JP3166378B2 - Micromotor and driving method thereof - Google Patents

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 micro motor of the order of a micron and a driving method thereof.

[0002]

2. Description of the Related Art At present, attempts are being made to integrate a small mechanical system (micro machine) having a motion mechanism called an actuator in addition to sensors and electronic circuits on a silicon substrate or the like. Such an integrated system is realized by a photo application used for manufacturing an VLSI. That is, a mask pattern is transferred, a window is formed in the resist, a removal process of etching a base material from the window, and an attachment process of electrolytic plating the window portion to form a metal structure are performed. In addition, a complex structure can be formed by joining the substrates processed in this manner, and the joining is precisely performed using an interface reaction in a solid phase. The technique of making a complex monolithic system in this way is called micromachining.
Since such complex mechanical systems cannot be controlled unless they have an information processing function inside, it is indispensable to incorporate electronic circuits that perform intelligence and communication functions. Basically, it is used for a substrate material.

[0003] Recently, as a driving device in micromachining, research on a micromotor that 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, reference numeral 51 denotes a silicon substrate, on which a support shaft 52 is formed. Also,
In the figure, reference numeral 53 denotes a rotor fitted to the support shaft 52, and the rotor 53 is rotatable about the support shaft 52. Further, in the figure, reference numeral 54 denotes a drive coil for applying a rotational force to the rotor 3.
It is installed around. In the conventional micromotor, a current is supplied to the drive coil 54 to generate a magnetic field, and the rotor 53 can be rotated by electromagnetic induction when the magnetic field is changed at a predetermined timing.

[0004]

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

[0005] The present invention has been made to solve the above problems, and has as its object 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 has 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 rotating force, a drive coil is wound around a rotor, and the drive coil has a bar-shaped coil portion arranged side by side on the upper and lower surfaces of the rotor, respectively. And a contact coil portion in which one end of each bar-shaped coil portion is connected between the upper and lower surfaces of the rotor.

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

[0008]

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

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a view for explaining an embodiment of a micromotor according to the present invention, in which (a) is a plan view and (b) is a side sectional view. In the figure, reference numeral 1 denotes a silicon substrate as a base, on which a support shaft 2 is formed. In the figure, reference numeral 3 denotes a rotor fitted to the support shaft 2, and the rotor 3 is rotatable about the support shaft 2. Further, in FIG.
Is a drive coil for applying a rotational force to the motor.

In the configuration of the micromotor of this embodiment, the driving coil 4 is wound around the rotor 3 itself, which is a rotating body. That is, the drive coil 4 includes the bar-shaped coil section 5 and the contact coil section 6, of which the bar-shaped coil section 5 is arranged in parallel on the upper surface and the lower surface of the rotor 3. The contact coil portion 6 is formed by connecting one end of each of the bar-shaped coil portions 5 formed on the upper and lower surfaces of the rotor 3 to the rotor 3.
Are connected between the upper and lower surfaces. With such a configuration, the drive coil 4 is wound around the rotor 3. In the figure, reference numeral 7 denotes a silicon oxide film formed on the silicon substrate 1,
In the figure, reference numeral 8 denotes an electrode film, and 9 denotes an electrode portion, which supplies 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, a support shaft 2 is formed on a silicon substrate 1 by dry etching by resist patterning, and thereafter, the entire surface is oxidized to form a 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 further, nickel titanium is sputtered from the electrode film and patterned. As a result, an electrode portion 9 made of nickel titanium is formed at the tip of the electrode film 8. continue,
As shown in FIG. 2C, the silicon is oxidized to form an oxide film 1.
0 is formed, and then tungsten is formed thereon and patterned to form a bar-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 thereafter, a bar-like shape is formed on the upper surface of the cobalt layer 12 and the inside thereof by dry etching by patterning. The coil part 5 and the contact coil part 6 are formed. Thereafter, the oxide film 10 on the silicon substrate 1 is immersed in diluted hydrofluoric acid.
Is 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 microcomputer 17 is connected to a support shaft 2 formed on a silicon substrate 1 via an ammeter 16. A power supply 18 is connected to the microcomputer 17, and a current is supplied from the power supply 18 to the electrode film 8 on the silicon substrate 1. Here, assuming that the right side in the figure is north and the left side is south in the east-west north-south direction, the flow direction of the current from the power supply 18 at the time of startup is defined as the arrow A direction. 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 according to the winding direction of the drive coil 4 and the current flow direction. To start.

When the rotor 3 starts rotating, an induced current flows through the support shaft 2. The 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 becomes minimum when the rotor 3 completely faces the south direction. The microcomputer 17 detects the time when the induced current is minimized, and at that time, the direction of current flow from the power supply 8 is switched to the opposite direction, that is, the direction of the arrow B is switched. Then, contrary to the above, the right side of the rotor 3 becomes the N pole, and the rotational force is again applied to the rotor 3. Thereafter, if the direction of current flow to the drive coil 4 is controlled by the microcomputer 17 as described above, the rotor 3 can be kept rotating 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 direction of current supplied to the drive coil based on the induced current detected through the support shaft. Therefore, compared to the conventional structure in which the drive coil is installed around the rotor, the size of the micromotor can be further reduced, and the drive is performed because the earth magnetism is used for the rotation of the motor. It also saves energy.

[Brief description of the drawings]

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

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

FIG. 3 is a diagram (part 2) for explaining the manufacturing process of the micromotor in the embodiment.

FIG. 4 is a diagram for explaining a driving method of a micromotor.

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

[Explanation of symbols]

 Reference Signs List 1 silicon substrate (substrate) 2 support shaft 3 rotor 4 drive coil 5 rod-shaped coil 6 contact coil

Claims (2)

(57) [Claims] 1. A micromotor comprising: a support shaft formed on a base; 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 has a rod-shaped coil portion arranged in parallel on the upper and lower surfaces of the rotor, and one end of each of the rod-shaped coil portions is disposed between the upper and lower surfaces of the rotor. A micromotor comprising a contact coil portion connected to the micromotor. 2. The method for driving a micromotor according to claim 1, wherein an induced current generated by rotation of the rotor is detected through the support shaft, and supplied to the drive coil based on the detected induced current. A method for driving a micromotor, wherein a direction of current flow is controlled.