JP2014076656A - Light amount adjustment method for print head, image forming device, and manufacturing method for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light amount adjustment method for a print head capable of improving quality of an output image.SOLUTION: The light amount adjustment method for a print head includes : a step S1 for forming, on a recording sheet conveyed in the X axis direction, first and second patterns next to each other in an X axis direction using the print head; a step S5 for acquiring first brightness information of a pattern for acquisition of the first brightness information; a step S7 for acquiring second brightness information of a pattern for acquisition of the second brightness information; a step S9 for, on the basis of an emitting part corresponding to a reference pattern and the reference pattern, associating an emitting part corresponding to the pattern for acquisition of the first brightness information with each position, in a Y axis direction, of the pattern for acquisition of the first brightness information; a step S13 for, on the basis of the first brightness information, adjusting an emission light amount of an emitting part corresponding to each position, in the Y axis direction, of the pattern for acquisition of the first brightness information; and a step S15 for, on the basis of the second brightness information, adjusting an emission light amount of an emitting part corresponding to each position, in the Y axis direction, of the reference pattern.

Description

  The present invention relates to a light amount adjusting method for a print head, an image forming apparatus, and a method for manufacturing the image forming apparatus, and more specifically, a light amount adjusting method for a print head having a plurality of light emitting units, the print head and the image carrier. And an image forming apparatus manufacturing method.

  Conventionally, a light amount correction method for a print head having a plurality of light emitting units arranged in a uniaxial direction is known (see, for example, Patent Document 1).

  In this light quantity adjustment method, a lightness information acquisition pattern for acquiring lightness information is formed by irradiating light from a plurality of light emitting units onto a recording medium conveyed in a direction orthogonal to the uniaxial direction. A reference pattern used for associating a plurality of light emitting units (LEDs) with a plurality of positions in the uniaxial direction of the brightness information acquisition pattern is formed outside the brightness information acquisition pattern. Then, based on the brightness information at a plurality of positions in the uniaxial direction of the brightness information acquisition pattern, the light emission amounts of the plurality of light emitting units corresponding to the plurality of positions are adjusted.

  However, the light amount correction method disclosed in Patent Document 1 cannot accurately adjust the light emission amount of a plurality of light emitting units, and improves the quality of an image (output image) formed on a recording medium. Was difficult.

  The present invention relates to a light amount adjustment method for a print head having a plurality of light emitting units, wherein the plurality of light emitting units are arranged so that positions in a uniaxial direction are different from each other, and are conveyed in a direction orthogonal to the uniaxial direction. The first lightness information acquisition pattern and the first pattern including the reference pattern located inside the first lightness information acquisition pattern and the second lightness information acquisition are recorded on the recording medium using the print head. A pattern forming step of forming a second pattern including a pattern in a direction orthogonal to the uniaxial direction, and a first luminosity information at each position in the uniaxial direction of the first luminosity information acquisition pattern Second brightness information at a position corresponding to at least the position of the reference pattern in the uniaxial direction of the brightness information acquisition step and the second brightness information acquisition pattern; Second lightness information acquisition step, and the first lightness information acquisition pattern of the plurality of light emitting units based on the light emitting unit and the reference pattern corresponding to the reference pattern of the plurality of light emitting units. Based on the first brightness information, the first association step of associating the corresponding light emitting section with each position in the uniaxial direction of the first lightness information acquisition pattern, and the first of the plurality of light emitting sections. A first light emission amount adjustment step of adjusting a light emission amount of the light emission unit corresponding to each position in the one-axis direction of the one lightness information acquisition pattern, and at least of the plurality of light emission units based on the second lightness information A second light emission amount adjustment step of adjusting a light emission amount of the light emitting unit corresponding to the position in the uniaxial direction of the reference pattern.

  According to the present invention, the quality of an output image can be improved.

1 is a diagram illustrating a schematic configuration of a laser printer according to an embodiment of the present invention. FIG. 3 is a first diagram for explaining a print head; FIG. 6 is a second diagram for explaining the print head; It is a block diagram which shows the structure of control of a laser printer. 4 is a flowchart illustrating a procedure for adjusting the light amount of a print head. It is a plan view of a recording paper on which a pattern P is formed. 3 is a schematic diagram of a pattern P. FIG. FIG. 8A is a graph showing the brightness of each pixel column of the first pattern P1, and FIG. 8B is a graph showing the brightness of each pixel column of the second pattern P2. It is a graph which shows the relationship between emitted light quantity and brightness. FIG. 10A is a diagram showing a pattern including a reference pattern and brightness information acquisition pattern of the first modification (part 1), and FIG. 10B is a reference pattern of the first modification (part 2). It is a figure which shows the pattern containing the pattern for lightness information acquisition. FIG. 11A is a diagram showing a pattern including a reference pattern and brightness information acquisition pattern of the second modification (part 1), and FIG. 11B is a reference pattern of the second modification (part 2). It is a figure which shows the pattern containing the pattern for lightness information acquisition. FIG. 12A is a diagram showing a pattern including a reference pattern and brightness information acquisition pattern of the third modification (part 1), and FIG. 12B is a reference pattern of the third modification (part 2). It is a figure which shows the pattern containing the pattern for lightness information acquisition. FIG. 13A is a diagram showing a pattern P ′ of the fourth modified example, and FIG. 13B is a diagram showing a pattern P ″ of the fifth modified example. It is a top view of the recording paper in which pattern P '' 'of the 5th modification was formed. It is a figure for demonstrating schematic structure of the color printer which concerns on other embodiment of this invention. FIG. 2 is a perspective view illustrating a schematic configuration of a print head included in the color printer. It is a figure for demonstrating the organic electroluminescent apparatus which the print head of FIG. 16 has. 17 is a flowchart for explaining an example of a light amount adjustment method of the print head of FIG. 16. FIG. 6 is a plan view of a recording paper on which a pattern Q is formed. 20A is an enlarged view of an A portion of the pattern Q, FIG. 20B is an enlarged view of a B portion of the pattern Q, and FIG. 20C is an enlarged view of a C portion of the pattern Q. FIG. It is an enlarged view of the D section of the pattern Q. 22A is a graph showing brightness information in the Y-axis direction of a part of the second pattern Q2, and FIG. 22B is brightness information in the Y-axis direction of a part of the first pattern Q1. It is a graph which shows. It is a graph which shows the brightness information of the Y-axis direction of a part of 3rd pattern Q3. FIG. 24A is a graph showing enlarged brightness information of the end portion on the −Y side of the first or second pattern Q1 or Q2, and FIG. 24B shows the first or third pattern. It is a graph which expands and shows the brightness information of the center of the Y-axis direction of pattern Q1, Q3. FIG. 25A is a graph showing the relationship between the light emission amount of the organic EL element and the brightness of the image, and FIG. 25B shows a test pattern having a plurality of lightness regions corresponding to the plurality of light emission amounts. FIG. FIGS. 26A to 26D are diagrams (No. 1 to No. 4) showing four specific examples of the reference image (pattern). It is a table | surface which shows the generation amount of a vertical stripe with respect to the combination of four reference images and four corrected images. FIG. 6 is a plan view of a recording paper on which a pattern R is formed. FIG. 17 is a flowchart for explaining another example of the light amount adjustment method of the print head of FIG. 16. FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of a laser printer 1000 as an image forming apparatus according to an embodiment of the present invention.

  The laser printer 1000 includes a light source device 1010, a photosensitive drum 1030, a charging charger 1031, a developing roller 1032, a transfer charger 1033, a charge eliminating unit 1034, a cleaning unit 1035, a toner cartridge 1036, a paper feeding roller 1037, a paper feeding tray 1038, a resist. A roller pair 1039, a fixing roller 1041, a paper discharge roller 1042, a paper discharge tray 1043, a communication control device 1050, and a printer control device 1060 that comprehensively controls each of the above parts are provided. These are housed in predetermined positions in the printer housing 1044. Hereinafter, an XYZ three-dimensional orthogonal coordinate system having the longitudinal direction of the photosensitive drum 1030 as the Y-axis direction as shown in FIG. 1 will be described.

  The communication control device 1050 controls bidirectional communication with a host device (for example, a personal computer) via a network or the like.

  The photosensitive drum 1030 is a cylindrical member, and a photosensitive layer is formed on the surface thereof. That is, the surface of the photoconductor drum 1030 is a scanned surface. The photosensitive drum 1030 rotates in the direction of the arrow in FIG.

  The charging charger 1031, the developing roller 1032, the transfer charger 1033, the charge removal unit 1034, and the cleaning unit 1035 are each disposed in the vicinity of the surface of the photosensitive drum 1030. Then, along the rotation direction of the photosensitive drum 1030, the charging charger 1031 → the developing roller 1032 → the transfer charger 1033 → the discharging unit 1034 → the cleaning unit 1035 are arranged in this order.

  The charging charger 1031 uniformly charges the surface of the photosensitive drum 1030.

  The light source device 1010 irradiates the surface of the photosensitive drum 1030 charged by the charging charger 1031 with a light beam modulated based on image information from the host device. As a result, a latent image corresponding to the image information is formed on the surface of the photosensitive drum 1030. The latent image formed here moves in the direction of the developing roller 1032 as the photosensitive drum 1030 rotates. The configuration of the light source device 1010 will be described later.

  The toner cartridge 1036 stores toner, and the toner is supplied to the developing roller 1032.

  The developing roller 1032 causes the toner supplied from the toner cartridge 1036 to adhere to the latent image formed on the surface of the photosensitive drum 1030 to visualize the image information. Here, the latent image to which the toner is attached (hereinafter also referred to as “toner image” for the sake of convenience) moves in the direction of the transfer charger 1033 as the photosensitive drum 1030 rotates.

  Recording paper W is stored in the paper feed tray 1038. A paper feed roller 1037 is disposed in the vicinity of the paper feed tray 1038, and the paper feed roller 1037 takes out the recording paper W one by one from the paper feed tray 1038 and conveys it to the registration roller pair 1039. The registration roller pair 1039 temporarily holds the recording paper W taken out by the paper supply roller 1037, and in the gap between the photosensitive drum 1030 and the transfer charger 1033 according to the rotation of the photosensitive drum 1030. Send it out.

  A voltage having a polarity opposite to that of the toner is applied to the transfer charger 1033 in order to electrically attract the toner on the surface of the photosensitive drum 1030 to the recording paper W. With this voltage, the toner image on the surface of the photosensitive drum 1030 is transferred to the recording paper W. The recording sheet W transferred here is sent to the fixing roller 1041.

  In the fixing roller 1041, heat and pressure are applied to the recording paper W, whereby the toner is fixed on the recording paper W. The recording paper W fixed here is sent to the paper discharge tray 1043 via the paper discharge roller 1042 and is sequentially stacked on the paper discharge tray 1043.

  As can be seen from FIG. 1, the conveyance direction of the recording paper W from the paper feed tray 1038 toward the paper discharge tray 1043 is the −X direction.

  The neutralization unit 1034 neutralizes the surface of the photosensitive drum 1030.

  The cleaning unit 1035 removes the toner remaining on the surface of the photosensitive drum 1030 (residual toner). The surface of the photosensitive drum 1030 from which the residual toner has been removed returns to the position facing the charging charger 1031 again.

  Next, the configuration of the light source device 1010 will be described.

  As an example, the light source device 1010 includes a print head 2200, a control device 3022 (see FIG. 4), and the like. These are attached to an optical housing (not shown).

  As an example, the print head 2200 is disposed on the + Z side of the photosensitive drum 1030.

  2 and 3, the print head 2200 includes, as an example, an LED array 2202 including a plurality of LEDs (light emitting diodes) arranged one-dimensionally, a substrate 2203, and a plurality of rod lenses RL arranged one-dimensionally. A rod lens array 2204 including a (refractive index distribution type lens), a holding member 2206 made of a plate-like member parallel to the XY plane, a package member 2208 made of a cylindrical member extending in the Z-axis direction, and the like.

  The LED array 2202 is mounted on the −Z side surface of the substrate 2203 so that the arrangement direction of the plurality of LEDs is the Y-axis direction. The emission direction of each LED of the LED array 2202 is the −Z direction. The substrate 2203 is attached to the −Z side surface of the holding member 2206 so as to be parallel to the XY plane. The holding member 2206 is fixed to the + Z side surface of the package member 2208 in parallel to the XY plane.

  The LED array 2202 emits a plurality of lights arranged in the Y-axis direction to the −Z side. Each LED of the LED array 2202 corresponds to one pixel.

  The rod lens array 2204 is fitted on the inner peripheral side of the package member 2208 so that the arrangement direction of the plurality of rod lenses RL is the Y-axis direction. That is, the rod lens array 2204 is arranged on the −Z side of the LED array 2202. The plurality of rod lenses RL individually correspond to the plurality of LEDs, and are disposed on the optical paths of the plurality of lights from the corresponding plurality of LEDs.

  The light from each LED of the print head 2200 configured as described above is condensed on the corresponding photosensitive drum by the corresponding rod lens RL to form a light spot. That is, a conjugate image of each LED of the corresponding LED array 2202 is formed on the surface of each photosensitive drum.

  As illustrated in FIG. 4 as an example, the control device 3022 includes a CPU 3210, a flash memory 3211, a RAM 3212, an IF (interface) 3214, a pixel clock generation circuit 3215, an image processing circuit 3216, a write control circuit 3219, and a light amount adjustment circuit 3223. A light source driving circuit 3221 and the like. Note that the arrows in FIG. 4 indicate the flow of typical signals and information, and do not represent the entire connection relationship of each block.

