JP6467461B2 - Image forming apparatus and exposure apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus and an exposure apparatus.

  An electrophotographic image forming apparatus forms an electrostatic latent image using an exposure device. There are individual differences in the exposure apparatus. Therefore, the adjustment value of the light amount for each individual and the adjustment value of the writing timing of the latent image in the main scanning direction are acquired in the assembly process and written in the nonvolatile memory (Patent Document 1).

JP 2014-228655 A

  In recent years, a common platform for exposure apparatuses has been developed. That is, since the image forming apparatus having a high process speed and the image forming apparatus having a low process speed are equipped with a common exposure apparatus, the manufacturing cost is reduced. The process speed is a parameter relating to the driving speed of a member for forming a toner image, for example, the peripheral speed of the photosensitive member.

  By the way, the adjustment value of the exposure apparatus differs for each process speed. A process for obtaining an adjustment value for each of a plurality of process speeds and a process for writing the adjustment value for each process speed in a memory are required, which increases man-hours. In addition, since the number of adjustment values stored in the memory increases, the manufacturing cost related to the memory also increases. Therefore, the present invention provides an apparatus that is advantageous with respect to man-hours and manufacturing costs.

According to the present invention, for example,
A photoreceptor,
Charging means for charging the photoreceptor;
Exposure means for exposing the photosensitive member to form an electrostatic latent image, the specification and the second process speed of a first image forming apparatus that forms an image with a first parameter that is a first process speed or a first resolution. Or an exposure unit having a common specification satisfying the specification of the second image forming apparatus that forms an image with the second parameter being the second resolution ;
Developing means for developing the electrostatic latent image to form a toner image;
Driving means for driving a light source of the exposure means;
The data indicating the relationship between the light quantity of the light source and the control value input to the driving means, the data acquired in the assembly process for the first process speed related to the driving speed of the member for forming the toner image Holding means not holding the data for a second process speed different from the first process speed;
When the process speed related to the driving speed of the member for forming the toner image is the first process speed by mounting the exposure unit on the first image forming apparatus, the data held in the holding unit The control value input to the driving unit is obtained based on the above, and when the process speed is the second process speed because the exposure unit is mounted on the second image forming apparatus, the control unit holds the control value. Control means for correcting the data about the first process speed, and obtaining a control value input to the driving means based on the corrected data,
An image forming apparatus is provided in which the driving unit drives the light source based on a control value obtained by the control unit.

  According to the present invention, an apparatus advantageous in terms of man-hours and manufacturing costs is provided.

Schematic sectional view of the image forming apparatus Schematic perspective view of exposure inspection equipment Diagram showing drive circuit The figure which shows the relationship between the light emission luminance of a laser beam, and the duty of a PWM signal Flow chart showing the light intensity adjustment process Flowchart showing main scanning position measurement process Flow chart showing the method for controlling the amount of light and the start timing Diagram showing the relationship between exposure and duty The figure which shows the function of CPU The figure which shows the function of CPU

[Image forming apparatus]
Although FIG. 1 shows an image forming apparatus capable of forming a full-color image, the present invention is also applicable to an image forming apparatus that forms a monochrome image. As shown in FIG. 1, the image forming apparatus 50 includes four image forming units corresponding to yellow, magenta, cyan, and black, respectively. In FIG. 1, the letter YMCK given at the end of the reference number indicates the toner color. The photosensitive drum 5 is a photoconductor, and is an image carrier that carries an electrostatic latent image or a toner image. The charger 7 is a charging roller that uniformly charges the surface of the photosensitive drum 5. The exposure device 9 is an optical scanning device that forms an electrostatic latent image by irradiating the surface of the photosensitive drum 5 with light according to an image signal. The developing device 8 develops the electrostatic latent image using toner to form a toner image. The primary transfer device 10 transfers the toner image carried on the photosensitive drum 5 to the intermediate transfer belt 3. Here, the four image forming units align and superimpose toner images of different colors to form a full color image.

  The intermediate transfer belt 3 is a kind of intermediate transfer body and is an endless belt. The intermediate transfer belt 3 is suspended from a driving roller 12, a tension roller 13, an idler roller 17, and a secondary transfer counter roller 18, and rotates in the direction of the arrow. The drive roller 12, the tension roller 13, and the secondary transfer counter roller 18 are support rollers that support the intermediate transfer belt 3.

  The paper feed cassette 1 is a storage for storing sheets P. The paper feed roller 2 picks up the sheet P stored in the paper feed cassette 1 and feeds it to the transport path. The registration roller pair 6 conveys the sheet P so that the timing at which the toner image conveyed by the intermediate transfer belt 3 arrives at the secondary transfer portion coincides with the timing at which the sheet P arrives at the secondary transfer portion. . The secondary transfer unit includes a secondary transfer roller 11 and a secondary transfer counter roller 18. The secondary transfer unit transfers the toner image to the sheet P. The cleaning unit 21 removes toner remaining on the intermediate transfer belt 3 without being transferred to the sheet P.

  The fixing device 14 fixes the toner image on the sheet P conveyed via the conveyance guide 19. The fixing device 14 includes a fixing roller 15 and a pressure roller 16 and applies heat and pressure to the toner image and the sheet P. The paper discharge roller pair 20 discharges the sheet P to the outside of the image forming apparatus 50.

