JP2008268812A - Image forming apparatus and control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the frequency of adjusting various setup conditions for an exposure device. <P>SOLUTION: An integrated value relating to the length of time that light is emitted from LEDs arranged in an SLED 63 is calculated by an integrating section 120. Based on the integrated value calculated by the integrating section 120, a determination is made whether exposure conditions set by an LED print head (LPH) is adjusted or not. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and a control apparatus.

For example, an exposure apparatus mounted on an image forming apparatus using an electrophotographic system is known which uses a light emitting element array in which light emitting elements such as LEDs are arranged in a line.
With regard to such an exposure apparatus, for example, in Patent Document 1, the amount of light emitted from each light emitting element arranged in the exposure apparatus is measured, and the light quantity correction for each light emitting element is performed based on the measured light quantity distribution of each light emitting element. A technique is described in which a value is obtained and the light amount of each light emitting element is corrected based on the obtained light amount correction value.
Japanese Patent Application Laid-Open No. 2004-228561 describes a technique for correcting the deviation when each light emitting element arranged in the exposure apparatus is displaced from a predetermined reference position.

JP 2002-127492 A JP-A-4-291372

  An object of the present invention is to reduce the frequency of adjustment of various setting conditions performed on an exposure apparatus.

  According to the first aspect of the present invention, an image holding body and a plurality of light emitting elements that are turned on based on image data are arranged, an exposure unit that exposes the image holding body, and the plurality of light emitting elements arranged in the exposure unit Calculating means for calculating an integrated value related to the light emission time, and determining means for determining whether or not to adjust the exposure condition set by the exposure means based on the integrated value calculated by the calculating means And an image forming apparatus.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, a light emission time setting unit that sets a light emission time per lighting of each of the plurality of light emitting elements arranged in the exposure unit; Measuring means for measuring the number of image data for setting each of the light emitting elements to a lighting state, and the calculating means includes the light emission time set by the light emission time setting means and the measurement means. The integrated value is calculated based on the number of image data to be measured.
According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, the determination unit performs the determination every predetermined time.
According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, the determination unit sets the predetermined time that varies depending on the type of the exposure condition.

According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect, the determination unit determines to adjust the exposure condition when the integrated value reaches a predetermined value or more. Features.
According to a sixth aspect of the present invention, in the image forming apparatus according to the first aspect, the determination unit calculates power consumption in the plurality of light emitting elements from the integrated value, and whether the power consumption exceeds a predetermined value. The determination is performed based on whether or not.
According to a seventh aspect of the present invention, in the image forming apparatus according to the first aspect, the calculation unit divides the plurality of light emitting elements into a plurality of regions, and calculates the integrated value for each of the divided regions. The determination unit performs the determination based on an integrated value for each region.

  The invention according to claim 8 is a calculation unit that calculates an integrated value related to a light emission time of a plurality of light emitting elements that are turned on based on image data, and the plurality of light emission units based on the integrated value calculated by the calculation unit. A control device comprising: a determination unit configured to determine whether or not to adjust a lighting condition set by an element.

According to a ninth aspect of the present invention, in the control device according to the eighth aspect, the adjusting means for adjusting the lighting conditions set in the plurality of light emitting elements based on the result of the determination by the determining means. In addition, the adjustment unit adjusts an overall light amount setting value for setting an entire light amount of the plurality of light emitting elements.
According to a tenth aspect of the present invention, in the control device according to the eighth aspect, the adjusting means for adjusting the light emission conditions set in the plurality of light emitting elements based on the result of the determination by the determining means. In addition, the adjustment unit may perform thinning or interpolation of the image data for correcting a positional deviation of the plurality of light emitting elements.

The invention according to claim 11 is the control device according to claim 8, wherein the calculation means divides the plurality of light emitting elements into a plurality of regions, calculates the integrated value for each of the divided regions, The determination means performs the determination based on an integrated value for each region.
According to a twelfth aspect of the present invention, in the control device according to the tenth aspect, the adjusting means for adjusting the light emission conditions set in the plurality of light emitting elements based on the result of the determination by the determining means. In addition, the adjustment unit may perform the thinning or interpolation of the image data for correcting the positional deviation of the plurality of light emitting elements for each region.

According to the first aspect of the present invention, it is possible to reduce the frequency of adjustment of various setting conditions performed on the exposure apparatus as compared with the case where the present invention is not adopted.
According to claim 2 of the present invention, when the exposure condition is adjusted by taking the product of the light emission time per lighting and the number of the image data set to the lighting state as a scale, the present invention is not adopted. In comparison, productivity in image formation can be improved.
According to the third aspect of the present invention, the determination is made in accordance with the timing of adjusting the exposure condition, and the accuracy of the determination as to whether or not to adjust the exposure condition is higher than in the case where the present invention is not adopted. Can be increased.

According to the fourth aspect of the present invention, the determination can be made at a timing suitable for the type of exposure condition to be adjusted.
According to the fifth aspect of the present invention, it is possible to make a determination corresponding to the characteristics of the photoreceptor such that the sensitivity fluctuation increases as the integrated value of the light emission time of the light emitting element increases.
According to the sixth aspect of the present invention, it is possible to make a determination corresponding to the characteristics of the light emitting element such that when the power consumption of the light emitting element is increased, the life of the light emitting element is shortened and the amount of light is reduced.
According to the seventh aspect of the present invention, the state of the light emitting element can be grasped in detail for each region from the integrated value of the light emission time for each divided region, and compared with the case where the present invention is not adopted, exposure is performed. It is possible to further improve the accuracy of the determination as to whether or not to adjust the conditions.

According to the eighth aspect of the present invention, it is possible to reduce the frequency of adjustment of various setting conditions performed on the exposure apparatus as compared with the case where the present invention is not adopted.
According to the ninth aspect of the present invention, as compared with the case where the present invention is not adopted, it is possible to adjust the light emitting element corresponding to the sensitivity variation of the photosensitive member, the variation of the developer, and the like at an appropriate timing. Productivity in formation can be improved.
According to the tenth aspect of the present invention, as compared with the case where the present invention is not adopted, the adjustment of the light emitting element corresponding to the positional deviation of the light emitting element due to heat generation can be performed at an appropriate timing, and in image formation Productivity can be improved.
According to the eleventh aspect of the present invention, compared to the case where the present invention is not adopted, the state of the light emitting element can be grasped in detail for each region from the integrated value of the light emission time for each divided region. It is possible to further improve the accuracy of the determination as to whether or not to adjust the conditions.
According to the twelfth aspect of the present invention, the positional deviation of the light emitting element can be finely adjusted for each region from the integrated value of the light emission time for each divided region, as compared with the case where the present invention is not adopted.

