KR100452113B1 - Micromirror device using cantilever - Google Patents

Abstract

A micromirror device according to the present invention comprises: a substrate on which an addressing circuit is configured; Two electrodes formed on the substrate to face each other with respect to the center of the substrate and electrically connected to the addressing circuit; A cantilever support formed perpendicular to the center of the substrate and electrically connected to the addressing circuit; Two cantilever beams which are horizontally supported by the cantilever support and each extend in both sides to be point symmetrical with respect to the part where the cantilever support meets; Mirror supports vertically formed on each end of the cantilever beam; A mirror placed horizontally on the mirror support; And the cantilever beam is deformed by the electrostatic force between the electrode and the cantilever generated by the addressing circuit or by the electrostatic force between the electrode and the mirror to rotate the mirror to reflect the light path by the mirror. It is characterized by changing. According to the present invention, the length of the cantilever that can be deformed compared to the prior art is very long, and various types of spring structures can be applied to bend more at low voltages.

Description

Micromirror device using cantilever}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a micromirror device, and more particularly, to a micromirror device that changes a light propagation path by adjusting a reflection angle of incident light by rotating a mirror by electrostatic force.

Representative image display micromirror devices are arranged two-dimensionally on a substrate on which addressing circuitry is fabricated, and are driven by electrostatic force to reflect incident light at a predetermined angle. Such a micromirror device can be utilized for optical information processing, projection displays, video and graphics monitors, image display devices such as televisions, and optical scanning devices such as copiers.

1 to 3 are diagrams for explaining a conventional image display micromirror device disclosed in US Patent No. 5,535,047 issued to Hornbeck on July 9, 1996.

1 is a schematic exploded perspective view of a micromirror device. Referring to FIG. 1, there is a layer having a yoke address electrode 10 and a landing site 11 formed on an addressing circuit (not shown), supported by an address support 12 thereon, and a mirror address electrode 13. ), A torsion hinge 14, and a yoke 15 directly connected to the mirror 17. On top of that lies a mirror 17 which is also connected to the yoke 15 by a mirror support 16. The conventional micromirror device is composed of four layers including a mirror and an addressing circuit, and includes an address support 12 supporting a mirror address electrode layer, a mirror support 16 supporting a mirror, and a mirror 17. And yoke 15 connected to the torsional hinge 14 and one yoke address electrode 10 for applying a voltage between the mirror 17 and the mirror address electrode 12 for driving the mirror 17. ) It consists of two.

2 is a cross-sectional view of the micro device of FIG. 1 viewed in the hinge 14 direction. 2, the mirror 17 is connected to the yoke 15 by a mirror support 16, and a hinge 14 is installed below the yoke 15 to serve as a rotating shaft. The yoke address electrode 10 is connected to the address support 12, and is also connected to the substrate 6 partially covered by the protective oxide film 8 after being processed to form an addressing circuit.

3 is a cross-sectional view seen from the vertical direction of the hinge 14 in which the mirror 17 rotates when a voltage is applied between the mirror 17 and the mirror address electrode 13. Reference numerals of components that are not related to the description of the technical contents are omitted here. When a potential difference occurs between the mirror 17 and one electrode 10, the mirror 17 is rotated in one direction as shown in FIG. 3A by an electrostatic force, and after being rotated at a predetermined angle, the mirror 17 is no longer hit by the landing site 11. I can't turn and stop. On the other hand, when a voltage is applied between the other electrode 10 and the mirror 17, it is rotated in another direction as shown in FIG. The mirror 17 has two stable states as described above, and the angle at which light incident on the mirror is reflected varies depending on two rotation states of the mirror. Therefore, by changing the traveling path of the light incident from a certain direction to the mirror 17, the light can be incident on or off the lens (not shown) and the screen (not shown).

As described above, the conventional micromirror device is composed of a mirror 17 and the yoke 15, the hinge 14, the support 12, 16, each of which is complicated in structure and has to go through various processes in manufacturing. There is this. Therefore, due to such a complicated structure, it is difficult to constantly drive the mirror 17, the manufacturing process is difficult and the manufacturing cost is expensive.

In addition, in the conventional micromirror device, the mirror address electrode 13 is provided with an appropriate voltage so that the mirror 17 is always rotated in both the left and right directions so that the hinge 14 is in a twisted state. This operation is done by a pair of thin hinges 14 so that the firmness of the hinges 14 is a major factor in determining the characteristics of the device.

Accordingly, a technical object of the present invention is to provide a micromirror device for changing the rotation angle of a mirror by a simple method using a cantilever.