  As shown in FIG. 1, the photosensitive drum 5 is an example of a photosensitive member. The charger 7 is an example of a charging unit that uniformly charges the photosensitive member. The exposure device 9 is an example of an exposure unit that exposes a photosensitive member according to an image signal to form an electrostatic latent image. The developing device 8 is an example of a developing unit that develops an electrostatic latent image using toner to form a toner image. The primary transfer device 10 and the intermediate transfer belt 3 are an example of a transfer unit that transfers a toner image onto a sheet P. The fixing device 14 is an example of a fixing unit that fixes the toner image on the sheet P.

[Optical scanning device]
As shown in FIG. 2, the exposure apparatus 9 has a laser unit 107. The drive circuit 130 supplies a drive current for causing the laser unit 107 to emit light. That is, the drive circuit 130 is an example of a drive unit that drives the light source of the exposure unit.

  The laser unit 107 emits laser light with a light emission amount corresponding to the drive current. The laser unit 107 has a laser diode LD as a light source (light emitting element) and a photodiode PD as a light receiving means. Laser light output from the laser unit 107 is incident on the collimator lens 134. The collimator lens 134 is an optical component that shapes the beam shape of the laser light. Thereafter, the laser light passes through several optical components and enters the polygon mirror 133. The polygon mirror 133 is a rotating polygon mirror that deflects the laser beam while rotating so that the laser beam scans the surface of the photosensitive drum 5. The laser beam reflected by the polygon mirror 133 passes through the fθ lens 132 and forms an image as a dot-like spot on the photosensitive drum 5. The fθ lens 132 is an optical component that converts laser light so that the laser light scans the photosensitive drum 5 at a constant speed. In FIG. 2, h0 indicates a position where the image height is zero. The image height may be referred to as a main scanning position.

  The mirror 131 is an optical component that guides the laser beam reflected by the polygon mirror 133 to the BD sensor 121. When the polygon mirror 133 has six mirror surfaces, the BD sensor 121 detects the laser beam six times while the polygon mirror 133 rotates once. BD is an abbreviation for beam detection. A detection signal output when the BD sensor 121 receives laser light is used to control the writing position of the laser light in the main scanning direction.

  The drive circuit 130 causes the laser unit 107 to emit light during the image period in which the laser light scans the image area on the photosensitive drum 5, and basically turns off the laser unit 107 during other periods. However, the drive circuit 130 forcibly causes the laser unit 107 to emit light even during a period in which the laser light is incident on the BD sensor 121. The drive circuit 130 executes APC (Auto Power Control) for adjusting the light emission amount during the period in which the laser unit 107 is forced to emit light. The required light emission amount (exposure amount) differs depending on the degree of wear of the photosensitive drum 5. Further, when the temperature of the laser unit 107 rises, the drive current for obtaining the required light emission amount also changes. For this reason, the drive circuit 130 adjusts the drive current in accordance with the amount of laser light received by the photodiode PD.

[Drive circuit]
As shown in FIG. 3, the drive circuit 130 is a circuit including adjustment means for adjusting the light emission amount of the laser unit 107. The drive circuit 130 has an APC unit 150. The APC unit 150 adjusts the drive current supplied to the light source so that the level of the signal output from the photodiode PD becomes a level corresponding to the control value input to the drive circuit 130. A laser unit 107, an engine controller 122, and a video controller 123 are connected to the drive circuit 130. The engine controller 122 includes a CPU 301, a RAM 302, and an EEPROM 303, and controls each part of the image forming apparatus 50 in addition to the drive circuit 130. The EEPROM is an example of a non-volatile memory, and other memories may be adopted. The engine controller 122 controls the video controller 123 that outputs a VIDEO signal to the drive circuit 130. The VIDEO signal is a so-called image signal. The video controller 123 generates a VIDEO signal based on print data sent from an external device such as an image reader or a host computer.

  The conversion circuit 140 is a circuit that converts the PWM signal into a reference voltage Vref and sets it in the APC unit 150. The CPU 301 generates and outputs a PWM signal with a duty that gives a light emission amount corresponding to the degree of consumption (sensitivity) of the photosensitive drum 5. The comparator 101 compares the detection voltage Vm corresponding to the current Im flowing through the photodiode PD in the APC with the reference voltage Vref, and outputs the comparison result to the sample hold circuit 103. The variable resistor 102 is a resistor that converts the current Im into a detection voltage Vm. The resistance value of the variable resistor 102 is set during the manufacturing process. A hold capacitor 104 is connected to the sample hold circuit 103. When the APC is completed, the CPU 301 outputs an SH signal. When the SH signal is input, the sample hold circuit 103 causes the hold capacitor 104 to hold the comparison result. As a result, a voltage for achieving the drive current Idrv determined by the APC is held in the hold capacitor 104. The voltage held by the hold capacitor 104 is input to the positive terminal (non-inverting input terminal) of the operational amplifier 105. A resistor 110 for setting a switching current and an emitter terminal of the transistor 106 are connected to the negative terminal (inverting input terminal) of the operational amplifier 105. The output of the operational amplifier 105 is input to the base terminal of the transistor 106. The collector terminal of the transistor 106 is connected to the switching circuit 108. The driving current Idrv corresponding to the output voltage of the sample hold circuit 103 is determined by the operational amplifier 105, the transistor 106 and the resistor 110. The switching circuit 108 supplies the drive current Idrv to the laser diode LD.

