JPH0561324A - Controller for laser power - Google Patents

Abstract

PURPOSE:To automatically adjust laser power in a laser power controller having plural recording density, to enhance working efficiency and to reduce the cost of the device. CONSTITUTION:In the laser power controller which controls a semiconductor laser 103 outputting a laser beam corresponding to the plural recording density, a CPU 101 which controls the driving voltage value of the laser 103 and sets the threshold of the output level of the laser 103 and an LD driver 10(a comparator 106) which monitors the driving voltage of the laser 103 are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser power control device which uses a laser beam as a light source and is used in a laser printer, a digital copying machine, a facsimile and the like, and more specifically, an optical writing device having a plurality of recording densities. To a laser power control device capable of automatically setting the laser beam power of the above so as to correspond to each recording density.

[0002]

2. Description of the Related Art Conventionally, one laser writing device has a plurality of recording densities (for example, 240 DPI, 300 DPI, 400 D).
The power of the laser beam corresponding to PI, ...) Was adjusted by an external VR (variable resistor).
For example, an external VR (variable resistor) is used to adjust the output value of the semiconductor laser corresponding to each recording density as shown in FIG.

[0003]

However, in the laser power control device as described above, the output value of the semiconductor laser adapted to each recording density is set as an external V.
Since the adjustment is performed by R (variable resistance), there is a problem that the adjustment work becomes complicated, the work efficiency is reduced, and the cost of the device is increased.

The present invention has been made in view of the above, and in a laser power control device having a plurality of recording densities, the laser power is automatically adjusted to improve work efficiency and reduce the cost of the device. The purpose is to plan.

[0005]

In order to achieve the above object, the present invention provides a laser power control device for controlling laser output means for outputting a laser beam corresponding to a plurality of recording densities. To provide a laser power control device including control means for controlling the drive voltage value of the laser output means and setting a threshold value of the output level of the laser output means, and monitor means for monitoring the drive voltage of the laser output means. Is.

Further, it is desirable that the drive voltage value is raised above the threshold value and constant control is performed when a predetermined voltage value with respect to the recording density is reached.

Further, it is desirable that the drive voltage value is raised above the threshold value to reach a predetermined voltage value with respect to the recording density, and then the voltage value is shifted downward or upward for constant control.

[0008]

The laser power control apparatus according to the present invention controls the drive voltage value of the laser output means in the laser power control apparatus for controlling the laser output means for outputting the laser beam corresponding to a plurality of recording densities. The threshold of the output level of the output means is set, and the drive voltage of the laser output means is monitored.

Further, the drive voltage value is raised above the threshold value, and constant control is performed when a predetermined voltage value with respect to the recording density is reached.

Further, after the drive voltage value is raised above the threshold value and reaches a predetermined voltage value with respect to the recording density, the voltage value is shifted downward or upward to perform constant control.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing the main configuration of a laser power control device according to the present invention. In the figure, 1
01 is a C for executing various controls of the laser power control device
PU (microcomputer), 102 is an LD driver that drives and controls the semiconductor laser 103, 103 is a semiconductor laser (LD) that outputs a laser beam, and 104 is a semiconductor laser (LD) 103 incorporated in the LD driver 102.
VR (variable resistance) that changes the output value of
A U / D built-in D / A converter and 106 are LD driver built-in comparators. DA1 (for coarse adjustment) and DA2 (for fine adjustment) in the figure are semiconductor lasers 103.
Is a voltage value for driving the D / A converter 105 and receives a control signal from the CPU 101 and is output from the D / A converter 105. DATA
Indicates image data for forming an image by turning on / off the semiconductor laser (LD) 103, and CO indicates the LD driver 1
02 is the output from the built-in comparator 106,
The VR (variable resistance) 104 determines the threshold value based on the O output. MO is a monitor output of the drive voltage of the semiconductor laser (LD) 103 and monitors the drive voltage in an analog manner.

In the above description, the monitor output CO of the comparator 106 is "H" when the driving voltage of the semiconductor laser (LD) 103 is 2V or more when it is 240 DPI, and "L" when the driving voltage is 2V or less. Output.

