JPH07230050A - Writing starting position adjusting mechanism for optical scanner - Google Patents

Abstract

PURPOSE:To finely adjust the detection timing of a light beam by means of a photodetector and to enlarge adjusting width. CONSTITUTION:The photodetector 29 being an area sensor is perpendicularly fixed on the back surface of a supporting board 31. A light shielding board 33 is disposed in direct front of the photodetector 29 on a side where is in a direction opposite to the scanning direction F of the light beam, that is, in a position irradiated with the light beam before the photodetector 29 is irradiated. The light shielding board 33 can be displaced around the screw 34 by loosening the screw 34. The photodetector part 29a of the photodetector 29 has enough width E for adjusting the timing for the light beam to be made incident by the displacement of the light shielding board 33.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device for scanning a light beam in order to write print data on a photosensitive drum in a laser printer or the like, and more specifically, it adjusts a writing start position on the photosensitive drum. Related to the mechanism.

[0002]

2. Description of the Related Art A conventional optical scanning device of this type is shown in FIG. The light information generated by the light source unit 11, that is, the light beam B1 passes through the correction cylinder lens 12 and enters the reflecting surface of the polygon mirror 13 that rotates at a constant speed. With the rotation of the polygon mirror 13, the light beam B1 scans in the direction of arrow A, and the scanning speeds of the fθ lenses 14 and 15 are corrected to constant values.

Before the writing of optical information on the photosensitive drum D is started, the light beam B2 emitted from the fθ lens 15 is reflected by the beam detection mirror 16 and is incident on the light receiving element 18 via the correction cylinder lens 17. Is irradiated. When the amount of light received by the light receiving element 18 exceeds a predetermined value, the beam detection circuit 19 outputs a horizontal synchronizing signal. When the horizontal synchronization signal is input to the control unit (not shown) of the light source unit 11, the light source unit 11 is driven after a predetermined time elapses with reference to this input time point, and the scanning light beam B3 transmits optical information to the photosensitive drum D. Is started to be written.

As described above, the writing start position on the photosensitive drum D depends on the incident timing of the light beam B2 to the light receiving element 18, and the light receiving element 18 is attached to adjust the writing start position. The substrate is moved or the angular position of the beam detection mirror 16 is changed.

[0005]

However, according to such an adjusting method, the position of the light receiving element 18 is easily displaced by tightening the screw for fixing the substrate, and the beam detecting mirror 16 is small, so that fine adjustment is difficult. Is. The present invention is
An object of the present invention is to provide a writing position adjusting mechanism that makes it easy to finely adjust the timing of incidence of a light beam on a light receiving element and further increase the adjustment width of the light receiving element to simplify the work of mounting the light receiving element. I am trying.

[0006]

A writing start position adjusting mechanism according to the present invention includes a light receiving element capable of detecting a light beam at a position upstream of a writing start position of information on a photosensitive member in a light beam scanning direction, The light receiving element is provided immediately before the light receiving element and is provided so as to be displaceable along the scanning direction of the light beam incident on the light receiving element. The area sensor is characterized by having a width sufficient for adjusting the incident timing.

[0007]

The present invention will be described below with reference to illustrated embodiments. FIG. 2 is a plan view showing the configuration of the optical scanning device having the write start position adjusting mechanism according to the first embodiment of the present invention.

A polygon mirror (optical deflector) 22 is provided in the housing 21, and the polygon mirror 22 is provided.
Is driven by a motor (not shown) and rotates counterclockwise in the figure at a constant speed. A light source unit 23 for generating optical information is provided on the front surface of the support plate 31 fixed to the housing 21.
Is provided. The light source 23 and the polygon mirror 2
Between the two, a correction cylinder lens 26 that corrects optical characteristics such as astigmatism due to processing errors of the fθ lenses 24 and 25.
Is provided, and the light information generated by the light source unit 23, that is, the light beam B1, is transmitted to the correction cylinder lens 2
After passing through 6, the light enters the reflecting surface of the polygon mirror 22.

The fθ lenses 24 and 25 are provided on the exit 27 side of the housing 21 with respect to the polygon mirror 22. The rotation of the polygon mirror 22 causes the light beam B1 to perform main scanning in the direction of the arrow A, and the scanning speed is corrected to a constant value by passing through the fθ lenses 24 and 25. Light beam B3 emitted from the fθ lenses 24 and 25
Passes through the ejection port 27 and is irradiated onto the photosensitive drum (photosensitive member) D, whereby a charge signal corresponding to optical information is formed on the photosensitive drum D.

The photosensitive drum D rotates about the major axis, that is, in the sub-scanning direction. The light beam B3 is a laser beam that is on-off modulated and is irradiated onto the photosensitive drum D to form a latent image in a dot sequence. By rotating the photosensitive drum D, these dot arrays form a latent image together with other dot arrays, and this latent image is printed on a predetermined surface by a known method.

