JP2000218860A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain color images without a positional shift by correcting a scanning position relationship of a scanning light emitted from each scanning optical device when a temperature change of the optical scanning device detected by a temperature-detecting means is not smaller than a predetermined value. SOLUTION: An interior of each scanning optical apparatuses 111-114 is constituted of a motor driver 111a for rotating a polygon mirror, a temperature sensor 111b for detecting a temperature inside the scanning optical apparatus and an LD driver 111c for driving an LD (laser diode). When a temperature change of outputs of the temperature sensors 111b-114b from the scanning optical apparatuses 111-114 is not smaller than a predetermined value, a positional shift of each scanning optical apparatus 111-114 is corrected on the basis of outputs of an index sensor and a reflecting type sensor, and laser beams are irradiated to an image carrier. Color images without a positional shift can be obtained while a throughput is maintained to be an appropriate value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to an improvement in an image forming apparatus for collectively transferring a multicolor image.

[0002]

2. Description of the Related Art Conventionally, one scanning optical device is mounted in an image forming apparatus, and an image carrier is rotated a plurality of times to sequentially rotate Y (yellow), M (magenta), C (cyan), and K (black). And a color image is formed by superimposing the toner images. This image forming apparatus is inexpensive because it has one scanning optical system, but it takes time because the image carrier needs to be rotated a plurality of times to form a color image.

In order to reduce the time for forming a color image, an image forming apparatus having a plurality of scanning optical devices is used. In this image forming apparatus, a plurality of scanning optical systems scan with a plurality of scanning lights in the same time zone to scan Y,
Since the M, C, and K toner images are formed and the toner images are superimposed on the image carrier or the recording medium, a color image can be formed in a short time.

FIG. 8 is a configuration diagram of a color image forming apparatus. In this example, a color image forming apparatus using four color toners of Y, M, C, and K is arranged by arranging four scanning optical devices in the sub-scanning direction. In the figure, a belt-shaped image carrier 100 is fed in a clockwise direction (the direction of the arrow in the figure) while being wound around rollers 101 to 103. In the vicinity of the image carrier 100, scanning optical devices 111 to 114 are arranged in the sub-scanning direction so as to face the image carrier 100.

Each of the scanning optical devices 111 to 114 includes a light source, a collimator lens on which a beam generated from the light source is incident, a deflector for deflecting the light beam having passed through the collimator lens in the main scanning direction, and a deflector. At least an image forming lens for forming an image of the light beam after passing through the device on the surface to be scanned of the image carrier.

Here, the scanning optical device 111 forms a latent image for Y (yellow) using a laser beam.
Numeral 2 denotes a latent image for M (magenta) using laser light, 113 denotes a latent image for C (cyan) using laser light, and 114 denotes K (black) using laser light. ) To form a latent image.

In the preceding stage of each of the scanning optical devices 111 to 114, there are provided charging units 121, 122, 123, and 124 for applying Y, M, C, and K charges to the image carrier 100, respectively. At the subsequent stage of the devices 111 to 114, the latent images formed by the respective scanning optical devices are respectively represented by Y, M, C,
Developing devices 131 to 134 for developing using a K developer
Is provided.

The transfer paper 142 in the paper supply unit 141 is carried out by a paper supply roller 143 and is fed to the transfer unit 151 by a pair of conveyance rollers 144 and a timing roller 145. The transfer unit 151 includes a transfer pole 152 that transfers the toner image on the image carrier 100 to the transfer paper 142 by corona discharge, and a separation pole 153 that separates the transfer paper 142 from the image carrier 100 by AC discharge. I have.

The fixing section 161 includes a heat roller 162 and a pressure roller 163 and fuses the toner image to the transfer paper 142. The transfer paper 142 after the fixing is discharged to a discharge tray by a transport unit 171 at a subsequent stage. The toner remaining on the image carrier 100 after the transfer is scraped off by the cleaning unit 191 and stored in the collection box 192.

