JP2003295074A - Light modulator - Google Patents

Abstract

(57) Abstract: Provided is an optical modulation device capable of suppressing an increase in a potential difference between a light reflecting member and a counter electrode, and also suppressing sticking of the two. SOLUTION: A light reflecting member 1 for reflecting incident light L from a light source on a front surface, a counter electrode layer 23 facing a back surface of the light reflecting member 1 via a gap G, and a substrate 2 supporting the light reflecting member 1
0, the light that changes the reflection direction of the incident light L by bending the light reflecting member 1 toward the counter electrode 1 with the inner edge E of the substrate as a support axis due to the potential difference between the light reflecting member 1 and the counter electrode layer 23. In the modulation device, the first opposing electrode portion 2 is provided on the opposing electrode layer 23.
2a, and a second counter electrode portion 23b disposed closer to the inner edge E of the substrate and the light reflecting member 1 than this.
The configuration is such that the potential difference between the second counter electrode 23b and the light reflecting member 1 and the potential difference between the first counter electrode 23a and the light reflecting member 1 can be individually set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information processing apparatus for processing optical information, an electrophotographic image forming apparatus for forming an image by performing optical writing based on image information on a latent image carrier, The present invention relates to a light modulator used for an image projection display device that projects and displays an image.

[0002]

2. Description of the Related Art Conventionally, in this type of optical modulator, an optical switch device utilizing electrostatic force is used to change the reflection direction of incident light to perform optical modulation.
In this optical switch device, a potential difference is generated between a light reflecting member that reflects incident light and a counter electrode that is arranged to face the light reflecting member, and the light reflecting member is bent toward the counter electrode.
Change the reflection direction of incident light. As a light modulation device that changes the reflection direction of incident light in this way, a cantilever support system in which a light reflection member that is cantilevered is bent at the free end side is known (for example, Non-Patent Document 1). etc).

[0003]

[Non-Patent Document 1] Applied Physics L
etters, Vol. 31, No. 8, pp521
pp523

[0004]

In the light modulating device, it is desirable to bend the light reflecting member with the potential difference as small as possible. However, it is conceivable that some kind of improvement may lead to a situation in which the need for increasing the potential difference is urged. In fact, the inventors of the present invention were forced to increase the potential difference while developing a new optical modulator called a double-support type. This light modulator is different from the conventional cantilever support method in which the free end side (the side opposite to the support end) of the light reflecting member supported in a cantilevered manner is bent, unlike the conventional light receiving member supported in both sides. It is equipped with a new structure that bends the central part. In the double-ended support system,
In addition to the force for bending the light reflection member so that it bends around the support portion as a spindle, a force for slightly expanding the light reflection member is also required. Therefore, a larger potential difference than that of the cantilever support method is required. Even if the cantilever support method is used, if the light reflecting member is formed thicker or a material having higher rigidity is used for the light reflecting member for some improvement, the potential difference is naturally increased accordingly. Need to increase.

Therefore, the inventors of the present invention have conducted extensive studies to suppress the increase in potential difference as much as possible, and as a result, have found a configuration as shown in FIG. In the figure, the light reflection member 1 that reflects the incident light L is supported on both sides by a substrate 20 as a support member. The cross-sectional shape of the substrate 20 is V-shaped as shown in the drawing, and a gap G is formed between the light-reflecting member 1 and the substrate upper surface region corresponding to the V-shaped valley. The substrate 20 has a counter electrode 22 laminated on the base layer 21, and its cross-sectional shape is also V-shaped. Such a V-shaped counter electrode 22 is closer to the light reflecting member 1 on both end sides than the conventional flat electrode. Even if the central portion of the light reflecting member 1 is largely bent to the contact position with the counter electrode 22, the end side portion of the light reflecting member 1 is not greatly bent. This is because the end side portion is near the bending support shaft. Therefore, even if the counter electrode 22 has a V-shaped cross-sectional shape as shown in the drawing, the support member 1 can be sufficiently bent toward the substrate 20. In such a configuration, the opposite electrodes 22 have both end sides closer to the light reflecting member 1 than the central portion, so that an electrostatic force larger than that of the conventional flat electrode is applied to the light reflecting member 1. And this can suppress increase in the potential difference.

In FIG. 1, an example of a double-supported support system is shown. In the cantilevered support system, a flat counter electrode, which is the same as the conventional one, is used, and a gap between this and the light reflection member 1 is provided at a support end. From the side to the free end side,
The opposing electrodes may be arranged diagonally. The configuration is only the left half or the right half of the V-shaped cross-sectional shape in FIG.

By the way, the inventors of the present invention prototyped an optical modulator having the structure shown in FIG. 1 and performed a test operation. As a result, the vicinity of both ends of the counter electrode 22 and the light reflecting member 1 were gradually fixed. It caused the problem of going.
Since both ends of the counter electrode 22 are close to the light reflecting member 1, they can be brought into close contact with the light reflecting member 1 with a stronger force than before. It is considered that this causes the adhesion between the light reflecting member 1 and both ends of the counter electrode 22. Further, the bending support shaft side of the light reflecting member 1 (fixed end sides of both ends)
It is considered that one of the factors that caused the above-mentioned sticking is that the restoring force is weak and it is difficult to separate from the closely attached counter electrode 22 due to the smaller bending amount than the central side.

The present inventors have also found that, if sticking occurs near both ends of the counter electrode 22, it gradually progresses toward the central valley side. This is considered to be due to the reason explained below. That is, when the light transmissive member 1 is fixed to both ends of the counter electrode 22, the fixed portion remains slightly bent even when the driving is stopped. Then, under the influence of this, a slight bend is formed around the fixed portion to form an inclination toward the counter electrode 22. In a humid environment, moisture condensed on the back surface of the light reflecting member 1 moves along the slope between the back surface and the counter electrode 22 to bridge them. The water bridge makes it difficult for the light reflecting member 1 and the counter electrode 22 to separate from each other around the already fixed portion, and the light reflecting member 1 and the counter electrode 22 are fixed to each other soon. In this way, the fixation gradually progresses toward the V-shaped valley. Therefore, how to suppress the fixing of the light reflecting member 1 to the counter electrode 22 that occurs first on the support shaft side is an important factor for ensuring good light modulation performance for a long period of time.

The present invention has been made in view of the above background, and it is an object of the present invention to suppress the increase in the potential difference between the light reflecting member and the counter electrode and also to prevent the two from sticking to each other. An optical modulator is provided.

[0010]

In order to achieve the above object, the invention of claim 1 provides a light reflecting member for reflecting light from a light source on a front surface and a gap on the back surface of the light reflecting member. A counter electrode facing each other, a potential difference generating means for generating a potential difference between them, and a support member for supporting the light reflection member, and the portion supported by the support member due to the potential difference serves as a spindle. In a light modulator for bending the light reflecting member toward the counter electrode to change the reflection direction of the light, the counter electrode is closer to the first counter electrode than the first counter electrode and the spindle and the light reflecting member. A second counter electrode disposed at a position, a second potential difference that is a potential difference between the second counter electrode and the light reflecting member, and a potential difference between the first counter electrode and the light reflecting member. In order to be able to set 1 potential difference and each separately, It is characterized in that to constitute a position difference generating means. The invention of claim 2 is the same as claim 1
In the light modulator of, a plurality of the light reflection members are provided,
It is characterized in that these are bent by the common first counter electrode and second counter electrode.
According to a third aspect of the present invention, in the optical modulation device according to the first or second aspect, the first counter electrode and the second counter electrode have an end shape that meshes in a wedge shape while maintaining an insulated state from each other. It is a feature. According to a fourth aspect of the present invention, in the optical modulator of the first, second or third aspect, the supporting member is configured to support both ends of the light reflecting member, and the two above-mentioned two members respectively generated at both ends. Two potential counter electrodes corresponding to the support shaft are provided, and the potential difference generating means is configured to generate the same second potential difference for each of the second counter electrodes. Further, the invention of claim 5 is the optical modulator according to claim 1, 2, 3 or 4, wherein the potential difference generating means includes the second potential difference varying means. The invention according to claim 6 is the optical modulator according to any one of claims 1, 2, 3, 4 or 5, wherein the variable means is in contact with the second counter electrode due to bending. It is characterized in that the second potential difference is changed with a minimum value required for maintaining contact with the member as a lower limit. The invention according to claim 7 is the optical modulator according to claim 5, characterized in that the variable means changes the second potential difference to a smaller value after a predetermined time has elapsed from the start of its generation. is there. Further, the invention of claim 8 is a light reflecting member for reflecting light from a light source on a front surface, a light reflecting member electrode fixed to the light reflecting member, and a counter electrode facing the back surface of the light reflecting member with a gap. A supporting member that supports the light reflecting member, and a potential difference generating unit that generates a potential difference between the light reflecting member electrode and the counter electrode, and a portion supported by the supporting member by the potential difference. In a light modulation device that changes the light reflection direction by bending the light reflection member toward the counter electrode side using a support axis, in the light reflection member electrode, the light reflection member first electrode and the support A light reflecting member second electrode for causing the potential difference at a position close to the axis, and the light reflecting member second electrode is provided.
The counter electrode region facing the electrode is located closer than the counter electrode region facing the light reflecting member first electrode, and the potential difference between the counter electrode and the light reflecting member second electrode and the counter electrode. And the potential difference generating means is configured so that the potential difference between the first counter electrode and the first counter electrode can be individually set. The invention of claim 9 is
A light reflecting member that reflects the light from the light source on the front surface, and a counter electrode that faces the back surface of the light reflecting member with a gap therebetween,
An electric potential difference generating means for generating an electric potential difference between the both and a supporting member for supporting the light reflecting member are provided, and the electric potential difference causes the portion supported by the supporting member to be a spindle and the light reflecting member for the counter electrode. In the light modulation device that bends the light toward the side and changes the reflection direction of the light, the counter electrode is arranged so as to gradually approach from the location side where the deflection amount of the light reflection member is maximum toward the spindle side. And a plurality of irregularities are provided on a surface of the counter electrode facing the light reflecting member. The invention of claim 10 is
A light reflecting member that reflects the light from the light source on the front surface, and a counter electrode that faces the back surface of the light reflecting member with a gap therebetween,
An electric potential difference generating means for generating an electric potential difference between the both and a supporting member for supporting the light reflecting member are provided, and the electric potential difference causes the portion supported by the supporting member to be a spindle and the light reflecting member for the counter electrode. In the light modulation device that bends the light toward the side and changes the reflection direction of the light, the counter electrode is arranged so as to gradually approach from the location side where the deflection amount of the light reflection member is maximum toward the spindle side. And a plurality of irregularities are provided on the back surface of the light reflecting member. The invention according to claim 11 is the optical modulator according to claim 9 or 10, characterized in that a plurality of the concavities and convexities are provided only in a region near the spindle on the counter electrode or the back surface. . According to the invention of claim 12, a light reflecting member for reflecting the light from the light source on the front surface, a counter electrode facing the back surface of the light reflecting member with a gap, and a potential difference therebetween are generated. A potential difference generating means and a supporting member for supporting the light reflecting member are provided, and an edge that is a boundary between the supporting member supporting surface and the supporting member side surface that is bent from the supporting member and extends toward the counter electrode is used as a spindle. Then, in the light modulator for bending the light reflecting member toward the counter electrode side by the potential difference to change the reflection direction of the light, from the position side where the bending amount of the light reflecting member is maximum to the spindle side. Toward the supporting shaft, and the deflection angle θ1 of the light reflecting member on the support shaft side is set as follows.
The angle between the support member support surface and the support member side surface is set so as to be larger than the bending angle θ2 at the location side. In addition, claim 1
According to a third aspect of the present invention, a light reflecting member that reflects the light from the light source on the front surface, a counter electrode that faces the back surface of the light reflecting member with a gap, and a potential difference generating means that causes a potential difference between the two. A supporting member for supporting the light reflecting member, wherein the potential difference causes the light reflecting member to bend toward the counter electrode side with the portion supported by the supporting member serving as a spindle to change the reflection direction of the light. In the light modulation device to be changed, the counter electrode is arranged so as to gradually approach from the side where the bending amount of the light reflecting member is maximum toward the support shaft side, and It is characterized in that the support shaft side is more difficult to bend than the above-mentioned location side. According to a fourteenth aspect of the present invention, a light reflecting member that reflects light from the light source on the front surface, a counter electrode that faces the back surface of the light reflecting member with a gap, and a potential difference is generated between the two. The light-reflecting member includes a potential difference generating unit and a supporting member that supports the light reflecting member, and the potential difference causes the light reflecting member to bend toward the counter electrode side with a portion supported by the supporting member as a spindle. In the optical modulation device for changing the reflection direction of the counter electrode, the counter electrode is gradually brought closer to the spindle side from the side where the bending amount of the light reflecting member is maximum, and in the area near the spindle. It is characterized in that they are arranged so as not to face each other. A fifteenth aspect of the present invention is the optical modulator according to any one of the first to fourteenth aspects, including a plurality of combinations of the light reflecting member, the counter electrode, and the supporting member, and the potential difference generating means. However, while causing a common potential difference between the light reflecting member and the counter electrode in each combination, by superimposing a further potential difference on the light reflecting member and the counter electrode only for any combination, It is characterized in that the light reflecting member in any combination is bent.

