JP2023038049A - Image formation device, light-emission control method and program - Google Patents

Abstract

To provide an image formation device, a light-emission control method and a program which correct inclination for each light source at each main scanning position, and can reduce occurrence of irregular pitches.SOLUTION: An image formation device includes: an image formation part 10 for scanning an image carrier (photoreceptor 200) with a plurality of rays of light emitted from a plurality of light sources in a main scanning direction, and forming an image; a modulation part (control part 20) for modulating frequencies of each of the light sources according to main scanning intervals at a plurality of main scanning positions; a light-emission control part (control part 20) for controlling light-emission timings of each of the light sources on the basis of a modulation result; and a storage part 30 for storing main scanning intervals measured by a first measurement part for measuring the main scanning intervals, and a second measurement part arranged corresponding to the plurality of main scanning positions in a manufacturing process. The modulation part modulates frequencies of each of the light sources on the basis of a frequency modulation rate calculated based on a main scanning interval stored in the storage part 30 and a main scanning interval measured by the first measurement part.SELECTED DRAWING: Figure 2

Description

The present invention relates to an image forming apparatus, light emission control method, and program.

2. Description of the Related Art Conventionally, image forming apparatuses such as laser printers and digital copiers are equipped with an image writing section that scans a photosensitive member using a semiconductor laser emitted from a light source.

In recent years, there has been a demand for high-speed, high-density image recording in image forming apparatuses. Formation is performed, and the image formation for one page is performed by repeating the above image formation in the sub-scanning direction. In a configuration using a plurality of light sources, an increase in ambient temperature or the like may cause each light source to shift from its design position in the main scanning direction, and the inclination (main scanning interval) of each light source may change. As a result, pitch unevenness occurs in the output image.

Therefore, a configuration for correcting the main scanning interval (main scanning pitch) by adjusting the light emission start timing for each light source has been disclosed (see, for example, Patent Document 1).

JP 2018-105895 A

However, even in the configuration described in Patent Document 1, the inclination of each light source at each main scanning position (each position in the main scanning direction) on the photoreceptor changes depending on the lens accuracy and mechanical adjustment accuracy of the fθ lens. The main scanning magnification changes every time, and the effect of the main scanning pitch correction is lost, resulting in pitch unevenness in the output image.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus, a light emission control method, and a program capable of correcting the inclination of each light source at each main scanning position to reduce the occurrence of pitch unevenness.

The invention according to claim 1 was made to achieve the above object,
In an image forming apparatus,
an image forming unit that scans an image carrier in a main scanning direction with a plurality of light beams emitted from a plurality of light sources according to image data to form an image;
a modulation unit that frequency-modulates each light source according to a main scanning interval at a plurality of main scanning positions of the plurality of light beams;
a light emission control unit that controls the light emission timing of each light source based on the result of modulation by the modulation unit;
a first measuring unit that measures the main scanning interval;
a storage unit that stores the main scanning intervals measured by a second measuring unit arranged to correspond to the plurality of main scanning positions in the production process;
with
The modulation unit calculates the frequency modulation rate of each light source based on the main scanning interval stored in the storage unit and the main scanning interval measured by the first measurement unit, and based on the calculated frequency modulation rate and frequency-modulating each light source.

The invention according to claim 2 is the image forming apparatus according to claim 1,
The first measurement unit is arranged near an irradiation start position and an irradiation end position outside the image area.

The invention according to claim 3 is the image forming apparatus according to claim 1 or 2,
Equipped with a detection unit that detects environmental changes in the device,
The modulating unit modulates each of the light sources based on the main scanning interval stored in the storage unit and the main scanning interval measured by the first measuring unit when the detecting unit detects an environmental change of a predetermined value or more. is calculated, and each light source is frequency-modulated based on the calculated frequency modulation rate.

The invention according to claim 4 is the image forming apparatus according to any one of claims 1 to 3,
an image forming control unit that causes the image forming unit to form a chart for calculating the main scanning interval;
an acquisition unit that acquires density information of the chart formed by the image forming unit;
a calculation unit that calculates the main scanning interval based on the density information;
with
The modulating unit adjusts the main scanning interval stored in the storage unit and the main scanning interval measured by the first measuring unit when a change in the main scanning interval is detected based on the calculation result of the calculating unit. The frequency modulation rate of each light source is calculated based on the calculated frequency modulation rate, and each light source is frequency-modulated based on the calculated frequency modulation rate.

