JPH06217507A - Miniature motor and method for driving it - Google Patents

Abstract

PURPOSE:To reduce the size of a miniature motor by constituting the driving coil of the motor of bar-shaped coils arranged in parallel on the upper and lower surfaces of the rotor of the motor and contact coil sections in which one ends of the coils are connected to the upper and lower surfaces of the rotor. CONSTITUTION:The driving coil 4 of the motor is composed of bar-shaped coil sections 5 and contact coil sections 6 and the sections 5 are arranged in parallel on the upper and lower surfaces of a rotor 3. The contact coil sections 6 are wound around the rotor 3 while one ends of the coils sections 5 formed on the upper and lower surfaces of the rotor 3 and connected to the upper and lower surfaces of the rotor 3. Since an induced current flows to a supporting shaft 2 when the rotor 3 rotates, the rotor 3 can be continuously rotated in the same direction by detecting the induced current through the shaft 2 and discriminating the magnitude and polarity of the current with a microcomputer, and then, controlling the flowing direction of the current to the coil 4. Therefore, the size and driving energy of the miniature motor can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a very fine micromotor of micron order and a driving method thereof.

[0002]

2. Description of the Related Art At present, in addition to sensors and electronic circuits, attempts are being made to integrate a small mechanical system (micromachine) having a moving mechanism called an actuator on a silicon substrate or the like. Such an integrated system is realized by a photo application used for manufacturing a VLSI. That is, a mask pattern is transferred, a window is opened in the resist, and a removal process of etching a base material through the window, and an adhesion process of electrolytically plating a window portion to form a metal structure are performed. In addition, a complex structure can be made by joining the substrates processed in this way, and the solid phase is used for precise joining by utilizing the interfacial reaction. The technology for making a complex integrated system in this way is called micromachining.
In such a complicated mechanical system, it becomes impossible to control without an information processing function inside, so it is essential to incorporate an electronic circuit that carries intelligence and communication functions.To that end, single crystal silicon that can coexist with the electronic circuit should be used. It is basically used as a substrate material.

By the way, recently, as a driving device in micromachining, research on a micromotor which is rotationally driven by electromagnetic force has been actively conducted. FIG. 5 is a side sectional view illustrating the structure of a conventional micromotor. In the figure, 51 is a silicon substrate, and a spindle 52 is formed on the silicon substrate 51. Also,
Reference numeral 53 in the figure denotes a rotor fitted to the support shaft 52, and the rotor 53 is rotatable around the support shaft 52. Further, reference numeral 54 in the drawing is a drive coil for applying a rotational force to the rotor 3, and the drive coil 54 is the rotor 53.
It is installed around. In the conventional micromotor, the rotor 53 can be rotated by supplying current to the drive coil 54 to generate a magnetic field and electromagnetic induction when the magnetic field is changed at a predetermined timing.

[0004]

However, in the above-described conventional micromotor, since the drive coil 54 for applying the rotational force to the rotor 53 is installed around the rotor 53 in a large number, only the drive coil 54 is provided. This occupies more than half of the total installation area of the motor, which has been a major obstacle to miniaturization of the micromotor.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a micromotor capable of further miniaturization.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and includes a support shaft formed on a base, a rotor rotatable about the support shaft, and a rotor. In a micromotor provided with a drive coil for applying a rotational force, a drive coil is wound around a rotor, and the drive coil includes rod-shaped coil portions arranged in parallel on the upper and lower surfaces of the rotor, respectively. , A contact coil portion in which one end of each of the rod-shaped coil portions is connected between the upper and lower surfaces of the rotor.

Further, in the above-mentioned micromotor driving method, an induced current generated by the rotation of the rotor is detected through a support shaft, and the flow direction of the current supplied to the drive coil is controlled based on the detected induced current. It was done like this.

[0008]

In the micromotor and the method of driving the same of the present invention, the drive coil for applying the rotational force to the rotor is incorporated in the rotor itself, and the current supplied to the drive coil is based on the induced current detected through the support shaft. By controlling the flow direction of the rotor, it becomes possible to rotate the rotor around the support shaft.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1A and 1B are views for explaining an embodiment of a micromotor according to the present invention, in which FIG. 1A is a plan view and FIG. 1B is a side sectional view. In the figure, reference numeral 1 is a silicon substrate as a base, and a spindle 2 is formed on the silicon substrate 1. Reference numeral 3 in the drawing denotes a rotor fitted to the support shaft 2, and the rotor 3 is rotatable around the support shaft 2. Further, in the figure, 4 is the rotor 3
It is a drive coil for applying a rotational force to the.

In the structure of the micromotor of this embodiment, the drive coil 4 is wound around the rotor 3 itself, which is a rotating body. That is, the drive coil 4 is composed of a rod-shaped coil portion 5 and a contact coil portion 6, of which the rod-shaped coil portion 5 is arranged side by side on the upper surface and the lower surface of the rotor 3, respectively. In addition, the contact coil portion 6 has one end of each of the rod-shaped coil portions 5 formed on the upper and lower surfaces of the rotor 3 at the rotor 3
The upper and lower surfaces are connected. With this structure, the drive coil 4 is wound around the rotor 3. In the figure, 7 is a silicon oxide film formed on the silicon substrate 1,
Further, in the figure, 8 is an electrode film, 9 is an electrode part, and these are for supplying a current from a power source (not shown) to the drive coil 4.

