JPH08160334A - Scanning optical device - Google Patents

Abstract

PURPOSE: To simplify the operation for adjusting a write-in starting position. CONSTITUTION: The scanning light Li reflected by the rotary polygon mirror 3, through the image formation lens system 4, forms an image on the photoreceptor of a rotary drum, not shown in the figure, outside the optical box 7 fixed to the main body frame 9. The adjustment of the write-in starting position of the photoreceptor is performed by loosening the machine screws 10a and 10b for binding the positioning pin holding members 11a and 11b integrated with the positioning pins 12a and 12b to the optical box 7, and changing the fixing position of the optical box 7 in the Y axis with respect to the main body frame 9 direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning optical device used in an image forming apparatus such as a laser printer or a laser facsimile.

[0002]

2. Description of the Related Art As shown in FIG. 6, a scanning optical apparatus used in an image forming apparatus such as a laser printer or a laser facsimile linearly scans a laser beam generated from a light source unit 101 having a semiconductor laser 101a with a cylindrical lens 102. -Shaped light flux is condensed to form a rotary polygon mirror 103.
Direction along the axis of rotation (hereinafter, "Z-axis direction")
Say. ) Is deflected and scanned in a predetermined direction (hereinafter referred to as “Y-axis direction”), and passes through a focusing lens system 104 including a spherical lens 104a and a toric lens 104b and a folding mirror 105 to a rotary drum D (see FIG. 7). ) Form an image on the photoconductor above. The light flux imaged on the photoconductor forms an electrostatic latent image by main scanning in the Y-axis direction by rotation of the rotary polygon mirror 103 and sub-scanning in the Z-axis direction by rotation of the rotary drum D.

The scanning light L ₀ of the rotary polygon mirror 103 is separated below the scanning surface by the BD mirror 106a at one end of the scanning surface (XY plane) in the Y-axis direction and is introduced into the BD sensor 106b to start scanning. It is converted into a signal and transmitted to the semiconductor laser 101a of the light source unit 101. The semiconductor laser 101a receives the scan start signal and then starts the write modulation.

The light source unit 101, the cylindrical lens 102, the rotary polygon mirror 103, the imaging lens system 104, the folding mirror 105, the BD mirror 106a and the BD sensor 106b are attached to the side wall or the bottom wall of the optical box 107. The rotary drum D is disposed below the optical box 107, and a window for taking out the scanning light L ₀ reflected by the folding mirror 105 from the optical box 107 toward the rotary drum D is provided on the bottom wall of the optical box 107. 108 is provided. The upper opening of the optical box 107 is closed by a lid (not shown).

The rotary drum D and the optical box 107 are individually assembled to the main body frame 109 of the image forming apparatus. At this time, it is necessary to strictly manage the relative position between the rotary drum D and the optical box 107 so that defocusing does not occur in the point image of the photosensitive drum of the rotary drum D. That is, when the optical box 107 is attached to the main body frame 109, the length of the optical path of the scanning light L ₀ from the imaging lens system 104 in the optical box 107 to the photoconductor of the rotating drum D via the folding mirror 105 is determined. It is required to position the optical box 107 with high accuracy so as to be equal to the focal length of the imaging lens system 104.

Therefore, a pair of positioning pins 111 projecting downward from the bottom surface of the optical box 107 are respectively engaged with a pair of holes (not shown) of the main body frame 109 so as to align them. There is.

Further, in order to deal with defocus due to dimensional changes and positional shifts of each component due to assembly errors due to variations in dimensional accuracy during manufacturing of each component or environmental changes, an optical box for the main body frame 109 is provided. It is desirable that the mounting position of 107 be finely adjusted in the X-axis direction. Therefore, both positioning pins 111 are held by a pair of positioning pin holders 112 that are detachable from the optical box 107, and each positioning pin holder 112 is attached to the optical box 107 by a small amount in the X-axis direction. By moving the optical box 107 and each positioning pin 111
Is devised so that the relative position of the optical box 107 can be finely adjusted by changing the relative position of the optical box 107.