  The OR circuit 124 outputs an output signal Data, which is a calculation result of the Ldrv signal output from the engine controller 122 and the VIDEO signal output from the video controller 123, to the switching circuit 108. The Ldrv signal is a signal for forcibly causing the laser diode LD to emit light. The VIDEO signal is output to the OR circuit 124 via the buffer 125. The CPU 301 controls the buffer 125 by outputting a Venb signal. For example, the CPU 301 starts outputting the VIDEO signal from the buffer 125 by outputting the Venb signal when the writing timing in the main scanning direction comes. The writing timing is the timing at which the laser diode LD starts to emit light.

[APC]
As described above, the CPU 301 forcibly causes the laser diode LD to emit light during the non-image period, and determines the drive current Idrv for setting the light amount of the laser light applied to the surface of the photosensitive drum 5 as the target light amount. The CPU 301 outputs an Ldrv signal to cause the laser diode LD to emit light. The CPU 301 outputs a PWM signal corresponding to the degree of wear of the photosensitive drum 5. The comparator 101 outputs a comparison result between the voltage Vm and the reference voltage Vref. If the light amount is smaller than the target light amount, the drive current Idrv is increased, and if the light amount is larger than the target light amount, the drive current Idrv is reduced. When the non-image period ends, the CPU 301 outputs an SH signal to determine the drive current Idrv. In this way, the light quantity of the laser unit 107 is maintained at the target light quantity.

[Light intensity adjustment process]
As described with respect to the variable resistor 102, the laser light amount adjustment process on the surface of the photosensitive drum 5 is performed in the manufacturing / assembly process of the exposure apparatus 9. In the light amount adjustment step, the exposure device 9 is arranged on a dedicated jig. The jig has a light receiving element. The exposure device 9 is fixed to a jig so that the light receiving element is positioned at a position h0 corresponding to an image height 0 of the photosensitive drum 5. That is, the light receiving element receives a laser beam having the same light amount as the laser beam irradiated on the surface of the photosensitive drum 5.

Adjustment of Variable Resistor As shown in FIG. 4, the duty of the PWM signal correlates with the amount of light on the surface of the photosensitive drum 5. In FIG. 4, the vertical axis represents the light emission luminance of the laser diode LD, and the horizontal axis represents the duty.

  In the light amount adjustment step, the CPU 301 sets the duty of the PWM signal to 100% and causes the drive circuit 130 to execute APC. The jig measures the amount of laser light incident on the light receiving element. The adjuster or the jig adjusts the resistance value of the variable resistor 112 so that the light amount becomes 250 [μW]. 250 [μW] is the maximum amount of light that can be irradiated onto the surface of the photosensitive drum 5.

Acquisition of data indicating the relationship between duty and light quantity As shown in FIG. 4, the duty of the PWM signal and the light quantity on the surface of the photosensitive drum 5 are correlated. If there is data indicating this correlation, the CPU 301 can control the light amount on the surface of the photosensitive drum 5 to the target light amount by changing the duty with reference to the data.

As shown in FIG. 5, S500 is a data acquisition process and is included in the manufacturing / assembly process of the exposure apparatus 9. The data to be acquired is a pair of duty and light quantity. Here, two or more pairs are acquired. S510 is a data writing process, and is included in the manufacturing and assembling process of the image forming apparatus 50. S500 includes S501 to S505.
In S501, the CPU 301 sets the duty of the PWM signal to the i-th duty (eg, 30%, 90%).
In step S502, the CPU 301 causes the driving circuit 130 to execute APC.
In step S503, the CPU 301 causes the jig to measure the i-th light amount corresponding to the i-th duty. i is an integer from 1 to N. N indicates the number of data pairs to be acquired.
In step S <b> 504, the CPU 301 determines whether the light quantity measurement count i has reached N (example: 2). If the light quantity measurement count i has not reached N, the CPU 301 adds 1 to i and returns to S501. In this way, N pieces of data are acquired. For example, 225 [μW] is obtained as the light amount for 90% duty. Further, 70 [μW] is obtained as the light quantity for the duty of 30%. If the light quantity measurement count i has reached N times, the CPU 301 advances to S505.
In step S505, the CPU 301 controls the jig and causes data to be written on the recording medium. For example, the jig has a bar code printer, and a bar code indicating a duty (30%, 90%) and a corresponding light quantity (70 [μW], 225 [μW]) is recorded on the bar code printer. To print. The recording medium may be called a bar code label. The bar code label is attached to the exposure device 9. Further, the barcode of this embodiment also includes information indicating the process speed corresponding to the acquired data. The process speed here is a value related to the driving speed of a member for forming a toner image. For example, it is a value corresponding to the peripheral speed of the photosensitive drum and the rotational speed (scanning speed) of the polygon mirror 133.

The exposure device 9 to which the barcode label is attached is transported to, for example, a factory where the image forming apparatus 50 is assembled. Here, S510 which is a data writing process is executed. S510 includes S511 and S512.
In step S511, the CPU 301 reads data and process speed from the recording medium provided in the exposure apparatus 9. For example, the CPU 301 obtains data and process speed by causing a bar code reader (not shown) connected to the CPU 301 to read a bar code label attached to the exposure apparatus 9.
In step S <b> 512, the CPU 301 writes data and process speed to the EEPROM 303.

[Duty setting method]
Here, a case where the process speed of the image forming apparatus 50 and the process speed of the data written in the EEPROM 303 coincide with each other will be described.

