JP2009119798A - Signal generating circuit, exposure apparatus, image forming apparatus, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a signal generating circuit allowing a light emitting element to emit light according to a luminescent state around a light emitting point. <P>SOLUTION: The signal generating circuit 100 comprises a density determining part 111 determining the density of a predetermined region, composed of a plurality of pixels including light emitting pixels of acquired image data; a light quantity correction factor computing circuit 112 according to lighting rates for outputting a correction factor for correcting the light emission amount of a self-scanning type LED array (SLED) 63 corresponding to the light emitting pixels out of a plurality of self-scanning type LED arrays (SLED) 63 in which a plurality of light emitting elements are arrayed, when determining that the image data of the predetermined region include fine lines and isolated pixels as a result of determining whether the image data of the predetermined region include the fine lines and isolated pixels based on the density of the predetermined region determined by the density determining part 111; and a pulse generating circuit 115 generating a lighting signal of the amount of light emission corrected based on the correction factor outputted by the light quantity correction factor computing circuit 112 according to the lighting rates, and outputting the lighting signal to the self-scanning type LED array (SLED) 63. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a signal generation circuit, an exposure apparatus, an image forming apparatus, and a program.

  In an image forming apparatus such as a printer or a copying machine using an electrophotographic system, an apparatus using a light emitting element array in which light emitting elements such as LEDs are arranged in a line as an exposure apparatus that exposes an image carrier such as a photosensitive drum Has been proposed.

Here, as a technique described in a gazette related to an exposure apparatus using a light emitting element array, for example, there is a technique described in Patent Document 1.
In this technology, it is determined whether or not the target pixel is a part of a fine line, and if it is a fine line, the writing time is set longer than the normal writing time, and the line width is controlled with a resolution less than the pixel. The reproducibility is improved.

JP 2000-37908 A

  By the way, in the exposure apparatus using the light emitting element array, the photosensitive member is exposed by the light output from the light emitting element array, and a potential difference of a certain level or more is generated at the exposed position on the photosensitive member. Thereafter, the toner is put on the position where the potential difference is generated, and the image is output on the output paper. Here, since the light output from the light emitting element array spreads to some extent and is exposed to the photosensitive member, the potential difference generated at the light emitting point varies depending on the light emitting state around the light emitting point. For example, the exposure amount per pixel that the light emitting element array gives to the photoconductor is different even if the same lighting signal is given to the light emitting element array in a thin line or isolated pixel and a continuous pixel in which pixels such as thick lines and dark lines are densely packed. The resulting potential difference is also different.

  An object of the present invention is to provide a signal generation circuit or the like that causes a light emitting element to emit light in accordance with a light emitting state around a light emitting point.

  According to the first aspect of the present invention, a determination unit that determines a density of a predetermined region that includes a plurality of pixels including a light emitting pixel of acquired image data, and a density of the predetermined region that is determined by the determination unit. A plurality of light emitting elements in which a plurality of light emitting elements are arranged when it is determined whether the image data of the predetermined region includes thin lines or isolated pixels based on the image data and the image data includes thin lines or isolated pixels. A light emission amount correcting unit that outputs a correction coefficient for correcting the light emission amount of the light emitting element array member corresponding to the light emitting pixel among the array members, and a correction based on the correction coefficient output by the light emission amount correcting unit. A signal generation circuit comprising: a lighting signal output means for generating a lighting signal of the amount of emitted light and outputting it to the light emitting element array member.

According to a second aspect of the present invention, the light emission amount correcting means is compared with a predetermined threshold relating to density used when determining whether or not the image data of the predetermined area includes a thin line or an isolated pixel. When the density of the predetermined region determined by the determination unit is small, the light emission amount of the light emitting element array member corresponding to the light emitting pixel in the predetermined region is corrected to a value larger than the original light emission amount of the light emitting pixel. The signal generation circuit according to claim 1, wherein a correction coefficient to be output is output.
According to a third aspect of the present invention, in the signal generation circuit according to the first aspect, the determination unit determines the density of the predetermined region based on the number of the light emitting pixels in the predetermined region. is there.
According to a fourth aspect of the present invention, there is provided a storage unit that stores a variation correction coefficient that corrects a variation in light amount of each of the plurality of light emitting element array members, the correction coefficient output by the light emission amount correction unit, and the Lighting signal calculation means for calculating and outputting either a current value or a pulse width of the lighting signal of the light emitting element array member corresponding to the light emitting pixel based on the variation correction coefficient stored in the storage means; The signal generation circuit according to claim 1, further comprising:

  The invention according to claim 5 includes a plurality of light emitting element array members in which a plurality of light emitting elements are arranged, and a signal generation circuit, wherein the signal generation circuit includes a plurality of pixels including a light emission pixel of acquired image data. Determining means for determining the density of the predetermined area based on the number of light-emitting pixels in the predetermined area, and the density of the predetermined area determined by the determining means indicates that the image data of the predetermined area is a thin line And the light emitting element array member corresponding to the light emitting pixel in the predetermined region when the light emitting element is smaller than the predetermined threshold with respect to the density used when determining whether or not the pixel includes an isolated pixel. A light emission amount correcting means for outputting a correction coefficient for correcting the light emission amount to a value larger than the original light emission amount of the light emitting pixel, and a variation for correcting variation in the light amount of each of the plurality of light emitting element array members. The light emitting element array member corresponding to the light emitting pixel based on the storage means for storing the correction coefficient, the correction coefficient output by the light emission amount correcting means, and the variation correction coefficient stored in the storage means A lighting signal calculation means for calculating and outputting either the current value of the lighting signal to the light source or the number of times of light emission, and generating a light emission amount lighting signal based on the output of the lighting signal calculation means to the light emitting element array member An exposure apparatus comprising a lighting signal output means for outputting.

According to a sixth aspect of the present invention, the lighting signal calculation unit is configured to emit the light emission based on one of the correction coefficient output from the light emission amount correction unit and the variation correction coefficient stored in the storage unit. A current value calculation circuit that calculates and outputs a current value of the lighting signal to the light emitting element array member corresponding to the pixel, and calculates a pulse width of the lighting signal based on the other of the correction coefficient and the variation correction coefficient The exposure apparatus according to claim 5, further comprising a pulse width calculation circuit that outputs the same.
According to a seventh aspect of the present invention, when the density of the predetermined region is greater than a predetermined value, the light emission amount correcting unit calculates the light emission amount of the light emitting element array member corresponding to the light emitting pixel in the predetermined region. 6. The exposure apparatus according to claim 5, wherein a correction coefficient for correcting the light emission pixel to a value smaller than the original light emission amount is output.

