An electrothermal MEMS torsion actuator

Abstract

An electrothermal MEMS torsion actuator, characterized in that the electrothermal MEMS torsion actuator 1 is a thin film structure composed of at least two materials with different thermal expansion coefficients, one end of the electrothermal MEMS torsion actuator is fixed, and the other end is connected to a movable unit 2, the center line 3 of the electrothermal MEMS torsion actuator is not perpendicular to the fixed end surface, and the slope of the center line 3 has no inflection point, when the temperature of the electrothermal MEMS torsion actuator 1 rises, the electrothermal MEMS torsion actuator 1 rotates around the x-axis direction, thereby driving the movable unit 2 to rotate. Advantages: It solves the technical problem that the existing electrothermal MEMS actuator is not easy to twist, and has the characteristics of simple structure and easy implementation.

Description

Technical Field

[0001] The invention relates to an electrothermal MEMS torsion actuator, belonging to the technical field of MEMS application. Background Art

[0002] MEMS drive methods are mainly divided into four types: electrostatic, electromagnetic, electrothermal and piezoelectric. Among them, electrostatic and electromagnetic are commonly used in torsional drive methods. Electrothermal is usually applied to vertical displacement and is difficult to apply to torsional drive. Even if it is applied to torsional drive, its structure is very complicated. For example, Patent Document 1, A Micro-Electromechanical System Torsion Mirror Driver, Manufacturing Method and Application (200410053563.3), discloses an implementation scheme of electrostatic drive for torsional state. Summary of the invention

[0003] The technical problem to be solved by the present invention is how to twist the electrothermal MEMS driver.

[0004] The technical solution of the present invention is an electrothermal MEMS torsion actuator, characterized in that the electrothermal MEMS torsion actuator 1 is a thin film structure composed of at least two materials with different thermal expansion coefficients, one end of the electrothermal MEMS torsion actuator is fixed, and the other end is connected to the movable unit 2, and the electrothermal MEMS torsion actuator is asymmetrically distributed along its center line 3. When the temperature of the electrothermal MEMS torsion actuator 1 changes, the electrothermal MEMS torsion actuator 1 rotates around the x-axis direction, thereby driving the movable unit 2 to rotate.

[0005] The center line 3 of the electrothermal MEMS torsion actuator is not perpendicular to the fixed end surface, and the slope of the center line 3 has no inflection point.

[0006] The electrothermal MEMS torsion actuator 1 is symmetrically mounted on both sides of the movable unit 2, and the electrothermal MEMS torsion actuator 1 is connected to the movable unit 2 by a flexible structure 4. The flexible structure may be a spring.

[0007] An electrothermal MEMS torsion actuator group includes two electrothermal MEMS torsion actuators 1, namely an electrothermal MEMS torsion actuator 1A and an electrothermal MEMS torsion actuator 1B. The electrothermal MEMS torsion actuator 1A and the electrothermal MEMS torsion actuator 1B are symmetrical, and the upper and lower orders of the two layers of thin film materials are opposite. One end of the electrothermal MEMS torsion actuator group is fixed, and the other end is connected to a movable unit 2.

[0008] The electrothermal MEMS torsion actuator 1 is composed of a three-layer film structure composed of at least two materials with different thermal expansion coefficients. One film B1 of the three-layer film structure is made into a continuous plane, and the other two films of the same material are respectively made on the upper and lower surfaces of the film B1 and are distributed on the left and right sides of the structure.

[0009] The electrothermal MEMS torsion actuator group is symmetrically installed on both sides of the movable unit 2 .

[0010] The invention has the advantages that the technical problem that the existing electrothermal MEMS driver is difficult to twist is solved, and the invention has the characteristics of simple structure and easy realization. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of an electrothermal MEMS torsion actuator in Example 1.

[0012] Figure 2 This is a schematic diagram of an electrothermal MEMS torsion actuator in Example 2.

[0013] Figure 3 This is a microscopic photograph of Example 2 in the laboratory.

