JP3408083B2 - Deflection scanning device - Google Patents

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A deflection scanning apparatus used in an image forming apparatus such as a laser beam printer or a laser facsimile generally has a light source unit 101 in which a semiconductor laser and a collimator lens are unitized as shown in FIG. A cylindrical lens 103 that linearly focuses the parallel laser beam of the parallel light flux on the reflecting surface of the rotating polygon mirror 102;
The rotary polygon mirror 102 and the lens 1 are provided with a lens 104 for forming an image of the scanning light L ₀ deflected and scanned by the rotary polygon mirror 102 on a photoconductor on the surface of the rotary drum D (shown in FIG. 5).
04 is housed in the optical box 110, and the light source unit 1
01 is attached to the side wall 110a of the optical box 110.

The upper opening of the optical box 110 is the optical box 110.
After incorporating all the necessary parts inside, it is closed by a lid member (not shown). The lid member is a flat plate that abuts on the upper end of the side wall 110 a of the optical box 110, and is fixed to the optical box 110 by a known method such as screwing. A window 111 is provided on the bottom wall of the optical box 110 to take out the laser beam deflected and scanned by the rotary polygon mirror 102 toward the external rotary drum D.

The laser light L ₀ generated from the semiconductor laser of the light source unit 101 is collimated by the collimator lens inside the light source unit 101, linearly condensed by the cylindrical lens 103 on the reflecting surface of the rotary polygon mirror 102, and the lens 104 is formed. It is taken out from the window 111 of the optical box 110 toward the rotary drum D through the folding mirror 105. In this way, the scanning light L that forms an image on the photoconductor on the rotating drum D
₀ forms an electrostatic latent image with the main scanning by the rotary polygon mirror 102 and the sub-scanning by the rotation of the rotary drum D.

A motor 1 for driving the rotary polygon mirror 102 to rotate.
Reference numeral 02a includes a rotor integrated with the rotary polygon mirror 102 and a stator mounted on the motor board. The stator is excited by a drive current supplied from a drive circuit on the motor board to rotate the rotor.

The scanning light L ₀ of the rotary polygon mirror 102 is
The BD mirror 1 is provided at the end in the scanning direction (Y-axis direction).
It is reflected to the lower side of the scanning surface (XY plane) by 06a,
It is introduced into the BD sensor 106b. BD sensor 106b
Is output to a controller (not shown). The controller converts the output of the BD sensor 106b into a scan start signal and transmits it to the semiconductor laser of the light source unit 101 to start the write modulation.

[0007]

However, according to the above-mentioned conventional technique, the vibration of the driving part or the like propagates to the light source unit through the optical box during the rotation of the rotary polygon mirror, which causes the light source unit to vibrate. And the emission point of the laser light fluctuates,
There is an unsolved problem that the image quality is deteriorated because the optical axis of the laser beam is shaken and the image forming position on the rotating drum is displaced.

In recent years, in particular, the speed of the deflection scanning device has been increased, and a rotary polygon mirror having a rotational speed of 20,000 rpm has been developed. Even if the rigidity of the entire optical box is enhanced, troubles due to vibration can be avoided. Is difficult. In addition, since the light source unit is attached to the side wall of the optical box, and the upper end of the side wall is a free end, the rigidity is particularly insufficient. For this reason, undulations or the like may occur on the side wall during rotation of the rotary polygon mirror, and as a result, the light source unit may be greatly tilted.

The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and provides a deflection scanning device capable of significantly improving the image quality by reducing the vibration of the light source during the rotation of the rotary polygon mirror. It is provided.

[0010]

In order to achieve the above object, a deflection scanning device of the present invention comprises a light source, a light source supporting means for supporting the light source, and a rotary polygonal surface for deflecting and scanning a light beam generated from the light source. A mirror and an optical box for accommodating the rotary polygonal mirror are provided, and the optical box is provided with a rigidity strengthening means for locally strengthening the rigidity in the vicinity of the light source supporting means. .

The rigidity enhancing means may have a local double wall structure provided on the side wall of the optical box.

The rigidity reinforcing means may have a local rib structure provided on the bottom wall of the optical box.

[0013]

When a light source supporting means such as a light source such as a semiconductor laser or a light source unit in which a collimator lens is unitized is attached to the side wall of the optical box, vibration due to the rotation of the rotary polygon mirror causes the light source supporting means via the optical box. The light emitting point of the light source shifts due to the propagation to the optical axis of the light source, and the optical axis of the light beam is shaken to deteriorate the image quality. Therefore, the side wall of the optical box has a double wall structure or the like near the light source supporting means to locally strengthen the rigidity of the optical box, thereby preventing the vibration of the rotating polygon mirror from propagating to the light source. ..

The side wall of the optical box may locally have a double wall structure, or alternatively, a local rib structure may be provided on the bottom wall of the optical box.

By preventing the light source from vibrating during the rotation of the rotary polygon mirror, the image quality can be greatly improved. by this,
It is possible to realize a deflection scanning device having high performance and suitable for speeding up.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view showing a deflection scanning device according to one embodiment, which is a light source unit 1 which is a light source supporting means in which a laser holder for holding a semiconductor laser as a light source and a collimator lens are unitized. , A cylindrical lens 3 for converging a parallel light beam, which is a light beam generated from the light source unit 1, on a reflecting surface of a rotary polygon mirror 2, and a scanning light L ₁ deflected and scanned by the rotary polygon mirror 2 are illustrated. The rotary polygonal mirror 2, which has a lens 4 and a folding mirror 5 for forming an image on a photosensitive member on a rotating drum,
The cylindrical lens 3, the lens 4, and the folding mirror 5 are housed in the optical box 10. The upper opening of the optical box 10 is shown in FIG.
It is closed by the lid member 6 shown in FIG.