In this apparatus, around the image carrier 100,
Scanning optical devices 111 to 111 for each color of Y, M, C, and K
114 and developing devices 131 to 134 are arranged in the sub-scanning direction for each color.
An electrostatic latent image of each color is formed and developed by the developing devices 131 to 134 so as to accurately overlap the toner images of other colors. That is, the scanning optical device 111 and the developing device 13
After forming a Y toner image using
And a developing device 132 to form an M toner image on the Y toner image, a scanning optical device 113 and a developing device 133 are used to form a C toner image, and finally a scanning optical device 114 A color toner image is completed by superimposing and forming a K toner image using the developing device 134 and the developing device 134, and is transferred to the transfer paper 142 by the transfer unit 151.

[0011]

However, in an image forming apparatus having a plurality of scanning optical devices, an image forming apparatus or a recording medium is formed in order to form an appropriate color image without misalignment.
Scanning light emitted by each scanning optical device needs to be scanned on the image carrier at appropriate intervals.

When the power of the image forming apparatus is turned on, the temperature inside the apparatus increases due to the heat generated from the fixing device and the like. When the assembly of the image forming apparatus is completed, each scanning optical device is adjusted and the scanning light is adjusted. Even if the interval is proper, each of the scanning optical devices may be thermally deformed due to the above-mentioned temperature rise, and the appropriate interval of the scanning light may be shifted.
For example, in the case of a scanning optical device using a plastic lens, the internal temperature rises due to the heat generated by a driving device in the scanning optical device, and the plastic lens is deformed, whereby the proper interval of the scanning light is shifted.

Although it is certain that feedback control is performed in order to correct a position shift due to a temperature rise, control using a registration mark or the like requires time for measuring the amount of position shift, and frequent feedback control is required. Doing so has a significant effect on throughput.

[0014] The present invention has been made in view of such a problem, and while maintaining the throughput at an appropriate value,
An image forming apparatus capable of obtaining a color image without positional displacement is provided.

[0015]

According to a first aspect of the present invention, there is provided an image forming apparatus having a plurality of scanning optical devices for scanning an image carrier, wherein the image forming device includes a plurality of scanning optical devices. A temperature detecting means installed in the vicinity thereof, and correcting a scanning positional relationship of scanning light emitted from each scanning optical apparatus when a temperature change of the scanning optical apparatus detected by the temperature detecting means becomes a predetermined value or more. And a correction control means.

According to the present invention, since the correction control means optimally controls the scanning positional relationship of the scanning light in accordance with the temperature change in the scanning optical device detected by the temperature detecting means, a color image without positional displacement is obtained. be able to.

(2) A second aspect of the present invention for solving the above-mentioned problem is an image forming apparatus having a plurality of scanning optical devices for scanning on an image carrier, wherein the image forming device is provided inside or near the scanning optical device. Temperature detecting means, and correction control means for correcting a scanning positional relationship of scanning light emitted from each scanning optical device when a temperature difference between the scanning optical devices detected by the temperature detecting means becomes equal to or more than a predetermined value. It is characterized by having.

According to the present invention, the correction control means optimally controls the scanning positional relationship of the scanning light in accordance with the temperature difference between the scanning optical devices detected by the temperature detecting means, so that a color image without positional displacement is obtained. be able to.

(3) A third invention for solving the above-mentioned problems is an image forming apparatus having a plurality of scanning optical devices for scanning on an image carrier, wherein a scanning surface of scanning light emitted from each scanning optical device is provided. A mark detecting means for detecting a detection mark for detecting the positional relationship above, and calculating a relative displacement of the scanning light on the scanning surface based on a detection result by the mark detecting means, and A first correction control unit for correcting a positional relationship on a scanning surface, a temperature detection unit provided inside or near the scanning optical device, and a temperature change in the scanning optical device monitored by the temperature detection unit. When the temperature change falls below the threshold value, the position deviation of the scanning light corresponding to the temperature change on the scanning surface is predicted, and the positional relationship of the scanning light on the scanning surface is corrected by the predicted position deviation. And second correction control means It is characterized in that.