[Embodiment 1]
FIG. 1 is a diagram illustrating an example of the overall configuration of an image forming apparatus 1 to which the exemplary embodiment is applied. An image forming apparatus 1 shown in FIG. 1 is a so-called tandem digital color printer, and includes an image forming process unit 10 that forms an image corresponding to image data of each color, and a control unit that controls the operation of the entire image forming apparatus 1. 30, for example, an image processing unit 35 that performs predetermined image processing on image data received from an external device such as a personal computer (PC) 3 or an image reading device 4, and a main power source 70 that supplies power to each unit.

The image forming process unit 10 includes four image forming units 11Y, 11M, 11C, and 11K (hereinafter, simply referred to 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 image carrier that forms an electrostatic latent image and holds a toner image, a charger 13 that uniformly charges the surface of the photosensitive drum 12 at a predetermined potential, An LED print head (LPH) 14 for exposing the photosensitive drum 12 charged by the developing device 13 based on image data; a developing device 15 for developing an electrostatic latent image formed on the photosensitive drum 12; A cleaner 16 for cleaning the surface of the body drum 12 is provided.
Each image forming unit 11 is configured in substantially the same manner except for the toner stored in the developing device 15. The image forming units 11Y, 11M, 11C, and 11K form yellow (Y), magenta (M), cyan (C), and black (K) toner images, respectively.

  Further, the image forming process unit 10 includes an intermediate transfer belt 20 onto which the color toner images formed on the photosensitive drums 12 of the image forming units 11 are transferred, and the color toner images of the image forming units 11 to the intermediate transfer belt. A primary transfer roll 21 that sequentially transfers (primary transfer) to 20 and a secondary transfer roll 22 that collectively transfers (secondary transfer) the toner image transferred onto the intermediate transfer belt 20 onto a sheet P that is a recording material (recording paper). And a fixing device 80 for fixing the second-transferred toner image on the paper P.

  In the image forming apparatus 1 of the present embodiment, the image forming process unit 10 performs an image forming operation based on various control signals supplied from the control unit 30. That is, the image data input from the PC 3 or the image reading device 4 under the control of the control unit 30 is subjected to predetermined image processing by the image processing unit 35, and each image forming unit 11 is connected via an interface (not shown). To be supplied. For example, in the black (K) image forming unit 11K, the photosensitive drum 12 is uniformly charged at a predetermined potential by the charger 13 while rotating in the arrow A direction, and the image transmitted from the image processing unit 35 is transmitted. The exposure is performed by the LPH 14 that emits light based on the data. Thereby, an electrostatic latent image related to a black (K) color image is formed on the photosensitive drum 12. The electrostatic latent image formed on the photosensitive drum 12 is developed by the developing device 15, and a black (K) toner image is formed on the photosensitive drum 12. Similarly, yellow (Y), magenta (M), and cyan (C) color toner images are formed in the image forming units 11Y, 11M, and 11C, respectively.

  Each color toner image formed by each image forming unit 11 is sequentially electrostatically attracted onto the intermediate transfer belt 20 that circulates and moves in the direction of arrow B in the primary transfer portion T1 where the primary transfer roll 21 is disposed. As a result, a composite toner image in which the toners of the respective colors are superimposed is formed on the intermediate transfer belt 20. The synthetic toner image on the intermediate transfer belt 20 is conveyed to the secondary transfer portion T2 where the secondary transfer roll 22 is disposed as the intermediate transfer belt 20 moves. Further, the paper P is transported from the paper holding unit 40 to the secondary transfer unit T2 in accordance with the timing at which the toner image is transported to the secondary transfer unit T2. Then, in the secondary transfer portion T <b> 2, the composite toner image is collectively electrostatically transferred onto the paper P by the transfer electric field formed by the secondary transfer roll 22.

The sheet P on which the composite toner image has been electrostatically transferred is peeled off from the intermediate transfer belt 20, guided to the conveyance guide 23, and conveyed to the fixing device 80. In the fixing device 80, the synthetic toner image is fixed by receiving a fixing process using heat and pressure. Then, the fixed sheet P is conveyed to a paper discharge stacking unit 45 provided in a discharge unit of the image forming apparatus 1.
On the other hand, toner (transfer residual toner) adhering to the intermediate transfer belt 20 after the secondary transfer is removed from the surface of the intermediate transfer belt 20 by the belt cleaner 25 after the completion of the secondary transfer to prepare for the next image forming operation. .
In the image forming apparatus 1, such an image forming operation is repeatedly executed for the number of prints.

  Next, FIG. 2 is a diagram showing a configuration of the LED print head (LPH) 14. In FIG. 2, the LPH 14 is equipped with a housing 61 as a support, a self-scanning LED array (SLED) 63 as an example of exposure means, a signal generation circuit 100 for driving the SLED 63 and SLED 63 (see FIG. 3 in the subsequent stage), and the like. The LED circuit board 62, the rod lens array 64 for imaging the light emitted from the SLED 63 on the surface of the photosensitive drum 12, the holder 65 for supporting the rod lens array 64 and shielding the SLED 63 from the outside, and the housing 61 for the rod lens array A leaf spring 66 that pressurizes in 64 directions is provided.

The housing 61 is formed of a metal block such as aluminum or SUS or a sheet metal, 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 SLED 63 and the rod lens array 64 maintain a predetermined optical positional relationship. 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 via the housing 61 so as to maintain the optical 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.

As shown in FIG. 3 (plan view of the LED circuit board 62), the LED circuit board 62 includes, for example, SLEDs 63 composed of 58 SLED chips (CHIP1 to CHIP58) in parallel with the axial direction of the photosensitive drum 12. Are arranged in a line with high accuracy. In this case, the SLED chips are alternately arranged in a staggered manner so that the light emitting elements (LEDs) arranged in the SLED chips (CHIP1 to CHIP58) are continuously arranged at the connection portion between the SLED chips. .
Further, the LED circuit board 62 stores a signal generation circuit 100 and a level shift circuit 104 that generate a signal (drive signal) for driving the SLED 63, a three-terminal regulator 101 that outputs a predetermined voltage, light amount correction data of the SLED 63, and the like. A harness 103 that receives signals from the EEPROM 102, the control unit 30, and the image processing unit 35 and supplies power from the main power supply 70 is provided.

