JPH01145622A - Optical scanning device - Google Patents

Abstract

PURPOSE:To scan a light beam in two dimensions by one mirror by providing a permanent magnet on the flank of a mirror and supplying a current to a driving coil which is arranged opposite it. CONSTITUTION:A permanent magnet piece 14 is provided on the opposite flank of the mirror 11 from its fulcrum and the driving coil 15 is fixed to a support base 12 on the surface facing the permanent magnet 14 across a proper gap and connected to a driving signal 16. Then the current is supplied to the driving coil 15 to generate a magnetic attractive or repulsive force between the permanent magnet 14 and driving coil 15 and this force displaces the mirror 11 in a direction perpendicular to its reflecting mirror, so that the mirror 11 slants by an optional angle in two dimensions. The light beam incident on the mirror 11 is therefore deflected and the current is controlled to scan the light beam. Consequently, the small-sized, integrated two-dimensional scanner is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical scanning device that scans a light beam by deflecting a mirror at high speed.

A conventional method for reading the contents of technical documents, photographs, drawings, etc. is to irradiate the surface of an object with a two-dimensional light beam and convert the reflected light from the object into an electrical signal.

As a method for two-dimensionally scanning light, a method that generally uses a combination of means for horizontally scanning a light beam and means for vertically scanning the light beam is used. - As means for scanning in the dimensional (horizontal or vertical) direction, the galvanometer scanner shown in FIG. 5(a), the rotating polygon mirror scanner shown in FIG.
) hologram disk scanner. In the galvanometer scanner, as shown in FIG. 5(a), by energizing the coil of the foundation stone, the rotating shaft on which the mirror 1 is mounted rotates in proportion to the magnitude of the current. A light beam 2 is incident on the mirror 1 from the direction 1a, and when the shaft 3 rotates as shown by the arrow 1b, the light beam 4 reflected by the mirror 1 is deflected in the direction of the arrow IC. This galvanometer scanner is often used because it is small and has a simple structure. However, when performing continuous scanning, the movement is a reciprocating rotational movement of the mirror 1, and since acceleration and deceleration time is always required, there is an upper limit to the scanning speed. Moreover, the weight of the mirror 1 becomes a load and has a disadvantage that it affects the scanning characteristics.

The rotating polygon mirror scanner emits light beam 2 as shown in the same figure (b).
It is composed of a polygon mirror 5 having a plurality of reflecting mirrors on the circumference, and is used by rotating at high speed around a rotation axis 6. The light beam 2 is incident from the direction 1d, and when the polygon mirror 5 having N faces is rotated l/N, the light beam 2 is scanned in the direction of the arrow 1e.

When the polygon mirror 5 rotates once, the light beam 2 is scanned N times. Although this method is suitable for high-speed scanning, it has the disadvantage of increasing cost because it requires a highly accurate polygonal mirror.

A hologram disk scanner is a hologram disk scanner that has been the subject of recent research. As shown in FIG. 7C, the hologram disk 7 has a hologram deflection pattern 7.
a, 7b, 7c... are provided on the circumference of the hologram disk 7, the light beam 2 is incident from the direction 1f, and when the hologram disk 7 rotates in the direction of the arrow 1g, it forms a hologram deflection pattern. The corresponding light beam 2 is scanned in the direction of arrow 1h. This method has a simple structure and is expected to achieve high-speed scanning, but the hologram disk 7
The shape of the light beam exiting the scanner and the uniformity of the scanning speed are inferior to scanners using mirrors. In addition, the hologram disk has the disadvantage that the light utilization rate is not sufficient, which limits its uses.

By the way, none of the scanners shown in FIGS. 5(a), 5(b), and 5(c) can perform two-dimensional scanning with each individual scanner. Therefore, in general, these scanners are used, for example, for fast-dimensional scanning in the horizontal direction, and a combination scanner is used that uses a galvanometer scanner for scanning in the vertical direction.

