JPH1035013A - Light quantity control device and method for adjusting light quantity thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To start light quantity controlling of a light emitting element at an adequate timing without delaying image recording operation by a method wherein a time point for starting light quantity controlling of a light quantity control means that controls a driving current applied by a driving means so as to make a light quantity of a light emitting element be a predetermined level is adjusted by an adjusting means. SOLUTION: When a print command is inputted (1), measuring of a waiting time period is finished (2). Judgment is made whether or not the measured waiting time period is within a predetermined time period (3). When the judgment is 'YES', the process is advanced to step (5) or thereafter. When it is 'NO', a determination process of a driving current at the exposing is executed (4). Next, the exposure for forming an image is started (5). When the image forming is completed, measuring of the waiting time period is started by means of a timer (6) and the process is returned to the step (1). When the next printing command is received, the exposure can be executed by using the driving current at the exposing that is determined in the previous printing. As a result, it is possible to immediately advance to the image recording process without executing the exposure controlling operation immediately before the starting of the image recording.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light quantity control device for controlling the light quantity of a light emitting element, particularly a light emitting element such as a semiconductor laser, in an image forming apparatus such as an electronic copying machine or an electrostatic recording apparatus, and the light quantity adjustment of the light quantity control apparatus. It is about the method.

[0002]

2. Description of the Related Art In a laser beam printer, a light emitting element such as a semiconductor laser is being fixed as an exposure element for writing an image corresponding to an input image signal or code data on a photosensitive member.

[0003]

However, the light emission output of the semiconductor laser has a characteristic that greatly varies depending on the environmental temperature. For this reason, the current normally supplied to the semiconductor laser and the light output of the semiconductor laser provided with a photodiode are measured, and an appropriate current value determined based on these is supplied to the semiconductor laser. hand,
Exposure for image formation is performed, and the light amount is controlled so that a constant light amount can be output even when the environmental temperature changes.

However, the above-described exposure for forming an image includes a driving current determining operation for the above-described exposure before the exposure, and thus there is a problem that it takes a long time to complete the image forming operation.

[0005] Further, in the drive current determining operation, the semiconductor laser is made to emit light and the light quantity is measured by the photodiode. Therefore, the laser is irradiated to the photosensitive member, and an optical memory is generated at the irradiated position. In order to eliminate this optical memory, it was necessary to recharge the surface of the photoreceptor before image formation.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the first to sixth inventions according to the present invention to control light intensity of a light emitting element to delay image recording processing. A light quantity control device capable of always and quickly performing image recording based on a stable light quantity at an optimal timing with respect to a light quantity variation peculiar to the light emitting element and with a small number of light quantity control by being started at an appropriate timing; An object of the present invention is to provide a light amount adjustment method for a light amount control device.

[0007]

According to a first aspect of the present invention, there is provided a light emitting element for exposing a light beam based on a recording signal input to an image carrier, and a driving current applied to the light emitting element. Driving means for emitting light, detecting means for detecting the amount of light emitted from the light emitting element, light quantity controlling means for controlling a driving current applied by the driving means so that the light quantity of the light emitting element becomes a predetermined light quantity, and the light quantity control Adjusting means for adjusting the light amount control start timing of the means.

According to a second aspect of the present invention, the adjusting means completes the light quantity control by the light quantity control means before the start of exposure based on the recording signal on the image carrier.

A third invention according to the present invention has a measuring means for measuring an elapsed time after the light quantity adjustment by the light quantity control means is completed, and the measuring means measures the elapsed time when the recording signal is inputted. When the time is within a predetermined time, the driving means applies a driving current based on the stored driving current value to the light emitting element.

According to a fourth aspect of the present invention, the adjusting means includes a light quantity controlling means for controlling the light quantity by the light quantity controlling means when the elapsed time measured by the measuring means at the time of inputting the recording signal exceeds a predetermined time. The control is restarted.

In a fifth aspect according to the present invention, the light amount control means detects the light emitting element of the light emitting element detected by the detection means every time the light emitting means completes exposure based on the recording signal on the image carrier. The drive current value to be applied to the light emitting element is determined so that the light emission amount becomes a predetermined light amount.