Here, FIG. 4 is a diagram illustrating the SLED 63. The SLED 63 of the present embodiment is supplied with various drive signals from the signal generation circuit 100 and the level shift circuit 104. That is, the signal generation circuit 100 performs transfer processing CK1R and CK1C and transfer signals CK2R and CK2C, which sequentially set each LED arranged in each SLED chip constituting the SLED 63 to a lightable state along the LED array, and image processing. Based on the image data from the unit 35, a lighting signal ΦI for sequentially lighting each LED is generated. Then, the transfer signals CK1R and CK1C and the transfer signals CK2R and CK2C are output to the level shift circuit 104, and the lighting signal ΦI is output to the SLED 63.
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, and one end of each is connected to the input terminal of each SLED chip constituting the SLED 63, and the other end Is connected to the output terminal of the signal generation circuit 100. The level shift circuit 104 generates the transfer signal CK1 and the transfer signal CK2 based on the transfer signals CK1R and CK1C and the transfer signals CK2R and CK2C output from the signal generation circuit 100, and outputs them to each SLED chip.

On the other hand, each SLED chip constituting the SLED 63 of the present embodiment includes, for example, 128 thyristors S1 to S128 as switching elements, 128 LEDs L1 to L128 as an example of a light source, and 128 diodes D1 to D128. The main constituent elements are the 128 resistors R1 to R128 and the transfer current limiting resistors R1A and R2A for preventing excessive current from flowing through the signal lines Φ1 and Φ2.
The anode terminals (input terminals) A1 to A128 of the thyristors S1 to S128 are connected to the power supply line 105, and the drive voltage VDD (VDD = + 3.3V) from the three-terminal regulator 101 (see FIG. 3) via the power supply line 105. ) Is supplied.
On the other hand, the gate terminals (control terminals) G1 to G128 of the thyristors S1 to S128 are connected to the power supply line 106 via resistors R1 to R128 provided corresponding to the thyristors S1 to S128, respectively. Is grounded (GND).

Further, the transfer signal CK1 from the signal generation circuit 100 and the level shift circuit 104 is transferred to the transfer current limiting resistor R1A at the cathode terminals (output terminals) K1, K3,... K127 of the odd-numbered thyristors S1, S3,. Sent through. .., S128 of the even-numbered thyristors S2, S4,..., S128 receive the transfer signal CK2 from the signal generation circuit 100 and the level shift circuit 104 via the transfer current limiting resistor R2A. Sent.
Furthermore, the cathode terminals of the LEDs L1 to L128 are connected to the signal generation circuit 100 and the lighting signal ΦI is transmitted.

  The signal generation circuit 100 according to the present embodiment then transfers the transfer signals CK1R and CK1C and the transfer signals CK2R and CK2C from a high level (hereinafter referred to as “H”) to a low level (hereinafter referred to as “L”). And “L” to “H”. Accordingly, the potential of the transfer signal CK1 output from the level shift circuit 104 is repeatedly set from “H” to “L”, “L” to “H”, and the transfer signal CK2 output alternately The potential is repeatedly set from “H” to “L” and from “L” to “H”. Accordingly, for example, in each SLED chip, transfer operations of OFF → ON → OFF are sequentially performed in the odd-numbered thyristors S1, S3,. Further, in the even-numbered thyristors S2, S4,..., S128, the transfer operation is sequentially performed from OFF to ON to OFF. Thereby, the thyristors S1 to S128 are sequentially subjected to the transfer operation of OFF → ON → OFF in the order of S1 → S2 →,..., S127 → S128, and the lighting signal ΦI is output in synchronization therewith. Accordingly, the LEDs L1 to L128 are sequentially turned on in the order of L1 → L2 →,... → L127 → L128.

Next, the configuration of the signal generation circuit 100 will be described in detail.
FIG. 5 is a block diagram illustrating a configuration of the signal generation circuit 100. The signal generation circuit 100 includes an image data development unit 110, a density unevenness correction data unit 112, a timing signal generation unit 114, a reference clock generation unit 116, and lighting time control / corresponding to each SLED chip (CHIP1 to CHIP58). Driving units 118-1 to 118-58, an integrating unit 120, and a pulse measuring unit 121 are provided.
The image data development unit 110 sets the image data serially transmitted from the image processing unit 35 for each SLED chip (CHIP1 to CHIP58) such as 1st to 128th dot, 129th to 256th dot, ..., 7297 to 7424th dot. Is divided into image data. The divided image data is output to the lighting time control / drive units 118-1 to 118-58.
The pulse measuring unit 121 is an example of a measuring unit, and the number of image data having a value of “1” for setting the LED in the image data serially transmitted from the image processing unit 35 to ON (lighting state) ( Measure the number of pulses). Then, data relating to the number of image data having a measured value of “1” (ON) (pulse number data) is output to the integrating unit 120.

The density unevenness correction data unit 112 acquires light amount correction data for each LED from the EEPROM 102 in which the light amount correction data for each LED is stored. Then, based on the light amount correction data for each LED, density unevenness correction data Corr for correcting image density unevenness caused by variations in the light amount for each LED in the SLED 63 is generated. The density unevenness correction data Corr is output to the lighting time control / drive units 118-1 to 118-58 in synchronization with the data read signal from the density unevenness correction data unit 112.
The density unevenness correction data Corr is formed as 8-bit (0 to 255) data in the present embodiment.
The light amount correction data for each LED stored in the EEPROM 102 is downloaded to the density unevenness correction data unit 112 when the image forming apparatus 1 is turned on.

As shown in FIG. 6 (a block diagram illustrating the configuration of the reference clock generation unit 116), the reference clock generation unit 116 includes a crystal oscillator 140, a frequency divider 1 / M142, a frequency divider 1 / N144, and a phase comparator. 146 and a voltage controlled oscillator 148, and a lookup table (LUT) 132 as a memory.
In the LUT 132, the combination of the pulse number setting value width and the frequency division ratios M and N set in correspondence with the light amount adjustment data (instruction signal for instructing the total light amount of the LPH 14) output from the control unit 30 is the light amount. It is stored in the table as a set of data corresponding to the adjustment data. Then, the LUT 132 outputs the pulse number setting value width in the combination corresponding to the light amount adjustment data from the control unit 30 to the lighting time control / drive units 118-1 to 118-58 and the integration unit 120. The LUT 132 outputs the frequency division ratios M and N in the combination corresponding to the light amount adjustment data to the PLL circuit 134.

