so-called full-color tandem machines have been put into practical use for the purpose of forming color images at high speed and high image quality. As this type of full-color tandem machine, for example, four image forming units of yellow (Y), magenta (M), cyan (C), and black (K) are arranged in parallel to form an intermediate transfer member or recording paper. A toner image formed by each image forming unit is sequentially transferred to form a full color or black and white (monochrome) image.

  However, in Patent Document 1, since uniform light amount correction is performed for all image forming units, even if sufficient light amount correction is performed for some colors, light amount correction is not possible for other colors. Sometimes it was enough. In Patent Document 1, a so-called tandem type image forming apparatus is described as an example. However, this problem can also occur in a so-called four-cycle type image forming apparatus. However, in the case of a tandem type image forming apparatus, when correction is performed with the same correction resolution, the convergence of the correction is poor (the line does not disappear after one correction), and it is necessary to perform corrections many times. In addition, each image forming unit corrects not only the color but also the gradation, but it is sufficient for some gradations only by performing a uniform light amount correction on each gradation. Even if the light amount correction is performed, the light amount correction may be insufficient for other gradations.

The present invention has been made to solve the above technical problem, and an object of the present invention is to perform light amount correction according to color and gradation.
Another object of the present invention is to suppress the occurrence of image defects such as density unevenness.

  The correction data generating apparatus according to the present invention includes a reading unit that reads a test pattern printed by a recording head including a plurality of light emitting elements, a pixel corresponding to each light emitting element and an output value of the test pattern read by the reading unit. A data conversion unit that converts the output data into a relationship, a correction basic data storage unit that stores basic data for correction set for each color and / or gradation, and output data converted by the data conversion unit Based on the correction basic data read from the correction basic data storage unit, the correction data calculation unit that calculates correction data for correcting the light emission amount of each light emitting element, and the correction data calculation unit And an output unit for outputting correction data and writing it in the memory.

  Here, the correction data calculation unit can calculate the correction data based on correction basic data corresponding to the color and / or gradation of the test pattern. Further, the correction basic data storage unit stores correction resolution data determined based on the relationship between the exposure energy of the light emitting element and the density of the image obtained corresponding to the change in the exposure energy as the correction basic data. It can be characterized by that. Furthermore, the data conversion unit can generate density data that is a relationship between a pixel and an image density as output data. In this case, the data conversion unit can create density ratio data obtained by dividing the density of each pixel by the average value of the density of all pixels as density data.

  From another point of view, the image forming apparatus of the present invention includes a print head having a plurality of light emitting elements, a driver for driving the print head, and basic data for correction for each color and / or each gradation. And a writing control unit for controlling the driver based on the correction data obtained originally.

  In this image forming apparatus, a plurality of print heads are provided, and a driver is provided for each print head. Further, the image processing apparatus further includes a memory storing correction basic data, and the writing control unit controls the driver based on the correction data of each color and / or each gradation read from the memory. it can. In this case, the writing control unit reads out correction data in which a pixel corresponding to each light emitting element of the print head is associated with a correction value in the pixel from the memory, and the driver is based on the correction data from the writing control unit. Thus, the writing operation amount of each light emitting element in the print head can be corrected. At this time, the memory may be characterized by storing different correction data for each color and / or gradation.

  Further, from another viewpoint, the present invention is a light amount correction method for an optical print head that corrects the light amount of exposure by a plurality of light emitting elements that form a test pattern by reading a test pattern printed by an image forming apparatus. Reading the test pattern and acquiring the test pattern as image data; converting the acquired image data into density data that is a relationship between the pixel corresponding to each light emitting element and the image density; and And calculating correction data for correcting the amount of light emitted from each light emitting element based on the density data and the basic data for correction for each color and / or gradation.

  Here, the basic data for correction can be characterized in that it is correction resolution data determined based on the relationship between the exposure energy of the light emitting element and the density of the image obtained corresponding to the change in the exposure energy. .