A beam detecting mirror 28 is arranged near the portion on the exit 27 side of the fθ lens 25 and corresponding to the start position of writing information on the photosensitive drum D. That is, the beam detection mirror 28 is provided in the plane on which the light beam B3 is mainly scanned.

The reflecting surface 28a of the beam detecting mirror 28 faces the light source section 23 side, and the light beam B4 reflected by the beam detecting mirror 28 can be detected on the back surface of the support plate 31 to which the light source section 23 is attached. The light receiving element 29 is provided. A correction cylinder lens 32 is arranged between the beam detection mirror 28 and the light receiving element 29.
Light beam B4 reflected by the beam detection mirror 28
Moves in parallel to the support plate 31, and the correction cylinder lens 32
And then enters the light receiving element 29. The correction cylinder lens 32 condenses the light beam B4 in the sub-scanning direction perpendicular to the main scanning direction, so that the light beam B4 irradiates the light-receiving element 29 with sufficient energy, and the reflection surface of the polygon mirror 22 has a trouble. The effect of this is compensated.

A beam detecting circuit 51 is connected to the light receiving element 29. The beam detecting circuit 51 sends a horizontal synchronizing signal to the control section 52 of the light source section 23 when the light receiving element 29 receives the light beam B4. Output.

A light shielding plate 33 is provided between the light receiving element 29 and the correction cylinder lens 32, and the light shielding plate 3 is provided.
3 is opposed to a part of the light receiving element 29. FIG. 3 is a view of the light shielding plate 33 and the light receiving element 29 as seen from the direction of arrow C in FIG. Next, the configurations of the light shielding plate 33 and the light receiving element 29 will be described with reference to FIGS.

The light-shielding plate 33 has a light-shielding portion 33a extending parallel to the light-receiving element 29, and a flange 33b which is perpendicular to the light-shielding portion 33a and extends toward the correction cylinder lens 32 side. 21
It is fixed to the bottom of the. The light shielding plate 33 is provided immediately before the light receiving element 29, and by loosening the screw 34,
It can be rotated around the screw 34. Further, the light shielding plate 33 is
It is provided on the upstream side of the light receiving element 29 in the scanning direction F of the light beam B4, that is, at a position where the light beam B4 is irradiated earlier in scanning of the light beam B4 than the light receiving element 29. Therefore, by adjusting the position of the light shielding plate 33, the light beam B4 is changed to the light receiving element 29 as described later.
The timing at which light begins to enter is adjusted.

The light receiving element 29 is an area sensor having a substantially square light receiving portion 29a, and is fixed vertically to the back surface of the support plate 31. The light receiving portion 29a has a width E sufficient to adjust the incident timing of the light beam B4 by the displacement of the light shielding plate 33. That is, if the light receiving element 29 is a line sensor and the width E of the light receiving portion 29a is small,
Depending on the position of the light shielding plate 33, the entire surface of the light receiving portion 29a is shielded, and it is impossible to adjust the incident timing of the light beam B4. However, in the present embodiment, only part of the light receiving portion 29a is shielded and the incident timing. Can be finely adjusted.

The operation of this embodiment will be described. The light beam B1 output from the light source unit 23 is corrected by the correction cylinder lens 26.
Is reflected by the reflecting surface of the polygon mirror 22, and enters the fθ lenses 24 and 25. As the polygon mirror 22 rotates, the light beam B1 is reflected by the beam detection mirror 2
The light is reflected at 8 and enters the light receiving element 29. When the light receiving element 29 detects the light beam B4, the beam detection circuit 5
1 outputs a horizontal synchronization signal, and the control unit 5 of the light source unit 23
Entered in 2. As a result, the light source unit 23 is driven after a lapse of a predetermined time with reference to this input time point, and writing of optical information to the photosensitive drum D is started by the scanning light beam B3.

In order to adjust the writing start position of the optical information on the photosensitive drum D, the timing of incidence of the light beam B4 reflected by the beam detecting mirror 28 on the light receiving element 29 may be adjusted. That is, the screw 34 is loosened, the light shielding plate 33 is rotated around the screw 34, and the light shielding portion 33a
Is adjusted with respect to the light receiving portion 29a. Light beam B
4 scans in the direction of arrow F in FIG. 3, so the timing at which the light beam B4 enters the light receiving unit 29a is adjusted according to the position of the light shielding unit 33a.

