JPH06347716A - Polygon mirror scanner device - Google Patents

Abstract

PURPOSE:To stabilize the thrusting pressure and to improve the accuracy mainly against the deviation of the position of an optical scanning line and nonuniform density by pressing a polygon mirror by means of a ring-like member while decreasing the ratio of compressing load to the compressive displacement in the direction of rotating center of the polygon mirror. CONSTITUTION:A receiving base 32 having a cylindrical part is fixed on the rotary shaft of a motor 21. A polygon mirror 31 whose inner peripheral surface is engaged with the cylindrical part of the receiving base 32 is provided on the receiving base 32. A ring-like member 41a is engaged with the periphery of the protruded part from the cylindrical part of the receiving base 32. The ring-like member 41a having a recessed groove is a member for pressing the polygon mirror and made of aluminum. When the inner periphery of the member is put on the tip of the cylindrical part of the receiving base 32 and fixed by a screw 23, the ring-like member 41a is elastically deformed and the polygon mirror 31 is held vertically between the ring-like member 41a and the receiving base 32. Consequently, the variation of the thrusting pressure holding an individual polygon mirror is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polygon mirror scanner device, and more particularly to a polygon mirror scanner device which uses a polygon mirror and is highly accurate and stable.

[0002]

2. Description of the Related Art Conventionally, in a digital copying machine, a laser beam printer or the like, for example, a polygon mirror of a rotary polygon mirror is irradiated with laser light, and the laser light reflected by a rotating rotary polygon mirror is transmitted through a lens to form a photosensitive drum. It is configured to project while scanning.

In recent years, digital information devices are required to have high-speed and high-quality performance, and polygon mirror scanner devices are also required to have high precision and good stability.

Therefore, the following techniques have been disclosed conventionally.

1) As a device for holding a polygon mirror, one having a structure in which a seat for receiving the polygon mirror and a ring-shaped member for holding the polygon mirror are sandwiched from above and below to fix the polygon mirror, as shown in FIG. 9A. Is disclosed (see Japanese Utility Model Publication No. 61-94811).

As shown in the figure, there is one in which a seat 400a for receiving the polygon mirror 200a is provided on the rotating shaft of the motor 100, and an elastic ring-shaped member 300a for holding the polygon mirror 200a is provided.

Since the elastic member is pressed by the elastic rubber material, the polygon mirror can be pressed uniformly. However, the compression displacement amount of the ring-shaped member 300a also changes due to the stacking error in the vertical dimension of the seat 400a, the polygon mirror 200a, and the ring-shaped member 300a. As seen from the examples, since the elastic body is pressed by compression with a thin elastic body, the force for pressing the polygon mirror is likely to vary when producing a large number of polygon mirror scanner devices. Further, if the ratio of the compression load to the compression change position is high, the load change that holds down the polygon mirror due to the change over time of the material or the like is large, and the accuracy of the polygon mirror may be deteriorated. Further, in order to fix the polygon mirror, it seems necessary to lock the ring-shaped member to the groove with a dedicated jig.

2) Next, as another device for holding the polygon mirror, as shown in FIG. 9B, one having a structure substantially similar to that shown in FIG. -3
(See Japanese Patent No. 815). As shown in the drawing, there is one in which a receiving seat 400b for receiving the polygon mirror 200b is provided on the rotating shaft of the motor 100, and a ring-shaped member 300b made of an elastic material for holding the polygon mirror 200b is provided.

Since it is pressed by an elastic rubber material or the like, the polygon mirror 200b can be pressed uniformly. However, since the pressing pressure of the polygon mirror is mainly generated by the compressive displacement of the claw-shaped projection at the narrow portion of the tip of the motor rotation shaft 800b, the load for pressing the polygon mirror is likely to fluctuate. Further, as in the case of FIG. 9A, it seems that a dedicated jig is required to fix the ring-shaped member 300b.