  The pixel clock generation circuit 3215 generates a pixel clock signal. The pixel clock signal can be phase-modulated with a resolution of 1/8 clock.

  The image processing circuit 3216 performs predetermined halftone processing on the image data raster-developed for each color by the CPU 3210, and then creates dot data for each LED of each print head.

  The write control circuit 3219 starts writing at a predetermined timing for each station. Then, the dot data of each LED is superimposed on the pixel clock signal from the pixel clock generation circuit 3215 in accordance with the writing start timing, and independent modulation data is generated for each LED.

  As will be described in detail later, the light amount adjustment circuit 3223 adjusts the light emission amount of each LED of the print head 2200 based on the light amount correction data stored in the flash memory 3211 and notifies the light source drive circuit 3221 of the adjustment result. .

  The light source drive circuit 3221 outputs a drive signal corresponding to the modulation data from the write control circuit 3219 and the adjustment result from the light amount adjustment circuit 3223 to each LED of the print head 2200.

  An IF (interface) 3214 is a communication interface that controls bidirectional communication with the printer control apparatus 1060.

  The flash memory 3211 stores various programs described in codes readable by the CPU 3210 and various data necessary for executing the programs.

  The RAM 3212 is a working memory.

  The CPU 3210 operates according to a program stored in the flash memory 3211 and controls the entire light source device 1010.

  Here, an image formed on the recording paper W when the amount of light emitted from the print head 2200 varies due to, for example, individual differences between the plurality of LEDs and variations in the optical characteristics of the plurality of rod lenses. Density unevenness (vertical stripes) occurs in (output image).

  Therefore, in the present embodiment, the amount of light of the print head 2200 is adjusted in order to suppress the occurrence of density unevenness in the output image.

  Below, an example of the light quantity adjustment method of the print head 2200 is demonstrated, referring the flowchart of FIG. For example, the light amount adjustment of the print head 2200 is performed by an operator when the laser printer 1000 is manufactured.

  First, in the first step S1, as shown in FIG. 6, as an example, the first pattern P1 including the first reference pattern 100 and the first brightness information acquisition pattern 150, the second reference pattern 200, and the second The second pattern P2 including the brightness information acquisition pattern 250 is formed on the recording paper W.

  Here, as an example, the first pattern P1 is formed in an area downstream (−X side) in the conveyance direction of the recording paper W, and the second pattern P2 is upstream in the conveyance direction (+ X side) of the recording paper W. ). The first and second patterns P1 and P2 are integrated in series, and constitute one pattern P as a whole. In the following, for convenience, the number of pixels constituting the pattern P is made smaller than the actual number.

  The pattern P is formed by a process similar to the series of image forming processes by the laser printer 1000 described above. That is, light modulated based on the image information of the pattern P from the print head 2200 is applied to the surface of the photosensitive drum 1030, and a latent image is formed on the surface. The latent image is developed by the developing roller 1032, and the developed image is transferred to the recording paper W by the transfer charger 1033 and then fixed by the fixing device 1040. Note that the image information of the pattern P is stored in the flash memory 3211 in advance.

  Here, as an example, the resolution of the print head 2200 is set to 1200 dpi (dots per inch), and the pattern P is formed on the recording paper W at a resolution of 1200 dpi.

  The pattern P includes a plurality of (for example, 48) pixels arranged in the X-axis direction, and includes a plurality of (for example, 24) pixel rows arranged in the Y-axis direction. Among a plurality of (for example, 1152) pixels constituting the pattern P, the black pixel is formed by supplying the same current to the corresponding LED.

  As an example, the first and second reference patterns 100 and 200 have substantially the same configuration except that the arrangement is different. Specifically, each of the first and second reference patterns 100 and 200 is, for example, an elongated line pattern extending in the conveyance direction (X-axis direction) of the recording paper W, and orthogonal to the conveyance direction of the recording paper W. Formed in the vicinity of the center of the recording paper W in the Y-axis direction so that the positions in the recording direction (Y-axis direction) are different from each other. Hereinafter, the first and second reference patterns 100 and 200 are collectively referred to as a reference pattern when they are not distinguished from each other.

  More specifically, as an example, the reference pattern has a longitudinal direction in the X-axis direction composed of 96 pixels arranged in a matrix of 24 rows in the X-axis direction and 4 columns in the Y-axis direction at a resolution of 1200 dpi. It is a rectangular pattern. As an example, the reference pattern is formed by constantly turning off four LEDs located near the center in the Y-axis direction among the plurality of LEDs of the print head 2200. That is, the reference pattern is an elongated white line pattern extending in the X-axis direction (see FIG. 7). Note that the reference pattern may be a black line pattern extending in the X-axis direction, which is formed when the corresponding four LEDs are always lit.

  The first and second brightness information acquisition patterns 150 and 250 have substantially the same configuration except that the arrangement is different. That is, the first and second patterns P1 and P2 have substantially the same configuration except for the position of the reference pattern. Hereinafter, the first and second lightness information acquisition patterns 150 and 250 are collectively referred to as lightness information acquisition patterns unless they are distinguished from each other.

  As an example, the lightness information acquisition pattern includes a plurality of checker patterns CP1 and CP2 each including a plurality of square patterns arranged in a staggered manner and sandwiching a reference pattern in the Y-axis direction. That is, the brightness information acquisition pattern is divided into two regions (two checker patterns CP1 and CP2) by the reference pattern. In other words, the reference pattern is located inside the brightness information acquisition pattern.

  The lightness information acquisition pattern can be said to be a halftone uniform pattern with an image area ratio (ratio of black pixels in all pixels) of 50% (see FIG. 7). More specifically, the image area ratio of each pixel column constituting the brightness information acquisition pattern, that is, the ratio of black pixels to all the pixels in the pixel column is set to be equal to each other. In other words, in each pixel column of the brightness information acquisition pattern, the ratio of black pixels to white pixels is set to 1: 1.

  As an example, each square pattern is a square pattern composed of 16 pixels arranged in a matrix of 4 rows in the X-axis direction and 4 rows in the Y-axis direction. The LED is formed by turning on or off for the conveyance time of four pixels of the recording paper W.

  Each checker pattern includes four LEDs adjacent in the Y-axis direction, and a plurality of LED groups adjacent in the Y-axis direction are alternately turned on or off every other LED group.

  The recording paper W is discharged to the paper discharge tray 1043 after the pattern P is fixed by the fixing device 1040.

  In the next step S3, the first and second patterns P1 and P2 are read by the scanner 1085. Specifically, the recording paper W discharged to the paper discharge tray 1043 is set and scanned by the operator in the scanner 1085 so that the arrangement direction of the first and second patterns P1 and P2 is the X-axis direction. The As an example, the reading resolution of the scanner 1085 is 1200 dpi, which is the same as the resolution of the print head 2200. The image information of the first and second patterns P1 and P2 read by the scanner 1085 is sent to the brightness measuring device 2500.

  In the next step S <b> 5, first brightness information in each pixel column of the first brightness information acquisition pattern 150 is acquired.

  Specifically, first, the brightness measuring device 2500 measures the brightness information of the first pattern P1 in pixel units (resolution 1200 dpi). Next, the brightness information of the first pattern P1 is averaged in the X-axis direction. That is, the average value of the brightness information of a plurality of pixels arranged in the X-axis direction of each of the plurality of pixel columns of the first pattern P1 is obtained, and the average value is acquired as the first brightness information of the pixel column.

  In FIG. 8A, the first brightness information of each pixel column of the first pattern P1 acquired by the brightness measuring device 2500 is shown in a graph. From FIG. 8A, the brightness of the four pixel columns constituting the first reference pattern 100 is significantly higher than the brightness of the twenty pixel columns constituting the first brightness information acquisition pattern 150. I understand. As a result, the position in the Y-axis direction (hereinafter referred to as the Y position) of each pixel column of the first reference pattern 100 can be substantially specified.

  In the next step S <b> 7, second brightness information in each pixel column of the second brightness information acquisition pattern 250 is acquired.

  Specifically, the brightness measuring device 2500 measures the brightness information of the second pattern P2 in units of pixels (resolution 1200 dpi). Then, the brightness information of the second pattern P2 is averaged in the X-axis direction. That is, the average value of the brightness information of a plurality of pixels arranged in the X-axis direction of each of the plurality of pixel columns of the second pattern P2 is obtained, and the average value is acquired as the second brightness information of the pixel column.

  In FIG. 8B, the second brightness information of each pixel column of the second pattern P2 obtained by the brightness measuring device 2500 is shown in a graph. From FIG. 8B, the brightness of the four pixel columns constituting the second reference pattern 200 is significantly higher than the brightness of the twenty pixel columns constituting the second brightness information acquisition pattern 250. I understand. As a result, the Y positions of the four pixel columns of the second reference pattern 200 can be roughly specified.

  In the next step S9, with reference to the four pixel columns of the first reference pattern 100 and the four LEDs corresponding to the first reference pattern 100, the twenty pixel columns of the first brightness information acquisition pattern 150, Twenty LEDs corresponding to one lightness information acquisition pattern 150 are individually associated with each other.

  Specifically, as an example, the LED numbers of four LEDs corresponding to the first reference pattern 100 are 13 to 16. The Y positions of these four LEDs are 0.2752 mm (≈13 × 25.4 / 1200), 0.2963 (≈14 × 25.4 / 1200), and 0.3175 (= 15 × 25.4 /), respectively. 1200) and 0.3387 mm (≈16 × 25.4 / 1200). The average value of these four values is approximately 0.3069 mm. Similarly, the Y positions of 20 LEDs (LED numbers 1 to 13 and 18 to 24) corresponding to the first lightness information acquisition pattern 150 can be obtained.

  Accordingly, for example, if the average Y position in the Y-axis direction of the lightness peak in FIG. 8A is set to the above average value of 0.3069 mm, the 20 lightness information acquisition patterns 150 in the same manner as described above are used. The Y position of the pixel column can be obtained.

  Then, based on the correspondence between the Y positions of the 20 LEDs corresponding to the first lightness information acquisition pattern 150 and the Y positions of the 20 pixel columns of the first lightness information acquisition pattern 150, the first lightness The 20 pixel columns of the information acquisition pattern 150 can be individually associated with the 20 LEDs corresponding to the first brightness information acquisition pattern 150.

  In the next step S <b> 11, 4 of the first reference pattern 100 of the second lightness information acquisition pattern 250 with reference to the four pixel columns of the second reference pattern 200 and the four LEDs corresponding to the second reference pattern 200. Four pixel columns corresponding to one pixel column and four LEDs of the first reference pattern 100 are individually associated with each other.

  Specifically, as an example, the LED numbers of four LEDs corresponding to the second reference pattern 200 are 9-12. The Y positions of these four LEDs are 0.1905 mm (= 9 × 25.4 / 1200), 0.2117 (≈10 × 25.4 / 1200), 0.2328 (≈11 × 25.4 /), respectively. 1200) and 0.254 mm (= 12 × 25.4 / 1200). The average value of these four values is approximately 0.2223 mm. Similarly, the Y positions of the 20 LEDs (LED numbers 1 to 8 and 13 to 24) corresponding to the second lightness information acquisition pattern 250 can be obtained.

  Accordingly, for example, if the average Y position in the Y-axis direction of the lightness peak in FIG. 8B is set to the above average value of 0.2223 mm, the first lightness information acquisition pattern 250 of the second lightness information acquisition pattern 250 is similar to the above. The Y positions of the four pixel columns corresponding to the four pixel columns of the reference pattern 100 can be obtained.

  Then, the Y position of the four pixel columns corresponding to the four pixel columns of the first reference pattern 100 and the four LEDs corresponding to the four pixel columns of the first reference pattern 100 in the second brightness information acquisition pattern 250. 4 pixel columns corresponding to the four pixel columns of the first reference pattern 100 and the four pixel columns of the first reference pattern 100 of the second lightness information acquisition pattern 250 based on the correspondence relationship with the Y position of The four LEDs corresponding to can be individually associated with each other.

  In the next step S13, the 20 pixel columns of the first lightness information acquisition pattern 150 are based on the 20 first lightness information that is the lightness information of the 20 pixel columns of the first lightness information acquisition pattern 150. The amount of light emitted by 20 LEDs individually corresponding to each is adjusted.

  In the next step S15, based on the four second lightness information that is the lightness information of the four pixel columns corresponding to the four pixel columns of the first reference pattern 100 in the second lightness information acquisition pattern 250, The light emission amounts of the four LEDs individually corresponding to the four pixel columns of one reference pattern 100 are adjusted.

  Specifically, based on the relationship (see FIG. 9) between the change in light emission amount of the LED and the change in brightness obtained in advance by the light quantity correction data calculation circuit 3500, for example, 20 of the first brightness information acquisition pattern 150. The print head so that the brightness information of the four pixel columns individually corresponding to the four pixel columns of the first reference pattern 100 in the second brightness information acquisition pattern 250 is uniform. Light amount correction data for correcting the light amount of 2200 is calculated, and the calculation result is stored in the flash memory 3211.

  The relationship between the change in the amount of light emitted from the LED and the change in lightness can be obtained by changing the amount of light emitted from the LED in advance and reading the image formed on the recording paper with a scanner and measuring the lightness information of the read image.

