JPH0560988A - Light beam detector - Google Patents

Abstract

PURPOSE:To provide a light beam detector which improves the workability of adjustment by referring to an output waveform to adjust the position of a photodetector and eliminating a need of a jig for adjustment. CONSTITUTION:In the light beam detector which is arranged on the scanning line of a light beam and detects the light beam to generate a synchronizing signal, a photodetector 20 having a light reception face 20a of prescribed size is used, and the photodetector 20 is so arranged that the scanning direction of the light beam to the light reception face 20a of the photodetector 20 coincides with the direction where a maximum output is obtained from the photodetector 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light beam detecting device which can be used, for example, in a synchronizing signal detecting optical system in an optical scanning device.

[0002]

2. Description of the Related Art In, for example, an optical scanning device, a light receiving element detects a scanning start position of a laser beam, a synchronizing signal is generated after a predetermined time has elapsed from a detection signal output point by the light receiving element, and the synchronizing signal is synchronized with this synchronizing signal. Driving of the laser light source is started by the recorded information signal. The laser beam is modulated according to the recorded information signal, and the driving start position of the laser light source is synchronized as described above, so that a good latent image without jitter is formed on the photosensitive surface of the photoconductor. To be done.

FIG. 13 shows an example of a light beam detecting device used in a conventional optical scanning device or the like, which is designated by reference numeral 40.
Indicates a scanning line by the light beam, and this scanning line 40
Scans in a direction parallel to one side of the light receiving surface 50a on the rectangular light receiving surface 50a of the light receiving element 50. FIG. 14 shows the detection output of the light beam by the light receiving element 50, and the detection output a of a size (time width) corresponding to the size of the light receiving surface 50a in the scanning line 40 direction is obtained.

[0004]

In the light beam detecting device used in the light scanning device or the like, the initial position of the light receiving element 50 is adjusted so that the scanning line of the light beam passes through the center of the light receiving surface 50a. If the scanning line of the light beam is the light receiving surface 50a.
If the initial setting is off the center of
This is because when the position of the light receiving element 50 is displaced due to vibration or the like, the scanning line of the light beam deviates from the light receiving surface 50a, and a detection output cannot be obtained. Therefore, conventionally, the position of the light receiving element 50 is adjusted by using a jig, and the scanning line of the light beam is set to the light receiving surface 50.
It was set to pass through the center of a. Therefore, there is a problem that a jig for adjustment is required and that the adjustment using the jig is not a good operation.

The present invention has been made to solve the above-mentioned problems of the prior art. The position of the light receiving element can be adjusted while observing the output waveform, and a jig for adjustment is not required. It is an object of the present invention to provide a light beam detection device capable of improving the workability of adjustment.

[0006]

According to the present invention, a light receiving element having a light receiving surface of a predetermined size is used, and the scanning direction of the light beam with respect to the light receiving surface of the light receiving element is such that the maximum output is obtained from the light receiving element. The light receiving element is arranged so that

[0007]

The position of the light receiving element can be adjusted while checking the width of the output signal of the light receiving element. When the maximum signal width is obtained from the light receiving element, the scanning line of the light beam passes through the center of the light receiving surface, and the signal width becomes smaller as the scanning line of the light beam deviates from the center of the light receiving surface. Therefore, the position of the light receiving element is adjusted so that the maximum signal width is obtained from the light receiving element, and is fixed at that position.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A mirror angle adjusting device according to the present invention will be described below with reference to the drawings. The illustrated embodiment is a light beam detecting device in a synchronizing signal detecting optical system of an optical scanning device. Therefore, first, an example of the optical scanning device and its synchronization signal detection optical system will be briefly described.

In FIGS. 8 and 9, a laser light source 12 made of a semiconductor laser or the like is fixed to one side portion of a chassis 11 having a peripheral wall, and a cylindrical lens 13 is provided in the path of a laser beam emitted from the laser light source 12.
And a polygon mirror 15 that is driven to rotate by a motor 14 is further arranged. By rotating the polygon mirror 15, the laser light source 1
The laser beam from 2 is deflected in a certain angular range. The laser beam deflected by the polygon mirror 15 passes through the fθ lens 16 arranged in the vicinity of the polygon mirror 15, and is reflected by the first scanning reflection mirror 17 arranged at the upper edge of the chassis 11 in FIG. It
As shown in FIG. 9, the first scanning reflection mirror 17 reflects the laser beam in a folded shape at an acute angle.
This reflected light is further reflected toward the outside of the chassis 11 by the second scanning reflection mirror 18 arranged at the inner bottom of the chassis 11.