In these optical modulators having the structure of claim 1, the second counter electrode is located closer to the support shaft (supporting shaft for bending) and the light reflecting member than the first counter electrode. The second potential difference causes an electrostatic force to act on the light reflection member region near the support shaft. Thereby, in the entire area of the light reflecting member, the area in the vicinity of the support shaft (hereinafter,
The support shaft side region) bends and comes into contact with the second counter electrode.
On the other hand, the area relatively far from the spindle is
It bends due to the first potential difference and comes into contact with the first counter electrode. In such contact, if the first potential difference and the second potential difference are set to be the same, the support shaft side region of the light reflecting member is excessively strongly adhered to the second electrode, and both are fixed. May reach. However, the potential difference generating means is
Since the first potential difference and the second potential difference can be set individually, it is possible to keep the second potential difference to a small value that does not cause sticking. Therefore, it is possible to suppress the adhesion between the light reflecting member and the counter electrode. Further, since the second counter electrode is disposed closer to the light reflecting member than the first counter electrode, the supporting shaft side region of the light reflecting member is located farther from the supporting shaft. It is also possible to bend it first. That is, it becomes possible to gradually bend the light reflecting member from a region near the support shaft. In such a configuration, the light reflecting member is entirely bent at a lower potential difference as compared with the conventional light modulator in which the light reflecting member is bent at once by one counter electrode arranged in parallel with the light reflecting member. I can do it. Therefore, increase in the potential difference between the light reflecting member and the counter electrode can be suppressed.

Further, in the optical modulator having the structure of the eighth aspect, of the entire region of the light reflecting member, the region relatively close to the support shaft is the second electrode of the light reflecting member and the counter electrode. It bends due to the potential difference and contacts the counter electrode. On the other hand, the region relatively distant from the support shaft bends due to the potential difference between the first electrode of the light reflecting member and the counter electrode and comes into contact with the counter electrode. In such contact, if the former potential difference and the latter potential difference are set to be the same, the light reflecting member and the counter electrode are excessively strongly adhered to each other around the second electrode of the light reflecting member, so that they are fixed to each other. May reach. However, since the potential difference generating means can set both potential differences individually, it is possible to keep the former potential difference to a small value that does not cause sticking. Therefore, it is possible to suppress the adhesion between the light reflecting member and the counter electrode. Further, the counter electrode region facing the second electrode of the light reflecting member is located closer to the counter electrode region facing the first electrode of the light reflecting member, so that the light reflecting member is moved from the second electrode side to the first electrode side. It is possible to gradually bend it toward the electrode side. In such a configuration, the light reflecting member is entirely bent at a lower potential difference as compared with the conventional light modulator in which the light reflecting member is bent at once by one counter electrode arranged in parallel with the light reflecting member. I can do it. Therefore, increase in the potential difference between the light reflecting member and the counter electrode can be suppressed.

Further, in the optical modulator having any one of the ninth to fourteenth aspects, the counter electrode is arranged closer to the spindle side than to the side where the bending amount of the light reflecting member is maximum. By doing so, a larger electrostatic force can be applied to the light reflecting member than the conventional one in which the both sides have the same distance. And by this, an increase in the potential difference between the light reflecting member and the counter electrode can be suppressed. Further, in the optical modulator having the structure according to claim 9, the plurality of irregularities provided on the surface of the counter electrode facing the light reflecting member have a close contact property with the light reflecting member that comes into contact with the flexing. By lowering it, it is possible to suppress the adhesion between the counter electrode and the light reflecting member. On the other hand, in the optical modulation device having the structure of claim 10, the plurality of irregularities provided on the back surface of the light reflecting member that bends toward the counter electrode lowers the adhesiveness with the counter electrode, so It is possible to suppress sticking to the reflecting member. On the other hand, in the optical modulator having the structure of claim 12, for example, as shown in FIG.
The bending angle θ1 on the fixed end side, which is the support shaft side, is set to be larger than the bending angle θ2 on the free end side, which is the location side where the amount of bending is maximum. This angular relationship is due to the reason described below. That is, the light reflecting member 1 is bent about the edge E1 of the boundary between the supporting surface S1 of the supporting member 40 and the side surface S2 that is bent and extends toward the corresponding electrode 22, and the light reflecting member 1 is bent. This is because the angle θ3 formed by the side surface S2 and the side surface S2 is set to be sufficiently small.
In such a configuration, a stronger restoring force is exerted on the support shaft side of the light reflecting member, which has a stronger adhesive force with the counter electrode, and the mold release from the counter electrode is promoted. Can be suppressed from sticking to. On the other hand, in the optical modulator having the structure according to claim 13, the support shaft side of the light reflecting member, which has stronger adhesion with the counter electrode, is more difficult to bend than the other portions with weaker adhesion. By doing so, a stronger restoring force is exerted on the supporting shaft side. Then, by this, the mold release from the counter electrode on the support shaft side can be promoted, and the fixation of the counter electrode and the light reflecting member can be suppressed. On the other hand, in the optical modulator having the structure of claim 14, since the counter electrode is not disposed so as to face the region in the vicinity of the support shaft of the light reflecting member that has the strongest adhesion with the counter electrode, Adhesion between the neighboring area and the counter electrode is avoided. This makes it possible to prevent the light reflecting member and the counter electrode from sticking to each other.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An optical modulator according to the present invention is for performing optical modulation by changing the reflection direction of incident light. First,
The optical modulator of the first embodiment to which the present invention is applied will be described. FIG. 2A and FIG. 2B are a cross-sectional view and a plan view showing the main configuration of the optical modulator according to the first embodiment. Note that, in FIG. 2 (a), except for a gap G, which will be described later, the cross section is entirely shown.
Only some of them are hatched. Further, in FIG. 2B, which is a plan view, an arbitrary plane is hatched for easy viewing. In other drawings shown below, the hatching of the cross section may be omitted or the plane may be hatched in the same manner.

The light modulator comprises a plurality of light reflecting members 1 (see FIG. 2B). Each light reflecting member 1 receives the incident light L
Is formed by a metal film 1a formed on the front surface side that specularly reflects light, a beam portion 1b formed on the back surface side, and the like. Then, in a state where a plurality of keyboards are arranged side by side, both are supported by the same substrate 20 on both sides. The substrate 20 as a supporting member has a V-shaped cross-sectional shape, and an inverted triangular void G is formed in a portion that does not support the light reflecting member. The substrate 20 has a multi-layer structure including a base layer 21, a thermal oxidation layer 26, a counter electrode layer 23, and the like. Of these layers, the counter electrode layer 23 is the conductive electrode layer 24.
And a protective layer 25 that covers it. Further, the electrode layer 24 includes one V-shaped portion 24a and two flat plate portions 24b.
It consists of and. The V-shaped portion 24a is formed at a position corresponding to the bottom of the V-shaped cross section of the substrate 20, and flat plate portions 24b are formed on both sides of the V-shaped portion 24a. The counter electrode layer 23 is formed by forming the first counter electrode portion 22a composed of the V-shaped portion 24a and the protective layer 25 and the two second counter electrode portions 22b composed of the flat plate portion 24b and the protective layer 25 in such a configuration. There is. The light reflecting member 1 has a gap G for the reason described below.
Bend towards. At this time, the inner edges E of the two substrates each serve as a bending support shaft. Two of the second counter electrode portions 22b
Are formed at positions closer to the spindle than the first counter electrode portion 22a and closer to the light reflecting member 1, respectively.

FIGS. 3 to 11 are explanatory views for explaining the manufacturing process of the main configuration of the optical modulator according to the first embodiment. The manufacturing process will be described with reference to these drawings. [First Step (FIG. 3)] First, a V-shaped groove is patterned on the base layer 21 made of a silicon wafer or the like for a semiconductor process by an organic photoresist method. Specifically, the base layer 21 is dry-etched by reactive ion etching (hereinafter referred to as RIE) using sulfur hexafluoride gas (SF ₆ ) to form a V-shaped groove. At this time, by performing photolithography using a photomask provided with gradation, V-shaped slopes corresponding to the gradation of the photomask can be made to appear in the organic resist pattern. Base layer temperature of -40 [° C] during RIE
When the temperature is set to the following low temperature, a gentle slope can be formed that more faithfully reproduces the gradation of the photomask. After the V-shaped groove is formed in this way, a thermal oxide layer 26 of about 1 [μm] is laminated on the base layer 21. This is to insulate the counter electrode layer 23, which will be formed later, from the base layer 21. [Second Step (FIG. 4)] Next, a conductive electrode layer 24 made of titanium nitride (TiN) or the like is formed on the insulating thermal oxide layer 26 by a sputtering method. Then, after patterning the obtained electrode layer 24 by photolithography of an organic resist, chlorine gas (C
Then, the V-shaped portion 24a and the two flat plate portions 24b are obtained by etching by RIE using (1 ₂ ). Also at this time, the slope of the V-shaped portion 24a can be etched by performing photolithography with a photomask having gradation. A protective layer 25 made of insulating silicon nitride (SiN) is provided on the electrode layer 24 with silane (Si).
It is formed by a thermal CVD (Chemical Vapor Deposition) method using a mixed gas of H ₄ ) and ammonia (NH ₃ ). Also at this time, the V-shaped slope of the protective layer 25 can be formed by performing photolithography using a photomask having gradation. The substrate 20 is formed by the steps so far. [Third step (FIG. 5)] The protective layer 25 is formed by a thermal CVD method (condition of 635 [° C.]) using silane gas (SiH ₄ ).
A sacrificial layer 27 made of polysilicon is formed on the above. [Fourth Step (FIG. 6)] A portion of the sacrificial layer 27 that does not enter the depression of the substrate 20 is formed by chemical mechanical.
Polishing is performed by a polishing technique (hereinafter referred to as CMP). [Fifth Step (FIG. 7)] The beam portion 1b made of silicon nitride (SiN) is formed by a thermal CVD method using a mixed gas of silane (SiH ₄ ) and ammonia (NH ₃ ). [Sixth Step (FIG. 8)] In FIG. 8A, the beam portion 1b is elongated in the depth direction in the drawing. This is divided into a plurality in the depth direction in the figure. Specifically, patterning of the organic resist by photolithography and etching by RIE using methane trifluoride gas (CHF ₃ ) are performed to divide into a plurality of parts as shown in FIG. As a result, a plurality of beam portions 1b that can be supported on both sides are formed on one substrate 20 (however, at this stage, since the sacrifice layer 27 is present, each beam portion 1b is entirely supported. ). Seen from above, each groove 1
The sacrificial layer 27 is exposed from between b. [Seventh Step (FIG. 9)] A metal film 1a made of a light-reflective metal material such as aluminum is formed on the upper side of the groove 1b by a sputtering method. The obtained metal film 1a is divided into a plurality of portions at positions corresponding to the respective beam portions 1b by patterning an organic resist by photolithography and etching by RIE using chlorine gas (Cl ₂ ). With this configuration, a plurality of light reflecting members 1 that can be supported on both sides are formed on one substrate 20 (However, at this stage, since the sacrificial layer 27 exists, each light reflecting member 1 is entirely supported. Has been). [Eighth step (FIG. 10)] One V-shaped portion (not shown)
Then, the electrode pad portions 28 that are individually conducted to the two flat plate portions (not shown) are formed. Specifically, the electrode pad portion 28 made of silicon nitride (SiN) is formed by patterning the organic resist by photolithography and etching by RIE using methane trifluoride gas (CHF ₃ ). [9th step (FIG. 11)] Tetramethyl ammonium
The sacrificial layer 27 is etched by a hydrate (TMAH) from between the metal films 1a.
To remove. As a result, the gap G is formed, and the respective light reflecting members 1 are supported on both sides of the substrate 20.