  A method for calculating the light amount correction data will be briefly described below. As an example, it is assumed that there is a relationship (light amount correction coefficient −3) that reduces the light emission amount of the LED by 3% in order to change the brightness by one (see FIG. 7). As an example, a total of 24 pixel columns including 20 pixel columns of the first lightness information acquisition pattern 150 and four pixel columns corresponding to the first reference pattern 100 in the second lightness information acquisition pattern 250. In order to change the lightness from 49 to 50 when the first lightness information acquisition pattern 150 has a pixel array with lightness 49 and a pixel array with lightness 51, the lightness average is 50 pixels. The light emission amount of the LED corresponding to the column may be reduced by 3%, and in order to change the lightness from 51 to 50, the light emission amount of the LED corresponding to the pixel column of lightness 51 may be increased by 3%. Similarly, the adjustment of the light emission amounts of the four LEDs corresponding to the first reference pattern 100 is performed so that the brightness of the four pixel columns corresponding to the first reference pattern 100 in the second brightness information acquisition pattern 250 is 50. Just do it. Here, the adjustment of the light emission quantity of each LED is performed by changing the magnitude of the current supplied to each LED as an example.

  That is, the average brightness (for example, 50) of all 24 pixel columns and the brightness information of each pixel column of the first brightness information acquisition pattern 150 or the first reference pattern 100 of the second brightness information acquisition pattern 250 A value obtained by multiplying the difference between the brightness information of each corresponding pixel column and the light amount correction coefficient −3 may be used as correction data for the light emission amount of the LED corresponding to the pixel column (see Table 1).

  In Table 1, as an example, the brightness of the five pixel columns corresponding to the five LEDs of LED numbers 8 to 12 in the first brightness information acquisition pattern 150, the difference A between the brightness and the average brightness, and A light amount correction coefficient B and correction data (A × B) are shown.

  Data including correction data for each LED calculated as described above is light amount correction data for the print head 2200.

  For example, when there is a print request from the host device such as a personal computer to the laser printer 1000, the light amount correction data stored in the flash memory 3211 is sent to the light amount adjustment circuit 3223, and the light amount adjustment circuit 3223 is based on the light amount correction data. The light emission amount of each LED is adjusted, and the adjustment result is sent to the light source drive circuit 3221. The light source drive circuit 3221 outputs a drive signal corresponding to the modulation data from the write control circuit 3219 and the adjustment result from the light amount adjustment circuit 3223 to the LED.

  As described above, the light amount correction data of the print head 2200 is created and stored, and when printing is performed, the light amount of the print head 2200 is adjusted using the light amount correction data.

  Note that the above-described creation and storage of the light amount correction data of the print head 2200 may be appropriately performed by an operator, a serviceman, or a user via an operation unit, for example, temperature, humidity, the number of times of printing, and the like. It may be automatically performed based on a regular basis.

  The light amount adjustment method of the present embodiment described above uses the print head 2200 to acquire the first lightness information on the recording paper W transported in the X-axis direction orthogonal to the Y-axis direction that is the arrangement direction of the plurality of LEDs. A first pattern P1 including the first reference pattern 100 and the second pattern P2 including the second lightness information acquisition pattern 250, which are located inside the first pattern 150 and the first lightness information acquisition pattern 150, A pattern forming step that is formed side by side in the axial direction, a plurality of LEDs corresponding to the first reference pattern 100, and a plurality of LEDs corresponding to the first lightness information acquisition pattern 150 of the plurality of LEDs on the basis of the first reference pattern 100. A first associating step of associating the LED with a plurality of pixel columns of the first lightness information acquisition pattern 150, and the first lightness information acquisition pattern 15 The first brightness information in the plurality of pixel columns is acquired, and the second brightness information in the plurality of pixel columns corresponding to the plurality of pixel columns of the first reference pattern 100 of the second brightness information acquisition pattern 250 is acquired. Based on the lightness information acquisition step and the first lightness information, the light emission amounts of the plurality of LEDs corresponding to the first lightness information acquisition pattern 150 are adjusted, and the lightness information acquisition step corresponds to the first reference pattern 100 based on the second lightness information. A light emission amount adjustment step for adjusting the light emission amounts of the plurality of LEDs.

  In this case, the first pixel pattern of the first reference pattern 100 located near the plurality of pixel columns of the first brightness information acquisition pattern 150 and the plurality of LEDs corresponding to the first reference pattern 100 are used as a reference. The plurality of pixel columns of the brightness information acquisition pattern 150 can be associated with the plurality of LEDs corresponding to the first brightness information acquisition pattern 150 with high accuracy. In addition, a plurality of pixel columns corresponding to a plurality of pixel columns of the first reference pattern 100 in the second brightness information acquisition pattern 250 can be associated with a plurality of LEDs corresponding to the first reference pattern 100.

  Then, based on the first brightness information in the plurality of pixel rows of the first brightness information acquisition pattern 150, the light emission amounts of the plurality of LEDs corresponding to the plurality of pixel rows of the first brightness information acquisition pattern 150 are adjusted, A plurality of second brightness information acquisition patterns 250 corresponding to the plurality of pixel columns of the first reference pattern 100 based on the second brightness information in the plurality of pixel columns corresponding to the plurality of pixel columns of the first reference pattern 100. The amount of light emitted from the LED is adjusted.

  As a result, the amount of light emitted from each LED of the print head 2200 can be adjusted with high accuracy, and as a result, the occurrence of uneven density (vertical stripes) in the image (output image) formed using the print head is suppressed. . That is, the quality of the output image can be improved.

  On the other hand, if the reference pattern is arranged outside the lightness information acquisition pattern, a plurality of pixel rows of the reference pattern located far from the plurality of pixel rows of the lightness information acquisition pattern, and a plurality corresponding to the reference pattern With this LED as a reference, a plurality of pixel columns of the lightness information acquisition pattern and a plurality of LEDs corresponding to the lightness information acquisition pattern are associated with each other. The quality of the output image cannot be improved.

  Further, according to the light amount adjustment method of the print head of the present embodiment, the second pattern P2 is different from the first reference pattern 100 in the second reference pattern 200 having a position in the Y-axis direction. In addition, prior to the second light emission quantity adjustment step, the first brightness information acquisition pattern 250 of the second brightness information acquisition pattern 250 is based on the plurality of LEDs corresponding to the second reference pattern 200 and the plurality of pixel rows of the second reference pattern. It further includes a second association step of associating a plurality of pixel columns corresponding to the plurality of pixel columns of the reference pattern with a plurality of LEDs corresponding to the first reference pattern among the plurality of LEDs.

  In this case, the second lightness information acquisition pattern 250 of the second lightness information acquisition pattern 250 is based on the second reference pattern 200 located near the first reference pattern and the plurality of LEDs corresponding to the plurality of pixel columns of the second reference pattern 200. The plurality of pixel columns corresponding to the plurality of pixel columns of the first reference pattern 100 and the plurality of LEDs corresponding to the first reference pattern 100 can be accurately associated.

  Even if the conveyance direction of the recording paper W deviates from the X-axis direction, the positional relationship between the first reference pattern 100 and the first brightness information acquisition pattern 150 in the Y-axis direction, and the second reference pattern 200 and the second brightness. Since the positional relationship in the Y-axis direction of the information acquisition pattern 250 is unchanged, the correspondence between the plurality of pixel columns of the first lightness information acquisition pattern 150 and the plurality of LEDs corresponding to the first lightness information acquisition pattern 150 And the correspondence between the plurality of pixel columns corresponding to the plurality of pixel columns corresponding to the first reference pattern 100 and the plurality of LEDs corresponding to the first reference pattern in the second lightness information acquisition pattern 250. Can be done.

  Further, the length (for example, for 4 pixels) of one side of the plurality of square patterns constituting the lightness information acquisition pattern is set to be larger than the reading interval of the scanner (for example, for 2 pixels). In this case, a plurality of square patterns can be read with high definition (high SN ratio).

  The first reference pattern 100 is formed near the center of the recording paper W in the Y-axis direction. That is, the first reference pattern 100 is located at the approximate center of the pattern P in the Y-axis direction.

  In this case, among a plurality of pixel columns of the first lightness information acquisition pattern 150, a plurality of pixel columns located on the −Y side of the first reference pattern 100 and a plurality of pixel columns corresponding to the first lightness information acquisition pattern 150. Among the plurality of LEDs corresponding to the first reference pattern 100 among the plurality of LEDs located on the −Y side, and among the plurality of pixel columns of the first lightness information acquisition pattern 150, the first reference Among the plurality of pixels corresponding to the first reference pattern 100 among the plurality of pixels corresponding to the first lightness information acquisition pattern 150 and the plurality of pixels arranged on the + Y side of the pattern 100, the plurality of pixels positioned on the + Y side The association with the LED can be performed as evenly as possible, and as a result, the occurrence of uneven density in the output image can be suppressed as much as possible.

  Further, the second reference pattern 200 is formed close to the first reference pattern 100 in the Y-axis direction.

  In this case, the plurality of LEDs corresponding to the first reference pattern 100, the plurality of pixel columns corresponding to the plurality of pixel columns of the first reference pattern 100, and the first reference pattern 100 Correlation with a plurality of LEDs corresponding to the can be performed with higher accuracy.

  In this embodiment, the average value of the brightness information of a plurality of pixels in each pixel column of the brightness information acquisition pattern read by the scanner 1085 is obtained, and the average value is acquired as the brightness information of the pixel column. Based on the information, the light emission quantity of the corresponding LED is adjusted. As a result, even if the brightness information of a plurality of pixels in each pixel column has a variation due to, for example, a measurement error due to the reading accuracy of the scanner 1085, the influence due to the variation can be reduced, and the generation of vertical stripes can be effectively performed. Can be suppressed.

  Further, since the reference pattern is an elongated line pattern extending in the X-axis direction, the Y position of the reference pattern can be detected with high accuracy.

  Therefore, in the laser printer 1000, the light amount of each print head 2200 is adjusted by the light amount adjustment method of the present embodiment, so that it is possible to obtain a high-quality output image in which the occurrence of density unevenness is sufficiently suppressed.

  Further, the laser printer 1000 can be manufactured by using the light amount adjustment method of the present embodiment. That is, when the laser printer 1000 is manufactured, the light amount of the print head 2200 can be adjusted by performing the above steps S1 to S15 for the print head 2200. As a result, the laser printer 1000 with excellent image quality can be provided.

In the above embodiment, the plurality of square patterns constituting the lightness information acquisition pattern include 16 pixels arranged in a matrix of 4 rows and 4 columns. , And n ² pixels arranged in a matrix of n rows and n columns (n is a natural number). In the above embodiment, the reference pattern includes 96 pixels arranged in a matrix of 24 rows and 4 columns. However, the present invention is not limited to this, and in short, k rows and i columns (k and i are natural numbers). And k> i pixels are preferably arranged in a matrix of k> i).

  Further, it is more preferable that i = n. In this case, the number of pixel columns corresponding to the first reference pattern and the number of LEDs corresponding to the first reference pattern in the second brightness information acquisition pattern are the same, and can be associated individually.

  As an example, FIGS. 10A and 10B show a case where n = 3, k = 24, i = 3, and m = 8. As an example, FIGS. 11A and 11B show a case where n = 2, k = 24, i = 2, and m = 12. The reference patterns shown in FIGS. 10A and 11A are formed by constantly turning off the three LEDs corresponding to the reference patterns. In addition, the reference patterns shown in FIGS. 10B and 11B are formed by constantly lighting three LEDs corresponding to the reference pattern, and the brightness of the pixel row of the reference pattern is a change in brightness. Represented as a valley.

  Note that the minimum unit (square pattern) of frequently used images varies depending on the printer (model). Of the minimum units of n rows and n columns, it is effective to correct the density unevenness of the output image using a pattern composed of the minimum units that are frequently used according to the printer.

  In the above embodiment, the brightness information acquisition pattern is a halftone pattern with an image area ratio of 50%, but is not limited thereto. For example, in FIGS. 12A and 12B, the brightness information acquisition pattern is a halftone pattern with an image area ratio of 25%. Also in this case, the square pattern (minimum unit) is arranged in a staggered pattern so as to be formed by lighting each LED of the print head 2200 at least once. Note that the reference pattern shown in FIG. 12A is formed by constantly turning off three LEDs corresponding to the reference pattern. In addition, the reference pattern shown in FIG. 12B is formed by constantly lighting three LEDs corresponding to the reference pattern. In this case as well, it is effective to correct the density unevenness of the output image by using a pattern constituted by the minimum unit of the frequently used image.

  Moreover, in the said embodiment, although the 1st and 2nd pattern has a reference pattern 1 each, at least one of the 1st and 2nd pattern is a Y-axis direction of the area | region where an X-axis direction differs. A plurality of reference patterns may be provided at a plurality of different positions.

  Also in this case, a plurality of pixel columns of one lightness information acquisition pattern and a plurality of pixel information corresponding to the lightness information acquisition pattern with reference to a pixel column of one reference pattern and an LED corresponding to the one reference pattern Pixels corresponding to one reference pattern pixel column of another lightness information acquisition pattern with reference to the pixel column of another reference pattern and the LED corresponding to the other reference pattern, associating with the LED The correspondence between the column and the LED corresponding to one reference pattern may be performed.

  As a specific example, in FIG. 13A, the first pattern has one reference pattern on the −Y side, and the second pattern has two reference patterns on the −X side region Y. A pattern P ′ included in the central portion in the axial direction and the + Y side portion of the + X side region is shown. In FIG. 13B, the first pattern has one reference pattern on the −Y side, and the second pattern has three reference patterns on the −Y side of the −X side region. A pattern P ″ that is provided in the middle in the Y-axis direction in the central region in the X-axis direction and in the + Y-side portion in the + X-side region is shown.

