JPH03107913A - Deflection scanner incorporating dynamic pressure fluid bearing - Google Patents

Abstract

PURPOSE:To attain miniaturization and light weight and also, low cost by reducing the number of components by coupling the fixing member of a dynamic pressure fluid bearing with the motor substrate of a driving motor, and fixing the motor substrate at a housing container. CONSTITUTION:The fixing member of the dynamic pressure fluid bearing (a fixing sleeve 11 and a fixing shaft) is coupled with the motor substrate 10 of the driving motor 4, and the motor substrate 10 is directly fixed on the housing container. Thereby, no motor case, etc., is required, and the miniaturization and light weight of the deflection scanner using the dynamic pressure fluid bearing can be attained. Furthermore, since the number of components can be reduced, the automatization of assembling can be easily performed, and also, a manufacturing cost can be reduced.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a deflection scanning device using a rotating device such as a polygon mirror supported by a hydrodynamic bearing. This invention relates to a deflection scanning device used for.

[Prior Art] In recent years, there has been an increasing demand for rotating devices that rotate at high speed or with high precision. Particularly in laser beam printers and the like, hydrodynamic bearings that rotate without contact have been used to obtain high-precision rotating devices. is used.

FIG. 5 shows a deflection scanning device for a laser beam printer using such a hydrodynamic bearing. In the figure, a rotating polygon mirror 101 is fixed to a flange 102a of a sleeve-shaped rotor 102 with a hollow center.
Further, a driving magnet 103 is fixed with an adhesive or the like, and a stator coil 104 provided around the driving magnet 103 rotates the rotor 102 and the like. Further, a thrust plate 105 for supporting thrust pressure is provided at the upper part of the rotor 102, and a small diameter hole 106 passes through the center of the thrust plate 105.

On the other hand, a fixed shaft 107 is inserted into the cavity of the rotor 102, and a shallow groove 1 for generating dynamic pressure is formed on the outer periphery of the shaft 107.
078 is formed. The fixed shaft 107 is fixed to a motor case 108, and the stator coil 104 is fixed to the motor case 108.

A cap 109 is fitted to the other end of the motor case 108, and the motor case 108 is further fixed to an optical box 110. In this way, a laser beam from a light source (not shown) is deflected and scanned by the polygon mirror 101 rotating together with the rotor 102, etc., and then an image is formed on the surface of the photosensitive drum 112 by the imaging lens group 111a111b attached to the optical box 110. be done.

[Problems to be Solved by the Invention] However, the above conventional example has the following drawbacks when used as a deflection scanning device.

(1) The rotating device using a hydrodynamic bearing is the motor case 1.
08, it is difficult to make the deflection scanning device smaller and lighter.

(2) Since the guitar case 108 and the like are used, the number of parts increases and the assembly cost of the deflection scanning device increases.

Therefore, in view of the above-mentioned problems, an object of the present invention is to provide a deflection scanning device having a structure that reduces the number of parts, makes it possible to reduce the size and weight, and is also inexpensive.

[Means for Solving the Problems] In order to achieve the above object, the present invention uses a dynamic pressure fluid bearing (composed of a fixed member and a movable member) to replace a deflector such as a polygon mirror that deflects a beam from a light source such as a semiconductor laser. ) supported by a drive motor (consisting of a rotor and a motor board) to deflect and scan the beam, and use a deflector, drive motor, and means (lens group) to focus the beam onto an object to be scanned (such as a photosensitive drum). etc.), the fixing member (fixing sleeve or fixed shaft) of the hydrodynamic bearing is coupled to the motor board of the drive motor, and this motor board is connected to the motor board of the drive motor. Since it is directly fixed to the storage container, the number of parts is reduced, making it possible to make it smaller and lighter.

[Embodiment] FIG. 1 is a diagram showing a first embodiment of the present invention, and FIG. 2 is a diagram showing details of a thrust bearing portion of this embodiment. In the first embodiment, a rotating polygon mirror 1 is fixed to the upper surface of a flange portion 3 of a rotating shaft 2, which is a movable member of a hydrodynamic bearing, and a drive motor constituting a drive motor is provided at a lower part of the flange portion 3. A rotor G with fixed magnets 4 and FG magnets 5 is fixed (FG is a frequency
An abbreviation for "generator" that generates a pulse signal according to the rotational speed to control the speed. Therefore, the FG magnet is this type of magnet.