The invention according to claim 5 is the image forming apparatus according to any one of claims 1 to 4,
The modulation unit calculates a frequency modulation rate of each light source based on the main scanning interval stored in the storage unit and the main scanning interval measured by the first measurement unit when a predetermined time has elapsed, It is characterized in that each light source is frequency-modulated based on the calculated frequency-modulation rate.

The invention according to claim 6,
an image forming unit that scans an image carrier in a main scanning direction with a plurality of light beams emitted from a plurality of light sources according to image data to form an image; and main scanning of the plurality of light beams at a plurality of main scanning positions An image forming apparatus comprising: a first measuring unit that measures an interval; and a storage unit that stores the main scanning interval measured by a second measuring unit arranged to correspond to the plurality of main scanning positions in a production process. A light emission control method for a device,
a modulation step of frequency-modulating each light source according to a main scanning interval at a plurality of main scanning positions of the plurality of light beams;
a light emission control step of controlling the light emission timing of each of the light sources based on the modulation result of the modulation step;
including
In the modulating step, the frequency modulation rate of each light source is calculated based on the main scanning interval stored in the storage unit and the main scanning interval measured by the first measurement unit, and based on the calculated frequency modulation rate and frequency-modulating each light source.

The invention according to claim 7,
an image forming unit that scans an image carrier in a main scanning direction with a plurality of light beams emitted from a plurality of light sources according to image data to form an image; and main scanning of the plurality of light beams at a plurality of main scanning positions An image forming apparatus comprising: a first measuring unit that measures an interval; and a storage unit that stores the main scanning interval measured by a second measuring unit arranged to correspond to the plurality of main scanning positions in a production process. device computer,
a modulation unit that frequency-modulates each light source according to a main scanning interval at a plurality of main scanning positions of the plurality of light beams;
a light emission control unit that controls the light emission timing of each light source based on the result of modulation by the modulation unit;
function as
The modulation unit calculates the frequency modulation rate of each light source based on the main scanning interval stored in the storage unit and the main scanning interval measured by the first measurement unit, and based on the calculated frequency modulation rate and frequency-modulating each light source.

According to the present invention, it is possible to correct the inclination of each light source at each main scanning position and reduce the occurrence of pitch unevenness.

1 is a diagram showing a schematic configuration of an image forming apparatus according to an embodiment; FIG. 3 is a functional block diagram showing the control structure of the image forming apparatus according to the embodiment; FIG. 3 is a diagram showing a schematic configuration of an image writing unit; FIG. FIG. 10 is a diagram showing an example of light emission timing of each light source when printing a straight line at three positions of the leading edge, the center, and the trailing edge of the paper in the main scanning direction. FIG. 10 is a diagram showing an example of how a print position gradually deviates in a case where straight lines are printed at three locations of the leading edge, the center, and the trailing edge of a sheet in the main scanning direction. FIG. 10 is a diagram showing an example of a configuration for measuring the inclination of each light source at a plurality of main scanning positions using photodiodes during the production process; 7 is a diagram showing an example of light reception timing in each photodiode when measuring the inclination of each light source in the configuration of FIG. 6. FIG. FIG. 10 is a diagram showing an example of data before change measured in a production process and data after change measured on an actual machine after starting operation; 4 is a flow chart showing the operation of the image forming apparatus according to the embodiment;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

An image forming apparatus 1000 according to the present embodiment is used as, for example, a laser printer, a digital copier, or the like. As shown in FIGS. It comprises a camera 40 , an operation panel 50 and an environment detection section 60 .

The image forming unit 10 includes a plurality of image writing units 100 provided for each of cyan, magenta, yellow, and black, and photoreceptors (image forming units) such as photoreceptor drums provided corresponding to the image writing units 100 . a carrier 200, a charging unit 210 that charges the photoreceptor 200, and a developing unit 220 that supplies a developer to the photoreceptor 200 irradiated with light to develop an electrostatic latent image into an image formed by the developer. , an intermediate transfer belt 300, a transfer roller 400 for transferring the developer image onto the paper P, and a fixing unit 500 for fixing the developer image transferred by the transfer roller 400 onto the paper P. be.