According to the present invention, it is possible to perform light amount correction according to color and gradation.
Further, according to the present invention, it is possible to suppress the occurrence of image defects such as density unevenness.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
—Embodiment 1—
FIG. 1 is a diagram showing an overall configuration of an image forming apparatus using an LED print head, and shows a so-called tandem type digital color printer. An image forming apparatus shown in FIG. 1 includes an image processing system 10 that forms an image corresponding to gradation data of each color, an image output control unit 30 that controls the image processing system 10, such as a personal computer (PC). 2 and an image reading apparatus (IIT) 3 and an image processing unit (IPS: Image Processing System) 40 that performs predetermined image processing on image data received from these.

  The image processing system 10 includes an image forming unit 11 composed of a plurality of engines arranged in parallel at regular intervals in the horizontal direction. The image forming unit 11 includes four image forming units 11Y, 11M, 11C, and 11K of yellow (Y), magenta (M), cyan (C), and black (K). A photoconductor drum 12 that is an image carrier (photoconductor) that forms an image and carries a toner image, a charger 13 that uniformly charges the surface of the photoconductor drum 12, and a photoconductor charged by the charger 13. An LED print head (LPH) 14 which is a print head for exposing the drum 12 and a developing unit 15 for developing a latent image obtained by the LPH 14 are provided. Further, the image process system 10 conveys the recording paper in order to multiplex-transfer the toner images of the respective colors formed on the photosensitive drums 12 of the image forming units 11Y, 11M, 11C, and 11K onto the recording paper. A sheet conveying belt 21, a driving roll 22 which is a roll for driving the sheet conveying belt 21, and a transfer roll 23 for transferring the toner image on the photosensitive drum 12 onto a recording sheet are provided.

  The image forming units 11Y, 11M, 11C, and 11K have substantially the same configuration except for the toner stored in the developing device 15. Image signals input from the PC 2 or IIT 3 are subjected to image processing by the image processing unit 40 and supplied to the image forming units 11Y, 11M, 11C, and 11K through the interface. The image process system 10 operates based on a control signal such as a synchronization signal supplied from the image output control unit 30. First, in the yellow image forming unit 11Y, an electrostatic latent image is formed on the surface of the photosensitive drum 12 charged by the charger 13 by the LPH 14 based on the image signal obtained from the image processing unit 40. A yellow toner image is formed on the electrostatic latent image by the developing unit 15, and the formed yellow toner image is transferred to the recording paper on the paper transport belt 21 that rotates in the direction of the arrow in the figure. It is transcribed using. Similarly, magenta, cyan, and black toner images are formed on the respective photosensitive drums 12 and are multiple-transferred onto the recording paper on the paper transport belt 21 using the transfer roll 23. The multiple transferred toner images on the recording paper are conveyed to the fixing device 24 and fixed on the recording paper by heat and pressure.

  FIG. 2 is a diagram showing a configuration of an LED print head (LPH) 14 that is a recording head or a print head. The LPH 14 is an LED array 51 in which a large number of LEDs are arranged as a light emitting element, a printed circuit board 52 that supports the LED array 51 and controls a drive of the LED array 51, and light emitted from each LED. A SELFOC lens array (SLA) 53 for imaging the beam on the photosensitive drum 12 is provided, and the printed circuit board 52 and the SELFOC lens array 53 are held in a housing 54. The LED array 51 includes LEDs arranged in the number of pixels in the main scanning direction. For example, when an A3 size short (297 mm) is used as the main scanning direction, 7020 LEDs are arranged at intervals of about 42.3 μm at a resolution of 600 dpi. In addition, the arrangement | sequence may be arranged in zigzag form other than the case where it is located in a line.