  As described above, the duty of the PWM signal corresponds to the amount of laser light. The CPU 301 manages the degree of wear (such as the number of image formations) of the photosensitive drum 5 and calculates the necessary light amount from the degree of wear. The EEPROM 303 may hold a function for converting the degree of wear to the required light amount.

  The CPU 301 refers to the data stored in the EEPROM 303 and determines the duty corresponding to the required light amount. The CPU 301 executes linear linear interpolation using two points of data such as (90%, 225 [μW]) and (30%, 70 [μW]), and calculates a duty corresponding to 100 [μW]. For this purpose, first, the CPU 301 calculates a slope (eg, 2.583) and an intercept (eg, -7.5) of a linear function indicating the relationship between the duty and the light quantity. The slope and intercept may be stored in the EEPROM 303 instead of the above data. Further, the CPU 301 calculates the duty by the following equation.

Duty = (100 [μW] +7.5 [μW]) / 2.583
= 41.6% (1)
In this embodiment, two data pairs are used because the relationship between the duty and the light quantity is approximated by a linear function. If the relationship between duty and light quantity is approximated by a higher order function, more data pairs will be required. The recording medium for storing the data pair is not limited to the bar code label, and may be a memory.

[Measurement of main scanning position]
The timing for writing out the latent image in the main scanning direction must be adjusted according to the individual difference of the exposure device 9. Therefore, this adjustment value is acquired in the assembly process. As shown in FIG. 6, step S <b> 600 is a data acquisition process performed in the manufacturing / assembly process of the exposure apparatus 9. S600 includes S601 to S604. Step S610 is a data writing process performed in the manufacturing / assembly process of the image forming apparatus 50. S610 includes S611 and S612. Note that the jig for acquiring the write timing data may be the same as the above jig. Also in this case, the exposure apparatus 9 is fixed to the jig so that the light receiving element is positioned at the position h0.

In this embodiment, the time Tc from the timing when the BD sensor 121 outputs the detection signal to the timing when the light receiving element arranged on the jig outputs the detection signal is measured. The design ideal value T0 exists at this time Tc. Therefore, the difference between the ideal value T0 and the measured time Tc is the adjustment value Tc ′.
In step S601, the CPU 301 activates the exposure apparatus 9 to execute APC.
In step S602, the CPU 301 measures time Tc. For example, the CPU 301 starts a counter when the BD sensor 121 outputs a detection signal. When the light receiving element arranged on the jig outputs a detection signal, the CPU 301 stops the counter and acquires the count value. This count value is the time Tc.
In step S603, the CPU 301 calculates an adjustment value Tc ′. For example, the CPU 301 calculates the adjustment value Tc ′ by subtracting the time Tc from the ideal value T0.
In S604, the CPU 301 writes the adjustment value Tc ′ and the process speed on the recording medium through the jig. For example, the adjustment value Tc ′ may also be recorded on the barcode label described above. The bar code label is attached to the exposure device 9.

The exposure device 9 to which the bar code label is attached is conveyed to the assembly process of the image forming apparatus 50. Here, S610, which is a data writing process, is executed.
In step S611, the CPU 301 reads data indicating the adjustment value Tc ′ and the process speed from the recording medium provided in the exposure apparatus 9. For example, the CPU 301 obtains data and process speed by causing a bar code reader (not shown) connected to the CPU 301 to read a bar code label attached to the exposure apparatus 9.
In step S <b> 612, the CPU 301 writes the data and process speed to the EEPROM 303.

[Main scan position correction]
Here, a case where the process speed of the image forming apparatus 50 and the process speed of the data written in the EEPROM 303 coincide with each other will be described.

  The video controller 123 outputs a VIDEO signal in synchronization with the BD signal. The BD signal is a detection signal that is output when the BD sensor 121 receives light. The video controller 123 determines the output timing of the VIDEO signal based on the size and margin information of the sheet P. Here, the video controller 123 corrects the output timing with the adjustment value Tc ′ written in the EEPROM 303, and outputs a VIDEO signal according to the corrected output timing.

[When the process speed of the image forming device and the process speed associated with the data are different]
With the common use of the exposure apparatus 9, it has been assumed that the exposure apparatus 9 having the same specification is mounted on a plurality of image forming apparatuses 50 having different process speeds. Therefore, the exposure apparatus 9 must hold the above data for each of a plurality of process speeds. In other words, dedicated data is required for each process speed. When the process speed is different, the rotational speed of the polygon mirror 133 is also different. For example, when the number of rotations of the polygon mirror 133 increases, the time for the laser light to expose a certain area on the photosensitive drum 5 is shortened. That is, the exposure amount [μJ / cm 2] decreases. Furthermore, since the above-described time Tc is also shortened, the adjustment value Tc ′ cannot be applied as it is. However, if data is acquired for all of the plurality of process speeds, the number of man-hours increases. In addition, the capacity of the memory increases and the manufacturing cost increases.

  Therefore, in this embodiment, a device in the case where the process speed of the image forming apparatus and the process speed associated with the data stored in the EEPROM 303 are different will be described. In particular, in this embodiment, data for other process speeds is obtained based on data for specific process speeds. In other words, in the present embodiment, data for a specific process speed is stored in the EEPROM 303, and other process speed data is not stored in the EEPROM 303. Only data for a specific process speed is acquired in the assembly process, and data for other process speeds is not acquired in the assembly process. Thereby, an adjustment method of the exposure apparatus 9 that is advantageous with respect to the man-hour and the manufacturing cost is provided.

