JPH0486616A - Multiple reflection type ray scanner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a light beam scanning device for scanning a light beam back and forth.

Conventional technology laser beam printer, engraving type laser marker device,
BACKGROUND OF THE INVENTION Light beam scanning devices are used in facsimiles, barcode readers, optical card readers, laser microscopes, laser micros, optical switches, optical exchangers, and the like. As such a beam scanning device, a galvano mirror scanner or a polygon mirror scanner is used. However, in galvano mirror scanners, the drive system for the mirror is a moving magnet or moving coil with a large mass, which not only consumes a lot of power and makes high-speed scanning difficult, but also requires a detection system to detect the actual rotation angle of the mirror. It had the disadvantage of being large when including the above.

In addition, since a polygon mirror scanner is a polygon mirror that rotates at a constant speed, when the light beam deflected by the scanner is scanned directly onto the scanning surface through the objective lens, the light beam becomes f-sin θ・dθ/dt on the scanning surface. It is scanned at a speed expressed as , and uniform speed scanning cannot be obtained. For this reason,
Since the recording method required for laser printers is based on uniform linear scanning of the laser beam, the above scanning speed f-sin θ・dθ/dt can be expressed as f・θ・dθ/d.
A special f-theta lens system had to be used to convert to t.

In contrast to the above, a movable mirror that is rotatably provided around the − axis, a reciprocating drive device that rotates the movable mirror back and forth, and a reciprocating drive device that is provided in a fixed position opposite to the movable mirror and is connected between the movable mirror and the movable mirror. A multiple reflection type beam scanning device has been proposed which is equipped with a fixed mirror for multiple reflection and rotates the movable mirror back and forth to change the deflection angle of the reflected light and scan the reflected light back and forth. According to this, multiple reflections between the movable mirror and the fixed mirror allow the light beam to be deflected at a larger deflection angle than the rotation angle of the movable mirror, resulting in a smaller drive system and lower power consumption. A drive device such as a multilayer piezoelectric actuator capable of high-speed operation can be used, and the movable mirror can be rotated with fθ characteristics by voltage control or injection charge control, and the fθ lens system can be removed.

Problems to be Solved by the Invention However, in the above-mentioned conventional beam scanning device, when the movable mirror is rotated back and forth at high speed, deflection vibrations of the movable mirror occur, making it impossible to scan at a constant speed.

The present invention has been made against the background of the above circumstances,
The purpose is to provide a multiple reflection type light beam scanning device that can scan light beams at high speed and at a constant speed.

Means for Solving the Problems The gist of the present invention for achieving the object is to provide a movable mirror rotatably provided around a -axis, a reciprocating drive device for reciprocating the movable mirror, A fixed mirror is provided in a fixed position opposite to the movable mirror for multiple reflections between the movable mirror and the movable mirror is rotated back and forth to change the deflection angle of the reflected light and perform reciprocating scanning. In the multi-reflection type optical beam scanning device of the type, a vibration damping member is provided which contacts the movable mirror at the end of the reciprocating stroke of the movable mirror, so as to suppress the flexural vibration that occurs when the movable mirror changes the reciprocating direction. It's because I did it.

Operation and Effect of the Invention With this arrangement, the movable mirror is brought into contact with the vibration damping member at the end of its reciprocating stroke, so that the deflection vibration that occurs when the movable mirror switches in the reciprocating direction is suppressed by the vibration damping member. It can be attenuated early.

Embodiment In FIG. 1, a fixed mirror 14 is attached to a beam 12 whose both ends are fixed to a frame (not shown). Further, a rotating shaft 16 extending in an axial direction parallel to a line perpendicular to the beam 12 is rotatably supported by a bearing (not shown). The rotary shaft 16 has a mounting surface 18 formed by cutting out a longitudinally intermediate portion thereof, and a movable mirror 20 is fixed to the mounting surface 18. Thereby, the movable mirror 20 is disposed facing the fixed mirror 14.

