JPH04261373A - Electrostatic motor - Google Patents

Abstract

PURPOSE:To simplify the driving system of an electrostatic motor. CONSTITUTION:A driving electrode 6 is arranged closely to a semi-conductor disk substrate 1 provided in a freely rotatable state, and electromagnetic wave- electricity transducing elements 51, 52 whose main bodies are p-n junctions are formed by doping specified impurities into the above-mentioned semiconductor substrate 1. And the above-mentioned semiconductor substrate 1 is rotated by suction force or repulsive force, generated by charges produced on the element surfaces by emitting an electromagnetic wave to the electromagnetic wave-electricity transducing elements 51, 52 in the vicinity of the above- mentioned driving electrode 6 and an electric field applied to the above- mentioned driving electrode 6.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic motor useful as a drive source for micromachines, which has attracted attention in recent years.

0002

[Prior Art] In recent years, micromachines with a size of several mm,
Micromachines of a smaller size or smaller have been proposed, and various research and development efforts have been carried out. As a drive source that mechanically drives the micromachine, a semiconductor rotor and stator are formed using photolithography technology on semiconductors such as silicon, and act between the rotor and stator. An electrostatic micromotor that rotates a rotor using electrostatic force has been prototyped (for example, "Journal of the Robotics Society of Japan" 8).
(See Vol. 4, August 1990, p. 63 et seq.).

0003

[Problem to be solved by the invention] However, the electrostatic force in this prototype electrostatic micromotor depends on the Coulomb force between the points generated by electric charges between the tips of the rotor blades and the tips of the stator pieces. Therefore, in order to obtain a large driving force, it is necessary to use a high voltage of 100 V or more. However, the prototype micromotor is extremely small, with a rotor diameter of about 200 μm and a distance between the rotor and stator of 2 to 3 μm. , it is necessary to pay special consideration to the withstand voltage between stators and between adjacent stators.

[0004] Furthermore, in order to drive the stator, a high voltage source of 100 V or more is required to be applied to the stator, and the peripheral circuitry for controlling the high voltage is also large.

[0005]

[Means for Solving the Problems] The present invention has been made in view of the above-mentioned problems, and includes a drive electrode arranged close to a rotatably provided semiconductor substrate. An electromagnetic wave-to-electrical conversion element mainly consisting of a pn junction is formed by doping impurities, and by irradiating the electromagnetic wave to the electromagnetic wave to the electromagnetic wave near the drive electrode with electromagnetic waves, charges generated on the element surface and applied to the drive electrode. The semiconductor substrate is rotated by an attractive force or a repulsive force generated by an electric field.

[0006]

[Operation] Since the semiconductor substrate to be rotationally driven is charged with electromagnetic wave irradiation, the semiconductor substrate is rotationally driven by simply applying an electric field to the drive electrode without controlling the conduction or disconnection of the electric field.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view conceptually showing the electrostatic motor of the present invention. In this figure, reference numeral 1 denotes a semiconductor substrate made of a semiconductor material such as silicon in the shape of a disk, and is configured to be freely rotatable by a pivot means (not shown). The size of this semiconductor substrate 1 is 20 to 200 μm in diameter,
The thickness is approximately 1 to several μm. And this semiconductor substrate 1
A large number of regions 31,
It is electrically divided into 32, . Further, impurities such as boron and phosphorus are doped into these many regions 31, 32, .
... is formed. These pn junctions 41, 42,
. . . constitute electromagnetic wave-to-electrical conversion elements 51, 52, . . . typified by solar cells that generate electricity when irradiated with electromagnetic waves such as sunlight. 6 is a semiconductor substrate 1
A drive electrode made of a metal conductor placed close to the surface of the
For example, they are arranged opposite to one region 38 of the semiconductor substrate 1, and a + or - electric field is applied thereto.