FIG. 12 is a schematic diagram showing a connection state of each electrode. In the figure, each of the plurality of light reflecting members 1 (strictly speaking, the metal film 1a) is grounded. Electrode pad part 2
The pad 28 a of No. 8 is electrically connected to the V-shaped portion 24 a and is connected to the first power supply control circuit 30. The first power supply control circuit 30 includes a power supply circuit (not shown),
A first potential difference pulse is generated between the V-shaped portion 24a and each light reflecting member 1. On the other hand, the pads 28b arranged on both sides of the pad 28a have two
It is electrically connected to either one of the two flat plate portions 24b and is connected to the second power supply control circuit 31. The second power supply control circuit 31 also includes a power supply circuit (not shown), and is configured to generate a second potential difference pulse between the two flat plate portions 24b and each light reflecting member 1. In the present light modulation device, the electrode pad section 28, the first power supply control circuit 30, the second power supply control circuit 31, various connection wires, and the like constitute a potential difference generating means. When the first potential difference pulse or the second potential difference pulse is generated, an electrostatic force is generated between the substrate 20 and the light reflection member 1 due to the influence thereof. Due to this electrostatic force, the unsupported portion of the light reflecting member 1 bends toward the gap G and contacts the substrate 20.

FIG. 13 is a chart showing simultaneously the time-dependent change of each potential difference pulse generated by the power supply control circuit and the time-dependent change of the deflection amount of the central portion of the light reflecting member (1). The first power supply control circuit (not shown) causes the first potential difference pulse, which is a potential difference between the V-shaped portion 24a and the central portion of the light reflecting member 1, to appear as a rectangular wave as shown in the drawing. ON / OFF. On the other hand, the second power supply control circuit (not shown) causes the second potential difference pulse, which is the potential difference between the two flat plate portions 24b and the vicinity of both ends of the light reflecting member, to appear in synchronization with the first potential difference pulse. . Both potential difference pulses are generated at the same wave height (potential) at the same timing t1, but the second potential difference pulse is
The wave height becomes low at the timing t2. This is because the second power supply control circuit includes two power supply circuits having different voltages and a variable unit that changes the potential difference by switching the power supply circuit to be used, and further lowers the second voltage difference at the timing t2. Because they are doing it. In the present light modulation device, after each potential difference starts to occur at the timing t1,
The time required for the central portion of the light reflecting member 1 to completely come into contact with the V-shaped portion 24a (strictly speaking, the protective layer portion above it) due to bending is obtained by a preliminary test. Then, the timing t2 is set so that the power supply of the second power supply control circuit is switched at the moment when this time elapses. Since the V-shaped portion 24a restricts the further bending of the central portion of the light reflecting member 1 which is fully abutted against the V-shaped portion 24a due to sufficient bending, the bending amount reaches the peak after the timing t2. become.

FIGS. 14A to 14D are sectional views showing the state of the light reflecting member 1 which is gradually bent. When the first and second potential difference pulses are not generated (for example, from t0 to timing t1 in FIG. 13).
Until immediately before), the light reflection member 1 is supported on both sides of the substrate 20 while maintaining its posture in a straight state (FIG. 14).
(A)). When the first and second potential difference pulses are generated,
The region of the light reflecting member 1 facing the flat plate portion 24b bends toward the gap G and starts to contact the second counter electrode portion 22b including the flat plate portion 24b and the protective layer 25 (FIG. 14).
(B)). Then, the flat plate portion 24b of the light reflecting member 1
When the opposing region of and completely contacts the two second counter electrode portions 22b, the central portion of the light reflecting member 1 starts to contact the first counter electrode portion 22a including the V-shaped portion 24a and the protective layer 25 ( FIG. 14 (c)). In this way, the gap G gradually becomes smaller from both ends thereof. Then, eventually, the central portion of the light reflecting member 1 completely contacts the first counter electrode portion 22a, and the gap G disappears (FIG. 14 (d)). As the light reflecting member 1 bends in this way, the reflection direction of the incident light L changes. When the first and second potential difference pulses are turned off,
The light reflecting member 1 is restored to the original straight posture, and the reflection direction of the incident light L is returned to the original direction.

In the conventional cantilever support type optical modulator, when the free end side of the light reflecting member that is bent toward the counter electrode returns to the original position, it does not stop there, but the residual stress. This causes it to bend in the opposite direction. Then, the vibration is subtly freely vibrated so as to invert the bending direction many times, and gradually stopped. Therefore, the flexure recovery (stability) of the light reflecting member is poor, and it is difficult to respond quickly.

However, in the present light modulating device, the light reflecting member 1 tries to bend in the opposite direction due to the residual stress by restraining the light reflecting member 1 at both ends by supporting both ends.
A force that makes it difficult to bend by pulling is applied. As a result, the bending of the light reflecting member 1 can be quickly recovered and a quick response can be realized.

Further, at the timing t2 shown in FIG. 13, by reducing the wave height of the second potential difference pulse, the light reflecting member 1 region which is completely in contact with the second counter electrode portion 22b and the second counter electrode. The potential difference with the portion 22b can be kept to a small value that does not cause sticking of the two. Therefore, it is possible to suppress the adhesion between the light reflecting member 1 and the counter electrode layer 23. In addition, the second potential difference pulse,
As shown in FIG. 13, the wave may be generated as a rectangular wave having a wave height smaller than that of the first potential difference pulse, instead of being generated as a two-step wave whose wave height becomes smaller on the way. By doing so, the sticking can be suppressed more reliably. On the other hand, in the case of the two-step wave as shown in FIG. 13, the response speed can be further increased by increasing the electrostatic force immediately after the pulse is generated to quickly bend the light reflecting member 1.

Further, in the present light modulation device, the second counter electrode portion 22b is disposed closer to the light reflecting member 1 than the first counter electrode portion 22a, and the appropriate first and second potential difference pulses are provided. As a result, the light reflecting member 1 is gradually bent from both end sides thereof as shown in each of the drawings in FIG. In such a configuration, the light reflecting member 1 as a whole has a lower potential difference than the conventional light modulator in which the light reflecting member 1 is bent at a stretch by one counter electrode arranged in parallel with the light reflecting member 1. Can be flexed. Therefore,
It is also possible to suppress an increase in the potential difference between the light reflecting member 1 and the counter electrode layer 23. Even if the second potential difference pulse having a wave height smaller than that of the first potential difference pulse is generated as a rectangular wave, the increase in the potential difference can be suppressed. As the second potential difference pulse causes the vicinity of both ends of the light reflecting member 1 to bend, the center of the light reflecting member 1 is moved to the first position.
This is because the electrostatic force by the first potential difference pulse can be applied to the center of the counter electrode portion 22a in a state where the electrostatic potential is closer to the counter electrode portion 22a.

Further, as shown in FIG. 2B, a plurality of light reflecting members 1 are connected to one common counter electrode layer (one first counter electrode layer).
A combination of the counter electrode portion 22a and the two second counter electrodes 22b) is used for bending. Therefore, compared with the case where each light reflection member 1 is bent by the plurality of counter electrode layers 23, the configuration can be simplified and the cost can be suppressed. When it is desired to individually control the deflection of each light reflecting member 1, a dedicated individual switch 32 may be provided between each light reflecting member 1 and the ground wire as shown in FIG. Good. In FIG. 15, an example in which each electrode pad 28b is connected to the second power supply control circuit via a differentiating circuit constituted by the capacitors 33 and 34 and the resistor 35 to determine the timing t2 by the time constant. Is shown. As a matter of course, the individual switch 32, the capacitors 33 and 34, and the resistor 35 are also components of the potential difference generating means.

The two second counter electrode portions 22b are also provided.
(Strictly speaking, the flat plate portion 24b) has the same second
A potential difference pulse is generated. As a result, as shown in FIG. 12, the two second counter electrode portions 2
It is not necessary to provide a dedicated power supply control circuit for each of 2b, and the cost increase due to the provision of a dedicated power supply control circuit can be eliminated.

The inventors of the present invention actually manufactured an optical modulator having the configuration of the main part shown in FIG. 2 and having the conditions listed below, and conducted an operation test. -Length of light reflection member 1 (beam direction) = 50 [μm] -Thickness of metal film 1a = 50 [nm] -Thickness of beam portion 1b = 70 [nm] -Maximum depth of void G = 2.5 [Μm] ・ Length of first counter electrode portion 22a (depth direction in FIG. 2A) = 27 [μm] ・ Length of second counter electrode portion 22b (〃
) = 10 [μm]

In the optical modulator having such a configuration, the wave height of the first potential difference pulse that can bring the center of the light reflecting member 1 into complete contact with the first counter electrode portion 22a was 50 [V]. Further, the wave height of the second potential difference pulse was gradually reduced in a state where the center of the light reflecting member 1 was completely brought into contact with the first counter electrode portion 22a. Then, the center of the light reflecting member 1 is moved to the first position.
The wave height immediately before starting to separate the vicinity of both ends of the light reflecting member 1 from the second counter electrode portion 22b in the state of being brought into contact with the counter electrode portion 22a was 30 [V] (measured by a laser Doppler vibrometer). ). This is the minimum value required to maintain the contact between the second counter electrode portion 22b and the light reflecting member 1 that is in contact with the second counter electrode portion 22b due to bending. Therefore, the conditions listed below were additionally set. -Wave height of first potential difference pulse = 50 [V] -Initial wave height of second potential difference pulse = 50 [V] -Post wave height of second potential difference pulse = 30 [V] -Width of each potential difference pulse = 5 [μsec]- Pulse cycle = 100 [kHz] ・ Number of pulse occurrences = 5 × 10 ¹¹ [times]

Then, adhesion between the light reflecting member 1 and the counter electrode layer 23 was not observed at all. On the other hand, in the conventional cantilever type optical modulator, sticking started to occur at the time when the pulse was generated about 10 ¹⁰ [times].