  According to an eighth aspect of the present invention, an image holding member, an image processing unit that performs predetermined image processing on image information acquired from the outside and outputs the image information, and a plurality of light emitting elements are arranged, and the image holding unit is arranged. Based on the number of light emitting pixels in a predetermined area composed of a plurality of light emitting element array members that irradiate light to the body and a plurality of pixels including the light emitting pixels of the image data acquired from the image processing means. Determining means for determining density, and the density of the predetermined area determined by the determining means relates to a density used when determining whether the image data of the predetermined area includes a thin line or an isolated pixel; When smaller than the predetermined threshold value compared with the predetermined threshold value, the light emission amount of the light emitting element array member corresponding to the light emitting pixel in the predetermined region is larger than the original light emission amount of the light emitting pixel. Output by a light emission amount correcting means for outputting a correction coefficient to be corrected, a storage means for storing a variation correction coefficient for correcting a variation in light quantity of each of the plurality of light emitting element array members, and a light emission amount correcting means. Lighting that calculates and outputs either the current value of the lighting signal to the light emitting element array member corresponding to the light emitting pixel or the number of times of light emission based on the correction coefficient and the variation correction coefficient stored in the storage unit A signal calculation unit; and a lighting signal output unit that generates a lighting signal corresponding to the image data acquired from the image processing unit based on an output of the lighting signal calculation unit and outputs the lighting signal to the plurality of light emitting element array members. An image forming apparatus including the image forming apparatus.

  The invention according to claim 9 is a determination function for determining, based on the number of luminescent pixels in a predetermined area composed of a plurality of pixels including a luminescent pixel of acquired image data, on a computer, When the density of the predetermined area is smaller than the predetermined threshold compared to a predetermined threshold relating to the density used when determining whether the image data of the predetermined area includes a thin line or an isolated pixel. A light emission amount correction function for outputting a correction coefficient for correcting the light emission amount of the light emitting element array member corresponding to the light emission pixel in the predetermined region to a value larger than the original light emission amount of the light emission pixel, the correction coefficient, The variation correction coefficient stored in the storage means for storing the variation correction coefficient for correcting the variation in the amount of light of each of the plurality of light emitting element array members in which the plurality of light emitting elements are arranged. Zui and a program for realizing the lighting signal calculation function that calculates and outputs one of the current value and the number of emission of the lighting signals of the light emitting element array members corresponding to the light emitting pixel.

According to the first aspect of the present invention, low gradation image data such as thin lines and isolated pixels can be output with good reproducibility.
According to the second aspect of the present invention, it can be determined with a simple configuration whether or not the light emitting element corresponds to a thin line or an isolated pixel.
According to the third aspect of the present invention, the concentration around the light emitting element can be determined with a simple circuit configuration.
According to the invention concerning Claim 4, compared with the case where it does not have this structure, the exposure amount of the light emitting element array member can be accurately output in consideration of the variation in the light amount.
According to the fifth aspect of the present invention, low gradation image data such as thin lines and isolated pixels can be output with good reproducibility.
According to the sixth aspect of the present invention, it is possible to accurately output the exposure amount of the light emitting element array member in consideration of the variation in the amount of light as compared with the case where the present configuration is not provided.
According to the seventh aspect of the present invention, non-light emitting points included in a high gradation image can be output with good reproducibility.
According to the eighth aspect of the invention, it is possible to output low gradation image data such as thin lines and isolated pixels with high reproducibility.
According to the ninth aspect of the invention, it is possible to output low gradation image data such as thin lines and isolated pixels with high reproducibility.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a diagram showing an overall configuration of an image forming apparatus 1 using an LED print head which is an example of an exposure apparatus according to the present embodiment.
An image forming apparatus 1 shown in FIG. 1 is a so-called tandem type digital color printer.
The image forming apparatus 1 includes an image forming process unit 10 that forms an image corresponding to image information of each color, a control unit 30 that controls the operation of the image forming apparatus 1, and a personal computer (PC) 2 or an image reading device, for example. And an image processing unit 40 as an example of an image processing unit that performs predetermined image processing on image information received from these and outputs the image information as image data.

The image forming process unit 10 includes four image forming units 11Y, 11M, 11C, and 11K (hereinafter collectively referred to simply as “image forming unit 11”) that are arranged in parallel at regular intervals. Yes.
Each image forming unit 11 includes a photosensitive drum 12 as an example of an image holding member that forms an electrostatic latent image and holds a toner image, and a charger that uniformly charges the surface of the photosensitive drum 12 with a predetermined potential. 13 and an LED print head (LPH) 14 as an example of an exposure device that exposes the photosensitive drum 12 charged by the charger 13 based on image data. Each image forming unit 11 includes a developing unit 15 that develops the electrostatic latent image formed on the photosensitive drum 12 and a cleaner 16 that cleans the surface of the photosensitive drum 12 after transfer.

Here, each image forming unit 11 is configured in substantially the same manner except for the color of the toner stored in the developing device 15. Each image forming unit 11 forms yellow (Y), magenta (M), cyan (C), and black (K) toner images.
In addition, the image forming process unit 10 intermediates each color toner image of each image forming unit 11 and the intermediate transfer belt 21 onto which the toner images of each color formed on the photosensitive drum 12 of each image forming unit 11 are transferred in a multiple manner. A primary transfer roll 22 that sequentially transfers (primary transfer) to the transfer belt 21 and a superimposed toner image transferred onto the intermediate transfer belt 21 are collectively transferred (secondary transfer) onto a sheet P that is a recording material (recording paper). A secondary transfer roll 23 and a fixing device 25 for fixing the secondary transferred image on the paper P are provided.

  In the image forming apparatus 1 of the present embodiment, the image forming process unit 10 performs an image forming operation based on a control signal such as a synchronization signal supplied from the control unit 30. At that time, the image data input from the PC 2 or the image reading device 3 is subjected to image processing by the image processing unit 40 and supplied to each image forming unit 11 via the interface. In the yellow image forming unit 11Y, for example, the surface of the photosensitive drum 12 uniformly charged at a predetermined potential by the charger 13 is exposed by the LPH 14 that emits light based on the image data obtained from the image processing unit 40. Thus, an electrostatic latent image is formed on the photosensitive drum 12. The formed electrostatic latent image is developed by the developing device 15, and a yellow (Y) toner image is formed on the photosensitive drum 12. Similarly, magenta (M), cyan (C), and black (K) toner images are also formed in the image forming units 11M, 11C, and 11K.