  In FIG. 13A, for example, the −Y side portion of the first pattern (the portion closest to the −X side reference pattern), the central portion in the Y axis direction of the region on the −X side of the second pattern (X In each of the three portions, the portion near the center reference pattern in the axial direction) and the + Y side portion (the portion closest to the reference pattern on the + X side) of the + X side region of the second pattern, By associating the pixel columns with the LEDs corresponding to the brightness information acquisition pattern, the accuracy of the association can be further improved. Then, in each of the above three parts, if the brightness information is acquired and correction data for the light emission amount of the corresponding LED is created based on the lightness information, the light emission amount of each LED can be adjusted with higher accuracy. .

  In FIG. 13B, the light emission quantity of each LED can be adjusted with higher accuracy than in the case shown in FIG.

  In other words, the closer the distance between the reference pattern and each pixel column in the brightness information acquisition region where the Y position is determined based on the reference pattern, the more accurate the association between the LED and the pixel column can be improved.

  In the above embodiment, the light amount adjustment of the print head 2200 (steps S1 to S15 in FIG. 5) is performed once, but the same light amount adjustment (steps S1 to S15 in FIG. 5) may be performed a plurality of times.

  That is, a pattern P is formed on the recording paper using the print head 2200 whose light amount has been adjusted by the light amount adjustment method of the above embodiment, and the pattern P is read by the scanner 1085. Similarly, the light emission of each LED of the print head 2200 The amount of light may be corrected. In this way, by performing re-correction, it is possible to reduce density unevenness that could not be eliminated by the previous correction, so that the quality of the output image can be further improved.

  In the above embodiment, the resolution of the print head 2200 is set equal to the reading resolution of the scanner 1085, but the present invention is not limited to this. For example, the print head resolution may be an integral multiple of the scanner read resolution, that is, the minimum read unit of the scanner may be an integral multiple of the minimum print head unit, and the correction data may be generated at the read resolution (in the minimum read unit). .

  For example, the minimum reading unit of the scanner is 42 μm (600 dpi), which is twice the minimum unit of the print head 21 μm (equivalent to 1200 dpi), the correction data is obtained in units of 42 μm, and the correction data is obtained from two adjacent LEDs of the print head. It is good also as expressing with the average value of the adjustment value of the emitted light quantity of (odd element and even element). In this case, there is an effect that the correction gradation can be increased. For example, even if the minimum unit of the correction data is 1%, gradations in increments of 0.5% can be realized by setting the adjustment values of the light emission amounts of the odd and even elements as shown in Table 2 below. As a result, subtle density unevenness can be corrected.

  For example, if the minimum reading unit of the scanner is three times the minimum unit of the print head, gradation can be expressed in 0.33% increments.

  In the above-described embodiment, the Y position of the first lightness information acquisition pattern 150 and the Y position of the first lightness information acquisition using the Y position of the first reference pattern 100 and the LED corresponding to the first reference pattern 100 as a reference. The LED corresponding to the pattern 150 is associated with the Y position of the second reference pattern 200 and the first reference of the second lightness information acquisition pattern 250 based on the LED corresponding to the second reference pattern 200. Although the Y position corresponding to the Y position of the pattern 100 is associated with the LED corresponding to the first reference pattern 100, the reverse may be possible.

  That is, based on the Y position of the second reference pattern 200 and the LED corresponding to the second reference pattern 200, the Y position of the second lightness information acquisition pattern 250 and the LED corresponding to the second lightness information acquisition pattern With the Y position of the first reference pattern 100 and the Y position of the second reference pattern 200 of the first brightness information acquisition pattern 150 using the LED corresponding to the first reference pattern 100 as a reference. Correspondence between the corresponding Y position and the LED corresponding to the second reference pattern 200 may be performed.

  In the above embodiment, the first and second reference patterns 100 and 200 are located near the center of the pattern P in the Y-axis direction, but are not limited thereto. For example, at least one of the first and second reference patterns 100 and 200 may be located near the + Y side end of the pattern P or near the −Y side end.

  In the above embodiment, each of the first and second patterns includes a reference pattern and a brightness information acquisition pattern including two checker patterns sandwiching the reference pattern in the Y-axis direction. Not limited to. For example, it may be composed of a reference pattern and one checker pattern surrounding the reference pattern. Further, for example, the reference pattern and one or two halftone (halftone) solid patterns sandwiching the reference pattern may be used. Further, for example, it may be configured by a reference pattern and one halftone (halftone) solid pattern surrounding the reference pattern.

  In the above embodiment, both the first and second patterns P1 and P2 have the reference pattern, but only one of the first and second patterns may have the reference pattern. good. For example, the first pattern P1 may include the first reference pattern 100, and the second pattern may include only the brightness information acquisition pattern. In this case, the brightness information of the pixel column at the same Y position as the Y position of each pixel column of the first reference pattern 100 of the brightness information acquisition pattern of the second pattern is acquired, and the first information is obtained based on the brightness information. The light emission amount of each LED corresponding to the reference pattern 100 may be adjusted. In this case, only the brightness information of a plurality of pixel columns corresponding to the plurality of pixel columns of the first reference pattern 100 in the brightness information acquisition pattern of the second pattern may be acquired.

  Specifically, as illustrated in FIG. 14, as an example, the second pattern P2 ′ of the pattern P ″ ′ is configured only by the checker pattern CP (lightness information acquisition pattern), and the second pattern P2 ′. The Y positions of the four pixel columns corresponding to the four pixel columns of the first reference pattern 100 are obtained with reference to one end or the other end of the second pattern P2 ′ in the Y-axis direction, and brightness information at the Y position is obtained. You may make it acquire. In this case, although the accuracy of association between the LED and the pixel column is inferior to that in the above embodiment, the width of the region corresponding to the first reference pattern 100 in the second pattern P2 ′ in the Y-axis direction is narrow. Does not significantly affect the quality of the output image.

  In the above embodiment, each of the first and second patterns has one reference pattern, but at least one of the first and second patterns has a plurality of reference patterns arranged in the Y-axis direction. May be. In this case, one pattern having a plurality of reference patterns is divided into a plurality of regions including the respective reference patterns, and the LEDs corresponding to the regions are divided in each divided region with reference to the reference pattern in the region. And the Y position of the area may be associated with each other. In this case, it is necessary to associate the LED corresponding to each of the plurality of reference patterns of one pattern with the Y position corresponding to the Y position of the reference pattern of another pattern. As a result, the LED can be associated with the Y position of one pattern with higher accuracy.

  In this case, as the number of reference patterns arranged in the Y-axis direction increases, the distance between each reference pattern and each pixel column in the brightness information acquisition region where the Y position is obtained with reference to the reference pattern becomes shorter. And the accuracy of the association between the pixel columns can be improved.

  In the above-described embodiment, the resolution of the print head 2200 and the resolution of the scanner 1085 are 1200 dpi, but the present invention is not limited to this, and other values may be used.

  In the above-described embodiment, the reference pattern is a line pattern composed of a plurality of pixels arranged in the X-axis direction each with a resolution of 1200 dpi and composed of four pixel columns adjacent in the Y-axis direction. However, the present invention is not limited to this, and other patterns can be used. That is, the reference pattern may be another pattern as long as the position in the Y-axis direction can be detected with high accuracy.

  The width of the reference pattern formed on the recording paper W (dimension in the Y-axis direction) can be changed as appropriate. However, if the width of the reference pattern is too thick, an error may increase in association between the plurality of pixel columns of the reference pattern and the plurality of LEDs corresponding to the reference pattern. It is preferable that the width is 2 dpi or less of 600 dpi. Further, since the reference pattern may be too thin, an error may increase, so that it is preferable that the reference pattern has a dot width of 1200 dpi or more.

  Moreover, in the said embodiment, although the 1st and 2nd pattern is integrally formed in series, you may form discontinuously (separately). That is, the first and second patterns may be formed apart from each other in the X-axis direction.

  Further, the shape, size, number, arrangement, and tone (gradation) of the plurality of patterns constituting the reference pattern and the brightness information acquisition pattern are not limited to those described in the above embodiment, and can be changed as appropriate. . For example, the reference pattern may be obtained by adding another pattern to the line pattern. For example, the reference pattern may be a halftone pattern. Further, the plurality of patterns constituting the lightness information acquisition pattern are not limited to the square pattern, but may be a rectangular pattern whose longitudinal direction is the X-axis direction, for example. Further, the plurality of patterns constituting the brightness information acquisition pattern may not be arranged in a staggered pattern. However, even in this case, it is desirable that the image area ratio of each pixel column constituting the brightness information acquisition pattern, that is, the ratio of the black image in the entire pixel column is the same.

  In short, in the first pattern, a plurality of LEDs corresponding to the first lightness information acquisition pattern are turned on at least once, and a plurality of LEDs corresponding to the first reference pattern are always turned on or off. The second pattern is formed by turning on the LED corresponding to the first reference pattern at least once and turning on or off the LED corresponding to the second reference pattern at all times. It is desirable.

  In the above embodiment, the plurality of LEDs are arranged in a line in the Y-axis direction. However, the present invention is not limited to this. For example, the LEDs may be two-dimensionally arranged so that the positions in the Y-axis direction are different from each other. In short, the plurality of LEDs may be arranged so that the positions in the Y-axis direction are different from each other.

  In the above embodiment, the laser printer 1000 is not equipped with a scanner for reading an original. However, when a printer equipped with the scanner is used, the pattern P may be read by the scanner.

  In the above-described embodiment, the light amount of the print head 2200 is adjusted at the time of manufacturing the laser printer 1000. However, instead of or in addition, for example, when the laser printer 1000 is maintained, printing is performed with the same light amount adjustment method. The light amount of the head 2200 may be adjusted.

  In the above-described embodiment, the control device 3022 may not include the light amount adjustment circuit 3223. In this case, for example, the CPU 3210 may perform the processing performed by the light amount adjustment circuit 3223 in the above embodiment.

  In the above embodiment, the printer control device 1060 may perform at least a part of the processing in the control device 3022. Further, the control device 3022 may perform at least a part of the processing in the printer control device 1060.

  Moreover, in the said embodiment, although the LED corresponding to a reference | standard pattern is four, 1 to 3 or 5 or more may be sufficient.

  Moreover, in the said embodiment, although LED is used as a light emission part, it is not restricted to this, For example, you may use organic EL, a laser, etc.

  In the above-described embodiment, the monochrome laser printer 1000 including one print head is employed. However, even when a color printer including a plurality of print heads individually corresponding to a plurality of colors is employed, the color printer During the manufacture or maintenance, the density unevenness of the output image (color image) can be eliminated by adjusting the light amount of the print head using the same light amount adjustment method for each color. As a result, a color printer that can improve the quality of the output image can be provided.

  In the above embodiment, the Y positions of the 20 LEDs corresponding to the first lightness information acquisition pattern 150 are obtained using the average value of the Y positions of the four LEDs corresponding to the first reference pattern as a reference. However, it is not limited to this. For example, when there is one LED corresponding to the first reference pattern, the Y position of the LED is used as a reference, and when the LED corresponding to the first reference pattern is an odd number of 3 or more, the Y position of the center LED is set. You may ask for it as a standard.

  In the above-described embodiment, the laser printer 1000 is used as the image forming apparatus. However, instead of this, for example, a copying machine or a multifunction machine including a copying machine and other devices may be used. For example, when a scanner for reading an original is incorporated in a copying machine or the like, the scanner may be used for reading the pattern P.

  In the flowchart of FIG. 5 in the above embodiment, the order of step S5 and step S7 may be reversed, the order of step S9 and step S11 may be reversed, and the order of step S13 and step S15 may be reversed.

  Below, other embodiment of this invention is described based on FIGS. 15-27. FIG. 15 shows a schematic configuration of a color printer 2000 according to another embodiment.

  As shown in FIG. 15, the color printer 2000 is a tandem multicolor printer that forms a full-color image by superimposing four colors (black, yellow, magenta, and cyan). Light source device 2010 having print heads (2200a, 2200b, 2200c, 2200d), four photosensitive drums (2030a, 2030b, 2030c, 2030d), four cleaning units (2031a, 2031b, 2031c, 2031d), and four charging devices (2032a, 2032b, 2032c, 2032d), four developing rollers (2033a, 2033b, 2033c, 2033d), four toner cartridges (2034a, 2034b, 2034c, 2034d), and four first transfer rollers ( 041a, 2041b, 2041c, 2041d), transfer belt 2040, second transfer roller 2042, fixing device 2050, paper feed roller 2054, registration roller pair 2056, paper discharge roller 2058, paper feed tray 2060, paper discharge tray 2070, communication control. An apparatus 2080, a scanner 2085, and a printer control apparatus 2090 that controls the above-described units are provided.

  Here, in the XYZ three-dimensional orthogonal coordinate system, a direction parallel to the longitudinal direction (rotation axis direction) of each photosensitive drum is defined as a Y-axis direction, and a direction parallel to the arrangement direction of four photosensitive drums is defined as an X-axis direction. .

  The communication control device 2080 controls bidirectional communication with a host device (for example, a personal computer) via a network or the like.

  The printer control device 2090 includes a CPU, a ROM described in a program written in code readable by the CPU, various data used when executing the program, a RAM as a working memory, an analog data An AD conversion circuit for converting the signal into digital data. Then, the printer control device 2090 sends image information from the host device to the light source device 2010.

  The photosensitive drum 2030a, the print head 2200a, the charging device 2032a, the developing roller 2033a, the toner cartridge 2034a, the cleaning unit 2031a, and the first transfer roller 2041a are used as a set, and form an image forming station (hereinafter referred to as a black image). (Also referred to as “K station” for convenience).

