JPH02265762A - Light quantity controller - Google Patents

Abstract

PURPOSE:To shorten a period of time until the quantity of an emitting light reaches a predetermined value by providing nonvolatile memory means for storing in advance control information at the time of previous control, and setting a control starting value based on the stored information. CONSTITUTION:A monitor signal is controlled by an operational amplifier 19B and a comparator 19D at the outputs to approach a light emitting power to a predetermined value, an enable signal of an enable signal generator 26 is set from a H level to a L level, and a power setting operation is finished. Information corresponding to the output value of a D/A converter 21B at the time of power setting is stored previously in a nonvolatile memory 21E, the information is read at the time of starting of setting power, and a control starting value is set. Accordingly, since a period of time required for setting power can be largely shortened, the life of a laser diode can be extended, and it can prevent a photosensor from deteriorating. Further a working load of a CPU can be reduced, and using efficiency can be enhance.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a light amount control device for a laser diode in a laser printer.

(Prior Art) First, the schematic structure and operation of a laser printer in which the present invention is implemented will be described with reference to FIG.

Recording paper 2 fed in the direction of arrow A from paper feeding device 1 is timed by a pair of registration rollers 3 and is transported to a latent image carrier consisting of a drum-shaped photoreceptor 4. The photoreceptor 4 is rotationally driven in a counterclockwise direction, the surface of which is charged by a wit charger 5, and laser light is irradiated from a laser optical system 6 to form an electrostatic latent image on the photoreceptor. This latent image is made visible by toner when passing through the developing device 7, and this visible image is transferred by the transfer charger 8 to the recording paper 2 conveyed to the photoreceptor 4, and the visible image on the transferred recording paper is is fixed by the fixing bag M9.

Then, the recording paper 2 that has left the fixing device is discharged to the paper discharge section 11 in the direction of arrow B. On the other hand, residual toner is removed from the photoreceptor 4 after the visible image has been transferred by a cleaning device having a cleaning blade 12 .

The toner removed from the photoconductor is stored in a toner recovery tank 13.
will be collected. Note that 10 is a printer body, 14 is a controller, and 15 is a print control section.

FIG. 3 shows an outline of the laser control system in the laser printer described above. The controller 14 of the printer main body 10 is connected to the host computer 16, and the print data sent from the host computer 16 is sent to the controller 14 as a video signal. and print control unit 1
Sent to 5. This print control section 15 includes a CPU 15
A. It is composed of a power adjustment section 21 and a gate signal generation section 22. The power adjustment section 21 adjusts the laser diode 20 of the laser optical system 6 to 0N10FF according to the video signal.
As shown in FIG. 4, the laser beam is irradiated and deflected on each side of the deflector 17 consisting of a rotating polygon mirror, and the laser beam is scanned (main scanning) on the photoreceptor 4, and a static image is formed on the photoreceptor. !
A latent image is formed.

Further, the synchronization detection section 18 generates a synchronization detection signal once for each -line scan, and sends it to the gate signal generation section 22 to control the power set (light emission start timing) of the video signal. Further, the power monitor section 19 monitors the light emission of the laser diode 20. In other words, even if the current flowing through the laser diode is constant, the emitted light power of the laser diode changes over time and varies between individual diodes, so the power is not constant, and it is difficult to obtain a stable image. Control is required to keep the light emitting power constant.

Conventionally, a D/A converter has been mainly used for control to keep the light emission power constant.

(For example, JP-A-59-147568, JP-A-6
(See Publication No. 0-120663) (Problems to be Solved by the Invention) However, in this type of light amount control device, the input of the D/A converter is a hard counter output.

The hard counter is cleared when the power is turned on, so the amount of emitted light starts from a low level, so it takes time for the amount of emitted light to reach a predetermined value.

If it takes a long time like this, the laser diode will turn on for that amount of time, exposing the photoreceptor and causing fatigue.
Another problem is that the life of the laser diode is shortened.

In addition, there are devices that control the input of the D/A converter by the CPU;
Since the PU controls the amount of light, other work cannot be done, and the CPU
There was a problem that the usage efficiency of the system decreased.