Next, the light amount correction of the LPH 14 will be described.
FIG. 3 is a diagram for explaining the light amount correction system according to the present embodiment. The correction data generation unit 60 constituting the light amount correction system is connected to the print sample reading device 70 as a reading unit that reads the test pattern on the print sample PS created using the LPH 14, that is, the image forming apparatus according to the present embodiment. Has been. Here, for example, IIT3 can be used as the print sample reading device 70, but in the case of an image forming apparatus such as a printer that does not have IIT3, a dedicated print sample reading device 70 can be used. The correction data generating device 60 receives a read data received by the print sample reading device 70, and density ratio data (each pixel) using the read data received by the read data receiving unit 61 as output data (density data). Density ratio data conversion unit 62 for converting the image density by an average value of the density of all pixels), a correction resolution storage unit 63 in which correction resolution data for each color is stored in advance as basic data for correction, A correction value calculation unit 64 as a correction data calculation unit that calculates a correction value based on the density ratio data from the density ratio data conversion unit 63 and the correction resolution data corresponding to the color from the correction resolution storage unit 63; And a correction value output unit 65 as an output unit that outputs and writes the correction value obtained to the memory 31. The correction data generation device 60 and the print sample reading device 70 constitute a correction data generation device.

  The memory 31 is attached to the image output control unit 30 of the image forming apparatus, and the correction data stored by the writing control unit 32 of the image output control unit 30 is read for each color. ing. Here, an LPH driver 55 as a driver for driving the LED array 51 is attached to each LPH 14 (14Y, 14M, 14C, 14K) of the image forming apparatus. Each LPH driver 55 is driven and controlled by the writing control unit 32 of the image output control unit 30, and each LPH driver 55 stores a table in which correction values and exposure energy are associated with each other. For example, when the current flowing through the LED is corrected, the correction value changes the correction current value as a write operation amount. For example, when correcting the LED driving time, the correction driving time can be changed as the writing operation amount. In the present embodiment, the exposure energy changes by 0.25% per correction value 1.

Next, correction value acquisition processing for each color for the LPH 14 will be described. FIG. 4 is a flowchart for explaining correction value acquisition processing in the present embodiment.
First, an output from the writing control unit 32 is performed, and a constant drive current is supplied from the LPH driver 55 to each LED constituting the LED array 51 of the LPH 14 to form a latent image on the photosensitive drum 12. The latent image is developed with toner, transferred and fixed on a recording sheet, and a test pattern is output (step 101). In this description, the recording paper on which the test pattern is formed is called a print sample PS. In addition, a single color test pattern can be formed on one print sample PS, and four color test patterns can be formed simultaneously. Next, the output pattern of the test pattern formed on the obtained print sample PS is read by the print sample reading device 70 (step 102). Next, the output pattern read by the print sample reading device 70 is input to the read data receiving unit 61 of the correction data generating device 60 and converted into density ratio data by the density ratio data converting unit 62 (step 103). Further, the colors constituting the output pattern obtained based on the image forming position on the print sample PS are determined (step 104). Then, the correction value calculation unit 64 reads correction resolution data corresponding to the colors constituting the output pattern from the correction resolution storage unit 63 (step 105), and reads the read correction resolution data based on the obtained density ratio data. In consideration, a correction value for each pixel is calculated (step 106). Thereafter, the obtained correction value is output to the memory 31 via the correction value output unit 65 and stored (step 107). Repeat this process for all four colors. As a result, different correction values are stored in the memory 31 for each color.
Thereafter, when actually forming an image, the write control unit 32 outputs the correction value stored in the memory 31 together with the write data to each LPH driver 55, and each LPH driver 55 sets the input correction value. Correspondingly, drive control of each LPH 14 is performed while adjusting the exposure energy of each LED.

  Next, a specific example will be described. First, the correction resolution used for calculating the correction value will be described. FIG. 5 shows the relationship between the exposure energy change rate of the LPH 14 in each image forming unit 11 and the density change rate of the image obtained corresponding to this exposure energy change when color is used as a parameter. From the figure, it is understood that even if the exposure energy is changed at the same rate, the degree of density change differs depending on the color. In this embodiment, the density of cyan (C) changes most sensitively to the change in exposure energy (the inclination is large), then yellow (Y), black (K), and magenta (M). ing. This means that in order to obtain the same density change, the exposure energy needs to be changed slightly in the case of cyan (C), whereas for magenta (M), for example, the exposure energy must be changed greatly. Means. For this reason, in the present embodiment, based on the relationship shown in FIG. 5, magenta having the lowest sensitivity (small inclination) is used as a reference, and values normalized for each color are used as correction resolution data. Table 1 shows correction resolution data stored in the correction resolution storage unit 63 of the correction value generation unit 60.