The image forming unit 10 irradiates (scans) a plurality of laser beams (light beams) emitted from a plurality of light sources 1 (see FIG. 3) on the photoreceptor 200 in the main scanning direction according to image data to form an image. do. Specifically, first, the image forming unit 10 forms a toner image on the photosensitive member 200 exposed to laser light emitted from the image writing unit 100, and transfers the toner image onto the intermediate transfer belt 300. . Next, the image forming unit 10 causes the transfer roller 400 to press the toner image transferred onto the intermediate transfer belt 300 onto the paper P to transfer it, and the fixing unit 500 heats and presses the paper P to form the toner image. is fixed on the paper P. Then, the image forming section 10 carries out the image forming process by conveying the paper P by a paper discharge roller (not shown) or the like and discharging the paper P to a tray (not shown).

As shown in FIG. 3, the image writing unit 100 exposes the photoreceptor 200 charged by the charging unit 210 to the photoreceptor 200 by irradiating the photoreceptor 200 with a laser beam L (electrostatic latent charge on the photoreceptor 200). image). The image writing unit 100 includes a light source 1 that emits a laser beam L, a deflector 2 that deflects the laser beam L emitted from the light source 1, and the laser beam L deflected by the deflector 2 onto the photosensitive member 200. a first reflecting mirror 4 that reflects the laser beam L transmitted through the fθ lens 3 toward the photosensitive member 200; 2 reflecting mirror 5 and a light receiving section 6 for receiving the laser beam L reflected by the second reflecting mirror 5 .

A light source 1 is a laser diode (LD) that emits laser light L. As shown in FIG. A laser beam L emitted from a light source 1 is applied to a deflector 2 . In the example shown in FIG. 3, for convenience of explanation, only one light source 1 is shown. A light source unit 11 is configured by the light source 1 of the above. Note that the light source unit 11 is provided for each color.

The deflector 2 includes a polygon mirror having a polygonal prism shape with mirrored side surfaces, and a motor that applies a rotating force to the polygon mirror to rotate the polygon mirror. The deflector 2 deflects the laser light L emitted from the light source 1 in a direction corresponding to the rotation. Then, the deflector 2 irradiates the peripheral surface of the photosensitive member 200 with the deflected laser light L through the fθ lens 3 . At this time, the deflector 2 irradiates the laser light L at different positions in the longitudinal direction of the photoreceptor 200 according to the rotational position. allows scanning of

The fθ lens 3 converges the laser light L deflected by the deflector 2 onto the photosensitive member 200 to form an image.
The first reflecting mirror 4 reflects the laser beam L transmitted through the fθ lens 3 toward the photosensitive member 200 .

The second reflecting mirror 5 is arranged near the irradiation start position and the irradiation end position outside the image area, reflects a part of the laser light L that has been deflected by the deflector 2 and transmitted through the fθ lens 3, and reflects the reflected laser light. L is made incident on the light receiving portion 6 .
The light receiving unit 6 is arranged near the irradiation start position and the irradiation end position outside the image area, like the second reflection mirror 5 , and detects the laser light L reflected by the second reflection mirror 5 . The light receiving unit 6 includes an SOS substrate 61 arranged near an irradiation start position outside the image area, and an EOS substrate 62 arranged near an irradiation end position outside the image area. Each substrate (SOS substrate 61, EOS substrate 62) is provided with a pair of photodiodes PD11 and PD12. The photodiodes PD11 and PD12 function as a first measurement section of the invention that measures the main scanning interval at each main scanning position.

The control unit 20 is configured with a CPU, a RAM, and the like. The CPU reads out various processing programs stored in a storage device such as the storage unit 30, develops them in the RAM, and centrally controls the operation of each unit of the image forming apparatus 1000 according to the developed programs.
For example, the control unit 20 detects the writing position on the photoreceptor 200 based on the detection signal detected by the light receiving unit 6 that detects the laser light L reflected by the second reflecting mirror 5 arranged near the irradiation end position. timing adjustment, etc.
Further, the control unit 20 frequency-modulates each light source 1 according to the main scanning intervals (tilts) of the plurality of light beams at the plurality of main scanning positions. That is, the control section 20 functions as a modulating section of the present invention.
Also, the control unit 20 controls the light emission timing of each light source 1 based on the modulation result. That is, the control section 20 functions as a light emission control section of the present invention.