A pair of rod-shaped laminated piezoelectric actuators 22 and 24 are each fixed between the rotating shaft 16 and a frame (not shown). Those laminated piezoelectric actuators 2
2.24 is proportional to the amount of injected charge supplied via those lead wires 22L, 24L in the longitudinal direction (stacking direction)
The rotary shaft 16 is driven to reciprocate around the shaft at high speed by the laminated piezoelectric actuators 22 and 24. In this embodiment, the laminated piezoelectric actuators 22 and 24 function as a reciprocating device for the movable mirror 20.

As shown in detail in FIG. 2, the rod-like structure has upper and lower ends fixed by fixing brackets (not shown) so that the movable mirror 20 comes into contact with the end of the movable mirror 20 when it reaches the end of its reciprocating rotation stroke. Vibration damping member 26.28.30.
32 is provided in a direction parallel to the rotating shaft 16. The damping members 26, 28, 30, and 32 are made of a so-called damping alloy that has a high property of absorbing vibration energy.

The movable mirror 20 has its both ends enlarged more than the fixed mirror 14, and the optical path of the multiple reflections of the laser beam performed by the movable mirror 20 and the fixed mirror 14 is controlled by vibration damping members 26, 28, .
30.32 so that it will not be affected.

In the multiple reflection type beam scanning device configured as described above, as shown in FIG.
2.24, when the amount of charge injected via the lead wires 22L, 24L is changed periodically, the movable mirror 20 is rotated back and forth by the laminated piezoelectric actuator 22.24, which expands and contracts accordingly. As a result, the movable mirror 20
The laser beam L in incident on the movable mirror 20 is deflected by an angle several times larger than the rotation angle to produce an output laser beam. It is emitted from the movable mirror 20 as u, and is periodically scanned within the range of the deflection angle 2θ. That is, when the movable mirror 20 is parallel to the fixed mirror 14, multiple reflections shown in the plan view of FIG. 4 and the side view of FIG. 5 occur between the movable mirror 20 and the fixed mirror 14, and As shown in , the output laser light is output when the deflection angle is zero.

ut is emitted.

When the movable mirror 20 is rotated counterclockwise in the plan view, multiple reflections shown in the plan view of FIG. 6 and the side view of FIG. 7 occur between the movable mirror 20 and the fixed mirror 14. 6
As shown in the figure, the output laser beam is output when the deflection angle is +θ. U is emitted. On the other hand, when the movable mirror 20 is rotated clockwise in the plan view, the multiple reflections shown in the plan view in FIG.
As shown in FIG. 8, the output laser beam is output with a deflection angle of -θ. ut is emitted. Each time the laser beam is reflected by the movable mirror 20, it is deflected by an angle twice the rotation angle of the movable mirror 2o, and as a result, it is emitted at a large deflection angle. The movable mirror 20 of this embodiment is -1,5
As a result of the reciprocating rotational drive within the range of 1.5° to +1.5°, the output laser beam L out is deflected within the range of -30' to +30°.

In the above-mentioned multiple reflection type beam scanning device, since the movable mirror 20 only needs to be rotated at a small angle, it is possible to use the laminated piezoelectric actuators 22 and 24, which are small in size, have low power consumption, and can operate at high speed. Type piezoelectric actuator 2
2.24 can be driven with fθ characteristics, so f
This has the advantage of not requiring a θ lens.

And output laser light. When driving the laminated piezoelectric actuators 22 and 24 at a high frequency to scan ut at high speed, the shape shown in FIG. 10 is the shape shown in FIG. As shown, it is unavoidable that the movable mirror 20 generates bending vibration, which is the output laser beam. Uniform velocity scanning of uL was inhibited.

In contrast, in this embodiment, as shown in FIG. 2, when the movable mirror 20 reaches the end of its reciprocating rotation stroke, the rod-shaped vibration damping member 26. 2
8.30.32 is provided, the bending vibration of the movable mirror 20 is absorbed while the end of the movable mirror 20 is in contact with the vibration damping member 26.32 or 28.30. This eliminates the problem that uniform velocity scanning is inhibited due to the deflection vibration of 20.