According to a sixth aspect of the present invention, there is provided a light emitting element for exposing a light beam based on a recording signal input to an image carrier, a driving means for applying a driving current to the light emitting element to emit light, In a light amount adjusting method of a light amount control device having a detecting unit for detecting a light emitting amount of the light emitting element, a first driving current value applied by the driving unit is determined so that the light amount of the light emitting element becomes a predetermined light amount. A determining step, a measuring step of measuring an elapsed time until the next recording signal input, a recording step of performing image recording based on the drive current value according to the measured elapsed time, and a step of measuring the elapsed time A second determining step of determining a drive current value applied by the drive means so that the light amount of the light emitting element becomes a predetermined light amount according to time.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram illustrating a configuration of an exposure control apparatus according to a first embodiment of the present invention.

In FIG. 1, reference symbol a denotes a light emitting element such as a semiconductor laser, and the amount of emitted light changes according to the drive current. The light beam from the light emitting element a is exposed on the photosensitive member to record an image. b denotes a light amount control unit that changes the light amount of the light beam to be exposed on the photosensitive member from the light emitting element a by controlling, for example, a drive current. Reference numeral c denotes a light amount detection unit constituted by, for example, a photodiode or the like, which detects the light amount of the light emitting element a. d is, for example, RAM, ROM
A suitable driving current for exposure to a photoreceptor, which will be described later, is stored in the storage means. e is, for example, CP
U, RAM, ROM, a control unit including a microprocessor having an input / output control port and the like, and controls the light amount control unit b according to a selection signal.

Hereinafter, the correspondence between this embodiment and each means of the first to fifth inventions and the operation thereof will be described with reference to FIG.

According to a first aspect of the present invention, there is provided a light emitting element a for exposing a light beam based on a recording signal input to an image carrier, and a driving means (light quantity control means) for applying a driving current to the light emitting element a to emit light. b), a detecting means (light amount detecting means c) for detecting the amount of light emitted from the light emitting element a, and the driving means so that the light amount of the light emitting element a becomes a predetermined amount. Light amount control means b for controlling the driving current to be controlled, and adjusting means (control means e) for adjusting the light amount control start timing of the light amount control means b, so that the light amount of the light emitting element a becomes a predetermined light amount. Since the control unit e adjusts the light amount control start timing of the light amount control unit b that controls the drive current applied by the drive unit, the process immediately shifts to the image recording process without performing exposure control immediately before the start of image recording. Door can be.

According to a second aspect of the present invention, the adjusting means (control means e) includes the image carrier (photosensitive drum 1 (FIG.
Since the light amount control by the light amount control means b is completed before the start of the exposure based on the recording signal, the image recording process can be started simultaneously with the input of the recording signal, and the first print time can be reduced. .

According to a third aspect of the present invention, there is provided a measuring means (a timer circuit in the control means e) for measuring an elapsed time after the completion of the light quantity adjustment by the light quantity control means b, and the timer circuit measures the time when the recording signal is inputted. When the elapsed time is within a predetermined time (1 hour in the present embodiment), the driving unit applies a driving current based on the driving current value stored in the storage unit d to the light emitting element a. Therefore, the image recording process can be started simultaneously with the input of the recording signal during the period in which the light quantity fluctuation does not occur.

According to a fourth aspect of the present invention, when the elapsed time measured by the timer circuit at the time of input of the recording signal exceeds a predetermined time, the adjusting means (control means e) controls the light quantity control means b. Since the light quantity control is restarted, when the light quantity fluctuation has occurred, normal light quantity control can be executed to start image recording with the optimal light quantity.

According to a fifth aspect of the present invention, the light quantity control means b detects the light emitting element a detected by the light quantity detection means c every time the light emitting element a completes exposure based on the recording signal on the image carrier. Since the drive current value to be applied to the light emitting element a is determined and stored in the storage means d so that the light emission amount becomes a predetermined light amount, image recording based on a recording signal without delaying image recording is optimal. Since the light amount control is performed at an appropriate timing, the image recording can be started immediately with the optimal light amount at the next image recording.

FIG. 2 is a flowchart showing an example of a procedure for determining a drive current at the time of exposure of the exposure control apparatus according to the present invention. In addition, (1) to (5) indicate each step.

First, the drive current is gradually increased and applied to the light emitting element a (1), and at the same time, the light quantity of the light emitting element a is measured by the light quantity detecting means c (2). And
It is determined whether the light amount of the light emitting element a has reached an appropriate light amount set in advance (3), and if NO, step (1) is performed.
Returning to YES, if YES, the drive current value when the light amount of the light emitting element a reaches the preset appropriate light amount is measured, and the determined drive current value is stored in the storage means d (4). . Then, the driving current stored by the light quantity control means b controlled by the control means e is supplied to the light emitting element a, and exposure for image formation is started (5).

