JP3942621B2 - Electrostatic drive type optical deflection element - Google Patents

Description

  The present invention relates to an electrostatic drive type optical deflection element, and more particularly to its low frequency drive, improvement of impact resistance, and cost reduction.

  A small-sized optical deflection element manufactured by MEMS (Micro Electro Mechanical Systems) technology can realize a reduction in size and cost of an optical deflection system. Therefore, various proposals have been made, and trial manufacture and practical use are proceeding. There are various types of devices such as an electrostatic drive system, an electromagnetic drive system, and other systems in terms of operation principle. For example, various optical deflection elements (also referred to as galvanometer mirrors) that operate on the principle of galvanometers (moving coil electromagnetic drive) have been proposed (Patent Document 1), and these optical deflection elements are MEMS that utilize semiconductor manufacturing technology. Manufactured with manufacturing technology.

  These optical deflecting elements are configured as a double-supported beam structure using silicon as a material for the double-supported beam 19 as shown in FIG. 9 (Patent Document 2). This is because the MEMS manufacturing technology based on the semiconductor manufacturing technology is excellent in silicon high-precision processing capability, and silicon, which is an elastic material, is suitable as a material for the cantilever beam 19.

  However, in recent years, there has been an increasing demand for realizing a small optical deflecting element that operates at a low driving frequency of, for example, 100 Hz or less, and for realizing an optical deflecting element having excellent impact resistance for portable device products at a low cost. Various problems have arisen in order to use as a material for a doubly supported beam. These problems will be described with reference to FIGS.

FIGS. 10 and 11 are diagrams for explaining the problem that miniaturization of the optical deflection element is restricted when low frequency deflection is realized by using silicon as a doubly supported beam material. Silicon has a large Young's modulus of about 130 GPa, and in order to operate at a low frequency of 100 Hz or less, it is necessary to design the cantilever beam 19 to be long, thin, and thin. It is considered that low-frequency driving can be realized by setting the width of the both-end supported beam 19 to 0.05 mm or less and the thickness of the both-end supported beam 19 to 0.01 mm or less. However, at this time, the optical deflecting element is limited in the miniaturization of the element due to the restriction due to the length of the doubly supported beam 19 as shown in FIG. In order to realize the miniaturization of the element, a method of designing by bending the doubly supported beam 19 as shown in FIG. 11 is conceivable. However, although silicon is a hard material having a Young's modulus of about 130 GPa, it is a brittle material, and long, thin and thin silicon doubly supported beams are fragile, causing problems in productivity and falling even when manufactured. Since the cantilever beam is damaged, it is not applicable to portable device products that require impact resistance. Further, since silicon is an expensive material and is processed by an expensive semiconductor manufacturing apparatus, there is a limit to cost reduction.
As described above, it is practically impossible to realize an optical deflecting element that can realize low-frequency driving at low cost by using silicon as a material for a double-supported beam.

As a technique for realizing an optical deflecting element capable of realizing low-frequency driving at a low cost, a technique using polyimide as a material for a doubly supported beam has been proposed (Patent Document 3). Since polyimide has a low Young's modulus of about several GPa and is not a brittle material like silicon, it can be expected to realize a small optical deflection element having a low driving frequency and excellent impact resistance. However, the Young's modulus of polyimide is about several GPa, and the control range is narrow, so there is a problem that design restrictions are large, such as low frequency driving.
JP 2002-228951 A Japanese Patent Application Laid-Open No. 07-175005 Japanese Patent Laying-Open No. 2005-099063

  Small-sized optical deflecting elements manufactured by MEMS (Micro Electro Mechanical Systems) technology can realize miniaturization and cost reduction of optical deflecting systems, and therefore various types are being developed and put into practical use. Many of these light deflection elements have a double-supported beam structure using single crystal silicon as a beam material, and a movable part having a mirror that reflects light is moved by electrostatic force or electromagnetic force to deflect light. It is said.