  FIG. 6 shows an example of density ratio data obtained by conversion by the density ratio data converter 62 in step 103. The horizontal axis in FIG. 6 is the LPH pixel number (up to 1000 is shown in the figure), and the vertical axis is the density ratio. The density ratio data is black. It can be seen that there is a large variation between pixels in terms of density before correction. Table 2 shows a list of density ratios in the area A (560th to 574th pixels) in FIG.

Next, correction value calculation in step 106 will be described. Here, since the image color is black as described above, it is determined in step 104 that the color is black, and in step 105, the correction resolution corresponding to black (1.1: see Table 1) is obtained. It is assumed that it has been read out.
In Table 2, for example, the density ratio of the 567th pixel is 0.9624, and the correction resolution corresponding to black is 1.1. Since the minimum unit of the correction value is 0.25% as described above, the correction value of the black 567th pixel is
Correction value = (1−0.9624) /1.1/0.0025
≒ 13.6
≒ 14
Is calculated. Similarly, calculation is performed for other pixels to obtain a black correction value. Table 3 shows correction value calculation results for the black 560th to 574th pixels. The black correction value obtained in this way is stored in the memory 31 in step 107.

  In actual image formation, the black correction value stored in the memory 31 is read by the writing control unit 32 of the image output control unit 30 and transferred to the black LPH 14K, and the light amount correction is performed by the LPH driver 55. Is done. FIG. 7 shows black density ratio data of the print sample PS output after correction. From the figure, it can be seen that the variation is smaller than the density distribution before correction shown in FIG. 6, and a substantially constant density distribution is obtained.

Further, correction values are calculated for yellow (Y), magenta (M), and cyan (C) other than black in the same process as black. Here, cyan will be described as an example. In this description, it is assumed that cyan density ratio distribution data is the same as black (see FIG. 6, Table 2). This can be realized, for example, by mounting the black LED array 51 on the cyan LPH 14.
Next, correction value calculation in step 106 will be described. Here, since the color of the image is cyan as described above, it is determined in step 104 that the color is cyan, and in step 105, the correction resolution (2.2: see Table 1) corresponding to cyan is read. Has been.
In Table 2, for example, the density ratio of the 567th pixel is 0.9624, and the correction resolution corresponding to cyan is 2.2. Since the minimum unit of the correction value is 0.25% as described above, the correction value of the cyan 567th pixel is
Correction value = (1−0.9624) /2.2/0.0025
≒ 6.8
≒ 7
Is calculated. Similarly, other pixels are calculated to obtain a cyan correction value. Table 4 shows correction value calculation results for the 560th to 574th pixels of cyan.

The cyan correction value is smaller in absolute value than the black correction value (see Table 3). This is because the cyan correction resolution value is large, that is, the sensitivity of cyan is higher than that of black (see FIG. 5). The cyan correction value obtained in this way is stored in the memory 31 in step 107.
During actual image formation, the cyan correction value stored in the memory 31 is read by the writing control unit 32 of the image output control unit 30 and transferred to the cyan LPH 14C, and the light amount correction is performed by the LPH driver 55. Is done. FIG. 8 shows the cyan density ratio data of the print sample PS output after correction. As is the case with black, it can be seen that the variation is smaller than the density distribution before correction shown in FIG. 6, and a substantially constant density distribution is obtained.

Here, FIG. 9 shows cyan density ratio data when cyan light amount correction is performed using the black correction values shown in Table 3. In this case, since the cyan light amount correction with high sensitivity is performed using the black correction value with low sensitivity, excessive correction is performed. As a result, it is understood that although the variation is somewhat smaller than the density distribution before correction shown in FIG. 6, the correction is insufficient.
For yellow (Y) and magenta (M), the density of each color is created by creating correction values using correction resolutions corresponding to the respective colors (1.3 for yellow and 1.0 for magenta). It is possible to suppress the variation of.