Each color toner image formed by each image forming unit 11 is sequentially electrostatically attracted by the primary transfer roll 22 onto the intermediate transfer belt 21 rotating in the direction of the arrow in FIG. A toner image is formed. The superimposed toner image is conveyed to a region (secondary transfer portion) where the secondary transfer roll 23 is disposed as the intermediate transfer belt 21 moves. When the superimposed toner image is conveyed to the secondary transfer unit, the paper P is supplied to the secondary transfer unit in accordance with the timing at which the toner image is conveyed to the secondary transfer unit. Then, the superimposed toner images are collectively electrostatically transferred onto the conveyed paper P by the transfer electric field formed by the secondary transfer roll 23 in the secondary transfer portion.
Thereafter, the sheet P on which the superimposed toner image has been electrostatically transferred is peeled off from the intermediate transfer belt 21 and conveyed to the fixing device 25 by the conveying belt 24. The unfixed toner image on the paper P conveyed to the fixing device 25 is fixed on the paper P by being subjected to fixing processing by heat and pressure by the fixing device 25. Then, the paper P on which the fixed image is formed is conveyed to a paper discharge mounting portion (not shown) provided in the discharge portion of the image forming apparatus 1.

FIG. 2 is a diagram showing a configuration of an LED print head (LPH) 14 that is an exposure apparatus.
As shown in FIG. 2, the LPH 14 is a signal generation circuit that drives a housing 61 as a support, a self-scanning LED array (SLED) 63 that constitutes a light emitting section as an example of a light emitting element array member, and SLED 63 and SLED 63. An LED circuit board 62 on which a signal generation circuit 100 (see FIG. 3 to be described later) as an example is mounted, a rod lens array 64 that is an optical member that forms an image of light from the SLED 63 on the surface of the photosensitive drum 12, and a rod lens array 64. A holder 65 that shields the SLED 63 from the outside and a leaf spring 66 that pressurizes the housing 61 in the direction of the rod lens array 64 are provided.

The housing 61 is formed of a block or sheet metal such as aluminum or SUS, and supports the LED circuit board 62. The holder 65 supports the housing 61 and the rod lens array 64, and is set so that the light emitting point of the SLED 63 and the focal point of the rod lens array 64 coincide. Furthermore, the holder 65 is configured to seal the SLED 63. This prevents dust from adhering to the SLED 63 from the outside. On the other hand, the leaf spring 66 presses the LED circuit board 62 in the direction of the rod lens array 64 through the housing 61 so as to maintain the positional relationship between the SLED 63 and the rod lens array 64.
The LPH 14 configured in this manner is configured to be movable in the optical axis direction of the rod lens array 64 by an adjustment screw (not shown), and the imaging position (focal plane) of the rod lens array 64 is the surface of the photosensitive drum 12. It is adjusted so that it is located above.

FIG. 3 is a plan view of the LED circuit board 62.
On the LED circuit board 62, as shown in FIG. 3, an SLED 63 as an example of a light emitting element array member made up of, for example, 58 SLED chips (CHIP1 to CHIP58) is parallel to the axial direction of the photosensitive drum 12. Are arranged in a line with high accuracy. In this case, each LED array is arranged continuously at the connection portion between the SLED chips at the end boundary of the arrangement (LED array) of the light emitting elements (LEDs) arranged in each SLED chip (CHIP1 to CHIP58). In addition, the SLED chips are alternately arranged in a staggered pattern.
The LED circuit board 62 stores a signal generation circuit 100 that generates a signal (lighting signal) for driving the SLED 63, a level shift circuit 104, a three-terminal regulator 101 that outputs a predetermined voltage, a light amount correction coefficient of the SLED 63, and the like. A harness 103 is provided for transmitting and receiving signals to and from the EEPROM 102, the control unit 30, and the image processing unit 40 (both see FIG. 1).

Next, the SLED 63 provided on the LED circuit board 62 will be described.
FIG. 4 is a diagram for explaining an example of the circuit configuration of the SLED 63.
The SLED 63 shown in FIG. 4 shows an SLED chip for resolution (light emitting element arrangement density) 600 dpi (dot per inch) as an example, and 128 light emitting elements (LEDs) are arranged per SLED chip.

The SLED 63 of this embodiment is connected to the signal generation circuit 100 via the level shift circuit 104. The level shift circuit 104 has a configuration in which a resistor R1B and a capacitor C1, and a resistor R2B and a capacitor C2 are arranged in parallel, one end of which is connected to the input terminal of the SLED 63, and the other end of the signal generation circuit 100. Connected to the output terminal. The transfer signal CK1 and the transfer signal CK2 are output to the SLED 63 based on the transfer signals CK1R and CK1C and the transfer signals CK2R and CK2C output from the signal generation circuit 100.
In the SLED 63 of the present embodiment, 58 SLED chips are arranged in series, but FIG. 4 shows only one SLED chip and a signal line connected thereto. In the following description, the SLED chip is referred to as SLED 63 for convenience.

The SLED 63 shown in FIG. 4 includes 128 thyristors S1 to S128, 128 LEDs L1 to L128, 128 diodes D1 to D128, 128 resistors R1 to R128, and excessive current in the signal lines Φ1 and Φ2. The transfer current limiting resistors R1A and R2A are configured to prevent the current from flowing.
In the SLED 63 shown in FIG. 4, the anode terminals (input terminals) A <b> 1 to A <b> 128 of the thyristors S <b> 1 to S <b> 128 are connected to the power supply line 105. The power supply line 105 is supplied with the output voltage VDD (VDD = + 3.3 V) of the three-terminal regulator 101.

.., S127 are supplied with the transfer signal CK1 from the signal generation circuit 100 and the level shift circuit 104 via the transfer current limiting resistor R1A. The cathode terminals (output terminals) K1, K3,. Sent.
In addition, the transfer signal CK2 from the signal generation circuit 100 and the level shift circuit 104 is transferred to the transfer current limiting resistor R2A at the cathode terminals (output terminals) K2, K4,... K128 of the even-numbered thyristors S2, S4,. Sent through.