Further, the writing start position of the rotary drum D with respect to the photosensitive member also changes remarkably due to dimensional changes and misalignment of each part due to assembly errors due to variations in dimensional accuracy during manufacturing of each part or environmental changes. Therefore, the rotary drum D and the optical box 107 are attached to the main body frame 10
9, the BD mirror 106a is rotated around the Z axis to change its reflection angle, and the timing of the scanning start signal is adjusted.

In order to adjust the reflection angle of the BD mirror 106a in this manner, the BD mirror 106a must be adjusted.
Since a large number of parts must be used for assembling a, and in addition, since the BD mirror 106a is generally a very small mirror, the parts used for its assembling require high-precision finishing, and therefore High manufacturing cost,
In addition, fine manual work is required for assembling the BD mirror 106a and adjusting the reflection angle.

On the other hand, recently, in order to further reduce the cost of the scanning optical device, it is desired not only to automate the assembling process but also to consistently automate the process of adjusting the position of the parts after assembling.

[0011]

However, according to the above-mentioned conventional technique, as described above, since the scanning start signal detection system for detecting the scanning start signal requires many expensive parts, the scanning optical system is required. It is inevitable that the cost of parts of the apparatus becomes high, and the manual process of assembling the BD mirror and the like is required, which becomes a major obstacle in automating the manufacturing process of the scanning optical device.

The present invention has been made in view of the above problems of the prior art, and the work for adjusting the writing start position of the photosensitive member is simple and easy to automate.
It is an object of the present invention to provide a scanning optical device that does not require a BD mirror or the like and has a low component cost.

[0013]

In order to achieve the above object, a scanning optical device of the present invention comprises a rotary polygon mirror and an optical system for forming an image of scanning light scanned by the polygonal mirror on a photoconductor. A housing for supporting the optical system and the rotary polygon mirror, and a fixing means for fixing the housing to a support, and the fixing means changes the fixing position of the housing at least in the scanning direction. Characterized by being free.

It is preferable that the fixing means can change the fixing position of the housing in at least both the scanning direction of the scanning light and the optical axis direction.

The fixing means is a first positioning member which is freely displaceable with respect to the housing within the scanning plane of the scanning light and is rotatable with respect to the support, and the scanning with respect to the support. It is desirable to provide a second positioning member that is displaceable in the light scanning direction and displaceable with respect to the housing in the optical axis direction of the scanning light.

Further, the first and second positioning means in which the fixing means are respectively displaceable with respect to the housing in the optical axis direction of the scanning light and displaceable with respect to the support in the scanning direction of the scanning light. A member and a third positioning member that is displaceable in the scanning direction with respect to the housing and displaceable in the optical axis direction with respect to the support may be provided.

[0017]

The writing start position of the photoconductor is adjusted by changing the fixed position of the housing with respect to the support in the scanning direction of the scanning light.

Therefore, the work for adjusting the write start position is simple and easy to automate, and no BD mirror or the like is required, so that the cost of parts can be greatly reduced.

If the fixing means can change the fixing position of the housing at least in both the scanning direction of the scanning light and the optical axis direction, the work for adjusting the writing start position as described above,
Since the work of changing the fixed position of the housing in the optical axis direction of the scanning light to eliminate the defocus can be performed in combination, automation of the manufacturing process can be greatly promoted.

The fixing means is a first positioning member which is freely displaceable with respect to the housing within a scanning plane of scanning light and is rotatable with respect to the support, and the scanning with respect to the support. If a second positioning member that is displaceable in the light scanning direction and displaceable with respect to the housing in the optical axis direction of the scanning light is provided, the first positioning member is provided with respect to the housing. The writing start position can be adjusted by displacing the second positioning member with respect to the support in the scanning direction while displacing it in the scanning direction. Further, the imaging position of the scanning light is adjusted by displacing the first and second positioning members with respect to the housing in the optical axis direction,
Defocus can be eliminated. Therefore, there is an advantage that the number of parts required is small and the adjustment work is simple.

