JPS6026432A - Motor unit - Google Patents

Abstract

PURPOSE:To prevent a motor unit from damaging during its transportation by braking one end of a shaft of a motor which uses dynamic fluid pressure bearings by a tension of a spring during the stoppage of its operation and releasing the brake against the tension of the spring by the dynamic pressure of the fluid. CONSTITUTION:A rotary sleeve 7, on which a polygonal mirror 2 is mounted, is rotatably engaged with a stationary shaft 6, and driven by a motor mechanism, not shown, provided under the sleeve 7. An elastic member 18c at the end of a retainer 18 is contacted with a thrust retainer 8 provided at the top of the sleeve 7 to brake the sleeve 7. When the sleeve 7 starts rotating, its rotation is transmitted from the member 18c to the retainer 18, the recess 18b of the retainer 18 is removed from the slot 16a of a stationary member 16, and the retainer 18 is separated by a spring 19. Then, the sleeve is smoothly rotated at a high speed by a dynamic fluid pressure bearing mechanism. Thus, the brake by a thrust is automatically removed, thereby preventing it from damaging during its transportation and due to mistake in its operation. This is adapted for an LBP of a computer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motor unit using a dynamic pressure bearing mechanism.

With the development of computer graphics represented by CAD/CAM, which has been put into practical use in recent years, there is a strong demand for Gonviewer output models with higher resolution, faster printout, and noise-free printing. ing.

Against this background, recently, laser beam printers (hereinafter abbreviated as LBPs) have become increasingly popular and demand is increasing. LBP is basically an application of an electrophotographic process, and its configuration is as shown in Figure 1. The laser emitted from the laser unit 1 is turned into fixed light by a polygon mirror rotationally driven by a motor 3, and an image is formed on a photosensitive drum 5 by a lens system DA. When scanning the laser beam, the laser is lI! The latent image is modulated by a laser drive circuit (not shown) according to the II image, and a latent image is formed on the photosensitive drum S. The latent image drawn on the photosensitive drum S is transferred onto recording paper through a development and transfer process, and is further fixed to complete the copy.

LBP based on the above principle has high resolution and good image quality, can be operated at considerably higher speeds than general printers, is non-impact, has a low noise level, and satisfies the above conditions.

Now, what occupies an important position in the mechanism of this LBP is the polygon mirror unit driven by the motor 3, and its laser scanning performance is connected to the quality of the image. For example, uneven rotation of the motor 3 appears as a fluctuation in the line in the paper feeding direction, and whirling of the polygon mirror causes the density of the scanning line in the paper feeding direction to appear as density unevenness in the image.

In order to maintain such a high level of noise, and to reduce the noise level of motors that are inevitably required to operate at higher speeds due to higher scanning speeds, there are many difficulties with ball bearings. There are also ways to support rotation.

As for the configuration of a hydrodynamic bearing, as in the first factor, the above.

Middle, lower case qa,? b. In the sealed casing 9C, the rotating sleeve 7 is fitted into the fixed shaft B press-fitted into the lower case 9C with a gap of 3 to IO μm in the radial direction, and the outer peripheral surface of the fixed shaft A spiral groove or a herringbone groove is formed on the inner peripheral surface of the rotating sleeve 7 to constitute a known air bearing, and the action of the magnet 10 fixed to the rotating sleeve 7 and the magnetic pole// fixed to the middle case 9b. When the rotating sleeve 7 rotates, fluid pressure is generated in the thrust bearing which is press-fitted into the end of the 5-turn sleeve 7 and can come into contact with the fixed shaft A9.

Due to the shibori ga provided on the thrust receiver g, the thrust receiver g1 rotates, the polygon mirror 2 fixed thereto, the M amount of the rotating body such as the magnet IO, etc. are balanced and floated, and during rotation, the fixed shaft 6 and the thrust receiver g However, when the 5-turn sleeve 7 starts or stops, the fixed shaft 6 and the thrust bearing g come into contact when the number of revolutions falls below the floating rotation speed.

However, in this method, only a rotating sleeve is inserted into the fixed +11+ A, and one rotation sleeve 7
has no constraints in the axial direction. Therefore, the storage/rotation sleeve 7 for transporting this unit or a device incorporating this unit vibrates greatly in the axial direction, causing repeated collisions between the fixed shaft 6 and the thrust bearing g.

■ Due to the collision between the fixed shaft and the thrust bearing! 7. The position of the thrust receiver t is shifted.

@ The collision between the shaft 6 and the thrust receiver g deforms the sys-thrust receiver g, and the position where the thrust receiver g and the fixed shaft 6 come into contact shifts from the center of rotation. This leads to an increase in starting torque and amount of wear.

■ If the contact point of the thrust plate and the center of rotation are misaligned, the amount of levitation may decrease, and in extreme cases, it may not be possible to levitate completely.
The amount of wear may increase significantly.