As described above, this embodiment is constructed so that the light-shielding plate 33 is displaced to adjust the incident timing of the light beam B4 to the light-receiving element 29. The position of the light shielding plate 33 can be adjusted by loosening and tightening the screw 34, and fine adjustment work is easy. That is, according to the present embodiment, the beam detecting mirror 28 as in the conventional case.
Alternatively, it is not necessary to adjust the position of the light receiving element 29, and the fine adjustment of the writing start position can be easily performed.

Further, according to the present embodiment, since the light receiving element 29 is an area sensor, the adjustment width of the incident timing of the light beam B4 is sufficiently large, and therefore the mounting position of the light receiving element 29 does not need to be determined with high accuracy. Assembling work of the light receiving element 29 is facilitated.

Further, in the present embodiment, the light receiving element 29 and the beam detecting mirror 28 are located upstream of the region R scanned by the light beam B3 for writing optical information on the photosensitive drum D in the scanning direction (see FIG. 2). On the right side of). Therefore, according to the present embodiment, since the optical members such as the light receiving element 29 do not interfere with the light beam B3, the degree of freedom in the arrangement of these optical members is improved and the optical scanning device can be downsized. It's easy.

4 and 5 show a second embodiment of the present invention. In these figures, the members corresponding to those in FIGS. 2 and 3 are designated by the same reference numerals, and only the portions different from the first embodiment will be described below.

Light beam B1 output from the light source unit 23
Passes through the correction cylinder lens 26, enters the reflecting surface of the polygon mirror 22, is reflected there, passes through the correction cylinder lens 32, and enters the light receiving element 29. The light source unit 23 is attached to the housing 21, and the light source unit 2
The light receiving element 29 is provided on the front surface of the support plate 31 connected to the rear end of the light source 3, that is, the surface to which the light source unit 23 is connected. That is, the light receiving element 29 is parallel to the surface of the support plate 31.

A light blocking bolt 41 is screwed into the housing 21 immediately before the light receiving element 29. The leg portion 41a of the light shielding bolt 41 projects from the inner wall surface of the housing 21 in front of the light receiving element 29, and is arranged at a position where the light beam B4 is emitted earlier than the light receiving element 29 in scanning the light beam B4. Has been done. Therefore, by rotating the light blocking bolt 41, the amount of projection of the light blocking bolt 41 from the inner wall surface of the housing 21 changes, and the timing at which the light beam B4 starts to enter the light receiving element 29 is adjusted.

As described above, also in the second embodiment, the incident timing of the light beam B4 to the light receiving element 29 can be finely adjusted only by changing the projection amount of the light shielding bolt 41 with respect to the light receiving element 29, and the photosensitive drum can be adjusted. Fine adjustment of the write start position of D is easily performed, and the same effect as that of the first embodiment can be obtained.

The structure of the light-shielding member such as the light-shielding plate 33 and the light-shielding bolt 41 is not limited to the above-mentioned embodiments, and members having a shape suitable for the purpose can be adopted.

[0027]

As described above, according to the present invention, it is easy to finely adjust the incident timing of the light beam to the light receiving element.
Moreover, since the adjustment width is sufficiently large, the effect of simplifying the work of assembling the light receiving element can be obtained.

[Brief description of drawings]

FIG. 1 is a plan view showing a configuration of a conventional optical scanning device.

FIG. 2 is a plan view showing the configuration of an optical scanning device having a write start position adjusting mechanism according to the first embodiment of the present invention.

FIG. 3 is a view of a light shielding plate and a light receiving element as viewed in the direction of arrow C in FIG.

FIG. 4 is a plan view showing the configuration of an optical scanning device including a write start position adjusting mechanism that is a second embodiment of the present invention.

5 is a view of the light shielding plate and the light receiving element as viewed in the direction of arrow G in FIG.

[Explanation of symbols]

 21 Housing 22 Polygon Mirror (Optical Deflector) 23 Light Source 28 Beam Detecting Mirror 29 Light Receiving Element 29a Light Receiving 31 Supporting Plate 33 Shading Plate 34 Screw 41 Shading Bolt D Photosensitive Drum

Claims (2)

[Claims] 1. An optical scanning device for writing predetermined information on a photosensitive member by deflecting and scanning a light beam emitted from a light source by an optical deflector, wherein the information is written on the photosensitive member. A light receiving element capable of detecting the light beam at an upstream position in the scanning direction with respect to the start position and a light receiving element provided immediately before the light receiving element and displaceable along the scanning direction of the light beam incident on the light receiving element. A light-shielding member, and the light-receiving element is an area sensor having a width that is sufficient for the light-receiving portion to adjust the incident timing of the light beam by the displacement of the light-shielding member. Position adjustment mechanism. 2. The write start position adjusting mechanism for an optical device according to claim 1, wherein the light blocking member is provided at a position upstream of the light receiving element in the scanning direction of the light beam. .