In the PLL circuit 134, the crystal oscillator 140 is connected to the frequency divider 1 / N144, oscillates at a predetermined frequency (crystal oscillator frequency Fclk_i), and outputs the oscillated signal to the frequency divider 1 / N144. The frequency divider 1 / N 144 divides the signal oscillated by the crystal oscillator 140 based on the frequency division ratio N from the LUT 132. The phase comparator 146 compares the output signal from the frequency divider 1 / M142 with the output signal from the frequency divider 1 / N144. The control voltage supplied to the voltage controlled oscillator 148 is controlled according to the comparison result (phase difference) by the phase comparator 146. The voltage controlled oscillator 148 outputs a reference clock signal having an oscillation frequency (reference clock frequency Fclkpwm) based on the control voltage. The reference clock signal having the reference clock frequency Fclkpwm is output to all the lighting time control / drive units 118-1 to 118-58 and the integrating unit 120.
The voltage controlled oscillator 148 is also connected to the frequency divider 1 / M142, and the reference clock signal output from the voltage controlled oscillator 148 is also branched and input to the frequency divider 1 / M142. The frequency divider 1 / M 142 divides the clock signal fed back from the voltage controlled oscillator 148 based on the frequency division ratio M from the LUT 132.

The timing signal generator 114 generates the transfer signals CK1R and CK1C and the transfer signals CK2R and CK2C in synchronization with the horizontal synchronization signal (Lsync) from the control unit 30 based on the reference clock signal from the reference clock generator 116. To do. The transfer signals CK1R and CK1C and the transfer signals CK2R and CK2C are transferred to the LPH 14 as the transfer signal CK1 and the transfer signal CK2 via the level shift circuit 104.
Further, the timing signal generation unit 114 reads out image data corresponding to each LED from the image data development unit 110 in synchronization with the Lsync signal from the control unit 30 based on the reference clock signal from the reference clock generation unit 116. And a data read signal for reading out density unevenness correction data corresponding to each LED from the density unevenness correction data unit 112. Further, the timing signal generation unit 114 synchronizes the lighting time control / drive units 118-1 to 118-58 with the Lsync signal from the control unit 30 based on the reference clock signal from the reference clock generation unit 116. Then, a trigger signal (TRG) for starting lighting of the SLED 63 is output.

The lighting time control / drive units 118-1 to 118-58 correct the lighting time of each LED based on the density unevenness correction data and the delay selection data, and control signals (lighting signals) for lighting each LED of the SLED 63. ΦI1 to ΦI58 are generated.
Specifically, the lighting time control / drive units 118-1 to 118-58 are presettable digital one-shot multi, as shown in FIG. 7 (block diagram for explaining the configuration of the lighting time control / drive unit 118). A vibrator (PDOMV) 160, a linearity correction unit 162, and an AND circuit 170 are provided.
When the image data from the image data development unit 110 is “1” (ON), the AND circuit 170 outputs the trigger signal (TRG) from the timing signal generation unit 114 to the PDOMV 160 and the image data is “0” (OFF). ), The trigger signal is set not to be output. The PDOMV 160 generates a lighting pulse signal having the number of clocks corresponding to the density unevenness correction data Corr in synchronization with the trigger signal from the AND circuit 170.

The linearity correction unit 162 corrects and outputs the lighting pulse signal from the PDOMV 160 in order to correct the variation in the light emission start time of each LED in the SLED 63. Specifically, the linearity correction unit 162 includes a plurality of delay circuits 164 (eight in this embodiment, 164-0 to 164-7), a delay selection register 166, a delay signal selection unit 165, and an AND circuit 167. , An OR circuit 168, and a lighting signal selector 169.
Each of the delay circuits 164-0 to 164-7 is set with a different time for delaying the lighting pulse signal from the PDOMV 160. The delay selection register 166 stores delay selection data Offset for each LED in the SLED 63 and lighting signal selection data. The delay selection data Offset and lighting signal selection data for each LED are measured in advance and stored in the EEPROM 102. The delay selection data Offset and the lighting signal selection data stored in the EEPROM 102 are downloaded to the delay selection register 166 when the image forming apparatus 1 is powered on.

The delay signal selection unit 165 selects one of the outputs from the delay circuits 164-0 to 164-7 based on the delay selection data Offset stored in the delay selection register 166. The AND circuit 167 is a logical product of the lighting pulse signal from the PDOMV 160 and the delayed lighting pulse signal selected by the delay signal selection unit 165, that is, both the lighting pulse signal before the delay and the lighting pulse signal after the delay are in the lighting state. If so, a lighting pulse signal is output. The OR circuit 168 is a logical sum of the lighting pulse signal from the PDOMV 160 and the delayed lighting pulse signal selected by the delay signal selection unit 165, that is, at least one of the lighting pulse signal before the delay and the lighting pulse signal after the delay is in the lighting state. If so, a lighting pulse signal is output.
The lighting signal selection unit 169 selects one of the outputs from the AND circuit 167 or the OR circuit 168 based on the lighting selection data stored in the delay selection register 166. Then, the selected lighting pulse signal is output to the LPH 14 via the MOSFET 172 as the lighting signal ΦI.

Next, the lighting pulse widths of the lighting signals ΦI1 to ΦI58 output from the lighting time control / drive units 118-1 to 118-58 to the LPH 14 will be described.
In the lighting time control / drive units 118-1 to 118-58, the PDOMV 160 sets the reference pulse width BASE based on the pulse number setting value width corresponding to the light amount adjustment data and the reference clock signal of the reference clock frequency Fclkpwm. That is, the reference pulse width BASE is set by the following equation (1). The reference pulse width BASE is a reference for the lighting pulse width in each LED.
BASE = width / Fclkpwm (1)
Then, the lighting time control / drive units 118-1 to 118-58 correct the reference pulse width BASE for each LED based on the density unevenness correction data Corr and the delay selection data Offset. That is, the lighting pulse width of each LED is set by the following equation (2), for example.
Lighting pulse width = BASE · (1 + Corr / 128) + Offset (2)
Here, the density unevenness correction data Corr of this embodiment is composed of 8-bit data (0 to 255). Therefore, in the setting of the equation (2), the reference pulse width BASE is set to the maximum correction value / minimum correction value. = Lighting pulse width correction is performed with a correction width of 3.
In this way, by setting the lighting pulse width corrected for each LED with reference to the reference pulse width BASE by the equation (2), the light amount characteristic of each LED arranged in the LPH 14 substantially matches the target light amount characteristic. Therefore, the light quantity of each LED is set to be within a predetermined range. Therefore, the lighting time control / drive units 118-1 to 118-58 function as light emission time setting means.