), a stator coil 7 constituting a drive motor and a printed circuit board 8 on which an FG pattern is printed are fixedly installed at positions facing each of the driving magnet 4 and the FG magnet 5.

This stator coil 7 is arranged on a printed circuit board 8, and the supply of electricity to the stator coil 7 is controlled by a Hall element (not shown) and a drive circuit and a control circuit formed on the printed circuit board 8, so that the drive motor is activated. Rotation is controlled. A steel plate-shaped yoke 9 is fixed to the printed circuit board 8 so that the magnetic field of the drive magnet 4 effectively acts on the stator coil 7, and the stator coil 7, the printed circuit board 8, and the yoke 9 constitute a motor board 1o. are doing.

On the other hand, the rotating shaft 2 is rotatably fitted with a sleeve 11 that forms a fixed member of the hydrodynamic bearing, and a herringbone-shaped shallow groove 12 for generating dynamic pressure is cut on the outer peripheral surface of the rotating shaft 2. A hydrodynamic radial bearing is constructed. Further, near the opening of the sleeve 11, a spiral shallow groove 13 is carved so that the lubricating fluid flows in the direction of the herringbone-shaped shallow dip 12 (toward the lower end of the sleeve 11).

Further, a thrust plate 14 is arranged at the lower end of the sleeve 11 together with a fixed plate 15, as shown in an enlarged view in FIG.
The thrust plate 14 is provided with a shallow spiral groove 16 on the surface facing the end of the rotating shaft 2 to form a hydrodynamic thrust bearing, and is also provided with holes 17 and 18 for lubricating fluid circulation. It is being Further, the sleeve 11 is provided with an annular recess 19 at a position between the herringbone-shaped shallow groove 12 and the spiral-shaped shallow groove 13 carved on the outer peripheral surface of the rotating shaft 2, and has at least l1 or more grooves. A small diameter hole 20 is provided to ensure the stability of the bearing section using a lubricating fluid.

Here, a one-rotation device is constructed by fixing the sleeve 11, which is a fixing member, to the motor board 10 with adhesive or screws.

The rotating device configured as described above includes a motor board 10
It is installed at a predetermined location by fixing it to the optical box 21 with screws or the like. The optical box 21 includes an imaging lens group 2.
2a, 22b are arranged, and a laser beam L emitted from a light source (not shown) and deflected and scanned by the rotating polygon mirror l on the rotating device is directed to these imaging lens groups 22a, 2.
2b forms an image on the surface of the photosensitive drum 23.

With this configuration, by removing the motor base mlO from the optical box 21, the rotating device can be evaluated or inspected as a single unit in the same building as the conventional example, and furthermore, the rotating device can be easily replaced. be. Furthermore, since the motor case is no longer necessary, the optical box 21, in other words, the deflection scanning device, can be made thinner and smaller, and the weight can be reduced, and the manufacturing cost can also be reduced.

Here, the assembly process of the above rotating device will be described. A fixing plate 15 to which a thrust plate 14 is fixed is fixed to the sleeve 11 by sandwiching a seal member 30 therebetween, and a certain amount of lubricating oil is injected into the bottom of the sleeve 11. At this time, the thrust plate 14
The sleeve 11 is assembled to the motor board 10 after defoaming is performed to remove air bubbles present in the holes 17, grooves 18, etc. provided in the motor board 10.

Thereafter, the rotating shaft 2, on which the rotating polygon mirror 1, rotor 6, etc. are assembled, is fitted into the sleeve 11, thereby completing the assembly of the rotating device. In this way, the above embodiment is easy to assemble and can be even cheaper in cost.

In addition, since the rotating device using a hydrodynamic bearing is extremely small, it is easy to assemble as a deflection scanning device, and the cost of automatic machines is reduced when it comes to automation. Furthermore, the space for automated lines can also be reduced.

Next, a second embodiment shown in FIG. 3 will be described.

In FIG. 3, the same members having the same functions as those shown in FIG. 1 are given the same numbers as in FIG. 1, and the description thereof will be omitted.

In the second embodiment, the sleeve 41 is made of a ferrous metal material or a magnetic material, and is designed to allow the magnetic field of the drive magnet 4 constituting the motor board 10 to act effectively on the stator coil 7. The yoke 39 is integrally formed with the sleeve 41. Since the sleeve 41 is made of the above-mentioned material, at least the inner surface of the sleeve 41 is coated with Ni so that the inner surface of the sleeve 41 forms a hydrodynamic bearing.
It is desirable to perform surface treatment such as , Cr, etc.