FIG. 3 is a sectional view of an essential part showing an example of an image forming apparatus to which the present invention can be applied.

In FIG. 1, reference numeral 1 denotes a photosensitive drum, which is, for example, an OPC photosensitive drum having a diameter of 30 mm and is uniformly charged to -700 V by a charging roller 2. Next, an electrostatic latent image is formed on the photosensitive drum 1 by the laser beam 3 modulated by the image signal by the exposure control device shown in FIG. Then, a negative toner is supplied to the latent image in the developing unit 4 to form a toner image T on the surface of the photosensitive drum 1.

When the transfer material S arrives at the transfer site, a positive transfer bias is applied to the transfer roller 5, and the toner image T is transferred to the transfer material S. After transferring the toner image to the transfer material S, the transfer material S passes over a transport guide (not shown), and the toner image is fixed on the transfer material as a permanent fixed image in a fixing device (not shown). Reference numeral 6 denotes a cleaner for removing residual toner on the photosensitive drum.

Here, a light emitting element a such as a semiconductor laser
The light emission output greatly varies depending on the environmental temperature, but this factor does not change in a short time. Even if the environmental temperature condition is suddenly changed, it takes time for the temperature of the light emitting element a itself to change. Therefore, the light amount control shown in FIG. 1 is executed every elapse of a predetermined time.

FIG. 4 is a flowchart showing an example of a light quantity control procedure of the light quantity control device according to the first embodiment of the present invention. Note that (1) to (6) indicate each step.

First, when a print command is input (1), the measurement of the waiting time is terminated (2), and whether or not the measured waiting time is within a preset fixed time (1 hour in the present embodiment). Is determined (3), and if YES, the process proceeds to step (5) and thereafter, and if NO, a drive current determination process during exposure (see FIG. 2) is executed (4).

Next, exposure for image formation is started (5), and when image formation is completed, measurement of a waiting time is started by a timer (not shown) (6), and the process returns to step (1).

As described above, when the next print command is received within a predetermined waiting time, for example, within one hour, the drive current determining operation at the time of exposure is not performed, and the exposure current determined at the time of the previous print is not performed. Exposure for image formation is performed using the drive current. By doing so, the time required for printing can be reduced, and the optical memory of the photosensitive drum 1 can be prevented from being used in the drive current determination operation.

When a print command is received after a certain period of time, a drive current determining operation at the time of exposure is performed.
Exposure for image formation is performed. In this case, the operation of determining the drive current at the time of exposure and the operation of eliminating the trace irradiated on the photosensitive drum 1 at that time, for example, charging the photosensitive drum 1 uniformly again by the charging roller 2 for another round, etc. Therefore, the time required for normal printing is longer.

[Second Embodiment] FIG. 5 is a flowchart showing an example of a light quantity control procedure of a light quantity control device according to a second embodiment of the present invention. Note that (1) to (4) show each step.

First, when the power is turned on, the drive current determining process shown in FIG. 2 is executed (1). Next, when a print command is input (2), exposure for image formation is started (3), and image recording is performed. Next, after the end of the exposure, the drive current for the next exposure is determined (4), and the process returns to the step (2).

First, a drive current determining operation to be given at the time of exposure for image formation is determined in advance when the power is turned on (1), and a print command (2) starts to supply a drive current to the light emitting element a. After the print command, the exposure operation for image formation is performed without performing the drive current determination operation given at the time of exposure for image formation (3). After the exposure for image formation is completed, a drive current determining operation to be performed at the time of exposure for image formation in the next print operation is performed (4), and the process returns to step (2) to issue a next print command. Then, an exposure operation for image formation is performed using the drive current.

In the optical memory of the photosensitive drum 1 by the drive current determining operation, after an image is formed by the above-described image forming apparatus, for example, the photosensitive drum 1 is uniformly charged again by the charging roller 2 for another round. The optical memory is eliminated.

As a result, although the operation time of the exposure device is not shortened much, the time from receiving the print command to discharging the paper can be shortened, and the optical memory of the photosensitive drum 1 due to the drive current determination operation can be prevented. it can.