As shown also in FIG. 10, there is a photoconductor (not shown) or the like on the path of the reflected light by the second scanning reflection mirror 18, and the scanning line 2 is formed on the photoconductive surface of this photoconductor or the like.
Draw one. In FIG. 10, if the scanning direction of the scanning line 21 is from right to left as indicated by the arrow, a part of the reflected beam by the second scanning reflection mirror 18 is reflected to the right side which is the scanning start side. Mirror 19 of is arranged. A light receiving element 20 is arranged on the path of the reflected beam by the mirror 19. As shown in FIG. 8, the light receiving element 20 includes the fθ lens 16 and the second scanning reflection mirror 1.
8 is fixed to the chassis 11 so as not to hinder the progress of the laser beam passing through the fθ lens 16. In order to guide a part of the laser beam to the light receiving element 20, the mirror 19 is attached with a predetermined inclination angle as shown in FIG.

As can be seen from the positional relationship between the mirror 19, the light receiving element 20 and the second scanning reflection mirror 18 described above, the light receiving element 20 detects the scanning start position of the laser beam. Therefore, when a synchronizing signal is generated after a fixed time from the time when the detection signal is output by the light receiving element 20 and the laser light source 12 is started to be driven by the recorded information signal in synchronization with the synchronized signal, the laser beam is generated according to the recorded information signal. Are modulated to form latent images on the photosensitive surface of the photoconductor.

As described above, since the mirror 19 is for guiding the laser beam to the light receiving element 20 for detecting the synchronizing signal, its tilt angle must be adjusted with high accuracy, and the adjustment accuracy is high. If not, the light receiving element 20
The laser beam will not be properly incident on the recording medium, and the recorded information signal will be out of synchronization and an image will not be formed correctly. 3 to 7 show specific examples of the mirror angle adjusting device.

In FIGS. 3 to 7, the mirror 19 is mounted on the surface of the mirror holder 23. The mirror holder 23 has bent portions 24, 24 having surfaces in directions orthogonal to each other on the outer edge portion. These bent portions 24,
Two side surfaces of the mirror 19 which are orthogonal to each other are pressed against the mirror 24, and further, two positioning protrusions 25, 25 fixed or projected on the mirror holder 23 are used to form the mirror 1
By positioning the other two side surfaces of the mirror 9 which are orthogonal to each other, the mirror 19 is positioned at a predetermined position of the mirror holder 23.
Is positioned. Adhesive 2 at multiple points in this state
The mirror 19 is attached to the mirror holder 2 by bonding with 6.
It is attached to 3.

An abutting portion 28 is formed on the mirror holder 23 by bending one side edge thereof. Circular insertion holes 29, 29 are formed in the mirror holder 23 at the edge portion where the abutting portion 28 is formed and on both sides of the abutting portion 28. The contact portion 28 is formed on a straight line connecting the centers of the insertion holes 29, 29. The mirror holder 23 also has an elongated hole 27 formed at a position different from the insertion holes 29, 29. One insertion hole 2 with respect to the straight line connecting the centers of the two insertion holes 29, 29
The insertion holes 29, 29 and the elongated hole 27 are arranged so that the straight line connecting the center of the elongated hole 27 and the center of the elongated hole 27 is orthogonal to each other.

The mirror holder 23 is attached to the base body 30 as follows. The two insertion holes 29, 29
The screws 31 and 31 inserted into the screw hole and the adjusting screw 32 inserted into the elongated hole 27 are respectively screwed into the screw holes of the base body 30. By screwing the two screws 31, 31 into the base body 30, the tip end of the abutting portion 28 of the mirror holder 23 abuts the base body 30 as shown in FIG. 4, and the adjusting screw 32 as shown in FIG. The mirror holder 23 is firmly attached to the base body 30 by being screwed into the base body 30. Between the base body 30 and the mirror holder 23,
A leaf spring 33 is interposed which biases the base body 30 and the mirror holder 23 in a direction in which they are separated from each other.

Now, with the abutting portion 28 abutting on the base body 30, the screws 31, 31 on both sides of the abutting portion 28 are adjusted so that the abutting portion 28 serves as a fulcrum.
3 and the mirror 19 integrated therewith can be tilted in the left-right direction in FIG. 4 to adjust the tilt angle of the mirror 19 in one direction. Since this adjustment is performed by abutting the abutting portion 28 against the base body 30 and using the abutting portion 28 as a fulcrum, the mirror holder 23 is firmly attached to the base body 30 even after the adjustment, and the mirror holder 23 vibrates even if the optical scanning unit vibrates. 23 does not resonate, and the detection output waveform of the light receiving element 20 does not fluctuate.

Further, by adjusting the adjusting screw 32, the mirror holder 23 and the mirror 19 integrated with the mirror holder 23 with the abutting portion 28 as a fulcrum are moved in the left and right direction in FIG. 6, that is, the tilting direction of the mirror 19 by the screws 31 and 31. The tilt angle in the other direction of the mirror 19 can be adjusted by tilting the mirror 19 in a direction orthogonal to the direction. The leaf spring 33 also contributes to the tilt angle adjustment, but since the angle is adjusted with the abutting portion 28 of the mirror holder 23 abutting on the base body 30 as a fulcrum, the mirror holder 23 remains a base body even after the adjustment. It is firmly attached to 30.