On the other hand, gate terminals (control terminals) G1 to G128 of the thyristors S1 to S128 are respectively connected to the power supply line 106 via resistors R1 to R128 provided corresponding to the thyristors S1 to S128. The power supply line 106 is grounded (GND).
The gate terminals G1 to G128 of the thyristors S1 to S128 are connected to the gate terminals of the LEDs L1 to L128 provided corresponding to the thyristors S1 to S128, respectively.

Furthermore, the cathode terminals of the diodes D1 to D128 are connected to the gate terminals G1 to G128 of the thyristors S1 to S128. The gate terminals G1 to G127 of the thyristors S1 to S127 are connected to the anode terminals of the next-stage diodes D2 to D128, respectively. That is, the diodes D1 to D128 are connected in series with the gate terminals G1 to G127 interposed therebetween.
The anode terminal of the diode D1 is connected to the signal generation circuit 100 via the transfer current limiting resistor R2A and the level shift circuit 104, and the transfer signal CK2 is transmitted. Further, the cathode terminals of the LEDs L1 to L128 are connected to the signal generation circuit 100, and the lighting signal ΦI is transmitted.
Further, a light shielding mask 50 is disposed on the SLED 63 so as to cover the thyristors S1 to S128 and the diodes D1 to D128. During the image forming operation, light emission from the thyristors S1 to S128 in the on state and the current is flowing, and the diodes D1 to D128 in the state of the current flowing are blocked, and unnecessary light passes through the photosensitive drum 12. It is provided in order to suppress exposure.

<Control of current value>
Subsequently, the signal generation circuit 100 provided on the LED circuit board 62 will be described.
FIG. 5 is a block diagram illustrating a configuration of the signal generation circuit 100 included in the image forming apparatus 1.
The signal generation circuit 100 converts the image data acquired from the image processing unit 40 into a format suitable for light emission of the SLED 63 and outputs the converted image data, and the image data acquired from the image processing unit 40. A density determination unit 111 is provided as an example of a determination unit that divides a block into a predetermined size and determines the density (gradation degree) of the block. Moreover, it has the light quantity correction coefficient calculation circuit 112 by lighting rate as an example of the light emission quantity correction | amendment means which outputs the light quantity correction coefficient according to lighting rate. The lighting rate-specific light amount correction coefficient is a coefficient for correcting a current value of a lighting signal output from a pulse generation circuit 115 described later based on a determination result of the density determination unit 111.

  In addition, the signal generation circuit 100 includes a light amount variation correction coefficient storage unit 113 as an example of a storage unit that stores a variation correction coefficient for correcting variations in the amount of light of the LEDs L1 to L128 in the SLED 63. Further, the lighting signal current value is calculated using the lighting rate-specific light amount correction coefficient output by the lighting rate-specific light amount correction coefficient calculation circuit 112 and the variation correction coefficient stored in the light amount variation correction coefficient storage unit 113. A current value calculation circuit 114 as an example of a lighting signal calculation means for outputting to the pulse generation circuit 115. Furthermore, a pulse generation circuit 115 as an example of a lighting signal output unit that generates a lighting signal corresponding to the converted image data output from the image data rearrangement circuit 110 and outputs it to the SLED 63 is provided.

The image data rearrangement circuit 110 converts the image data acquired from the image processing unit 40 into a format suitable for the light emission of the SLED 63 and outputs the converted image data. Specifically, the image data rearrangement circuit 110 converts the serial format image data acquired from the image processing unit 40 into, for example, a first pixel to a 128th pixel, a 129th pixel to a 256th pixel,. As in the 7424th pixel, etc., processing such as dividing into image data to be transmitted for each SLED chip (CHIP1 to CHIP58) and converting into parallel signals (serial / parallel conversion) is performed. Then, the image data rearrangement circuit 110 outputs the divided image data to the pulse generation circuit 115.
The density determination unit 111 determines the density (gradation level) of a block having a predetermined size included in the image data acquired from the image processing unit 40.

The lighting rate-specific light amount correction coefficient calculation circuit 112 outputs a lighting rate-specific light amount correction coefficient as an example of a correction coefficient for correcting the current of the lighting signal output from the pulse generation circuit 115 based on the determination result of the density determination unit 111. . Specifically, the light amount correction coefficient for each lighting rate based on the gradation determined for each block described later is output to the current value calculation circuit 114 as the light amount correction coefficient for each pixel of the image data.
The light amount variation correction coefficient storage unit 113 stores a variation correction coefficient for correcting the variation in the light amount of each LED in the SLED 63. The variation correction coefficient is data set for each of the LEDs L1 to L128, and corresponds to, for example, the ratio of the light amount of each LED to the reference light amount of the LED. The variation correction coefficient is output to the current value calculation circuit 114 as 8-bit (0 to 255) data, for example.

The current value calculation circuit 114 is a variation correction for each of the LEDs L <b> 1 to L <b> 128 stored in the light amount variation correction coefficient storage unit 113 and the light amount variation correction coefficient storage unit 113 for each pixel output by the light rate correction coefficient calculation circuit 112. Using the coefficient, a current value suitable for the lighting signal is calculated for each pixel and output to the pulse generation circuit 115. In order to simplify the circuit, the current value calculation circuit 114 outputs, for example, a product obtained by multiplying the light amount correction coefficient for each lighting rate and the variation correction coefficient to the pulse generation circuit 115.
The pulse generation circuit 115 generates a lighting signal corresponding to the converted image data output from the image data rearrangement circuit 110 and outputs it to the SLED 63. Specifically, the pulse generation circuit 115 converts the product of the light amount correction coefficient for each lighting rate and the variation correction coefficient for each pixel output from the current value calculation circuit 114 and the converted image output from the image data rearrangement circuit 110. Based on the data, a lighting signal for each of the LEDs L1 to L128 is generated and output to the SLED 63.
Note that the pulse generation circuit 115 may be configured to fix the current value of the lighting signal to be output and output the lighting signal by varying the pulse width according to the input. Specifically, for example, the converted image output from the image data rearrangement circuit 110 based on the product output by the lighting signal calculation means (not shown) multiplied by the lighting rate-specific light amount correction coefficient and the variation correction coefficient. The data is pulse-modulated (PWM) by the pulse generation circuit 115, and the pulse width of the lighting signal is varied and output.