The rotary drum is arranged outside the optical box 10. The scanning light L ₁ is reflected by the folding mirror 5 and is extracted from the window 11 provided on the bottom wall of the optical box 10 toward the rotary drum.

The motor 2a for rotating the rotary polygon mirror 2 is
It has a rotor integrated with the rotary polygon mirror 2 and a stator integrated with the motor substrate 2b, and the stator is excited by a drive current supplied from a drive circuit on the motor substrate 2b to rotate the motor 2a.

Scanning light L ₁ imaged on the photosensitive member of the rotating drum
Forms an electrostatic latent image on the photoconductor in accordance with main scanning by rotation of the rotary polygon mirror 2 and sub-scanning by rotation of the rotary drum.

The optical box 10 has a plurality of supporting members 12 projecting outward from the side wall 10a thereof, and each supporting member 12 is screwed to the main body frame of the deflection scanning device, so that the optical box 10 has a structure. Assemble.

A part of the scanning light L ₁ of the rotary polygon mirror 2 is separated by the BD mirror 6a as a scanning start signal at one end in the scanning direction (Y-axis direction) and introduced into the BD sensor 6b. The semiconductor laser of the light source unit 1 receives the scan start signal transmitted by the BD sensor 6b and starts modulation for image writing.

The light source unit 1 is assembled to the optical box 10 by fixing the lens barrel supporting the semiconductor laser and the collimator lens to the side wall 10a of the optical box 10. As described above, since a semiconductor laser or a collimator lens unitized by a lens barrel is supported only by the rigidity of the side wall 10a of the optical box 10, the vibration of the motor 2a of the rotary polygon mirror 2 propagates to the side wall 10a. Light source unit 1
Is tilted, the optical axis of the laser beam focused on the rotary polygon mirror 2 is swung, and the image quality is deteriorated.

Therefore, the side wall 10a in the vicinity of the portion where the light source unit 1 is assembled in the optical box 10 is provided with a double wall structure which is a means for strengthening the rigidity to locally strengthen the rigidity of this portion. Thereby, the motor 2a of the rotary polygon mirror 2
It is possible to prevent the vibration of (1) from propagating to the light source unit 1 and causing the optical axis of the laser light to swing.

That is, a part of the side wall 10a of the optical box 10 is reinforced by a hollow wall 20 having a double wall structure from the vicinity of the rotary polygon mirror 2 and its motor 2a to the supporting portion of the light source unit 1 to enhance the rigidity. It is intended to prevent the vibration of the motor 2a of the rotary polygon mirror 2 from propagating to the side wall 10a of the portion supporting 1.

The hollow wall 20 includes an outer wall 21 that surrounds the outside of the side wall 10a in a bag shape, and a rib 22 that divides the hollow portion 20a formed between the side wall 10a and the outer wall 21 into a plurality of small spaces.
And is integrally formed with the bottom wall and side wall 10a of the optical box 10.

As described above, the present invention prevents the vibration of the motor of the rotary polygon mirror from propagating to the light source unit through the optical box only by forming a part of the side wall of the optical box into a double wall structure. is there. By avoiding the trouble that the light source unit tilts and the optical axis of the laser beam swings during the rotation of the rotary polygon mirror, it can greatly contribute to the improvement of image quality and the speeding up of printing.

Instead of reinforcing the rigidity of a part of the side wall of the optical box, as shown in FIG.
A portion of b, which is located between the rotary polygon mirror 2 and the light source unit 1, may be locally provided with a rib structure that is a rigidity enhancing means to supplement the rigidity. In this structure, ribs 32 for reinforcement are formed by providing a plurality of irregularities on a part of the bottom wall 10b.

If necessary, the hollow wall 2 shown in FIG.
The rigidity of the side wall 10a of the optical box 10 may be enhanced by 0, and a part of the bottom wall 10b may have a rib structure as shown in FIG.

[0030]

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

Vibration of the light source during the rotation of the rotary polygon mirror can be reduced, and the image quality can be greatly improved. As a result, it is possible to realize a deflection scanning device having high performance and suitable for high speed. By using such a deflection scanning device, it is possible to greatly contribute to the high speed and high performance of the image forming apparatus.

[Brief description of drawings]

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

FIG. 2 is a partial cross-sectional view showing a main part of the device of FIG.

FIG. 3 is a partial sectional view showing a main part of a deflection scanning device according to a modification.

FIG. 4 is a plan view showing a deflection scanning device according to a conventional example.

5 is a schematic cross-sectional view of the deflection scanning device shown in FIG.

[Explanation of symbols]

1 Light source unit 2 rotating polygon mirror 4 lenses 5 folding mirror 10 Optical box 10a side wall 10b bottom wall 20 hollow wall 22,32 ribs

Claims (3)

(57) [Claims] 1. A light source, a light source supporting means for supporting the light source, a rotary polygonal mirror for deflecting and scanning a light beam generated from the light source, and an optical box for housing the rotary polygonal mirror. However, the deflection scanning device is provided with a rigidity strengthening means for locally strengthening the rigidity in the vicinity of the light source supporting means. 2. The deflection scanning device according to claim 1, wherein the rigidity enhancing means has a local double wall structure provided on the side wall of the optical box. 3. The deflection scanning device according to claim 1, wherein the rigidity enhancing means has a local rib structure provided on the bottom wall of the optical box.