As described above, in this embodiment, attention is paid to the fact that the relationship between the exposure energy and the density of the obtained image differs for each color, and a different correction value is set for each color. As a result, a substantially constant density distribution can be obtained for each color, and a good image as a whole can be formed.
In the present embodiment, the value of the correction value is changed for each color based on the correction resolution of each color. However, the present invention is not limited to this. For example, the amount of exposure energy changed for each correction value 1 for each color. May be different. In the present embodiment, correction is performed based on density data (density ratio data). However, the present invention is not limited to this. For example, the pixel and brightness obtained by reading the test pattern of the print sample PS Correction may be performed on the basis of the luminance data having the above relationship.

-Embodiment 2-
The present embodiment is substantially the same as the first embodiment, but paying attention to the fact that the relationship between the exposure energy and the obtained image density differs depending on the gradation Cin (Input Coverage) even for the same color. A different correction value is set for each key. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

Next, correction value acquisition processing for each gradation for the LPH 14 will be described. FIG. 10 is a flowchart for explaining correction value acquisition processing in the present embodiment.
First, an output from the writing control unit 32 is performed, and a driving current is supplied to each LED constituting the LED array 51 of the LPH 14 from the LPH driver 55 in a stepwise manner, so that latent images having different gradations are formed on the photosensitive drum 12. The latent image thus formed is developed with toner, transferred and fixed on a recording sheet, and a test pattern is output (step 201). Next, the output pattern of the test pattern formed on the obtained print sample PS is read by the print sample reading device 70 (step 202). Next, the output pattern read by the print sample reading device 70 is input to the read data receiving unit 61 of the correction data generating device 60 and converted into density ratio data by the density ratio data converting unit 62 (step 203). Further, the gradation of the output pattern obtained based on the image forming position on the print sample PS is determined (step 204). Then, the correction value calculation unit 64 reads correction resolution data corresponding to the gradation of the output pattern from the correction resolution storage unit 63 (step 205), and takes the read correction resolution data into account based on the obtained density ratio data. Then, a correction value for each pixel is calculated (step 206). Thereafter, the obtained correction value is output to the memory 31 via the correction value output unit 65 and stored (step 207). This process is performed for each preset gradation (for example, every 10%). As a result, the memory 31 stores different correction values for each gradation.
When actually forming an image, the write control unit 32 outputs the correction value stored in the memory 31 together with the write data to each LPH driver 55, and each LPH driver 55 sets the input correction value to the correction value. Correspondingly, drive control of each LPH 14 is performed while adjusting the exposure energy of each LED.

  Here, FIG. 11 shows the relationship between the exposure energy change rate of the LPH 14 in each image forming unit 11 when the gradation is used as a parameter, and the density change rate of the image obtained corresponding to this exposure energy change. Yes. FIG. 11 illustrates magenta 50% gradation and 20% gradation. From the figure, it is understood that the degree of density change differs depending on the gradation even if the exposure energy is changed at the same rate. In the present embodiment, the slope at 20% gradation is larger than the slope at 50% gradation. For this reason, in the present embodiment, based on the relationship shown in FIG. 11, the 100% gradation with the lowest sensitivity (small slope) is used as a reference, and the normalized value for each gradation (for example, in increments of 10%) is used as the correction resolution. It is said.

  In this embodiment, as a result of setting correction values for each gradation in addition to each color described in Embodiment 1, a substantially constant density distribution can be obtained for each color, and also for each gradation. A substantially constant density distribution can be obtained for each color, and an even better image can be formed.