  However, there is a strong demand to realize a small optical deflection element with a low driving frequency and excellent impact resistance at low cost. The Young's modulus is as large as about 130 GPa. There were various problems such as being forced to become large and being unable to ensure sufficient impact resistance. In order to solve these problems, proposals have been made to use polyimide as a beam material, but there are still various problems such as a narrow Young's modulus control range and a limit to low-frequency driving.

  The present invention has been made under such circumstances, and it is an object of the present invention to provide a light deflection element that can be driven at a low frequency, has excellent impact resistance, and is small and low cost.

In order to solve the above-described problem, in the present invention, the electrostatic drive type optical deflection element is configured as described in (1 ) below.
(1) A soft resin part having a base part, a stationary part fixedly or continuously formed on the base part, and a movable part supported by the stationary part by a doubly supported beam part, the movable part having an electrode function And a reflecting plate fixed on the movable part, a fixed electrode disposed to face the movable part at a predetermined interval, and a fixed electrode substrate fixed to the pedestal component,
The electrostatic drive type optical deflection element, wherein the soft resin component is formed of conductive silicone rubber, and the fixed electrode of the fixed electrode substrate is divided into two.

  According to the present invention, since the silicone rubber, which is a soft and non-brittle material, can be applied to the material of the cantilever beam that supports the movable part to which the reflecting plate is fixed, it can be driven at a low driving frequency and has a small impact resistance. The electrostatic drive type optical deflection element can be provided.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to examples.

  1, 2 and 3 are diagrams showing a configuration of an “electrostatic drive type optical deflection element” according to the first embodiment, FIG. 1 is a top view of the electrostatic drive type optical deflection element, and FIGS. FIG. In addition, the peripheral part in the soft resin component 5 formed of silicone rubber is the stationary part 3, and the part that is supported by the stationary part 3 by the doubly supported beam 2 and to which the reflecting plate 6 is fixed is the movable part 1.

  The soft resin component 5 is fixed to the upper surface side of the manufactured pedestal component 14, the reflector 6 is fixed to the upper surface side of the soft resin component 5, and the fixed electrode component 11 is fixed to the lower surface side of the pedestal component 14. Thus, the electrostatic drive type optical deflection element shown in FIGS.

  The pedestal component 14 can be easily formed by molding silicone rubber by a molding technique. For example, the pedestal component 14 has a frame width of 1 mm, an outer frame having a side length of 5 mm, and a thickness of 0.3 mm. By mixing metal particles and carbon particles in the silicone rubber precursor before molding, the pedestal component is made conductive. The pedestal component 14 is preferably hard and less deformed, and the Young's modulus was controlled to be about 10 MPa by vulcanization control.

  In the first embodiment, silicone rubber is applied as a material for the pedestal component 14; however, a conductive plastic, a silicon substrate drilled by a semiconductor manufacturing technique, a ceramic substrate drilled by a sandblast technique, or the like may be used. In the first embodiment, the molding technique is applied as a method for molding the silicone rubber. However, the molding technique may be performed by a punching technique.

  The soft resin component 5 can be easily formed by molding silicone rubber by a molding technique, and has the same conductivity as the pedestal component 14. The soft resin component 5 is electrically connected. Further, the soft resin component 5 was controlled to have a Young's modulus of about 10 kPa by vulcanization control. In the first embodiment, the molding technique is applied as a method for molding the silicone rubber. However, the molding technique may be performed by a punching technique.

  The reflection plate 6 is obtained by depositing a gold film serving as the reflection film 12 on the glass substrate 13 having a thickness of 200 microns to a thickness of 1.0 microns by vapor deposition, and then cutting the glass substrate 13 to a desired size by a dicing technique. For example, it has a square shape with a side of 2 mm. In the first embodiment, the glass substrate 13 is used as the substrate of the reflection plate 6, but a silicon substrate or the like may be used.