- Due to the collision between the shaft 6 and the thrust bearing, the extra thrust bearing wears out and generates abrasion powder.

Particularly in the case of the above-mentioned alignments @, ■, and ■, the generated abrasion powder enters the extremely small gap between the bearings and causes the air bearing to seize, making the motor unable to rotate.

In order to eliminate such alignment, there have been conventional examples as shown in FIGS. 3 and 3. In other words, when transporting, as shown in Figure 3, the upper case? A hole 12 is provided in the center of the bottle with a flexible part attached to the bottle-shaped head. The presser member 13 equipped with e is inserted into the hole/
Insert the head into 2 on the inside, and insert the O-ring near the head of presser member/3. d, an O-ring groove is provided in the main body of the presser member /3, and a pair of parallel grooves /3a, /3b are provided in the upper part of the main body, and the feeding gap is the upper parallel groove /3alC. % Insert the seat plate /y, which has a notch that fits into the parallel grooves /3a and /3b, into the upper parallel groove lj&, fit the hole at one end of the seat plate /g into the protrusion 9dK of the upper case 9a, and insert the small The other end of the seat plate /lI was screwed with a screw 15 so that the head of the pressing member /3 was in contact with the thrust receiver tVc. When using the device, tighten the small screws as shown in the diagram.
After loosening and refitting the seat plate/4t into the parallel groove/3b,
Screw the small screw 15 into the upper case 9a. At this time, the 0-ring/3d maintains airtightness between the head of the holding member/3 and the upper case qa, and the 0-ring/3c maintains airtightness between the holding member/3 and the upper case qa in both Figs. 3 and 7. keep.

However, such a system has a complicated structure, and if the user forgets to release the presser member 3 when installing the device, there is a risk that the motor will not rotate and the motor drive circuit will be destroyed.

An object of the present invention is to eliminate the above-mentioned drawbacks by adopting a configuration in which the pressing member is released by starting rotation of the motor.

The present invention provides a motor unit using a hydrodynamic bearing.
The device is equipped with a holding member that constantly holds down the rotating part of the motor until the motor is used, and separates from the rotating part of the motor when the motor rotates when the motor is started to be used.

Embodiments of the present invention will be described below with reference to the drawings.

Figure 5% Figures 6 and 7 show embodiments of the present invention;
7 are longitudinal sectional views of the upper part of the motor 3, and FIG. 6 is a plan view of the holding member. Two fixing members/6 are fixed to the lower surface of the upper case 9a symmetrically about the center of the upper case qa. The fixing member /6 is cylindrical and has an annular groove /Aa slightly above the center part, and the lowermost surface of the stopper plate /7 is located on the outer periphery of the disc of the stop plate /7, with the lowest part of the hollow cylinder extending into the disc. The top surface is fixed. The holding member/g is shaped like a bottle with a head, and has two arms/ga that are symmetrical about the center from the head, and the tips of the arms/ga are hollow and semi-cylindrical. It has a semi-cylindrical recess /fb.

The bottle part of the holding member /g is fitted into the cylindrical hole /a of the stop plate /ri, and there is a space between the stop plate /g and the holding member igO along the outer circumferential surface of the hollow cylindrical part of the stop plate /7. A compression spring /q is provided. When the assembly of this motor unit is completed, the four parts 1gb of the holding member /g are kept locked in the groove /Aa of the fixing member /6. This state is shown in FIG. When shipped in this state, the rotating sleeve 7
Since the thrust receiver t of the rotor is pressed appropriately, the vibration shock S of the rotating sleeve does not occur.

When the rotating sleeve starts rotating when the device is started to be used, the presser member/1 is rotated (b) due to the friction between the thrust receiver g and the elastic member/gc at the tip of the presser member/1. counterclockwise), fixing member/A groove/A
Since the presser member/g's recess/gb is disengaged from a,
Due to the biasing force of the compression spring /q, the presser member l is lifted upward, and the presser member /g and the thrust receiver are separated from each other as shown in FIG.

The elastic member /fc at the tip of the holding member /g is preferably made of soft rubber or the like in view of increasing the frictional force with the thrust receiver and making the holding force elastic during transportation.

In this method, not only can the thrust presser be automatically released without opening or closing the cover of the device, but also the release of the presser member is done at the same time as the device starts to be used, so the thrust presser can be released. There is no longer any fear of forgetting to do so and damaging the motor drive circuit.

Furthermore, this configuration does not require any external operation, as the thrust presser mechanism is housed inside the motor case.
It can also be said that it is very effective against the case compatibility, which is a problem with hydrodynamic bearings.

FIG. 5% FIG. 6 is a longitudinal sectional view showing another embodiment of the present invention. The center of the upper case q& of the motor unit is a boss, and a cylindrical hole 20a is provided through the boss. The holding member 20 is cylindrical and has a flange in the middle.
Il1ii b.