After adjusting the inclination in each direction, as shown in FIG. 6, an adhesive 35 is applied between each screw 31, 32 and the base body 30.
It is desirable that the adhesive 36 is applied between the screws 31 and 32 and the mirror holder 23 so that the mirror holder 23 and the base body 30 are more firmly and reliably integrated.

The light beam reflected by the mirror 19 is guided to the light receiving element 20, but the mirror 19 is inclined with respect to the incident direction of the light beam as shown in FIG.
Moreover, on the surface of the mirror 19, the light beam
Are arranged so as to traverse diagonally. On the other hand, the light receiving element 20 includes the mirror 1 so as to directly face the light beam from the mirror 19 and as shown in detail in FIG.
Scanning line 40 on the light receiving element 20 of the light beam from
Are arranged so as to cross the light receiving surface 20a of the light receiving element 20 in a diagonal direction.

As described above, by arranging the light receiving element 20 so that the scanning line 40 of the light beam on the light receiving element 20 crosses the light receiving surface 20a in a diagonal direction, the light beam on the light receiving surface 20a as shown in FIG. The maximum light receiving range is the range l, and the detection output width of the light beam by the light receiving element 20 is maximum. This maximum detection output width is shown in Fig. 2.
(A) If the waveform A is used, the detection output width is gradually reduced as shown by the waveform B in FIG. 2B as the scanning line 40 deviates from the diagonal line of the light receiving surface 20a. Therefore, while measuring or observing the detection output width of the light receiving element 20, the position and posture of the light receiving element 20 are adjusted so as to maximize the detection output width, and fixed at that position.

In the above embodiment, the scanning line 40 of the light beam is slanted, but the light beam is made to run horizontally as in the conventional case, and the light receiving surface 60a having a diamond shape as shown in FIG. 11 is received. The light may be input to the element 60, or may be input to the light receiving element 70 having a circular light receiving surface 70a as shown in FIG.

According to the embodiment described above, the light receiving element 2
Since the light receiving element 20 is arranged so that the scanning direction of the light beam with respect to the light receiving surface 20a of 0 is the direction in which the maximum output is obtained from the light receiving element 20, the detection output of the light receiving element 20 is detected or measured while observing. The position and orientation of the light receiving element 20 may be adjusted so that the output becomes maximum output.
Since it is not necessary to use a jig as in the conventional case, there is an advantage that the workability of adjustment is improved. Further, since it is easy to adjust so that the scanning line 40 of the light beam surely passes through the center of the light receiving element 20, even if the position of the light receiving element 20 or the adjustment of the mirror 19 is deviated due to vibration or the like, the detection output is obtained. The problem of not coming out can be minimized.

[0023]

According to the present invention, since the light receiving element is arranged so that the scanning direction of the light beam with respect to the light receiving surface of the light receiving element is the direction in which the maximum output is obtained from the light receiving element, the detection output of the light receiving element is It is sufficient to adjust the light receiving element so that the detection output becomes the maximum output while looking, and it is not necessary to use a jig as in the conventional case. Therefore, it is possible to provide a light beam detection device with good workability of adjustment.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part of an embodiment of a light beam detection device according to the present invention.

FIG. 2 is a waveform chart showing an example of the detection output of the above embodiment.

FIG. 3 is a front view showing an example of a mirror holding mechanism that can be used in combination with the device of the present invention.

FIG. 4 is a left side view of the same mirror holding mechanism.

FIG. 5 is a rear view of the above mirror holding mechanism.

FIG. 6 is a plan view of the above mirror holding mechanism.

FIG. 7 is a front view of the same mirror holding mechanism.

FIG. 8 is a plan view showing an example of an optical scanning device to which the device of the present invention is applied.

FIG. 9 is a sectional side view of the same.

FIG. 10 is a perspective view showing a positional relationship between a mirror and a light receiving element of the optical scanning device.

FIG. 11 is a front view showing another example of a light receiving element applicable to the present invention.

FIG. 12 is a front view showing still another example of a light receiving element applicable to the present invention.

FIG. 13 is a perspective view showing an example of a conventional light beam detection device.

FIG. 14 is a waveform diagram showing an example of the detection output of the conventional example.

[Explanation of symbols]

 20 light receiving element 20a light receiving surface 40 scanning line

Claims (1)

[Claims] 1. A light beam detection device which is arranged on a scanning line of a light beam and which detects the light beam to generate a synchronization signal, wherein a light receiving element having a light receiving surface of a predetermined size is used, and the light receiving element receives light. A light beam detecting device, wherein the light receiving element is arranged so that the scanning direction of the light beam with respect to the surface is the direction in which the maximum output is obtained from the light receiving element.