A lighting signal generation process performed in the signal generation circuit 100 having the above configuration will be described.
FIG. 6 is a flowchart showing a lighting signal generation process.
The image data transmitted from the image processing unit 40 of the image forming apparatus 1 is simultaneously received by the image data rearrangement circuit 110 and the density determination unit 111 in the signal generation circuit 100 (step 101).
The density determination unit 111 that has received the image data divides the received image data into blocks of a predetermined size (step 102), and determines the density (gradation degree) of the block. Specifically, the number of light emitting pixels included in the block obtained by division is counted (step 103), and divided by the number of pixels in the entire block to calculate the density (gradation degree) of the block.

(Counting the number of light emitting pixels in the block)
FIG. 7 is a diagram for explaining the number of light emitting pixels in a divided block.
In step 102, the density determination unit 111 divides the acquired image data into blocks having a predetermined size (for example, a size of 5 pixels vertically and 5 pixels horizontally). The block size at this time is determined in advance by the processing capability of the CPU of the density determination unit 111 that performs processing and the light amount correction coefficient calculation circuit 112 for each lighting rate.
Thereafter, in step 103, for example, as shown in FIG. 7, when the block A has one light emitting pixel and the block B has three, the density (gradation degree) of the block A is 1/25 = 4%, In block B, 3/25 = 12%. As described above, the gradation is determined for each block.

The block size is determined in advance, and the value obtained by dividing the counted number of light-emitting pixels by the total number of pixels in the block is proportional to the number of light-emitting pixels. Therefore, to simplify the circuit, the number of counted light-emitting pixels is The block density may be output to the lighting rate-specific light amount correction coefficient calculation circuit 112. Also in this embodiment, the number of light emitting pixels is used for information transmission.
Moreover, although the case where the acquired image data is divided into predetermined blocks has been described as an example, the present application is not limited to this. For example, the number of light emitting pixels may be counted in a block including peripheral pixels centered on the target pixel.

Returning to FIG. 6, the description will be continued.
After acquiring the number of light emitting pixels in step 103, the lighting rate-specific light amount correction coefficient calculation circuit 112 determines whether or not the acquired number of light emitting pixels is smaller than a predetermined threshold (step 104).
When the number of light emitting pixels is smaller than a predetermined threshold (step 104: Y), it is determined that the block has a low gradation. Then, the lighting rate-specific light amount correction coefficient calculation circuit 112 outputs a light rate correction factor-specific light amount correction coefficient determined for each block in association with each pixel in order to increase the light emission amount of the SLED 63 that displays the light-emitting pixel (step). 105).

On the other hand, when the number of light emitting pixels is larger than the predetermined threshold (step 104: N), the lighting rate-specific light amount correction coefficient calculation circuit 112 outputs “1” as the lighting rate-specific light amount correction coefficient (step 108). The process proceeds to step 106.
In this step 106, in parallel with the count processing of the number of light emitting pixels in the density determination unit 111 and the lighting rate-specific light amount correction coefficient calculation circuit 112, the light amount variation correction coefficient storage unit 113 stores each LED in the stored SLED 63. A variation correction coefficient for each of the LEDs L <b> 1 to L <b> 128 for correcting variation in the amount of light is output to the current value calculation circuit 114.

In the current value calculation circuit 114, when the light amount correction coefficient for each lighting rate of each pixel is acquired from the light amount correction coefficient calculation circuit 112 for each lighting rate, the acquired light amount correction coefficient for each lighting rate and the light amount variation correction coefficient storage unit 113 are acquired. Is multiplied by the variation correction coefficient for each of the LEDs L1 to L128, and the product is output for each of the LEDs L1 to L128 (step 107).
On the other hand, when the light amount correction coefficient by lighting rate is not acquired from the light amount correction coefficient calculation circuit 112 by lighting rate, the current value for each of the LEDs L1 to L128 is based on the variation correction coefficient acquired from the light amount variation correction coefficient storage unit 113. Is calculated.

On the other hand, in parallel with the lighting signal calculation processing (steps 102 to 107), the image data rearrangement circuit 110 rearranges the image data acquired in step 101 by serial / parallel conversion, and converts the converted image data. (Step 110).
Then, the pulse generation circuit 115 generates a lighting signal for each of the LEDs L1 to L128 based on the product output from the current value calculation circuit 114 and the converted image data output from the image data rearrangement circuit 110. Are output to the SLED 63 (step 115).
Through the above steps, the SLED 63 is turned on in response to the output lighting signal.

<Relationship between light emitting pixel density (gradation level) and light emission amount>
Next, the relationship between the density (gradation level) of the light emitting pixel and the light emission amount will be described.
An isolated pixel (isolated pixel) and a non-isolated pixel (non-isolated pixel) may differ in the light emission amount of the light emitting element (the light emission amount with respect to the photosensitive drum) when receiving a lighting signal having the same intensity. It was found by experiment.

FIG. 8 is a diagram for explaining a difference in light emission amounts of light emitting elements that have received a lighting signal having the same intensity for isolated pixels and non-isolated pixels. The vertical axis indicates the ratio of the light emission amounts, and the horizontal axis indicates the pixel position. The horizontal line in the graph is a specification of the light emission amount required for the light emitting element. Here, the “specification” is the intensity of the light emission amount of the light emitting element that is necessary for charging the surface of the photoreceptor exposed to the light emitting element to a predetermined potential and holding the toner.
FIG. 8A shows the amount of light emitted from the light emitting element when one isolated pixel (hereinafter referred to as an isolated pixel) is turned on, and FIG. 8B shows two adjacent pixels (hereinafter referred to as adjacent pixels). .) Shows the light emission amount when 16 consecutive pixels (hereinafter referred to as continuous pixels) are turned on.
The solid line in the figure indicates the amount of light emitted when a normal (100%) current lighting signal is applied, and the dotted line (dotted) indicates a current lighting signal that is 20% higher than the normal current. The amount of emitted light and the broken line (dashed) indicate the amount of emitted light when a lighting signal with a current increased by 30% is applied.

As can be seen from the solid line in FIG. 8, when the applied current is 100%, the maximum light emission amount in the order of the isolated pixel in FIG. 8A, the adjacent pixel in FIG. 8B, and the continuous pixel in FIG. It turns out that becomes large. Further, it can be seen that in the isolated pixel in FIG. 8A and the adjacent pixel in FIG.
Therefore, the change in the maximum light emission amount was examined by changing the current applied to the light emitting element depending on the state of the light emitting pixel (the state of the pixel interval).

