JP2653119B2 - Scanner unit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanner unit used for laser light scanning in office machines, video equipment, measuring equipment, and the like.

[Conventional technology]

2. Description of the Related Art Conventionally, as this kind of scanner unit, for example, one having a structure shown in FIG. 2 is used.

One end of the shaft body 2 is fixed to the base 1a of the housing 1, and the sleeve 3 fitted around the shaft body 2 is provided with an inner diameter surface of the sleeve 3 and a groove 4 for generating dynamic pressure. The shaft 2 is supported in the radial direction via a dynamic pressure type radial fluid bearing formed by the outer diameter surface of the shaft body 2. A thrust receiver 5 having an air vent hole 5a is attached to one end of the sleeve 3, and the sleeve 3 has a dynamic pressure formed by an inner surface of the thrust receiver 5 and an end surface of the shaft body 2 opposed thereto. It is supported in the axial direction via a thrust fluid bearing.

The sleeve 3 has a flange 3a.
The lower surface and the upper surface of the polygon mirror 6 fitted to the outer peripheral surface are clamped by a flange 3a and a mounting ring 7a, respectively.

A window 8 made of a transparent material is provided on the side wall 1b of the housing 1 at a position facing the polygon mirror 6 in the horizontal direction.

The upper surface of the rotor magnet 9a fitted to the outer peripheral surface of the sleeve 3 is locked to a step provided below the flange 3a of the sleeve 3 in the axial direction, and the lower surface of the rotor magnet 9a is fixed by a mounting ring 7b. It is pinched. The stator coil 9b radially opposed to the rotor magnet 9a is attached to the side wall 1c of the housing 1, and the rotor magnet 9a and the stator coil 9b constitute a drive motor having a peripheral surface facing type.

When the sleeve 3 is supported on the shaft body 2 and rotated by the operation of the drive motor, the scanner unit described above rotates the polygon mirror 6.
The laser beam incident on the target is reflected, passes through the window 8, and irradiates a target (not shown) such as a photosensitive drum placed outside.

[Problems to be solved by the invention]

The above-described scanner unit has a structure in which a rotating member including the scanner 3 and attached parts such as the polygon mirror 6 and the rotor magnet 9a rotates around the shaft body 2 which is a stationary member. In such a case, it is indispensable to correct the weight imbalance in the radial direction of the rotating member.

However, the correction of the weight imbalance in the radial direction of the rotating member is performed by holding the sleeve 3 to which the accessory such as the polygon mirror 6 is attached in a horizontal state, supporting the outer diameter surfaces at both ends in the axial direction, and supporting the center axis. , The outer diameter surface of the sleeve 3 becomes a reference.

On the other hand, since the rotation of the rotating member when the scanner unit is used is based on the inner diameter surface, it is necessary to process the coaxiality of both the outer diameter surface and the inner diameter surface of the sleeve 3 with high accuracy, and the processing cost is high. Disadvantage.

Further, the radial bearing and the thrust bearing formed between the sleeve 3 and the shaft body 2 are hydrodynamic gas bearings, and a gas such as air is used as a lubricating fluid. During the rotation, the sleeve 3 rotates in a non-contact state with respect to the shaft body 2 due to the pumping action of the dynamic pressure generating groove 4 on the outer diameter surface of the shaft body 2. The sleeve 3 and the shaft 2 come into contact with each other. However, gas such as air used as a lubricating fluid is inferior in lubricating performance as compared with other lubricants. The surface and the thrust bearing surface of the thrust bearing 5 will be greatly damaged.

Therefore, in order to prevent such damage to the bearing surface, the sleeve 3 is formed by applying a coating such as plating having excellent slidability to the surface of a cut metal material, and using a thrust bearing 5.
Similarly, a synthetic material having excellent slidability and integrated by injection molding on the surface of a cut metal material is used.

However, the sleeve 3 and the thrust receiver 5 having been subjected to such surface treatment not only increase the cost, but also because the sleeve 3 and the thrust receiver 5 are separate bodies, the press-fitting, shrink fitting, and the like are performed. In addition to the necessity of assembling, there is a drawback that assembling with high precision requires considerable trouble.

The present invention has been made for the purpose of eliminating the various disadvantages as described above.