Further, the first and second positioning means in which the fixing means are respectively displaceable with respect to the housing in the optical axis direction of the scanning light and displaceable with respect to the support in the scanning direction of the scanning light. If a member and a third positioning member that is displaceable in the scanning direction with respect to the housing and displaceable in the optical axis direction with respect to the support are provided, the first and second The writing start position can be adjusted by displacing the positioning member in the scanning direction with respect to the support and displacing the third positioning member in the scanning direction with respect to the housing. Further, by displacing the first and second positioning members with respect to the housing in the optical axis direction, respectively, and displacing the third positioning member with respect to the support in the optical axis direction, the scanning light beam is formed. You can adjust the image position to eliminate defocus.

This is because the case is positioned at three points with respect to the support, and therefore has an advantage that the case can be assembled in an extremely stable manner.

[0023]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view showing a scanning optical device according to an embodiment, in which a laser beam generated from a light source unit 1 having a semiconductor laser 1a is condensed by a cylindrical lens 2 into a linear light beam. However, a predetermined scanning direction (hereinafter referred to as “Y-axis direction”) perpendicular to a direction along the rotation axis (hereinafter referred to as “Z-axis direction”) by the rotary polygon mirror 3.
Say. ), And an image is formed on a photoconductor on a rotating drum (not shown) through an image forming lens system 4 which is an optical system including a cylindrical lens 4a and a toric lens 4b and a folding mirror 5. The light flux that forms an image on the photoconductor
An electrostatic latent image is formed by main scanning in the Y-axis direction by rotation of the rotary polygon mirror 3 and sub-scanning in the Z-axis direction by rotation of the rotating drum.

The scanning light L ₁ of the rotary polygonal mirror 3 that reaches one end of the scanning surface (XY plane) in the Y-axis direction is introduced into the BD sensor 6, is converted into a scanning start signal, and is converted into a scanning start signal of the light source unit 1. It is transmitted to the semiconductor laser 1a. Semiconductor laser 1
A receives the scan start signal and then starts write modulation.

The light source unit 1, the cylindrical lens 2, the rotary polygonal mirror 3, the imaging lens system 4, the folding mirror 5 and the BD sensor 6 are attached to the side wall or the bottom wall of the optical box 7 which is the housing. The rotary drum is disposed below the optical box 7, and a window 8 for taking out the scanning light L ₁ reflected by the folding mirror 5 from the optical box 7 toward the rotary drum is provided on the bottom wall of the optical box 7. It is provided. The upper opening of the optical box 7 is closed by a lid (not shown).

The optical box 7 is mounted on the body frame 9 of the scanning optical device which is a support. The pair of projecting portions 7a and 7b projecting on both sides of the optical box 7 in the Y-axis direction have screws 10a,
The first and second positioning pin holding members 11a and 11b, which are fixing means, are detachably supported by 10b, and the first and second positioning pin holding members 11a and 11b.
Are positioning members that project downward, respectively.
It is integral with the second positioning pins 12a, 12b.

As shown in FIG. 2, the body frame 9 has a round hole 13a having an inner diameter substantially equal to the outer diameter of the first positioning pin 12a, and a width substantially equal to the outer diameter of the second positioning pin 12b. A long hole 13b in the Y-axis direction having a larger length is provided, and the optical box 7 can be axially aligned with the round hole 13a of the body frame 9 on one of the protruding portions 7a. A circular hole 14a having a large diameter is provided, and the other projecting portion 7b is arranged in the X-axis direction, which is the same as the elongated hole 13b of the body frame 9 and is arranged so as to be orthogonal to the elongated hole 13b. An elongated hole 14b is provided.

The positioning pin holding members 11a and 11b have Y-axis elongated holes 15a and 15b having a width in the X-axis direction which is substantially equal to the outer diameter of the screws 10a and 10b and a length in the Y-axis direction which is larger than the width. Equipped with each screw 10a, 10b
The positioning pin holding member 1 through the elongated holes 15a and 15b.
The positioning pin holding members 11a and 11b are fastened to the optical box 7 by being fastened to the screw holes 16a and 16b of 1a and 11b.
Is integrated with the protruding portions 7a and 7b.