3) Furthermore, FIG. 10A shows a method for correcting the rotation imbalance with respect to the rotation center of the polygon mirror.
As shown in, there is one in which a hole 500 is formed in the polygon mirror 200c with a drill or the like. Although the imbalance can be corrected, there is a problem that the plane accuracy of the mirror surface and the tilt angle accuracy of the mirror surface are deteriorated.

4) Further, as a correction of the imbalance with respect to the rotation center of the polygon mirror, there is a polygon mirror 200d provided with a circular concave groove 700, and a heavy object 600 is partially added to the concave groove.

However, it is not preferable to process a concave groove such as a ring shape in a polygon mirror which requires high precision because it may cause distortion due to the processing and may disturb the internal stress balance of the material.

[0013]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the invention of claim 1 reduces variations in the pressing pressure for holding individual polygon mirrors and reduces the pressing pressure. It is an object of the present invention to provide a polygon mirror scanner device which is stabilized over time and mainly has improved accuracy with respect to positional deviation of optical scanning lines and density unevenness.

Further, according to the invention of claim 2, the precision of the polygon mirror alone is not affected, and the rotation imbalance with respect to the polygon mirror rotation center is corrected integrally with the pressing of the polygon mirror, and the optical scanning line is mainly used. It is an object of the present invention to provide a polygon mirror scanner device which is improved in accuracy with respect to the positional deviation and the density unevenness.

Further, according to the invention of claim 3, the variation of the pressing pressure for holding the individual polygon mirrors is reduced, the pressing pressure is stabilized over time, and the accuracy of the polygon mirror is not affected. It is an object of the present invention to provide a polygon mirror scanner device which is configured to correct rotational imbalance with respect to a polygon mirror rotation center integrally with a pressing member and mainly improve accuracy of positional deviation of optical scanning lines and density unevenness.

Further, the invention of claim 4 is the same as that of claim 3 above.
It is an object of the present invention to provide a ring-shaped member used to achieve the object of the invention.

[0017]

The above object can be achieved by the following means. That is, (1) a polygon mirror scanner in which a polygon mirror is provided on a seat fixed to a rotation shaft of a motor, and the polygon mirror is sandwiched and held between the seat and a ring-shaped member that holds the polygon mirror. In the apparatus, there is provided a polygon mirror scanner device characterized in that the ring-shaped member lowers a ratio of a compression load to a compression displacement amount in a rotation direction of a polygon mirror to press the polygon mirror. A polygon mirror is provided on the receiving seat fixed to the holding member, and the polygon mirror is sandwiched and held between the receiving seat and a ring-shaped member that holds the polygon mirror, and the rotational imbalance of the polygon mirror is corrected. In the polygon mirror scanner device having, the polygon mirror is rotated by the ring-shaped member. A polygon mirror scanner device characterized by being capable of correcting rotational imbalance with respect to a heart. In the polygon mirror scanner device according to item (3) 1, the rotational imbalance with respect to the polygon mirror rotational center line is corrected by the ring-shaped member. (4) A ring-shaped member provided in a polygon mirror scanner device having a polygon mirror, wherein the ring-shaped member is a compressive load with respect to a compression displacement amount in a rotation center direction of the polygon mirror. The ring-shaped member is characterized in that it is possible to suppress the polygon mirror by pressing the polygon mirror at a low ratio while correcting the rotational imbalance with respect to the rotation center of the polygon mirror.

The term "ring-shaped member" as used herein means a ring-shaped member having a pressing member for fixing the polygon mirror and / or a correction unit for rotational imbalance with respect to the rotation center of the polygon mirror.

The "compressive load ratio to the compression displacement amount of the ring-shaped member" means the amount by which the ring-shaped member is compressed and displaced in the thrust direction of the rotation center of the polygon mirror in order to press the polygon mirror, and the thrust direction. Means the ratio with the load generated by compression.

Further, "correction of rotation imbalance with respect to the polygon mirror rotation center" means that the rotation imbalance with respect to the rotation center of the polygon mirror of the rotating system including the polygon mirror is punched or a weight is added. Means to correct.