When a print command is issued after the end of the exposure operation, before or during the drive current determination operation for exposure, the drive current determination operation for exposure is stopped and the drive current for exposure is changed to the previous one. The next print operation may be started with the same drive current as that determined during the operation.

Third Embodiment In the above embodiment, the interval between two print commands is, for example, one day.
When the length is extremely long, there is a possibility that an image defect occurs due to a large difference between the time of determining the drive current at the time of exposure for image formation and the time of exposure for image formation. Therefore, if a print command is issued after a certain period of waiting time has elapsed after the image formation is completed, before the exposure operation for the image formation starts, A drive current re-determining operation may be performed, and the control may be performed such that the drive current is re-determined before the exposure operation for image formation starts. Less than,
The embodiment will be described.

FIG. 6 is a flowchart showing an example of a light quantity control procedure of the light quantity control device according to the third embodiment of the present invention. (1) to (8) indicate each step.

First, when the power is turned on, the drive current determining process shown in FIG. 2 is executed (1). Next, the measurement of the waiting time is started by a timer (not shown) (2), and when a print command is input (3), the measurement of the waiting time is terminated (4). Next, it is determined whether or not the measured time is within a predetermined time (5). If NO, the process proceeds to step (6),
The drive current at the time of exposure is re-determined according to the procedure shown in FIG. 2, and the process proceeds to step (7).

On the other hand, if YES in step (5), exposure for image formation is started (7), and after completion of exposure, a drive current for the next exposure is determined (8). Return to (3).

As described above, a good image can be obtained by determining the drive current at the time of exposure for image formation.

In the above-described embodiment, the drive current determining operation at the time of exposure for image formation is performed even when the drive determination operation at the time of exposure for image formation is performed and after the image formation is completed. , The drive current for the next page is determined, but this is omitted, a drive current determination operation for exposure for image formation is performed before exposure for image formation, and the determined drive current is used for the next page. May be determined.

Hereinafter, the correspondence between this embodiment and each step of the sixth invention and the operation thereof will be described with reference to FIGS. 2, 4 to 6 and the like.

According to a sixth aspect of the present invention, there is provided a light emitting element a for exposing a light beam based on a recording signal inputted on an image carrier, a driving means for applying a driving current to the light emitting element a to emit light, In the light amount adjusting method of the light amount control device having the light amount detecting means c for detecting the light emitting amount of the element a, a driving current value applied by the driving means is determined so that the light amount of the light emitting element a becomes a predetermined light amount. 1 (steps (1) to (4) in FIG. 2, FIG. 5 and step (1) in FIG. 6), and a measuring step (step (FIG. 4) in FIG. 2), (6), steps (2), (4) in FIG. 6) and a recording step (step (5) in FIG. 4) for performing image recording based on the drive current value according to the measured elapsed time. ), Step (7) in FIG. 6)
And a second determining step of determining a driving current value applied by the driving means so that the light amount of the light emitting element becomes a predetermined light amount according to the measured elapsed time (step (4) in FIG. 4, Step (6) in FIG. 6) is executed by the control means e based on a control program stored in a memory (not shown), so that the process immediately shifts to image recording processing without performing exposure control immediately before the start of image recording. In addition, since the light quantity control is performed at an optimal timing when the image recording based on the recording signal that does not delay the image recording is completed, the image recording can be started immediately with the optimal light quantity at the next image recording.

[0047]

As described above, the first embodiment according to the present invention is described.
According to the invention, the adjusting unit adjusts the light amount control start timing of the light amount control unit that controls the drive current applied by the driving unit so that the light amount of the light emitting element becomes the predetermined light amount. Without performing exposure control,
It is possible to promptly shift to the image recording process.

According to the second aspect, the adjusting means is arranged to start the exposure before starting the exposure based on the recording signal on the image carrier.
Since the light quantity control by the light quantity control means is completed, the image recording process can be started simultaneously with the input of the recording signal, and the first print time can be reduced.

According to the third aspect, when the elapsed time measured by the measuring means at the time of inputting the recording signal is within a predetermined time, the driving means stores the driving data stored in the storage means. Since the driving current based on the current value is applied to the light emitting element, the image recording process can be started simultaneously with the input of the recording signal during the period in which the light quantity fluctuation does not occur.