  The fixed electrode component 11 can be formed by processing the silicon substrate 8 by a semiconductor manufacturing technique. For example, a desired resist pattern is formed on a silicon substrate 8 having a thickness of 600 microns by photolithography, and the silicon substrate 8 is etched to a depth of 2 microns with a mixed aqueous solution of hydrofluoric acid, nitric acid and acetic acid using the resist as an etching mask. After the step 10 of the silicon substrate is formed, a silicon oxide film 27 is formed to a thickness of 1 micron by thermal oxidation, and aluminum, gold, or the like that becomes the fixed electrode 7 is formed on the silicon oxide film 27 by a photolithography technique and an etching technique. The fixed electrode wiring 15 can be formed by patterning and cutting out to a desired size by a dicing technique, and may be, for example, 6 mm × 7 mm.

  In the first embodiment, the silicon substrate 8 is applied as the fixed electrode substrate, but a glass substrate or the like may be used. In addition, the fixed electrode component can be easily realized by an existing flexible substrate manufacturing technology made of polyimide or the like.

  In the first embodiment, the pedestal component 14 and the soft resin component 5 are formed separately, but may be formed continuously using a plurality of molds.

  The soft resin component 5 is fixed to the upper surface side of the pedestal component 14 with a conductive adhesive 17, the reflector 6 is fixed to the upper surface side of the soft resin component 5, and the lower surface side of the pedestal component 14 is In the element constituted by fixing the fixed electrode component 11, for example, when the movable electrode pad 4 of the conductive soft resin component 5 is fixed to the ground potential, the element is formed via the pedestal component 14 formed of conductive silicone rubber. Thus, the soft resin component 5 having the movable part 1 can be fixed to the ground potential. Since the movable part 1 of the soft resin component 5 has conductivity, it has a function as a movable electrode.

  Here, a low frequency AC voltage is applied to one side of the pair of fixed electrodes formed on the fixed electrode component 11, for example, 7-1 via the fixed electrode pad 9-1 (that is, the fixed electrode pad 9-1 and the movable electrode). When a low frequency AC voltage is applied between the pads 4), electrostatic attraction is periodically generated between the movable part 1 of the soft resin component 5 and the fixed electrode 7-1 on the one side to which the voltage is applied. Combined with the elastic force of the both-end supported beam 2, the movable portion 1 of the soft resin component 5 rotates in both directions around the both-end supported beam 2, and the reflector 6 fixed to the soft resin component 5 is moved. It can be rotated and the reflected light can be periodically deflected by the reflecting plate 6.

  Further, when a DC voltage is applied to one side of the pair of fixed electrodes 7, for example, 7-1 via the fixed electrode pad 9-1, the movable part 1 of the soft resin component 5 and the fixed electrode on the one side to which the voltage is applied 7-1, an electrostatic attractive force is continuously generated, and the movable portion 1 rotates in one direction around the both-end supported beam 2 and is fixed to the soft resin component 5 6 is rotated, and the reflected light can be continuously deflected in one direction by the reflecting plate 6. When a DC voltage is applied to the other fixed electrode 7-2 via the fixed electrode pad 9-2, the movable part 1 of the soft resin component 5 and the fixed electrode 7-2 on one side to which the voltage is applied are applied. In the meantime, electrostatic attraction is continuously generated, the movable part 1 rotates in the other direction around the both-end supported beam 2, and the reflecting plate 6 fixed to the soft resin component 5 rotates. The reflected light can be continuously deflected in the other direction by the reflecting plate 6.

The voltage applied to the fixed electrode is not limited to alternating current and direct current, but may be a pulse voltage.
In this manner, the electrostatic drive type optical deflection element of the first embodiment is driven.

  In the first embodiment, the fixed electrode is divided into two with the double-supported beam 2 as the center. However, the present invention is not limited to this, and the movable electrode is divided into two, or both the fixed electrode and the movable electrode are divided into two. Can be implemented.

  According to the first embodiment, since the soft and non-brittle silicone rubber can be applied to the doubly supported beam material, it is possible to easily realize an optical deflection element that can be driven at a low frequency and has excellent impact resistance. In addition, since an inexpensive silicone rubber material can be used as a base material and can be formed by a low-cost processing technique such as a molding technique or a punching technique, an inexpensive optical deflection element can be provided.

