JPS61221721A - Optical deflecting device - Google Patents

Abstract

PURPOSE:To reduce the size of an optical scanning system by forming a mirror, a light source, and a lens system integrally. CONSTITUTION:A collimator lens 16 is screwed fixedly in a screw part provided to a base 15 and a cylindrical beam expander 17 is screwed fixedly in a screw part provided to the collimator lens 16. Further, the base 15 is fixed to a holding cylinder 18 with a screw and the holding cylinder 18 is fixed to an external cylinder case 2' with a screw 19. A laser beam B' projected from a semiconductor laser 12 is made into an elliptically sectioned parallel beam through a collimator lens 16 and then made into a circularly sectioned parallel beam through a cylindrical beam expander 17 to reach a mirror surface 1a. The laser beam deflected by the mirror surface 1a forms an image on a scanned surface through an f.theta lens 4.

Description

[Detailed description of the invention] [Technical field] The present invention relates to a light deflection device.

[Prior Art] Conventionally, information signals have been recorded by deflecting information light modulated by an information signal using a mirror or other deflection means, and scanning the scanning surface on which a photoreceptor is arranged. It is well known to read out information on a scan plane.

Various types of such optical deflection devices have been considered, and a rotating polygon mirror type optical deflection device is one of them. This rotating polygon mirror type optical deflector has a high deflection speed and can perform continuous optical deflection, so it is possible to record or read information at high speed and with high density.

FIG. 1 is a sectional view of a scanning optical system using a conventional rotating polygon mirror type optical deflector.

In Figure 1, 1 is a rotating polygon mirror, 2 is an outer case of the optical deflection device, 3 is an entrance window glass, 4 is an f/θ lens for imaging, 9 is a beam expander, and 10 is an optical modulator. , 11
is a He-Ne laser. The entrance window glass 3 is attached to the outer case 2 by a window glass holder 5 which is fixed to the outer case 2 by screws 6, and the f/θ lens 4 is attached to the lens adapter 7 which is fixed to the outer case 2 by screws 8. A screw-in is attached to the. The outer cylindrical case 2 shields the rotary polygon mirror 1 from outside air in order to prevent the mirror surface of the rotary polygon mirror 1 from being contaminated by dust, oil, etc. in the air.

The laser beam B emitted from the He-Ne laser 11 is modulated by the optical modulator 10 according to recorded information, etc., is expanded by the beam expander 9, passes through the entrance window glass 3, and is rotated by the rotating polygon mirror 1. (The oriented laser beam is f
- An image is formed on the scanned surface (not shown) by the θ lens 4.

Conventionally, when recording or reading information using an optical deflection device, it was common to use a gas laser such as He-Ne as a light source as shown in Figure 1, but gas lasers are large and , which has the drawback of requiring a large amount of space within the system.

Furthermore, in such devices, optical adjustment has been performed for each unit separately, or after each unit has been mounted on the system board. For this reason, optical adjustment was difficult and required a great deal of time.

[Purpose] The present invention has been made in view of the above points, and its purpose is to provide an optical deflection device that can be miniaturized and can perform optical adjustment easily and in a short time. .

[Example] Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a plan sectional view of the optical deflection device of this embodiment, and FIG. 3 is an Ax sectional view of FIG. 2.

This embodiment will be explained according to the drawings.

In FIGS. 2 and 3, the same numbers as in FIG. 1 indicate the same members as in FIG. 1.

In FIGS. 2 and 3, 12 is a semiconductor laser, 16 is a collimator lens, 17 is a cylindrical beam expander, and 13 is a heat radiation fin fixed to the base 15 of the semiconductor laser 12 with screws 14. The collimator lens 16 is screwed and fixed to a threaded portion provided on the base 15, and the cylindrical beam expander 17 is screwed and fixed to a threaded portion provided on the collimator lens 16. Further, the base 15 is fixed to the holding cylinder 18 with screws (not shown), and the holding cylinder 18 is fixed to the outer cylinder case 2' with screws 19.

Generally, a laser beam emitted from a semiconductor laser is a divergent beam with different divergence angles in two orthogonal directions, and it is necessary to convert it into a parallel beam. The collimator lens 16 is for this purpose. Furthermore, since the cross-sectional shape of the parallelized beam is elliptical, it can be used as a cylindrical beam or as needed.
When the expander 17 is installed after the collimator lens 16, it is necessary to make the cross-sectional shape circular. Furthermore, since the performance of a semiconductor laser changes depending on temperature changes, it is necessary to keep the temperature constant at all times, and in particular, it is necessary to keep the temperature low in order to prolong its life. For this reason, the laser chip of the semiconductor laser (
It is necessary to place a heat pump such as a Bertier element near the laser chip (not shown) to cool the laser chip and release the removed heat to the outside. The heat dissipation fan 13 is a member for dissipating the heat.