1 is a diagram illustrating an overall configuration of an image forming apparatus. It is a figure which shows the structure of LPH. It is a figure which shows the light quantity correction system of LPH of each image forming unit. It is a flowchart for demonstrating the correction value acquisition process for every color of LPH. FIG. 5 is a graph showing a relationship between an LPH exposure energy change rate in each image forming unit and a density change rate of an image obtained corresponding to the exposure energy change when color is used as a parameter. It is a figure which shows an example of the density ratio distribution data obtained by converting in the density ratio data converter. It is a figure which shows the density ratio distribution data of black after performing correction. It is a figure which shows the density ratio distribution data of cyan after performing correction. It is a figure which shows the density ratio distribution data of cyan in the case of performing cyan light quantity correction using a black correction value. It is a flowchart for demonstrating the correction value acquisition process for every gradation of LPH. FIG. 6 is a graph showing a relationship between an LPH exposure energy change rate in each image forming unit and a density change rate of an image obtained corresponding to the exposure energy change when gradation is used as a parameter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Main body, 2 ... Personal computer (PC), 3 ... Image reader (IIT), 10 ... Image process system, 11 (11Y, 11M, 11C, 11K) ... Image forming unit, 12 ... Photosensitive drum, 13 ... Charger, 14 (14Y, 14M, 14C, 14K) ... LED print head (LPH), 15 ... developer, 21 ... paper transport belt, 22 ... drive roll, 23 ... transfer roll, 24 ... fixer, 30 ... image Output control unit 31 ... Memory 32 ... Write control unit 40 ... Image processing unit (IPS) 51 ... LED array 52 ... Printed circuit board 53 ... Selfoc lens array (SLA) 54 ... Housing 55... LPH driver 60. Correction value generating unit 61... Reading data receiving unit 62... Density ratio data converting unit 63... Correction resolution storage unit 64. Output unit, 70... Print sample reading device

Claims (6)

A reading unit that reads a monochromatic image printed using a recording head having a plurality of light emitting elements that form pixels by emitting light; and
Output data creation for creating output data that associates the relationship between each pixel formed by the plurality of light emitting elements and the image density at each pixel based on the result obtained by reading the image by the reading unit And
Correction that stores a predetermined correction resolution for each color of the image based on the relationship between the change rate of the exposure energy of the light emitting element that emits light and the change rate of the image density of the pixel that is formed by the light emitting element that emits light A resolution storage;
Based on the output data created by the output data creation unit and the correction resolution corresponding to the color of the image read from the correction resolution storage unit, the amount of light emitted from each of the plurality of light emitting elements is corrected. A correction data calculation unit for calculating correction data for
A correction data generation device including an output unit that outputs the correction data calculated by the correction data calculation unit to write to the memory. The reading unit reads a yellow, magenta, cyan or black image printed using the recording head,
2. The correction data generation apparatus according to claim 1, wherein the correction resolution storage unit stores correction resolutions having different sizes for yellow, magenta, cyan, and black colors.   The correction resolution storage unit stores a correction resolution in which a cyan value is set to be the largest among yellow, magenta, cyan, and black, and a magenta value is set to be the smallest. 2. The correction data generation device according to 2. Reading a monochromatic image printed using an optical print head having a plurality of light emitting elements that form pixels by emitting light; and
Based on the result obtained by reading the image, creating output data in which each pixel formed by the plurality of light emitting elements and the density of the image in each pixel are associated with each other;
A predetermined correction for each color of the image based on the relationship between the output data, the change rate of the exposure energy of the light emitting element that emits light, and the change rate of the image density of the pixel that is formed by the light emitting element that emits light Calculating correction data for correcting the amount of emitted light in each of the plurality of light emitting elements using the resolution; and
And a step of outputting the calculated correction data for writing to a memory. In the reading step, a yellow, magenta, cyan or black image printed using the optical print head is read;
5. The light quantity correction method for an optical print head according to claim 4, wherein in the calculating step, the correction data is calculated using correction resolutions having different sizes for yellow, magenta, cyan, and black colors. 6. The light according to claim 5, wherein the calculating step uses a correction resolution in which the cyan value is set to the largest among yellow, magenta, cyan, and black and the magenta value is set to the smallest. Light quantity correction method for the print head.

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