Thus, the reference pulse width BASE is a reference for the lighting pulse width set for each LED, and is set based on the light amount adjustment data from the control unit 30.
However, due to fluctuations in the accumulated usage time of the image forming apparatus 1 and environmental conditions, for example, sensitivity fluctuations of the photosensitive drum 12, fluctuations in the latent image potential (dark part potential V _H and bright part potential V _L ), and further the developing device. 15 changes in the developer. In some cases, the toner image density fluctuates due to these factors, and the image quality deteriorates.
For this reason, in the image forming apparatus 1 of the present embodiment, the total light amount at the LPH 14 (the light amount of the entire LED in the LPH 14) is adjusted at predetermined time intervals (intervals), and the sensitivity fluctuation of the photosensitive drum 12 and the like. Corresponds to changes in developer. For example, in the initial state where the sensitivity of the photosensitive drum 12 is high, the entire light amount of the LPH 14 is set to a low state, and when the sensitivity of the photosensitive drum 12 is lowered, the entire light amount of the LPH 14 is set to be high. As a result, the image quality is maintained in accordance with the accumulated use time of the image forming apparatus 1 and environmental fluctuations.
The light amount adjustment data for each predetermined interval is set by, for example, reading the densities of a plurality of reference density patterns with different gradations formed in each image forming unit 11 with a detection sensor. Therefore, during that time, the image forming operation of the image forming apparatus 1 cannot be performed, and the productivity is lowered.

Further, apart from the adjustment of the light amount adjustment data, for example, expansion and contraction in the longitudinal direction (main scanning direction) occurs in the LED circuit board 62 due to the influence of heat accompanying light emission of each LED arranged in the LPH 14. For this reason, in the LPH 14 arranged in each image forming unit 11, there may be a deviation in the main scanning direction at the arrangement position of each LED. Therefore, in the image forming apparatus 1 of the present embodiment, the exposure position of the LPH 14 is adjusted every predetermined interval.
The exposure position of the LPH 14 is adjusted by, for example, reading the position of the position correction pattern formed by each image forming unit 11 with a detection sensor. Therefore, during that period, the image forming operation of the image forming apparatus 1 cannot be performed, and the productivity is reduced as in the case of setting the light amount adjustment data.

Incidentally, for example, the sensitivity fluctuation of the photosensitive drum 12 depends on the accumulated value of the exposure amount from the LPH 14 received by the photosensitive drum 12. The expansion / contraction amount of the LED circuit board 62 depends on the cumulative value of the light emission amount of each LED in the LPH 14 because the influence of heat accompanying the light emission of the LED is a main factor.
Therefore, in the image forming apparatus 1 according to the present embodiment, the number of pulses of image data transmitted serially from the image processing unit 35, that is, an image having a value of “1” that sets each LED to a lighting state (ON). The product (integrated value) of the number of data (number of pulses) and the reference pulse width BASE that serves as a reference for the lighting pulse width set for each LED is calculated. Here, the integrated value of the number of pulses and the reference pulse width BASE corresponds to the cumulative value of the lighting times of all LEDs arranged in the LPH 14. Then, the integration of the number of pulses and the reference pulse width BASE at one or both of every predetermined interval for newly setting the light amount adjustment data of the LPH 14 and every predetermined interval for adjusting the exposure position of the LPH 14 It is determined whether or not the value has reached a predetermined value or more.

As a result of the determination, when the integrated value of the number of pulses and the reference pulse width BASE reaches a predetermined value or more, the light amount adjustment data of the LPH 14 is newly set. Also, the exposure position of the LPH 14 is adjusted. On the other hand, when the integrated value of the number of pulses and the reference pulse width BASE does not reach a predetermined value, the light amount adjustment data for the LPH 14 is not newly set. Further, the exposure position of the LPH 14 is not adjusted. In this way, by using the product (integrated value) of the number of pulses and the reference pulse width BASE as a scale, it is determined whether or not to newly set the light amount adjustment data of the LPH 14 or to adjust the exposure position of the LPH 14. The frequency of setting the light amount adjustment data and adjusting the exposure position is reduced, and the productivity in image formation is improved.
Note that it is determined whether or not to adjust the LPH 14 exposure position and a predetermined value related to the integrated value of the number of pulses and the reference pulse width BASE when determining whether or not to newly set the light amount adjustment data of the LPH 14. The predetermined value regarding the integrated value of the number of pulses and the reference pulse width BASE may be the same value or different values.

In the image forming apparatus 1 according to the present embodiment, the product (integrated value) of the number of pulses of the image data and the reference pulse width BASE is calculated by the integration unit 120 as an example of a calculation unit.
As described above, the integration unit 120 of the present embodiment has data (pulse number data) P regarding the number of image data having a value of “1” (ON) in the image data transmitted from the image processing unit 35. Is acquired from the pulse measurement unit 121. Further, the pulse number setting value width and the reference clock signal (reference clock frequency Fclkpwm) corresponding to the light amount adjustment data output from the control unit 30 are acquired from the reference clock generation unit 116.
Then, the accumulator 120 calculates the reference pulse width BASE in the same manner as the above equation (1).
Furthermore, the integrating unit 120 calculates a product (integrated value) of the calculated reference pulse width BASE and the pulse number data P acquired from the pulse measuring unit 121 at predetermined intervals. That is, the calculation of the following equation (3) is performed to calculate the integrated lighting pulse width TPW within a predetermined interval.
TPW = BASE · P (3)
The integrating unit 120 sends the integrated lighting pulse width TPW within the calculated predetermined interval to the control unit 30.
In addition, in the integration unit 120, when calculating the integrated lighting pulse width TPW, the density unevenness correction data Corr for each LED is acquired from the density unevenness correction data unit 112, and the integrated lighting pulse width TPW in consideration of the density unevenness correction data Corr is obtained. May be calculated.