FIG. 2 is a flow chart showing an example of the operation of setting the output level of the laser beam according to the present invention above the target value. First, it is confirmed whether or not the initial value is set (S201). If the initial value is not set, DA1 = 1V is set (S202). Next, it is confirmed whether the monitor output CO of the comparator 106 is CO = “H” (S203), and if CO = “H”, DA1 is updated (S204), and the process returns to step S203. When CO = “H”, the recording density (DP
I) is confirmed (S205), and if it is 240 DPI, normal control is executed and the process is terminated (S206). When it is 300 DPI, it is confirmed whether or not the analog monitor output MO is MO ≧ 3 V (S207). When the analog monitor output MO is MO ≧ 3 V, the normal control is executed similarly to 240 DPI and the process ends. If MO ≧ 3V, DA1 is updated (S208) and the process returns to step S207. Also,
At 400 DPI, the analog monitor output MO is M
It is confirmed whether or not O ≧ 4V (S209). If the analog monitor output MO is MO ≧ 4V, the normal control is executed as it is, and the process is terminated (S210). If MO ≧ 4V, DA1 is updated (S211), and step S20 is performed.
Return to 9.

FIG. 3 is an explanatory diagram showing the output level of the laser beam obtained by the operation example of FIG.
An example is shown in which the output level of the laser beam at DPI is set higher than the target value. A in the figure is 240 DPI
The threshold value of the monitor output CO of the comparator 106 at the time, and b indicates the analog monitor output MO at the time of 300 DPI.

FIG. 4 is a flow chart showing an example of the operation of setting the output level of the laser beam below the target value according to the present invention. First, it is confirmed whether or not the initial value is set (S401), and if the initial value is not set, DA1 = 1V is set (S402). Next, it is confirmed whether or not the monitor output CO of the comparator 106 is CO = “H” (S403), and if CO = “H”, DA1 is UP (S404) and the process returns to step S403. When CO = “H”, the recording density (DP
I) is confirmed (S405), and if it is 240 DPI, the output level is made constant and then 1 LSB is subtracted from DA1 to make the output level constant at a level lower than the target value (S40).
6).

In step S405, when the recording density is 300 DPI, the analog monitor output MO
Is MO ≧ 3V (S407), and if the analog monitor output MO is MO ≧ 3V, 240 DPI
After setting the output level to the same level as above, 1 LSB from DA1
Pull down to make the output level constant at a level lower than the target value and end. If MO ≧ 3V, DA1 is updated (S408), and the process returns to step S407.

In step S405, when the recording density is 400 DPI, the analog monitor output MO
Is MO ≧ 4V (S409). If the analog monitor output MO is MO ≧ 4V, 240DPI.
After setting the output level to the same level as above, 1 LSB from DA1
Pull down to make the output level constant at a level lower than the target value and end. If MO ≧ 4V, DA1 is updated (S410) and the process returns to step S409.

FIG. 5 is an explanatory diagram showing the output level of the laser beam obtained by the operation example of FIG.
An example is shown in which the output level of the laser beam at DPI is set below the target value.

FIG. 6 is a flowchart showing an operation example in which the output level of the laser beam according to the present invention is set above the target value by fine adjustment. Here, the output D of the D / A converter 105 for finely adjusting the drive voltage of the laser beam
Add A2. First, it is confirmed whether or not the initial value is set (S601). If the initial value is not set, DA1 = 0.5V and DA2 = 0.5V are set (S602). Next, it is confirmed whether the monitor output CO of the comparator 106 is CO = “H” (S60
3) If not CO = "H", DA1 is updated (S60
4) and returns to step S603. On the contrary, CO = “H”
In case of, the recording density (DPI) is confirmed (S60
5) If it is 240 DPI, DOWN DA2 (S
606), and confirm whether the CO output is "L" (S
607), if CO = “L”, DA2 + 1 is set (S
608).

When the recording density is 300 DPI in step S605, it is confirmed whether or not the analog monitor output MO is MO ≧ 3 V (S609), and MO ≧
If it is not 3 V, DA1 is updated (S610) and the process returns to step S609. Analog monitor output MO is MO ≧ 3V
If so, DA2 is DOWN (S611), and it is confirmed whether the analog monitor output MO is MO <3V (S).
612), if MO <3V, DA2 + 1 is set (S6).
08). If MO <3V, step S611
Return to.

At 400 DPI, it is confirmed whether or not the analog monitor output MO is MO ≧ 4 V (S
613), if MO ≧ 4V, UP DA1 (S6
14) and returns to step S613. If the analog monitor output MO is MO ≧ 4V, DOWN DA2 (S6
15) Further, it is confirmed whether or not the analog monitor output MO is MO <4V (S616), and if MO <4V, DA2 + 1 is set (S608). If MO <4V, the process returns to step S615.

FIG. 7 is an explanatory diagram showing the output level of the laser beam obtained by the operation example of FIG.
An example is shown in which the output level of the laser beam at DPI is finely adjusted and set above the target value.