The storage unit 30 stores programs that can be read by the control unit 20, files that are used when the programs are executed, and the like. A large-capacity memory such as a hard disk can be used as the storage unit 30 .
For example, the storage unit 30 stores main scanning intervals measured by photodiodes PD1 and PD2 (second measurement unit: see FIG. 6) arranged to correspond to a plurality of main scanning positions in the production process. The storage unit 30 may also store the frequency modulation rate of each light source 1 calculated based on the main scanning interval measured by the photodiodes PD1 and PD2.

The camera 40 acquires density information of the image (chart) formed by the image forming section 10 . That is, the camera 40 functions as an acquisition section of the present invention. A sensor such as a photodiode may be used instead of the camera 40 to irradiate the image formed by the image forming unit 10 with light and receive the reflected light. Concentration information may be acquired.

The operation panel 50 includes a display section 51 that displays various information to the user, and an operation section 52 that accepts operation input by the user.
The display unit 51 is configured by a color liquid crystal display or the like, and displays operation screens and the like (various setting screens, various buttons, operation status of each function, etc.) according to display control signals input from the control unit 20 .
The operation unit 52 includes a touch panel provided on the screen of the display unit 51 and various hard keys arranged around the screen of the display unit 51 . When a button displayed on the screen is pressed with a finger, a touch pen, or the like, the operation unit 52 detects the XY coordinates of the pressed power point as a voltage value, and controls an operation signal associated with the detected position. Output to unit 20 . Note that the touch panel is not limited to the pressure-sensitive type, and may be, for example, an electrostatic type or an optical type. Further, when a hard key is pressed, the operation unit 52 outputs an operation signal associated with the pressed key to the control unit 20 . By operating the operation unit 52, the user can perform settings related to image formation such as image quality settings, magnification settings, application settings, output settings and paper settings, paper transport instructions, and device stop operations.

The environment detection unit (detection unit) 60 is, for example, a temperature and humidity sensor, and detects environmental information (environmental change) such as temperature and humidity in the device.

In this embodiment, as shown in FIG. 4A, four light sources 1 (LD1 to LD4) are arranged at regular intervals in the main scanning direction. In this embodiment, the light source unit 11 includes a plurality (four) of light sources 1 (LD1 to LD4). The number of light sources 1 constituting the light source unit 11 is not limited to four, and may be any number as long as it is plural.
As shown in FIG. 4(B), when printing a straight line at three points in the main scanning direction of the paper P, the light source unit 11 emits light at the light emission timings shown in FIG. 4(A). is repeatedly controlled in the sub-scanning direction. In the example shown in FIG. 4A, control is performed so that light is emitted in order from the light source 1 on the rear end side in the main scanning direction (that is, in the order of LD4→LD3→LD2→LD1). In addition, the symbol X2 in the drawing indicates the distance between the light sources 1 adjacent in the main scanning direction, and indicates the light emission time of each light source 1. FIG. That is, each light source 1 is controlled to emit light (scan) for a time corresponding to the distance between adjacent light sources 1 . Reference symbol X1 in the drawing indicates the distance between the light source 1 (LD1) on the leading end side in the main scanning direction and the light source 1 (LD4) on the trailing end side in the main scanning direction. and the timing at which the light source 1 (LD1) on the leading end side in the main scanning direction starts emitting light.

In the configuration of the image forming apparatus 1000 according to the present embodiment, the main scanning interval (inclination) for each light source 1 at the main scanning position changes depending on the lens accuracy of the fθ lens and the mechanical adjustment accuracy. , the center, and the rear end, as shown in FIG. 5, even if the front end is a straight line, there is a case where the printing position shifts at the center or the rear end and the line is no longer a straight line.
Therefore, in this embodiment, in order to suppress the occurrence of pitch unevenness as described above, the main scanning interval (main scanning interval measured in the production process) stored in the storage unit 30 and the light receiving unit 6 (photodiodes PD11, PD12) ), frequency modulation is applied to each light source 1 based on the calculated frequency modulation rate (the frequency modulation rate of each light source 1 is changed), and the modulation result is The light emission timing of each light source 1 is controlled based on.