[Modification of Light Modulation Device According to First Embodiment] FIGS. 16A and 16B are a cross-sectional view and a plan view, respectively, showing the main configuration of a modification of the light modulation device. As illustrated, two or more flat plate portions 24b may be provided on both sides of the V-shaped portion 24a. In this case, the wave heights of the second potential difference pulses may all be the same, or may be smaller for the flat plate portion 24b located closer to the end. As the number of the flat plate portions 24b is increased, the light reflecting member 1 can be bent more smoothly.

[Other Modifications of Light Modulating Device According to First Embodiment] FIGS. 17A and 17B are a sectional view and a plan view, respectively, showing the structure of the main part of another modification. In these figures, the first counter electrode portion 22a (V-shaped portion 24a) and the second counter electrode portion 22b (flat plate portion 24b) are engaged with each other in a wedge shape while maintaining a predetermined gap and maintaining an insulating state. In addition, the end shape is jagged. With such a configuration, in the region where the ends of the two mesh with each other, it is possible to generate an electrostatic force intermediate between the electrostatic force generated by the first potential difference pulse and the electrostatic force generated by the latter part of the second potential difference pulse. it can. And by this, it becomes possible to bend the light reflection member 1 more smoothly toward the center from the both ends. Further, by flexing smoothly, it is possible to further widen the settable timing of the timing t2.

Next, an optical modulator according to the second embodiment of the present invention will be described. 18 (a) and 18 (b),
3A and 3B are a cross-sectional view and a plan view, respectively, showing the main configuration of the present light modulation device. In these figures, the electrode layer 24 of the counter electrode layer 23 is not divided into a plurality of layers like the optical modulator of the first embodiment, but is a single V-shaped layer. Instead, in the light reflecting member 1, the metal film 1a functioning as an electrode is formed so as to have a planar shape in which wedge-shaped meshes are formed.
It is divided into two. The tip side of one metal film 1 a is located at the center of the light reflecting member 1. The other metal film 1
a has its front end side and rear end side located in the vicinity of each of the two substrate inner edges E. In such a configuration, the former metal film 1a generates an electrostatic force for bending the central portion of the light reflecting member 1, similarly to the V-shaped portion 24a in the optical modulator of the first embodiment. Further, the latter metal film 1a generates an electrostatic force for bending the vicinity of both ends of the light reflecting member 1, similarly to the flat plate portion 24b in the light modulating device of the first embodiment.

An optical modulator having the above-mentioned main structure was actually manufactured. In this light modulator, the minimum value of the first potential difference pulse (potential difference between the former metal film 1a and the counter electrode layer 23 in this example) with which the entire contact of the light reflecting member 1 is obtained is 50 [V]. Met. In addition, a second state that can maintain the contact state between both ends of the light reflecting member 1 and the counter electrode layer 23
The potential difference pulse (potential difference between the latter metal film 1a and the counter electrode layer 23 in this example) was 30 [V]. Therefore, I tried a test run under the conditions listed below. -Length of light reflection member 1 (beam direction) = 50 [μm] -Thickness of metal film 1a = 50 [nm] -Thickness of beam portion 1b = 70 [nm] -Maximum depth of void G = 2.5 [Μm] -Wave height of first potential difference pulse = 50 [V] -Initial wave height of second potential difference pulse = 50 [V] -Post wave height of second potential difference pulse = 30 [V] -Width of each potential difference pulse = 5 [ μsec] ・ Pulse cycle = 100 [kHz] ・ Number of pulse occurrences = 5 × 10 ¹¹ [times]

Then, like the light modulator of the first embodiment, the light reflecting member 1 was not fixed to the counter electrode layer 23.

Next, an optical modulator according to the third embodiment of the present invention will be described. 19A and 19B show
It is sectional drawing and the top view which each show the principal part structure of the optical modulator which concerns on the 3rd Embodiment of this invention. In these drawings, the counter electrode layer 23 does not have a plurality of counter electrode portions as in the optical modulator according to the first embodiment, but has a V-shaped electrode layer 24.
And only one counter electrode portion 22 composed of the protective layer 25 and the protective layer 25 coated thereon. Due to this,
The electrode pad section 28 also includes only one pad.
The counter electrode portion 22 faces the light reflecting member 1 up to the vicinity of the inner edge E of the substrate, which serves as a support shaft for the deflection. Therefore, one counter electrode portion 22 applies an electrostatic force to a region near the support shaft of the light reflecting member.

In the case where the light reflecting member 1 is supported on both sides like the present light modulating device, the central portion located between the two fixed ends of the light reflecting member 1 is the place where the amount of bending becomes maximum.
With respect to this central portion, the valley bottom portion of the V-shaped counter electrode portion 22 is opposed, and the distance from the counter electrode portion 22 is set to be the largest. On the other hand, with respect to the vicinity of the two fixed ends of the light reflection member 1, the vicinity of the apex of the V-shaped counter electrode portion 22 is opposed to the counter electrode portion 2.
The distance from 2 is the smallest. The counter electrode portion 22 is arranged so as to gradually approach from the side where the bending amount of the light reflecting member 1 is maximum toward the fixed end side that is the support shaft side. In such a configuration, a larger electrostatic force can be applied to the light reflecting member 1 than in the conventional configuration in which the counter electrodes are opposed to each other at the same distance between the portion where the deflection of the light reflecting member is maximum and the solid end side. it can. And by this, an increase in the potential difference between the light reflecting member 1 and the counter electrode layer 23 can be suppressed.

A plurality of irregularities 25a are formed on the surface of the protective layer 25 of the counter electrode portion 22. The plurality of concavities and convexities 25a can be formed by, for example, etching the plurality of concavities by a photolithography method using a photomask having a plurality of holes corresponding to the concavities of the concavities and convexities 25a. Specifically, in the second step previously shown in FIG. 4, the protective layer 25 having the V-shaped groove is formed.
The surface of is subjected to etching by the photolithography method. The plurality of irregularities 25a on the surface of the protective layer 25 thus formed do not bring the concave portion into contact with the light reflecting member 1 that comes into contact with it due to bending, so that the contact area with the light reflecting member 1 is greatly increased. Reduce to.
As a result, the adhesiveness with the light reflecting member 1 can be significantly reduced, and sticking with the light reflecting member 1 can be suppressed.

[Modification of Optical Modulation Device According to Third Embodiment] FIGS. 20A and 20B are cross-sectional views showing the configuration of the main parts of a modification of the optical modulation device according to the third embodiment. FIG. In this modified example, the characteristic configuration of the light modulation device according to the third embodiment and the characteristic configuration of the light modulation device according to the first embodiment are simultaneously adopted.
Specifically, the protective layer 2 of the optical modulator according to the first embodiment.
5, a plurality of irregularities 25a are formed on the surface of
The step between the concave portion and the convex portion in the unevenness 25a is 0.1 [μ
m]. With such a configuration, the fixation of the light reflecting member 1 and the counter electrode layer 23 can be reliably suppressed as follows. That is, in addition to reducing the adhesion between the light reflecting member 1 and the counter electrode layer 23 by the plurality of irregularities 25a, the potential difference between the second counter electrode portion 22b and the light reflecting member 1 is small enough not to cause sticking. Keep it at the value.

However, when a plurality of irregularities 25a are provided on the surface of the insulating protective layer 25, the electric field density for bending the light reflecting member 1 toward the counter electrode layer 23 is reduced as compared with the case where it is not provided. . For this reason, the wave height (potential) of the above-mentioned first potential difference pulse and second potential difference pulse must be increased. Of course, the potential difference can be made smaller than in the prior art, but the degree to which it can be made smaller becomes smaller. In general, the drive circuit responsible for driving ON / OFF becomes more expensive as the drive voltage thereof becomes higher. Therefore,
When the degree to which the potential difference can be reduced decreases, it becomes difficult to reduce the cost of the first power supply control circuit and the second power supply control circuit (30, 31: see FIG. 15) functioning as a drive circuit. . If only one first power supply control circuit and one second power supply control circuit are provided, the demerit is relatively small.
The demerits greatly affect that number. For example, the plurality of light reflecting members 1 shown in FIG. 20B and the counter electrode (second counter electrode portion 20a × 1 + first counter electrode portion 20).
It is assumed that a plurality of modulation units including a combination of the substrate 20 as a supporting member including b × 2) are provided. Then, it is assumed that the drive is individually controlled between the modulation units. With such a configuration, if the first power supply control circuit and the second power supply control circuit are provided by the number corresponding to the number of modulation units, the above-mentioned demerit becomes large.

Therefore, in this modified example,
Driving of each modulation unit (driving of the light reflecting member 1) is individually controlled. That is, a common potential difference is generated between the light reflecting member 1 and the “counter electrode” for all the modulation units. On the other hand, with respect to an arbitrary modulation unit, a unit-specific potential difference is superimposed on the light reflecting member 1 and the "counter electrode" by a drive power supply circuit dedicated to that unit.
At this time, the common potential difference is kept at a value at which the light reflection member 1 cannot be bent by itself. Then, when the unit individual potential difference is superposed by the drive power supply circuit, the potential difference is increased to a level at which the light reflecting member 1 can be bent. In such a configuration, the voltage of the drive power supply circuit can be lowered by the common potential difference as compared with the case where the drive for each unit is controlled only by the drive power supply circuit corresponding to each modulation unit.
Therefore, as the driving power supply circuit required for each modulation unit, one with a lower withstand voltage is used.
The cost of the power supply control circuit can be reduced.

The common potential difference generated in each modulation unit may be generated prior to the unit individual potential difference by the drive power supply circuit, or may be generated simultaneously or after a delay. In addition, one first counter electrode portion 22
Regarding the "counter electrode" composed of a and the two second counter electrode portions 22b, a potential difference common to both the first and the second may be generated, or only one of them may be generated. Further, when not driving all the modulation units, it suffices that the unit individual potential difference by the drive power supply circuit is not superposed on all the modulation units. Further, for each modulation unit, by shifting the superposition timing of the unit individual potential difference by the drive power supply circuit,
It is also possible to slightly shift the drive timing.

FIG. 21 is a block diagram showing an example of an electric circuit in this modification. The figure shows an example in which two modulation units can be driven individually. The first power supply control circuit 30 is connected in parallel to each first counter electrode portion 22a of each modulation unit, and causes a common potential difference between the light reflection member 1 and the first counter electrode portion 22a of each modulation unit. In the same manner, the second power supply control circuit 31 has the second counter electrode portions 22 of the respective modulation units.
It is connected in parallel to b and causes a common potential difference between the light reflecting member 1 and the second counter electrode portion 22b in each modulation unit. On the other hand, a plurality of drive power supply circuits 36 are provided so as to correspond to the respective modulation units, and are connected to the first counter electrode portion 22a of the corresponding modulation unit. Then, only for the corresponding modulation unit, the unit individual potential difference is superimposed on the light reflecting member 1 and the first counter electrode portion 22a.

FIG. 22 is a chart showing simultaneously the time-dependent change of each potential difference pulse in the same electric circuit and the time-dependent change of the deflection amount of the central portion of the light reflecting member 1. In the figure, the first potential difference pulse by the first power supply control circuit 30 and the second potential difference pulse by the second power supply control circuit 31 are caused to rise at the same timing t1. However, while the second potential difference pulse is turned off at the subsequent timing t2, the first potential difference pulse lasts longer than the timing t2. The light-reflecting member 1 does not bend just by causing the first potential difference pulse and the second potential difference pulse to occur. Further drive power circuit 3
Only when the unit individual potential difference due to 6 is generated so as to be superimposed on the first potential difference pulse, the light reflection member 1 of the modulation unit bends as shown. Timing t
0, t1, and t2 are set similarly to those in FIG. Therefore, the second potential difference pulse is turned off at the timing t2 when the light reflecting member 1 bent due to the superimposition of the potential difference starts to come into contact with the first counter electrode portion 22a. As a result, when the two are in contact with each other, the potential difference between the light reflecting member 1 and the second counter electrode portion 22b becomes 0 [V], and the electrostatic force between the two is eliminated, so that the fixation of the two is effectively suppressed. .

