This invention relates to a dynamic fluid bearing rotating apparatus, and particularly to a rotating apparatus for use in a deflection scanning apparatus used, for example, in a laser beam printer or the like.
In recent years, there has been an increasing demand for a rotating apparatus which effects high-speed rotation or highly accurate rotation, and particularly in a laser beam printer or the like, use is made of a dynamic fluid bearing which is rotated in non-contact to provide a highly accurate rotating apparatus. FIG. 1 of the accompanying drawings shows the deflection scanning rotating apparatus of a laser beam printer using a dynamic fluid bearing. A rotary shaft 1 and a sleeve 2 are rotatably fitted to each other, and a thrust plate 3, together with a fixed plate 4, is disposed on the lower end portion of the sleeve 2, and is fixed to an outer cylinder 5. A flange 6 is fixed to the rotary shaft 1, and a rotatable polygon mirror 7 for deflecting a light beam from a light source is fixed to the upper portion of the flange 6, and a yoke 9 having a driving magnet 8 fixed thereto is fixed to the lower portion of the flange 6. A stator 10 fixed to the outer cylinder 5 is disposed at a location opposed to the driving magnet 8. The thrust plate 3 is formed with a shallow groove 11 in the surface thereof opposed to the end portion of the rotary shaft 1, whereby there is formed a dynamic thrust bearing. Also, the outer peripheral surface of the rotary shaft 1 is formed with a herringbone-shaped shallow groove 14 at a location thereon opposed to the inner peripheral surface of the sleeve 2, whereby there is formed a dynamic fluid radial bearing. Further, a spirally shaped shallow groove 15, along which lubricating fluid flows to the dynamic thrust bearing, is formed near the opening portion of the sleeve. Also, a recess 16 and a small hole 17 are provided in the sleeve 2 at a location thereon between the herringbone-shaped shallow groove 14 and the spirally shaped shallow groove 15, thereby securing the stability of the dynamic bearings using liquid (oil, grease or the like) as lubricating fluid.
However, the above-described example of the prior art has suffered from the following disadvantages as a dynamic fluid bearing rotating apparatus:
(1) It has a number of parts and unless the accuracy of each part is made high, it cannot satisfy the characteristic as a rotating apparatus, and this leads to higher working and assembly costs. PA1 (2) It is difficult to make it compact and light in weight as a rotating apparatus because the various parts are coupled together. Particularly where the parts are fastened together by means of screws or the like, the heads of the screws protrude.
The present invention has been made in view of the above-noted problems peculiar to the prior art, and intends to reduce the number of parts of a dynamic fluid bearing rotating apparatus and reduce the manufacturing cost thereof and also makes the apparatus compact and light in weight.
To achieve the above task, according to the present invention, there is provided a dynamic fluid bearing rotating apparatus which has a shaft and a sleeve fitted to each other for rotation relative to each other and in which a dynamic radial bearing is constructed between the outer peripheral surface of said shaft and the inner peripheral surface of said sleeve and one end portion of said shaft is received to thereby construct a dynamic thrust bearing, characterized in that of said sleeve and said shaft, the member on the fixed side is made integral with a fixed member formed of a resin material.
By the sleeve or the shaft being made integral with the fixed member formed of a resin material as described above, the number of parts can be reduced and the manufacturing cost can be reduced and also, the apparatus can be made compact and light in weight.