[0014] Figure 4 Schematic diagram of the electrothermal MEMS torsion actuator group in Example 3.

[0015] Figure 5 This is a schematic diagram of an electrothermal MEMS torsion actuator group in Example 4.

[0016] Figure 6 This is a schematic diagram of an electrothermal MEMS torsion actuator group in Example 4.

[0017] In the figure, 1 is an electrothermal MEMS torsion actuator, 2 is a movable unit, 3 is a center line of the electrothermal MEMS torsion actuator, and 4 is a flexible structure. DETAILED DESCRIPTION

[0018] An electrothermal MEMS torsion actuator, characterized in that the electrothermal MEMS torsion actuator 1 is a thin film structure composed of at least two materials with different thermal expansion coefficients, one end of the electrothermal MEMS torsion actuator is fixed, and the other end is connected to a movable unit 2, and the electrothermal MEMS torsion actuator is asymmetrically distributed along its center line 3, usually forming a right triangle (such as Figure 2 As shown in FIG. 1 ). When the temperature of the electrothermal MEMS torsion actuator 1 changes, the electrothermal MEMS torsion actuator 1 rotates around the x-axis direction, thereby driving the movable unit 2 to rotate. The temperature change is provided by the metal resistor or polysilicon resistor in the thin film layer. The metal resistor materials commonly used are titanium, platinum and tungsten.

[0019] The center line 3 of the electrothermal MEMS torsion actuator is not perpendicular to the fixed end surface, and the slope of the center line 3 has no inflection point.

[0020] The electrothermal MEMS torsion actuator 1 is symmetrically mounted on both sides of the movable unit 2 , and the electrothermal MEMS torsion actuator 1 and the movable unit 2 are connected by a flexible structure 4 .

[0021] An electrothermal MEMS torsion actuator group includes two electrothermal MEMS torsion actuators 1, namely an electrothermal MEMS torsion actuator 1A and an electrothermal MEMS torsion actuator 1B. The electrothermal MEMS torsion actuator 1A and the electrothermal MEMS torsion actuator 1B are symmetrical, and the upper and lower orders of the two layers of thin film materials are opposite. One end of the electrothermal MEMS torsion actuator group is fixed, and the other end is connected to a movable unit 2.

[0022] The electrothermal MEMS torsion actuator 1 is composed of a three-layer film structure composed of at least two materials with different thermal expansion coefficients. One film B1 of the three-layer film structure is made into a continuous plane, and the other two films of the same material are respectively made on the upper and lower layers of the film B1 and are distributed on the left and right sides of the structure.

[0023] The electrothermal MEMS torsion actuator group is symmetrically installed on both sides of the movable unit 2 .

[0024] Example 1

[0025] like Figure 1 As shown, this example uses an electrothermal MEMS torsion actuator to drive the movable unit 2 to rotate, wherein the movable unit 2 is a MEMS micromirror. The electrothermal MEMS torsion actuator is composed of two layers of SiO2-Al thin film structures, and the electrothermal MEMS torsion actuator has a built-in heating resistor wire. The metal wire can be placed between the SiO2 and Al thin films, or on the surface of any two thin films. The electrothermal MEMS torsion actuator is divided into a number of rectangles with a length of Δx laterally, wherein the adjacent rectangles 1-1 and 1-2, when rectangles 1-1 or 1-2 are independent, the rectangular double-layer membrane structure (i.e., rectangle 1-1 or rectangle 1-2) warps to both sides, and the bending radius ρ can be expressed by formula 1, wherein β is a coefficient related to the Young's modulus of the material, t is the thickness of the double-layer membrane, and ε is the deformation difference of the two layers caused by thermal expansion.

[0026]

[0027] Since the electrothermal MEMS torsion actuator is asymmetrically distributed along its center line 3, an interaction force will be generated between rectangle 1-1 and rectangle 1-2, making the curvature of the two continuous. When the temperature rises, the electrothermal MEMS torsion actuator curls toward the material layer with a low thermal expansion coefficient and rotates around the x-axis. As a best embodiment, Figure 1 As shown, the center line 3 of the electrothermal MEMS torsion actuator is not perpendicular to the fixed end surface, and the slope of the center line 3 has no inflection point.