  In this embodiment, it is assumed that the process speed of the first image forming apparatus 50 is 100 [mm / sec] and the process speed of the second image forming apparatus 50 is 150 [mm / sec]. The first image forming apparatus 50 and the second image forming apparatus 50 are each equipped with an exposure device 9 having a common specification. Data for a process speed of 150 [mm / sec] is acquired and recorded on a recording medium of the exposure apparatus 9.

Flowchart FIG. 7 shows light amount adjustment and write timing adjustment processing executed by the CPU 301.
In step S <b> 701, the CPU 301 reads the light amount data, the adjustment value Tc ′, and the process speed associated therewith from the EEPROM 303.
In step S <b> 702, the CPU 301 determines whether the process speed of the image forming apparatus 50 matches the process speed read from the EEPROM 303. If the process speed set in the image forming apparatus 50 is 150 [mm / sec], it matches the process speed stored in the EEPROM 303. If the two match, the CPU 301 advances to S703. On the other hand, if the process speed set in the image forming apparatus 50 is 100 [mm / sec], it does not match the process speed stored in the EEPROM 303. If the two do not match, the CPU 301 advances to S704.
In step S <b> 703, the CPU 301 uses the data read from the EEPROM 303 to adjust the light amount of the exposure apparatus 9 and the writing start timing.
In step S <b> 704, the CPU 301 corrects the data read from the EEPROM 303 according to the process speed set in the image forming apparatus 50.
In step S <b> 705, the CPU 301 adjusts the light amount of the exposure apparatus 9 and the writing start timing using the corrected data.

Data Correction Method FIG. 8 shows the relationship between the exposure amount [μJ / cm 2] on the surface of the photosensitive drum 5 and the duty. As shown in FIG. 8, this relationship changes depending on the process speed. When the process speed is 150 [mm / sec], the duty with which an exposure amount of 0.5 [μJ / cm 2] is obtained is 90%. On the other hand, when the process speed is 100 [mm / sec], the duty with which an exposure amount of 0.5 [μJ / cm 2] is obtained is 60%. That is, the ratio between the two process speeds and the ratio between the two duties are the same. The CPU 301 may correct the data held in the EEPROM 303 by multiplying the data by a correction coefficient corresponding to the ratio of the two process speeds. Further, the CPU 301 may correct the duty determined based on the data held in the EEPROM 303 according to the process speed. This is because the results are the same.

  The time Tc is inversely proportional to the process speed. Therefore, the CPU 301 may correct the adjustment value Tc ′ by multiplying the adjustment value Tc ′ by a correction coefficient corresponding to the reciprocal of the ratio of the two process speeds.

<Summary>
The function of the CPU 301 will be described with reference to FIGS. FIG. 9 shows that the duty and the write start timing are determined using the data corrected according to the process speed. FIG. 10 shows a modification thereof, which shows that the duty determined using data and the write start timing are corrected according to the process speed. Both give the same result.

  As shown in FIGS. 9 and 10, the EEPROM 303 stores first data (example: data 932) indicating the relationship between the light amount of the light source (example: emission luminance) and the control value (example: duty) input to the drive circuit 130. It is an example of the holding means to hold | maintain. The data 932 is data for a specific process speed, and may or may not match the process speed of the image forming apparatus 50. The data 932 is, for example, a data pair having light emission luminance [mW] and duty [%]. The light amount determination unit 901 determines a target light amount (eg, light emission luminance) of the laser unit 107 according to the degree of wear 931 of the photosensitive drum 5 and outputs the target light amount to the duty determination unit 902. The degree of wear 931 of the photosensitive drum 5 is an example, and the target light amount may be determined based on other parameters. The correction unit 904a corrects the data 932 according to the process speed, and supplies the corrected data 932 to the duty determination unit 902. The duty determining unit 902 determines a duty corresponding to the target light amount based on the corrected data 932. The correction unit 904a functions as a correction unit that corrects data held in the EEPROM 303 in accordance with the process speed. The duty determination unit 902 is an example of a first determination unit that determines a control value input to the drive circuit 130 to control the light amount of the light source to a predetermined light amount based on the corrected data 932. The signal generation unit 903 a generates a PWM signal having the duty determined by the duty determination unit 902 and outputs the PWM signal to the drive circuit 130. As described above, the CPU 301 functions as a control unit that obtains a control value input to the driving unit based on the process speed and data regarding the driving speed of a member for forming a toner image or an electrostatic latent image. Therefore, according to the present embodiment, if at least one process speed data 932 is acquired and held in the EEPROM 303, other process speed data is obtained by calculation. Therefore, an image forming apparatus advantageous in terms of man-hours and manufacturing costs is provided. Here, as an example, the control by the CPU 301 as the control means in the engine controller 122 has been described. However, the present invention is not limited to this, and when the exposure apparatus 9 includes a CPU as a control means, the CPU of the exposure apparatus 9 can also perform control.

