JPH03145620A - Optical scanner - Google Patents

Abstract

PURPOSE:To miniaturize and thin the optical scanner by adding a function as a hologram disk to a disk substrate and allowing it to have a function as a rotor of an electrostatic motor. CONSTITUTION:A rotor electrode 10 for rotating a disk substrate 4 and a hologram 5 for diffracting a laser light 30 are provided on a common disk substrate 4. When a power source supplies a voltage so that the disk substrate 4 is rotated by electrostatic suction force or electrostatic resiliency generated between the rotor electrode 10 and a stator electrode 20, the disk substrate 4 rotates by a principle of an electrostatic motor, and a diffraction grating on the disk substrate 4 can execute an optical scan by diffracting the laser light 30 from a light source. In such a way, a function as a hologram disk is added to the disk substrate, and also, it can be allowed to have a function as a rotor of the electrostatic motor, and the whole optical scanner can be miniaturized and made thin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical scanning device, and particularly to an optical scanning device using a diffraction grating used in an image forming device and an image reading device.

[Prior Art] An optical scanning device using a diffraction grating scans a laser beam onto a scanning surface using a hologram disk, which is made up of a plurality of holograms manufactured by holography technology and arranged in an arc shape as a diffraction grating. A hologram scanner that forms an image or scans a laser beam onto a document to read the image is common. The hologram disk is rotated by a motor around its central axis of rotation, and laser light is diffracted by each hologram to perform scanning with the laser light. In a hologram scanner, the optical system can be simplified because the hologram can have linear scanning, aberration-free, and constant-velocity scanning functions. For this reason, hologram scanners are becoming smaller and thinner than conventional optical scanning devices using rotating polygon mirrors.

[Problems to be Solved by the Invention] It is desired that optical scanning devices be made smaller and thinner, but in the conventional optical scanning device using a diffraction grating as described above, permanent magnets and Since a motor with a coil is used, there is a limit to miniaturization and thinning.

An object of the present invention is to provide an optical scanning device that can be further reduced in size and thickness.

[Means for Solving the Problems] According to the present invention, the object includes: a coherent light source, a disk substrate, a fixed substrate arranged parallel to the disk substrate with a predetermined gap therebetween; a shaft support means rotatably supported on a fixed substrate; a plurality of diffraction gratings arranged on the disk substrate along the circumferential direction of the disk substrate for diffracting light from the coherent light source; a rotor electrode provided on the surface of the disk substrate on the fixed substrate side; and a rotor electrode provided on the fixed substrate so as to face the rotor electrode at a predetermined distance with respect to the central axis of rotation of the disk substrate. a stator electrode having a plurality of electrode pairs arranged radially; This is achieved by an optical scanning device characterized by comprising a power source that sequentially supplies voltage to the electrode pairs.

[Function] In the optical scanning device of the present invention, the fixed substrate and the disk substrate are arranged in parallel with a predetermined gap between them, and the disk substrate is rotatably supported by the fixed substrate by the pivoting means. , a plurality of diffraction gratings are arranged on the disk substrate along the circumferential direction of the disk substrate, and a rotor electrode is provided on the surface of the disk substrate on the fixed substrate side. A stator electrode consisting of a plurality of electrode pairs arranged above is provided on the fixed substrate so as to face the rotor electrode at a predetermined interval.

A power supply sequentially supplies a voltage to each electrode pair so as to rotate the re-disk substrate by electrostatic attraction or repulsion generated between the rotor electrode and the stator electrode. Therefore,
According to the present invention, a disk substrate is rotated by the principle of an electrostatic motor, and a diffraction grating on the disk substrate diffracts laser light from a coherent light source to perform optical scanning. Here, since the rotor electrode for rotating the disk substrate and the diffraction grating for diffracting the laser beam are provided on the common disk substrate, in addition to the function as a hologram disk, the disk substrate also has an electrostatic charge. It can also function as a rotor of a motor, making it possible to make the entire optical scanning device smaller and thinner.

These effects of the present invention will become clearer from the following examples of the present invention, and other effects of the present invention will become clearer.

[Example] Embodiments of the present invention will be described based on the drawings.

An optical scanning device ↓, which is an embodiment of the present invention, is shown in the basic configuration diagram in the first construction drawing.

A semiconductor laser 2, which is an example of a coherent light source, generates coherent laser light 30. The coherent light source may be a well-known gas laser, liquid laser, or solid state laser other than a semiconductor laser.

The disk substrate 4 is made of an insulating substrate. The insulating substrate is preferably a single crystal substrate such as Si, which is used to form semiconductor elements such as ICs (integrated circuits) and LSIs (large scale integrated circuits). Along the circumferential direction of the disk substrate 4, a plurality of holograms 5 as diffraction gratings are formed at equal intervals in an arc shape at the circumferential edge of the disk substrate 4.