Here, as shown in FIG. 3, during the period when the movable mirror 20 is located at the end of its reciprocating stroke, the linearity of deflection is impaired, so the scanning area excluding that period is used. For example, when applied to a laser printer, printing is performed in its scanning area. In this case, since printing is performed by reciprocating scanning, one optical sensor is required at each end, but printing may be performed by one-sided scanning using one optical sensor on each side.

Although one embodiment of the present invention has been described above based on the drawings,
The invention also applies in other aspects.

For example, in the above embodiment, the four rod-shaped vibration damping members 2
6.28.30.32 are provided, but the damping members 26.28 may be removed, as shown in FIG.

In this way, by bringing the damping members 30 and 32 into contact with the back surface of the movable mirror 20, the dimensions of the movable mirror 20 can be reduced, so that the drive energy of the reciprocating drive device and the vibration energy of the entire system are reduced. There are advantages.

In addition, the damping members 26, 28, 30, 32 may be members having other shapes than rods, and the material thereof is made of damping alloy in the above embodiment, but other materials may be used. It may be made of metal, plastic, or rubber, or a composite material thereof.

In addition, the vibration damping members 26, 28, 30, 32 are connected to the movable mirror 20.
It does not have to be located within the rotation range.

That is, even if the movable mirror 20 is located outside the rotation range,
If the movable mirror 20 is provided at a position where it comes into contact with the deflection of the movable mirror 20, a certain effect can be obtained.

Further, in the above embodiment, a pair of laminated piezoelectric actiniators 22 and 24 were provided, but only one pair may be provided.

In addition, the stacked piezoelectric actuator 22 can be created using a lever mechanism.
．． The amount of drive required for 24 may be further reduced,
In place of the laminated piezoelectric actuator 22.24, a moving magnet, a moving coil, a piezoelectric actuator provided with electrodes for torsional movement, Te, rfe
Other types of drive devices may be used, such as drive devices using giant magnetostrictive alloys such as nol-D, hydraulic pressure, pneumatic pressure, and thermal deformation.

Further, the movable mirror 20 may have a rectangular shape similar to the fixed mirror 14.

It should be noted that the above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of drawings]

FIG. 1 is a perspective view illustrating the configuration of a multiple reflection type beam scanning device according to an embodiment of the present invention. FIG. 2 is a plan view showing in detail the positional relationship between the movable mirror and the damping member of the embodiment shown in FIG. FIG. 3 is a diagram showing the amount of charge injected for driving the laminated piezoelectric actuator of the embodiment shown in FIG. 4 to 9 are diagrams for explaining the multiple reflection and deflection operations of the embodiment shown in FIG. 1, and FIGS. 4 and 5 are a plan view and a side view of the movable mirror and the fixed mirror in a parallel state. , FIGS. 6 and 7 are a plan view and a side view of the movable mirror rotated counterclockwise, and FIGS. 8 and 9 are a plan view and a side view of the movable mirror rotated clockwise, respectively. It shows. FIG. 10 is a diagram showing the movable mirror in a stationary state using the finite element analysis method, and FIG. 11 is a diagram showing the deflection that occurs when the rotation direction is switched using the finite element analysis method. FIG. 12 is a diagram corresponding to FIG. 2 showing another embodiment of the present invention. 14: Fixed mirror 20: Movable mirror 22.24: Laminated piezoelectric actuator (reciprocating drive device) 26.28, 30, 3゛2: Vibration damping member Fig. 1

Claims (1)

[Scope of Claims] A movable mirror that is rotatably provided around one axis, a reciprocating drive device that rotates the movable mirror back and forth, and a reciprocating drive device that is provided in a fixed position opposite to the movable mirror and is connected to the movable mirror. A multiple reflection type light beam scanning device comprising a fixed mirror for performing multiple reflections and reciprocating scanning by changing the deflection angle of the reflected light by rotating the movable mirror back and forth. 1. A multiple reflection type beam scanning device, characterized in that a damping member is provided at a distal end portion of the movable mirror and comes into contact with the movable mirror to suppress deflection vibration that occurs when the movable mirror is switched in a reciprocating direction.