According to the present invention, the feedback control is normally performed by the first correction control means, and when the temperature change in the scanning optical device becomes equal to or less than the threshold value, the position shift by the second correction control means is corrected. By performing the predictive control, the throughput can be maintained at an appropriate value.

(4) A fourth invention for solving the above-mentioned problem is an image forming apparatus having a plurality of scanning optical devices for scanning on an image carrier, wherein a scanning surface of scanning light emitted from each scanning optical device is provided. A mark detecting means for detecting a detection mark for detecting the positional relationship above, and calculating a relative displacement of the scanning light on the scanning surface based on a detection result by the mark detecting means, and First correction control means for correcting the positional relationship on the scanning surface, temperature detecting means provided inside or near the scanning optical device, and monitoring the temperature difference between the scanning optical devices by the temperature detecting means; When the temperature change becomes equal to or less than the threshold value, a position shift of the scanning light corresponding to the temperature difference on the scanning surface is predicted, and the position shift is estimated by:
A second correction control unit for correcting a positional relationship of the scanning light on the scanning surface.

According to the present invention, the feedback control is normally performed by the first correction control means, and when the temperature difference between the scanning optical devices becomes equal to or less than the threshold value, the displacement correction by the second correction control means is performed. By performing the predictive control, the throughput can be maintained at an appropriate value.

(5) In this case, two thresholds are set as the first threshold and a second threshold having a temperature change or a temperature difference larger than the first threshold, When the temperature change in or near the scanning optical device or the temperature difference between the scanning optical devices exceeds the first threshold value, the correction by the second correction control means is performed, and the temperature exceeds the second threshold value. The correction by the first correction control means is performed.

According to the present invention, two threshold values, large and small, are set, and the temperature change in the scanning optical device or the temperature difference between the scanning optical devices falls within the range of these threshold values.
By selecting the feedback control and the predictive control, the throughput can be maintained at an appropriate value.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a conceptual diagram of the configuration of the present invention. 8 are denoted by the same reference numerals. In the figure, reference numeral 20 denotes a CPU for controlling the entire operation.
(Microprocessor), which is a correction control means described later. 111 is a Y scanning optical device connected to the CPU 20, 112 is an M scanning optical device connected to the CPU 20,
113 is a C scanning optical device connected to the CPU 20;
Reference numeral 4 denotes a K scanning optical device connected to the CPU 20. These scanning optical devices irradiate the image carrier 100 with a beam corresponding to an image.

As shown in FIG. 2, the inside of each of the scanning optical devices 111 to 114 includes a motor driver 111a for rotating a polygon mirror, a temperature sensor 111b for detecting a temperature in the scanning optical device, and an LD (laser diode). It comprises an LD driver 111c to be driven. The output of the temperature sensor 111b is notified to the CPU 20,
The PU 20 outputs a motor driver signal and an LD drive signal to each scanning optical device. The above operation is the same for the other scanning optical devices 112 to 114.

Referring again to FIG. 1, reference numeral 100 denotes an image carrier on which an electrostatic latent image is formed. As the image carrier, FIG.
Or a drum shape. Reference numeral 210 denotes a reflection sensor that reads reflected light from a predetermined image (registration mark) formed on the image carrier 100 to detect a deviation, and 220 denotes an index sensor that detects a reference position in scanning with a laser beam. Also, the output is notified to the CPU 20.

In the device configured as described above, the CP
U20 receives the output of the index sensor 220 and the output of the reflection type sensor 210, and receives scanning optical devices 111-11.
The laser beam is irradiated onto the image carrier 100 after correcting the positional deviation of No. 4. In this case, the CPU 20 includes the temperature sensor 1 output from each of the scanning optical devices 111 to 114.
The CPU 20 receives the output of each temperature sensor and scans the beam in a direction to offset the influence of the temperature (feedback control).