The present invention solves the problems of the prior art described above, and aims to provide a light amount control device that shortens the time (power set time) until the amount of emitted light reaches a predetermined value. be.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a light emitting means, a detecting means for detecting the amount of light emitted from the light emitting means, and an amount of light emitted from the light emitting means according to the output of the detecting means. control means for controlling to a constant value, and non-volatile storage means for storing control information from the previous control in advance, and a control start value of the control means immediately after power-on is set based on the stored information in the non-volatile storage means. This is what you set.

(Function) When the amount of emitted light is a predetermined value, the current ILO flowing through the laser diode is unique to each laser diode, and its value does not change significantly even if the power is turned off. The invention focused on this point and set the control information corresponding to the ILD (corresponding to the input of the D/A converter) when the power was last set to the 0N10 F F of the power supply.
Regardless of the value, store it in the storage device and start from that value when starting the power set. This greatly reduces power set time.

(Example) An embodiment will be described in detail below with reference to one drawing.

FIG. 1 shows an embodiment of the present invention, in which the laser power adjustment section 21 includes a CPU 21A, a D/A converter 21
B, an operational amplifier 21C, a transistor 210, and a nonvolatile memory 21E. The D/A converter 21B is controlled by the CPU 21A, and the nonvolatile memory 21E
It is also controlled by the CPU 21A. Non-volatile memory 21
E is the D/A converter 2J from the previous power set.
Information corresponding to the output value of B is stored.

Further, a power set start signal is output from the CPU 21A.

The power monitor section 19 includes a bin photodiode 19A that is in contact with the laser diode 20 and monitors its power.
, an operational amplifier 19B, a comparator 190, and a volume 19C for adjusting the laser power to a predetermined value.

24 is a NOR gate, which takes the logical sum of the laser diode signal and the video signal, and connects the laser diode 20 to 0N1.
0FF. Reference numeral 25 denotes a termination signal generating section, which generates this termination signal (
5e) is output when the monitor signal (FIG. 5d) changes from L level to H level (d□). Reference numeral 26 denotes an enable signal generating section which changes the laser diode signal (FIG. 5f) and enable signal (FIG. 5g) from L level to H level when the gate signal (FIG. 5b) changes from L level to H level. level (fz)t(g'z) to cause the laser diode 20 to emit light (ON state), and when the gate signal changes from H level to L level (b,), the laser diode signal changes from H level to It is set to L level (f2) to stop the laser diode 20 from emitting light (OFF state).

Next, the operation will be described. First, in response to the power set start signal (FIG. 5C) from the CPU 21A, an enable signal (FIG. 5g) and a laser diode signal (FIG. 5f) are sent from the enable signal generator 26 to the UP/D of the CPU 21A.
The signal is input to an OWN counter section (not shown). On the other hand, the gate signal generation section 22 receives the synchronization detection signal (FIG. 5a) from the synchronization detection section 18 of FIG. A gate signal (FIG. 5b) indicating the timing on the photoreceptor 4 is output. Therefore, the rising edge b of this gate signal, (
(H level), the enable signal g becomes H level, and the counter section becomes enabled. Here, if the monitor signal (FIG. 5d) is at H level, the counter section counts down in synchronization with the clock signal CK, and if the monitor signal is at L level, it counts up. The output of this counter section is input to the D/A converter 21B,
When the counter section counts down, the output current of the D/A converter becomes smaller, and the output current is reduced by the operational amplifier 21C and the transistor 210.

The current of the laser diode 20 is increased to increase the light emission power. Similarly, when the counter section counts up, the light emission power is decreased. In this way, the monitor signal (FIG. 5d) detected by the pin photodiode 1.9A is input to the CPU 21A and the termination signal generating section 25.

The output of the monitor signal is controlled by the operational amplifier 19B and the comparator 190 so that it is output as an H level if it is lower than a predetermined value adjusted by the volume 19C, and as an L level if it is higher than the predetermined value. In this way, the emission power approaches a predetermined value.