The hologram 5 is directly formed on the disk substrate 4 by a well-known holography technique using two-beam interference. The grating pitch of each hologram 5 changes sequentially along the circumferential direction of the disk substrate 4 so that the diffracted laser beam 31 linearly scans along a predetermined scanning line 51 as the disk substrate 4 rotates. There is.

The hologram 5 is formed on a dielectric thin film such as 5in2, Tie, etc. formed on the SI substrate forming the disk substrate 4, and the dielectric film is formed into a multilayer structure and is made to increase and reverse to increase the diffraction efficiency. It may be configured. In addition to the hologram 5, the diffraction grating may be a diffraction grating formed by electron beam technology or micromachining technology.

A beam shaping lens 3 is arranged in front of the semiconductor laser 2, and the action of the lens 3 and the hologram 5 suppresses the spread of the laser beam 31 diffracted by the hologram 5 on the imaging plane 50. , the laser beam 31 on the imaging plane 50 is shaped into an appropriately shaped spot without aberration. Note that the beam shaping lens 3 is not necessarily necessary, and the lattice pattern of the hologram 5 is configured so that the laser beam 31 on the imaging plane 50 is shaped into a spot of an appropriate shape without aberration by the independent action of the hologram 5. You can leave it there.

The fixed substrate 6 is arranged parallel to the disk substrate 4 with a predetermined gap therebetween.

FIG. 2 shows a sectional view of the main part of the optical scanning device 1-.

The fixed substrate 6 is made of an insulating substrate, and the insulating substrate is preferably a single crystal substrate such as Si, which is used to form semiconductor elements such as ICs and LSIs.

A shaft body 7 is provided on the disk substrate 4, and a bearing 8 is provided on the fixed substrate 6. By inserting the shaft body 7 into the bearing 8, the disk substrate 4 is fixed to the fixed substrate 6 so as to be rotatable around its rotation center axis 9. In this way, the shaft support means is composed of the shaft body 7 and the bearing 8. The bearing 8 is preferably a rolling bearing having a pole bearing, an air bearing using dynamic pressure action, or a magnetic bearing using magnetic action. Particularly when an air bearing or a magnetic bearing is used, the entire shaft support means can be made more compact, which is advantageous in making the optical scanning device l smaller and thinner.

The rotor electrode 10 is provided on the bottom surface of the disk substrate 4 on the side facing the fixed substrate 6. The rotor electrode IO is made of metal or semiconductor material.

The rotor electrode 10 supports semiconductor devices such as ICs and LSIs.
It is preferable that the disk substrate 4 is formed on the disk substrate 4 by a well-known technique similar to that used on a substrate such as an i-substrate. AI on the redisk board 4,
Forming a thin film such as Au5Cu, then applying a photoresist on the thin film, then masking the portion to be the rotor electrode 10, and exposing the photoresist to form a pattern,
Finally, the photoresist is removed to form the rotor electrode 10. In this way, it is possible to form the rotor electrode 10 as finely as a semiconductor element such as an IC or LSI.

Stator electrode 20 is provided on fixed substrate 6 so as to face rotor electrode 10 at a predetermined interval. The stator electrode 20 is made of a conductive material such as a metal material or a semiconductor. As with the rotor electrode 10, the stator electrode 20 is preferably formed on the fixed substrate 6 by a well-known technique similar to that used for forming semiconductor elements such as IC and LSI on a substrate such as a Si substrate. ，
It can be formed as finely as a semiconductor element such as an LSI. Incidentally, when forming the stator electrode 20 in this manner, a pattern of lead wiring for connecting the stator electrode 20 to the outside may be formed on the fixed substrate 6 at the same time. Furthermore, when forming the stator electrode 20, or
A semiconductor element as a peripheral circuit may be formed on the fixed substrate 6 before or after forming the stator electrode 20. In this case, it is particularly advantageous to reduce the size and thickness of the entire device including the peripheral circuit. .

Since the rotor electrode IO and the stator electrode 20 can be formed finely in this way, the mechanism for rotating the disk substrate 4 can be made dramatically smaller and thinner than a motor using permanent magnets and coils. .

Since the hologram 5 can be formed finely by holography technology using two-beam interference, the optical scanning device 1 can be dramatically downsized and thinned by using the small and thin disk substrate 4 and fixed substrate 6. It becomes possible to create -.