1 to 3 are diagrams for explaining a conventional micromirror device for image display;

4 to 8 are views for explaining a micromirror device according to a first embodiment of the present invention;

9 is a view for explaining a micromirror device according to a second embodiment of the present invention;

10 is a view for explaining a micromirror device according to a third embodiment of the present invention;

11 is a view for explaining a micromirror device according to a fourth embodiment of the present invention;

12 is a view for explaining the spring structure of the second embodiment and the fourth embodiment in more detail.

<Description of Reference Numbers for Main Parts of Drawings>

20: mirror 21: substrate

22. 23, 52, 53: electrode 24: cantilever support

26, 27: mirror support 37: lens

31, 32, 31 ', 32', 41, 42, 41 ', 42': cantilever

According to another aspect of the present invention, there is provided a micromirror device comprising: a substrate on which an addressing circuit is configured; Two electrodes formed on the substrate to face each other with respect to the center of the substrate and electrically connected to the addressing circuit; A cantilever support formed perpendicular to the center of the substrate and electrically connected to the addressing circuit; It is horizontally supported by the cantilever support and extends to both sides so as to be point symmetrical with respect to the part where it meets the cantilever support, and the extension is stopped at the upper portion of the electrode, and a predetermined portion has a spring structure, and the end portion has a spring structure. Two cantilever beams having a plate shape extended two-dimensionally to have a larger area; Mirror supports vertically formed on each end of the cantilever beam; A mirror placed horizontally on the mirror support; And the cantilever beam is deformed by the electrostatic force between the electrode and the cantilever generated by the addressing circuit or by the electrostatic force between the electrode and the mirror to rotate the mirror to reflect the light path by the mirror. It is characterized by changing.

As the material of the cantilever, polycrystalline silicon or a metal doped with a dopant may be used. This is because the cantilever must be a conductive material in order to apply an electrostatic force between the electrode and the cantilever. The mirror may also be made of doped polycrystalline silicon or metal, and a thin metal layer having high reflectivity, such as aluminum, gold, or silver, may be coated on the mirror surface in one layer, double, or triple to increase the reflectivity of the mirror.

The spring structure may be twisted alternately in the horizontal and vertical directions, or may be twisted in the vertical direction.

On the other hand, the substrate has a rectangular shape; The electrodes are installed in a triangle shape at two opposite vertex portions of the substrate, the vertices and sides of which are coincident with the vertices and sides of the substrate; Each of the cantilever beams extends linearly to the top of the vertex of the substrate where no electrode is formed at a portion where the cantilever support meets, and then is bent in the direction in which the electrodes are extended to the top of the electrode, and the ends are the same as those of the electrode. It may be in the form of a triangle of size.

On the other hand, the substrate has a rectangular shape; The electrode is installed in a square shape at two opposite vertex portions of the substrate, the vertices and sides of which are coincident with the vertices and sides of the substrate; Each of the cantilever beams is bent back to the upper edge of the substrate where the electrode is not formed after the substrate extends in a straight line to the upper side at the portion meeting with the cantilever support, and then bent back toward the vertex direction of the substrate on which the electrode is formed. Extending to the top and the end may be in the form of a square of the same shape and size as the electrode.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail. In the drawings, like reference numerals denote components that perform the same function, and repetitive description thereof will be omitted.

Example 1

4 to 8 are diagrams for describing a micromirror device according to a first embodiment of the present invention.

4 is a schematic exploded perspective view of the micromirror device according to the present invention, FIG. 5 is a plan view of the cantilever 31 and 32, and FIG. 6 is a side view of FIG. 4 seen from the a-a 'direction of FIG.

4 to 6, an addressing circuit (not shown) is formed on a rectangular substrate 21, and electrodes 22 and 23 are formed on the substrate 21 to be electrically connected to the addressing circuit. do. The electrodes 22 and 23 are formed at two vertex portions facing the substrate 21 so as to face each other with respect to the center of the substrate 21. The electrodes 22 and 23 have a triangular shape and their vertices and sides are installed to coincide with the vertices and sides of the substrate 21.

The cantilever support 24 is vertically installed at the center of the substrate 21. The cantilever support 24 is made of a conductive material and electrically connected to the address circuit of the substrate 21 so that voltage can be applied to the cantilever beams 31 and 32 connected to the cantilever support 24.

The cantilever beams 31 and 32 are horizontally supported by the cantilever beam 24 and extend in both sides to be point symmetrical with respect to the portion where the cantilever beam 24 meets. The two cantilever beams 31 and 32 are formed in one piece.

