Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Patent
1995-10-19
1997-02-25
Phan, James
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
359198, 359224, 359900, G02B 2610
Patent
active
056064470
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a mirror galvanometer suitable for example for laser beam scanning systems and the like, and in particular to a miniaturized planar type mirror galvanometer and its method of manufacture.
BACKGROUND ART
Mirror galvanometers are used for example in laser scanners which deflection scan a laser beam, operating on the theory that when an electrical current is passed through a movable coil arranged in a magnetic field, an electromagnetic force is generated due to the interaction between the electrical current and the magnetic field, producing a rotational force (torque) proportional to the electrical current. The construction involves a device using galvanometer theory with a movable coil rotating to an angle where the torque and a spring force are in equilibrium, the presence or absence and size of a current being detected by an indicator needle swung by the movable coil. However instead of the indicator needle a reflecting mirror is provided on a member which rotates with the movable coil.
In practice mirror galvanometers use for example a movable piece of iron instead of the movable coil arranged in a magnetic field, with a magnetic path formed around the periphery of the movable piece of iron by means of a magnetic body involving two permanent magnets and four magnetic poles. The magnetic flux between the poles is altered by changing the size and direction of a current flowing in a drive coil wound around the magnetic body, so that a reflecting mirror is swung by the movable piece of iron, to thus deflection scan a laser beam (see for example "Practical Laser Technics", Kyoritsu Publishing Company, Dec. 20 1987, p210-212).
With the development of microelectronics represented by the high integration of semiconductor devices, there is now a range of equipment which is both highly functional as well as being miniaturized, and laser scanning systems and the like which use the abovementioned mirror galvanometer thus become applicable, as with laser adapted equipment such as laser microscopes. There is also a requirement for even further miniaturization.
With the conventional mirror galvanometer however, further miniaturization is difficult due for example to the movable coil being mechanically wound. Therefore, further miniaturization of laser scanning systems using such mirror galvanometers, and the laser adapted equipment using such laser scanning systems becomes difficult.
The present invention takes into consideration the above situation, with the object of providing for further miniaturization of laser scanning systems and laser adapted equipment using such laser scanning systems, by achieving miniaturization of the mirror galvanometer.
DISCLOSURE OF THE INVENTION
Accordingly, the mirror galvanometer of the present invention comprises; a semiconductor substrate having a planar movable plate and a torsion bar for axially supporting the movable plate so as to be swingable in a perpendicular direction relative to the semiconductor substrate formed integrally therewith, a planar coil for generating a magnetic field by means of an electric current, laid on an upper face peripheral edge portion of the movable plate, and a reflecting mirror provided on an upper face central portion which is surrounded by the planar coil, and magnets forming pairs with each other arranged so as to produce a magnetic field at the planar coil portions on the opposite sides of the movable plate which are parallel with the axis of the torsion bar.
With such a construction, since the movable mirror portion is formed on the semiconductor substrate using a semiconductor element manufacturing process, then the mirror galvanometer can be made much smaller than conventional mirror galvanometer, thereby enabling miniaturization of laser scanning systems which deflection scan a laser beam.
The movable plate may comprise; a frame shape outer movable plate axially supported relative to the semiconductor substrate by a first torsion bar, and an inner movable plate axially supported inside th
Asada Norihiro
Esashi Masayoshi
Phan James
The Nippon Signal Co. Ltd.
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