FIG. 3 is a diagram showing a configuration example of the scanning optical system. The circuit unit 480 includes the CPU 20 and has a C
The output of PU 20 drives a laser diode (LD) 470. The output light of the LD is supplied to a polygon mirror 49 via a collimator lens 491 → a cylindrical lens 492.
3 and the reflected light of the polygon mirror 493 is fθ
The light passes through the lens 494 and enters the cylindrical lens 495, and the light transmitted through the cylindrical lens 495 is incident on the image carrier 100. Here, the polygon mirror 49
As the 3 rotates, a beam is irradiated onto the image carrier 100 in the main scanning direction.

According to the present invention, the CPU 20 calculates the degree of expansion and contraction of the optical lens and the like based on the temperature difference according to the temperature change in the scanning optical device or the temperature difference between the scanning optical devices.
The width of the dots in the main scanning direction is adjusted so that the distance from point A to point B in FIG. 3 does not differ for each color (the same applies to the sub-scanning direction). Thereby, since the toner of each color completely overlaps, the color shift can be eliminated.

According to this embodiment, the correction control means (CPU 20) optimally controls the scanning positional relationship of the scanning light according to the temperature change in the scanning optical device detected by the temperature sensor. No color images can be obtained.

The above description has been given of the case of correcting the positional deviation based on the temperature change in the scanning optical device. However, even when the temperature difference between the scanning optical devices reaches a predetermined value, the scanning position of the scanning light is similarly changed. Since the relationship is optimally controlled, it is possible to obtain a color image with no displacement.

Next, the operation of the present invention will be described in detail. FIG. 4 is a flowchart showing an example of a start sequence operation. When the power is turned on (S1), the CPU 20 starts a start sequence. In the start sequence,
First, the CPU 20 reads the output of the Y temperature sensor 111b (S2), and stores the read data in the memory as TY1 and TY3 (S3). Here, three registers (register 1 to register 3) for TY1, TY2, and TY3 are provided in a memory built in the CPU 20, and each measurement data is stored in each register as a default value. It is memorized. Here, the same measured value is stored in the register 1 and the register 3 (the same applies hereinafter).

Next, the CPU 20 sets the M temperature sensor 112
b output is read (S4), and the measured temperature is set to TM1, T
It is stored in the memory as M3 (S5). TM1 for M
Registers from the first to the third TM3 are provided. next,
The CPU 20 reads the output of the C temperature sensor 113b (S6), and stores the measured temperatures in the memory as TC1 and TC3 (S7). Registers 1 to 3 of TC1 to TC3 are also provided for C. Next, CPU
20 reads the output of the K temperature sensor 114b (S
8) The measured temperatures are stored in the memory as TK1 and TK3 (S9). Registers 1 to 3 of TK1 to TK3 are also provided for K.

After the temperatures of Y, M, C, and K are stored in the registers by the temperature sensor, the temperatures of the respective colors are read by the temperature sensors. That is, the CPU 20 first reads the output of the Y temperature sensor 111b (S1).
0), the measured temperature is stored in the in-memory register 2 as TY2 (S11). Next, the CPU 20 reads the output of the M temperature sensor 112b (S12), and stores the measured temperature in the register 2 as TM2 (S13). next,
The CPU 20 reads the output of the C temperature sensor 113b (S14) and stores the measured temperature as TC2 in the register 2 (S15). Finally, the CPU 20 reads the output of the K temperature sensor 114b (S16), and stores the measured temperature in the register 2 as TK2 (S17).

According to the above sequence, each of the registers 1 to
TY1 to TY3, TM1 to TM3, TC1
To TC3 and TK1 to TK3 are read (the first and third data have the same value at first). When all the measurement data are read as default values, the CPU 20 executes color registration automatic correction control (S18). The color registration automatic correction control means reading a registration mark provided on the image carrier, determining a position for each color, and performing position correction by feedback. This ends the start sequence (S19). With the above processing, the position correction control using the default value has been executed.