Now, as mentioned above, the laser beam emitted from the semiconductor laser 12 becomes a parallel beam with an elliptical cross section by the collimator lens 16,
7, it becomes a parallel beam with a circular cross section and reaches the mirror surface 1a.

The laser beam deflected by the mirror surface 1a forms an image on a scanned surface (not shown) by an f.theta. lens 4, similar to the conventional example shown in FIG.

In FIG. 3, 20 is a substrate for mounting and fixing the optical deflection device with screws 21, and 22 is a rotating shaft to which a polygon mirror is attached.

FIG. 4 is a partial sectional view of a second embodiment of the optical deflection device in which the semiconductor laser 12 is movable in a direction perpendicular to the optical axis of the collimator lens 16.

In the optical deflection device shown in FIGS. 2 and 3, the emission part of the laser chip 23 (shown in FIG. 4) of the semiconductor laser 12 must be placed precisely at the focal point of the collimator lens 16. If the emission part of the laser chip 23 is deviated from the focal point of the collimator lens, the direction of the beam after exiting the collimator lens 16 may be tilted, or the imaged spot may become blurred on the scanned surface.

In FIG. 4, a lens mounting plate 26 is provided between the base 15' and the collimator lens 16', and the collimator lens 16' is screwed into this lens mounting plate 26.

Collimator lens 16' at the output part of the laser chip '23
The position adjustment in the direction perpendicular to the optical axis with respect to the optical axis is performed by shifting the base 15' with respect to the lens mounting plate 26 within the range of ΔY by the play of the insertion hole of the screw 27'. Furthermore, the position adjustment in the optical axis direction is performed by adjusting the amount by which the collimator lens 16' is screwed into the lens mounting plate 26.

In Fig. 4, 25 is the laser cap of the semiconductor laser, 2
4 is a laser emission window glass.

FIG. 5 is a partial cross-sectional view of a third embodiment of the present invention, in which the incident beam is tilted by a small angle φ with respect to the plane formed when a straight line perpendicular to the mirror surface rotates around the rotation axis. It is something that For example, when scanning a light beam with a rotating polygon mirror, 8
In the case of a rotating polygon mirror, the beam that is reflected and scattered on the scanned surface is reflected again on the mirror surface next to the mirror that is deflecting the beam and reaches the scanned surface, creating a ghost image at a fixed point on the scanned surface. .

Figure 5 shows the mounting surface 18 on the outer cylinder case 2' side of the holding cylinder 18'.
The formation of a ghost image is prevented by tilting the mounting surface 18-b on the base 15 side by φ with respect to -a.

The present invention described above has the following advantages.

First, since the mirror, light source, and lens system are integrated, the scanning optical system can be downsized, and the system using the optical deflector can be made compact. Further, by integrating the optical system, the cost of the scanning optical system can be reduced because the members for attaching and holding the light source lens system and part of the dustproof window glass, which were conventionally available, can be omitted.

Furthermore, the integration of the mirror, light source, and lens system means that optical adjustments that were conventionally performed for each unit separately or after each unit was mounted on the system board can now be performed using the optical deflection device. To make it possible to complete optical adjustment easily and in a short time by making it possible to complete it comprehensively in a computer.

In addition, since the output surface of the semiconductor laser, collimator lens, and cylindrical beam expander can be housed inside the sealed case of the optical deflection device, it is possible to prevent dust from adhering to the glass or lens surface and causing a loss of light intensity. It is something that can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a scanning optical system using a conventional optical deflection device, Fig. 2 is a plan sectional view of the optical deflection device of this embodiment, Fig. 3 is a sectional view at A in Fig. 2, and Fig. 4 The figure is a partial sectional view of the second embodiment, and FIG. 5 is a partial sectional view of the third embodiment. In the figure, 1 is a rotating polygon mirror, 4 is an f/θ lens, and 12
16 represents a semiconductor laser, 16 represents a collimator lens, and 17 represents a cylindrical beam expander.

Claims (1)

[Scope of Claims] A light beam generating means for emitting a light beam, a deflecting means for deflecting the light beam emitted from the light beam generating means to scan a surface to be scanned, and a first device including the deflecting means. a case member; a second case member to which the light beam generating means is attached; an attachment means for attaching the second case member to the first case member; and a second case member for attaching the second case member to the first case member; 1. An optical deflection device comprising: an adjusting means for adjusting the mounting position of the second case member.