When assembling the optical box 7 to the body frame 9, the first and second positioning pins 1 of the optical box 7 are assembled.
2a and 12b are round holes 13a and elongated holes 13 of the main body frame 9.
The optical box 7 is fixed by engaging with b respectively.

When the screws 10a and 10b are loosened, the first positioning pin 12a penetrates the large-diameter round hole 14a of the optical box 7, so that the first positioning pin 12a is within the range permitted by the dimensions. Hold the holding member 11a with respect to the optical box 7.
The second positioning pin 12b is displaceable in the axial direction and the Y-axis direction, and the second positioning pin 12b is a long hole 14b in the X-axis direction of the optical box 7.
Since it engages with the elongated hole 13b of the body frame 9 in the Y-axis direction, the second positioning pin holding member 11b is attached to the optical box 7 and the body frame 9 respectively within the range permitted by these. It is displaceable in the axial direction and the Y-axis direction. That is, the fixing position of the optical box 7 with respect to the body frame 9 is set to X.
It can be changed in both the axial direction and the Y-axis direction, and the rotation angle in the XY plane can also be adjusted.

The scanning optical device is assembled by assembling the rotary drum to the main body frame 9 by a known method and then fixing the optical box 7 to the main body frame 9 as described above.

When the image forming position of the scanning light L ₁ of the rotary polygon mirror 3 is deviated and defocusing occurs, first, the screws 10a,
After loosening 10b, the fixing position of the optical box 7 with respect to the main body frame 9 is adjusted in the X-axis direction, and if necessary, the rotation angle around the Z-axis is adjusted.

The amount of movement of the optical box 7 in the X-axis direction at this time is equal to the average value of the amount of movement of the positioning pins 12a, 12b with respect to the optical box 7 in the X-axis direction, and the rotation angle of the optical box 7 is , Each positioning pin 12a for the optical box 7,
It is equal to the difference in the amount of movement of 12b in the X-axis direction.

To adjust the writing start position of the photosensitive member, the fixing position of the optical box 7 with respect to the main body frame 9 is adjusted in the Y-axis direction with the screws 10a and 10b being loosened, and the optical box 7 with respect to the rotating drum is adjusted. This is performed by changing the relative position in the Y-axis direction. Optical box 7 at this time
The amount of movement of the first and second positioning pins 12 is
a and 12b are equal to the amount of movement in the Y-axis direction with respect to the optical box 7 and the body frame 9, respectively.

According to this embodiment, since the fixed position of the optical box with respect to the main body frame can be adjusted at least in both the X-axis direction and the Y-axis direction, the defocusing of the scanning light imaged on the rotating drum is eliminated. The writing start position can also be adjusted in the process.

Therefore, unlike the conventional example, the BD mirror and its assembling parts are not required at all, and the number of assembling parts can be greatly reduced, and manual work for adjusting the timing of the scanning start signal is required. Instead, the automation of the assembly process and the like can be greatly promoted, and the cost of the scanning optical device can be greatly reduced.

FIG. 3 is a plan view showing a scanning optical device according to a modification, in which the optical box 7 is provided with a second large-diameter round hole 14a for engaging the first positioning pin 12a. The positioning pin 12 is provided with an elongated hole 24a similar to the elongated hole 14b for engaging the positioning pin 12b.
In place of the round hole 13a of the main body frame 9 for engaging a,
As shown in FIG. 4, an elongated hole 23a similar to the elongated hole 13b is provided, and a third positioning pin holding member 21 is added to the center of the bottom of the optical box 7, and the third positioning pin holding member 21 is It has a third positioning pin 22 which is a positioning member projecting downward from the lower surface thereof, which penetrates an elongated hole 25 in the Y-axis direction provided in the center of the bottom of the optical box 7 and extends along the X-axis of the body frame 9. Engages the slot 23 in the direction. The third positioning pin holding member 21 has a long hole 26 in the Y-axis direction,
It is fastened to the optical box 7 by a screw 27 penetrating this.