FIGS. 5 to 7 are flow charts showing an example of a normal routine of the present invention. First, the CPU 20 opens the door (specifically, the lid is open) or jams (JA).
It is checked whether M) has occurred (S1). If no lid release or jam has occurred, it is checked whether 5 minutes have elapsed since the last temperature measurement (S2).
If there is a lid release or a jam, the process proceeds to step S3.

In step S3, the CPU 20 reads the output of the Y temperature sensor 111b and stores the measured temperature in the register 3 as TY3 (S4). At this point, the temperature TY3 stored as the default value or the previously measured temperature TY3 is changed to a new value (the same applies hereinafter). Next, the CPU 20 reads the output of the M temperature sensor 112b (S5), and stores the measured temperature as TM3 in the register 3 (S6). Next, the CPU 20 reads the output of the C temperature sensor 113b (S7) and stores the measured temperature as TC3 in the register 3 (S8). Next, C
The PU 20 reads the output of the K temperature sensor 114b (S9), and stores the measured temperature in the register 3 as TK3 (S10).

Next, the CPU 20 obtains a shift amount KY1 between Y and K due to a temperature change based on the data stored in each register by the following equation (S11). KY1 = A × C × ((TY3-TY1) − (TK3-T
K1)) + B × C × ((TY3-TY1) + (TK3-
TK1)) / 2 where A is a temperature coefficient and the unit is μm / ゜ C, C is a temperature gradient coefficient, and B is a temperature coefficient and the unit is μm / ゜ C. TY
3 and TY1, TK3 and TK1 are measured temperatures stored in registers, respectively. The following calculation includes a sequence for obtaining the shift amount from the value between the registers 3 and 1, and a sequence for obtaining the shift amount from the registers 2 and 3.

Thereafter, similarly, a shift amount KM1 between K and M due to a temperature change is obtained (S12). Next, a deviation KC1 between K and C due to a temperature change is obtained (S13). Next, a deviation CM1 between C and M due to a temperature change is obtained (S1).
4). Next, a shift amount CY1 between C and Y due to a temperature change is obtained (S15). Next, a deviation amount MY1 between M and Y due to a temperature change is obtained (S16).

Next, based on the data stored in each register, the CPU 20 calculates a deviation amount K between Y and K due to a temperature change.
Y2 is obtained by the following equation (S17). KY2 = A × C × ((TY3-TY2) − (TK3-T
K2)) + B × C × ((TY3-TY2) + (TK3-
TK2)) / 2 Here, A is a temperature coefficient and a unit is μm / ゜ C, C is a temperature gradient coefficient, and B is a temperature coefficient and a unit is μm / ゜ C. TY
3 and TY2, and TK3 and TK2 are measured temperatures stored in the registers 3 and 2, respectively.

Thereafter, similarly, a deviation KM2 between K and M due to a temperature change is obtained (S18). Next, a deviation KC2 between K and C due to a temperature change is obtained (S19). Next, a deviation CM2 between C and M due to a temperature change is obtained (S2).
0). Next, a shift amount CY2 between C and Y due to a temperature change is obtained (S21). Next, a shift amount MY2 between M and Y due to a temperature change is obtained (S22). With the above procedure, all the deviation amounts are obtained.

Next, the CPU 20 determines the obtained deviation amount KY.
1, KM1, KC1, CM1, CY1, and MY1 are checked whether the absolute value is 100 or more (S2).
3). If any absolute value is 100 or more,
The CPU 20 executes the automatic color registration correction control by feedback (S24), and corrects the contents of the color misregistration correction table (S25). When the absolute value of the shift amount is large, the predictive control is impossible, so that the feedback control is executed to end the color shift correction quickly. Next, TY3 is moved to TY1, and TM3 is changed to TM1.
, TC3 is moved to TC1, and TK3 is moved to TK1 (S26). Upon completion of the above processing, the procedure returns to the first step S1.