  The photosensitive drum 2030b, the print head 2200b, the charging device 2032b, the developing roller 2033b, the toner cartridge 2034b, the cleaning unit 2031b, and the first transfer roller 2041b are used as a set, and an image forming station (hereinafter, for convenience, forms a yellow image). (Also referred to as “Y station”).

  The photosensitive drum 2030c, the print head 2200c, the charging device 2032c, the developing roller 2033c, the toner cartridge 2034c, the cleaning unit 2031c, and the first transfer roller 2041c are used as a set, and form an image forming station (hereinafter, magenta image). For convenience, it is also referred to as “M station”).

  The photosensitive drum 2030d, the print head 2200d, the charging device 2032d, the developing roller 2033d, the toner cartridge 2034d, the cleaning unit 2031d, and the first transfer roller 2041d are used as a set, and form an image forming station (hereinafter referred to as a cyan image). (Also referred to as “C station” for convenience).

  Each photosensitive drum has a photosensitive layer formed on the surface thereof. Each photosensitive drum is rotated in the direction of the arrow in the plane of FIG. 15 by a rotation mechanism (not shown). Hereinafter, the four photosensitive drums 2030a to 2030d are also referred to as photosensitive drums 2030 when it is not necessary to distinguish them. The photoreceptor drum is an example of an image carrier.

  Each charging device uniformly charges the surface of the corresponding photosensitive drum.

  The light source device 2010 is charged with light modulated for each color based on multicolor image information (black image information, yellow image information, magenta image information, cyan image information) from the printer control device 2090. Irradiate the surface of the photosensitive drum. Thereby, a latent image corresponding to the image information is formed on the surface of each photosensitive drum. The latent image formed here moves in the direction of the corresponding developing roller as the photosensitive drum rotates. Details of the light source device 2010 will be described later.

  As each developing roller rotates, the toner from the corresponding toner cartridge is thinly and uniformly applied to the surface thereof. Then, when the toner on the surface of each developing roller comes into contact with the surface of the corresponding photosensitive drum, the toner moves only to a portion irradiated with light on the surface and adheres to the surface. In other words, each developing roller causes toner to adhere to the latent image formed on the surface of the corresponding photosensitive drum so as to be visualized. Here, the toner-attached image (toner image) moves in the direction of the transfer belt 2040 as the photosensitive drum rotates.

  Each toner image of black, yellow, magenta, and cyan is sequentially transferred at a predetermined timing onto a transfer belt 2040 to which a bias voltage is applied via a corresponding first transfer roller, and is superposed to form a multicolor image. It is formed.

  Recording paper is stored in the paper feed tray 2060. A paper feed roller 2054 is disposed in the vicinity of the paper feed tray 2060, and the paper feed roller 2054 takes out the recording paper one by one from the paper feed tray 2060 and conveys it to the registration roller pair 2056. The registration roller pair 2056 feeds the recording paper at a predetermined timing toward the gap between the transfer belt 2040 and the transfer roller 2042 to which a bias voltage is applied. As a result, the color image on the transfer belt 2040 is transferred to the recording paper. Here, the recording paper on which the color image is transferred is sent to the fixing device 2050.

  In the fixing device 2050, heat and pressure are applied to the recording paper, thereby fixing the toner on the recording paper. Here, the recording paper on which the toner is fixed is sent to a paper discharge tray 2070 via a paper discharge roller 2058 and is sequentially stacked on the paper discharge tray 2070.

  Each cleaning unit removes toner (residual toner) remaining on the surface of the corresponding photosensitive drum. The surface of the photosensitive drum from which the residual toner has been removed returns to the position facing the corresponding charging device again.

  As an example, the scanner 2085 is disposed in the vicinity of the recording paper conveyance path between the fixing device 2050 and the paper discharge tray 2070. The scanner 2085 irradiates a predetermined image formed on a recording sheet, which will be described later, with light irradiation means including a light emitting element, and receives the reflected light with a plurality of light receiving elements, thereby reading the predetermined image. The scanner 2085 scans the entire width direction (Y-axis direction) of the recording paper in the Y-axis direction with light. The reading resolution of the scanner 2085 is set to 600 dpi as an example.

  Next, the configuration of the light source device 2010 will be described.

  The light source device 2010 includes a control device 3022A in addition to the four print heads (2200a, 2200b, 2200c, 2200d). These are attached to an optical housing (not shown).

  For example, the four print heads 2200a to 2200d are arranged on the −Z side of the corresponding photosensitive drum. That is, the four print heads 2200a to 2200d are arranged in the X-axis direction as an example. In the following, the four print heads 2200a to 2200d are collectively referred to as print heads PH when not distinguished from each other.

  As shown in FIG. 16, the print head PH includes, for example, an organic EL device 10 and an imaging optical element 12. Here, EL is an abbreviation for “electroluminescence”.

  The organic EL device 10 is accommodated in a housing (not shown) as an example. Accordingly, the housing has conductivity (for example, conductivity) that shields the disturbance noise from external electrical disturbance noise (for example, high voltage noise from the corresponding charging device). By adopting a material made of a material, a surface treated with electrical conductivity, or the like, noise resistance can be improved.

  As shown in FIG. 17, the organic EL device 10 includes, as an example, a plurality of ELA chips 16 (organic EL array chips), a plurality of driving ICs 18, a cable connecting connector 20, and a first substrate 22 on which these are mounted. Etc.

  As the first substrate 22, for example, an elongated printed circuit board mainly composed of glass epoxy is used.

  As an example, the plurality of ELA chips 16 are arranged on the first substrate 22 in the Y-axis direction. Each ELA chip 16 includes, as an example, a second substrate 16a and a plurality of organic EL elements 16b arranged in the Y-axis direction on the second substrate 16a. That is, the plurality of organic EL elements 16b are arranged in the Y-axis direction. Each organic EL element 16b corresponds to one pixel. The organic EL element has low power consumption.

  Specifically, on the first substrate 22, corresponding to the image writing width L in the Y-axis direction (the width of the effective writing area, see FIG. 19), that is, so as to cover the entire effective writing area. A plurality of (for example, about several tens to several hundreds) second substrates 16a are arranged in the Y-axis direction. On each second substrate 16a, a plurality of (for example, several tens to several hundreds) organic EL elements 16b are arranged at predetermined intervals Pi (hereinafter also referred to as adjacent element intervals Pi) in the Y-axis direction ( (See the partially enlarged view of FIG. 17).

  More specifically, the plurality of second substrates 16a are defined as the distance between two organic EL elements 16b positioned at two adjacent ends of the two adjacent second substrates 16a, that is, between the two adjacent second substrates 16a. Of these, the distance between the organic EL element 16b located on the most one side and the organic EL element 16b located on the other most side (hereinafter referred to as the adjacent chip element interval Pt) is equal to the adjacent element interval Pi. It is mounted on the first substrate 22 so as to be. That is, all the organic EL elements 16b are arranged in the Y-axis direction at equal intervals (Pi). The width of each ELA chip 16 in the Y-axis direction of the second substrate 16a is a fixed width that is set in production so that the number of wafers taken from the wafer is maximized.

  That is, the plurality of organic EL elements 16b are mounted on the first substrate 22 via the second substrate 16a at intervals at which images are formed at a desired pixel density (resolution).

  Specifically, for example, when the resolution is 600 dpi, both the adjacent element interval Pi and the adjacent chip element interval Pt need to be set to 42.3 μm. Similarly, when the resolution is set to 1200 dpi, for example, the intervals Pi and Pt must be set to 21.2 μm.

  More specifically, in order to write an A4 width (210 mm) at a resolution of 1200 dpi, it is necessary to arrange 9906 organic EL elements 16b at intervals of 21.2 μm (= Pi = Pt) in the Y-axis direction. For example, ten ELA chips 16 having 1000 organic EL elements 16b need to be mounted. Similarly, in order to write in an A3 width (297 mm) at a resolution of 1200 dpi, it is necessary to arrange 14010 organic EL elements 16b in the Y-axis direction. For example, 15 ELA chips 16 having 1000 organic EL elements 16b Must be implemented individually.

  Here, D in FIG. 17 is set such that the total exposure width D of the print head 2200 is obtained by adding the margin (registration adjustment width, mounting error) in the Y-axis direction to the image writing width L (see FIG. 19). Has been.

  Specifically, when an A3 size image is formed, it is preferable that the image writing width L = 297 mm and the total exposure width D = 302 mm or more (image writing width L + 5 mm or more). Here, “more than” means that the width in the Y-axis direction of the second substrate 16a of the ELA chip 16 is a fixed width as described above, and thus is an integral multiple of the fixed width.

  As described above, the first substrate 22 on which the plurality of ELA chips 16 are mounted is arranged with respect to the housing such that the emission direction of each organic EL element 16b is substantially the −X direction and the longitudinal direction is the Y axis direction. Is positioned.

  As an example, the plurality of drive ICs 18 are mounted side by side in the Y-axis direction on the −Z side of the plurality of ELA chips 16 on the −X side surface of the first substrate 22. Each drive IC 18 has a plurality of drive transistors (not shown) that individually drive the plurality of organic EL elements 16b.

  The cable connector 20 is a connector to which a transmission cable (not shown) for connecting the control device 3022A and the organic EL device 10 is connected. As an example, a plurality of ELA chips 16 on the first substrate 22 are mounted. It is mounted on the surface (the surface on the + X side) opposite to the surface (the surface on the −X side).

  The organic EL device 10 configured as described above can emit light (diffused light) from each organic EL element 16b in the −X direction (see FIG. 16).

  For example, as shown in FIG. 16, the imaging optical element 12 is attached to the housing so as to be positioned on the optical path of light from the organic EL device 10 (here, the −X side of the organic EL device 10). It has been.

  More specifically, the imaging optical element 12 includes a prism array 12a extending in the Y-axis direction, an incident side lens array 12b continuous with the incident surface (+ X side surface) of the prism array 12a, and an exit surface of the prism array 12a. And an exit-side lens array 12c that is continuous with the (+ Z-side surface).

  The prism array 12a has a plurality of microprisms arranged in the Y-axis direction individually corresponding to the plurality of organic EL elements 16b. Each of the entrance-side lens array 12b and the exit-side lens array 12c has a plurality of lenses arranged in the Y-axis direction corresponding to the plurality of organic EL elements 16b individually.

  Therefore, the light (diffused light) emitted from the organic EL device 10 in the −X direction is incident on the prism array 12a via the incident side lens array 12b, and the optical path is bent by 90 ° by the prism array 12a. The light is emitted while being converged to the + Z side via the lens array 12c.

  Light (converged light) emitted from the exit-side lens array 12c, that is, light emitted from the print head PH forms an image on the surface of the corresponding photosensitive drum, and a light spot having a desired diameter is formed on the surface. The

  The control device 3022A has the same configuration as the control device 3022 shown in FIG. 4 except that it controls four print heads PH. That is, the control device 3022A includes a CPU 3210, a flash memory 3211, a RAM 3212, an IF (interface) 3214, a pixel clock generation circuit 3215, an image processing circuit 3216, a write control circuit 3219, a light amount adjustment circuit 3223, a light source drive circuit 3221, and the like. doing.

  The pixel clock generation circuit 3215 generates a pixel clock signal. The pixel clock signal can be phase-modulated with a resolution of 1/8 clock.

  The image processing circuit 3216 performs predetermined halftone processing on the image data rasterized for each color by the CPU 3210 and then creates dot data for each organic EL element of each print head PH.

  The write control circuit 3219 starts writing at a predetermined timing for each station. Then, the dot data of each organic EL element 16b is superimposed on the pixel clock signal from the pixel clock generation circuit 3215 in accordance with the write start timing, and independent modulation data is generated for each organic EL element. Further, the write control circuit 3219 performs APC (Auto Power Control) at every predetermined timing.

  As will be described later in detail, the light amount adjustment circuit 3223 creates and stores light amount correction data of the organic EL device 10 of each print head PH, and sends the light amount correction data to the light source drive circuit 3221 as appropriate.

  The light source drive circuit 3221 corrects the drive signal corresponding to each modulation data from the write control circuit 3219 using the light amount correction data from the light amount adjustment circuit 3223, and outputs the corrected drive signal to each print head PH. To do.

  An IF (interface) 3214 is a communication interface that controls bidirectional communication with the printer control apparatus 2090.

  The flash memory 3211 stores various programs described in codes readable by the CPU 3210 and various data necessary for executing the programs.

  The RAM 3212 is a working memory.

  The CPU 3210 operates according to a program stored in the flash memory 3211 and controls the entire light source device 2010.

  Here, for example, individual differences (light emission amount, beam profile, wavelength, orientation distribution) of a plurality of organic EL elements, and optical characteristics (imaging characteristics, transmittance) of a plurality of lenses and a plurality of microprisms of the imaging optical element 12. If the amount of light emitted from the print head PH varies due to variations in density, etc., density unevenness (vertical stripes) occurs in the image (output image) formed on the recording paper W.

  Therefore, the light amount of the print head PH is adjusted to suppress the occurrence of density unevenness in the output image.

  Hereinafter, an example of the light amount adjustment method of the print head PH will be described with reference to the flowchart of FIG. For example, the light amount adjustment is performed by an operator when the color printer 2000 is manufactured. Since the light amount adjustment of the print head PH is performed for each station, here, as a representative, one station (for one print head PH) will be described in detail. Hereinafter, the organic EL element 16b is also referred to as a “light emitting unit”.

  In the first step S21, first light amount correction data for correcting light emission amounts of a plurality of light emitting units is created and stored.

