JPH0429213A - Light deflecting motor - Google Patents

Abstract

PURPOSE:To detect the rotation position of a polygon mirror with a simple constitution by forming a position detecting face part, which is inclined to the rotation axis of a rotor, in a part of reflection faces of a polygon mirror. CONSTITUTION:A position detecting face part 22 inclined to the rotation axis of a rotor 14 is formed in a part of reflection faces 20 of a polygon mirror 19. When the light irradiating the reflection faces 20 of the polygon mirror 19 irradiates the position detecting face part 22 in accordance with rotation of the polygon mirror 19, this light is reflected at an angle to the rotation axis of the rotor 14 differently from the light irradiating the other part of the reflection faces 20, and the reflected light from this position detecting face part 22 is detected to detect the rotation position of the polygon mirror 19. Thus, the rotation position of the polygon mirror is detected with a high precision by the simple constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an optical deflection motor that rotates a polygon mirror integrally with a rotor.

(Prior Art) For example, as shown in FIGS. 7 and 8, an optical deflection motor incorporated in a laser printer or the like is configured such that a rotating shaft is attached to a cylindrical container-shaped bracket 1 in which a stator (not shown) or the like is disposed inside. 2. It is configured to support a rotor 4 consisting of a rotor yoke 3 and the like.

A hexagonal polygon mirror 5, for example, is fixed to the upper end of the rotor 4 so as to be inserted through the rotation shaft 2 and placed on a mirror mount 6.

In this way, the polygon mirror 5 is rotated integrally with the rotor 4, and the laser beam irradiated onto the reflective surface 5a on the side surface of the polygon mirror 5 is reflected to scan the photoreceptor.

In this optical deflection motor, in order to detect the rotational position of the polygon mirror 5, as shown in FIG. A magnetic sensor 10 consisting of a Hall element is mounted on the substrate 9 facing the magnet 8.
A rotation synchronizing signal of one pulse per revolution was obtained from this magnetic sensor 10.

(Problem to be Solved by the Invention) However, in the case where the rotational position of the polygon mirror 5 is detected using the magnet 8 and the magnetic sensor 10 as described above, the rotational position of the polygon mirror 5 can be detected with high accuracy. In order to do this, it is necessary to position the magnetic sensor 10 (boss 7) with high precision and attach it to the rotating shaft 2 so that the magnetic sensor 10 corresponds precisely to a predetermined position of the polygon mirror 5. . For this reason, the assembly work has been extremely troublesome.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an optical deflection motor that can accurately detect the rotational position of a polygon mirror with a simple configuration.

[Structure of the Invention] (Means for Solving the Problems) The optical deflection motor of the present invention has a surface portion for position detection that is inclined with respect to the rotational axis of the rotor formed on a part of the reflective surface of the polygon mirror. It is characterized by its configuration.

(Function) According to the above means, when the light irradiated on the reflective surface of the polygon mirror is irradiated on the surface for position detection as the polygon mirror rotates, the light is different from other parts of the reflective surface. In contrast, the light is reflected in a direction oblique to the rotational axis of the rotor. Therefore, by detecting the reflected light from this surface portion for position detection, it is possible to detect the rotational position of the polygon mirror.

In this case, since the surface portion for position detection is formed on a part of the polygon mirror, the rotational position of the polygon mirror can be detected with high accuracy.Moreover, the rotor has a magnet 1 for position detection. Since there is no need to provide other members such as a gate, a simple configuration can be achieved.

(Example) An example of the present invention will be described below with reference to FIGS. 1 to 4.

3 and 4 show the overall structure of the optical deflection motor according to this embodiment, in which reference numeral 11 denotes a bracket, which is shaped like a cylindrical container with an open top, although not shown. A stator equipped with a stator coil, a bearing device for rotatably supporting a rotating shaft (described later), and the like are disposed inside the stator. Further, below the bracket 11, a board 12 provided with a drive circuit and the like is attached via a connecting member 13. On the other hand, 14 is a rotor, which includes a rotating shaft 15 that is supported by the bearing device and vertically passes through the bracket 11, and a rotor yoke 16 that is fitted and fixed to the rotating shaft 15 and has a rotor magnet (not shown) on its inner peripheral surface. , a mirror mount 17 which is fixed to the rotor yoke 16 and whose upper surface is a horizontal plane perpendicular to the rotation axis 15. The rotor 14 is now rotated about the center of the rotating shaft 15 by energizing the stator coil. Note that a preload boss 18 is fixed to the lower end of the rotating shaft 15.