FIG. 8 is a flow chart showing an example of the operation of finely adjusting the output level of the laser beam below the target value according to the present invention. Here, the output DA2 of the D / A converter that finely adjusts the drive voltage of the laser beam is added. First, it is confirmed whether or not the initial value is set (S801). If the initial value is not set, D
Set A1 = 0.5V and DA2 = 0.5V (S8
02). Next, it is confirmed whether the monitor output CO of the comparator 106 is CO = “H” (S803), and CO
If it is not "H", DA1 is updated (S804) and the process returns to step S803. When CO = “H”,
Check the recording density (DPI) (S805), 240DP
If I, DA2 is made DOWN (S806), it is confirmed whether the CO output is "L" (S807), and CO =
If it is "L", the process ends.

In step S805, when the recording density is 300 DPI, it is confirmed whether the analog monitor output MO is MO ≧ 3 V (S808), and MO ≧
If it is not 3 V, DA1 is updated (S809) and the process returns to step S808. Analog monitor output MO is MO ≧ 3V
If so, DA2 is DOWN (S810) and it is confirmed whether or not the analog monitor output MO is MO <3V (S
811), if MO <3V, the process ends. On the contrary, if MO <3V, the process returns to step S810.

At 400 DPI, it is confirmed whether the analog monitor output MO is MO ≧ 4 V (S
812), and if MO ≧ 4V, UP DA1 (S8
13) and returns to step S812. If the analog monitor output MO is MO ≧ 4V, DOWN DA2 (S8
14) Further, it is confirmed whether or not the analog monitor output MO is MO <4V (S815), and if MO <4V, the process is ended. On the contrary, if MO <4V, the process returns to step S814.

FIG. 9 is an explanatory diagram showing the output level of the laser beam obtained by the operation example of FIG.
An example is shown in which the output level of the laser beam at the time of DPI is finely adjusted and set below the target value.

With the configuration and operation described above, it becomes possible to automatically set the laser power of the semiconductor laser (LD) 103 corresponding to the recording density without depending on the external VR (variable resistance). Also, a semiconductor laser (LD) 1
The output level of the laser power can be accurately controlled according to the output characteristics of the optical disc 03, the characteristics of the optical writing device and the image process, and the stability of the quality of the entire apparatus can be improved.

[0028]

As described above, according to the laser power control device of the present invention, in the laser power control device for controlling the laser output means for outputting the laser beam corresponding to a plurality of recording densities, A laser having a plurality of recording densities, since it comprises a control means for controlling the drive voltage value and setting a threshold of the output level of the laser output means, and a monitor means for monitoring the drive voltage of the laser output means. It is possible to automatically adjust the laser power in the power control device, improve work efficiency, and reduce the cost of the device.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main configuration of a laser power control device according to the present invention.

FIG. 2 is a flowchart showing an operation example of setting an output level of a laser beam to a value higher than a target value according to the present invention.

FIG. 3 is a graph showing an output level of a laser beam obtained by the operation example of FIG.

FIG. 4 is a flowchart showing an operation example of setting an output level of a laser beam to be lower than a target value according to the present invention.

5 is a graph showing an output level of a laser beam obtained by the operation example of FIG.

FIG. 6 is a flowchart showing an operation example in which the output level of the laser beam according to the present invention is finely adjusted to be higher than the target value.

7 is a graph showing an output level of a laser beam obtained by the operation example of FIG.

FIG. 8 is a flowchart showing an operation example of finely adjusting the output level of the laser beam below the target value according to the present invention.

9 is a graph showing an output level of a laser beam obtained by the operation example of FIG.

FIG. 10 is a graph showing an example of laser power control according to a conventional example.

[Explanation of symbols]

 101 CPU 102 LD Driver 103 Semiconductor Laser (LD) 104 VR (Variable Resistance) 105 D / A Converter 106 Comparator

Claims (3)

[Claims] 1. A laser power control device for controlling a laser output means for outputting a laser beam corresponding to a plurality of recording densities, wherein a drive voltage value of the laser output means is controlled, and an output level of the laser output means. 2. A laser power control device comprising: a control unit that sets the threshold value of 1. and a monitor unit that monitors the drive voltage of the laser output unit. 2. The laser power control device according to claim 1, wherein the drive voltage value is raised above the threshold value, and constant control is performed when a predetermined voltage value with respect to the recording density is reached. 3. The driving voltage value is raised from the threshold value to reach a predetermined voltage value with respect to the recording density, and then the voltage value is shifted down or up for constant control. 1. The laser power control device according to 1.