The control unit 30 as an example of a determination unit that acquires the integrated lighting pulse width TPW from the integrating unit 120 determines whether or not the integrated lighting pulse width TPW is greater than or equal to a predetermined value at every predetermined interval. As a result of the determination, if the integrated lighting pulse width TPW is greater than or equal to a predetermined value, the control unit 30 performs new setting of the light amount adjustment data of the LPH 14 and adjustment of the exposure position of the LPH 14.
On the other hand, if the integrated lighting pulse width TPW has not reached the predetermined value, the control unit 30 maintains the state as it is without newly setting the light amount adjustment data of the LPH 14 or adjusting the exposure position of the LPH 14. To do.
In this way, by using the integrated lighting pulse width TPW as a scale, new setting of the light amount adjustment data of the LPH 14 and adjustment of the exposure position of the LPH 14 are performed under the condition that the integrated lighting pulse width TPW is equal to or greater than a predetermined value. Thus, the frequency of adjusting the exposure position of the LPH 14 and the generation of the light amount adjustment data are reduced to improve the productivity in image formation.

It should be noted that the predetermined value related to the integrated value when determining whether or not to newly set the light amount adjustment data of the LPH 14 and the integrated value when determining whether or not to adjust the exposure position of the LPH 14 are related. When the predetermined value is set to a different value, the control unit 30 may perform new setting of the light amount adjustment data of the LPH 14 and adjustment of the exposure position of the LPH 14 at different timings.
In addition, in the integration unit 120 of the present embodiment, the integrated lighting pulse width TPW within a predetermined interval is calculated. However, the current value for driving the LPH 14 is further integrated into the integrated lighting pulse width TPW, and within the predetermined interval. You may calculate the integrated electric energy which drives LPH14. Then, using the integrated power amount as a scale, the new setting of the light amount adjustment data of the LPH 14 and the adjustment of the exposure position of the LPH 14 can be performed under the condition that the integrated power amount becomes a predetermined value or more.
Furthermore, in the image forming apparatus 1 according to the present embodiment, the integration unit 120 and the pulse measurement unit 121 are provided in the signal generation circuit 100. However, the integration unit 120 and the pulse measurement unit 121 are provided in the control unit 30. It is good.

Subsequently, when it is determined that the integrated lighting pulse width TPW is greater than or equal to a predetermined value when a predetermined interval has elapsed, the adjustment of the exposure condition (LED lighting condition) performed in the image forming apparatus 1 of the present embodiment is performed. The adjustment of the exposure position of the LPH 14 as an example and the adjustment of the light amount adjustment data for setting the total light amount relating to the LPH 14 will be described.
First, adjustment of the exposure position of the LPH 14 will be described. When adjusting the exposure position, first, a position correction pattern is formed on the photosensitive drum 12 of each image forming unit 11. Then, the position correction pattern formed on each photosensitive drum 12 is transferred to the intermediate transfer belt 20, and a detection sensor 50 (see FIG. 1) disposed downstream of the image forming unit 11K in the conveyance direction of the intermediate transfer belt 20. Thus, the position of the position correction pattern is detected. Position data in the sub-scanning direction (sub-scanning direction position data) and position data in the main scanning direction (main scanning direction position data) of the position correction pattern detected by the detection sensor 50 are sent to the control unit 30. Then, the positional deviation amounts in the sub-scanning direction and the main scanning direction are calculated, and the exposure position adjustment of the LPH 14 in the sub-scanning direction and the main scanning direction is performed based on the calculated positional deviation amounts in the sub-scanning direction and the main scanning direction. Is called.

FIG. 8 is a diagram illustrating an example of a position correction pattern transferred onto the intermediate transfer belt 20. Each image forming unit 11 of the present embodiment forms a position correction pattern as shown in FIG. 8 in, for example, both end regions of the photosensitive drum 12 when adjusting the exposure position of the LPH 14.
As shown in FIG. 8, the image forming unit 11Y forms a yellow parallel pattern YP and a 45 ° inclined pattern YQ, which are reference colors when performing exposure position adjustment in the present embodiment. Further, the image forming unit 11M forms a magenta parallel pattern MP and a 45 ° inclined pattern MQ. The image forming unit 11C forms a cyan parallel pattern CP and a 45 ° inclined pattern CQ. The image forming unit 11K forms a black parallel pattern BP and a 45 ° inclined pattern BQ.
Here, the parallel patterns YP, MP, CP, and KP are used when performing exposure position adjustment in the sub-scanning direction. The 45 ° tilt patterns YQ, MQ, CQ, and KQ are used when adjusting the exposure position in the main scanning direction.

  The detection sensor 50 detects the position of each of the parallel patterns YP, MP, CP, KP on the intermediate transfer belt 20, and uses the detected position as position data in the sub-scanning direction to the control unit 30 which is an example of an adjustment unit. send. For example, using the timing at which the sub-scanning direction position data is transmitted, the control unit 30 calculates the time interval of the timing at which the other color parallel patterns MP, CP, KP pass the detection sensor 50 with the parallel pattern YP as a reference. . That is, as shown in FIG. 8, the time interval P1 between the passage timing of the parallel pattern YP and the passage timing of the parallel pattern MP, the time interval P2 between the passage timing of the parallel pattern YP and the passage timing of the parallel pattern CP, the parallel pattern A time interval P3 between the passage timing of YP and the passage timing of the parallel pattern BP is calculated. Then, the control unit 30 adjusts the exposure timing in the sub-scanning direction of the LPH 14 in each of the image forming units 11 based on the calculated time intervals P1, P2, and P3.

The detection sensor 50 is an example of an adjustment unit that detects the position in the width direction of the intermediate transfer belt 20 of each of the 45 ° inclined patterns YQ, MQ, CQ, and KQ, and uses the detected position as position data in the main scanning direction. This is sent to a certain control unit 30. The control unit 30 calculates the positional deviation amounts of the 45 ° inclination patterns MQ, CQ, and KQ using the position of the 45 ° inclination pattern YQ in the main scanning direction as a reference position. That is, as shown in FIG. 8, the positional deviation amount L1 between the 45 ° inclination pattern YQ and the 45 ° inclination pattern MQ, the positional deviation amount L2 between the 45 ° inclination pattern YQ and the 45 ° inclination pattern CQ, and the 45 ° inclination pattern. A positional deviation amount L3 between YQ and the 45 ° inclined pattern BQ is calculated. The control unit 30 thins out the image data and interpolates the image data with respect to the image data output from the image processing unit 35 to each of the image forming units 11 based on the calculated misregistration amounts L1, L2, and L3. And so on. For example, if the position in the main scanning direction is shifted from the reference position (YQ) toward the end in the main scanning direction, it is determined that the LED circuit board 62 is stretched in the main scanning direction, and image data is thinned out. To reduce the image width in the main scanning direction. If the position in the main scanning direction is shifted from the reference position (YQ) toward the center in the main scanning direction, it is determined that the LED circuit board 62 is contracted in the main scanning direction, and image data interpolation is performed. Then, the image width in the main scanning direction is enlarged.
Thereby, the exposure position adjustment of the LPH 14 in the sub-scanning direction and the main scanning direction is performed.