Next, a specific manufacturing process for obtaining the micromotor of this embodiment will be described with reference to FIGS. First, as shown in FIG. 2A, the spindle 2 is formed on the silicon substrate 1 by dry etching by resist patterning, and then the entire surface is oxidized to form the silicon oxide film 7 on the silicon substrate 1. Form. Next, as shown in FIG. 2B, an electrode film 8 made of tungsten is formed on the silicon oxide film 7 and patterned, and nickel titanium is sputtered on the electrode film 8 and patterned. As a result, the electrode portion 9 made of nickel titanium is formed at the tip of the electrode film 8. continue,
As shown in FIG. 2C, the oxide film 1 is formed by oxidizing silicon.
0 is formed, and then a tungsten film is formed thereon and patterned to form the rod-shaped coil portion 5 made of tungsten on the oxide film 10.

Next, as shown in FIG. 3A, an insulating film 11 made of silicon nitride is formed on the entire surface, a cobalt layer 12 is further deposited thereon, and an insulating film 13 made of silicon nitride is formed. Subsequently, as shown in FIG. 3B, a contact hole 14 is formed in the cobalt layer 12 by dry etching, and then an insulating film 15 is formed on the side wall of the contact hole 14 by cobalt oxidation. Next, as shown in FIG. 3C, a tungsten film is formed on the inside of the contact hole 14 and on the upper surface of the cobalt layer 12, and then a bar-shaped tungsten film is formed on the upper surface of the cobalt layer 12 and its inside by dry etching by patterning. The coil portion 5 and the contact coil portion 6 are formed. After that, the oxide film 10 on the silicon substrate 1 is immersed in diluted hydrofluoric acid.
Only those are removed by selective etching, whereby a micromotor as shown in FIG. 1 is built on the silicon substrate 1.

Next, a method of driving the micromotor in this embodiment will be described with reference to FIG. First, in FIG. 4, a spindle 17 formed on a silicon substrate 1 is connected to a microcomputer 17 via an ammeter 16. A power source 18 is connected to the microcomputer 17, and a current is supplied from the power source 18 to the electrode film 8 on the silicon substrate 1. Here, of the north, south, east, and west, if the right side in the figure is north and the left side is south, the direction of current flow from the power source 18 at the time of startup is the direction of arrow A. As a result, the rotor 3 is magnetized, and the right side of the rotor 3 becomes the N pole and the left side becomes the S pole in accordance with the winding direction of the drive coil 4 and the current flow direction. Therefore, the rotor 3 rotates due to the attraction with the earth's magnetism. To start.

When the rotor 3 starts rotating in this way, an induced current flows through the support shaft 2, so this induced current is detected through the support shaft 2 and its magnitude and polarity are determined by the microcomputer 17. At this time, the magnitude of the induced current gradually decreases as the right side of the rotor 3, that is, the N-pole side, approaches the south direction, and reaches a minimum when completely facing the south direction. The microcomputer 17 detects the time when this induced current becomes the minimum, and at that time, the direction of the current flow from the power source 8 is switched to the opposite direction, that is, the direction of arrow B. Then, contrary to the previous case, the right side of the rotor 3 becomes the N pole, and the rotational force is applied to the rotor 3 again. After that, if the flow direction of the current to the drive coil 4 is controlled by the microcomputer 17 as in the above, the rotor 3 can be continuously rotated in the same direction.

[0015]

As described above, according to the present invention,
A drive coil for applying rotational force to the rotor is built into the rotor itself, and the rotor can be rotated by controlling the flow direction of the supply current to the drive coil based on the induced current detected through the spindle. Therefore, compared to the conventional structure in which a drive coil is installed around the rotor, the micromotor can be made even smaller and the geomagnetism is used to rotate the motor. It also saves energy.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an embodiment of a micromotor according to the present invention.

FIG. 2 is a diagram (No. 1) for explaining the manufacturing process of the micromotor in the embodiment.

FIG. 3 is a diagram (No. 2) explaining the manufacturing process of the micromotor in the embodiment.

FIG. 4 is a diagram illustrating a driving method of a micromotor.

FIG. 5 is a side sectional view illustrating a structure of a conventional micromotor.

[Explanation of symbols]

 1 Silicon Substrate (Base) 2 Spindle 3 Rotor 4 Drive Coil 5 Rod Coil 6 Contact Coil

Claims (2)

[Claims] 1. A micromotor comprising a support shaft formed on a base body, a rotor rotatable around the support shaft, and a drive coil for applying a rotational force to the rotor, wherein The drive coil is wound, wherein the drive coil includes rod-shaped coil portions arranged in parallel on the upper and lower surfaces of the rotor, and one end of each of the rod-shaped coil portions between the upper and lower surfaces of the rotor. A micromotor comprising a connected contact coil portion. 2. The method of driving a micromotor according to claim 1, wherein an induced current generated by rotation of the rotor is detected through the support shaft, and is supplied to the drive coil based on the detected induced current. A method of driving a micromotor, characterized in that the direction of current flow is controlled.