JPH05196884A - Laser light scanning device - Google Patents

Abstract

PURPOSE:To facilitate optical adjustments and to sufficiently reduce the influence of the vibration of a polygon motor on an optical system. CONSTITUTION:For example, a 2nd frame 42 where various optical components are arranged is put on a 1st frame 41 consisting of the main frame of a device main body. A fitting hole 44 for a polygon motor 23 is bored in the 2nd frame 42 and while the 2nd frame 42 is moved to a desired position, the polygon motor 23 can be fixed to the 1st frame 41. The polygon mirror 22 fitted to the polygon motor 23 is fitted at a desired position on the 1st frame 41 while maintaining the position relation with the optical components on the 2nd frame 42, so the optical adjustments are easily completed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser beam scanning device used in a copying machine, a printer or the like for recording image information by using a laser beam, and more particularly to a laser beam scanning device using a polygon mirror The present invention relates to a laser beam scanning device.

[0002]

2. Description of the Related Art Laser light scanning devices have come to be widely used in printers and copying machines due to the demand for high image quality and high speed recording. Most of such laser beam scanning devices use a polygon mirror as an optical component for scanning a laser beam on a photoconductor. The polygon mirror is attached to the rotary shaft of a polygon motor, and rotation control is performed at high speed.

FIG. 2 shows a conventional laser beam scanning device used for recording an image on a relatively large size sheet such as a sheet of Japanese Industrial Standard A2 size or larger and its periphery. Is. The photoconductor drum 11 is configured to rotate in the direction of arrow 12 at a constant speed, and is uniformly charged by the charge corotron 13 arranged above the photoconductor drum 11. The surface of the photoconductor after the charging is irradiated with the laser beam 14 to form an electrostatic latent image. The electrostatic latent image is developed by a developing device (not shown), and the toner image obtained by this is transferred to a sheet (not shown).

A laser optical system for irradiating the laser beam 14 is arranged above the photosensitive drum 11. These laser optical systems are attached to the main frame 16 or the sub frame 17. That is, a polygon motor 23 having a polygon mirror 22 mounted on a rotation shaft is fixed by set screws 24 and 25 to a subframe 17 in which optical components such as an Fθ lens 21 and a laser oscillator not shown in this figure are arranged in advance. Has been done. The sub-frame 17 itself is fixed to the main frame 16 by a plurality of setscrews (only two are shown in the figure) 27 and 28. The laser light 14 reflected from a predetermined mirror surface of the polygon mirror 22 passes through the fθ lens 21, is sequentially reflected by the first to third mirrors 31 to 33 attached to the main frame 16, and is then exposed. It reaches on the body drum 11. Of these, the first to third mirrors 31 to 33 are
It is attached to the main frame 16.

In the laser beam scanning device for scanning an image of a relatively large size, the polygon motor 2 is used.
A metal frame having sufficient strength is prepared from the necessity of absorbing the vibration of No. 3 and the like. In the example of FIG. 2, the main frame 16 corresponds to this. The metal frame is also effective in shielding electrical noise generated from the noise source.

On the other hand, the sub-frame in which many peripheral optical systems other than the polygon mirror 22 are arranged is often made of resin in view of both the necessity of accurately arranging these optical parts and the cost. In the following description, the metal frame or the main frame 16 shown in FIG. 2 will be referred to as a first frame, and the subframe 17 will be referred to as a second frame, unless otherwise required.

By the way, the laser beam 14 reflected by the polygon mirror 22 passes through some optical parts such as the fθ lens 21 and the first to third mirrors 31 to 33 and reaches the photosensitive drum 11. The characteristics of these optical components vary to some extent. Therefore, in order to secure a desired beam diameter and scanning magnification on the photoconductor drum 11, it is usual to adjust the conjugate length of the optical system.
In the laser beam scanning device shown in FIG. 2, the first and second mirrors 31 and 32 are simultaneously moved in the direction of arrow 35 in the figure, or the second frame 17 itself is moved in the same direction in the direction of arrow 35 to conjugate the same. I was adjusting the length.

[0008]

By the way, when the first and second mirrors 31 and 32 are simultaneously moved to make such an adjustment, it is not necessary to move the optical system around the polygon mirror 22. . However, when the second mirror 32 is moved, the positional relationship with the third mirror 37 is changed, so that the reflected light of the second mirror 32 is incident on the predetermined position of the third mirror 33 along with this movement. like,
It is necessary to rotate in the direction of arrow 36 by a predetermined angle. The position of the third mirror 37 does not need to be changed, but the direction of the laser beam 14 entering the third mirror 37 is different. It is necessary to rotate the direction by a predetermined angle.