Further, "polygon mirror scanner device"
The term means a scanner device that has at least a polygonal mirror of a rotating polygon mirror used in a copying machine, a printer, etc. and performs optical scanning, and is generally configured with an fθ lens, a cylindrical lens, a reflection mirror, and the like. A laser emitting unit may also be included.

[0022]

The operation of claim 1 will be described. With the above structure, the ring-shaped member reduces the compression load ratio with respect to the compression displacement amount by the ring-shaped member, and further prevents the stress concentration on the polygon mirror side due to the deformation on the ring-shaped member side. Compressive displacement can be performed more sufficiently than before, and the compression load can be reduced in each device, and more stable than before with respect to dimensional changes of related members and elastic properties of ring-shaped members. To work. Further, as the ring-shaped member, a ring-shaped groove may be formed on aluminum metal so as to have elasticity partially, or the above-described groove may be formed by using various plastic materials.

The operation of claim 2 will be described. With the above configuration, the rotation imbalance with respect to the polygon mirror rotation center is corrected integrally with the pressing of the polygon mirror. Therefore, the accuracy of the polygon mirror itself is not adversely affected, and the ring-shaped member has a relatively large area. It works to maintain a well-balanced rotation by correcting with higher accuracy than the rotation imbalance in. As a means for correcting the imbalance with the ring-shaped member, it is preferable to make a hole with a drill or the like to reduce the weight. Further, the ring-shaped member may be provided with concave grooves in a circular shape to fix a heavy object. As the ring-shaped member, the upper part may be made of metal such as aluminum to correct unbalance due to perforation, and the lower part may be pressed by the elastic material such as synthetic rubber to hold the polygon mirror.

Further, a plastic material such as PBT is used.
(Polyptyrene / terephthalate) may be molded, synthetic rubber, natural rubber or the like may be used.

The operation of claim 3 will be described. With the above structure, the ring-shaped member reduces the compression load ratio with respect to the amount of compressive displacement of the polygon mirror, prevents stress concentration on the polygon mirror side due to deformation on the ring-shaped member side, and integrates with the pressing member. Since the rotational imbalance with respect to the rotation center of the polygon mirror is corrected, the ring-shaped member can be compressed and displaced more sufficiently than before, and the compression load can be reduced in each device. The stability of the elastic properties of the ring-shaped member is maintained as compared to the conventional one, and the accuracy of the polygon mirror itself is not adversely affected, and the rotational imbalance of the ring-shaped member over a relatively large area is corrected with high accuracy. It works to maintain a well-balanced rotation.

The operation of claim 4 will be further described. With the above construction, the polygon mirror can be stably held in the same manner as described in the operation of claim 3, and the rotational imbalance with respect to the rotation center of the polygon mirror can be corrected smoothly.

[0027]

Embodiments Embodiment 1, Embodiment 1 and a modification of Embodiment 1, Embodiment 2 and a modification of Embodiment 2 will be described with reference to the drawings.

(Embodiment 1) FIGS. 1A and 1B are a schematic plan view and a sectional view of a polygon mirror scanner device of a copying machine. A polygon mirror scanner device 10 as shown in FIG.
Output light from a semiconductor laser (not shown) is reflected by a polygon mirror 31 through a collimator unit 12 and a cylindrical lens 13, and an fθ lens 14 and a cylindrical lens 15
After that, the light is reflected by the reflection mirror 16 and is applied to a photosensitive drum (not shown).

FIG. 2 is a sectional view of the essential parts of an embodiment of the polygon mirror holding part. As shown in FIG. 2, a receiving seat 32 having a cylindrical portion is fixed to the rotation shaft of the motor 21. The seat 32
A polygon mirror 31 is provided on the upper surface of the polygon mirror 31 with its inner peripheral surface fitted to the cylindrical portion of the seat 32. A ring-shaped member 41a is fitted around the portion of the seat 32 projecting from the columnar portion.

The ring-shaped member 41a is a member for pressing the polygon mirror having the concave groove 43 and is made of aluminum. Then, the ring-shaped member 41a has its inner peripheral edge fixed to the tip of the columnar portion of the seat 32 with the application screw 23,
After being elastically deformed, the polygon mirror 31 is sandwiched by the ring-shaped member 41a and the seat 32 from above and below.