One example of a method of measuring the inclination (main scanning interval) of each light source 1 at a plurality of main scanning positions in the production process is a method using a sensor (photodiode).
Specifically, as shown in FIG. 6, a plurality of sensor substrates 70 are fixedly arranged so as to correspond to respective positions of the leading edge, the center, and the trailing edge in the main scanning direction when viewed from the image writing unit 100. The inclination (main scanning interval) of each light source 1 at the scanning position is measured. Each sensor substrate 70 is provided with a pair of photodiodes PD1 and PD2. The photodiodes PD1 and PD2 function as the second measuring section of the invention. In the example shown in FIG. 6, the sensor substrates 70 are arranged so as to correspond to the respective positions of the leading edge, the center, and the trailing edge in the main scanning direction. It is also possible to place more sensor substrates 70 for each position in the direction.
Here, the light emitted from the light source 1 (LD4) on the rear end side in the main scanning direction enters the photodiode PD1 on the front end side in the main scanning direction until it enters the photodiode PD2 on the rear end side in the main scanning direction. Time A (see FIG. 7A), light emitted from the light source 1 (LD4) on the rear end side in the main scanning direction is incident on the photodiode PD1 on the front end side in the main scanning direction, and When the time required for the light emitted from the light source 1 (LD1) to enter the photodiode PD2 on the rear end side in the main scanning direction is B (see FIG. 7B), the inclination between LD1 and LD4 (main scanning The interval) X1 can be calculated using the following formula (1). Also, the inclination (main scanning interval) X2 between adjacent LDs can be calculated using the following equation (2).
X1=B-A (1)
X2=X1/3 (2)
The main scanning interval of each light source 1 measured by the second measuring unit (photodiodes PD1, PD2) in the production process is stored in the storage unit 30. FIG.

In the examples shown in FIGS. 6 and 7, the method of measuring the main scanning interval of each light source 1 using a pair of photodiodes PD1 and PD2 during the production process is described. When measuring the main scanning interval of each light source 1, a pair of photodiodes PD11 and PD12 provided on each substrate (SOS substrate 61, EOS substrate 62) constituting the light receiving section 6 is used, and the same method as described above is used. can do.

In the present embodiment, the control unit 20 controls the irradiation start position outside the image area and the The data of the irradiation end positions are compared to calculate the correction value of the area (main scanning positions other than the irradiation start position and the irradiation end position) that cannot be measured by the actual machine after the start of operation.
FIG. 8 shows an example of data before the change measured in the production process and data after the change measured on the actual machine after the start of operation. In the graph shown in FIG. 8, the X-axis is the sensor position (the distance from the position of the substrate placed at the irradiation start position), and the Y-axis is the main scanning interval (the amount of deviation from LD1 to LD4). Reference character L1 in the figure indicates measurement data before change, and reference character L2 in the figure indicates measurement data after change. Further, reference symbol C1 in the figure is measurement data of the irradiation start position (SOS substrate 61), and reference symbol C2 in the figure is measurement data of the irradiation end position (EOS substrate 62).
Specifically, the coordinates of the measured data before change are (X(n), Y(n)), and the measured data after change are (X'(n), Y'(n)). This embodiment exemplifies a configuration measured at six main scanning positions (a configuration in which six substrates are arranged in the production process). n is the position (order) of the substrate, and 1 to 6 are input according to the position of the substrate. The irradiation start position (SOS substrate 61) is n=1, and the irradiation end position (EOS substrate 62) is n=6.
The correction characteristic A(n) before change at each main scanning position is calculated using the following formula (3).
A(n)=(Y(n)-Y(n-1))/(X(n)-X(n-1)) (3)
The post-change correction value A'(n) at each main scanning position is calculated using the following equation (4).
A′(n)=(Y′(6)−Y(6))/(Y′(1)−Y(1))×A(n) (4)
This correction value A'(n) is used as the frequency modulation rate of each light source 1 at each main scanning position.

The operation of the image forming apparatus 1000 according to this embodiment will be described below with reference to the flowchart of FIG.

First, the control unit 20 reads data stored in the storage unit 30 (step S101).