The inventors of the present invention prototyped an optical modulator including the two modulation units shown in FIG. 21, and attempted to generate each potential difference at the same timing as that shown in FIG. Then, vibration evaluation was performed using a laser Doppler vibrometer. Specifically, the first potential difference pulse having a height of 30 [V] is 5 [μse under an environment of humidity 40 [%].
c] width, and at the same time, the second with a height of 30 [V]
A potential difference pulse was generated with a width of 1 [μsec]. In addition, a drive pulse having a height of 30 [V] was generated at a cycle of 100 [kHz]. Then, the light reflecting member 1 could be bent toward the counter electrode only when the driving pulse [V] was raised. The flexure and the flexure restoration were repeated to bring them into contact with and separate from each other by 6 × 10 ¹¹ [times], but no sticking between the second counter electrode portion 22b and the light reflecting member 1 was observed. As a matter of course, the adhesion between the first counter electrode portion 22a and the light reflecting member was not recognized.

Length of light reflecting member 1 (beam direction), metal film 1
Regarding the thickness of a, the thickness of the beam portion 1b, the maximum depth of the gap G, the length of the first counter electrode portion 22a, and the length of the second counter electrode portion 22b, the optical modulator of the first embodiment is trial-produced. It is similar to the machine. 1 for the light-reflecting member 1 supported by both ends
An experiment was also conducted in which the light reflecting member 1 was bent in a prototype in which two opposing electrodes were arranged in parallel with each other with the same distance as the maximum depth of the gap G. To realize the bending, a potential difference of 80 [V] was applied. Was needed. 20 [V] (80-3
0-30 = 20V) was also able to reduce the potential difference. Furthermore, regarding the drive pulse, the height is set to 3
Since the voltage is kept at 0 [V], it means that the voltage of the drive circuit can be reduced by 50 [V] as compared with the prior art.

FIG. 22 shows an example in which pulse waves are used as the first potential difference (potential difference due to the first counter electrode portion 22a) and the superimposed potential difference for driving, but either one is determined by the continuous application of the DC voltage. It may be non-pulse. Also,
Although the example in which the superimposed potential difference for driving (driving pulse) is superimposed on the first potential difference has been shown, the second potential difference (second counter electrode portion 22b) is shown.
Potential difference).

In the surface of the protective layer (25) facing the light reflecting member 1, only a region near both ends (both fixed ends) where sticking is likely to occur, the above-mentioned plurality of irregularities (2
By providing 5a), the potential difference can be reduced more favorably. This is because the reduction of the electric field density due to the plurality of irregularities is limited to only the area in the vicinity thereof. Specifically, for example, as shown in FIG. 23, the plurality of irregularities 25a are provided on the protective layer 25 only at the location of the second counter electrode portion 22b.

[Other Modifications of Light Modulation Device According to Third Embodiment] FIGS. 24A and 24B show the main configuration of another modification of the light modulation device according to the third embodiment. It is sectional drawing and the top view which are shown. In this other modification, the characteristic configuration of the optical modulation device according to the third embodiment and the characteristic configuration of the optical modulation device according to the second embodiment are simultaneously adopted. Specifically, a plurality of irregularities 25a are formed on the surface of the protective layer 25 of the optical modulator according to the second embodiment, and the step difference between the concave portion and the convex portion in the irregularity 25a is
It is about 0.1 [μm]. With such a configuration, the fixation of the light reflecting member 1 and the counter electrode layer 23 can be reliably suppressed as follows. That is, the plurality of irregularities 25a
Thus, the adhesion between the light reflecting member 1 and the counter electrode layer 23 is reduced. In addition to this, the potential difference between the metal film 1a, which is one of the two metal films 1a meshing in a wedge shape with each other and which bends both end sides (fixed end sides) of the light reflecting member 1, and the light reflecting member 1 is fixed. It should be kept to such a small value that does not cause

However, by providing a plurality of irregularities 25a on the surface of the insulating protective layer 25, as in the previous modification,
The degree to which the potential difference can be reduced becomes smaller than in the conventional case. Then, in the optical modulation device including a plurality of modulation units, the demerit “to reduce the degree to which the voltage of the power supply control circuit can be reduced” becomes large.

Therefore, in this modification, an electric circuit is constructed as shown in FIG. The figure shows an example in which two modulation units can be driven individually. In each modulation unit, two metal films 1 that are engaged with each other in a wedge shape
Of a, those having the both ends (fixed ends) of the light reflecting member 1 flexed are denoted by 1a-B, and those having the central portion flexed are denoted by 1a-A. The first power supply control circuit 30 is connected in parallel to the metal film 1a-A for bending the central portion of each modulation unit, and is connected to the light reflecting member 1 and its metal film 1a-A in each modulation unit. Create a common potential difference. In the same manner, the second power supply control circuit 31 is also connected in parallel to each of the modulation units to the metal film 1a-B of which both ends are bent, and the light reflection member 1 and the metal film thereof in each modulation unit. A potential difference common to 1a-B is generated. On the other hand, a plurality of driving power supply circuits 36 are provided so as to correspond to the respective modulation units, and are connected to the metal film 1a-A for bending the center of the corresponding modulation unit.
Then, only for the corresponding modulation unit, the unit individual potential difference is superimposed on the light reflecting member 1 and the metal film 1a-A for bending the central portion. Also in such a configuration, the cost of the power supply control circuit can be reduced as in the case of the modified example.

The inventors of the present invention prototyped an optical modulator having such a structure and evaluated the vibration. Specifically, humidity 4
In the environment of 0 [%], potential differences as listed below were caused. As the first potential difference pulse by the first power supply control circuit 30, a pulse having a height of 40 [V] and a width of 5 [μsec] is commonly generated in each modulation unit. In order to synchronize the rising timing with this, as the second potential difference pulse by the second power supply control circuit 31, a pulse having a height of 30 [V] and a width of 1 [μsec] is commonly generated in each modulation unit. As the drive potential difference pulse by the drive power supply circuit 36, a pulse having a height of 30 [V] is synchronized with the first potential difference pulse to 1
It was caused to occur at a cycle of 00 [kHz].

Then, the light reflecting member 1 could be bent toward the counter electrode layer 23 only when the drive potential difference pulse was raised. The flexure and the flexure restoration were repeated to bring them into contact with and separate from each other at 5 × 10 ¹¹ times, but no sticking between both end sides of the light reflecting member 1 and the counter electrode layer 23 was observed. As a matter of course, the fixing of the central portion of the light reflecting member 1 and the counter electrode layer 23 was not recognized.

Length of light reflecting member 1 (beam direction), metal film 1
The thickness of a, the thickness of the beam portion 1b, and the maximum depth of the gap G are the same as those of the prototype of the optical modulator of the second embodiment. It was possible to reduce the potential difference by 10 [V] (80-30-40 = 10 V) as compared with the case where the light reflecting member 1 and the counter electrode were arranged in parallel. Further, since the height of the drive pulse is kept at 30 [V], it means that the voltage of the drive circuit can be reduced by 50 [V] as compared with the prior art.

Although the pulse wave is used for each of the first potential difference and the driving superimposed potential difference, either one may be non-pulse by continuous application of the DC voltage. Moreover, although the example in which the driving superimposed potential difference is superimposed on the first potential difference has been described, it may be superimposed on the second potential difference. Further, of the surface of the protective layer 25 facing the light reflecting member 1, both ends (both fixed ends) where sticking is particularly likely to occur.
Providing the plurality of unevennesses 25a only in the vicinity region of the above makes it possible to reduce the potential difference better.

Next, an optical modulator according to the fourth embodiment of the present invention will be described. The present light modulation device is the same as the light modulation device according to the third embodiment except that a plurality of irregularities are provided on the back surface of the beam portion 1b of the light reflection member 1 instead of the protective layer (25). It is configured. The step between the concave portion and the convex portion is about 0.1 [μm]. Even in such a configuration, the potential difference between the light reflecting member 1 and the counter electrode layer 23 is smaller than that in the conventional configuration in which the counter electrode is opposed at an equal distance between the portion where the deflection of the light reflecting member is maximum and the solid end side. The increase can be suppressed. In addition, the plurality of irregularities reduce the adhesion between the light reflecting member 1 and the counter electrode layer 23, so that the adhesion between the two can be suppressed.

Next, an optical modulator according to the fifth embodiment of the present invention will be described. 26 (a) and 26 (b),
It is sectional drawing and the top view which respectively show the principal part structures of the optical modulator which concerns on this 5th Embodiment. In these drawings, the counter electrode layer 23 does not have a plurality of counter electrode portions as in the optical modulator according to the first embodiment, but has a V-shaped electrode layer 24.
And only one counter electrode portion 22 composed of the protective layer 25 and the protective layer 25 coated thereon. Due to this,
The electrode pad section 28 also includes only one pad.
The counter electrode portion 22 faces the light reflecting member 1 up to the vicinity of the inner edge E of the substrate, which serves as a support shaft for the deflection. Then, similar to the optical modulators according to the above embodiments,
The counter electrode portion 22 is arranged so as to gradually approach from the side where the bending amount of the light reflecting member 1 is maximum toward the fixed end side that is the support shaft side. Therefore, the increase in the potential difference between the light reflecting member 1 and the counter electrode layer 23 can be suppressed more than ever before.

At both ends of the substrate 20, which is a supporting member, not the protective layer 25 but the spacer layer 27 coated on the protective layer 25.
The light reflecting member 1 is supported on both sides by. The side surface of the spacer layer 27 facing the gap G is refracted at an angle of about 90 [°] from the upper surface, which is the supporting surface, and extends toward the counter electrode layer 23. The angle between the upper surface of the spacer layer 27 and the upper surface of the counter electrode portion 22 (the inner surface of the V shape) is much larger than 90 [°] as shown in the figure.
The central portion where the amount of deflection of the light reflecting member 1 is the largest is deflected along the upper surface of the counter electrode portion 22, while the fixed end side has a greater deflection angle than this. In such a configuration, as described above with reference to FIG. 38 using the cantilever support method as an example, the bending angle (θ1) at both ends of the light reflecting member 1 that is the support shaft side is set at a position where the bending amount is maximum. It is possible to make it larger than the bending angle (θ2) on the central side.
Then, by exerting a stronger restoring force on both end sides of the light reflecting member 1 having stronger adhesion with the counter electrode layer 23, and promoting mold release from the counter electrode layer 23, the counter electrode layer 23 It is possible to suppress the adhesion between the light reflection member 1 and the light reflection member 1.

The spacer layer 27 can be formed, for example, as follows. That is, in the second step shown in FIG. 4, the SiO ₂ film is formed on the protective layer 25 before the V-shaped groove is formed by the CVD method using the mixed gas of SiH ₄ and N ₂ O. A spacer film having a thickness of 0.2 [μm] is coated. Then, a V-shaped groove may be formed by using buffered hydrofluoric acid or the like having a high selection ratio with the SiN film, and the spacer film may be left only on both ends of the substrate 20.