A ball bearing, an oilless metal, an air bearing or the like is used for the rotary bearing (not shown) of the motor 21.

FIG. 3 is an explanatory diagram showing the relationship between the compressive displacement and the compressive load in the ring-shaped member. The horizontal axis represents the compression displacement (δ) and the vertical axis represents the compression load (f). In the figure, the N line shows the present invention, and the M line shows an example of the prior art. Explaining the N line of the present invention, the compressive load increases when the ring-shaped member is brought into contact with the polygon mirror and compressed. The PN point is the position where the ring-shaped member is set, the compression displacement is PNδ and the compression load is PNf. The change in compression displacement is represented by ΔNδ, and the change in compression load is represented by ΔNf. Similarly, regarding the M line, the PM point is the position where the ring member is set, and is the compression displacement PMδ and the compression load change PMf, which are represented by the change ΔMδ in compression displacement and the change ΔMf in compression load, respectively.

Here, in the embodiment of the invention, the change ΔN in the compressive load is caused even if there is an error in the related parts, deformation over time, or the like.
Since f is small, the deformation of the polygon mirror against external pressure can be small. On the other hand, if the conventional one is assumed to have the same change ΔMδ as ΔNδ, ΔMf changes greatly and the accuracy with respect to the external pressure applied to the polygon mirror tends to decrease.

(Modification of First Embodiment) A modification of the first embodiment is composed of a portion which is elastically deformed and a portion which is not deformed as a ring member, and a modification is shown in FIG.

As shown in FIG. 4, the elastically deformable portion 411b has a large outer diameter and a large height in order to keep the compressive load against the amount of compressive displacement low. The material may be synthetic rubber, natural rubber or the like as long as it has elasticity and little change over time. The non-elastically deformable portion 412b is a fitting hole for the seat 32, a screw receiving surface, and an elastically deformable portion 411b.
And the like. With the above configuration, the polygon mirror can be stably pressed.

(Embodiment 2) FIG. 5 is a sectional view of an embodiment having a polygon mirror holding portion and an unbalance correction portion. Since FIG. 5 has almost the same configuration as FIG. 2, a description will be given focusing on the different configuration, and the ring-shaped member 42a has a correction hole 45 for correcting the imbalance. The concave groove 44 is a groove for producing elasticity.

FIG. 6 is a sectional view of the ring-shaped member 42a. The shapes are a = 1 mm, b = 1 mm, c = 3 mm, d1 =
33mm, d2 = 21mm, h = 7.5mm, and the material is aluminum.

FIG. 7 is an explanatory view of changes in the tilt angle of the polygon mirror with respect to the compressive load of the ring-shaped member 42a. The horizontal axis shows the screw tightening torque T as a substitute characteristic value of the compression load, and the vertical axis shows the maximum difference Δθ of the tilt angles of the eight-sided polygon mirror. In the figure, “Δ” indicates a ring-shaped member of the present invention (FIG. 6), and “□” indicates a comparative example in which the ring-shaped member has no concave groove. As shown in the figure, the embodiment of the present invention has a maximum inclination angle difference Δθ with respect to the same screw tightening torque T as compared with the comparative example.
Is small. This is because the non-uniform pressure bonding of the contact portion between the polygon mirror and the ring-shaped member is absorbed by the deformation of the ring-shaped member side to prevent the deformation of the polygon mirror side.

(Modification of Embodiment 2) A modification of Embodiment 2 is a ring-shaped member composed of an elastically deformable portion and an elastically non-deformable portion. A modified example is shown in FIG. An elastically deformable portion 421b of the ring-shaped member 42b as shown in FIG.
Is the same as 411b in FIG. 5, and detailed description thereof will be omitted. Further, the elastically non-deformable portion 422b can be provided with a fitting hole for receiving a seat, a screw receiving surface and a holding hole for the elastically deformable portion 421b, and a correction hole for correcting imbalance with respect to the polygon mirror rotation center. There is.

