JPH01182822A - Beam scanner - Google Patents

Abstract

PURPOSE:To increase the scanning speed furthermore and to make a device low-cost and small-sized by installing a supporting plate, which a reflection mirror is stuck and is provided with the hinge part of a partially elastic member, on displace faces of two piezoelectric elements to constitute an optical deflector and oscillating two piezoelectric elements while shifting oscillation timings from each other by a half period to oscillate the reflection mirror. CONSTITUTION:The light from an LD light source 1 is condensed on a reflection face by a condenser lens 2, and a supporting plate 9 which has a reflection mirror 10 stuck and is provided with the hinge part of the partially elastic member is installed on respective displace faces of two piezoelectric elements 11 and 12 to constitute the deflector which deflects the laser beam, and two piezoelectric elements 11 and 12 are oscillated while shifting oscillation timings from each other by a half period to oscillate the reflection mirror 10. Thus, high speed scanning is possible and the device is miniaturized and realized at a low-cost.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electron beam scanning system such as a laser beam printer.

(Prior art) Recently, a recording method that records an image by optically scanning a recording medium with a laser beam whose intensity is modulated by an image signal corresponding to the image pattern to be recorded has come into use in printers, facsimile receiving devices, etc. It has come to be below,
To explain the conventional example using FIG. 4, the laser beam emitted from the LD light source 1 after being intensity-modulated by the image signal is as follows.
The collimator lens 2a converts the light into a substantially parallel light beam, which enters the deflection means of the rotating polygonal chain 3, and is deflected by the deflection means at substantially constant angular velocity. The deflected laser beam enters fθ lenses 4a and 4b, and the fθ
The light is focused onto the recording surface 20 of a photosensitive recording medium by the θ lenses 4a and 4b, and the recording surface 20 is scanned in accordance with the deflection. The fθ lens has a function of correcting the deflection of the laser beam that occurs at a uniform angular velocity so that its focused spot moves uniformly on the recording surface. That is, a laser beam that enters the entrance pupil at an angle of θ with respect to the optical axis of an fθ lens having a focal length Hf is focused on the recording surface at a position at a distance of fθ from the optical axis. For this reason, it is given the name fθ lens.

(Problems to be Solved by the Invention) In the above-mentioned conventional optical configuration, a rotating polygon mirror of a rotating polygon mirror type is used as a deflector for deflecting a light beam, and the scanning speed is higher than that of a galvanometer mirror using an oscillating mirror. However, even if a high-speed rotating polygon mirror, for example a hexahedral polygon mirror, is rotated at 30,000 ppm, it can only scan 3,000 times per second. This is becoming more difficult due to the performance limits of the motor.

(Means for Solving the Problems) In order to achieve the above object, the present invention focuses light from an LD light source 1 onto a reflective surface using a condensing lens 2, and uses a deflector that deflects the laser beam to reflect the light from the LD light source 1. A support plate 9 to which a mirror 10 is fixed and which is provided with a hinge part p made of a partially elastic material is formed by extending over the displacement surfaces of each of the two piezoelectric elements 11.12, so that the two piezoelectric elements 11.12 are The reflecting mirror 10 is oscillated by being vibrated with a half period shift from each other.

(Function) According to the present invention, since a deflector using a piezoelectric element with a very fast response speed is used as a deflector, high-speed scanning is possible, and miniaturization and cost reduction can be realized.

(Example) FIG. 1 is a diagram illustrating an example of the present invention.
A laser beam emitted from a D light source 1 after being intensity-modulated by an image signal is incident on a reflecting mirror 10 by a condensing lens 2, and is deflected at a constant angular velocity by swinging the reflecting mirror 1°.

The deflected laser beam passes through the fθ lens 5a.

5b, and the recording surface 20 is optically scanned by the fθ lenses 5a and 5b.

A deflector for swinging the reflecting mirror 10 will be explained using FIG. 2. For the two piezoelectric elements 11.12, a support plate 9 having a hinge part made of a partially elastic material, which is installed on the member 8 and to which the reflection mirror 10 is fixed, is installed on the displacement surface of the piezoelectric elements 11.12. FIG. 3 shows a detailed view of the support plate 9.
The support plate 9 is a rigid body whose hatched portion is made of an elastic material p to form a hinge portion, and the adhesive surface 0 is fixed to the piezoelectric elements 11 and 12.

Piezoelectric elements play the role of converters to convert electrical energy into mechanical energy such as stress and displacement.Recently, piezoelectric elements with laminated ceramic layers have been developed, and the response speed is several tens of microseconds. It has achieved high reliability and can withstand severe expansion and contraction with a thickness of 16 μm. When such a piezoelectric element is used in the above configuration, the piezoelectric element 11
．． 12 displacement arrows A and B are vibrated at 16 μm,
The distance l between the support plates 9 is set at 64 μm, and the piezoelectric element 11
．． 12 is vibrated by shifting it by half a period.

The swing angle θ of the mirror 10 is 30 degrees, and the laser beam is
It can be deflected by 0 degrees. If this is vibrated at a response speed of 50 microseconds, scanning can be performed 50,000 times per second.

(Effects of the Invention) As described above in detail, according to the present invention, a deflector using a piezoelectric element has been realized, so that the scanning speed can be increased, and the cost and size can be reduced. This is what I did.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing an embodiment of the present invention, Fig. 2 is a detailed diagram of the deflector of the present invention, Fig. 3 is a detailed diagram of the support plate, and Fig. 4 is a schematic diagram showing a conventional example. . 1... LD light source 2... Condensing lens 3...
・Rotating polygon mirror 2a...Collimator lens 4a
, 4b, 5a, 5b-fθ lens 8...member 9...support plate 10...
Mirrors 11, 12...Piezoelectric element 20...
Recording surface p...Elastic material patent registration applicant
Copal Electronics Co., Ltd. Figure 2 11 Piezoelectric element＼

Claims (1)

[Claims] In a beam scanning device that uses an optical deflector to scan light from a light source on a scanning surface, the optical deflector is connected to a supporting plate having a reflecting mirror fixed to it and a hinge part made of a partially elastic material, which is connected to two piezoelectric elements. 1. A beam scanning device, characterized in that the reflecting mirror is oscillated by oscillating the two piezoelectric elements, which are installed on respective displacement surfaces and are shifted by a half period from each other.