  Specifically, first, all the light emitting portions of the print head PH are turned on, and the light emitted from each light emitting portion and passing through the imaging optical element 12, that is, the amount of each light from the print head PH is measured with a power meter. To do. At this time, the drive current supplied to all the light emitting units is made the same. Then, first light amount correction data, which is data for correcting the light emission amount of each light emitting unit so as to equalize the light amount of each light from the print head PH, is created and stored in the flash memory 3211. That is, the first light amount correction data is data including light amount correction data of each light emitting unit.

  In the next step S23, all the light emitting portions of the print head PH are turned on using the first light quantity correction data, and a pattern Q (reference image) is formed on the recording paper W via the corresponding photosensitive drum 2030 or the like.

  Here, as an example, the pattern Q includes, as shown in FIG. 19, a first pattern Q1, a second pattern Q2 positioned on the + Z side of the first pattern Q1, and the first pattern Q1. And a third pattern Q3 located on the −Z side. Here, the first to third patterns Q1 to Q3 are integrated into a series.

  The first pattern Q1 includes a first brightness information acquisition pattern α1, a first reference pattern β1 located in the center of the first brightness information acquisition pattern α1 in the Y-axis direction, and a first brightness information acquisition pattern α1. And an end reference pattern γ1a adjacent to the −Y side end, and an end reference pattern γ1b adjacent to the + Y side end of the first brightness information acquisition pattern α1. Note that the first lightness information acquisition pattern α1 includes two regions sandwiching the first reference pattern β1 in the Y-axis direction. Hereinafter, when the two end reference patterns γ1a and γ1b are not distinguished, they are collectively referred to as an end reference pattern γ1.

  The first lightness information acquisition pattern α1 has a plurality of unit light emission patterns arranged in a zigzag pattern along the YZ plane, as can be seen from FIG. Yes. Each unit light emission pattern has four portions arranged in a matrix of 2 rows and 2 columns with the Z-axis direction as the row direction and the Y-axis direction as the column direction. Of these four parts, one part located on the + Z side and the −Y side has four halftones arranged in a matrix of 2 rows and 2 columns, with the Z axis direction as the row direction and the Y axis direction as the column direction. Consists of pixels. Of these four parts, each of the other three parts is composed of four white pixels arranged in a matrix of 2 rows and 2 columns with the Z-axis direction as the row direction and the Y-axis direction as the column direction.

  That is, the first lightness information acquisition pattern α1 is a halftone pattern of lightness 30 to 70 that can easily recognize density unevenness formed by turning on and off all the light emitting portions of the print head PH in time series.

  The first reference pattern β1 is a line-shaped white pattern extending in the Z-axis direction and having a width in the Y-axis direction of two pixels, as can be seen from FIG. 19 and FIG. is there. That is, the first reference pattern β1 is formed by always turning off the two light emitting units arranged in the center in the Y-axis direction.

  As can be seen from FIG. 19 and FIG. 20B, which is an enlarged view of the B portion in FIG. 19, the end reference pattern γ1a extends in the Z-axis direction, and the width in the Y-axis direction is a line shape corresponding to two pixels. Black pattern. That is, the end reference pattern γ1a is formed by always lighting two light emitting units arranged at the −Y side end.

  As can be seen from FIG. 19 and FIG. 20C, which is an enlarged view of the portion C in FIG. 19, the end reference pattern γ1b extends in the Z-axis direction and has a line shape corresponding to two pixels in the Y-axis direction. Black pattern. That is, the end reference pattern γ1b is formed by always lighting two light emitting units arranged at the end on the + Y side.

  As shown in FIG. 19, the second pattern Q2 includes a second brightness information acquisition pattern α2, and an end reference pattern γ2a adjacent to the −Y side end of the second brightness information acquisition pattern α2. And an end reference pattern γ2b adjacent to the + Y side end of the second brightness information acquisition pattern α2. Hereinafter, when the two end reference patterns γ2a and γ2b are not distinguished, they are collectively referred to as an end reference pattern γ2.

  The second lightness information acquisition pattern α2 has the same configuration as the first lightness information acquisition pattern α1. The end reference pattern γ2 has the same configuration as the end reference pattern γ1. The end reference pattern γ2a has the same position in the Y-axis direction as the end reference pattern γ1a (see FIG. 19). The end reference pattern γ2b has the same position in the Y-axis direction as the end reference pattern γ1b (see FIG. 19).

  As shown in FIG. 19, the third pattern Q3 includes a third brightness information acquisition pattern α3, a second reference pattern β2 located in the center of the third brightness information acquisition pattern α3 in the Y-axis direction, Have

  The third lightness information acquisition pattern α3 has the same configuration as the first lightness information acquisition pattern α1. The second reference pattern β2 has the same configuration as the first reference pattern β1, and has the same position in the Y-axis direction (see FIG. 19).

  The pattern Q configured as described above is formed by a process similar to the series of image forming processes by the color printer 2000 described above except that only one print head PH is used.

  Specifically, the light amount adjustment circuit 3223 sends the first light amount correction data stored in the flash memory 3211 to the light source drive circuit 3221. The light source driving circuit 3221 corrects the driving signal corresponding to the image information of the pattern Q from the writing control circuit 3219 using the first light quantity correction data, and outputs the corrected driving signal to the print head PH. Note that the image information of the pattern Q is stored in the flash memory 3211 in advance.

  Then, the print head PH is driven by the drive signal corrected using the first light quantity correction data, the light from the print head PH is irradiated onto the surface of the corresponding photosensitive drum, and the pattern Q is applied to the surface of the photosensitive drum. Latent image is formed. The latent image is developed by the corresponding developing roller, and the developed pattern Q is transferred onto the recording paper W via the transfer belt 2040 and then fixed by the fixing device 2050.

  Here, as an example, the resolution of the print head PH is set to 600 dpi (dots per inch), and the pattern Q is formed on the recording paper W at a resolution of 600 dpi.

  Here, the moving direction of the portion of the recording paper W facing the scanner 2085 via the fixing device 2050 is the Z-axis direction (see FIG. 15). That is, as viewed from the scanner 2085, the pattern Q is composed of a plurality of pixels that are two-dimensionally arranged on the recording paper W in the Y-axis direction and the Z-axis direction. In other words, when viewed from the scanner 2085, the pattern Q is composed of a plurality of pixels arranged in the Z-axis direction, and is composed of a plurality of pixel rows arranged in the Y-axis direction. Note that the Z-axis direction is a direction corresponding to the rotation direction of the photoconductor drum 2030, and the Y-axis direction is a direction parallel to the longitudinal direction of the photoconductor drum 2030.

  Note that the image writing width L (the width of the effective writing area) of the print head PH is effective for the arrangement area of the plurality of light emitting units and the arrangement area of the imaging optical element 12 in consideration of resist and arrangement accuracy. For example, it is several mm longer than the writing area. That is, the area where all the dots are formed when the pattern Q is obtained is not an effective writing area but an effective image area (> effective writing area).

  The recording paper W onto which the pattern Q has been transferred via the transfer belt 2040 is conveyed while facing the scanner 2085 after the pattern Q is fixed by the fixing device 2050 (see FIG. 15).

  Therefore, in the next step S24, the scanner 2085 reads the image information of the first to third patterns Q1 to Q3 in time series. Hereinafter, the first to third patterns Q1 to Q3 are also referred to as “patterns” for convenience. Here, the second pattern Q2, the first pattern Q1, and the third pattern Q3 are read in this order. The image information of each pattern is read at 600 dpi which is the reading resolution of the scanner 2085. The reading range by the scanner 2085 is within the three broken line frames in FIG.

  In the next step S25, brightness information of each pixel column of each of the first to third patterns Q1 to Q3 is acquired.

  Specifically, the image information of the first to third patterns Q1 to Q3 is sent from the scanner 2085 to the light amount adjustment circuit 3223, and the light amount adjustment circuit 3223 obtains the brightness information of the pattern from the image information of each pattern as a pixel. Get in units. That is, the brightness information of all pixels of each pattern is acquired. Then, the light amount adjustment circuit 3223 averages the brightness information of the plurality of pixels in each pixel column of each pattern in the Z-axis direction. That is, the average value of the brightness information of a plurality of pixels in each pixel column of each pattern is obtained, and the average value is acquired as the brightness information of the pixel column.

  In this case, the range to be averaged in the Z-axis direction of each pixel column is equal to or longer than the outer peripheral length of the photosensitive drum 2030 (for example, 95 mm or more if the diameter of the photosensitive drum 2030 is 30 mm). That is, the length of each pattern in the Z-axis direction is equal to or greater than the outer peripheral length of the photosensitive drum 2030.

  For this reason, the influence of density unevenness (density fluctuation) in the Z-axis direction of each pixel column can be reduced as much as possible. In addition to the uneven rotation of the photosensitive drum 2030, the unevenness of the density in the Z-axis direction of each pixel column includes the uneven rotation of the developing roller. Among these, the outer peripheral length of the photosensitive drum 2030 that is the longest region is larger. By averaging the range in the Z-axis direction, the influence of density unevenness in the Z-axis direction can be reliably reduced.

  In FIG. 22A, the brightness distribution in the Y-axis direction of a part of the pattern Q2 obtained as described above is shown in a graph. FIG. 22B is a graph showing the brightness distribution in the Y-axis direction of a part of the pattern Q1 obtained as described above. FIG. 23 is a graph showing the brightness distribution in the Y-axis direction of a part of the pattern Q3 obtained as described above.

  22A and 22B, the position (−Y side end) where the brightness is significantly lower than the other positions is the position of the end reference pattern on the −Y side. I understand. That is, the position in the Y-axis direction (Y position) of the −Y side end reference pattern can be specified. Further, as can be seen from FIG. 24A which is a partially enlarged view of FIG. 22A or FIG. 22B, the position (Y position) of each pixel column of the end reference pattern on the −Y side. ) Can also be specified. Although illustration is omitted, similarly, there is a position where the brightness is significantly lower than the other positions at the end on the + Y side, and the position is the position of the end reference pattern on the + Y side. I understand that. Then, the Y position of each pixel column of the end reference pattern on the + Y side can be specified.

  Also, from FIGS. 22B and 22C, it can be seen that the positions where the brightness is significantly higher than the other positions are the positions of the first and second reference patterns β1 and β2. That is, the position (Y position) in the Y-axis direction of each reference pattern can be specified. Further, as can be seen from FIG. 24B which is a partially enlarged view of FIG. 22B or FIG. 22C, the position (Y position) in the Y-axis direction of each pixel column of each reference pattern is specified. Can do.

  By the way, for example, in a 1200 dpi print head, for example, the “150th and 151st” light-emitting portions counted from the light-emitting portion on the most + Y side are turned on to form the end reference pattern, and the central portions “5100th and 5101” are formed. When the reference pattern is formed by turning off the “th” light emitting portion, the position indicated by the broken line arrow in FIG. 24A is the position corresponding to the 151st light emitting portion, and the broken line arrow in FIG. It can be seen that the position indicated by is the position of the 5100th light emitting section.

  In this case, the interval between the 151st light emitting part and the 5100th light emitting part is (5100-151) × 0.021 mm = 103.929 mm, and the pixel column corresponding to the 151st light emitting part and the 5100th light emitting part The distance from the pixel row corresponding to is also 103.929 mm.

  However, in reality, there is a possibility that the recording paper W expands and contracts by about ± 0.5% due to environmental fluctuations such as temperature and humidity in the image forming process, and the interval becomes 103.409 mm to 104.449 mm. This expansion / contraction amount corresponds to 25 light emitting unit intervals. That is, the light emitting unit interval and the pixel column interval may be different. The “light emitting part interval” means the distance between the centers of two adjacent light emitting parts. “Pixel column interval” means the interval between the centers of two adjacent pixel columns.

  Therefore, an interval M1 (see FIG. 15) between the first reference pattern β1 and the end reference pattern γ1a is obtained, and the −Y side light emitting part of the two light emitting parts (always off) corresponding to the first reference pattern β1 It is obtained by dividing the interval M1 by the number obtained by adding 1 to the number of the plurality of light emitting units located between the + Y side light emitting units among the two light emitting units (always lit) corresponding to the end reference pattern γ1a. Get the value m1.

  20B, for example, the pixel column numbers of the first pattern Q1 are 1, 2, 3,... From the -Y side, and the two pixel columns of the end reference pattern γ1a are If the Y position is Y1, Y2 from the -Y side, the Nth (N is a natural number) pixel column (N is a natural number) counted from the most -Y side pixel column (first pixel column) in the first brightness information acquisition pattern α1 ( Hereinafter, the Y position of the Nth pixel column) can be expressed as Y2 + N × m1. In this case, the brightness information of the Nth pixel column is the brightness information at the Y position (Y2 + N × m1) (see FIG. 22B).

  Therefore, among the two pixel columns of the end reference pattern γ1a, the Nth light emitting unit counted from the light emitting unit (first light emitting unit) adjacent to the + Y side of the light emitting unit corresponding to the pixel column on the + Y side and the above-mentioned first light emitting unit. The N pixel columns are associated with each other.

  Similarly, an interval M2 (see FIG. 15) between the first reference pattern β1 and the end reference pattern γ1b is obtained, and the + Y side light emitting part of the two light emitting parts (always off) corresponding to the first reference pattern β1 It is obtained by dividing the interval M2 by the number obtained by adding 1 to the number of the plurality of light emitting units located between the light emitting units on the −Y side among the two light emitting units (always lit) corresponding to the end reference pattern γ1b. Get the value m2.