As described above, in the conventional laser light scanning device, the conjugate length is adjusted by adjusting the optical components such as the mirror not only in the linear direction but also in the rotational direction. Therefore, there is a problem that not only the adjustment mechanism becomes complicated, but also the number of adjustments and the cost are increased.

In order to solve such a problem, it has been considered to fix these first to third mirrors 31 to 33 and move the second frame 17 to adjust the conjugate length. In this case, since the second frame 17 only needs to be moved in the linear direction, the adjustment mechanism is simple and the number of adjustment steps is small. However, in this case, it is necessary to fix the polygon motor 23 to which the polygon mirror 22 is attached to the second frame 17.

However, the second frame 17 is often made of resin because it is necessary to accurately arrange various optical components. If the second frame 17 is made of resin, there is a problem that the polygon motor cannot be fixed with sufficient strength. Further, since resin generally has a lower thermal conductivity than metal, there is a problem that it is difficult to radiate the heat generated by the polygon motor 23. Further, regardless of whether it is made of resin or not, fixing the polygon motor 23 directly to the second frame 17 on which various optical components are arranged directly vibrates the optical system, which causes an image disorder. Also occurs.

SUMMARY OF THE INVENTION An object of the present invention is to provide a laser beam scanning device which can easily perform optical adjustment and can sufficiently reduce the influence of the vibration of the polygon motor on the optical system.

[0013]

According to a first aspect of the invention, (a) a polygon mirror for scanning a laser beam;
(B) A polygon motor having this polygon mirror attached to its rotation axis, and (c) a first frame in which the polygon motor can be fixed at an arbitrary position within a preset adjustment range, and (d) The laser beam scanning optical system is arranged on the first frame so as to be overlapped with each other, and at least a part of the laser beam scanning optical system is arranged at each prescribed position. A second frame having a fitting hole for fitting the same to the second frame, and (e) fixing the first and second frames in a desired positional relationship with the polygon motor fitted in the fitting hole. And a frame fixing means for controlling the laser beam scanning device.

That is, according to the first aspect of the present invention, the polygon motor itself is attached to a first frame such as a main frame, and the mounting position on the first frame can be adjusted. In addition, the second such as subframe
The frame is provided with a fitting hole for fitting the polygon motor at the position of the polygon motor determined by the relationship with the optical components arranged on the frame. Since the second frame is arranged on top of the first frame, if the polygon motor is fixed at a desired position on the first frame, the polygon motor is also arranged at a desired position on the second frame. Will be.

[0015]

EXAMPLES The present invention will be described in detail below with reference to examples.

FIG. 1 shows a laser beam scanning device and its periphery in an embodiment of the present invention. This FIG. 1 corresponds to FIG.

Also in the laser beam scanning device of this embodiment, a laser beam scanning device for irradiating the laser beam 14 is arranged above the photosensitive drum 11. The optical components that make up these laser optical systems are divided into a first frame 41, which is a main frame, and a second frame 42, which is mounted on the first frame 41. First frame 4
Reference numeral 1 is an aluminum casting, which constitutes a frame of the main body of the apparatus which accommodates the laser beam scanning apparatus. The polygon motor 23 and the first to third mirrors 31 to 33 are attached to the first frame 41. Among them, the polygon motor 23 has a plurality of columnar pedestals (only two are shown in the figure) 41A and 41B of the first frame 41 and a plurality of set screws (only two are shown in the figure). )
It is fixed by 24 and 25. At the time of this fixing, the polygon motor 23 can adjust its fixing position within a predetermined range.

On the other hand, the second frame 42 is made of resin. At a substantially central position of the second frame 42,
A circular fitting hole 44 that fits accurately with a cylindrical portion forming the lower half of the polygon motor 23 is bored, and the polygon motor 23 is fitted therein. Therefore, the second frame 42 includes a plurality of pedestals 4 of the first frame 41.
1A and 41B are provided with holes (only two are shown in the figure) 45 and 46 that are considerably larger than these outer shapes, and the upper portions of the plurality of pedestals 41A and 41B are located on the second frame 42. It projects more than the surrounding area.