Next, if the absolute value of the displacement amount in step S23 is 100 or less, the CPU 20 determines that the absolute value of any of KY2, KM2, KC2, CM2, CY2, and MY2 is 100 or less and 30 or more. It is checked whether there is (S27). If so, the CPU
In step S28, the color shift amount is predicted based on the values of KY2 to MY2, and the color shift correction value in the color shift table is corrected (S28). As a result, the image forming apparatus corrects the relative positional relationship of the color shift based on the corrected color shift correction value so that the colors are aligned, so that no position shift occurs. Then, TY3 is moved to TY2, TM3 is moved to TM2, and T
C3 is moved to TC2, and TK3 is moved to TK2 (S2
9) Return to the first step S1.

In step S27, KY2, KM
If the absolute value of any of 2, 2, CC2, CM2, CY2, and MY2 is 30 or less, there is no need for correction, and the process returns to the first step S1.

As described above, according to the embodiment of the present invention, when the temperature change in the scanning optical device becomes equal to or less than the threshold value, the second correction control means controls the displacement prediction. , The throughput can be maintained at an appropriate value.

Further, according to the embodiment of the present invention, when the temperature change between the scanning optical devices becomes equal to or less than the threshold value, the second correction control means performs the misregistration prediction control, whereby Throughput can be maintained at a reasonable value.

Further, two thresholds, large and small, are set, and feedback control and predictive control are performed depending on the range of these thresholds in a temperature change in the scanning optical device or a temperature difference between the scanning optical devices. By doing so selectively, the throughput can be maintained at a reasonable value.

According to the present invention, the misregistration correction is performed by the predictive control up to the assumed temperature, and the correct misregistration is corrected by the feedback control when the temperature greatly changes, thereby achieving both image quality and throughput. Can be achieved.

Next, a specific example of the positional deviation correction will be described. A reference clock is input to a plurality of delay circuits to obtain a plurality of delayed clocks each having a finely changed phase, and a delay signal whose phase is finely changed without changing the clock frequency is based on the number of synchronization stages of the delay signal. In order within a predetermined time. Thereby, the number of pulses in a predetermined time can be adjusted to a predetermined number, and as shown in FIG.
The relative displacement between AB on the surface of the image carrier 100 can be corrected for each color.

In the above-described embodiment, a case has been described as an example in which the displacement control for each color is automatically corrected by the correction control means. However, the present invention is not limited to this, and the operator can correct the scanning positional relationship of the scanning light emitted from each scanning optical system by an operable means such as an operation panel.

Alternatively, instead of the operator giving a control command from the operation panel, a command signal can be given from a computer connected to the image forming apparatus to correct the scanning positional relationship of the scanning light.

Alternatively, a time measuring means for measuring an elapsed time from a predetermined time is provided, and when the time measuring means notifies that the predetermined time has elapsed, the scanning position of the scanning light emitted from each scanning optical device is determined. Correction can also be made. According to this, it is possible to correct the scanning positional relationship of the scanning light after the lapse of the predetermined time.

Alternatively, a print number measuring means for measuring the number of prints from a predetermined point in time may be provided, and when the number of prints reaches the predetermined number, the scanning positional relationship of the scanning light emitted from each scanning optical device may be corrected. it can. According to this, when the predetermined number of prints is reached, the scanning positional relationship of the scanning light can be corrected.

Alternatively, an exchange detecting means for detecting an exchange operation of a component in the image forming apparatus is provided, and when the exchange operation of the exchange component is notified, the scanning positional relationship of the scanning light emitted from each scanning optical device is corrected. You can also do so.
According to this, the scanning positional relationship of the scanning light at the time of component replacement can be corrected.

Alternatively, a paper jam detecting means for detecting a paper jam generated in the image forming apparatus is provided to remove the jammed paper, and when the paper jam detection by the paper jam detecting means is removed, each scanning optical device is removed. It is also possible to correct the scanning positional relationship of the scanning light emitted from. According to this, the scanning positional relationship of the scanning light at the time of detecting a paper jam can be corrected.

