JPH05683B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to information recording devices such as laser printers, scanners such as copying machines, and videos, and particularly to a rotary drive device suitable for use therein.

A polygon mirror is attached to the rotating side of a high-speed motor used as a scanner in a laser beam printer, a copying machine, etc., and a signal-modulated laser beam is projected and deflected onto this polygon mirror, thereby producing a traveling photosensitive material having a photoconductive layer, for example. A system has already been proposed in which a latent image is formed by scanning the body, and a copy is made of the latent image using a known electrophotographic method.

In such scanners, it is already known to use a surface facing type motor using a flat armature coil and a permanent magnet as a means to make the scanner as small as possible.

FIG. 1 is a schematic perspective view showing a scanner of a laser beam printer using such a flat type motor with a polygon mirror attached as a rotational drive device.
The signal-modulated laser beam projected from the polygon mirror PM is rotated at high speed by the motor M.
The photoconductive layer of the photoreceptor D is deflected by the mirror surface of the photoreceptor D and is swung to scan the photoconductive layer running through the lens system L, thereby forming a latent image.

An example of a flat motor used in the above scanner will be explained with reference to FIG.

In FIG. 2, a shaft 4 is rotatably attached to bearings 3, 3 disposed on the housing member 1 and the cover member 2, respectively, and a rotor receiving member 5 is fixed at an intermediate position of this shaft. . A disk 6 is fixed to the rotor receiving member 5, and an annular magnet 7 magnetized in the circumferential direction is attached to this disk to form a rotor. A predetermined number of armature coils 9 are disposed on the inner bottom of the housing 1, facing the magnets 7, via a printed board 10, forming a stator.

One end of the shaft 4 passes through the cover member 2 and projects outward, and a polygon mirror 8 is fixed to the projecting portion.

In the figure, reference numeral 11 denotes a Hall element disposed opposite to a magnet as a tact sensor used for switching the phase of the armature coil and checking the rotation speed, and is mounted on the printed board 10 to constitute a DC Hall motor. Reference numeral 12 denotes a spring arranged as a pressure biasing means for maintaining the stability and rigidity of the bearing.

Although the one shown in the second figure is shown as using a pole bearing, it is possible to use a fluid dynamic pressure bearing in order to obtain higher rotational stability, lateral fall accuracy, and low rotational unevenness. This should be easy to understand.

The flat motor described above is of course effective in making information processing equipment more compact as a whole, but there is an extremely strong demand for smaller size and lower cost for this type of equipment. In response to this, the present invention integrates the rotor of the motor and the polygon mirror in a rotary drive device using a flat motor and a polygon mirror as described above, thereby making the device itself smaller and having a structure with fewer parts. This provides a simple rotary drive device.

FIG. 3 shows an embodiment of the invention.

The one shown in the same figure is similar to the one shown in the second figure above in that it uses a surface-facing flat motor, so corresponding parts are given the same reference numerals, and the following description of the configuration will also be based on the differences. I will mainly explain a certain part. In the rotational drive device shown in FIG. 3, a shaft 4 supported by bearings 3, 3 has a flange portion 4a formed at an intermediate portion thereof, and a magnet 8a serving as a rotor is mounted and fixed on this flange portion 4a. The outer periphery of this magnet 8a is formed into a polygonal shape, and each of its surfaces is mirror-finished to reflect the laser beam, so that it functions as a rotor of a drive motor and at the same time functions as a rotating polygon mirror. It turns out.

The above-mentioned magnet that also serves as a polygon mirror is made by forming a magnetic material such as barium ferrite or alnico into a polygonal shape, and then applying copper plating or electroless nickel plating to a thickness of 30 to 100 mm depending on the wavelength of the laser on a base coated with copper or the like. It is obtained by applying it to a micron thickness, obtaining a desired mirror surface by precision cutting and polishing, and then magnetizing it.

In addition, by using a solid solution type magnetic material that can be machined and milled, such as manganese-aluminum alloy, and forming it into a polygonal shape, and then polishing and magnetizing it, high rotational strength, good workability, A product with high processing accuracy can be obtained.

FIG. 4 shows an embodiment in which the rotating part of the rotary drive device according to the present invention is supported by a hydrodynamic bearing, and in its basic configuration, the parts corresponding to those shown in FIG. Since the same reference numerals are used, the structure can be easily understood.

In this embodiment, a bearing sleeve 13 extending below the housing member 1 is fixed,
An extension of the shaft 4 supporting the polygon mirror rotor 8a is loosely fitted into the sleeve 13 with a gap of approximately several microns, and a spiral shape is formed around the outer periphery of the extension of the shaft 4. A large number of herringbone-shaped grooves are formed to form a hydrodynamic bearing.

As explained above, the present invention provides an information recording device,
In particular, in the rotary drive device, since the motor rotor and the polygon mirror for optical information scanning are integrated, the axial length of the entire device can be reduced, and the number of parts can be reduced, making processing and processing easier.
It is possible to obtain high-quality images by reducing mirror blur caused by assembly errors and blurring of signal light scanning.
For example, as shown in FIG. 3, a polygon mirror (roller) 8a which is the main inertial body in the rotating part
can be placed between the two bearing parts, which is extremely effective in obtaining good rotational motion with little vibration.

Of course, this is true not only when using a ball bearing link but also when using a hydrodynamic bearing, and when a bearing part is present at one end of the shaft as shown in Figure 4. However, the length of the portion outside the bearing portion is small, and a remarkable effect can be achieved compared to the case where a hydrodynamic bearing is applied to a known type as shown in FIG. 2, for example.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing a scanner of a laser beam printer, FIG. 2 is a sectional view of a rotary drive device used in the devices shown in FIG. 4 is a sectional view of a rotary drive device showing another embodiment of the present invention. 1...Housing member, 2...Cover member, 3
... Bearing, 4 ... Shaft, 7 ... Magnet, 8 ... Polygon mirror, 8a ... Polygon mirror and rotor, 9
...Armature coil, 13...Sleeve.

Claims (1)

[Claims] 1. In a flat motor in which a flat armature coil and a magnet rotor are arranged facing each other,
An information recording device in which the outer peripheral surface of the magnet rotor is formed into a mirror surface.