In the case of the isolated pixel shown in FIG. 8A, the light emission amount reaches the specification when the current value of the lighting signal is increased to 30% with respect to the current state (indicated by a broken line as 130%). In the adjacent pixel shown in FIG. 8B, the light emission amount satisfies the specification when the current value of the lighting signal is increased by 20% (indicated by a dotted line as 120%). The continuous pixel shown in FIG. 8C satisfies the specification even when the current value (shown by a solid line as 100%) is the current value.
Based on the above experimental results, in the present embodiment, the current value of the lighting signal applied to the light emitting element is changed in accordance with the density (gradation degree) of the light emitting pixel.

Next, the relationship between the density D _{out of the} pixels output at various densities (gradation levels) C _in of the light emitting pixels was examined.
FIG. 9 is a diagram illustrating the relationship between the lighting rate and the output pixel density _Dout . The horizontal axis indicates the lighting rate (%), and the vertical axis indicates the measurement result of the output pixel density D _out (%).
Normally, the density when the lighting rate is 100% is about 1.2 with respect to the “specification” described in FIG. 8, but the graph shown here is based on the density when the lighting rate is 100%. It is expressed as a percentage (%). FIG. 9A shows the relationship in the entire lighting rate of 0 to 100%, and FIG. 9B shows the relationship with the density in a particularly low range of the lighting rate (lighting rate of 0 to 10%). . Moreover, in any figure, the measurement result in the state before applying this embodiment (before current value correction) is shown by a broken line, and the measurement result in the state after application (after current value correction) is shown by a solid line. .

As shown in FIG. 9A, before the current value correction (broken line), the pixel density _Dout output in the region where the lighting rate is 10% or less is lower than the original density (ideal line). I understand. That is, in the region where the lighting rate is low, the density of the output pixel does not satisfy the specification. As can be seen from the light emission amount change before (dashed line), the range of concentration D _out has not reached the original concentration (ideal line), the lighting rate is less area to about 40%.
In response to this, the current value applied to the light emitting element was manipulated in a region where the lighting rate was about 40% or less. It can be seen that the density of the pixel after changing the light emission amount (solid line) is improved as compared with the density of the pixel in the conventional case where the current value is not manipulated (broken line), and has reached the original light emission amount. As shown in FIG. 9B, the density is improved in the lighting rate range of 0 to 10%.

We investigated the optimum value of the current to be applied to the light-emitting pixel in a concentration (gradation degree) C _in the light-emitting pixels.
Figure 10 is a diagram showing the relation between the current value applied to the light emitting pixels and gradation degree C _in. The horizontal axis represents the gradation C _in (%) of the pixel to be lit, and the vertical axis represents the current (%) applied to the light emitting pixel.
In FIG. 8C described above, in the case of continuous pixels, it was found that the light emission amount of all the pixels satisfied the specification at a current value of 100%. In FIG. 8A, it was found that the light emission amount of the isolated pixel satisfies the specification when the current value is 130%.

Therefore, as shown in FIG. 10, in the high gradation region (region where the gradation degree is larger than H _Cin ), the current value of the lighting signal applied to the light emitting pixel is set to 100% as usual. If gradation degree C _in a low, since the pixel to be output wider pixel interval does not exist in the next, and increases the current value of the lighting signal. Based on the result of FIG. 8A, the upper limit was set to 130%.
As a result of intensive studies by the inventors, for example, gradation degree C _in the In about 5% or less, experiments that be output further increasing the current value output pixel hardly visible results. In response to such an experimental result, in the present embodiment, as shown in FIG. 10, the current value is saturated to 130% near the lower limit (region where the gradation is smaller than L _Cin ), and a saturated region is formed near the lower limit. I made it. This is a countermeasure against the low degree of improvement in density in the region of 5% or less in FIG.

(Handling white)
Next, a case where a low gradation pixel is included in a block with many high gradation pixels will be described below.
FIGS. 11A and 11B are diagrams for explaining the handling in the case of white. FIG. 11A shows an output example for explaining the handling in the case of white, and FIG. 11B shows the relationship between the ratio of the output current and the light emission amount at the measurement position in FIG. 11A. ing.
As can be seen from FIG. 8C described above, the endmost pixel of the continuous high gradation pixels tends to have a smaller light emission amount than the other pixels (second and subsequent pixels). That is, the light emission amount of the high gradation pixel in contact with the low gradation pixel is low. As a result, the boundary was unclear.

For example, the description will be made based on the gradation Cin when the output is as shown _in FIG.
When 100% current was applied to the high gradation pixel (pixel A) in contact with the low gradation pixel and output, the gradation C _{in the} vicinity of the boundary between the pixel A and the low gradation pixel was 70%. . On the other hand, the gradation C _in of the pixel B when the current of 100% was applied and output was 100% (see the solid line in FIG. 11B).
In accordance with the graph shown in FIG. 10, a current value of 107% at a gradation degree C _{in of} 70% is applied, and the light emission amount at the measurement position shown in FIG. 11A is indicated by a broken line in FIG. It can be seen that the gradation of the pixel (pixel A) adjacent to the low gradation pixel is high and satisfies the specifications. As a result, the boundary between the high gradation pixel and the low gradation pixel became clear. As a result, for example, when white characters are output on a black background, white portions can be clearly output.

<Pulse width control>
In the signal generation circuit 100, the current value of the lighting signal is controlled based on the gradation. However, it is also possible to ensure the reproducibility of the low gradation image by controlling the light emission time of the light emitting element. For example, in the signal generation circuit 100 shown in FIG. 5, the current value calculation circuit 114 can be replaced with a pulse width calculation circuit as an example of a lighting signal calculation unit that calculates the pulse width of the lighting signal based on the degree of gradation. .

<Control of current value and pulse width>
Since the current of the lighting signal and the pulse width can be controlled independently of each other, the current value of the lighting signal is controlled based on the gradation, and the pulse based on the variation in the amount of light emission between the plurality of light emitting elements. A signal generation circuit 200 as another example of the signal generation circuit for controlling the width will be described.
FIG. 12 is a block diagram illustrating a configuration of the signal generation circuit 200 included in the image forming apparatus 1. Instead of the signal generation circuit 100 shown in FIG. 5, a current value calculation circuit 211 and a pulse width calculation circuit 212 are provided. The same functions as those in FIG. 5 are denoted by the same reference numerals, and detailed description thereof is omitted here.
The current value calculation circuit 211 calculates a current value suitable for the lighting signal based on the lighting rate-specific light amount correction coefficient output from the lighting rate-specific light amount correction coefficient calculation circuit 112, and outputs the calculated current value to the pulse generation circuit 115. Yes. It functions as an example of a lighting signal calculation means or a current value calculation circuit in the present embodiment. The pulse width calculation circuit 212 calculates a pulse width suitable for the lighting signal based on the variation correction coefficient stored in the light amount variation correction coefficient storage unit 113 and outputs the pulse width to the pulse generation circuit 115. It functions as an example of a lighting signal calculation means or a pulse width calculation circuit in this embodiment.