  For example, when the pixel column number of the first pattern Q1 is 1, 2, 3,... From the + Y side, and the Y positions of the two pixel columns of the end reference pattern γ1b are Y1 ′ and Y2 ′ from the + Y side. The Y position of the Kth (K is a natural number) pixel column (hereinafter also referred to as the Kth pixel column) counted from the most + Y side pixel column (first pixel column) in the first brightness information acquisition pattern α1 Can be expressed as Y2′−K × m2. In this case, the brightness information of the Kth pixel column is the brightness information at the Y position (Y2′−K × m2).

  Therefore, among the two pixel columns of the end reference pattern γ1b, the Kth light emitting unit counted from the light emitting unit (first light emitting unit) adjacent to the −Y side of the light emitting unit corresponding to the pixel column on the −Y side; The K-th pixel column is associated.

  As described above, even when the recording paper W expands and contracts, the brightness information of each pixel column of the first brightness information acquisition pattern α1 and the light emitting unit used for forming the pixel column are accurately associated (matched). )be able to.

  In the next step S29, the brightness information of each pixel column corresponding to the first reference pattern β1 of the second brightness information acquisition pattern α2 is acquired. Specifically, the brightness information of two pixel columns at the same Y position as the two pixel columns of the first reference pattern β1 of the second brightness information acquisition pattern α2 is acquired.

  Note that the Y position of the second brightness information acquisition pattern α2 corresponding to the Y position of the two pixel columns of the first reference pattern β1 (Y position of the center two pixel columns of the second brightness information acquisition pattern α2). May be obtained based on the two end reference patterns γ2a and γ2b, and the obtained lightness information at the Y position may be obtained as the lightness information of the two pixel columns of the first reference pattern β1. That is, for example, the Y position of two adjacent pixel columns is obtained at an intermediate position between the two end reference patterns γ2a and γ2b, and the brightness information of the Y position is used as the brightness information of the two pixel columns of the first reference pattern β1. You may get it. In this case, even if the Y position of the end reference patterns γ1 and γ2 and the position around the X axis are relatively displaced, each pixel column of the first reference pattern β1 and the light emitting unit used for forming the pixel column Can be accurately associated.

  In the next step S31, the brightness information of each pixel column corresponding to each end reference pattern γ1 of the third brightness information acquisition pattern α2 is acquired. Specifically, the brightness information of the two pixel columns at the same Y position as the two pixel columns of each end reference pattern γ1 of the third brightness information acquisition pattern α3 is acquired.

  For example, brightness information at the Y position that is separated by (M1 + M2) / 2 from the second reference pattern β2 to the + Y side and −Y side is acquired as brightness information of the two end reference patterns γ1a and γ1b. Also good. In this case, even if the Y position and the position around the X axis of the first and second reference patterns β1 and β2 are relatively shifted, each pixel column of each end reference pattern γ1 and the pixel column are formed. It is possible to accurately associate the light emitting units.

  As described above, the brightness information of all the pixel columns of the first pattern Q1 can be acquired.

  Therefore, in the next step S33, second light amount correction data for correcting the light emission amounts of the plurality of light emitting units is created based on the lightness information of all the pixel columns of the first pattern Q1. The second light amount correction data is data including light amount correction values of a plurality of light emitting units.

  In this case, the second light quantity correction data is created so that the difference in lightness information of all the pixel columns of the first pattern Q1 is reduced, that is, the change of the lightness information in the Y-axis direction is reduced. More specifically, the second light quantity correction data is such that the brightness information of all the pixel columns of the first pattern Q1 is equal, and more specifically, the brightness information of each pixel column is the average value (Ave) of the brightness information of all the pixel columns. For example, 42).

  Specifically, using the following equation (1), the light amount correction of the light emitting unit corresponding to the pixel column is performed so that the brightness value U of each pixel column becomes the average value Ave of the brightness information of all the pixel columns. The value J is calculated.

  Light amount correction value J = (Ave−U) × k (1)

  Here, k is referred to as a light quantity conversion factor, and the sign is negative. That is, in order to increase the brightness, the amount of light is reduced (current is reduced). k is obtained by acquiring a lightness change amount with respect to a light amount change (adjustment) amount in advance and deriving a function of the light amount change amount with respect to the lightness change amount.

  More specifically, in FIG. 25A, the relationship between the light amount (light emission amount) and the brightness at the light emitting portion is shown in a graph for each color (examples of K, M, C, and Y). The brightness light quantity conversion coefficient k can be derived from the graph (here, only the K graph is used, and the M, C, and Y graphs are not used and are shown for comparison.

  Here, a test pattern including eight regions T1 to T8, each of which is the same pattern as the brightness information acquisition pattern, is arranged in the Z-axis direction on a single sheet of recording paper shown in FIG. Is formed. In this test pattern, when T1 to T8 are formed, the lightness of the light emitting portion (light emission amount) is made different from each other, thereby making the brightness at T1 to T8 different from each other. Here, from T1 to T8, the amount of emitted light is gradually decreased and the brightness is gradually increased. The lightness of this test pattern is measured with a lightness meter and plotted as shown in FIG. At this time, the average brightness value obtained by averaging the brightness of all the pixels in the respective regions T1 to T8 is plotted. By performing this averaging process, it is possible to eliminate factors other than the amount of emitted light (exposure amount) (uneven charging or uneven development in the color printer 2000) from affecting the brightness, and to obtain a highly accurate approximation function. For example, a scanner is used as the brightness measuring device.

  Here, the light quantity conversion coefficient k has a linear function approximation as an approximation function, and a light quantity conversion coefficient k = −3.3.

  In FIG. 25A, as an example of other colors, straight lines (broken lines) of linear functions are shown for M, C, and Y as in K (plotting is omitted). At this time, the light quantity conversion coefficient k is M-3.6, C is -3.8, and Y is -4.2. It is practically difficult to carry out in the production process because image output and lightness measurement with patterns are complicated and time-consuming. Therefore, the lightness light quantity conversion coefficient k common to each color is used without obtaining the lightness light quantity conversion coefficient k for each color. Here, the conversion coefficient k = −3.3 is commonly used for each color. This lightness light quantity conversion coefficient k is a color having the smallest light quantity adjustment amount with respect to a change in lightness among the colors (the linear function approximation straight line has the slowest slope), that is, the smallest conversion coefficient (absolute value). ing. The reason why the conversion coefficient k is commonly used is that the difference in the four colors is as small as about 27% (= {4.2-3.3} /3.3) in the first place, Because the influence is small. In M, C, and Y, the light quantity correction value is lower than ideal (27% reduction in Y), but there is no problem as practical image correction. On the other hand, if Y-4.2, which has the maximum conversion coefficient among the four colors, is used in common, the light amount correction value becomes higher than ideal in K, M, and C, and the image density is warped by overcorrection. Unevenness (vertical stripes) will be emphasized.

  In the next step S34, the third light quantity correction data is created by superimposing the second light quantity correction data on the first light quantity correction data. That is, the light amount correction data of each light emitting unit in the third light amount correction data is obtained by adding the correction data of the light emitting unit in the second light amount correction data to the light amount correction data of each light emitting unit in the first light amount correction data.

  In the next step S35, a test image is formed on the recording paper using the third light quantity correction data. The test image is formed by a process similar to the image forming process described above.

  In the next step S37, it is determined whether or not the PV (Peak to Valley) value of the brightness information of the test image is 2 or less. Specifically, the image information of the test image is read by the scanner 2085, the lightness distribution is acquired from the image information, and the lightness information in each region of a predetermined width (for example, 2 mm) adjacent to the lightness distribution in the Y-axis direction. To determine whether the PV value of at least one region is greater than or equal to a reference value (for example, 2). That is, it is determined whether vertical stripes that can be visually recognized are generated in the output image. If the determination in step S37 is negative, the process returns to step S23. That is, the series of steps S23 to S35 described above are repeated until the PV value of the brightness information of the test image becomes 2 or less. On the other hand, if the determination in step S37 is affirmative, the process proceeds to step S39.

  In step S39, the third light quantity correction data is stored in the flash memory 3211. When step S39 is executed, the flow ends.

  Then, after the flow is completed, for example, when there is a print request from the host device such as a personal computer to the color printer 2000, the third light amount correction data is sent from the light amount adjustment circuit 3223 to the light source drive circuit 3221, and the light source drive circuit 3221 The drive signal of each light emitting unit modulated based on the image information from the control circuit 3219 is corrected using the light amount correction value corresponding to the light emitting unit, and the corrected drive signal is output to the light emitting unit.

  As described above, the light amount correction data of the print head PH of each station is created and stored, and when printing is performed, the light amount of the print head PH is adjusted using the third light amount correction data.

  As a result, a high-quality color image can be formed on the recording paper.

  The above-described light amount adjustment of the print head PH may be appropriately performed by an operator, a serviceman user, or the like via the operation unit at the time of manufacturing, shipping, maintenance, or the like of the color printer 2000, for example. For example, it may be automatically performed based on, for example, temperature, humidity, the number of times of printing, or periodically.

  The light amount adjustment of the print head PH is preferably performed at K, M, and C other than Y and T, which are difficult to visually recognize. Although it may be executed with Y and T, it is difficult to perceive visually, so there is less influence than other colors and there is no problem in practical use. By not executing with Y and T, cost reduction is achieved by shortening the process. be able to.

  26A to 26D show patterns (reference images) having different pixel densities (resolutions). In FIG. 26A, each of the four portions of the unit light emission pattern is composed of 4 × 4 pixels (4 dot pairs). In FIG. 26 (B), each of the four portions of the unit light emission pattern is composed of a 3 × 3 image (3 dot pairs). In FIG. 26C, each of the four portions of the unit light emission pattern is composed of 2 × 2 pixels (two-dot pairs). In FIG. 26D, each of the four portions of the unit light emission pattern is composed of 1 × 1 pixels (one dot pair). In FIGS. 26A to 26D, one of the four portions of the unit light emission pattern is composed of at least one halftone pixel, and the other three portions are at least one white pixel. Although configured, the reverse is also possible.

  FIG. 27 shows the result of visual evaluation of how much vertical stripes are reduced as an image after correction due to the difference between the reference images shown in FIGS. 26 (A) to 26 (D). From FIG. 27, it can be seen that the correction effect varies depending on the resolution of the reference image. From this result, if the resolution specification is a specification that eliminates vertical stripes, for example, with a resolution of FIG. 26B or lower, the resolution of FIG. 26C or FIG. Is preferred.

  In FIG. 19, each reference pattern is located at the center of the pattern Q in the Y-axis direction, but may be located at a position other than the center of the pattern Q in the Y-axis direction and other than the end. Further, the end reference pattern may be shifted to some extent (for example, about 10 mm) toward the center side in the Y-axis direction of the pattern Q. Furthermore, the reference pattern is not limited to a white line (always off), but may be a halftone line or a black line (always on), but the line pattern has a brightness difference of 10 or more with respect to the average brightness (eg 42). Can be recognized as a reference pattern, which is preferable. In FIG. 19, a white line with a high brightness difference is adopted as the reference pattern.

  Since the position of the edge reference pattern and the corresponding light emitting portion can be specified, and the position of the reference pattern and the corresponding light emitting portion can be specified, the recording paper W is inclined at the time of image formation, or at the time of reading by the scanner 2085. Even when the recording paper W is inclined and each end reference pattern or each reference pattern is inclined with respect to the Z axis, each pixel column is accurately associated with the light emitting unit used to form the pixel column ( Match).

  In the other embodiment, the brightness information of the pixel column corresponding to the end reference pattern of the third pattern Q3 is acquired, and the light emitting unit correction corresponding to the end reference pattern is performed based on the brightness information. Data is created, but it is not limited to this. Since the brightness unevenness of the edge reference pattern (lightness unevenness of the pattern edge) is harder to recognize than the brightness unevenness at the center of the pattern, for example, correction of the light emitting part corresponding to the edge reference pattern included in the first light quantity correction data The light amount of the corresponding light emitting unit may be corrected using the data. In this case, when the second light quantity correction data is created, it is not necessary to create light-emitting portion correction data corresponding to the edge reference pattern.

  In the other embodiments described above, each pixel column of the first brightness information acquisition pattern α1 and the light emitting unit used for forming the pixel column correspond to the end reference pattern γ1 and the end reference pattern γ1. However, instead of this, for example, the first reference pattern β1 and the light emitting unit corresponding to the reference pattern β1 may be associated with each other as a reference.

  In the other embodiment, the interval between the end reference pattern and the reference pattern is obtained, and the interval is divided equally to be used for forming each pixel column of the first brightness information acquisition pattern α1 and the pixel column. However, the present invention is not limited to this. For example, the Y position of each pixel column of the first reference pattern β1 is adjusted to coincide with the Y position of the light emitting unit corresponding to the pixel column, and the Y position of each pixel column of the end reference pattern γ1 is set to the pixel. By adjusting to match the Y position of the light emitting unit corresponding to the column, and interpolating or thinning out the pixel column between the first reference pattern β1 and the end reference pattern γ1, the pixel column and the pixel column The light emitting part used for formation may be associated.

  Further, as shown in FIG. 28, a pattern R (reference image) including the first pattern R1 and the second pattern R2 is formed on the recording paper W, and brightness information of each pixel column of the pattern R is acquired. The second light amount correction data may be created, the third light amount correction data may be created and stored, and the light amount of the print head PH may be adjusted using the third light amount correction data.

  Specifically, the first pattern R1 has the same configuration as the first pattern Q1. The second pattern R2 has the same configuration as the first to third brightness information acquisition patterns α1 to α3. That is, the second pattern R2 is a halftone solid pattern.