Alternatively, an opening / closing operation detecting means for detecting an opening / closing operation of a door in the image forming apparatus is provided, and when the opening / closing operation of the door in the image forming apparatus is detected, scanning of scanning light emitted from each scanning optical device is performed. The positional relationship may be corrected. According to this, it is possible to correct the scanning positional relationship of the scanning light after the door is opened and closed.

Alternatively, when the power supply in the image forming apparatus is turned on, the scanning positional relationship of the scanning light can be corrected. According to this, when the power is on,
The scanning position relationship of the scanning light can always be corrected.

Alternatively, if the temperature change from the predetermined point in time at the output of the temperature detector disposed in or near the scanning optical device is less than a predetermined value, the next scanning positional relationship is not corrected. You can also This is because it is not necessary to correct the scanning positional relationship while the temperature change is small. According to this, it is not necessary to correct the scanning positional relationship when the temperature change is small.

According to the present invention, it is possible to correct the overall lateral magnification of the scanning light emitted from each scanning optical device, and / or the deviation in the main scanning direction, and / or the deviation in the sub scanning direction. As a result, more accurate positional deviation correction can be performed.

[0061]

As described in detail above, (1) According to the first aspect, the temperature detecting means installed in or near the scanning optical device, and the scanning detected by the temperature detecting means. When the temperature change of the optical device exceeds a predetermined value, the correction control means corrects the scanning positional relationship of the scanning light emitted from each scanning optical device, thereby detecting the temperature change in the scanning optical device detected by the temperature detecting means. , The correction control means optimally controls the scanning positional relationship of the scanning light, so that a color image without positional deviation can be obtained.

(2) According to the second aspect, the temperature difference between the temperature detecting means provided inside or near the scanning optical device and the scanning optical device detected by the temperature detecting means is equal to or more than a predetermined value. The correction control means corrects the scanning position relationship of the scanning light emitted from each scanning optical device when the scanning optical device is turned off. Is optimally controlled, so that a color image without positional deviation can be obtained.

(3) According to the third invention, the first correction control means for correcting the positional relationship of the scanning light on the scanning surface based on the detection result, and the temperature in the scanning optical device by the temperature detecting means. The change is monitored, and when the temperature change becomes equal to or less than the threshold value, a position shift of the scanning light corresponding to the temperature change on the scanning surface is predicted. With the second correction control means for correcting the positional relationship in the above, usually, the feedback control by the first correction control means is performed, and when the temperature change in the scanning optical device becomes equal to or less than the threshold value, By performing the position deviation prediction control by the second correction control means, the throughput can be maintained at an appropriate value.

(4) According to the fourth aspect, the first correction control means for correcting the positional relationship of the scanning light on the scanning surface based on the detection result, and the correction control means are provided inside or near the scanning optical device. The temperature is monitored by the temperature detecting means, and when the temperature change becomes equal to or less than the threshold value, the positional deviation of the scanning light corresponding to the temperature difference on the scanning surface is predicted. And the second correction control means for correcting the positional relationship on the scanning surface, the feedback control is normally performed by the first correction control means, and the temperature difference between the scanning optical devices is set to be equal to or less than the threshold value. In such a case, the throughput can be maintained at an appropriate value by performing the position deviation prediction control by the second correction control means.

(5) In this case, if the temperature change inside or near the scanning optical device or the temperature difference between the scanning optical devices exceeds the first threshold value, the correction by the second correction control means is performed. By performing the correction by the first correction control means when the second threshold value is exceeded,
Two thresholds, large and small, are set, and feedback control and predictive control are selected and performed depending on the range of the threshold value between the temperature change in the scanning optical device and the temperature difference between the scanning optical devices. Thus, the throughput can be maintained at a reasonable value.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating the configuration of the present invention.