According to the fourth invention, when the elapsed time measured by the measuring means at the time of inputting the recording signal exceeds a predetermined time, the adjusting means controls the light quantity by the light quantity controlling means. Since the light amount is restarted, when light amount fluctuations occur, normal light amount control can be executed to start image recording with an optimum light amount.

According to the fifth invention, the light amount control means is configured to detect the light emission amount of the light emitting element detected by the detection means every time the light emitting means completes exposure based on the recording signal on the image carrier. Since the drive current value to be applied to the light emitting element is determined and stored in the storage unit so that the light amount becomes a predetermined light amount, the image recording based on the recording signal without delaying the image recording is performed at the optimal timing. Since the light amount control is performed, the image recording can be started immediately with the optimum light amount at the next image recording.

According to the sixth aspect, the drive current value applied by the drive means is determined so that the light quantity of the light emitting element becomes a predetermined light quantity, and the determined drive current value is registered in a memory. Measuring the elapsed time until the next recording signal input, recording an image based on the drive current value registered in the memory in accordance with the measured elapsed time, and measuring the measured elapsed time. A drive current value applied by the drive unit is determined so that the light amount of the light emitting element becomes a predetermined light amount according to time, and the determined drive current value is re-registered in a memory. To control the light amount at the optimal timing when the image recording based on the recording signal that does not delay the image recording can be quickly performed without performing the exposure control and the image recording process can be performed without delaying the image recording process. You can quickly start image recording at the optimum light amount at the time of the next image recording.

Accordingly, an effect is obtained such that an image can be quickly and always recorded based on a stable light amount at an optimal timing with respect to the light amount fluctuation peculiar to the light emitting element and with a small number of light amount control operations.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an exposure control device according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating an example of a procedure of a drive current determining process at the time of exposure of an exposure control device according to the present invention.

FIG. 3 is a sectional view of a main part showing an example of an image forming apparatus to which the present invention can be applied.

FIG. 4 is a flowchart illustrating an example of a light amount control procedure of the light amount control device according to the first embodiment of the present invention.

FIG. 5 is a flowchart illustrating an example of a light amount control procedure of a light amount control device according to a second embodiment of the present invention.

FIG. 6 is a flowchart illustrating an example of a light amount control procedure of a light amount control device according to a third embodiment of the present invention.

[Explanation of symbols]

 a light emitting element b light quantity control means c light quantity detection means d storage means e control means

Claims (6)

[Claims] 1. A light emitting element for exposing a light beam based on a recording signal input to an image carrier, a driving unit for applying a driving current to the light emitting element to emit light, and detecting a light emission amount of the light emitting element. Detecting means for controlling the driving current applied by the driving means so that the light quantity of the light emitting element becomes a predetermined light quantity, and adjusting means for adjusting a light quantity control start timing of the light quantity controlling means. A light quantity control device characterized by the above-mentioned. 2. The light quantity control device according to claim 1, wherein the adjustment means completes the light quantity control by the light quantity control means before the start of exposure based on the recording signal on the image carrier. . And a measuring means for measuring an elapsed time after the light quantity adjustment by the light quantity controlling means is completed, wherein the elapsed time measured by the measuring means at the time of inputting the recording signal is within a predetermined time. 2. The light amount control device according to claim 1, wherein the driving unit applies a driving current based on a stored driving current value to the light emitting element. 4. The light quantity control by the light quantity control means when the elapsed time measured by the measurement means at the time of input of the recording signal exceeds a predetermined time. The light quantity control device according to claim 3. 5. The light amount control unit controls the light emission amount of the light emitting element detected by the detection unit to become a predetermined light amount every time exposure of the light emitting unit on the image carrier based on the recording signal is completed. 2. The light amount control device according to claim 1, wherein a drive current value to be applied to the light emitting element is determined. 6. A light emitting element for exposing a light beam based on a recording signal input to an image carrier, a driving unit for applying a driving current to the light emitting element to emit light, and detecting a light emission amount of the light emitting element. A light amount adjusting method of the light amount control device having a detecting unit that performs a first determining step of determining a driving current value applied by the driving unit so that the light amount of the light emitting element becomes a predetermined light amount;
A measuring step of measuring an elapsed time until the next recording signal input, a recording step of performing image recording based on the drive current value in accordance with the measured elapsed time, and a measuring step in accordance with the measured elapsed time A second determining step of determining a drive current value to be applied by the driving means so that the light amount of the light emitting element becomes a predetermined light amount.