  The speed determination unit 905 determines whether the process speed of the image forming apparatus 50 matches the process speed stored in the speed information 933. The speed determination unit 905 outputs the determination result to the correction units 904a and 904b. The correction unit 904a is an example of a first correction unit that corrects the data 932 according to the process speed, which is the toner image formation speed, and outputs the corrected data 932 to the duty determination unit 902. In FIG. 9, the process speed associated with the data 932 and the adjustment value Tc ′ is stored in the speed information 933. If the process speed of the image forming apparatus 50 matches the process speed stored in the speed information 933, the correction units 904a and 904b do not have to perform correction. The correction unit 904a supplies the data 932 to the duty determination unit 902 without correcting it. The correction unit 904b supplies the adjustment value Tc ′ to the timing determination unit 906 without correcting it.

  As shown in FIG. 9, the EEPROM 303 holds speed information 933 indicating the process speed associated with the data 932. The correction unit 904a may correct the data 932 using a correction coefficient corresponding to the ratio between the process speed of the image forming apparatus 50 and the process speed associated with the data 932.

  As shown in FIG. 4, the light amount of the light source may indicate the luminance of light on the surface of the photoreceptor. Further, the light amount of the light source in the present embodiment indicates, for example, the luminance of light at the position h0 where the image height is 0 on the surface of the photoconductor. The data 932 includes a pair of the first control value (example: 90%) and the first light quantity (example: 250), and a pair of the second control value (example: 30) and the second light quantity (example: 70). May be included. In this case, the correction unit 904a corrects the first control value and the second control value included in the data 932 according to the process speed. The duty determination unit 902 obtains a function representing the relationship between the control value and the light amount of the light source using the corrected data 932, and determines a control value corresponding to the predetermined light amount using the function.

  On the other hand, the data 932 may include the slope and intercept of a linear function representing the relationship between the control value and the light amount of the light source. In this case, the correction unit 904a corrects the inclination and intercept according to the process speed. The duty determination unit 902 determines a control value corresponding to the predetermined light amount using a function defined by the corrected inclination and intercept.

  The photodiode PD is an example of a light receiving unit that receives light output from the light source. The APC unit 150 is an example of an adjustment unit that adjusts the light amount of the light source based on a signal output from the photodiode PD. The APC unit 150 adjusts the drive current Idrv supplied to the light source so that the level of the signal output from the light receiving means becomes a level corresponding to the control value input to the drive circuit 130.

  The EEPROM 303 is a holding unit that holds an adjustment value Tc ′ that is second data for adjusting the timing at which the light source starts to emit light. As shown in FIG. 9, the adjustment value Tc ′ may be corrected by the correction unit 904b according to the process speed. That is, the correction unit 904b is an example of a correction unit that corrects data (eg, adjustment value Tc ′) according to the process speed. The timing determination unit 906 is an example of a determination unit that determines the timing at which an image signal is output to the drive circuit 130 according to the data corrected by the correction unit 904b. The signal generation unit 903b outputs the Venb signal at the timing determined by the correction unit 904b. The buffer 125 starts outputting the VIDEO signal when the Venb signal is input. Thus, the CPU 301 obtains the timing at which the light source starts to emit light based on the process speed relating to the driving speed of the member for forming the toner image (electrostatic latent image) or the resolution and data of the toner image (electrostatic latent image). It functions as a control means. According to the present embodiment, if at least one process speed adjustment value Tc 'is acquired and held in the EEPROM 303, another process speed adjustment value Tc' is obtained by calculation. Therefore, an image forming apparatus and an exposure apparatus that are advantageous with respect to man-hours and manufacturing costs are provided. Here, as an example, the control by the CPU 301 as the control means in the engine controller 122 has been described. However, the present invention is not limited to this, and when the exposure apparatus 9 includes a CPU as a control means, the CPU of the exposure apparatus 9 can also perform control.

  The adjustment value Tc ′ is data for correcting the writing position of the latent image in the scanning direction of the light output from the exposure device 9. The correction unit 904 b may correct the adjustment value Tc ′ using a correction coefficient corresponding to the ratio between the process speed of the image forming apparatus 50 and the process speed associated with the adjustment value Tc ′ stored in the EEPROM 303. .

  FIG. 10 shows a modification of this embodiment. In FIG. 10, the description of matters common to FIG. 9 is omitted. The correction method shown in FIG. 9 corresponds to pre-correction, and the correction method shown in FIG. 10 corresponds to post-correction. The duty determination unit 902 is a first determination unit that determines a control value input to the drive circuit 130 to control the light amount of the light source to a predetermined light amount based on data (eg, wear level 931) held in the EEPROM 303. It is an example. The correction unit 904a is an example of a first correction unit that corrects the control value (eg, duty) determined by the duty determination unit 902 according to the process speed and outputs the correction value to the drive circuit 130. The signal generation unit 903a generates a PWM signal with the duty corrected by the correction unit 904a and outputs the PWM signal to the drive circuit 130. Note that the speed determination unit 905 may determine that the process speed of the image forming apparatus 50 matches the process speed stored in the speed information 933. In this case, the correction unit 904a may supply the control value determined by the duty determination unit 902 to the signal generation unit 903a without correcting the control value.

  The duty determining unit 902 obtains a function representing the relationship between the control value and the light amount of the light source using the data 932, and determines a control value corresponding to the predetermined light amount using the function. The correction unit 904a corrects the control value determined by the duty determination unit 902 according to the process speed. The data 932 may include the slope and intercept of a linear function representing the relationship between the control value and the light amount of the light source. In this case, the duty determination unit 902 obtains a function representing the relationship between the control value and the light amount of the light source using the data 932, and determines a control value corresponding to the predetermined light amount using the function. The function may be a linear function defined by the corrected slope and intercept. The correction unit 904a may correct the control value using a coefficient corresponding to the ratio between the process speed of the image forming apparatus 50 and the process speed associated with the data 932.