On the second frame 42, an optical element such as a Fθ lens 21 and a laser oscillator (not shown in the figure) is provided on the second frame 42 so as to maintain an optical arrangement relationship with the polygon mirror 22 attached to the polygon motor 23. Parts are placed. A plurality of screw holes (only two are shown in the figure) 47 and 48 are formed in the second frame 42 so that the second frame 42 can be fixed on the first frame 41 by the set screws 51 and 52. It has become.

In the laser beam scanning device configured as described above, the laser beam 14 output from the laser oscillator (not shown) is incident on a specific position of the polygon mirror 22,
It is reflected as shown. The laser beam 14 is then F
The beam passes through the θ lens 21 and becomes a beam having a constant scanning speed of the laser beam at each scanning position of the photosensitive drum 11. The laser beam 14 is emitted from the first mirror 31.
To the desired scanning position of the photoconductor drum 11 by being sequentially reflected by the second mirror 32 and the third mirror 33. The manner of adjusting the conjugate length of the optical system in such a laser beam scanning device will be described below.

First, the operator stacks the second frame 42 on the first frame 41. At this time, the pedestals 41A and 41B are inserted into the holes 45 and 46. After this, the operator fits the polygon motor 23 with the polygon mirror 22 attached to the fitting hole 44. Then, the second frame 42 is moved in the horizontal direction with respect to the first frame 41 in order to adjust the conjugate length of the optical system. When the second frame 42 is moved, the polygon motor 23 moves within its allowable range as the fitting hole 44 moves.

After the adjustment of the conjugate length of the optical system is completed, the set screws 24 and 25 are completely tightened at that point to completely fix the polygon motor 23 to the first frame 41. Then, the set screws 51 and 52 are tightened at this fixing position to completely fix the second frame 42 to the first frame 41. This completes the adjustment of the laser beam scanning device.

Although the second frame is made of resin in the above-described embodiments, it may be made of metal or may be made of resin. Also,
In the embodiment, the pedestals 41A and 41B for mounting the polygon motor 23 have been described as having a cylindrical shape, but may have a prismatic shape or another shape such as a crescent shape.

Further, although the fitting hole 44 is circular in the embodiment, it may have any shape that conforms to the outer shape of the polygon motor 23, and when the second frame 42 is moved, the polygon motor 23 follows it. It may be one in which a part of the shape contacts with high accuracy so as to move. In this sense, the fitting hole 44 may be V-shaped or rectangular. Further, although the polygon motor 23 is completely fixed to the first frame in the embodiment, it is needless to say that only a part thereof may be fixed.

According to the embodiment described above, since the second frame is resin-molded, not only the optical parts of the laser beam scanning device can be arranged on this frame easily and accurately, but also the manufacturing cost is improved. Can also be reduced. Further, in this embodiment, since the first frame is made of metal, heat generated from the polygon motor or the like can be efficiently transmitted to the outside of the laser beam scanning device, and heat generation can be sufficiently suppressed. Moreover, there is an advantage that harmful radio waves are shielded by this.

[0026]

As described above, according to the present invention, since the polygon motor is fixed to the first frame, not only the optical adjustment is simplified, but also the scanning optical system arranged on the second frame is vibrated. I can minimize the transmission,
There is an effect that it is possible to effectively prevent image distortion.

[Brief description of drawings]

FIG. 1 is a side view showing a partial cross-section of a laser beam scanning device and its surroundings in an embodiment of the present invention.

FIG. 2 is a side view showing a conventional laser light scanning device and its surroundings in a partial cross section.

[Explanation of symbols]

14 ... Laser light, 21 ... f.theta. Lens, 23 ... Polygon motor, 24, 25, 51, 52 ... Set screw, 31 ... First
Mirror, 32 ... second mirror, 33 ... third mirror,
41 ... First frame, 42 ... Second frame, 44 ...
Mating hole

Claims (1)

[Claims] 1. A polygon mirror for scanning a laser beam, a polygon motor having the polygon mirror mounted on its rotation axis, and the polygon motor fixed to an arbitrary position within a preset adjustment range. The first frame and the first frame are arranged so as to overlap each other, and at least a part of the scanning optical system of the laser beam is arranged at each prescribed position. A second frame in which a fitting hole for fitting the polygon motor is arranged at a position where the polygon motor should be arranged; and the first and second frames in a state where the polygon motor is fitted in the fitting hole. A laser beam scanning device, comprising: a frame fixing unit that fixes the frame in a desired positional relationship.