JPS61276472A - Optical detector - Google Patents

Abstract

PURPOSE:To simplify adjusting work by change or inspection etc. of apparatus by making detection of optical signals exact by driving a photodetector in specified direction. CONSTITUTION:A plate 1 is provided to shade about a half face of fiber of incident side of a light beam, and stable detection of sharp rising up is obtained by a scanning beam 30 that passes through a sharp edge of the plate 1. A shifting device 2 consisting of rack and pinion moves the detector 7 in vertical direction in order to make a fixed luminous flux enter the photodetector 7, and the driving force is obtained from a servomotor 4. The scanned light beam 30 enters a beam detectors 5a, 5b consisting of the photodetector 7 and a photodiode. Driving of the motor 4 is controlled based on detection output of the device 5a, 5b.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention detects a light beam scanning a photoconductor in a light beam scanning device in a recording device such as a laser beam printer that records an image using a light beam. This invention relates to a photodetection device.

[Conventional technology]

FIG. 4 is a perspective view of a scanning optical device of a conventional laser beam printer. - In this figure, the light beam emitted from the semiconductor laser 21 is focused into a parallel light beam by the collimator lens 22, and is reflected and scanned by the surface of the polygon mirror 23, which is rotating in the direction of the arrow 28 at a constant rotation speed. After the light flux scanned at a constant angular velocity passes through the fθ lens 24, the scanning beam 3o is focused onto the surface of the photosensitive drum 25, and is shown by the arrow 29.
The scanning direction is scanned at a constant linear velocity onto the surface of the photosensitive drum 25 to form a scanning line 31 on the surface of the photosensitive drum 25.

The beam detection device for detecting the scanning beam 30 consists of a reflection mirror 26 provided at a specific position on the optical path of the scanning beam 3o and a photodetector 27 for receiving the reflected beam. reflected at 26, f
The light is received by a photodetector 27 placed approximately at the focal point of the θ lens 24.

The photodetector 27 functions to determine the time point at which the recording signal starts, and a control circuit (not shown) generates a signal for starting the recording signal after a certain period of time from the time of light reception. In response to this signal, the semiconductor laser 21 emits a laser beam that is brightly and darkly modulated according to the recording signal by a modulation circuit (not shown), and a latent image of a recording image is formed on the photosensitive drum 25 rotating in the direction of the arrow 32.

As described above, the scanning optical device of the conventional laser beam printer includes a laser device as a light source and an fθ lens 2 that focuses light onto the generatrix of the surface of the polygon mirror photosensitive drum 25 that scans the laser device.
4, and a beam detection device 27 for detecting a specific position of the scanning beam.

[Problem that the invention seeks to solve]

However, in conventional scanning devices, it is necessary to detect a light beam scanning at high speed with a high response speed, so a photodetector such as a Pinfont diode is used, but the size of the photodetector is It is necessary to adjust the position of the reflecting mirror 26 or the photodetector 27 in order for the beam to enter the light-receiving element correctly, which is as small as 0.5 layer angle. is connected to the main body and the position adjustment work must be performed while observing the output waveform of the photodetector 27, which necessitates carrying the measuring equipment for maintenance purposes, which significantly reduces work efficiency. was there.

Furthermore, if the beam position shifts due to replacement of the polygon mirror 23 or semiconductor laser 21, the photodetector 27 may become unable to receive light due to the slight position shift, and the above-mentioned adjustment work must be performed. It disappears. This method of connecting the measuring device to the main body each time adjustments are made through replacement results in a significant decrease in maintenance, and improvements are desperately needed in this regard as well.

The present invention was made to solve the above problems, and uses a simple mechanism to drive the photodetection means in a predetermined direction and quickly position it so that the optical signal can be detected accurately.
The object of the present invention is to obtain a photodetecting device that can greatly simplify adjustment work such as replacing or inspecting equipment.

[Means for solving problems]

The photodetector according to the present invention includes a moving mechanism for moving a photodetector in a predetermined direction, a beam detecting means for detecting a light beam incident on the photodetecting means, and a moving mechanism for moving the photodetector in accordance with the output of the beam detecting means. It is provided with a driving means for driving.

[Effect]

In this invention, the driving means moves the photodetector within a predetermined range according to the light beam incident position detected by the detection means, and stops the photodetector at the position where the light beam is detected.

〔Example〕

FIG. 1 is a perspective view of a photodetector according to an embodiment of the present invention. Reference numeral 1 denotes a light shielding plate, which is attached so as to shield the opposite side of the fiber on the scanning start side, that is, the light beam incidence side. By passing the scanning beam 30 through the sharp edge of the light shielding plate 1, a stable detection signal with a sharp rise can be obtained. Reference numeral 2 denotes a mover stage composed of, for example, a rack and pinion, which adjusts its movement in the vertical direction shown by the arrow 3 so that a constant beam of light is incident on the photodetector 7. Reference numeral 4 denotes a driving means; For example, it is composed of a servo motor. 5a and 5b are beam detection means, for example, composed of a photodiode. 6 is a reflecting mirror that guides the scanned light beam 3o to a photodetector 7.