Now, 19 is a polygon mirror, which in this case has a regular hexagonal shape, as shown in FIGS. 1 and 2.
The six sides of the rotor 14 are mirror-finished, respectively.
The reflecting surface 20 is parallel to the axis of the (rotating shaft 15). A circular hole 19a that fits into the rotating shaft 15 is formed in the center of the polygon mirror 19, and the polygon mirror 19 has its lower surface tightly attached to the mirror mount 17 by inserting the rotating shaft 15 through the circular hole 19a. In this state, it is attached to the rotor 14 by the attachment member 21. In this way, as the rotor 14 rotates, the polygon mirror 19 rotates integrally with the rotor 14.

A surface portion 22 for position detection is formed on this polygon mirror 19. This surface portion 22 is formed by cutting out an end portion of one of the reflective surfaces 20, and as shown in FIG. It is sloping. In this case, among the reflective surfaces 20, the image forming scanning area A where the laser beam is reflected and scanned on the photoreceptor as described later is the central portion of each reflective surface 20, as shown in FIG. , the surface portion 22 for position detection is formed in a portion outside the image forming scanning area A.

The optical deflection motor configured as described above is incorporated into, for example, a laser printer. Inside the laser printer, a semiconductor laser oscillator 23, a lens 24, and a photoreceptor (not shown) are arranged so as to face the reflective surface 20 of the polygon mirror 19.
An optical sensor 25 for position detection is arranged at a position shifted upward by an angle θ from the polygon mirror 19.

Next, the operation of the above configuration will be described.

As shown in FIG. 1, laser light emitted in the horizontal direction from the semiconductor laser oscillator 23 is irradiated onto the reflective surface 20 of the polygon mirror 19, and the reflected light p reflected by the reflective surface 20 passes through the lens 24. The light is incident on the photoreceptor. At this time, as the polygon mirror 19 rotates, the reflection direction (path) of the reflected light p sequentially reflected from the image forming scanning area A of the reflecting surface 20 changes from 91 to Ω in FIG.
Then, the reflected light g is scanned over the photoreceptor.

As the polygon mirror 19 rotates, when only the laser beam is irradiated onto the surface portion 22 for position detection, the reflected light g3 from the surface portion 22 is reflected upward by an angle θ with respect to the horizontal direction. At this time, the optical sensor 25 detects the reflected light Ω3, thereby making it possible to obtain a rotation synchronization signal of one pulse per rotation, which corresponds precisely to the position of the polygon mirror 19.

According to this embodiment, the surface portion 22 for position detection is formed on a part of the polygon mirror 19, and this is used as a means for detecting the rotational position of the polygon mirror 19. Unlike the conventional system in which a magnet 8 is provided, the rotational position of the polygon mirror 19 can be detected with high accuracy without the need for troublesome positioning.

Not only does positioning work become unnecessary, but other members such as the magnet 8 are no longer necessary, and the number of parts can be reduced, so the structure can be simpler than that of the conventional one.

In addition, especially in this embodiment, since the rotational position is detected using laser light from the semiconductor laser oscillator 23 for image formation, there is an advantage that there is no need to provide a separate light source for rotational position detection. That's what you get.

In the above embodiment, the surface portion 22 for position detection is formed at the end of one reflective surface 20, or as shown in FIG. 5 and FIG. A surface portion 2 for position detection is provided at the ridge portion formed by the reflective surface 27.
8 may be formed.

In addition, the present invention can be implemented with appropriate modifications within the scope without departing from the gist, such as being applicable not only to laser printers but also to all devices using optical deflection motors.

[Effects of the Invention] As is clear from the above description, according to the optical deflection motor of the present invention, a part of the reflective surface of the polygon mirror has a surface portion for position detection that is inclined with respect to the rotational axis of the rotor. , it is possible to detect the rotational position of the polygon mirror with a simple configuration, which is an excellent effect.

[Brief explanation of the drawing]

Figures 1 to 4 show an embodiment of the present invention. Figure 1 is a top view of the main part, Figure 2 is a side view of the main part, and Figure 3 is a top view of the optical deflection motor. , FIG. 4 is a side view of the optical deflection motor. 5 and 6 are a top view and a side view, respectively, of a polygon mirror showing another embodiment of the present invention. Moreover, FIGS. 7 and 8 show the conventional example, respectively.
4 and a diagram equivalent to FIG. 4. In the drawings, 14 is a rotor, 15 is a rotating shaft, 19 degrees 26 is a polygon mirror, 20.27 is a reflecting surface, 22.28 is a surface portion, 23 is a semiconductor laser oscillator, and 25 is a photosensor. Applicant: Toshiba Corporation

Claims (1)

[Claims] 1. A rotor equipped with a polygon mirror, characterized in that a part of the reflective surface of the polygon mirror is formed with a surface portion for position detection that is inclined with respect to the rotational axis of the rotor. A motor for optical deflection.