JPH04244790A - Electrostatic micromotor - Google Patents

Abstract

PURPOSE:To simplify the drive system for an electrostatic micromotor. CONSTITUTION:A rotor 1 comprising a plurality of blade pieces and a stator 2 comprising a multiplicity of blade pieces 4 extending oppositely to the blade pieces 3 are formed on a semiconductor substrate. Each of the blade pieces 3, 4 is provided with an electromagnetic wave/electric signal converting element which is irradiated with electromagnetic wave to produce charges for electrostatically driving the rotor.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic micromotor used in micromachines having a size of several mm or less.

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, and the voltage used is high relative to the size of the motor. Special consideration must be given to voltage resistance 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 problems, and includes a plurality of blades of a rotor and a plurality of blades extending to face the blades. By forming a PN junction of the same polarity from the surface side of each of these blades, providing electromagnetic wave-to-electrical conversion elements on these blades, and irradiating each element with electromagnetic waves. Different charges are generated on the front and back surfaces of each blade, and the rotor is rotated by the electrostatic force generated by the charges.

[0006]

[Operation] According to the present invention, an electromagnetic wave-to-electrical conversion element such as a solar cell is provided in the rotor and stator, and the rotor and stator are made to face each other face to face, and the Coulomb force generated between the facing faces is used. Since driving force is used, the rotor can be rotated simply by irradiating the rotor and stator with electromagnetic waves such as sunlight, without applying a high driving voltage from the outside.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 are an enlarged sectional view and a top view of essential parts of an electrostatic micromotor according to the present invention, where 1 is a rotor and 2 is a stator of the electrostatic motor. These rotor 1 and stator 2 are based on a semiconductor silicon substrate, and the rotor diameter is approximately 200 μm, and the rotation is Spacing between child 1 and stator 2: 1 to 2 μm
, the thickness of the rotor 1 and stator 2 is approximately 1 μm. Here, the major difference from the previously proposed structure is that the plurality of blades 3, 3... of the rotor 1 extend to the lower surface of the blades 4, 4... of the stator 2, and the rotor 1
a plurality of blades 3, 3... and a large number of blades 4 of the stator 2.
, 4... are facing each other, and a pn junction 5 is formed near the surface of each blade 3, 3... of the rotor 1 by a method such as implanting impurities, and pn near the surface of one side of each blade 4, 4... of the stator 2.
A junction 6 is formed. And these pn junctions 5,
Reference numeral 6 constitutes an electromagnetic wave-to-electrical conversion element 7 typified by a solar cell that generates electric power when irradiated with electromagnetic waves such as sunlight. When sunlight 8 is irradiated onto the blades 3, 3, etc. of the rotor 1, a positive charge is generated on the front side and a negative charge is generated on the back side, as shown in Fig. 1. An electrostatic force is generated between the rotor 1 and the stator 2, which face each other face to face, due to the electric charges. At this time, the electromagnetic wave-to-electric conversion element 7 provided on the stator 1 is not provided on the entire surface of the blade 4, but is provided only on one side of the blade 4, as shown by diagonal lines in FIG.

On the other hand, the rotor 1 of the motor generally has a rotating shaft (
rotor 1 and stator 2.
The electrostatic force generated between the two does not act as a force to bring the rotor 1 closer to the stator 2.

At this time, the electromagnetic wave-to-electric conversion element 7 provided on the stator 1 is provided only on one side of the blade 4, as shown by diagonal lines in FIG. The electrostatic force acts as a force that rotates the rotor 1.

That is, positive charges are generated in the parts of the rotor 11 that are not covered by the stator 26, and the parts of the rotor 11 that are not covered by the stator 26 are
Since a negative charge is generated on the back surface of the electromagnetic wave-to-electric conversion element 71, a leftward rotational force acts on the rotor 11. Further, the positive charges on the surface of the electromagnetic wave irradiated portion of the rotor 12 are attracted to the negative charges on the back surface of the electromagnetic wave-to-electric conversion element 72 of the stator 22. Furthermore, the rotor 13 and the electromagnetic wave-electric conversion element 74,
Similarly, a force that rotates the rotor 1 to the left is generated between the rotor 14 and the electromagnetic wave-to-electric conversion element 75. As a result, the rotor 1 rotates to the left.

The electrostatic force acting between the rotor 1 and stator 2 will now be explained. As shown in Figure 3, thickness 1
When sunlight 8 is irradiated on the electromagnetic wave-to-electrical conversion element 7 made of a μm single-crystal silicon substrate, positive and negative charges are generated.The silicon substrate is regarded as a dielectric material, and the electric charge is transferred to the front and back of the substrate for electromagnetic wave-to-electrical conversion. In order to generate the open circuit voltage of the element, the amount of charge Q is

0012

[Math 1]

Here, as shown in FIG. 4, when the electrostatic attraction force F is calculated by considering the charge amount of each of the rotor 1 and stator 2 as point charges with an area of 1 μm2,

[0014]

[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.

0016
]

[Math 3]

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

In addition, in FIGS. 1 and 2, the rotor 1 has four poles and the stator 2 has six poles for ease of explanation, but these numbers of poles can be changed arbitrarily. Of course.

Furthermore, the electromagnetic waves irradiated to the electromagnetic wave-to-electrical conversion element are not limited to sunlight, and in addition to sunlight, light from short wavelengths in the ultraviolet range to long wavelengths in the infrared range can also be used. Furthermore, if a focused laser beam with a high energy density per unit area is used, it will be possible to obtain a large torque as an electrostatic motor.

[0020]

[Effects of the Invention] As is clear from the above description, the present invention has the following advantages:
It has a plurality of rotor blades and a number of stator pieces extending to face each blade, and a PN junction of the same polarity is formed from the surface side of each blade. These blades are provided with electromagnetic wave-to-electric conversion elements, and by irradiating each element with electromagnetic waves, different charges are generated on the front and back surfaces of each blade, and the rotor is rotated by the electrostatic force caused by the charges. Therefore, the motor can be rotated without supplying driving power from outside the micromachine. Furthermore, since the energy supply for driving the motor is made wireless, the degree of freedom in the behavior of the micromachine increases and its range of applications can be expanded.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of essential parts of an electrostatic motor of the present invention.

FIG. 2 is an enlarged top view of essential parts of the electrostatic motor of the present invention.

FIG. 3 is an explanatory diagram for calculating the amount of charge in the electrostatic motor of the present invention.

FIG. 4 is an explanatory diagram for calculating electrostatic attraction force in the electrostatic motor of the present invention.

[Explanation of symbols]

1 Rotor 2 Stator 3 Rotor blades 4 Stator blades 7 Electromagnetic wave-electric conversion element

Claims (1)

[Claims] 1. An electrostatic method in which a semiconductor rotor and stator are formed on a semiconductor substrate by making full use of lithography technology, and the rotor is rotated by an electrostatic force acting between the rotor and the stator. A micromotor consists of a plurality of rotor blades and a number of stator pieces extending to face the blades, and a PN junction of the same polarity is connected from the surface side of each blade. By irradiating each element with electromagnetic waves, different charges are generated on the front and back surfaces of each wing, and the electrostatic force caused by the charges causes the rotor to move. An electrostatic micromotor that rotates.