An O-ring 20C is provided in the upper circumferential groove to maintain airtightness between the holding member: LO and the upper case 9a.

The upper part is provided with a recess 20e for locking a plurality of balls 20d arranged at equal intervals, which are fitted into the cylindrical hole λθaK and guided in the vicinity of the O-ring λOC. In addition, the elastic member 2/ is provided with a small screw 15 on the top surface of the upper case 9a.
The flange part is made a solid hole, and the inner peripheral surface of the hollow cylindrical shape of the flange part is along the outer periphery of the presser member O, and the ball 20d is wrapped around the ball 20d at a position opposite to the recess θe provided in the presser member 20 at the upper end. It has a shape like that. The support member 2 is a hollow cylinder whose upper flange portion is fixed to the upper case 9a with small screws 15 on the lower center surface of the upper case 9a, and has a round hole in the center of the bottom surface into which the presser member 2Q is inserted. A compression spring λ3 is provided between the lower surface of the flange 20b of the holding member 20 and the upper surface of the bottom surface of the supporting member.

During transportation, the ball socket Od and the recess 20e are engaged with each other as shown in FIG. 3, resisting the biasing force of the compression spring 23 and pressing the thrust receiver g. On the other hand, when the rotating sleeve 7 starts rotating during use, the thrust receiving member and the holding member: lO
The holding member 20 rotates due to the friction, and the engagement between the ball 20d and the recess 1Oe is disengaged, and the holding member 20 is released by the biasing force of the compression spring 3 as shown in FIG. This configuration has the advantage that the presser member can be released regardless of the rotational direction of the motor.

1.1 and 1.1 are longitudinal sectional views showing still other embodiments of the present invention, and FIG. 10 is a plan view of the central portion of FIG. 11. The presser member JF is a resin molded product having a cylindrical shape and a centrally symmetrical elastic member which is provided diagonally downward and has two arms b that press the upper glaze case qa. O to maintain airtightness with the upper case 9a in the annular groove
Equipped with ring col a. The holding member is fitted into a hole in the center of the upper case 9a and guided. Further, the support member 25 is hollow cylindrical and has a flange at the bottom, and has an upper bottom surface. It is fixed to the top surface of the center part of a, and there are two notches 5 centrally symmetrical to the top bottom surface.
A round hole 25a having a diameter b is provided. The size of the notch 5b is such that the holding member, the arm of 21I, and the base of 2Fb can pass through, and the round hole 5a is large enough to allow the holding member, the arm of 21I, and the base of 2Fb to pass through.
The cylindrical part of the arm 2b can pass through, but the arm 2b cannot pass through.

This structure is very simple compared to the previous embodiment, since the presser member 2 and the arm body b, which is the ammunition part, are integrated. When the holding member 27 is transported, the base of the arm 211b is caught in the circular hole of the supporting member S, so that it is in the state shown in FIG. 11 in which it presses the thrust receiver g. When the device is in use, the F presser member 2'l rotates due to the frictional force between the thrust receiver g and the presser member body, and the arm col llb of the presser member: llI and the notch 25b of the support member ko 5 are aligned, and the presser member -
Due to the elasticity of the arm 24th, the holding member 2g can be separated from the thrust receiver g.

In the above example, the holding member has been explained to hold down the thrust receiver during transportation, but it is not necessarily limited to this, and it is also possible to hold down a rotating sleeve or a polygon mirror, for example.

As explained above, one aspect of the present invention is that in a motor unit using a hydrodynamic bearing, the thrust receiver is released from the press at the same time as the rotation of the 5-turn sleeve starts, so there is no need to remove the cover of the device, and the outside air is Since it is possible to automatically release the suppression of the rotating body without entering the equipment and causing trouble, it has the effect of preventing damage to the motor drive circuit caused by forgetting to release the suppression.

[Brief explanation of the drawing]

Fig. 1 is a principle diagram showing an overview of LBP, Figs. , FIG. /Figure, 1st
- The figures show still other embodiments, in which Figures 1/ and 1 are longitudinal cross-sectional views, and Figure 1O is a plan view of the central part of Figure 11 and 1. C... Polygon mirror 3... Motor 6... Fixed shaft R... (B) Rolling sleeve g... Thrust receiver qa... Upper case /3. /g', :10,21
1... Pressing member /6... Fixing member /9,23.
・・Compression spring / ・・Elastic member: 12, . 2g...
・Supporting member. Patent Applicant: Canon Co., Ltd. Agent: Parti Arai

Claims (1)

[Claims] l In a motor unit using a hydrodynamic bearing, a holding member is provided which has a locking part that comes into contact with the rotating part of the motor and engages with a locking part on the upper case side, and the holding member is attached to the upper case of the motor. It has a locking part that separates from the locking part of the presser member when the guide part and the presser member rotate. A motor unit comprising an elastic member ψ1a that biases the holding member in a direction away from the rotating part of the Tanabata when the member is released from the locking part of the upper case.