  In FIG. 10, the timing determination unit 906 is an example of a second determination unit that determines the timing at which the image signal is output to the drive unit at a timing adjusted according to data (eg, adjustment value Tc ′) held in the holding unit. It is. The correction unit 904b is an example of a second correction unit that corrects the timing according to the process speed. The correcting unit 904b corrects the timing determined based on the adjustment value Tc ′. The signal generation unit 903b outputs the Venb signal at the timing corrected by the correction unit 904b. The correction unit 904b may correct the timing using a correction coefficient corresponding to the ratio between the process speed of the image forming apparatus 50 and the process speed associated with the adjustment value Tc ′. When the process speed of the image forming apparatus 50 matches the process speed associated with the adjustment value Tc ′, the correction unit 904 b does not correct the timing.

  In this embodiment, there are two types of data stored in the EEPROM in the assembly process: measured data and process speed, but the same correction can be made only with measured data. In that case, an arithmetic processing method for the data measured by the correction unit 904 of the CPU 301 may be provided for each process speed of the image forming apparatus 50.

  In addition, the electrostatic latent image writing timing in the main scanning direction has a correlation with the resolution of the image. Specifically, the time Tc is inversely proportional to the resolution. Therefore, the CPU 301 may correct the adjustment value Tc ′ by multiplying the adjustment value Tc ′ by a correction coefficient corresponding to the reciprocal of the ratio of the two resolutions.

  DESCRIPTION OF SYMBOLS 50 ... Image forming apparatus, 7 ... Charger, 9 ... Exposure apparatus, 8 ... Developing device, 3 ... Intermediate transfer belt, 14 ... Fixing device, 130 ... Driving circuit, 303 ... EEPROM, 301 ... CPU

Claims (20)