[0028] Example 2

[0029] like Figure 2 , Figure 3 As shown, as a variation of the first embodiment, in this embodiment, the electrothermal MEMS torsion actuator 1 is symmetrically installed on both sides of the movable unit 2, and the electrothermal MEMS torsion actuator and the movable unit 2 are connected by a flexible structure 4.

[0030] Example 3

[0031] like Figure 4 As shown, the electrothermal MEMS torsion actuator group includes two electrothermal MEMS torsion actuators 1, namely, electrothermal MEMS torsion actuator 1A and electrothermal MEMS torsion actuator 1B. The electrothermal MEMS torsion actuator 1A and the electrothermal MEMS torsion actuator 1B are symmetrical on the left and right, and the two layers of thin film materials are in opposite order from top to bottom. One end of the electrothermal MEMS torsion actuator group is fixed, and the other end is connected to the movable unit 2.

[0032] Example 4

[0033] like Figure 5 As shown, as a variation of Example 3, a three-layer thin film structure is formed by at least two materials with different thermal expansion coefficients, one of the thin films B1 (for example, SiO2) of the three-layer thin film structure is made into a continuous plane, and the other two thin films of the same material (for example, Al) are respectively made on the upper and lower layers of B1 (for example, SiO2), and the structure is symmetrical on the left and right.

[0034] Example 5

[0035] As a variation of the third embodiment, in this embodiment, the electrothermal MEMS torsion actuator groups are symmetrically installed on both sides of the movable unit 2, such as Figure 6 shown.

Claims

1. An electrothermal MEMS torsion actuator, characterized in that The electrothermal MEMS torsion actuator (1) comprises a thin film structure composed of at least two materials with different thermal expansion coefficients; one end of the electrothermal MEMS torsion actuator is fixed and the other end is connected to a movable unit (2); the electrothermal MEMS torsion actuator is asymmetrically distributed along its center line (3); when the temperature of the electrothermal MEMS torsion actuator (1) changes, the electrothermal MEMS torsion actuator (1) rotates around the x-axis direction, thereby driving the movable unit (2) to rotate; the center line (3) of the electrothermal MEMS torsion actuator is not perpendicular to the fixed end face, and the slope of the center line (3) has no inflection point.

2. The electrothermal MEMS torsion actuator according to claim 1, characterized in that The electrothermal MEMS torsion actuator (1) is symmetrically mounted on both sides of the movable unit (2), and the electrothermal MEMS torsion actuator (1) and the movable unit (2) are connected using a flexible structure (4).

3. The electrothermal MEMS torsion actuator according to claim 1, characterized in that One of the materials of the thin film structure is metal or polysilicon.

4. The electrothermal MEMS torsion actuator according to claim 1, characterized in that The two materials of the thin film structure with different thermal expansion coefficients are one material of SiO2 and the other material of metal aluminum Al.

5. An electrothermal MEMS torsion actuator assembly, characterized in that It comprises two electrothermal MEMS torsion actuators (1) as claimed in claim 1, wherein the two electrothermal MEMS torsion actuators are symmetrical, and the materials of the two-layer film structure are arranged in opposite order from top to bottom. One end of the electrothermal MEMS torsion actuator group is fixed, and the other end is connected to the movable unit (2).

6. The electrothermal MEMS torsion actuator assembly according to claim 5, characterized in that The electrothermal MEMS torsion actuator (1) comprises a three-layer thin film structure composed of at least two materials with different thermal expansion coefficients, wherein one thin film (B1) of the three-layer thin film structure is made into a continuous plane, and the other two thin films made of the same material are respectively made on the upper and lower surfaces of the film (B1) and are respectively distributed on the left and right sides of the structure.

7. The electrothermal MEMS torsion actuator assembly according to claim 5, characterized in that The electrothermal MEMS torsion actuator group is symmetrically mounted on both sides of the movable unit (2).

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