With the above-mentioned structure, the imbalance can be corrected while the polygon mirror is stably pressed and the accuracy of the polygon mirror is not lowered. In addition,
The concave groove may be provided in a circular shape and overlapped with a metal piece.

[0041]

Since the above-mentioned structure is adopted, the following effects can be obtained.

As an effect of the first aspect, the variation of the pressing pressure for holding the individual polygon mirrors is reduced, the pressing pressure is stabilized with time, and the accuracy of the positional deviation of the optical scanning line and the density unevenness is mainly improved. Be peeled off.

Further, as an effect of claim 2, the precision of the polygon mirror alone is not affected, and the rotational imbalance with respect to the polygon mirror rotation center is corrected integrally with the pressing of the polygon mirror so that the optical scanning line is mainly used. The accuracy of misalignment and uneven density can be improved.

Further, the effect of claim 3 is that the variation of the pressing pressure for holding the individual polygon mirrors is reduced, the pressing pressure is stabilized over time, and the accuracy of the polygon mirror is not affected. The rotational imbalance with respect to the rotation center of the polygon mirror is corrected integrally with the pressing, so that the accuracy of the positional deviation of the optical scanning line and the density unevenness can be mainly improved.

The effect of claim 4 is a ring-shaped member that achieves the effect of claim 3.

[Brief description of drawings]

FIG. 1 is a schematic plan view and a sectional view of an embodiment of a polygon mirror scanner position according to the present invention.

FIG. 2 is a cross-sectional view of a main part of a second embodiment.

FIG. 3 is an explanatory diagram showing a relationship between a compressive displacement and a compressive load in the ring-shaped member.

FIG. 4 is a cross-sectional view showing a modified example of the ring-shaped member of the first embodiment.

FIG. 5 is a cross-sectional view of a main part of the second embodiment.

6 is a cross-sectional view of the ring-shaped member of FIG.

FIG. 7 is an explanatory diagram of changes in the tilt angle of the polygon mirror with respect to the screw tightening torque of the ring-shaped member.

FIG. 8 is a cross-sectional view showing a modified example of the ring-shaped member of the second embodiment.

FIG. 9 is a cross-sectional view showing a polygon mirror holding portion of a conventional polygon mirror scanner device.

FIG. 10 is a sectional view of a polygon mirror showing correction of imbalance of a conventional polygon mirror scanner device.

[Explanation of symbols]

 10 polygon mirror scanner device 21 motor 23 screw 31 polygon mirror 32 seat 41a, 41b ring-shaped member 42a, 42b ring-shaped member 43 concave groove 44 concave groove 45 correction hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Horiai Konica stock company, 2970 Ishikawa-cho, Hachioji, Tokyo (72) Inventor Takami Hashimoto 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock, company

Claims (4)

[Claims] 1. A polygon mirror scanner in which a polygon mirror is provided on a seat fixed to a rotation shaft of a motor, and the polygon mirror is sandwiched and held between the seat and a ring-shaped member for pressing the polygon mirror. In the apparatus, the polygon mirror scanner device is characterized in that the ring-shaped member lowers the ratio of the compression load to the compression displacement amount in the direction of the rotation center of the polygon mirror to press the polygon mirror. 2. A polygon mirror is provided on a seat fixed to a rotating shaft of a motor, and the polygon mirror is sandwiched and held between the seat and a ring-shaped member for pressing the polygon mirror, and the polygon mirror is provided. A polygon mirror scanner device having a correction of rotational imbalance with respect to a mirror rotation center, wherein the ring-shaped member can correct rotational imbalance with respect to a polygon mirror rotation center. 3. The polygon mirror scanner device according to claim 1, wherein the ring-shaped member can correct a rotational imbalance with respect to a polygon mirror rotation center. 4. A ring-shaped member provided in a polygon mirror scanner device having a polygon mirror, wherein the ring-shaped member reduces the ratio of the compression load to the compression displacement amount in the direction of the rotation center of the polygon mirror, A ring-shaped member, characterized in that it can be pressed and corrected for rotational imbalance with respect to the rotation center of the polygon mirror.