[Modification of Optical Modulation Device According to Fifth Embodiment] FIGS. 27A and 27B are sectional views showing the configuration of the main parts of a modification of the optical modulation device according to the fifth embodiment. It is a top view. In this modification, the characteristic configuration of the light modulation device according to the fifth embodiment and the characteristic configuration of the light modulation device according to the first embodiment are simultaneously adopted.
Specifically, the protective layer 2 of the optical modulator according to the first embodiment.
The spacer layer 27 is interposed between the light reflection member 1 and the light reflection member 5. With such a configuration, the fixation of the light reflecting member 1 and the counter electrode layer 23 can be reliably suppressed as follows. That is, in addition to exerting a stronger restoring force on both ends of the light reflecting member 1, the potential difference between the second counter electrode portion 22b and the light reflecting member 1 is kept to a small value that does not cause sticking. Of.

However, the spacer layer 2 having a thickness of 0.2 [μm]
By interposing 7 between the counter electrode portions (22a, 2a, 2
Since the distance between 2b) and the light reflection member 1 is increased, the electric field density is reduced as compared with the case where the spacer layer 27 is not interposed. This reduces the degree to which the potential difference can be reduced. Therefore, when a plurality of modulation units are provided, the above-mentioned disadvantages occur.

Therefore, also in the present modification, as in the optical modulator according to the fourth embodiment, the power supply control circuit is constructed by superimposing the common potential difference with respect to the "counter electrode" and the unit individual potential difference by the drive power supply circuit. Has reduced the cost of.

FIG. 28 is a block diagram showing an example of an electric circuit in this modification. The first power supply control circuit 30
It is connected in parallel to each first counter electrode portion 22a of each modulation unit. The second power supply control circuit 31 is also connected in parallel to the respective second counter electrode portions 22b of each modulation unit. On the other hand, a plurality of drive power supply circuits 36 are provided so as to correspond to the respective modulation units, and are connected to the first counter electrode portion 22a of the corresponding modulation unit.

FIG. 29 is a chart showing simultaneously the temporal change of the potential difference pulse of each circuit in the same electric circuit and the temporal change of the deflection amount of the central portion of the light reflecting member 1. In the figure, as the potential difference by the first power supply control circuit 30, not the pulse wave but the DC bias (DC bias for the first potential difference) is commonly generated in each modulation unit. When a drive potential difference pulse, which is a unit individual potential difference by the drive power supply circuit 36, is superposed on this, the light reflecting member 1 bends toward the counter electrode layer (23). At this time, the second potential difference pulse by the second power supply control circuit 31 rises in synchronization with the rise of the drive potential difference pulse.
However, this second potential difference pulse is turned off at a timing t2 earlier than the drive potential difference pulse. Timing t
0, t1, and t2 are set similarly to those in FIG. Therefore, the second potential difference pulse is turned off at the timing t2 when the light reflecting member 1 bent due to the superimposition of the potential difference starts to come into contact with the first counter electrode portion 22a. As a result, when the two are in contact with each other, the potential difference between the light reflecting member 1 and the second counter electrode portion 22b becomes 0 [V], and the electrostatic force between the two is eliminated, so that the fixation of the two is effectively suppressed. .

The first DC bias for potential difference is set to a value such that the deflection of the light reflecting member 1 cannot be maintained by itself. Therefore, the bent light reflecting member 1 is restored after the trailing edge of the drive potential difference pulse. The details of this mechanism are as follows. That is, in the structure in which the spacer layer (27) is interposed between the light reflecting member 1 and the protective layer 25, it is most efficient to bend the light reflecting member 1 in the following order. That is, the opposite electrode layers (23) are gradually brought into contact with each other from both end sides, which are fixed end sides, to the center side. Therefore, with respect to the second potential difference pulse, when it is independently generated, Pull
The height (value) is set so that the contact between both ends of the light reflecting member 1 and the counter electrode layer (23) can be started by a phenomenon similar to -In. The pull-in is a phenomenon in which an abutment of both flat plates suddenly starts at a time when a predetermined potential difference is exceeded in the parallel plate type electrostatic actuator. Therefore, when the second potential difference pulse rises, first, both end sides of the light reflecting member 1 bend and come into contact with the counter electrode layer (23). At this time, as shown in FIG. 29, since the drive potential difference pulse and the first potential difference DC bias are also superposed, the contact portion gradually expands toward the V-shaped valley.
Then, when the contact portion starts to spread to the central portion of the light reflecting member 1 (timing t2), the second potential difference pulse becomes OF.
F will be done. At this time, the superimposed potential difference between the drive potential difference pulse and the first potential difference DC bias is maintained in the central portion. The electrostatic force between the central portion and the counter electrode layer (23) is inversely proportional to the square of the distance between the two, and the timing t
At 2, the distances are very close. For this reason,
Even if the second potential difference pulse is turned off, the central portion of the light reflecting member 1 advances the contact with the counter electrode layer (23) only by the superimposed potential difference.

The DC bias for the first potential difference is set to a value at which the light reflecting member 1 is hardly bent even if the drive potential difference pulse is generated in the state where the second potential difference pulse is not generated. In such a setting, when the drive potential difference pulse is turned off and only the first potential difference DC bias is generated, the waist strength of the light reflecting member 1 overcomes the electrostatic force due to the bias and is largely bent. The light reflecting member 1 that has been removed is restored.

The inventors of the present invention prototyped an optical modulator including two modulation units shown in FIG. 28, and evaluated vibration while generating each potential difference at the same timing as that shown in FIG. It was Specifically, under a humidity of 40%, a second potential difference pulse having a height of 30 [V] and 1 [μsec] is generated while applying a first potential difference bias having a height of 40 [V]. I'm sorry. Further, in order to synchronize with the rising of the second potential difference pulse, the height 30
A drive pulse of [V] was generated at a cycle of 100 [kHz]. Then, the central portion of the light reflecting member 1 could be brought into contact with the counter electrode layer (23) only when the drive pulse [V] was raised. The flexure and the flexure restoration were repeated and both were brought into contact with and separated from each other by 5 × 10 ¹¹ [times], but no fixation between the second counter electrode portion 22b and the light reflecting member 1 was observed.
As a matter of course, the adhesion between the first counter electrode portion 22a and the light reflecting member was not recognized. In contrast, in supported at both ends scheme parallel arranged to each other, in contact and separation of 10 10 ^[times], the second
Adhesion between the counter electrode portion 22b and the light reflecting member 1 occurred.
Note that, although FIG. 29 shows an example in which a DC bias is adopted for the first potential difference, a pulse wave may be adopted. The length of the light reflection member 1 (beam direction), the thickness of the metal film 1a, the thickness of the beam portion 1b, the maximum depth of the gap G, and the first counter electrode portion 22a.
And the length of the second counter electrode portion 22b are the same as those of the prototype of the optical modulator of the first embodiment.

[Other Modifications of Optical Modulation Device According to Fifth Embodiment] FIGS. 30 (a) and 30 (b) respectively show the main configuration of another modification of the optical modulation device according to the fifth embodiment. It is sectional drawing and the top view which are shown. In this other modification, the characteristic configuration of the optical modulation device according to the fifth embodiment and the characteristic configuration of the optical modulation device according to the second embodiment are simultaneously adopted. Specifically, a thickness of 0.2 [μ is provided between the protective layer 25 and the light reflecting member 1 of the light modulation device according to the second embodiment.
[m] spacer layer 27 is interposed.
With such a configuration, the fixation of the light reflecting member 1 and the counter electrode layer 23 can be reliably suppressed as follows. That is, a stronger restoring force is exerted on both ends of the light reflecting member 1. In addition to this, 2
Of the two metal films 1a-A and 1a-B, the metal film 1a-B that bends both ends of the light reflecting member 1 and the light reflecting member 1
The potential difference between and is kept to a small value that does not cause sticking.

However, the spacer layer 2 having a thickness of 0.2 [μm]
By interposing 7 between the counter electrode portions (22a, 2a, 2
Since the distance between 2b) and the light reflection member 1 is increased, the electric field density is reduced as compared with the case where the spacer layer 27 is not interposed.

Therefore, in this modification, an electric circuit is constructed as shown in FIG. The figure shows an example in which two modulation units can be driven individually. The first power supply control circuit 30 is connected in parallel to each of the modulation units to the metal film 1a-A of which the central portion is bent. Similarly, the second power supply control circuit 31 is also connected in parallel to each of the modulation units to the metal film 1a-B whose both ends are bent. On the other hand, a plurality of driving power supply circuits 36 are provided so as to correspond to the respective modulation units, and are connected to the metal film 1a-A for bending the center of the corresponding modulation unit. Also in this configuration, the same drawing shows an example in which two modulation units can be individually driven. In each of the modulation units, of the two metal films 1a meshing with each other in a wedge shape, 1a is the one that bends both ends (fixed ends) of the light reflecting member 1.
-B, the one in which the central portion is bent is denoted by reference numeral 1a-A. The first power supply control circuit 30
Each modulation unit is connected in parallel to the metal film 1a-A of which the central portion is bent, and a common potential difference is generated between the light reflection member 1 and its metal film 1a-A in each modulation unit. In the same manner, the second power supply control circuit 31 is also connected in parallel to each of the modulation units to the metal film 1a-B of which both ends are bent, and the light reflection member 1 and the metal film thereof in each modulation unit. A potential difference common to 1a-B is generated. On the other hand, a plurality of drive power supply circuits 36 are provided so as to correspond to the respective modulation units, and are connected to the metal film 1a-A for bending the center of the corresponding modulation unit. Then, only for the corresponding modulation unit, the light reflecting member 1
Then, the unit individual potential difference is made to overlap with the metal film 1a-A whose center portion is bent. Also in such a configuration, the cost of the power supply control circuit can be reduced as in the case of the modified example.

The inventors of the present invention prototyped an optical modulator having such a structure and evaluated vibration. Specifically, humidity 4
In the environment of 0 [%], potential differences as listed below were caused. As the first potential difference by the first power supply control circuit 30, a direct current bias having a height of 40 [V] is commonly generated in each modulation unit. As the first potential difference pulse by the second power supply control circuit 31, a pulse having a height of 30 [V] and a width of 1 [μsec] is commonly generated in each modulation unit. -The height of the driving pulse from the driving power supply circuit 36 is 30.
Those of [V] were caused to occur at a cycle of 100 [kHz] in synchronization with the rising of the second potential difference pulse.

By repeating the bending and the restoration of the bending, the light reflecting member 1 was brought into contact with and separated from the counter electrode layer 23 by 5 × 10 ¹¹ [times], but both ends of the light reflecting member 1 and the counter electrode layer 23 were separated. No sticking was observed. As a matter of course, the fixing of the central portion of the light reflecting member 1 and the counter electrode layer 23 was not recognized.
The length of the light reflecting member 1 (beam direction), the thickness of the metal film 1a, the thickness of the beam portion 1b, and the maximum depth of the gap G are the same as those of the prototype of the light modulator of the second embodiment. is there.

Next, an optical modulator according to the sixth embodiment of the present invention will be described. 32 (a) and 32 (b),
It is sectional drawing and the top view which show the main part structure of the optical modulation apparatus which concerns on this 6th Embodiment, respectively. In these drawings, the counter electrode layer 23 has only one counter electrode portion 22 including a V-shaped electrode layer 24 and a protective layer 25 covering the V-shaped electrode layer 24. The counter electrode portion 22 faces the light reflecting member 1 up to the vicinity of the inner edge E of the substrate, which serves as a pivot of the bending. Then, similarly to the light modulators according to the above-described embodiments, the counter electrode portion 22 is directed from the side where the bending amount of the light reflecting member 1 is maximum to the fixed end side that is the support shaft side.
Are arranged so as to gradually approach each other. Therefore, the increase in the potential difference between the light reflecting member 1 and the counter electrode layer 23 can be suppressed more than ever before.