Next, the control unit 20 determines whether or not the data read in step S101 is a correction value (frequency modulation rate of each light source 1) (step S102).
When the control unit 20 determines that the data read in step S101 is the correction value (step S102: YES), the process proceeds to step S104.
On the other hand, the control unit 20 determines that the data read in step S101 is not the correction value (that is, the measured value (the main scanning interval measured by the second measurement unit (photodiodes PD1 and PD2))). If so (step S102: NO), the process proceeds to the next step S103.

At step S103, the control unit 20 calculates a correction value at each main scanning position based on the data (measured value) read at step S101.

In step S104, the control unit 20 frequency-modulates each light source 1 based on the correction value read out in step S101 or the correction value calculated in step S103.

Next, the control unit 20 determines whether or not a predetermined condition is satisfied (step S105). Here, the predetermined condition is a condition under which the main scanning interval of each light source 1 may change. For example, a predetermined time has passed since the frequency modulation in step S104. Here, an environmental change (temperature change) exceeding a predetermined level is, for example, a change to some extent that the optical system may be deformed. Also, the predetermined time is a certain amount of time during which there is a possibility that deterioration of the optical system will occur.
If the control unit 20 determines that a predetermined condition is satisfied (for example, a predetermined environmental change or more has been detected, or a predetermined period of time has elapsed) (step S105: YES), the process proceeds to the next step S106. .
On the other hand, if the control unit 20 determines that the predetermined condition is not satisfied (for example, a predetermined environmental change or more has not been detected, or the predetermined time has not elapsed) (step S105: NO), the predetermined condition The process of step S105 is repeated until it is determined that

In step S106, the control unit 20 acquires the measured value (main scanning interval) measured by the first measuring unit (photodiodes PD11 and PD12).

Next, the control unit 20 calculates a correction value at each main scanning position based on the measured value acquired in step S106 and the measured value stored in the storage unit 30 (step S107). Specifically, the control unit 20 calculates the correction value A'(n) at each main scanning position using the above equations (3) and (4).
After that, the control unit 20 proceeds to step S104, and frequency-modulates each light source 1 based on the correction value calculated in step S107.

As described above, the image forming apparatus 1000 according to the present embodiment emits a plurality of light beams (laser beams L) emitted from a plurality of light sources 1 according to image data on the image carrier (photoreceptor 200) in the main scanning direction. an image forming unit 10 for scanning to form an image, a modulating unit (control unit 20) for frequency-modulating each light source 1 according to the main scanning interval at a plurality of main scanning positions of a plurality of light beams, and a modulation A light emission control unit (control unit 20) that controls the light emission timing of each light source 1 based on the modulation result by the unit, a first measurement unit (photodiodes PD11, PD12) that measures the main scanning interval, and a plurality of and a storage unit 30 that stores the main scanning interval measured by the second measuring unit (photodiodes PD1, PD2) arranged to correspond to the main scanning position. Further, the modulation unit calculates the frequency modulation rate of each light source 1 based on the main scanning interval stored in the storage unit 30 and the main scanning interval measured by the first measurement unit, and based on the calculated frequency modulation rate to apply frequency modulation to each light source 1.
Therefore, according to the image forming apparatus 1000 of the present embodiment, it is possible to correct the tilt of each light source 1 at each main scanning position, thereby reducing the occurrence of pitch unevenness. In particular, since it is possible to cope with changes over time that occur in the actual machine, it is possible to reduce the occurrence of pitch unevenness even in the actual machine after the start of use.

Further, according to the image forming apparatus 1000 according to the present embodiment, the first measuring section is arranged near the irradiation start position and the irradiation end position outside the image area.
Therefore, according to the image forming apparatus 1000 according to the present embodiment, the main scanning interval can be measured by the measurement unit arranged at a position that does not interfere with the irradiation of the image area. , the occurrence of pitch unevenness can be reduced.

Further, according to the image forming apparatus 1000 according to the present embodiment, the detection section (environment detection section 60) that detects environmental changes within the apparatus is provided. Further, when the detection unit detects an environmental change of a predetermined value or more, the modulation unit modulates each light source 1 based on the main scanning interval stored in the storage unit 30 and the main scanning interval measured by the first measurement unit. A frequency modulation rate is calculated, and each light source 1 is frequency-modulated based on the calculated frequency modulation rate.
Therefore, according to the image forming apparatus 1000 according to the present embodiment, each light source 1 can be frequency-modulated when there is a risk of deformation of the optical system. It is possible to correct the tilt of each image.

