JPS58198020A - Device for diagnosing optical system of laser scanning - Google Patents

Abstract

PURPOSE:To detect easily a fault or to execute repair easily, by detecting scanning position, the abnormality of revolution and the reduction of an output, on the basis of the output from a photosensor arranged in a scanning range, and displaying the detected reslut. CONSTITUTION:The photosensor 19 is arranged on the scanning starting position of laser light. When the scanning range of the laser light is shifted in the scanning direction, the output of the sensor 19 does not coincide with the setting time for rase time, so that the rise time of an output pulse from a comparator 22 is changed. A position detecting part 24 detects the change of the rase time and a lamp 31 is turned on by the detected output. If an abnormality such as uneven revolution is generated in a turning polyhedral mirror, the output of the sensor 19 is compared with reference voltage E1 by the comparator 22, the interval between output pulses is made different from a set value, and the result is detected by a revolution detecting part 25, and a lamp 32 is turned on by the detected output.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser scanning optical system of a facsimile or a laser printer, and more particularly to a diagnostic device for a laser scanning optical system that detects and warns of abnormalities or failures occurring in the optical system.

Conventional diagnostic devices for laser scanning optical systems (hereinafter referred to as "diagnostic devices") detect abnormalities in the laser scanning optical system using a predetermined scanning position detector. There is a disadvantage in that it is not possible to know its rotational state because it does not have a function to detect it.

Furthermore, even when the rotation of the motor that drives the rotating polygon mirror is controlled, the rotation state is not configured to be externally monitored, and the control device is separate from the scanning position detector. The system was installed independently, and there was a lot of waste and insufficiency in terms of device implementation and functionality.

This invention has been made in view of the above-mentioned circumstances, and it improves the drawbacks of the above-mentioned prior art, and uses a simple device to diagnose the scanning position, laser output, and rotational state of the rotating polygon mirror, thereby facilitating repair work. The purpose is to provide a diagnostic device that can

That is, in this invention, a scanning position, laser output, and rotation abnormality are detected by a detection device based on the output of a sensor placed at a predetermined position within the scanning range of the rake light, and the type of abnormality is determined based on the detection result. This system makes it easy to discover abnormalities and perform repair work by displaying appropriate displays.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A diagnostic apparatus for a laser scanning optical system according to the present invention will be described in detail below according to embodiments shown in the accompanying drawings.

FIG. 1 shows a schematic configuration of a laser printer equipped with a diagnostic device according to the present invention.

In this figure, light emitted from a laser light source 11 is modulated by image information by a modulator 12, and then passes through a slit 13 and a lens system 14. It reaches the top of the drum 18. At this time,
A rotary polygon mirror 15 driven by a driving means 16 causes light to scan over the photosensitive drum 18 in the range indicated by an arrow F1 in the figure. Since the photosensitive drum 18 is rotated in a predetermined manner by a driving means (not shown), image information is recorded on the photosensitive drum 18 as a latent image. Further, the outer periphery of the photosensitive drum 18 is provided with devices (not shown) for visual imaging, transfer, fixing, cleaning, charging, etc., so that printing can be performed on a predetermined sheet of paper.

Further, within the scanning range indicated by the arrow F1 mentioned above, a photosensor 9 consisting of a light receiving element is provided at the scanning start position, and is connected to a detection device 20, which will be described in more detail.

The detection device 20 has a circuit configuration as shown in FIG.
It has a function of detecting an abnormality in the laser output or the rotational state of the rotating polygon mirror 15, and lighting up the lamps 31 to 33 of the display device 30 provided at an appropriate position on the laser printer main body.

Next, in FIG. 2, the output of the photosensor 19 is amplified by an amplifier 21 and then input to comparison circuits 22 and 23. Of these, the comparison circuit 22
1, the reference voltage E1 is input, and the input of the photosensor 9 is from this IE1.
It has a function of outputting a constant pulse when the current is reached. The level of this reference voltage E1 is, for example, 1! The reference voltage F2 is similarly input to the comparator circuit 23, and the input of the photosensor 19 is set to 11 of (A) in FIGS. 3(A) and 3(B). It has a function of outputting a constant pulse when the voltage exceeds E2.The level of this reference voltage E2 is, for example, [-2] in (A) of FIG. 3(C).

Next, the output of the comparison circuit 22 is transmitted to a position detection section 24,
The signals are connected to the rotation detection section 25 so as to be inputted thereto. Of these, the position detection section 24 has a function of detecting a shift in the scanning position of the laser beam from the input, and the rotation detection section 25 has the function of detecting an abnormality in the rotational state of the rotating polygon mirror from the input. have. Further, the output of the position detection unit 24 is input to the lamp 31 and the lens system 14
．． 1 (not shown in FIG. 1) is input to an adjustment section such as 17 that performs position adjustment. Rotation detection section 25
Similarly, the output thereof is input to the lamp 32 and also to the drive 41 of the rotary polygon mirror 15 and the adjustment section 2 for controlling the drive of the means 16.

On the other hand, the output of the comparison circuit 23 is connected to be input to the output detection section 26. This output detection section 26 has a function of detecting the intensity of the laser light from the input, that is, the state of the output.The output is input to the lamp 33 and controls the rape light source 11 or the modulator 12. 3 is input to the adjustment section that adjusts the output.

Next, the overall operation of the above embodiment will be explained with reference to FIGS. 1 and 2.
The explanation will be made with reference to the time charts of FIGS. 3(A) to 3(C) in addition to the drawings. In FIGS. 3A to 3C, (A) shows the position detection operation, (B) shows the rotation detection operation, and (C) shows the output detection operation.