As shown in FIG. 1, the semiconductor substrate 1 has a p-type on the front side and an n-type on the back side, and when a negative electric field is applied to the drive electrode 6, a region 38 corresponding to the drive electrode 6 is Adjacent areas 31 are irradiated with sunlight 7. Then, the electromagnetic wave-electric conversion element 51 in the area 31 irradiated with sunlight 7
starts generating electricity, and a + charge is generated on the p-type surface side. As a result, an attractive force due to an electrostatic force generated between the positive charge and the negative electric field of the drive electrode 6 is generated between the region 31 and the drive electrode 6, and the semiconductor substrate 1, which is rotatably pivoted, It is rotated in the right direction as indicated by the arrow. When the region 31 rotates and enters the shadow of the drive electrode 6, the region 31 and the drive electrode 6
The electrostatic force between the areas 31 and 31 disappears, but the area 3
2 is now irradiated with sunlight 7, and this time an electrostatic force is generated between this region 32 and the drive electrode 6, and the semiconductor substrate 1
is continuously driven to rotate. In the same configuration, if the electric field applied to the drive electrode 6 is made positive, a repulsive force will be generated between the positive charge generated on the surface of the region 31 irradiated with sunlight, and the semiconductor substrate 1 will rotate counterclockwise. become.

FIG. 2 shows another embodiment of the invention,
The difference from the embodiment shown in FIG. 1 is that the semiconductor substrate 1 is constituted by a donut-shaped disk, and the central portion of the semiconductor substrate 1 that does not contribute to rotational drive is removed.
The weight of the semiconductor substrate as a rotor is reduced, and a large momentum can be obtained.

FIG. 3 is an improved version of the embodiments shown in FIGS. 1 and 2, and is an embodiment in which two or more driving electrodes 6 are arranged to obtain a larger rotational driving force. . That is, light shielding plates 81 and 82 are provided on one side of the plurality of drive electrodes 61 and 62 to block light, and the other side is configured to allow light to reach the regions 31 and 35 of the semiconductor substrate 1. In such a configuration, when the entire surface of the semiconductor substrate 1 is irradiated with sunlight 7,
The sunlight 7 reaches only the regions 31 and 35 that are not covered by the electrodes 61 and 62 and the light shielding plates 81 and 82, and the semiconductor substrate 1 is rotated between these regions 31 and 35 and the drive electrodes 61 and 62. A driving force is generated. According to this embodiment, rotational driving force can be obtained at a plurality of locations on the semiconductor substrate 1, so that a larger driving force can be generated than in the embodiments shown in FIGS. 1 and 2.

FIG. 4 also shows another embodiment of the present invention,
In this embodiment, impurities are introduced from the circumferential direction of the semiconductor substrate 1 to form pn junctions 41 and 42 parallel to the outer circumference of the substrate 1.
... is formed. And each area 31, 32, ・
The drive electrodes 6, which are arranged in close proximity to the drive electrodes 6, are provided at positions facing the outer circumferential surface of the substrate 1. In this embodiment, the sunlight 7 is also irradiated from the outer peripheral direction of the region 31 . As a result, as in the embodiments shown in FIGS. 1 and 2, the semiconductor substrate 1 is moved to the right by the attractive force or repulsive force generated between the electric charge generated on the outer peripheral surface of the region 31 and the drive electrode 6. , or rotationally driven to the left.

FIG. 5 shows yet another embodiment of the present invention. In all of the embodiments shown in FIGS. 1 to 4, an electric field is supplied to the drive electrode 6 from outside the motor, but in this embodiment, an electric field is also supplied to the drive electrode 6 by an electromagnetic wave-to-electricity conversion element such as a solar cell. It uses an electric field. That is, an electromagnetic wave-to-electrical conversion element 9 made of a pn junction is provided adjacent to the drive electrode 6, and this element 9 and the drive electrode 6 are directly electrically connected. Then, by irradiating the region 31 of the semiconductor substrate 1 and this electromagnetic wave-to-electric conversion element 9 with electromagnetic waves such as sunlight 7, an electric field generated in the electromagnetic wave-to-electric conversion element 9 and guided to the drive electrode 6; Electromagnetic wave-electric conversion element 5 in region 31
The semiconductor substrate 1 is rotationally driven by the repulsive force or attractive force generated between the semiconductor substrate 1 and the electric charge generated in the semiconductor substrate 1 . According to the electrostatic motor shown in FIG. 5, all driving force is provided by energy from electromagnetic waves, so the motor itself can be made completely wireless.