Data processing of image data performed in the signal generation circuit 200 having the above configuration will be described.
FIG. 13 is a flowchart showing data processing of image data.
The image data transmitted from the image processing unit 40 of the image forming apparatus 1 is simultaneously received by the image data rearrangement circuit 110 and the density determination unit 111 in the signal generation circuit 200 (step 501).

  The density determination unit 111 that has received the image data divides the image data into blocks of a predetermined size (step 502), and counts the number of light-emitting pixels included in the block (step 503). The counted number of light emitting pixels is output to the lighting rate-specific light amount correction coefficient calculation circuit 112.

The lighting rate-specific light amount correction coefficient calculation circuit 112 that has acquired the number of light emitting pixels determines whether or not the number of light emitting pixels is smaller than a predetermined threshold (step 504).
When the number of light emitting pixels is smaller than the predetermined threshold (step 504: Y), it is determined that the block has a low gradation. Then, the lighting rate-specific light amount correction coefficient calculation circuit 112 outputs the lighting rate-specific light amount correction coefficient to the current value calculation circuit 211 in order to increase the light amount of the SLED 63 that displays the light emitting pixel (step 505).

On the other hand, when the number of light-emitting pixels is larger than the predetermined threshold (step 504: N), the lighting rate-specific light amount correction coefficient calculation circuit 112 outputs “1” as the lighting rate-specific light amount correction coefficient (step 509). The processing moves to step 506.
The current value calculation circuit 211 calculates a current value suitable for the lighting signal based on the lighting rate-specific light amount correction coefficient acquired from the lighting rate-specific light amount correction coefficient calculation circuit 112, and outputs the calculated current value to the pulse generation circuit 115 (step). 506). When the light quantity correction coefficient for each lighting rate is not acquired from the light quantity correction coefficient calculation circuit 112 for each lighting rate, that is, when the number of light emitting pixels in the block is larger than a predetermined threshold and has a high gradation, the current value calculation circuit 211 emits light for the light emitting pixels. The power value corresponding to the original light emission amount of the lighting signal is output without correcting the amount.

In parallel with the counting process of the number of light emitting pixels in the density determination unit 111 and the lighting rate-specific light amount correction coefficient calculation circuit 112, the light amount variation correction coefficient storage unit 113 corrects the variation in the light amount of each LED in the stored SLED 63. The variation correction coefficient for performing this is output to the pulse width calculation circuit 212 (step 507).
The pulse width calculation circuit 212 calculates a pulse width suitable for the lighting signal based on the variation correction coefficient acquired from the light amount variation correction coefficient storage unit 113 and outputs it to the pulse generation circuit 115 (step 508).

On the other hand, in parallel with the calculation processing of the lighting signal (steps 502 to 508), the image data rearrangement circuit 110 rearranges the image data acquired in step 501 by serial / parallel conversion, and converts the converted image data. Is output (step 510).
Based on the current value output from the current value calculation circuit 211 and the pulse width output from the pulse width calculation circuit 212 in the pulse generation circuit 115 that acquired the converted image data output from the image data rearrangement circuit 110. Thus, a lighting signal is generated and output (step 515).
In response to the lighting signal output from the pulse generation circuit 115 through the above steps, the SLED 63 is lit.

  In the above-described embodiment, the current value calculation circuit 211 calculates the current value of the lighting signal based on the lighting rate-specific light amount correction coefficient output from the lighting rate-specific light amount correction coefficient calculation circuit 112, and the light amount variation correction coefficient storage unit 113. Although the pulse width of the lighting signal is calculated by the pulse width calculation circuit 212 based on the variation correction coefficient acquired from the above, the present invention is not limited to this. The pulse width of the lighting signal may be calculated based on the light amount correction coefficient for each lighting rate, and the current value of the lighting signal may be calculated based on the variation correction coefficient. This is because the current value of the lighting signal and the number of times of light emission can be controlled independently of each other.

  Programs corresponding to the flowcharts shown in FIGS. 6 and 13 are recorded on an information recording medium such as a flexible disk or a hard disk, or these programs are distributed and recorded via a network such as the Internet. Can be read and executed by a general-purpose computer or the like included in the image forming apparatus 1 or the like, for example, so that the computer or the like can function as a part of the image forming apparatus 1 or the like.

1 is a diagram illustrating an overall configuration of an image forming apparatus in which an LED print head according to an embodiment is used. It is the figure which showed the structure of the LED print head (LPH). It is a top view of a LED circuit board. It is a figure explaining an example of the circuit structure of SLED. 1 is a block diagram illustrating a configuration of a signal generation circuit included in an image forming apparatus. It is a flowchart which shows the production | generation process of a lighting signal. It is a figure for demonstrating the number of the light emission pixels in the divided | segmented block. It is a figure explaining the difference in the light emission amount of the light emitting element which received the lighting signal of the same intensity about an isolated pixel and a non-isolated pixel. It is a figure which shows the relationship between a gradation degree and the density | concentration of the output pixel. It is a figure which shows the relationship between a gradation degree and the electric current value of the lighting signal applied to a light emitting element. It is a figure for demonstrating the handling in the case of white. 1 is a block diagram illustrating a configuration of a signal generation circuit included in an image forming apparatus. It is a flowchart which shows the data processing of image data.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 10 ... Image forming process part (image forming part), 12 ... Photosensitive drum (image holding body), 14 ... LED print head (LPH) (exposure device), 40 ... Image processing part (image processing) Means), 63 ... Self-scanning LED array (SLED) (light emitting element array member), 100, 200 ... Signal generation circuit, 110 ... Image data rearrangement circuit (data conversion means), 111 ... Density determination unit (determination means) , 112 ... Light amount correction coefficient calculation circuit for each lighting rate (light emission amount correction means), 113 ... Light quantity variation correction coefficient storage section (storage means), 114 ... Current value calculation circuit (lighting signal calculation means), 115 ... Pulse generation circuit ( Lighting signal output means), 211... Current value calculation circuit (current value calculation circuit, lighting signal calculation means), 212... Pulse width calculation circuit (pulse width calculation circuit, lighting signal calculation means)