First, detection of the scanning position of the laser beam will be explained. As described above, the photosensor 19 is placed at the laser beam scanning start position. Accordingly, when the scanning range of the laser beam is shifted in the scanning direction, the output of the photosensitive sensor 19 becomes as shown in (a) of FIG. 3(A). In other words, the time when the output of the photosensor 19 rises does not coincide with the preset time and deviates back or forth. Specifically, as shown in FIG. 3(A) (b), the comparison circuit 2
The rise times of the second output pulses are different.

This is detected by the position detection unit 24 and shown in (A) of the same figure.
The output shown in (c) is performed, and the lamp 31 lights up as shown in (d) of (A) in the same figure.This allows the operator to easily and quickly monitor that any abnormality has occurred in the scanning position. On the other hand, the output of the position detection section 24 is also input to the adjustment section 1, which allows the lens system 14 to be
．． 17, etc., and the scanning position is adjusted to an appropriate position.

Next, detection of the rotational state of the rotating polygon mirror 15 will be described. If an abnormality such as uneven rotation occurs in the rotating polygon mirror 15, the photosensor 19 will output an output as shown in (a) of FIG. 3(B). Furthermore, this output is input to the comparator circuit 22 and compared with the reference voltage E1, and the pulse shown in (b) of FIG. 3(B) is output, similar to (b) of FIG. 3(A). . If there is no abnormality as described above, pulses are output from the comparator circuit 22 at the preset scanning time interval, but if an abnormality occurs in the rotating polygon mirror 15, the time interval of the pulses is output from the preset value. Become different. This is detected by the rotation detection section 25, and the output shown in (c) of FIG. 3(B) is performed, and furthermore, the lamp 32 is turned on as shown in (d) of FIG. 3(B). This allows the operator to monitor whether an abnormality has occurred in the rotating polygon mirror 15. On the other hand, the output of the rotation detection section 25 is also input to the adjustment section 2, and appropriate drive adjustment is made to the drive means 16 so that the rotation operation of the rotating polygon mirror 15 is properly performed. Become.

Next, detection of laser light output will be explained.

As described above, the comparator circuit 23 has the function of outputting a pulse when its input becomes higher than the reference voltage F2, and the level L2 of the reference voltage E2 is higher than the photosensitive drum 1.
The laser light level is set at the level required for 7- to form a latent image on 8. Therefore, as shown in (a) of Figure 3(C), the rate! If the light output decreases more than necessary, the comparator circuit 23 will not output any pulses, as shown in (b) of FIG. 3(C). This is detected by the output detection section 26,
The output shown in (c) of Figure 3(C) is performed, and
The lamp 33 lights up as shown in (d) of C). This allows the operator to monitor whether an abnormality has occurred in the laser output. On the other hand, the output of the output detection section 26 is
3 is also input to the adjustment section, and appropriate adjustments are made to the laser light source 11 or the modulator 12, so that, for example, modulation efficiency is adjusted so that the laser output becomes an appropriate value.

In the above embodiment, if it is necessary to perform a particularly high-speed detection operation, the purpose can be achieved by using a P-1-N type photodiode as the photosensor 19. Further, although a comparator is used as the comparison circuit 23, it may be configured with an A/D converter to digitize the input and detect the output using the digital signal. In addition, in the above embodiment, the adjustment section has 1 to 3
The system is configured to detect an abnormality and adjust the laser scanning optical system to eliminate the abnormality.However, if you simply want to know whether or not an abnormality has occurred, it is not necessary to have one or more parts in the adjustment section.
There is no need to set fK3.Furthermore, although the photosensor is set at the scanning start position, it may be placed at another position if there is no problem in forming a latent image and the above detection operation can be performed satisfactorily. You can.

As explained above, according to the diagnostic device for a laser scanning optical system according to the present invention, scanning position detection, rotation abnormality detection and output are performed based on the output of the photosensor placed at a predetermined position within the scanning range of the laser beam. We decided to simultaneously detect the drop and display a predetermined display if an abnormality is found, so it is possible to quickly understand the occurrence of an abnormality in the laser scanning optical system, and also display the type of abnormality. Therefore, an excellent effect is achieved in that abnormality can be accurately diagnosed and subsequent repair work can be performed easily.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the general configuration of a laser printer equipped with a diagnostic device according to the present invention, FIG. 2 is a block diagram showing an example of the configuration of the diagnostic device, and FIGS. 3 (A) to (C) are Time charts 1 to 1 show the operation of the diagnostic device. 19...No A+~Sen 1S, 24...Position detection section, 25...Rotation detection section, 26...Output detection section, 31
...first display section, 32...second display section, 33.
...Third display section. Figure 3 (A) (8
)99- (C)

Claims (1)

[Claims] A photosensor placed at a predetermined position within the scanning range of the laser beam, a position detection section that detects an abnormality in the scanning position from the rise of the output of this photosensor, and an indication of the presence or absence of an abnormality based on the output of this position detection section. a first display section, a rotation detection section that detects rotation abnormality based on the time interval of the output of the photo sensor, a second display section that displays the presence or absence of an abnormality based on the output of the rotation detection section, It is characterized by comprising an output detection section that detects a decrease in the output of the laser beam from the magnitude of the output of the sensor, and a third display section that displays the presence or absence of the output decrease based on the output of the output detection section. Diagnostic device for laser scanning optical system.