Let us now consider the electrostatic force that acts between the semiconductor substrate 1 and the drive electrode 6 in the motor having the configuration shown in FIG. As shown in FIG. 6, an electromagnetic wave-to-electrical conversion element 5 made of a single crystal silicon substrate with a thickness of 1 μm,
In addition, sunlight 7 is applied to the electromagnetic wave-electric conversion element 9 for the drive electrode.
When irradiated with , positive and negative charges are generated, and the silicon substrate is regarded as a dielectric, and the amount of charge Q is

[0014]

[Math 1]

Here, as shown in FIG. 7, when the electrostatic attraction force F is calculated by regarding the amount of charge on each of the semiconductor substrate 1 and the drive electrode 2 as point charges with an area of 1 μm2,

[0016]

[Math 2]

Assuming that the radius r of the rotor 1 is 100 μm, the torque T acting on the rotor 1 is as follows.

0018
]

[Math 3]

##EQU1## is obtained, and the rotor 1 starts rotating by irradiating it with electromagnetic waves, for example sunlight.

[0020] Furthermore, the electromagnetic wave-electric conversion elements 51, 52...
・The electromagnetic waves irradiated are not limited to sunlight;
In addition to sunlight, light in the ultraviolet range with short wavelengths and light in the infrared range with long wavelengths can be used as well, and if focused laser light with high energy density per unit area is used, it can be used as an electrostatic motor to generate large torque. you will be able to get it.

[0021]

Effects of the Invention As is clear from the above description, the present invention comprises a rotatably provided semiconductor substrate and a drive electrode placed close to it, and a pn junction is formed by doping the semiconductor substrate with a predetermined impurity. forming an electromagnetic wave-to-electrical conversion element, and irradiating the electromagnetic wave to the electromagnetic wave-to-electrical conversion element near the drive electrode, thereby generating an attractive force generated by an electric charge generated on the element surface and an electric field applied to the drive electrode; Since the semiconductor substrate is rotationally driven by repulsive force, the means for supplying driving energy is simplified, and it is also possible to drive only by electromagnetic waves such as sunlight, making it possible to wirelessly drive micromachines and other micromachines. can be expected.

[Brief explanation of the drawing]

FIG. 1 is a conceptual perspective view showing an embodiment of the electrostatic motor of the present invention.

FIG. 2 is a conceptual perspective view showing another embodiment of the electrostatic motor of the present invention.

FIG. 3 is a conceptual perspective view showing still another embodiment of the electrostatic motor of the present invention.

FIG. 4 is a conceptual perspective view showing different embodiments of the electrostatic motor of the present invention.

FIG. 5 is a conceptual perspective view showing still another embodiment of the electrostatic motor of the present invention.

FIG. 6 is an explanatory diagram for calculating the amount of charge in the electrostatic motor of the present invention.

FIG. 7 is an explanatory diagram for calculating electrostatic attraction force in the electrostatic motor of the present invention.

[Explanation of symbols]

1 Semiconductor substrate 2 Separation strip 3 Area 4 pn junction 5 Electromagnetic wave-electric conversion element 6 Drive electrode 7 Sunlight 8　　　　　　　　　　　　　 9 Electromagnetic wave-electric conversion element

Claims (6)

[Claims] [Claim 1] A semiconductor substrate provided rotatably;
and a drive electrode disposed close to the substrate, doping the semiconductor substrate with a predetermined impurity to form an electromagnetic wave-to-electrical conversion element mainly consisting of a pn junction, and forming an electromagnetic wave-to-electrical conversion element near the drive electrode. The semiconductor substrate is characterized in that an electric charge is generated on the surface of the element by irradiating electromagnetic waves, and the semiconductor substrate is rotationally driven by an attractive force or a repulsive force generated by this electric charge and an electric field applied to the drive electrode. electrostatic motor. 2. The electrostatic motor according to claim 1, wherein the charge to the drive electrode is supplied from an electromagnetic wave-to-electric conversion element that generates a charge when irradiated with electromagnetic waves. 3. The electrostatic motor according to claim 1, wherein the semiconductor substrate is disk-shaped. 4. The electrostatic motor according to claim 1, wherein the semiconductor substrate is a donut-shaped disk. 5. The electrostatic motor according to claim 1, wherein the semiconductor substrate is doped with impurities in the thickness direction to form a pn junction parallel to the substrate surface. . 6. The electrostatic capacitor according to claim 1, wherein the semiconductor substrate is doped with impurities from the circumferential direction to form a pn junction parallel to the outer periphery of the substrate. motor.