At both ends of the substrate 20, which is a supporting member, the light reflecting member 1 is supported on both sides by the backup layer 28, which is covered thereon, not by the protective layer 25. These backup layers 28 are not only interposed between the supporting end surface of the light reflecting member 1 and the horizontal supporting surface of the protective layer 25, but project toward the gap G. Then, of the surface of the light reflecting member 1 facing the counter electrode portion 22, the regions near both ends are backed up. As a result, both ends of the light reflecting member 1 on the supporting shaft side are more difficult to bend than the center side. With such a configuration, a stronger restoring force is exerted on both end sides of the light reflecting member 1, which has a stronger adhesive force with the counter electrode layer 23. Then, by this, release from the counter electrode layer 23 can be promoted, and sticking between the counter electrode portion 22 and the light reflection member 1 can be suppressed. It should be noted that the both ends of the light reflecting member 1 may be made harder to bend by backing up with the backup layer 28, rather than being made harder to bend.

[Modification of Light Modulation Device According to Sixth Embodiment] FIGS. 33A and 33B are cross-sectional views showing the configuration of the main parts of a modification of the light modulation device according to the sixth embodiment, respectively. It is a top view. In this modification, the characteristic configuration of the light modulation device according to the sixth embodiment and the characteristic configuration of the light modulation device according to the first embodiment are simultaneously adopted.
Specifically, the protective layer 2 of the optical modulator according to the first embodiment.
5, the backup layer 28 is interposed between the light reflection member 1 and the light reflection member 1. With such a configuration, the fixation of the light reflecting member 1 and the counter electrode layer 23 can be reliably suppressed as follows. That is, in addition to exerting a stronger restoring force on both ends of the light reflecting member 1, the second
The potential difference between the counter electrode portion 22b and the light reflecting member 1 is kept to a small value that does not cause sticking.

However, by exerting a stronger restoring force on both end sides, the degree to which the potential difference can be reduced decreases. Therefore, when a plurality of modulation units are provided, the above-mentioned disadvantages occur. Therefore, also in this modification, an electric circuit as shown in FIG. 34 is adopted, and the common potential difference by the first power supply control circuit 30 and the drive power supply circuit 36.
The cost of the power supply control circuit is reduced by the method of superimposing the unit individual potential difference due to.

The present inventors prototyped an optical modulator including the two modulation units shown in FIG. The backup areas at both ends of the light reflecting member 1 in this prototype are
The distance from each fixed end was 10 [μm]. Further, the thickness of the backup layer 28 was set to 150 [nm]. Length of light reflection member 1 (beam direction), thickness of metal film 1a, thickness of beam portion 1b, maximum depth of gap G, length of first counter electrode portion 22a, length of second counter electrode portion 22b Are the same as those of the prototype of the optical modulator of the first embodiment.

Vibration evaluation was performed using this prototype. Specifically, in an environment with a humidity of 40%, the height 30
The first potential difference pulse of [V] was generated in the width of 5 [μsec], and at the same time, the second potential difference pulse of 30 [V] in height was generated in the width of 1 [μsec]. Also, height 30
A drive pulse of [V] was generated at a cycle of 100 [kHz]. Then, the light reflecting member 1 could be bent toward the counter electrode only when the driving pulse [V] was raised. Repeat flexion and flexure restoration to make both 6 × 10
^{After 11} times of contact, the second counter electrode portion 22b and the light reflecting member 1 were not fixed to each other. As a matter of course, the adhesion between the first counter electrode portion 22a and the light reflecting member was not recognized.

[Other Modifications of Optical Modulation Device According to Sixth Embodiment] FIGS. 35 (a) and 35 (b) show the main configuration of another modification of the optical modulation device according to the sixth embodiment. It is sectional drawing and the top view which are shown. In this other modification, the characteristic configuration of the light modulation device according to the sixth embodiment and the characteristic configuration of the light modulation device according to the second embodiment are simultaneously adopted. Specifically, the backup layer 2 is provided between the protective layer 25 and the light reflecting member 1 of the optical modulator according to the second embodiment.
8 is interposed. With such a configuration, the fixation of the light reflecting member 1 and the counter electrode layer 23 can be reliably suppressed as follows. A stronger restoring force is exerted on both ends of the light reflecting member 1. Of the two metal films 1a meshing with each other in a wedge shape, the potential difference between the metal film 1a-B that bends both ends of the light reflecting member 1 and the light reflecting member 1 is limited to a small value that does not cause sticking. Of.

However, by exerting a stronger restoring force on both end sides of the light reflecting member 1, the degree to which the potential difference can be reduced decreases. Therefore, when a plurality of modulation units are provided, the above-mentioned disadvantages occur. Therefore, also in this modification, an electric circuit as shown in FIG. 36 is adopted, and a common potential difference by the first power supply control circuit 30 and a unit individual potential difference by the drive power supply circuit 36 are superposed on each other. The cost is reduced.

The present inventors prototyped the optical modulator shown in FIG. 36 and evaluated vibration. Specifically, under the environment of humidity 40 [%], the potential differences as listed below were caused. As the first potential difference pulse by the first power supply control circuit 30, a pulse having a height of 40 [V] and a width of 5 [μsec] is commonly generated in each modulation unit. In order to synchronize the rising timing with this, as the second potential difference pulse by the second power supply control circuit 31, a pulse having a height of 30 [V] and a width of 1 [μsec] is commonly generated in each modulation unit. As the drive potential difference pulse by the drive power supply circuit 36, a pulse having a height of 30 [V] is synchronized with the first potential difference pulse to 1
It was caused to occur at a cycle of 00 [kHz].

Then, the light reflecting member 1 could be bent toward the counter electrode layer 23 only when the drive potential difference pulse was raised. The flexure and the flexure restoration were repeated to bring them into contact with and separate from each other at 5 × 10 ¹¹ times, but no sticking between both end sides of the light reflecting member 1 and the counter electrode layer 23 was observed. As a matter of course, the fixing of the central portion of the light reflecting member 1 and the counter electrode layer 23 was not recognized.

Next, an optical modulator according to the seventh embodiment of the present invention will be described. FIG. 37 is a sectional view showing the arrangement of the main parts of the optical modulation device according to the seventh embodiment. The counter electrode layer 23 does not have a plurality of counter electrode portions as in the optical modulator according to the first embodiment, but has a V-shaped electrode layer 24 and a protective layer 25 coated thereon. It has only one counter electrode portion 22 composed of. The counter electrode portion 22 faces the light reflecting member 1 up to the vicinity of the inner edge E of the substrate, which serves as a pivot of the bending. Then, similarly to the light modulators according to the above-described embodiments, the counter electrode portion 22 gradually becomes closer to the fixed end side, which is the spindle side, from the location side where the bending amount of the light reflecting member 1 is maximum. It is arranged so as to approach. Therefore, the increase in the potential difference between the light reflecting member 1 and the counter electrode layer 23 can be suppressed more than ever before.

The length of the V-shaped electrode layer 24 in the lateral direction in the drawing is smaller than that of the second embodiment.
As a result, the counter electrode portion 22 does not face the area in the vicinity of the fixed end serving as the spindle. In such a configuration, since the counter electrode portion 22 is not disposed so as to face the area near the fixed end of the light reflecting member 1 where sticking is particularly likely to occur, sticking between the near area and the counter electrode is avoided. ing. This makes it possible to prevent the light reflecting member and the counter electrode from sticking to each other.

So far, in each of the embodiments and modifications,
I have explained the double-supported optical modulator,
The present invention can also be applied to a cantilever support type optical modulator.

As described above, according to the optical modulators of the respective embodiments,
It is possible to suppress the increase in the potential difference between the light reflecting member 1 and the counter electrode layer 23, and also to prevent the two from sticking to each other. Also, the first
In the light modulator of the embodiment, the plurality of light reflecting members 1
Are bent by one common counter electrode layer 23. Therefore, compared with the case where each light reflection member 1 is bent by the plurality of counter electrode layers 23, the configuration can be simplified and the cost can be suppressed. In addition, regarding the first counter electrode portion 22a and the second counter electrode portion 22b, FIG.
As shown in (b), if the end portions are meshed with each other in a wedge shape while maintaining the insulating state, the following electrostatic force can be generated in the region where the mutual end portions are meshed with each other. That is, it is an electrostatic force about the middle of the electrostatic force generated by the first potential difference pulse and the electrostatic force generated by the latter part of the second potential difference pulse. As a result, the light reflecting member 1 can be bent more smoothly from both ends thereof toward the center. Furthermore, by smoothly bending, it is possible to further widen the settable timing of the timing t2. In addition, the two second counter electrode portions 22b
With respect to the above, since the same second potential difference pulse is generated, it is not necessary to provide a dedicated power supply control circuit for each, and it is possible to eliminate the increase in cost. Further, the second power supply control circuit 31 forming a part of the potential difference generating means has a varying means for varying the wave height of the second potential difference pulse, and the wave height can be changed stepwise. Therefore, the electrostatic force immediately after the pulse is generated by the occurrence of the multi-step wave (two-step wave in the illustrated example) as shown in FIG. 13 and the light reflecting member 1 is swiftly bent, so that the response speed is further increased. You can speed it up. In addition, the lower limit of the wave height of the second potential difference pulse is set to be equal to or more than the minimum value required to maintain the contact between the second counter electrode portion 22b and the light reflecting member 1 that is in contact with the second counter electrode portion 22b due to bending. By doing so, the following situations can be avoided. In other words, the center of the light reflecting member 1 is brought into contact with the counter electrode layer 23 while the both ends of the light reflecting member 1 are separated from each other. Then, it is possible to avoid destabilization of the light reflection direction due to this situation. In addition, since the turning on of the first and second potential difference pulses is started, the central portion of the light reflecting member 1 is bent to form the V-shaped portion 2
The time required for completely contacting 4a is previously obtained by a test, and the moment when this time elapses is set to the timing t2. Therefore, even if a special sensor for detecting the contact between the light reflection member 1 and the V-shaped portion 24a (strictly speaking, the protective layer above the V-shaped portion 24a) is not provided, the wave height of the second potential difference pulse after the contact between the two is achieved. Can be made smaller.

Further, in the optical modulation device according to the third embodiment, a plurality of plural electrodes are provided only in the area near the fixed end in the "counter electrode" composed of the first counter electrode portion 22a and the two second counter electrode portions 22b. If the unevenness 25a is provided, the light reflecting member 1 can be bent with a smaller potential difference.

Further, in the light modulating device according to the third embodiment, even if a plurality of irregularities 25a are provided only in the region on the back surface of the light reflecting member 1 near the fixed end, the light reflecting member 1 is bent with a smaller potential difference. I can do it.

Further, in each of the embodiments, while a common potential difference is generated between the light reflecting member 1 and the counter electrode in each modulation unit, a further potential difference is generated between the light reflecting member 1 and the counter electrode only for an arbitrary combination. , The cost of the power supply control circuit can be reduced.

[0088]

According to the first to fifteenth aspects of the present invention, there is an excellent effect that it is possible to suppress the increase of the potential difference between the light reflecting member and the counter electrode, and at the same time, to suppress the fixation of both.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a main part of an optical modulator under development by the present inventors.

FIG. 2A is a cross-sectional view showing the main configuration of the optical modulator according to the first embodiment. FIG. 6B is a plan view of the main configuration.

FIG. 3 is a cross-sectional view showing a first manufacturing process of the configuration of the main part.

FIG. 4 is a cross-sectional view showing a second manufacturing step of the configuration of the main part.