0 An example of the stator electrode 20 is shown in a plan view in FIG. As is clear from the figure, the stator electrode 20 has three
It has three electrode pairs 21a and 21b, 22a and 22b, and 23a and 23b. Electrode pair 21a and 21
b 22a and 22h1 and 23a and 23b are
They are arranged radially at equal intervals with respect to the rotation center axis 9.

FIG. 4 shows an example of the rotor electrode 10 in a plan view. This figure is a view of the disk substrate 4 viewed from below.
As is clear from the figure, the rotor electrode 10 has a substantially elliptical planar shape having one end 11 and the other end 12, and is arranged coaxially with the rotation center axis 9. Therefore, one end 11 of the rotor electrode 10 is connected to one end 21 of the electrode pair.
a, 22a, or 23a, when the other end 12 of the rotor electrode 10 faces the other 2 of the corresponding electrode pair
1b, 22b, or 23b.

Hereinafter, using FIGS. 5A, 5B, and 5C, the power source 1
The method of supplying voltage to the stator electrode 20 of No. 5 and the mechanism of rotating the disk substrate 4 in the optical scanning device 1 will be explained. FIGS. 5A, 5B, and 1-5C are views showing the disk substrate 4 and fixed substrate 6 conceptually developed along the circumferential direction of the disk substrate 4, respectively. In these figures, the rotor electrode 10 is indicated by its ends 11 and 12 and their shorting line 13. Power source 15 also supplies voltage to stator electrodes 20 via line 16 .

FIG. 5A shows the initial state, in which the rotor electrode 10 is located closest to the electrode pair 21a and 21b. In this case, the power supply 15 applies a voltage between the electrode pairs 21a and 21b such that the potential is lower than one of the electrode pairs 21a or the other electrode pair 21b.

Therefore, one electrode pair 21a is negatively charged, and the other electrode pair 21b is positively charged. Then, the electrode pair 21
a and 21b and one end 11 and the other end 12 of the rotor electrode IO, respectively, work as a capacitor with air as a dielectric material through a predetermined gap, and the end 11 is positively charged and the end 12 is negatively charged. At this time, due to the attractive force of the positive charges and the negative charges, the end portions 11 and 12 tend to move to the middle point, that is, the position where the rotor electrode 10 and the electrode-2 pair 21a and 21b overlap most, so that the rotor Torque is generated in the electrode 10 around the rotation center axis 9 as shown by the arrow, and the disk substrate 4 rotates. Such voltage supply to the electrode pair 21a and 21b of the power source 15 is performed only for a certain period of time. Rotor electrode 1
Immediately before the ends 11 and 12 of 0 reach the aforementioned midpoints, the supply of the voltage is stopped, and thereafter the disk substrate 4 continues to rotate due to inertia.

In the state shown in FIG. 5B, a voltage is applied from the power source 15 between the electrode pair 22a and 22b to which the rotor electrode 10 approaches. Then, as in the case of the electrode pair 21a and 21b, torque is generated in the rotor electrode 10 around the rotation center axis 9, and the disk substrate 4 rotates.

The voltage is supplied to the electrode pair 22a and 22b of the power source 15 only for a certain period of time, and the voltage is supplied to the electrode pair 22a and 22b of the power source 15 for a certain period of time, and the voltage is supplied immediately before the end 11 and the end 12 of the rotor electrode 10 respectively reach the above-mentioned midpoint. After the supply is stopped, the disk substrate 4 continues to rotate due to inertia.

In the state shown in FIG. 5C, a voltage is applied from the electric current I@i15 between the electrode pair 23a and 23b to which the rotor electrode 310 approaches. Then, as in the case of the electrode pair 21a and 21b, torque is generated in the rotor electrode 10 around the rotation center axis 9, and the disk substrate 4 rotates.

The voltage is supplied to the electrode pair 23a and 23b of the power supply 15 only for a certain period of time, and the voltage is supplied to the electrode pair 23a and 23b of the power source 15 for a certain period of time, and the voltage is supplied immediately before the end 11 and the end 12 of the rotor electrode IO respectively reach the above-mentioned midpoint. After the supply is stopped, the disk substrate 4 continues to rotate due to inertia.

The voltage supply from the power source 15 is sequentially performed so as to repeat the operations shown in FIGS. 5A, 5B, and 5C.

In this way, the rotor electrode 10 constituting the three-phase motor
The disk substrate 4 continues to rotate at a constant speed due to the electrostatic attraction force generated between the stator electrode 20 and the stator electrode 20 .