With the screws 10a, 10b, 27 loosened, the first and second positioning pins 12a, 12b are movable in the X-axis direction with respect to the optical box 7 and with respect to the body frame 9. The third positioning pin 22 is movable in the Y-axis direction with respect to the optical box 7, and is also movable in the X-axis direction with respect to the main body frame 9. Therefore, similarly to the above, by changing the fixing position of the optical box 7 with respect to the main body frame 9 in the X-axis direction and the Y-axis direction, it is possible to eliminate the defocus and adjust the writing start position, respectively.

In this modification, since the optical box 7 is firmly positioned with respect to the main body frame 9 at three points, there is no possibility that the fixed position of the optical box 7 is displaced during the operation of the scanning optical device. Therefore, it is possible to obtain a scanning optical device having extremely stable performance.

In this embodiment, each positioning pin holding member is fixed to the optical box by screws, but as shown in FIG. 5, the adjustment of the image forming position of the scanning light and the adjustment of the writing start position are completed. After that, each positioning pin holding member 11a, 1a is formed by using a photo-curable adhesive 30 such as an ultraviolet curable adhesive.
The positioning pin holding member 41 similar to 1b and 21 may be fixed to the optical box 37.

[0042]

Since the present invention is configured as described above, it has the following effects.

The work for adjusting the write start position is simple and easy to automate, and no BD mirror or the like is required.

As a result, it is possible to realize a large reduction in component cost and full automation of the manufacturing process.

Further, by combining the work of adjusting the writing start position and the work of adjusting the imaging position of the scanning light to eliminate the defocus, the manufacturing process is further simplified, the manufacturing process is automated and the manufacturing time is reduced. The shortening can be greatly promoted.

As a result, an extremely inexpensive and high-performance scanning optical device can be realized.

[Brief description of drawings]

FIG. 1 is a plan view showing a scanning optical device according to an embodiment.

FIG. 2 is a partially enlarged perspective view showing a part of the device of FIG. 1 in an enlarged manner.

FIG. 3 is a plan view showing a scanning optical device according to a modification.

FIG. 4 is a partially enlarged perspective view showing a part of the device of FIG. 3 in an enlarged manner.

FIG. 5 is a partial cross-sectional view showing a part of a scanning optical device according to another modification.

FIG. 6 is a plan view showing a scanning optical device according to a conventional example.

7 is a cross-sectional view of the scanning optical device in FIG.

[Explanation of symbols]

1 light source unit 3 rotating polygon mirror 4 imaging lens system 5 folding mirror 6 BD sensor 7 optical box 8 window 9 body frame 10a, 10b, 27 screws 11a, 11b, 21, 41 positioning pin holding member 12a, 12b, 22 positioning pin 13a, 14a Round holes 14b, 15a, 15b, 23, 23a, 24a, 2
5,26 Slot 30 Adhesive

Claims (6)

[Claims] 1. A rotary polygonal mirror, an optical system for forming an image of scanning light scanned by the rotary polygonal mirror on a photoconductor, a housing for supporting the optical system and the rotary polygonal mirror, and the housing. There is a fixing means for fixing the body to the support, the fixing means,
A scanning optical device, wherein a fixed position of the housing can be changed at least in the scanning direction. 2. The scanning optical device according to claim 1, wherein the fixing means is capable of changing the fixing position of the housing at least in both the scanning direction of the scanning light and the optical axis direction. 3. A first positioning member, wherein the fixing means is freely displaceable with respect to the housing within a scanning plane of scanning light and rotatable with respect to the support, and the support. 3. A second positioning member that is displaceable in the scanning direction of the scanning light and displaceable in the optical axis direction of the scanning light with respect to the housing. Scanning optics. 4. A first and a second positioning means in which the fixing means is respectively displaceable with respect to the housing in the optical axis direction of the scanning light and displaceable with respect to the support in the scanning direction of the scanning light. 2. A member and a third positioning member that is displaceable in the scanning direction with respect to the housing and displaceable in the optical axis direction with respect to the support. Alternatively, the scanning optical device described in 2. 5. The scanning optical device according to claim 3, wherein the fixing means is configured to screw each positioning member to the housing with screws. 6. The scanning optical device according to claim 3, wherein the fixing unit is configured to fix each positioning member to the housing with a photo-curing adhesive.