Claims (9)

Determination means for determining the density of a predetermined region composed of a plurality of pixels including the light emitting pixels of the acquired image data;
Based on the density of the predetermined area determined by the determining means, it is determined whether the image data of the predetermined area includes a thin line or an isolated pixel, and it is determined that the image data includes a thin line or an isolated pixel. A light emission amount correcting means for outputting a correction coefficient for correcting the light emission amount of the light emitting element array member corresponding to the light emitting pixel among the plurality of light emitting element array members in which the plurality of light emitting elements are arranged;
A signal generation circuit comprising: a lighting signal output unit that generates a lighting signal having a light emission amount corrected based on the correction coefficient output by the light emission amount correction unit and outputs the lighting signal to the light emitting element array member. .   The light emission amount correction means is determined by the determination means in comparison with a predetermined threshold relating to density used when determining whether or not the image data of the predetermined area includes a thin line or an isolated pixel. When the density of the predetermined region is small, a correction coefficient for correcting the light emission amount of the light emitting element array member corresponding to the light emitting pixel in the predetermined region to a value larger than the original light emission amount of the light emitting pixel is output. The signal generation circuit according to claim 1.   The signal generation circuit according to claim 1, wherein the determination unit determines the density of the predetermined region based on the number of the light emitting pixels in the predetermined region. Storage means for storing a variation correction coefficient for correcting variation in the amount of light of each of the plurality of light emitting element array members;
Based on the correction coefficient output by the light emission amount correction means and the variation correction coefficient stored in the storage means, the current value and pulse width of the lighting signal of the light emitting element array member corresponding to the light emitting pixel The signal generation circuit according to claim 1, further comprising: a lighting signal calculation unit that calculates and outputs either of them. A plurality of light emitting element array members in which a plurality of light emitting elements are arranged;
Including a signal generation circuit,
The signal generation circuit includes:
Determination means for determining the density of the predetermined region based on the number of light emitting pixels in the predetermined region including a plurality of pixels including the light emitting pixels of the acquired image data;
The density of the predetermined area determined by the determination means is compared with a predetermined threshold relating to the density used when determining whether the image data of the predetermined area includes a thin line or an isolated pixel. A light emission amount correction that outputs a correction coefficient for correcting the light emission amount of the light emitting element array member corresponding to the light emission pixel in the predetermined region to a value larger than the original light emission amount of the light emission pixel when smaller than a predetermined threshold value Means,
Storage means for storing a variation correction coefficient for correcting variation in the amount of light of each of the plurality of light emitting element array members;
Based on the correction coefficient output from the light emission amount correcting means and the variation correction coefficient stored in the storage means, the current value and the number of times of light emission of the lighting signal to the light emitting element array member corresponding to the light emitting pixel Lighting signal calculation means for calculating and outputting any of
An exposure apparatus comprising: a lighting signal output unit that generates a lighting signal of a light emission amount based on an output of the lighting signal calculation unit and outputs the signal to the light emitting element array member. The lighting signal calculation means includes
The current of the lighting signal to the light emitting element array member corresponding to the light emitting pixel based on one of the correction coefficient output by the light emission amount correcting means and the variation correction coefficient stored in the storage means A current value calculation circuit for calculating and outputting a value;
The exposure apparatus according to claim 5, further comprising: a pulse width calculation circuit that calculates and outputs a pulse width of the lighting signal based on the other of the correction coefficient and the variation correction coefficient.   When the density of the predetermined region is greater than a predetermined value, the light emission amount correcting unit causes the light emission amount of the light emitting element array member corresponding to the light emitting pixel in the predetermined region to be greater than the original light emission amount of the light emitting pixel. 6. The exposure apparatus according to claim 5, wherein a correction coefficient for correcting to a small value is output. An image carrier,
Image processing means for performing predetermined image processing on image information acquired from the outside and outputting as image data;
A plurality of light emitting elements arrayed, and a plurality of light emitting element array members for irradiating the image carrier with light;
Determination means for determining the density of the predetermined area based on the number of light emitting pixels in the predetermined area including a plurality of pixels including the light emitting pixels of the image data acquired from the image processing means;
The density of the predetermined area determined by the determination means is compared with a predetermined threshold relating to the density used when determining whether the image data of the predetermined area includes a thin line or an isolated pixel. A light emission amount correction that outputs a correction coefficient for correcting the light emission amount of the light emitting element array member corresponding to the light emission pixel in the predetermined region to a value larger than the original light emission amount of the light emission pixel when smaller than a predetermined threshold value Means,
Storage means for storing a variation correction coefficient for correcting variation in the amount of light of each of the plurality of light emitting element array members;
Based on the correction coefficient output from the light emission amount correcting means and the variation correction coefficient stored in the storage means, the current value and the number of times of light emission of the lighting signal to the light emitting element array member corresponding to the light emitting pixel Lighting signal calculation means for calculating and outputting any of
A lighting signal output unit that generates a lighting signal corresponding to the image data acquired from the image processing unit based on an output of the lighting signal calculation unit and outputs the lighting signal to the plurality of light emitting element array members. Image forming apparatus. On the computer,
A determination function for determining the density of the predetermined region based on the number of light emitting pixels in the predetermined region including a plurality of pixels including the light emitting pixels of the acquired image data;
The determined density of the predetermined area is smaller than the predetermined threshold compared to a predetermined threshold relating to the density used when determining whether the image data of the predetermined area includes a thin line or an isolated pixel. A light emission amount correction function for outputting a correction coefficient for correcting the light emission amount of the light emitting element array member corresponding to the light emission pixel in the predetermined region to a value larger than the original light emission amount of the light emission pixel;
Based on the correction coefficient and the variation correction coefficient stored in the storage means for storing the variation correction coefficient for correcting the variation in the amount of light of each of the plurality of light emitting element array members in which the plurality of light emitting elements are arranged, The program which implement | achieves the lighting signal calculation function which calculates and outputs either the electric current value of the lighting signal of the said light emitting element array member corresponding to a light emission pixel, and the frequency | count of light emission.

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