FIG. 2 is a control block diagram of a photodetecting device showing one embodiment of the present invention, and 11 is a sequence controller (CP
U) controls the entire device.

12 is an I10 port, and 13 is an input interface, into which the light beam detection signal output from the photodetector 7 and the detection signals from the beam detection means 5a and 5b are input. 1
A drive circuit 4 drives the drive means 4. 15 is an encoder that outputs a predetermined pulse signal in accordance with the rotation of the driving means 4;

A position counter 16 counts pulse signals output from the encoder 15 and outputs a position signal indicating the position of the photodetector 27. A display section 17 displays whether or not the light beam is adjusted based on the detection signals from the beam detection means 5a and 5b and the light beam detection signal from the photodetector 7. A memory 18 stores the operational state of the sequence controller 11 and the input/output relationship of the I10 boat 12.

Next, the positioning control operation of the present invention will be explained with reference to FIG.

FIG. 3 is a flowchart illustrating the positioning control operation of the present invention. Note that (1) to (13) indicate each step.

The CPU 11 initializes the repetition count value M set in the memory 18, that is, sets it to rOj (1). Then,
CP determines whether the photodetector 7 is detecting a laser beam, that is, whether it is detecting a beam detection signal.
If U11 is determined 2), and YES, step (11)
If NO, proceed to the beam detection means 5a, 5b.
The CPU 11 determines whether or not the laser beam is detected (3). If this judgment is No, proceed to step (13), display r error 1 on the display section 17,
If YES, the drive circuit 14 sends a signal for normal rotation to the drive means 4 (4). By driving the drive means 4, the photodetector 7 moves in a predetermined direction, for example, in the direction of the position where the beam detection means 5a is arranged. Next, in accordance with this movement, the CPU 11 determines whether the photodetector 7 has detected the laser beam (5). In this judgment, NO
In this case, the CPU 11 determines whether the position counter 16 has finished counting the pulse signals output from the drive means 4 by a preset number (8). If No, the CPU 11 waits for the end of the count, and if the answer is YES, the CPU 11 repeats the process. FlJ is added to the number of times M (7). Next, the CPU 11 determines whether or not the number of repetitions M has reached a preset value n (set in the memory 18), and if No, then
The drive circuit 14 sends out a drive signal to reverse the drive means 4, and the photodetector 7, for example, the beam detection means 5b.
, and return to step (5) (9).

On the other hand, if the determination in step (5) is YES, the drive circuit 14 sends a signal to stop the drive means 4 (
10). After this, the CPU 11 determines whether a beam detection signal is output from the photodetector 711), and Y
If the answer is ES, the display section 17 displays "incidence" of the laser beam and the control ends (12); if No, step (13)
).

Also, if YES in step (2), step (
Proceeding to step 12), "1 incidence of laser beam" is displayed on the display section 17, and the control is ended.

Thereby, when the laser beam is incident within the movable range of the photodetector 7, the photodetector 7 is driven and stopped at an optimal position.

〔Effect of the invention〕

As explained above, the present invention includes a moving mechanism for moving a photodetector in a predetermined direction, a beam detecting means for detecting a light beam incident on the light detecting means, and a moving mechanism for moving a photodetector in accordance with the output of the beam detecting means. Since a driving means is provided, a simple mechanism can be used to drive the light detection means in a predetermined direction and position it quickly so that optical signals can be detected accurately, greatly reducing adjustment work such as replacing or inspecting equipment. It has the advantage of being simple.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a photodetecting device showing an embodiment of the present invention, FIG. 2 is a control block diagram of the photodetecting device showing an embodiment of the present invention, and FIG. 3 shows the positioning control operation of the present invention. FIG. 4 is a perspective view of a scanning optical device of a conventional laser beam printer. In the figure, 1 is a light shielding plate, 2 is a moving means, 4 is a driving means, and 5a
, 5b is a beam detection means, 7.27 is a photodetector, 11 is a CPU, 12 is an I10 board, 13 is an input interface, 14 is a drive circuit, 15 is an encoder, 16 is a position counter, 17 is a display unit, 18 is a It's memory. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] a scanning means for scanning a light beam on a scanned medium by modulating a light source according to an image signal; an imaging means for forming an image of the light beam scanned from the scanning means on the scanned medium; An optical scanning device comprising a light detection means for detecting a specific position, a moving mechanism for moving the light detector in a predetermined direction, a beam detection means for detecting the light beam incident on the light detection means, and the beam A photodetection device comprising: a drive means for driving the moving mechanism according to an output of the detection means.