  Hereinafter, the light amount correction method of the print head PH using the pattern R as a reference image is performed according to the flowchart of FIG. 29 as an example. The light amount adjustment method here is the same as the light amount adjustment method of the other embodiment described above, the brightness information at the position corresponding to the first reference pattern β1 in the second pattern Q2 and the end reference pattern γ1 in the third pattern Q3. Brightness information at a position corresponding to is acquired (steps S29 and S31), whereas brightness information at positions corresponding to the first reference pattern β and each end reference pattern γ1 in the second pattern R2 is obtained. The acquired points (steps S49 and S51) are different. That is, steps S41 to S47 are the same as steps S21 to S27 in FIG. 18, and steps S53 to S59 are the same as steps S33 to S39 in FIG.

  The configuration of the patterns Q and R described above can be changed as appropriate according to, for example, the specifications of the print head PH. For example, the arrangement order of the first to third patterns Q1 to Q3 in the pattern Q and the arrangement order of the first and second patterns R1 and R2 in the pattern R can be changed as appropriate. Each lightness information acquisition pattern has halftone pixels, but may instead have black pixels.

  In the other embodiment, the brightness information of all the pixel columns of the second pattern Q2 of the pattern Q is acquired, but each of the second brightness information acquisition patterns α2 corresponding to the first reference pattern β1 is acquired. Only brightness information of a part of pixel columns including the pixel column may be acquired. Further, in the other embodiment, the brightness information of all the pixel columns of the third pattern Q3 of the pattern Q is acquired, but corresponds to each end reference pattern γ1 of the third brightness information acquisition pattern α3. Only brightness information of a part of pixel columns including each pixel column may be acquired. In the example shown in FIGS. 28 and 29, the brightness information of all the pixel columns of the second pattern R2 of the pattern R is acquired. However, the reference pattern β1 and each end reference of the second pattern R2 are acquired. Only the brightness information of some pixel columns including each pixel column corresponding to the pattern γ1 may be acquired.

  Further, the order of steps S27 to S31 in FIG. 18 can be changed as appropriate, and the order of steps S47 to S51 in FIG. 29 can be changed as appropriate.

  Further, the brightness information acquisition pattern including a plurality of unit light emission patterns arranged in a staggered pattern used for the light amount adjustment of the print head of the other embodiment is used for the light amount adjustment of the print head of the one embodiment. May be.

  16b: Organic EL element (light emitting unit), 100: First reference pattern (reference pattern), 150: First brightness information acquisition pattern, 200: Second reference pattern (another reference pattern), 250: Second brightness information Acquisition pattern, 1000 ... laser printer (image forming apparatus), 1085 ... scanner (image reading means), 2000 ... color printer (image forming apparatus), 2085 ... scanner (image reading means), 2200 ... print head, 2200a to 2200d ... print head, P1 ... first pattern, P2 ... second pattern, Q1 ... first pattern, Q2 ... second pattern, R1 ... first pattern, R2 ... second pattern, PH ... printhead , W: recording paper (recording medium), α1: first lightness information acquisition pattern, α2: second lightness information acquisition pattern, α3... third lightness information acquisition pattern, β1... first reference pattern, β2... second reference pattern, γ1 (γ1a, γ1b), γ2 (γ2a, γ2b).

JP 2004-188665 A

Claims (21)

A method for adjusting the amount of light of a print head having a plurality of light emitting units,
The plurality of light emitting units are arranged so that positions in a uniaxial direction are different from each other,
A recording medium transported in a direction orthogonal to the uniaxial direction includes a first lightness information acquisition pattern and a reference pattern positioned inside the first lightness information acquisition pattern using the print head. A pattern forming step of arranging a pattern and a second pattern including a second lightness information acquisition pattern in a direction perpendicular to the uniaxial direction;
A first brightness information acquisition step of acquiring first brightness information at each position in the uniaxial direction of the first brightness information acquisition pattern;
A second brightness information acquisition step of acquiring second brightness information at a position corresponding to at least the position of the reference pattern in the uniaxial direction of the second brightness information acquisition pattern;
The light emitting unit corresponding to the first lightness information acquisition pattern among the plurality of light emitting units, with the light emitting unit corresponding to the reference pattern of the plurality of light emitting units and the reference pattern as a reference, and the first A first association step for associating each position in the uniaxial direction of the lightness information acquisition pattern;
A first light emission amount adjustment step of adjusting a light emission amount of a light emitting unit corresponding to each position in the uniaxial direction of the first lightness information acquisition pattern among the plurality of light emitting units based on the first lightness information; ,
And a second light emission amount adjustment step of adjusting a light emission amount of the light emitting unit corresponding to a position in the uniaxial direction of the reference pattern among the plurality of light emitting units based on the second lightness information. How to adjust the light intensity of the head. The second pattern includes, in the second lightness information acquisition pattern, another reference pattern that is different in position in the uniaxial direction from the reference pattern,
Prior to the second light emission amount adjustment step, the position of the second lightness information acquisition pattern in the uniaxial direction of the second lightness information acquisition pattern with reference to the light emitting unit corresponding to the other reference pattern and the other reference pattern The print head light amount adjusting method according to claim 1, further comprising: a second association step of associating a position corresponding to the light emitting portion corresponding to the reference pattern among the plurality of light emitting portions. . The plurality of light emitting units are arranged at predetermined intervals with respect to the uniaxial direction,
In the first and second brightness information acquisition steps, the first and second patterns are read at predetermined reading intervals by an image reading unit, respectively, and the first and second patterns are read from the read first and second patterns, respectively. 1 and 2 brightness information is acquired,
The method according to claim 2, wherein the reading interval is larger than the predetermined interval.   The method according to claim 3, wherein the reading interval is an integral multiple of the predetermined interval. The first pattern is formed by turning on a light emitting unit corresponding to the first lightness information acquisition pattern at least once, and constantly turning on or off a light emitting unit corresponding to the reference pattern,
The second pattern is formed such that at least a light emitting unit corresponding to the reference pattern is turned on at least once, and a light emitting unit corresponding to the other reference pattern is always turned on or off. 5. The method for adjusting a light amount of a print head according to claim 3, wherein the light amount is adjusted.   The first and second lightness information acquisition patterns are a plurality of pixels arranged in a matrix of n rows and n columns in which the row direction is a direction orthogonal to the uniaxial direction and the column direction is the uniaxial direction, respectively. The print head light quantity adjusting method according to claim 3, comprising a plurality of square patterns arranged in a staggered pattern.   The method for adjusting the amount of light of a print head according to claim 6, wherein the length of one side of each of the plurality of square patterns is larger than the reading interval. The reference pattern and the another reference pattern are linear patterns extending in a direction orthogonal to the uniaxial direction,
8. The method of adjusting a light amount of a print head according to claim 6, wherein the reference pattern, the another reference pattern, and the plurality of square patterns have the same width in the uniaxial direction.   The cycle including the pattern formation step, the first and second lightness information acquisition steps, the first association step, and the first and second light emission amount adjustment steps is performed a plurality of times. The light quantity adjustment method of the print head as described in any one of -8. The first pattern further includes an end reference pattern adjacent to the end in the uniaxial direction of the first brightness information acquisition pattern,
In the first associating step, the first brightness information of the plurality of light emitting units based on the light emitting unit corresponding to the end reference pattern and the end reference pattern of the plurality of light emitting units. The light quantity of the print head according to any one of claims 1 to 9, wherein a light emitting unit corresponding to the acquisition pattern is associated with each position in the uniaxial direction of the first lightness information acquisition pattern. Adjustment method. In the second lightness information acquisition step, another second lightness information that is lightness information at a position corresponding to the position in the uniaxial direction of the end portion reference pattern of the second lightness information acquisition pattern is acquired,
In the second light emission amount adjustment step, the light emission amount of the light emitting unit corresponding to the position in the uniaxial direction of the end portion reference pattern among the plurality of light emitting units is adjusted based on the second second lightness information. The method of adjusting a light amount of a print head according to claim 10. In the pattern formation step, the first and second patterns, and the third pattern including the third lightness information acquisition pattern are arranged in a direction perpendicular to the uniaxial direction,
The second pattern further includes another end reference pattern adjacent to the end in the uniaxial direction of the second lightness information acquisition pattern,
The third pattern further includes another reference pattern inside the third lightness information acquisition pattern,
The position in the uniaxial direction of the reference pattern and the further another reference pattern is the same,
The position in the uniaxial direction of the end reference pattern and the another end reference pattern are the same,
The third brightness information acquisition step of acquiring third brightness information at a position corresponding to at least the position of the end reference pattern in the uniaxial direction of the third brightness information acquisition pattern. The light quantity adjustment method of the print head of 10.   13. The method according to claim 12, further comprising a third light emission amount adjustment step of adjusting a light emission amount of the light emitting unit corresponding to the position in the uniaxial direction of the end portion reference pattern based on the third brightness information. To adjust the light amount of the print head. The lightness information acquisition pattern includes a plurality of unit light emission patterns arranged in a staggered pattern,
Each of the plurality of unit light emission patterns has four portions arranged in a matrix of 2 rows and 2 columns with the direction perpendicular to the uniaxial direction as the row direction and the uniaxial direction as the column direction,
One of the four parts is formed by turning on at least one light emitting part, and the other three parts are formed by turning off at least one light emitting part, or the four parts The one of the two portions is formed by turning off at least one light emitting portion, and the other three portions are formed by turning on at least one light emitting portion. The method for adjusting the light amount of the print head according to any one of claims 13 to 14. An image carrier;
An image formation comprising: a print head whose light amount is adjusted by the light amount adjustment method for a print head according to claim 1, wherein the image carrier is irradiated with light modulated in accordance with image information. apparatus. An image comprising: an image carrier; and a print head having a plurality of light emitting units arranged so that positions in one axis direction are different from each other, and irradiating the image carrier with light modulated in accordance with image information A method for manufacturing a forming apparatus, comprising:
A first medium including a reference pattern and a first lightness information acquisition pattern and a second lightness information acquisition pattern using the print head on the recording medium conveyed in the direction orthogonal to the uniaxial direction. A pattern forming step of arranging two patterns in a direction orthogonal to the uniaxial direction;
A first brightness information acquisition step of acquiring first brightness information at each position in the uniaxial direction of the first brightness information acquisition pattern;
A second brightness information acquisition step of acquiring second brightness information at a position corresponding to at least the position of the reference pattern in the uniaxial direction of the second brightness information acquisition pattern;
Acquisition of the first brightness information of the plurality of light emitting units based on the position of the light emitting unit corresponding to the reference pattern in the plurality of light emitting units in the uniaxial direction and the position of the reference pattern in the uniaxial direction. A first associating step for associating the light emitting unit corresponding to the pattern for use with each position in the uniaxial direction of the first lightness information acquisition pattern;
A first light emission amount adjustment step of adjusting a light emission amount of a light emitting unit corresponding to each position in the uniaxial direction of the first lightness information acquisition pattern among the plurality of light emitting units based on the first lightness information; ,
An image including at least a second light emission amount adjustment step of adjusting a light emission amount of the light emitting unit corresponding to a position in the one-axis direction of the reference pattern among the plurality of light emitting units based on the second lightness information. Manufacturing method of forming apparatus. The second pattern includes, in the second lightness information acquisition pattern, another reference pattern that is different in position in the uniaxial direction from the reference pattern,
Prior to the second light emission amount adjustment step, the position of the second lightness information acquisition pattern in the uniaxial direction of the second lightness information acquisition pattern with reference to the light emitting unit corresponding to the other reference pattern and the other reference pattern 17. The method of manufacturing an image forming apparatus according to claim 16, further comprising a second association step of associating a position corresponding to the light emitting portion corresponding to the reference pattern among the plurality of light emitting portions. . The first pattern further includes an end reference pattern adjacent to the end in the uniaxial direction of the first brightness information acquisition pattern,
In the first associating step, the first brightness information of the plurality of light emitting units based on the light emitting unit corresponding to the end reference pattern and the end reference pattern of the plurality of light emitting units. 18. The method of manufacturing an image forming apparatus according to claim 16, wherein a light emitting unit corresponding to the acquisition pattern is associated with each position in the uniaxial direction of the first brightness information acquisition pattern. In the second lightness information acquisition step, another second lightness information that is lightness information at a position corresponding to the position in the uniaxial direction of the end portion reference pattern of the second lightness information acquisition pattern is acquired,
In the second light emission amount adjustment step, the light emission amount of the light emitting unit corresponding to the position in the uniaxial direction of the end portion reference pattern among the plurality of light emitting units is adjusted based on the second second lightness information. The method of manufacturing an image forming apparatus according to claim 18. In the pattern formation step, the first and second patterns, and the third pattern including the third lightness information acquisition pattern are arranged in a direction perpendicular to the uniaxial direction,
The second pattern further includes another end reference pattern adjacent to the end in the uniaxial direction of the second lightness information acquisition pattern,
The third pattern further includes another reference pattern inside the third lightness information acquisition pattern,
The position in the uniaxial direction of the reference pattern and the further another reference pattern is the same,
The position in the uniaxial direction of the end reference pattern and the another end reference pattern are the same,
The third brightness information acquisition step of acquiring third brightness information at a position corresponding to at least the position of the end reference pattern in the uniaxial direction of the third brightness information acquisition pattern. 18. A method for manufacturing the image forming apparatus according to 18.   21. The method according to claim 20, further comprising a third light emission amount adjustment step of adjusting a light emission amount of the light emitting unit corresponding to the position in the uniaxial direction of the end portion reference pattern based on the third brightness information. Manufacturing method of the image forming apparatus.