[Means for solving the problem]

In the scanner unit according to the present invention, the cylindrical hole of the inner cylinder made of synthetic resin integrally formed with the inner surface of the outer cylinder made of metal has a radial bearing surface and a thrust bearing surface, and is rotatably arranged in the cylindrical hole. The provided shaft body has a radial receiving surface facing the radial bearing surface and a thrust receiving surface facing the thrust bearing surface, and the dynamic pressure generation provided on at least one of the radial bearing surface and the radial receiving surface is provided. The dynamic pressure type radial gas bearing is constituted by the groove for use.

A polygon mirror fitted to the shaft is clamped and fixed between the flange provided at the end of the shaft opposite to the thrust receiving surface and the yoke to which the rotor magnet is attached. , And a stator coil is disposed.

[Action]

In the scanner unit of the present invention, since the shaft body as the rotating member is disposed in the cylindrical hole of the inner cylinder as the stationary member,
There is no need to machine the coaxiality between the inner diameter surface of the cylindrical hole and the outer diameter surface of the outer cylinder with high precision.

In addition, since the radial bearing surface and the thrust bearing surface of the cylindrical hole are integrally formed of synthetic resin, damage to the bearing surface when starting and stopping the shaft body is reduced, and assembling work is not required. The required accuracy is easily ensured.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIG.

The housing 10 has a structure in which an upper wall member 12 and a sleeve member 13 are air-tightly joined to a side wall member 11, respectively, and a gas such as air is sealed inside the housing 10.

The sleeve member 13 of the housing 10 includes an outer cylinder 13a made of a metal such as an aluminum alloy or a zinc alloy, and an inner cylinder 13b made of a synthetic resin integrally formed on the inner surface of the outer cylinder 13a. The inner cylinder 13b is composed of a cylindrical body 13c and a bottom 13d.The outer cylinder 13a having an inner peripheral surface coated with an adhesive is placed in a molding die, and the outer cylinder 13 is formed by injection molding a synthetic resin material.
The inner cylinder 13b is adhered to the inner surface of. The body of this inner cylinder 13b
The inner peripheral surface of the cylindrical hole 14 formed in 13c is the radial bearing surface 1.
5, a groove for generating dynamic pressure (not shown) is formed on the radial bearing surface 15 by a mold at the time of injection molding. Inner cylinder 13
At the bottom 13d of b, a thrust bearing surface 16 having a convex spherical projection 16a at the center is provided, and a throttle hole 17 provided on the axial center line of the bottom 13d is opened at the center of the thrust bearing surface 16. doing.

As a molding material for the inner cylinder 13b of the sleeve member 13, it is preferable to use a synthetic resin having excellent self-lubricating properties.

Also, on the bottom surface of the sleeve member 13, an elastic member
A holding member 19 is hermetically attached via 18, and a gap 20 formed between the sleeve member 13 and the holding member 19 is
The communication groove 21 formed between the outer peripheral surface of 13 a and the inner peripheral surface of the side wall member 11 communicates with each other.

In the cylindrical hole 14 of the sleeve member 13, a shaft body 30 provided with a flange portion 31 at the upper end is provided. On the outer peripheral surface of the shaft body 30, a radial receiving surface 35 facing the radial bearing surface 15 is provided.
A thrust receiving surface 36 facing the thrust bearing surface 16 is provided on the end surface of the shaft body 30. The thrust receiving surface 36
A pressure chamber 37 is formed in a space between the outer peripheral portion of the thrust bearing surface 16 and the outer peripheral portion of the thrust bearing surface 16.

The center of the thrust receiving surface 36 of the shaft 30 is an annular contact surface 36a that comes into contact with the raised portion 16a of the thrust bearing surface 16 when the shaft 30 is stationary.

The material of the shaft body 30 is preferably an aluminum alloy which is light and hard to rust and has good workability, or a material obtained by subjecting the surface of the aluminum alloy to a hardening treatment, but stainless steel may be used.

The polygon mirror 40 fitted on the outer peripheral surface of the shaft 30 is
The upper and lower surfaces are attached to each other by a flange portion 31 and a yoke 41. An annular rotor magnet 42 is attached to the yoke 41, and a stator coil 43 fitted and attached to the sleeve member 13 of the housing 10 faces the rotor magnet 42 in the radial direction.