Next, a new setting of the light amount adjustment data regarding the LPH 14 will be described. FIG. 9 is a diagram showing an example of a plurality of reference density patterns with different gradations transferred onto the intermediate transfer belt 20. In the example shown in FIG. 9, for example, in the yellow (Y) image forming unit 11Y, two gradation reference density patterns YH-1 and YH-2 at a high potential level and two at a low potential level. In this example, gradation reference density patterns YL-1 and YL-2 are formed. Therefore, in the image forming unit 11Y, a total of four reference density patterns are formed.
Similarly, in the example shown in FIG. 9, the image forming unit 11C for the reference density patterns MH-1, MH-2 and ML-1, ML-2 and cyan (C) by the magenta (M) image forming unit 11M. Reference density patterns CH-1, CH-2 and CL-1, CL-2, and black (K) image formation unit 11K, reference density patterns KH-1, KH-2, KL-1, and KL-2. It is formed.

For example, the density of the reference density pattern formed as shown in FIG. 9 is detected for each color by the detection sensor 50. Then, the detected density detection value of each color reference density pattern is sent to the control unit 30 which is an example of an adjusting unit. The control unit 30 obtains the total light amount to be set by the LPH 14 based on the detected toner image density data by a predetermined calculation, and sets new light amount adjustment data. In the LPH 14 of the present embodiment, the light amount adjustment data (instruction value) is formed as 10-bit (0 to 1023) data.
Then, the light amount adjustment data is sent from the control unit 30 to the signal generation circuit 100 of the LPH 14, and the lighting pulse width of each LED is set by, for example, the above formulas (1) and (2).

  As described above, in the image forming apparatus 1 according to the present embodiment, the light amount adjustment data of the LPH 14 is newly set at predetermined intervals with the integrated value of the number of pulses of the image data and the reference pulse width BASE as a scale. Whether or not and adjusting the exposure position of the LPH 14 is determined. As a result, the frequency of new setting of the light amount adjustment data of the LPH 14 and the adjustment of the exposure position of the LPH 14 is reduced, and the productivity in image formation is improved.

  In the present embodiment, the exposure apparatus (LPH14) using an LED as a light source has been described. However, the present invention can be similarly applied to an exposure apparatus using a surface emitting laser as a light source.

[Embodiment 2]
In the first embodiment, the integrated value of the number of pulses of the image data input to the LPH 14 and the reference pulse width BASE is calculated, and new setting of the light amount adjustment data of the LPH 14 and adjustment of the exposure position are performed at predetermined intervals. The configuration for determining whether or not to perform has been described. In the present embodiment, an integrated value of the number of pulses of image data input to the LPH 14 and the reference pulse width BASE is calculated for each region divided in the main scanning direction of the LPH 14, and the light quantity of the LPH 14 at predetermined intervals. A configuration for determining whether or not to newly adjust the adjustment data and adjust the exposure position will be described. In addition, the same code | symbol is used about the structure similar to Embodiment 1, and the detailed description is abbreviate | omitted here.

FIG. 10 is a block diagram illustrating a configuration of the signal generation circuit 100 of the LPH 14 according to the present embodiment. In the signal generation circuit 100 of the present embodiment, in addition to the configuration of the first embodiment, to which region of the image data that is serially transmitted from the image processing unit 35 is allocated in the main scanning direction. An image region determination unit 122 for determination is provided.
The image area determination unit 122 according to the present embodiment is an area in which the image data development unit 110 divides image data, as an example of an area to which image data having a value of “1” (ON) is assigned. That is, SLED chips (CHIP1 to CHIP58) are set. Therefore, the image area determination unit 122 determines to which of the SLED chips (CHIP1 to CHIP58) the image data “1” is assigned. Then, information relating to regions (CHIP1 to CHIP58) to which image data is allocated is output to integrating section 120.

  The accumulating unit 120 according to the present embodiment acquires pulse number data related to image data having a value of “1” (ON) in the image data transmitted from the image processing unit 35 from the pulse measuring unit 121. At the same time, information regarding the area to which the image data “1” is assigned is acquired from the image area determination unit 122. Then, the pulse number data for each region (CHIP1 to CHIP58) is calculated based on the pulse number data and the information regarding the region to which the image data “1” is assigned. Specifically, for example, the image region determination unit 122 time-divides the pulse number data from the pulse measurement unit 121 corresponding to the regions (CHIP1 to CHIP58), and each time-divided pulse number data is assigned to each region ( CHIP1 to CHIP58). Then, the integrating unit 120 calculates pulse number data P (CHIPn) for each region (CHIP1 to CHIP58).

Further, the integrating unit 120 acquires the pulse number setting value width and the reference clock signal (reference clock frequency Fclkpwm) corresponding to the light amount adjustment data output from the control unit 30 from the reference clock generation unit 116. Then, the accumulator 120 calculates the reference pulse width BASE in the same manner as the above equation (1).
Then, the integrating unit 120 calculates a product (integrated value) of the calculated reference pulse width BASE and the pulse number data P (CHIPn) of each region (CHIP1 to CHIP58) at each predetermined interval. That is, the calculation of the following equation (4) is performed to calculate the calculated lighting pulse width TPW (CHIPn) of each region (CHIP1 to CHIP58) within a predetermined interval. Here, n is an integer of 1 to 58.
TPW (CHIPn) = BASE · P (CHIPn) (4)
The integrating unit 120 sends the integrated lighting pulse width TPW (CHIPn) of each region (CHIP1 to CHIP58) within the calculated predetermined interval to the control unit 30.