Each cantilever 31, 32 is divided into three parts. The first portions 31a and 32a extend in a straight line to the upper edge of the substrate 21 where the electrodes 22 and 23 are not formed at the portion where the cantilever support 24 meets the second portion 31b, 32b) is a portion bent in the direction in which the electrodes 22, 23 are located at the ends of the first portions 31a, 32a. The third portions 31c and 32c are connected to the ends of the second portions 31b and 32b and are positioned on the electrodes 22 and 23 and have a triangular shape having the same shape and size as the electrodes 22 and 23. Part.

Mirror supports 26 and 27 are vertically installed on the third portions 31c and 32c of the cantilever beam, and the mirror 20 is horizontally placed on the mirror supports 26 and 27.

7 is a view for explaining a driving state of the micromirror device according to the first embodiment. Referring to FIG. 7, when the voltage difference occurs between the right electrode 22 and the corresponding cantilever 32, the cantilever 32 is bent by the electrostatic force that is attracted so that the mirror 20 rotates to the right. Therefore, the light reflected by the mirror 20 does not pass through the lens 37 and becomes dark. When a voltage difference occurs between the left electrode 23 and the corresponding cantilever 31, the cantilever 31 is also bent by the electrostatic force, and the mirror 20 is rotated to the left. Therefore, the light reflected by the mirror 20 passes through the lens 37 and becomes bright. As such, when using the micromirror device according to the present invention, the dark state and the bright state are determined by the rotation of the mirror 20.

This is suitable when the micromirror device according to the present invention is typically used for image display, and the degree of deflection of the cantilever can be determined by the voltage difference with the electrode so that the rotation angle of the mirror can be continuously adjusted by the address voltage. The lower surface can also be used in fields such as optical switching using the rotation of the mirror.

Since the electrostatic force should be generated between the cantilever 31 and 32 serving as the driving layer and the electrodes 22 and 23, the cantilever 31 and 32 should be made of a flexible and conductive material. As such a material, polycrystalline silicon or metal to which a dopant is added can be used. Of course, the cantilever beams 31 and 32 may be bent by the electrostatic force between the mirror 20 and the electrodes 22 and 23 by making the mirror 20 a conductive material. In this case, the mirror 20 may be made entirely of metal, or may be made of metal on the surface of polycrystalline silicon. At this time, the metal coating is preferably made so that the reflectance is high.

The reason for making the third portions 31c and 32c of the cantilever into a plate shape extended two-dimensionally to have a larger area than other portions is to allow the electrostatic force to work more strongly.

FIG. 8 is a diagram illustrating a case where a two-dimensional array is manufactured using the micromirror device according to the first embodiment. In this configuration, one micromirror device may serve as one pixel in an image display system, and thus may be applied as a projection display. When the image display system is configured using such a micromirror device, it is inexpensive, high definition, and light utilization efficiency is higher than that of a conventional liquid crystal display device.

Example 2

9 is a view for explaining a micromirror device according to a second embodiment of the present invention. 9, it is different from the first embodiment that the second portions 31b 'and 32b' of the cantilever have a spring structure. According to such a configuration, since the second portions 31b 'and 32b' are substantially longer than in the case of the first embodiment, a larger displacement can be driven at a lower address voltage.

Example 3

10 is a view for explaining a micromirror device according to a third embodiment of the present invention. Referring to FIG. 10, the electrodes 52 and 53 have a quadrangular shape so as to correspond to the vertices and sides of the vertex and sides of the substrate 21, and the cantilever 41 and 42 are each divided into four parts. It is different from the example.

The first portions 41a and 42a extend in a straight line from the portion that meets the cantilever support 24 to the upper side of the substrate 21, and the second portions 41b and 42b are the first portions 41a and 42a. Is a portion bent from the end of the substrate to the top of the vertex of the substrate is not formed, the third portion (41c, 42c) is the electrode (52, 53) at the end of the second portion (41b, 42b) This is the part bent in the direction. In addition, the fourth portions 41d and 42d are connected to the ends of the third portions 41c and 42c and are positioned on the electrodes 52 and 53, respectively, and have a quadrangular shape having the same shape and size as the electrodes 52 and 53. Part.

According to the third embodiment, the length of the cantilever 41 and 42 is longer than that of the first embodiment, thereby enabling more driving.

Example 4

11 is a view for explaining a micromirror device according to a fourth embodiment of the present invention. Referring to Fig. 11, it is different from the third embodiment that the third portions 41c 'and 42c' of the cantilever have a spring structure. According to such a configuration, since the third portions 41c 'and 42c' are substantially longer than those of the third embodiment, a larger displacement can be driven.