  Further, as is well known, a rubber material such as silicone rubber can control its Young's modulus over a wide range from about 1 kPa to about 10 MPa by controlling the ratio of sulfur contained therein, and thus, for example, the sulfur content is controlled. Since it is possible to change the resonance frequency of the system without changing the geometric design of the parts, it is possible to reduce the cost for creating photomasks and molds and shorten the product development period.

  The soft resin component 5 can be made insulative and the movable electrode can be fixed to the surface. In this case, it is necessary to connect the movable electrode pad and the movable electrode by an appropriate means.

  FIGS. 5 to 8 are diagrams showing the configuration of the “electrostatic drive type optical deflection element” according to the second embodiment, FIG. 5 is a top view of the electrostatic drive type optical deflection element, and FIGS. FIG. The reflector 6, the soft resin component 5, the pedestal component 14, and the fixed electrode component 11 are each provided with fixing positioning irregularities 28.

  The holes formed in the reflector 6 can be easily realized by applying a sandblasting technique or a laser processing technique to the reflector 6 formed by the same method as in the first embodiment.

  The pedestal component 14 and the soft resin component 5 are formed by molding silicone rubber by a molding technique in the same manner as in the first embodiment, and a hole formed in the reflector 6 on the upper surface side of the soft resin component 5. A protrusion is formed at a position corresponding to (see FIG. 8). A protrusion is formed on the bottom surface side of the pedestal component 14 at a position corresponding to a recess formed on the upper surface side of the fixed electrode component 11 (see FIG. 7).

  The recess formed in the fixed electrode part 11 can be easily formed by applying a sandblasting technique or a laser processing technique to the fixed electrode part formed by the same method as in the first embodiment.

  According to the second embodiment, when the reflecting plate 6 and the soft resin component 5 and the pedestal component 14 and the fixed electrode component 11 are fixed, the positioning unevenness 28 can be used. It is possible to reduce the performance variation of the deflection element. Although not shown in the second embodiment, it is possible to form an electrostatic drive type optical deflecting element that can further reduce the performance variation by forming the same positioning unevenness 28 in the fixing portion of the base component 14 and the soft resin component 5. Not too long.

  As described above, according to this embodiment, silicone rubber, which is a soft and non-brittle material, can be applied to the material of the cantilever beam that supports the movable part to which the reflector plate is fixed, so that it is driven at a low driving frequency. It is possible to provide a small electrostatically driven optical deflecting element that is excellent in impact resistance.

  In addition, since an inexpensive material such as silicone rubber is used as a base material and an inexpensive process such as molding technology or punching technology can be used, a low-cost electrostatically driven optical deflection element can be easily realized.

  Moreover, since the positioning irregularities can be used, the fixing alignment accuracy can be improved, and the performance variation of the optical deflection element can be reduced.

The top view which shows the structure of Example 1 AA sectional view showing the composition of Example 1 BB sectional view showing the configuration of Example 1 CC sectional drawing which shows the structure of Example 1. FIG. The top view which shows the structure of Example 2 DD sectional drawing which shows the structure of Example 2. EE sectional drawing which shows the structure of Example 2. FF sectional drawing which shows the structure of Example 2. Top view showing the configuration of a conventional optical deflection element Top view showing the configuration of a conventional optical deflection element Top view showing the configuration of a conventional optical deflection element

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Movable part 2 Both-ends beam part 3 Non-moving part 5 Soft resin component 6 Reflector 7-1 Fixed electrode 7-2 Fixed electrode 14 Base component

Claims (1)

A pedestal component, a non-moving portion fixed or continuously formed on the pedestal component, and a movable portion supported by the non-moving portion by a doubly supported beam portion, and the movable portion having an electrode function; a reflector secured on the movable portion, the fixed electrode facing each provided with a predetermined interval with respect to the movable portion, and a fixed electrode substrate which is secured to the pedestal part,
2. The electrostatic drive type optical deflection element according to claim 1, wherein the soft resin component is made of conductive silicone rubber, and the fixed electrode of the fixed electrode substrate is divided into two .

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