Further, according to the image forming apparatus 1000 according to the present embodiment, the modulation unit changes the main scanning interval stored in the storage unit 30 and the main scanning interval measured by the first measurement unit when the predetermined time has passed. Based on this, the frequency modulation rate of each light source 1 is calculated, and each light source 1 is frequency-modulated based on the calculated frequency modulation rate.
Therefore, according to the image forming apparatus 1000 of the present embodiment, each light source 1 can be frequency-modulated when there is a risk of deterioration of the optical system. The inclination of each light source 1 can be corrected.

As described above, the present invention has been specifically described based on the embodiments, but the present invention is not limited to the above embodiments, and can be modified without departing from the scope of the invention.

For example, in the above-described embodiment, as the predetermined condition, when a predetermined or more environmental change (temperature change) is detected, or when a predetermined time elapses, the first measurement units (photodiodes PD11 and PD12) measure Although the correction value at each main scanning position is calculated based on the measured value stored in the storage unit 30 and the measured value stored in the storage unit 30, the present invention is not limited to this. For example, when the main scanning interval is calculated based on density information of an image (chart) for calculating the main scanning interval, and a change in the main scanning interval is detected based on the calculation result, the photodiode PD11, A correction value at each main scanning position may be calculated based on the measured value measured by the PD 12 and the measured value stored in the storage unit 30 .
Specifically, first, the control unit 20 causes the image forming unit 10 to form an image (chart) for calculating the main scanning interval. That is, the control section 20 functions as an image forming control section of the present invention. Next, the control unit 20 calculates main scanning intervals at a plurality of main scanning positions of each light source 1 based on the density information of the image (chart) acquired by the acquisition unit (camera 40). That is, the control section 20 functions as a calculation section of the present invention. Next, when the control unit 20 detects a change in the main scanning interval based on the calculation result, the control unit 20 calculates each main scanning interval based on the measured values measured by the photodiodes PD11 and PD12 and the measured values stored in the storage unit 30. A correction value at the scanning position is calculated.
As described above, the image forming control unit (control unit 20) that causes the image forming unit 10 to form a chart for calculating the main scanning interval, and the acquisition that acquires the density information of the chart formed by the image forming unit 10. section (camera 40) and a calculation section (control section 20) that calculates the main scanning interval based on the density information, and the modulation section detects a change in the main scanning interval based on the calculation result of the calculation section. In this case, the frequency modulation rate of each light source 1 is calculated based on the main scanning interval stored in the storage unit 30 and the main scanning interval measured by the first measurement unit, and each light source is calculated based on the calculated frequency modulation rate. 1 is frequency-modulated, it is possible to frequency-modulate each light source 1 when a change in the main scanning interval is actually detected. can be corrected.

Further, in the above-described embodiment, as an example of a method of measuring the main scanning interval of each light source 1 at a plurality of main scanning positions in the production process, the configuration using the photodiodes PD1 and PD2 has been exemplified and explained. is not limited to For example, instead of using the photodiodes PD1 and PD2, a camera (CCD camera) may be used.

Further, in the above-described embodiment, the configuration in which the light receiving section 6 detects the laser beam L reflected by the second reflecting mirror 5 is illustrated and described, but the configuration is not limited to this. For example, a configuration may be adopted in which the second reflecting mirror 5 is not provided and the light receiving section 6 is arranged at the position of the second reflecting mirror 5 . Further, the light receiving unit 6 does not necessarily have to be arranged inside the image writing unit 100, and can be arranged outside the image writing unit 100 as long as it can detect the laser light L at the start and end of the irradiation. may have been

In addition, the detailed configuration and detailed operation of each device constituting the image forming apparatus can be changed as appropriate without departing from the gist of the present invention.