12 is a view for explaining the spring structure mentioned in the second and fourth embodiments in more detail. FIG. 12A illustrates a case in which the cantilever is straight, FIG. 12B illustrates a case where the cantilever is twisted only in the horizontal direction, and FIG. 12C illustrates a case where the cantilever is twisted only in the vertical direction. And, Figure 12d is a case of twisted form alternately in the horizontal direction and the vertical direction.

When the cantilever is twisted only in the horizontal direction, the space below the mirror 20 is too narrow to install the cantilever, which is not preferable, and even if installed, there is a possibility that it may protrude out of the mirror 20. In this case, there may be a fatal problem that is far from the next device. When the cantilever is twisted in the vertical direction, a much longer cantilever can be obtained because the remaining vertical space under the mirror 20 can be utilized. These may be combined to form a twisted shape alternately in the horizontal and vertical directions.

As described above, according to the present invention, the device has two stable rotation states because the device is very simple in structure and symmetrical form. In addition, since the driving force is wide, it can be driven with a small voltage. In addition, compared to the prior art, the cantilever can be deformed to be very long and bend more by applying various types of spring structures. In particular, by applying a spring structure twisted in the vertical direction to the cantilever beam can be driven more by utilizing the remaining vertical space under the mirror.

The present invention is not limited to the above embodiments, and it is apparent that many modifications are possible by those skilled in the art within the technical spirit of the present invention.

Claims (17)

A substrate on which an addressing circuit is configured; Two electrodes formed on the substrate to face each other with respect to the center of the substrate and electrically connected to the addressing circuit; A cantilever support formed perpendicular to the center of the substrate and electrically connected to the addressing circuit; It is horizontally supported by the cantilever support and extends to both sides so as to be point symmetrical with respect to the part where it meets the cantilever support, and the extension is stopped at the upper portion of the electrode, and a predetermined portion has a spring structure, and the end portion has a spring structure. Two cantilever beams having a plate shape extended two-dimensionally to have a larger area; Mirror supports vertically formed on each end of the cantilever beam; And A mirror placed horizontally on the mirror support; With The cantilever is deformed by the electrostatic force between the electrode and the cantilever generated by the addressing circuit or by the electrostatic force between the electrode and the mirror, thereby rotating the mirror to change a reflection path of light by the mirror. Micromirror device. 2. The micromirror device according to claim 1, wherein the cantilever is made of polycrystalline silicon or metal doped with dopant. The micromirror device according to claim 1, wherein the mirror is made of metal. 4. The micromirror device according to claim 3, wherein the mirror is made of polysilicon inside. delete The micromirror device according to claim 1, wherein the spring structure has a twisted shape alternately in a horizontal direction and a vertical direction. The micromirror device according to claim 1, wherein the spring structure is twisted in a vertical direction. delete The micromirror device according to claim 1, wherein the electrode and the cantilever tip have the same shape and size. The method of claim 1, wherein the substrate has a rectangular shape; The electrodes are installed in a triangle shape at two opposite vertex portions of the substrate, the vertices and sides of which are coincident with the vertices and sides of the substrate; Each of the cantilever beams extends linearly to the top of the vertex of the substrate where no electrode is formed at a portion where the cantilever support meets, and then is bent in the direction in which the electrodes are extended to the top of the electrode, and the ends are the same as those of the electrode. Micromirror device characterized in that the triangular shape of size. The micromirror device according to claim 10, wherein the cantilever portion bent in a direction in which the electrode is located above the vertex of the substrate on which the electrode is not formed has a spring structure. 12. The micromirror device according to claim 11, wherein the spring structure is twisted alternately in a horizontal direction and a vertical direction. The micromirror device according to claim 11, wherein the spring structure is twisted in a vertical direction. The method of claim 1, wherein the substrate has a rectangular shape; The electrode is installed in a square shape at two opposite vertex portions of the substrate, the vertices and sides of which are coincident with the vertices and sides of the substrate; Each of the cantilever beams is bent back to the upper edge of the substrate where the electrode is not formed after the substrate extends in a straight line to the upper side at the portion meeting with the cantilever support, and then bent back toward the vertex direction of the substrate on which the electrode is formed. Micromirror device, characterized in that extending to the top and the end is in the form of a square of the same shape and size as the electrode. 15. The micromirror device according to claim 14, wherein the cantilever portion bent in a vertex direction of the substrate on which the electrode is formed on the vertex of the substrate on which the electrode is not formed has a spring structure. 15. The micromirror device according to claim 14, wherein the spring structure is twisted alternately in a horizontal direction and a vertical direction. The micromirror device according to claim 14, wherein the spring structure is twisted in a vertical direction.