Problems to be Solved by the Invention Conventional means for two-dimensionally scanning a light beam configures a two-dimensional scanning device by combining scanners that deflect horizontally and vertically separately. In this case, the scanners of each dimension are disposed perpendicular to the two dimensions, and the incident optical path and output optical path are defined, which poses a problem that limits the use of the apparatus. Another disadvantage is that the scanner itself is large.

The present invention aims to provide a two-dimensional compact integrated running device that solves the above-mentioned problems of the prior art.

Means for Solving the Problems In order to achieve the above object, the present invention provides a permanent magnet on the side surface of the mirror, a drive coil at a position facing the permanent magnet, and a current flowing through the drive coil. This is what I did.

Effect In the above configuration, by passing a current through the drive coil, a magnetic attraction or repulsion force is generated between the permanent magnet and the drive coil, and this force displaces the mirror in a direction perpendicular to its reflection surface, causing the mirror to move. tilts to an arbitrary angle in two dimensions. Therefore, the light beam can be deflected by the mirror (two people), and the light beam can be scanned by controlling the current.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a basic configuration diagram of a one-dimensional deflection scanner in a first embodiment of the present invention.

The light beam reflecting mirror 11 has an upper surface as a reflecting surface as shown in the figure, and is fixed to a support base 12 by a linear fulcrum 13. A permanent magnet piece 14 is provided on the opposite side of the mirror 11 from the fulcrum, and the mirror 11 can move about the fulcrum 13 in a moving direction 17 shown by an arrow. Permanent magnet 1
A drive coil 15 is fixed to the support base 12 (the fixed part is not shown) on the surface facing the support base 12 with a suitable gap between the drive coil 15 and the drive coil 15 and connected to a drive signal 16. Now, if the polarity of the permanent magnet 14 provided on the mirror 11 is set to the N pole toward the upper surface of the mirror 11 and the S pole toward the lower surface of the mirror 11, and the drive signal 16 is not applied, the mirror 11 will not move and will remain in the center. It is stationary at a point (not shown).

Next, when a current is applied so that the top surface of the drive coil 15 becomes the north pole and the bottom surface becomes the south pole, a reaction occurs between the permanent magnet 14 and the drive coil 15, and the permanent magnet 14 is pushed upward in the moving direction 17. It will be done. As a result, the mirror 11 is
It can be tilted about the fulcrum 13. Next, drive coil 15
When the applied current is reversed, an S pole is generated on the upper surface of the drive coil 15 and an N pole is generated on the lower surface, the permanent magnet 14 and the drive coil 15 are attracted to each other, and the mirror 11 is moved in the moving direction 1.
7 and is now tilted in the opposite direction.

Assuming that the drive signal 16 is a triangular wave whose current polarity is reversed as shown in FIG. When the mirror 11 vibrates in the direction 17 and a light beam such as a laser beam is irradiated onto the upper surface of the mirror 11, the reflected light is deflected in proportion to the displacement of the mirror 11, and one-dimensional scanning of the light beam is performed.

Next, an embodiment of a one-dimensional scanner using the present invention is shown in FIG. A permanent magnet 241 is attached to one side of the light beam deflection mirror 21, and a permanent magnet 24 is attached to the opposite side.
2 is installed. And two permanent magnets 241
, 242 are provided with drive coils 251 and 252 facing each other with an appropriate interval. mirror 2
1 between the support base 22, drive coils 251 and 252
A buffer support material 28 is provided for the purpose of preventing the device from falling when the device is not energized, and for use in continuous repetitive motion. For example, the upper surfaces of permanent magnets 241 and 242 shown in Fig. 3 are both N.
When a drive signal 261 that applies current to the drive coil 251 of a magnet whose bottom surface is an S pole and a current is applied such that the top surface of the drive coil 251 is an S pole and the bottom surface is a N pole, the drive coil 251 and An attractive force acts between the magnet 241 and the magnet 241, and the magnet 241 is displaced downward. At this time, the mirror 21 fixed to the magnet 241 is also displaced downward. On the other hand, when a drive signal 262 of opposite polarity to the drive signal 261 is applied to the drive coil 252 provided on the opposite surface, the upper surface of the drive coil 252 becomes N polarity (the drive coil 252 and the permanent magnet 242 have a repulsive effect). As a result, the permanent magnet 242 and the mirror 21 fixed thereto are displaced upward.Permanent magnets 241 and 2
If the forces acting on 42 are in opposite directions and have the same magnitude, then
The mirror 21 is tilted in one direction about the central axis (not shown) of the mirror 21. Next, when the signals applied to the drive signals 261 and 262 are set to have opposite polarities to the polarity of the applied signals, the mirror 21 is tilted in a direction opposite to the rest point. By repeatedly performing this operation, the mirror 21 becomes
A light beam that vibrates around a stationary point and is incident at a fixed angle is continuously scanned in one dimension.