1000 Image forming apparatus 10 Image forming unit 100 Image writing unit 11 Light source unit 1 Light source 2 Deflector 3 fθ lens 4 First reflecting mirror 5 Second reflecting mirror 6 Light receiving unit 61 SOS substrate 62 EOS substrate PD11, PD12 Photodiode (second 1 measurement part)
200 photoreceptor (image carrier)
210 charging unit 220 developing unit 300 intermediate transfer belt 400 transfer roller 500 fixing unit 20 control unit (modulation unit, light emission control unit, image formation control unit, calculation unit)
30 storage unit 40 camera (acquisition unit)
50 operation panel 51 display unit 52 operation unit 60 environment detection unit (detection unit)
70 sensor substrates PD1, PD2 photodiodes (second measurement unit)
L laser light (ray)

Claims (7)

an image forming unit that scans an image carrier in a main scanning direction with a plurality of light beams emitted from a plurality of light sources according to image data to form an image;
a modulation unit that frequency-modulates each light source according to a main scanning interval at a plurality of main scanning positions of the plurality of light beams;
a light emission control unit that controls the light emission timing of each light source based on the result of modulation by the modulation unit;
a first measuring unit that measures the main scanning interval;
a storage unit that stores the main scanning intervals measured by a second measuring unit arranged to correspond to the plurality of main scanning positions in the production process;
with
The modulation unit calculates the frequency modulation rate of each light source based on the main scanning interval stored in the storage unit and the main scanning interval measured by the first measurement unit, and based on the calculated frequency modulation rate and applying frequency modulation to each of the light sources. 2. The image forming apparatus according to claim 1, wherein the first measurement unit is arranged near an irradiation start position and an irradiation end position outside the image area. Equipped with a detection unit that detects environmental changes in the device,
The modulating unit modulates each of the light sources based on the main scanning interval stored in the storage unit and the main scanning interval measured by the first measuring unit when the detecting unit detects an environmental change of a predetermined value or more. 3. The image forming apparatus according to claim 1, wherein the frequency modulation rate of is calculated, and each light source is frequency-modulated based on the calculated frequency modulation rate. an image forming control unit that causes the image forming unit to form a chart for calculating the main scanning interval;
an acquisition unit that acquires density information of the chart formed by the image forming unit;
a calculation unit that calculates the main scanning interval based on the density information;
with
The modulating unit adjusts the main scanning interval stored in the storage unit and the main scanning interval measured by the first measuring unit when a change in the main scanning interval is detected based on the calculation result of the calculating unit. The image formation according to any one of claims 1 to 3, wherein the frequency modulation rate of each light source is calculated based on the calculated frequency modulation rate, and the frequency modulation is applied to each light source based on the calculated frequency modulation rate. Device. The modulation unit calculates a frequency modulation rate of each light source based on the main scanning interval stored in the storage unit and the main scanning interval measured by the first measurement unit when a predetermined time has elapsed, 5. The image forming apparatus according to claim 1, wherein each light source is frequency-modulated based on the calculated frequency modulation rate. an image forming unit that scans an image carrier in a main scanning direction with a plurality of light beams emitted from a plurality of light sources according to image data to form an image; and main scanning of the plurality of light beams at a plurality of main scanning positions An image forming apparatus comprising: a first measuring unit that measures an interval; and a storage unit that stores the main scanning interval measured by a second measuring unit arranged to correspond to the plurality of main scanning positions in a production process. A light emission control method for a device,
a modulation step of frequency-modulating each light source according to a main scanning interval at a plurality of main scanning positions of the plurality of light beams;
a light emission control step of controlling the light emission timing of each of the light sources based on the modulation result of the modulation step;
including
In the modulating step, the frequency modulation rate of each light source is calculated based on the main scanning interval stored in the storage unit and the main scanning interval measured by the first measurement unit, and based on the calculated frequency modulation rate and applying frequency modulation to each of the light sources. an image forming unit that scans an image carrier in a main scanning direction with a plurality of light beams emitted from a plurality of light sources according to image data to form an image; and main scanning of the plurality of light beams at a plurality of main scanning positions An image forming apparatus comprising: a first measuring unit that measures an interval; and a storage unit that stores the main scanning interval measured by a second measuring unit arranged to correspond to the plurality of main scanning positions in a production process. device computer,
a modulation unit that frequency-modulates each light source according to a main scanning interval at a plurality of main scanning positions of the plurality of light beams;
a light emission control unit that controls the light emission timing of each light source based on the result of modulation by the modulation unit;
function as
The modulation unit calculates the frequency modulation rate of each light source based on the main scanning interval stored in the storage unit and the main scanning interval measured by the first measurement unit, and based on the calculated frequency modulation rate and applying frequency modulation to each of the light sources.

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