In the above embodiment, the electrostatic motor composed of the rotor electrode 10 and the stator electrode 20 has three phases, but it may have two phases or four or more phases. Further, although the disk substrate 4 is rotated by electrostatic attraction force, it may also be rotated by electrostatic repulsion force. By applying a negative or positive voltage to the rotor electrode IO and sequentially applying the same voltage to the stator electrode 20 as that of the rotor electrode 10, the disk substrate 4 can be rotated by electrostatic repulsion. In addition, the stator electrode 20 and the rotor electrode 10
In order to rotate the disk substrate 4 by electrostatic attractive force, the predetermined interval between the two is preferably as narrow as possible, or it is preferably from several μm to several tens of μm in consideration of manufacturing errors of each component.

The operation of the optical scanning device configured as above will be explained.

First, a laser beam 30 that is a diverging or converging beam generated from the semiconductor laser 2 is incident on the hologram 5 . The incident laser beam 30 is diffracted according to the diffraction pattern of the hologram 5. The diffracted laser light 31 forms an image on the imaging plane 50. At this time, since the disk substrate 4 is rotating at a constant speed and the hologram grating pitch changes sequentially along the circumferential direction of the disk substrate 4, the diffracted laser beam 3
The diffraction angle of 1 changes over time, and as a result, the laser beam is linearly scanned along the scanning line 51 on the imaging surface 50.

In the above embodiment, the hologram 5 is attached to the disk substrate 4.
The rotor electrode 10. is provided on the bottom surface opposite to the side facing the fixed substrate 6. It may be provided in any part of the disk substrate 4 as long as the optical action as a diffraction grating is not inhibited by other components such as the fixed substrate 6, and it may be provided on the bottom surface of the disk substrate 4 on the fixed substrate G side. It may be provided in

Further, in the above embodiment, the hologram 5 is a reflective hologram, but the rotor electrode 10. The hologram 5 may be a transmission type hologram as long as it is configured so that the optical function as a diffraction grating is not inhibited by other components such as the fixed substrate 6.

When the hologram 5 is a transmission type hologram, a transparent substrate such as a glass substrate may be used as the disk substrate 4.

[Effects of the Invention] According to the optical scanning device of the present invention, the rotor electrode for rotating the disk substrate and the diffraction grating for diffracting the laser beam are provided on the common disk substrate. , the disk substrate can have a function as a rotor of an electrostatic motor in addition to a function as a hologram disk, and the entire optical scanning device can be made smaller and thinner.

In particular, it is possible to form rotor electrodes and diffraction gratings on a disk substrate and to form stator electrodes on a fixed substrate using the same well-known technology used to form semiconductor elements such as ICs and LSIs on substrates. It becomes possible to configure a mechanism for rotating the substrate as finely as a semiconductor element such as an IC or LSI. Moreover, since the diffraction grating can be formed finely using holography technology, electron beam technology, or micromachining technology, it is possible to dramatically reduce the size and thickness of optical scanning using small and thin disk substrates and fixed substrates. It becomes possible to provide the device.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram showing an embodiment of the present invention, FIG. 2 is a cross-sectional view of a main part configuration showing an embodiment of the present invention, and FIG. 3 is a plan view showing an example of a stator electrode according to the present invention. FIG. 4 is a plan view showing an example of a rotor electrode according to the present invention, and FIGS. 5A, 5B, and 5C are conceptual development views showing a rotation mechanism of a disk substrate according to the present invention. Sat... Optical scanning device, 2... Semiconductor laser, 3... Beam shaping lens, 4...
Disk substrate, 5... Hologram, 6...
...Fixed substrate, 7...Shaft body, 8...Bearing, 9...Rotation center shaft, 10...Rotor electrode, 11.12...・End of rotor electrode, 15・
...Power supply, 20...Stator electrode, 21a,
21b... Electrode pair, 22a122b...
... Electrode pair, 23a, 23b... Electrode pair,
30.31... Laser light, 50... Imaging surface. 51...Scanning line. 8 Japanese Unexamined Patent Publication No. 3 145620 (6)

Claims (1)

[Claims] a coherent light source, a disk substrate, and a fixed substrate arranged parallel to the disk substrate with a predetermined gap therebetween;
a pivot means for rotatably supporting the disk substrate on the fixed substrate; and a plurality of pivot means arranged on the disk substrate along the circumferential direction of the disk substrate for diffracting light from the coherent light source. a diffraction grating, a rotor electrode provided on a surface of the disk substrate on the fixed substrate side, and a rotor electrode provided on the fixed substrate so as to face the rotor electrode at a predetermined interval; The disk substrate is rotated by an electrostatic attractive force or an electrostatic repulsive force generated between a stator electrode having a plurality of electrode pairs arranged radially with respect to a central axis, and the rotor electrode and the stator electrode. An optical scanning device comprising: a power source that sequentially supplies a voltage to each of the electrode pairs.