The control unit 30 that has acquired the integrated lighting pulse width TPW (CHIPn) of each region (CHIP1 to CHIP58) from the integration unit 120 determines whether any of TPW (CHIPn) has a value greater than or equal to a predetermined value for each predetermined interval. Determine whether or not. As a result of the determination, for example, when any one of the integrated lighting pulse widths TPW (CHIPn) is equal to or larger than a predetermined value, the control unit 30 performs new setting of the light amount adjustment data of the LPH 14 and adjustment of the exposure position of the LPH 14. Do.
On the other hand, when none of the TPW (CHIPn) has reached the predetermined value, the control unit 30 does not newly set the light amount adjustment data of the LPH 14 and does not adjust the exposure position of the LPH 14 and keeps the state as it is. maintain.
In this way, with the integrated lighting pulse width TPW (CHIPn) of each region (CHIP1 to CHIP58) as a scale, for example, a new setting of the light amount adjustment data of LPH14 and the adjustment of the exposure position of LPH14 are performed for each region (CHIP1 to CHIP58). Production under the condition that any one of the integrated lighting pulse widths TPW (CHIPn) is equal to or greater than a predetermined value reduces the frequency of adjustment of the exposure position of the LPH 14 and generation of light amount adjustment data. Improved.

Further, the control unit 30 compares the maximum value and the minimum value of TPW (CHIPn) in each region, and when the difference between the maximum value and the minimum value is equal to or larger than a predetermined value, the image formation of the image forming apparatus 1 is performed. You may set so that operation | movement may be stopped. This suppresses an increase in the amount of variation in the LED arrangement position in the main scanning direction.
Further, the control unit 30 may be set to control to perform thinning of image data, interpolation of image data, or the like for image data in each region based on TPW (CHIPn) in each region. . For example, when TPW (CHIPn) is equal to or larger than a predetermined value, it is determined that the LED circuit board 62 where CHIPn is located is stretched in the main scanning direction, and image data is thinned out to obtain an image in the main scanning direction. Reduce the width. If TPW (CHIPn) is smaller than a predetermined value, it is determined that the LED circuit board 62 where CHIPn is located is contracted in the main scanning direction, and image data is interpolated to perform interpolation in the main scanning direction. Increase the image width.
Thereby, the position correction pattern is formed, and the exposure position is adjusted without adjusting the exposure position of the LPH 14 by detecting the position of the position correction pattern by the detection sensor 50 (see FIG. 1). .

  As described above, in the LPH 14 according to the present embodiment, the LPH 14 according to the present embodiment uses the integrated value of the number of pulses of the image data and the reference pulse width BASE for each region divided in the main scanning direction as a scale. At each interval, it is determined whether or not a new setting of the light amount adjustment data of the LPH 14 and an adjustment of the exposure position of the LPH 14 are performed. As a result, the frequency of new setting of the light amount adjustment data of the LPH 14 and the adjustment of the exposure position of the LPH 14 is reduced, and the productivity in image formation is improved.

1 is a diagram illustrating an example of the overall configuration of an image forming apparatus of the present invention. 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 SLED. It is a block diagram which shows the structure of a signal generation circuit. It is a block diagram explaining the structure of a reference clock generation part. It is a block diagram explaining the structure of lighting time control and a drive part. FIG. 6 is a diagram illustrating an example of a position correction pattern transferred onto an intermediate transfer belt. FIG. 4 is a diagram illustrating an example of a plurality of reference density patterns with different gradations transferred onto an intermediate transfer belt. It is a block diagram which shows the structure of a signal generation circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 10 ... Image forming process part, 11Y, 11M, 11C, 11K ... Image forming unit, 12 ... Photosensitive drum, 14 ... LED print head (LPH), 30 ... Control part, 62 ... LED circuit board 63 ... Self-scanning LED array (SLED), 64 ... Rod lens array, 100 ... Signal generation circuit, 110 ... Image data development unit, 112 ... Density unevenness correction data unit, 114 ... Timing signal generation unit, 116 ... Reference clock Generation unit, 118-1 to 118-58, lighting time control / driving unit, 120, integrating unit, 121, pulse measuring unit, 122, image region determining unit

Claims (12)

A plurality of light-emitting elements that are lit based on the image carrier and image data, and an exposure unit that exposes the image carrier;
Calculating means for calculating an integrated value relating to light emission times of the plurality of light emitting elements arranged in the exposure means;
An image forming apparatus comprising: a determination unit configured to determine whether or not to adjust an exposure condition set by the exposure unit based on the integrated value calculated by the calculation unit. A light emission time setting means for setting a light emission time per lighting of each of the plurality of light emitting elements arranged in the exposure means;
A measuring means for measuring the number of the image data for setting each of the plurality of light emitting elements to a lighting state;
The calculation unit calculates the integrated value based on the light emission time set by the light emission time setting unit and the number of the image data measured by the measurement unit. The image forming apparatus described.   The image forming apparatus according to claim 1, wherein the determination unit performs the determination every predetermined time.   The image forming apparatus according to claim 3, wherein the determination unit sets the predetermined time that varies depending on a type of the exposure condition.   The image forming apparatus according to claim 1, wherein the determination unit determines to adjust the exposure condition when the integrated value reaches a predetermined value or more.   2. The determination unit according to claim 1, wherein the determination unit calculates power consumption in the plurality of light emitting elements from the integrated value, and performs the determination based on whether the power consumption exceeds a predetermined value. Image forming apparatus. The calculation means divides the plurality of light emitting elements into a plurality of regions, calculates the integrated value for each of the divided regions,
The image forming apparatus according to claim 1, wherein the determination unit performs the determination based on an integrated value for each region. Calculating means for calculating an integrated value related to the light emission times of the plurality of light emitting elements that are turned on based on the image data;
A control unit comprising: a determination unit configured to determine whether or not to adjust lighting conditions set in the plurality of light emitting elements based on the integrated value calculated by the calculation unit; . An adjustment unit that adjusts the lighting condition set in the plurality of light emitting elements based on a result of the determination by the determination unit;
The control device according to claim 8, wherein the adjusting unit adjusts a total light amount setting value for setting a light amount as a whole of the plurality of light emitting elements. An adjustment unit for adjusting the light emission condition set in the plurality of light emitting elements based on a result of the determination by the determination unit;
The control device according to claim 8, wherein the adjustment unit performs thinning or interpolation of the image data for correcting a positional deviation of the plurality of light emitting elements. The calculation means divides the plurality of light emitting elements into a plurality of regions, calculates the integrated value for each of the divided regions,
The control device according to claim 8, wherein the determination unit performs the determination based on an integrated value for each region. An adjustment unit for adjusting the light emission condition set in the plurality of light emitting elements based on a result of the determination by the determination unit;
The control device according to claim 10, wherein the adjustment unit performs the thinning or interpolation of the image data for correcting the positional deviation of the plurality of light emitting elements for each region.

Images