A window 11a made of a transparent material is provided in the side wall member 11 of the housing 10 at a position facing the polygon mirror 40 in the horizontal direction.

A circumferential groove 38 is provided on the upper side surface 31a of the shaft body 30, and the yoke 4
At the mounting portion with the polygon mirror 40, through holes 44 are provided at a plurality of positions in the circumferential direction, and an adhesive for correcting the weight imbalance in the radial direction is applied to these circumferential grooves 38 and the through holes 44. I am doing it.

In the scanner unit having the above configuration, when the shaft body 30 rotates, a pumping action is generated by the grooves for generating dynamic pressure provided on the radial bearing surface 15, and the gas in the housing 10 is brought into contact with the radial bearing surface 15 and the radial bearing surface. It is sucked into the radial gap between the surface 35 and flows into the press-fitting chamber 37, and the shaft 30 floats by the gas pressure in the pressure chamber 37. When the shaft 30 rises, the throttle hole 17 opens in the pressure chamber 37, and the gas flowing into the pressure chamber 37 rises through the flow groove 21 through the gap 20 from the throttle hole 17 and is discharged into the housing 10. The gas pressure in the pressure chamber 37 is appropriately adjusted by the floating amount of the shaft 30, and the shaft 30 rotates by the gas pressure while maintaining a constant floating amount.

When the shaft 30 is stationary, the contact surface 36a at the center of the thrust receiving surface 36 of the shaft 30 is in contact with the convex spherical surface of the raised portion 16a of the thrust bearing surface 16, so that the starting torque at the time of starting is small, and Even if the finishing accuracy of the thrust receiving surface 36 of the shaft body 30 is somewhat inferior, no one-side contact occurs.

Further, at the time of starting and stopping of the shaft body 30, since the synthetic resin forming the radial bearing surface 15 and the thrust bearing surface 16 of the sleeve member 13 comes into contact with the shaft body 30, damage to these bearing surfaces 15, 16 is reduced. However, as described above, when the inner cylinder 13b is formed using a synthetic resin having good self-lubricating properties, damage to the bearing surfaces 15, 16 at the time of starting and stopping can be further reduced.

Further, since the rotor magnet 42 and the stator coil 43 that constitute the drive motor are of a peripheral surface facing type, the attraction force between them does not act as a thrust load, thus preventing the thrust bearing surface 16 from being worn. It is helpful.

In the above embodiment, the groove for generating dynamic pressure provided on the radial bearing surface 15 of the sleeve member 13 is provided on the radial receiving surface of the shaft body 30.
35, the radial bearing surface 15 and the radial bearing surface 35
May be provided for both.

Further, a groove for generating a dynamic pressure may be provided on at least one of the thrust bearing surface 16 of the sleeve member 13 and the thrust receiving surface 36 of the shaft body 30 to form a so-called flat group bearing. In such a case, the throttle hole 17 provided in the thrust bearing surface 16 can be omitted.

In the above embodiment, the side wall member 11 of the housing 10 and the outer cylinder 13a
However, the side wall member 11, the outer cylinder 13a, and the outer cylinder 13a may be formed as an integral part by die casting. In this case, the number of components is reduced and the assembling work is simplified.

In the above embodiment, the flange portion 31 of the shaft body 30 is integrally formed with the shaft portion by die casting, forging, cutting, or the like. However, a separate flange portion is fixed to the shaft portion by press-fitting or shrink fitting. May be.

In addition, between the polygon mirror 40 attached to the shaft body 30 and the yoke 41, a thin sheet member made of a nonmetal such as metal or synthetic resin is used to reduce deformation when the polygon mirror 40 is fixed. It may be sandwiched.

Also, instead of providing the throttle hole 17 in the inner cylinder 13b, a shaft 30
An axial hole passing through both end surfaces 31a, 36 of the shaft 30 is provided at the axis of the shaft, the axial hole is opened at the center of the thrust receiving surface 36 and the upper surface 31a of the shaft and A flow hole having a larger inner diameter than the throttle hole may be provided.