FIG. 2 is a diagram illustrating a configuration example of a scanning optical device.

FIG. 3 is a diagram illustrating a mechanical configuration example of a scanning optical system.

FIG. 4 is a flowchart illustrating an operation example of a start sequence.

FIG. 5 is a flowchart illustrating an example of a normal routine.

FIG. 6 is a flowchart illustrating an example of a normal routine.

FIG. 7 is a flowchart illustrating an example of a normal routine.

FIG. 8 is a diagram illustrating a configuration example of a color image forming apparatus.

[Explanation of symbols]

 20 CPU 111 Y scanning optical device 111a Motor driver 111b Temperature sensor 112 M scanning optical device 112a Motor driver 112b Temperature sensor 113 C scanning optical device 113a Motor driver 113b Temperature sensor 114 K scanning optical device 114a Motor driver 114b Temperature sensor

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuyuki Tagami 2970 Ishikawacho, Hachioji-shi, Tokyo Konica Corporation F term (reference) 2C362 BA52 BA53 BA68 BA70 CA22 CA23 CA37 DA04 2H030 AA01 BB02 BB12 BB16 2H076 AB02 AB12 AB16 AB67 CA16 CA17 DA42 EA01 EA21

Claims (5)

[Claims] 1. An image forming apparatus having a plurality of scanning optical devices for scanning on an image carrier, comprising: a temperature detecting unit installed in or near the scanning optical device; An image forming apparatus comprising: a correction control unit configured to correct a scanning positional relationship of scanning light emitted from each scanning optical device when a temperature change of the scanning optical device becomes equal to or more than a predetermined value. 2. An image forming apparatus having a plurality of scanning optical devices for scanning on an image carrier, comprising: a temperature detecting unit provided in or near the scanning optical device; An image forming apparatus comprising: a correction control unit that corrects a scanning positional relationship of scanning light emitted from each scanning optical device when a temperature difference between the scanning optical devices becomes equal to or more than a predetermined value. 3. An image forming apparatus having a plurality of scanning optical devices for scanning on an image carrier, wherein a detection mark for detecting a positional relationship on a scanning surface of scanning light emitted from each scanning optical device is provided. A mark detecting means for detecting, and a first position correcting means for calculating a relative positional shift of the scanning light on the scanning surface based on a detection result by the mark detecting means to correct a positional relationship of the scanning light on the scanning surface. Correction control means, temperature detecting means installed in or near the scanning optical device, and monitoring temperature changes by the temperature detecting means, and responding to the temperature changes when the temperature changes below a threshold value A position shift of the scanning light to be performed on the scanning surface, and correcting the positional relationship of the scanning light on the scanning surface by the predicted position shift.
An image forming apparatus comprising: a correction control unit. 4. An image forming apparatus having a plurality of scanning optical devices for scanning on an image carrier, wherein a detection mark for detecting a positional relationship on a scanning surface of scanning light emitted from each scanning optical device is provided. A mark detecting means for detecting, and a first position correcting means for calculating a relative positional shift of the scanning light on the scanning surface based on a detection result by the mark detecting means to correct a positional relationship of the scanning light on the scanning surface. A correction control unit, a temperature detection unit installed in or near the scanning optical device, a temperature difference between the scanning optical devices is monitored by the temperature detection unit, and when the temperature change becomes equal to or less than a threshold value, A second correction control unit for predicting a positional shift of the scanning light on the scanning surface corresponding to the temperature difference, and correcting the positional relationship of the scanning light on the scanning surface by the estimated positional shift. Characteristic image forming apparatus. 5. The method according to claim 1, wherein the threshold is a first threshold and the first is
A second threshold having a temperature change or a temperature difference larger than the threshold value of the first threshold value. 5. The method according to claim 3, wherein the correction by the second correction control means is performed when the value exceeds the second threshold value, and the correction by the first correction control means is performed when the value exceeds the second threshold value. An image forming apparatus according to any one of the above.