A photoreceptor,
Charging means for charging the photoreceptor;
Exposure means for exposing the photosensitive member to form an electrostatic latent image, the specification and the second process speed of a first image forming apparatus that forms an image with a first parameter that is a first process speed or a first resolution. Or an exposure unit having a common specification satisfying the specification of the second image forming apparatus that forms an image with the second parameter being the second resolution ;
Developing means for developing the electrostatic latent image to form a toner image;
Driving means for driving a light source of the exposure means;
The data indicating the relationship between the light quantity of the light source and the control value input to the driving means, the data acquired in the assembly process for the first process speed related to the driving speed of the member for forming the toner image Holding means not holding the data for a second process speed different from the first process speed;
When the process speed related to the driving speed of the member for forming the toner image is the first process speed by mounting the exposure unit on the first image forming apparatus, the data held in the holding unit The control value input to the driving unit is obtained based on the above, and when the process speed is the second process speed because the exposure unit is mounted on the second image forming apparatus, the control unit holds the control value. Control means for correcting the data about the first process speed, and obtaining a control value input to the driving means based on the corrected data,
The image forming apparatus, wherein the driving unit drives the light source based on a control value obtained by the control unit.   The image forming apparatus according to claim 1, wherein the member is the photosensitive member, and the process speed is a peripheral speed of the photosensitive member.   The image forming apparatus according to claim 1, wherein the member is the exposure unit, and the process speed is a scanning speed of the exposure unit. The control means includes
When the process speed is the second process speed, correction means for correcting the data about the first process speed held in the holding means;
When the process speed is the second process speed, the control value input to the drive unit to control the light amount of the light source to a predetermined light amount is determined based on the data corrected by the correction unit. 4. The image forming apparatus according to claim 1, further comprising a determining unit that inputs the driving unit. 5. The holding means holds speed information indicating a process speed associated with the data,
5. The correction unit according to claim 4, wherein the correction unit corrects the data using a coefficient corresponding to a ratio between a process speed of the image forming apparatus and a process speed associated with the data. The image forming apparatus described in 1. The holding means holds speed information indicating a process speed associated with the data,
The correction means supplies the data to the determination means without correction when the process speed of the image forming apparatus matches the process speed associated with the data. The image forming apparatus according to claim 4.   The image forming apparatus according to claim 1, wherein the light amount of the light source indicates a luminance of light on a surface of the photoconductor.   The image forming apparatus according to claim 7, wherein the light amount of the light source indicates a luminance of light at a position where the image height is 0 on the surface of the photoconductor. The data includes a pair of a first control value and a first light amount, and a pair of a second control value and a second light amount,
The correction means corrects the first control value and the second control value included in the data according to the process speed,
The determining means obtains a function representing a relationship between a control value and a light amount of the light source using the corrected data, and determines a control value corresponding to the predetermined light amount using the function. The image forming apparatus according to claim 4. The data includes a slope and intercept of a linear function representing the relationship between the control value and the light amount of the light source,
The correction means corrects the inclination and the intercept according to the process speed,
The determining means obtains a function representing a relationship between a control value and a light amount of the light source using the corrected data, and determines a control value corresponding to the predetermined light amount using the function. The image forming apparatus according to claim 4.   The image forming apparatus according to claim 4, wherein the determining unit determines the predetermined light amount according to a degree of wear of the photosensitive member. The exposure means includes a light receiving means for receiving light output from the light source,
The driving means includes an adjusting means for adjusting the light amount of the light source based on a signal output from the light receiving means,
The adjusting unit adjusts a driving current supplied to the light source so that a level of a signal output from the light receiving unit becomes a level corresponding to a control value input to the driving unit. The image forming apparatus according to any one of 1 to 11. A photoreceptor,
Charging means for charging the photoreceptor;
Specification of a first image forming apparatus that forms an electrostatic latent image by exposing the photoconductor in accordance with an image signal, and forms an image with a first parameter that is a first process speed or a first resolution. And an exposure means having a common specification that satisfies the specifications of the second image forming apparatus that forms an image with the second parameter that is the second process speed or the second resolution ,
Developing means for developing the electrostatic latent image to form a toner image;
Driving means for driving a light source of the exposure means;
Assembling step for the first parameter which is data for adjusting the timing at which the light source starts to emit light and which is the first process speed related to the driving speed of the member for forming the toner image or the first resolution of the toner image Holding means for holding the data acquired in step, and not holding the data for the second parameter different from the first parameter;
When the exposure speed is mounted on the first image forming apparatus and a parameter that is a process speed relating to a driving speed of a member for forming the toner image or a resolution of the toner image is the first parameter, Based on the data about the first parameter held in the holding unit, a timing at which the light source starts to emit light is obtained, and the exposure unit is mounted on the second image forming apparatus, so that the parameter is changed to the first parameter. A control unit that corrects the data for the first parameter based on the parameter when it is a two-parameter, and determines the timing at which the light source starts to emit light based on the corrected data;
The image forming apparatus, wherein the driving unit drives the light source based on a timing of starting light emission obtained by the control unit. The control means includes
When the parameter is the second parameter, correction means for correcting the data about the first parameter held in the holding means;
And determining means for determining a timing for outputting the image signal to the driving means, which is a timing for starting the light emission, according to the data corrected by the correcting means when the parameter is the second parameter. The image forming apparatus according to claim 13.   15. The image forming apparatus according to claim 13, wherein the data is data for adjusting a writing position of a latent image in a scanning direction of light output from the exposure unit. The parameter is process speed,
The holding means holds speed information indicating a process speed associated with the data,
15. The correction unit corrects the data by using a coefficient corresponding to a ratio between a process speed of the image forming apparatus and a process speed associated with the data. The image forming apparatus described in 1. The parameter is process speed,
The holding means holds speed information indicating a process speed associated with the data,
15. The correction unit according to claim 14, wherein the correction unit does not correct the timing when a process speed of the image forming apparatus matches a process speed associated with the data. Image forming apparatus. The data held in the holding means is data indicating a relationship between the light amount of the light source and a control value input to the driving means,
The control means obtains a control value input to the drive means based on the process speed related to the drive speed of the member for forming the toner image and the data,
The image forming apparatus according to claim 14, wherein the driving unit drives the light source based on a control value obtained by the control unit. Specifications of the first image forming apparatus that forms an image with a first parameter that is a first process speed or first resolution for exposing the photoreceptor to form an electrostatic latent image, and a second process speed or second resolution. An exposure apparatus having a common specification that satisfies the specifications of a second image forming apparatus that forms an image with a second parameter ,
A light source that outputs light for forming an electrostatic latent image;
Driving means for driving the light source;
Data indicating the relationship between the light quantity of the light source and the control value input to the driving means, acquired in the assembly process for the first process speed related to the driving speed of the member for forming the electrostatic latent image Holding means for holding the data and not holding the data for a second process speed different from the first process speed;
When the exposure apparatus is mounted on the first image forming apparatus and the process speed related to the driving speed of the member for forming the electrostatic latent image is the first process speed, the exposure apparatus holds the holding means. A control value input to the driving means based on the data stored in the second image forming apparatus, and when the process speed is the second process speed, the holding means holds the control value. Control means for correcting the data about the first process speed being performed and obtaining a control value input to the drive means based on the corrected data, the drive means comprising the control means An exposure apparatus that drives the light source based on a control value obtained by the above. Specifications of the first image forming apparatus that forms an image with a first parameter that is a first process speed or first resolution for exposing the photoreceptor to form an electrostatic latent image, and a second process speed or second resolution. An exposure apparatus having a common specification that satisfies the specifications of a second image forming apparatus that forms an image with a second parameter ,
A light source that outputs light for forming an electrostatic latent image;
Driving means for driving the light source;
Data for adjusting the timing at which the light source starts to emit light, which is a first process speed relating to a driving speed of a member for forming the electrostatic latent image or a first resolution of the electrostatic latent image. Holding means for holding data acquired in the assembly step for parameters, and not holding the data for the second parameter different from the first parameter;
When the exposure apparatus is mounted on the first image forming apparatus , a parameter that is a process speed relating to a driving speed of a member for forming the electrostatic latent image or a resolution of the electrostatic latent image is the first parameter. In some cases, the timing at which the light source starts to emit light is obtained based on the data about the first parameter held in the holding unit, and the exposure apparatus is mounted on the second image forming apparatus, thereby Control means for correcting the data for the first parameter based on the parameter when the parameter is the second parameter, and determining timing for starting the light emission of the light source based on the corrected data; ,
The exposure apparatus characterized in that the driving means drives the light source based on the timing of starting the light emission obtained by the control means.

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