By doing so, the throttle holes 17 of the inner cylinder 13b for gas circulation,
Since the flow groove 21, the elastic member 18, and the pressing member 19 can be omitted, the cost is reduced. In addition, the axial hole of the shaft body 30 can increase the inside diameter of a portion other than the throttle hole, so the shaft body 30
As a result, the thrust load can be reduced and the thrust bearing surface 16 can be prevented from being damaged. Further, by applying an adhesive or the like to the inner peripheral surface of the axial hole of the shaft
The imbalance of the weight in the radial direction of the rotating member provided with can be corrected.

Further, when a sheet-shaped member made of a synthetic resin having excellent slidability is attached to the thrust bearing surface 16 separately from the inner cylinder 13b, or the inner cylinder 13b and the sheet-shaped member are integrally formed. Even if the slidability of the radial bearing surface 15 is somewhat inferior, it is possible to use a synthetic resin as the material of the inner cylinder 13b, which can easily ensure dimensional accuracy during injection molding.

The housing 10 itself may be a scanner unit having a non-closed structure, and this unit may be housed in another device having a closed structure.

〔The invention's effect〕

As described above, in the scanner unit of the present invention, since the shaft is rotatably disposed in the cylindrical hole of the inner cylinder, which is a stationary member, a sleeve is provided around the fixed shaft as in the related art. Unlike the rotatable scanner unit, the sleeve member having the outer cylinder and the inner cylinder, which are stationary members, does not require the work of correcting the weight imbalance in the radial direction. It is not necessary to process the coaxiality with high precision, and the processing cost is reduced.

Further, in the present invention, since the radial bearing surface and the thrust bearing surface provided in the cylindrical hole are integrally formed of a synthetic resin, not only the damage to each bearing surface when starting and stopping the shaft body is reduced, but also This eliminates the need for assembling work, which was necessary for the conventional case where the sleeve and the thrust bearing are separated from each other, improving mass productivity and ensuring the required accuracy such as the perpendicularity between bearing surfaces. It will also be easier to do.

In the present invention, since the cylindrical hole of the inner cylinder made of synthetic resin integrally formed with the inner surface of the outer cylinder made of metal has a radial bearing surface, the required accuracy of the radial bearing surface is reduced by injection molding. When the temperature of the bearing portion is easily secured and the temperature of the bearing portion rises during use, the expansion of the synthetic resin is suppressed by the outer cylinder made of metal, so that the change in the inner diameter of the radial bearing surface is reduced.

Further, in the present invention, since the polygon mirror is clamped and fixed by the flange provided at one end of the shaft and the yoke to which the rotor magnet is attached, the mounting accuracy of the polygon mirror to the shaft is increased. At the same time, mounting work can be done easily, and a special mounting member for the polygon mirror is not required.
The number of parts is reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view showing an embodiment of the present invention, and FIG. 2 is a longitudinal sectional side view showing a conventional scanner unit. In the drawing, 10 is a housing, 13 is a sleeve member, 13a and 13b are outer and inner cylinders of the sleeve member, 15 is a radial bearing surface, 16 is a thrust bearing surface, 30 is a shaft, and 31 is a flange of the shaft. , 35 are a radial receiving surface, 36 is a thrust receiving surface, 40 is a polygon mirror, 41 is a yoke, 42 is a rotor magnet, and 43 is a stator coil.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-9717 (JP, A) JP-A-61-296325 (JP, A) JP-A-60-222620 (JP, A)

Claims (1)

(57) [Claims] A cylindrical hole of an inner cylinder made of synthetic resin integrally formed with an inner surface of an outer cylinder made of metal has a radial bearing surface and a thrust bearing surface, and is rotatably disposed in the cylindrical hole. The shaft body has a radial receiving surface facing the radial bearing surface and a thrust receiving surface facing the thrust bearing surface, and at least one of the radial bearing surface and the radial receiving surface is provided with a groove for generating dynamic pressure. To form a dynamic pressure type radial gas bearing,
A polygon mirror fitted to the shaft is clamped and fixed between the flange provided at the end of the shaft opposite to the thrust receiving surface and the yoke to which the rotor magnet is attached, and faces the rotor magnet. A scanner coil, wherein a stator coil is provided.