When the monitor signal changes from L level to H level (5th
The termination signal (Fig. 5 e) is generated in Fig. 5 (d), and the enable signal (Fig. 5 g) of the enable signal generating section 26 is changed from the H level to the L level (Fig. 5 g 2).

The power set operation ends.

Here, the operational amplifier 19B in the power monitor section 19
Let the output be vte. In the conventional configuration, since the counter at the input section of the D/A converter 21B is cleared when the power is turned on, vI9 starts from a low value, as shown in FIG. 7(a).

8 In the present invention, it took a long time t1 to complete the power set, information corresponding to the output value of the D/A converter 21B at the time of the previous power set is stored in advance in the nonvolatile memory 21H, and the power set is At the start of the process, the information is read and the control start value is set.

That is, as shown in FIG. 6, the power is turned on.

■When power set starts, ■CPU 21A reads the output value to D/A converter 21B during the previous power set from nonvolatile memory 21E and outputs it to D/A converter 21B, and also outputs ■power set start signal. . ■If the monitor signal is at H level, it is assumed that the amount of light emitted from the laser diode 20 is less than the predetermined value.
■The output to the D/A converter 21B is -1, and ■If the monitor signal is at L level, it is assumed that the amount of light emitted from the laser diode 20 is greater than a predetermined value, and ■The output to the D/A converter 21B is +1. . Thereafter, the value output to the D/A converter 21B is stored in the nonvolatile memory 21H. When the monitor signal goes from L level to H level, ■
Assuming that the power set is completed, return to ■; if the power set is not completed, return to ■.

In this embodiment configured in this way, the nonvolatile memory 2
Since the power set starts from the output value to the D/A converter 21B at the time of the previous power set stored in 1H, it is shown in FIG. 7(b). like.

The value of vte reaches the predetermined value in a short time 1, /, thus the power set time is significantly shortened.

(Effects of the Invention) As explained above, according to the present invention, the time required for power setting can be significantly shortened, so the lighting time of the laser diode during that time can be shortened.

It is possible to extend the life of the laser diode and prevent deterioration of the photoreceptor. Furthermore, the workload on the CPU can be reduced and usage efficiency can be increased.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of laser emission and light emission amount control according to an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a laser printer in which the present invention is implemented, and FIG. 3 is a laser control system in the laser printer. FIG. 4 is a block diagram showing the schematic configuration of
A schematic configuration diagram of a laser optical system in a laser printer, FIG. 5 is a timing chart of signals of each part in FIG. 1, and FIG.
The diagram is. The flowchart of the power set operation, FIG. 7(a), is as follows:
A diagram showing the power set time in the conventional example, Fig. 7 (b
) is a diagram showing power set time in the present invention. 19...Power monitor section, 19A...Pin photodiode, 19B...Operation amplifier, 19D...
・Comparator, 20...Laser diode,
21...Laser power adjustment section, 21A...CPU
, 21B...D/A converter, 21G...operational amplifier, 210...transistor, 21E...
Non-volatile memory, 22... gate signal generation section, 24
...NOR gate. 25... End signal generation section, 26... Enable signal generation section. Patent applicant Rico Co., Ltd. Diagram: Super 1 device 3 Registration roller light 5 Pre-charge cage 7 Current 3 koshikuho 1 9 Moxibustion side recovery... Pilgrimage 3... Toner VJ Collection 5... Print song ■ Wholesale 2... Leprosy U next 4... Sensation 4 kilos... Sea γ' Nine nails 8 Roll 5 times - Theft 10 Phisonta spear → Force 2 - Cleaning field 14 Kushit Figure J: 1 u ′oaJ Figure A (b)

Claims (1)

[Claims] A light emitting means, a detection means for detecting the amount of light emitted from the light emitting means, a control means for controlling the amount of light emitted from the light emitting means to a constant value according to an output of the detection means, and control information from the previous control is stored in advance. A light amount control device, comprising: a non-volatile storage means for setting a control start value of the control means immediately after power is turned on based on information stored in the non-volatile storage means.