Other configurations, functions, etc. are the same as in the first embodiment. In the second embodiment, the printed circuit board 8 and the stator coil 7 are arranged on the yoke 39 that is integrated with the sleeve 41, resulting in a simpler configuration.

FIG. 4 shows a third embodiment of the present invention. In the third embodiment, the sleeve and shaft constituting the hydrodynamic bearing have an opposite relationship to that of the first embodiment, with the former being a movable member and the latter being a movable member. is a fixed member.

In the third embodiment, a polygon mirror 51 is fixed to the upper part of a flange part 53 of a rotating sleeve 52, and a rotor 56 to which a driving magnet 54 and an FG magnet 55 are fixed is fixed to the lower part of the flange part 53. At positions facing each of the driving magnet 54 and the FG magnet 55, there is a printed circuit board 58 on which a stator coil 57, an FG pattern, etc. are printed.
, the magnetic field of the drive magnet 54 is applied to the stator coil 5.
An iron plate-shaped yoke 59 is fixed to the motor board 7 for effective operation, thus forming a motor board 60.

The rotating sleeve 52 is rotatably fitted to a fixed shaft 61, and a shallow groove 62 for generating dynamic pressure is carved on the outer peripheral surface of the shaft 61. A thrust plate 63 is provided at the upper end of the 0-rotating sleeve 52. are arranged and supported in a non-contact manner in the thrust direction. When the lubricating fluid is a gas such as air, the thrust plate 63 has the same shape as that described in the conventional example, and when the lubricating fluid is a noodle body such as oil or grease, it has the shape shown in FIG. It has a similar shape to that shown in FIG. When the lubricating fluid is gas, it is desirable to seal the rotating device by providing a cover 65 with a window 64 for transmitting the laser beam.
A rotating device is formed by fixing by press-fitting, caulking, etc. This rotating device is placed at a predetermined location by fixing the motor board 60 to the optical box 66 with screws or the like.

In the third embodiment, it is easier to assemble the fixed shaft 66 when directly attaching it to the motor board 60, it is easier to assemble it as a deflection scanning device, and it is easier to assemble it automatically (this also reduces costs). It is possible to make it cheaper, and also to make it smaller and lighter.

In addition, since the mounting position of the polygon mirror 51 is not restricted by the presence of the shallow dip 62, the lower end of the fixed shaft 61 is shortened, so there is no need to make a hole in the optical box 66 and install a rotating device. When used for fluids, the sealing performance is very good and deterioration of bearing characteristics is reduced. Furthermore, it is possible to set the mounting position of the polygon mirror 51 downward, which makes it possible to reduce the deflection of the polygon mirror 51 due to vibrations caused by external disturbances, and to improve the image characteristics on the photosensitive drum. .

[Effect of the Invention 1] As explained above, according to the present invention, the fixing member of the hydrodynamic bearing is coupled to the motor board of the drive motor, and the motor board is directly fixed to the storage container, which is an optical box. A motor case or the like is not required, and the deflection scanning device using the hydrodynamic bearing can be made smaller and lighter. Furthermore, since the number of parts can be eliminated, assembly can be automated easily and manufacturing costs can be reduced.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the first embodiment of the present invention, Fig. 2 is a detailed diagram of the thrust bearing shown in Fig. 1, Fig. 3 is a block diagram of the second embodiment of the present invention, and Fig. 4 is a block diagram of the present invention. A block diagram of the third embodiment of the invention, and FIG. 5 is a diagram showing a conventional example.

Claims (1)

[Scope of Claims] 1. Deflecting and scanning the beam by rotating a deflector that deflects the beam from the light source by a drive motor supported by a hydrodynamic bearing, and scanning the deflector, the drive motor, and the beam to be scanned. In a deflection scanning device having a container housing a means for condensing light onto a body, a fixing member of the hydrodynamic bearing is coupled to a motor board of the drive motor, and the motor board is fixed to the container. A deflection scanning device with a built-in dynamic pressure fluid bearing. 2. The deflection scanning device according to claim 1, wherein the fixing member is a fixing sleeve. 3. The deflection scanning device according to claim 1, wherein the fixed member is a fixed shaft. 4. The deflection scanning device according to claim 1, wherein the fixing member and the member constituting the motor board are integrated.