FIG. 4 shows an embodiment of a two-dimensional light beam scanning device that realizes two-dimensional mirror deflection by applying the embodiment of FIG. 3 to other orthogonal sides of the mirror.

The same parts in the figure as in FIG. 3 are given the same reference numerals.

Permanent magnets 341 and 342, drive coils 351 and 352, and drive signals 361 and 362 constitute a one-dimensional scanning system along the Y axis. On the other hand, permanent magnet 241
, 242, drive coils 251, 252, and drive signals 261, 262 constitute a Y-axis one-dimensional scanner.

Now, when performing two-dimensional sequential scanning, for example, currents with opposite polarities are used as a pair of driving signals 361 and 362 around the X axis, and by applying these to the driving coils 351 and 352, the mirror 21 is Deflect one cycle in the axial direction. Next I: Currents with opposite polarities are used as drive signals 261 and 262 for the Y-axis.1, drive coil 251,
252, the beam is deflected by one M pixels in the Y-axis direction. This is repeated M times to complete one two-dimensional scan. The amount by which the mirror 21 is caused to swing can be determined by the current value.

Effects of the Invention As described above, the present invention provides a permanent magnet on the side surface of a mirror, and by passing a current through a drive coil placed opposite to the permanent magnet, the mirror is displaced in a direction perpendicular to the surface thereof, and light is emitted onto this mirror surface. Optical scanning is performed by irradiating a beam, and it is possible to scan the optical beam two-dimensionally using a single mirror, making it possible to obtain a compact integrated optical scanner, which is easy to use. The scope of use can be expanded without any restrictions.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of essential parts in an embodiment of the optical scanning device according to the present invention, FIG. 2 is a waveform diagram of a drive signal in the optical scanning device according to the present invention, and FIGS. 3 and 4 are respective views of the optical scanning device according to the present invention. A perspective view of main parts in another embodiment of the device, FIG.
FIGS. 1A, 2B, and 2C are perspective views for explaining the operating principle of a conventional optical scanning device. 11.21... Mirror, 12, 22... Support stand,
13...Fulcrum, 14, 241, 242, 34
1, 342... permanent magnet, 15, 251, 25
2, 351, 352... Drive coil, 16°26
1, 262, 361, 362... drive signal, 2
8...Buffer support material. Name of agent: Patent attorney Toshi Nakao (only 1 person!) !
31 Figure [211

Claims (3)

[Claims] (1) A permanent magnet having magnetic polarity in a direction perpendicular to the reflective surface of the mirror is provided on the side surface of the mirror or the mirror holding material, and a drive coil is provided at a position facing the permanent magnet,
An optical scanning device characterized in that the mirror is deflected by applying a current to the drive coil to generate a magnetic field. (2) A patent characterized in that drive coils are provided independently on opposing sides of the mirror or mirror holding material, and current is applied to the opposing drive coils so as to generate magnetic fields in opposite directions. An optical scanning device according to claim 1. (3) Claim 2, characterized in that it has two pairs of drive coils provided on the side surfaces of opposing mirrors or mirror holders, and the pairs of drive coils are installed orthogonally to each other. The optical scanning device described.