FIG. 5 is a cross-sectional view showing a third manufacturing step of the configuration of the main part.

FIG. 6 is a cross-sectional view showing a fourth manufacturing step of the configuration of the main part.

FIG. 7 is a cross-sectional view showing a fifth manufacturing step of the configuration of the main part.

FIG. 8A is a cross-sectional view showing a sixth manufacturing step of the configuration of the main part. FIG. 6B is a plan view showing the sixth manufacturing step.

FIG. 9A is a sectional view showing a seventh manufacturing step of the configuration of the main part. FIG. 13B is a plan view showing the seventh manufacturing process.

FIG. 10A is a cross-sectional view showing an eighth manufacturing step of the configuration of the main part. FIG. 13B is a plan view showing the eighth manufacturing process.

FIG. 11A is a sectional view showing a ninth manufacturing step of the configuration of the main part. (B) The top view which shows the 9th manufacturing process.

FIG. 12 is a schematic diagram showing a connection state of each electrode having the same main configuration.

FIG. 13 is a chart showing simultaneously a temporal change of each potential difference pulse generated by the power supply control circuit and a temporal change of a bending amount of the central portion of the light reflecting member.

14A to 14D are cross-sectional views showing states of the light reflecting member 1 that are gradually bent.

FIG. 15 is a schematic diagram showing the same connection state that can be adopted when it is desired to individually control the deflection of each light reflecting member.

FIG. 16A is a cross-sectional view showing the configuration of the main parts of a modified example of the optical modulation device. FIG. 3B is a plan view of the main configuration of the same.

FIG. 17A is a cross-sectional view showing the configuration of the main part of another modification. FIG. 3B is a plan view of the main configuration of the same.

FIG. 18A is a cross-sectional view showing the main configuration of a modification of the optical modulation device according to the second embodiment. FIG. 3B is a plan view of the main configuration of the same.

FIG. 19A is a cross-sectional view showing a main configuration of an optical modulator according to a third embodiment. FIG. 3B is a plan view showing the configuration of the main part.

FIG. 20A is a cross-sectional view showing a configuration of a main part of a modified example of the same light modulation device. FIG. 3B is a plan view showing the configuration of the main part.

FIG. 21 is a block diagram showing an example of an electric circuit according to the modified example.

FIG. 22 is a chart showing simultaneously a temporal change of each potential difference pulse in the electric circuit and a temporal change of a bending amount of a central portion of the light reflecting member.

FIG. 23 is a cross-sectional view showing an example in which a plurality of irregularities are provided only in the regions near both ends of the light reflecting member in the modification.

FIG. 24A is a cross-sectional view showing the main configuration of another modification of the optical modulation device according to the third embodiment. FIG. 3B is a plan view showing the configuration of the main part.

FIG. 25 is a block diagram showing an example of an electric circuit according to another modification.

FIG. 26A is a cross-sectional view showing the main configuration of an optical modulator according to a fifth embodiment. FIG. 3B is a plan view showing the configuration of the main part.

FIG. 27A is a cross-sectional view showing the configuration of the main parts of a modified example of the same light modulation device. FIG. 3B is a plan view showing the configuration of the main part.

FIG. 28 is a block diagram showing an example of an electric circuit according to the modified example.

FIG. 29 is a chart showing simultaneously a temporal change of each potential difference pulse in the same electric circuit and a temporal change of a bending amount of a central portion of the light reflecting member.

FIG. 30A is a cross-sectional view showing the main configuration of another modification of the optical modulator according to the fifth embodiment. FIG. 3B is a plan view showing the configuration of the main part.

FIG. 31 is a block diagram showing an example of an electric circuit according to another modification.

FIG. 32A is a sectional view showing a configuration of a main part of an optical modulator according to a sixth embodiment, and FIG. 32B is a plan view showing the configuration of the same.

FIG. 33A is a cross-sectional view showing a main part configuration in a modification of the optical modulator according to the sixth embodiment, and FIG. 33B is a plan view showing the same main part configuration.

FIG. 34 is a block diagram showing an example of an electric circuit according to the modified example.

FIG. 35A is a cross-sectional view showing the main configuration of another modification of the optical modulator according to the sixth embodiment. FIG. 3B is a plan view showing the configuration of the main part.

FIG. 36 is a block diagram showing an example of an electric circuit according to another modification.

FIG. 37 is a cross-sectional view showing the main-part configuration of an optical modulator according to a seventh embodiment.

FIG. 38 is a schematic diagram showing the relationship between the bending angle θ1 on the fixed end side and the bending angle θ2 on the free end side in the light reflecting member when the cantilever support method is adopted.

[Explanation of symbols]

1 Light reflection member 1a Metal film 1b Beam part 20 Substrate (support member) 21 Base layer 22 Counter electrode 22a First counter electrode portion (first counter electrode) 22b Second counter electrode portion (second counter electrode) 23 Counter electrode layer 24 electrode layers 24a V-shaped part 24b Flat plate part 25 Protective layer 26 Thermal oxide layer 27 Sacrificial layer 28 Electrode pad 30 First power supply control circuit 31 Second power supply control circuit 32 individual switches

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Goichi Otaka             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh F-term (reference) 2H041 AA12 AA14 AA16 AB14 AC06                       AZ02 AZ05 AZ08

Claims (15)

[Claims] 1. A light reflecting member for reflecting light from a light source on a front surface, a counter electrode facing the back surface of the light reflecting member with a gap, and a potential difference generating means for generating a potential difference therebetween. A supporting member that supports the light reflecting member, and the potential difference causes the light reflecting member to bend toward the counter electrode side with the portion supported by the supporting member serving as a spindle. In the optical modulator for changing, a first counter electrode and a second counter electrode arranged closer to the support shaft and the light reflecting member than the first counter electrode are provided as the counter electrode.
A second potential difference between the second counter electrode and the light reflecting member
An optical modulator, wherein the potential difference generating means is configured so that a potential difference and a first potential difference which is a potential difference between the first counter electrode and the light reflecting member can be individually set. 2. The light modulation device according to claim 1, wherein a plurality of the light reflecting members are provided, and these are reflected by the common first counter electrode and second common electrode. apparatus. 3. The light modulating device according to claim 1, wherein the first counter electrode and the second counter electrode have an end shape that meshes in a wedge shape while maintaining an insulating state from each other. Modulator. 4. An optical modulator according to claim 1, 2 or 3, wherein the supporting member is configured to support both ends of the light reflecting member, and corresponds to the two support shafts respectively generated at both ends. The light modulation device is characterized in that the two potential counter electrodes are provided, and the potential difference generating means is configured to generate the same second potential difference for each of the second counter electrodes. 5. The optical modulator according to claim 1, 2, 3 or 4, wherein the potential difference generating means has a second potential difference varying means. 6. An optical modulator according to claim 1, 2, 3, 4 or 5, wherein said variable means is adapted to contact said second counter electrode with said light reflecting member abutting against said second counter electrode. An optical modulator, wherein the second potential difference is changed with a minimum value necessary for maintaining contact being a lower limit. 7. The optical modulator according to claim 5, wherein the variable means changes the second potential difference to a smaller value after a lapse of a predetermined time from the start of generation of the second potential difference. 8. A light reflecting member for reflecting light from a light source on a front surface, a light reflecting member electrode fixed to the front surface, a counter electrode facing the back surface of the light reflecting member with a gap, and the light reflecting member. A supporting member for supporting the member, and a potential difference generating means for generating a potential difference between the light reflecting member electrode and the counter electrode,
And a potential difference that causes the light-reflecting member to bend toward the counter electrode with a portion supported by the supporting member as a spindle, thereby changing the light-reflecting direction. As the electrodes, a light reflecting member first electrode and a light reflecting member second electrode for causing the potential difference at a position closer to the supporting shaft than this are provided, and a counter electrode facing the light reflecting member second electrode. The region is located closer to the counter electrode region facing the light reflecting member first electrode, and the potential difference between the counter electrode and the light reflecting member second electrode, the counter electrode and the first counter electrode. An optical modulation device characterized in that the potential difference generating means is configured so that the potential difference between and can be individually set. 9. A light reflecting member for reflecting light from a light source on a front surface, a counter electrode facing the back surface of the light reflecting member with a gap, and a potential difference generating means for generating a potential difference between the two. A supporting member for supporting the light reflecting member, wherein the potential difference causes the light reflecting member to bend toward the counter electrode side with the portion supported by the supporting member serving as a spindle to change the reflection direction of the light. In the light modulation device for changing, the counter electrode is arranged so as to gradually approach from the location side where the deflection amount of the light reflection member is maximum toward the support shaft side, and the light in the counter electrode is changed. An optical modulator, wherein a plurality of irregularities are provided on a surface facing a reflecting member. 10. A light reflecting member for reflecting light from a light source on a front surface, a counter electrode facing the back surface of the light reflecting member through a gap, and a potential difference generating means for generating a potential difference between the two. A supporting member supporting the light reflecting member,
In the light modulation device that bends the light reflecting member toward the counter electrode by changing the potential of the light reflecting member around the portion supported by the supporting member as a spindle by the potential difference, the bending amount of the light reflecting member. From the maximum point side to the above spindle side,
An optical modulator, wherein the counter electrodes are arranged so as to gradually approach each other, and a plurality of irregularities are provided on the back surface of the light reflecting member. 11. The light modulation device according to claim 9 or 10, wherein a plurality of the irregularities are provided only in a region near the support shaft on the counter electrode or the back surface. 12. A light reflecting member for reflecting light from a light source on a front surface, a counter electrode facing the back surface of the light reflecting member with a gap, and a potential difference generating means for generating a potential difference between the two. A supporting member supporting the light reflecting member,
The light reflecting member is bent toward the counter electrode side by the potential difference with an edge that is a boundary between the support member support surface and the support member side surface that is bent and extends toward the counter electrode. In the light modulator for changing the reflection direction of the light, the counter electrode is arranged so as to gradually approach from the side where the bending amount of the light reflecting member is maximum toward the spindle side, and The angle between the supporting member supporting surface and the supporting member side surface is set so that the bending angle θ1 of the light reflecting member on the support shaft side is larger than the bending angle θ2 on the location side. Light modulator. 13. A light reflecting member for reflecting light from a light source on a front surface, a counter electrode facing the back surface of the light reflecting member with a gap, and a potential difference generating means for generating a potential difference between the two. A supporting member supporting the light reflecting member,
In the light modulation device that bends the light reflecting member toward the counter electrode by changing the potential of the light reflecting member around the portion supported by the supporting member as a spindle by the potential difference, the bending amount of the light reflecting member. From the maximum point side to the above spindle side,
An optical modulator, wherein the counter electrodes are arranged so as to gradually approach each other, and the support shaft side of the light reflecting member is more difficult to bend than the location side. 14. A light reflecting member for reflecting light from a light source on a front surface, a counter electrode facing the back surface of the light reflecting member with a gap, and a potential difference generating means for generating a potential difference between the two. A supporting member supporting the light reflecting member,
In the light modulator for changing the reflection direction of the light by bending the light reflection member toward the counter electrode with the portion supported by the support member serving as a spindle by the potential difference, An optical modulator characterized in that the reflecting member is arranged so as to gradually approach the supporting shaft side from the side where the bending amount of the reflecting member is maximum and not to face the region near the supporting shaft. 15. The light modulation device according to claim 1, further comprising a plurality of combinations of the light reflection member, the counter electrode, and the support member, and the potential difference generation means in each combination. While causing a common potential difference between each of the light reflecting member and the counter electrode in, the additional potential difference is superimposed on the light reflecting member and the counter electrode only for any combination, A light modulation device characterized in that the light reflecting member is bent.