JP3151069B2 - Light bulb - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light valve, and more particularly, to a small light valve for controlling a light amount using a moving member.

[0002]

2. Description of the Related Art At present, main light valves include a mechanical diaphragm used for adjusting a light amount of a camera or the like, a liquid crystal cell or a P-type liquid crystal cell.
A solid-state optical shutter that controls the amount of light emitted from the back surface in a small area using the electro-optic effect of a ferroelectric material such as LZT (Journal of the Institute of Electronics Photography, Vol. 30, No. 4, 1991,
pp. 447 to 494). Among them, the optical shutter is an optical deflector such as an optical switch used for switching an optical fiber transmission line or a terminal device, an optical printer head of an electrophotographic printer by forming a one-dimensional array, and a liquid crystal cell on a two-dimensional surface. Various applications such as a liquid crystal display to be arranged are being studied.

A mechanical light valve, as an optical element for optical communication such as an optical switch, can deflect or block light regardless of the wavelength of light. Therefore, when a multi-wavelength light source is used or the wavelength of the light source fluctuates. Although useful in certain cases, it is inferior to solid-state optical shutters in terms of high-speed response, miniaturization, arraying, and the like, and has limited application fields.

In recent years, micromachines having a very small movable mechanism using a photolithographic process have been studied by micromechanics technology. A typical micromachine is a wobble micromotor (M. Mehregany et a
l., "Operation of microfabricated harmobic and ordi
nary side-drive motors ", Proxeedings IEEE Micro Ele
ctro Mechanical Systems Workshop 1990, p1-8) and linear microactuators (P. Cheung et al., "Mode
ling and position-detection of a polysiliconlinear
microactuator ", Micromechanical Sensors, Actuators,
and Systems ASME 1991, DS C-Vol.32.p269-278). These micromachines are manufactured by a semiconductor photolithography process and can be easily arrayed and reduced in cost, and high-speed response can be expected by miniaturization. Optical deflectors and interferometers have been proposed as mechanical optical elements. In an optical deflector, a Dot-matrix display (Gal
lagher, "Microshutters Flipof Form Characters in Do
t-matrix display ".Electronics, 1983.7.14.p81-82),
There is a spatial light modulator (Japanese Unexamined Patent Publication No. 2-8812), and the interferometer is a Fabry-Perot interferometer (“A. Miniature Fabry-Perot Inte
rferometer Fabricated Using Silicon Micromachinig
Techniques ”, IEEE Solid-State Sensor And Actuator
workshop 1988.p16-18) has been proposed.

[0005]

However, in the above-described optical deflector, the element can be downsized and can be used as an optical shutter. However, in order to utilize the reflection of light, a light source is irradiated from above the element. Therefore, there is a problem that it is difficult to reduce the size of the entire image forming apparatus including the light source and the lens system. In the interferometer, since the wavelength is selected by the amount of bending of the membrane, it is necessary to make the membrane large, and there is also a problem that it is difficult to make the interferometer small and to form an array.

Also, these mechanical optical elements have a problem that it is difficult to adjust the amount of light and to provide a gradation expression for each pixel.

The present invention has been made in view of the above-mentioned problems of the prior art, and is a mechanical light valve that is small in size and easy to form an array. It is an object of the present invention to provide a light valve capable of adjusting the amount of light and capable of adjusting and controlling the amount of light at high speed.

[0008]

According to a first aspect of the present invention, there is provided a light valve according to the present invention, in which a moving member is displaced by a displacing means to adjust and control the amount of light incident from the rear surface of the moving member. In a small light valve, a light transmitting portion is formed in part, and the light transmitting portion has a substrate on which a plurality of fixed electrodes are fixedly provided so as to displaceably support the moving member and interpose a gap with an end of the moving member. The displacement means is to apply a voltage to the fixed electrode to generate an induced charge in the moving member, and to adjust the amount of light passing through the light transmitting portion by displacing the moving member, Further, the substrate is formed of glass, the light transmitting portion is formed by removing a part of a light shielding film formed on one surface of the glass, or the substrate is formed of a Si substrate, The transmitting portion is formed by removing a part of the Si substrate, and the moving member is formed of a rotating plate, and the rotating plate is rotatably supported by a rotating support formed on the substrate. Things and the moving member,
The fixed electrode fixed to the substrate and the fixed electrode fixed to the end are formed integrally with a guide portion for supporting the moving member, and are formed on the guide portion. The fixed electrode may be formed such that a gap is formed between the moving member and the moving member. The fixed electrode may have a hole formed in the moving member.

[0009]

The light valve according to the present invention configured as described above has a light transmitting portion formed on a part of the substrate, and is supported and interposed with a plurality of fixed electrodes fixed on the substrate through a gap. If a movable member is provided, and a voltage is applied to the fixed electrode by the displacement means to generate an induced charge in the movable member, the movable member is displaced to the fixed electrode side, and if the voltage applied to the fixed electrode is changed, The amount of light passing through the light transmitting portion formed on the substrate is adjusted by the moving member.

[0010]

1 to 14 show an embodiment of the present invention.
This will be described in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a plan view of a light valve according to a first embodiment of the present invention. FIG. 2 is a sectional view taken along line AA of FIG.

As shown in FIGS. 1 and 2, a light transmitting portion 3 for transmitting incident light 2 from the back surface of the substrate 1 is formed in the Si substrate 1. Incident light 2 incident from the back surface of the Si substrate 1 exits the surface of the substrate 1 through a light transmitting portion 3 provided on the substrate 1. On the other hand, on the upper surface of the substrate 1, a rotation support portion 4 serving as a rotation axis is formed, and the rotation support portion 4 rotatably supports a rotation portion 5 as a disk-shaped moving member. A window 6 as a hole through which the incident light 2 can be transmitted is formed in the rotating portion 5, and the incident light 2 transmitted through the light transmitting portion 3 is formed.
Exits above the substrate 1 through this window 6. Around the rotating unit 5, fixed electrodes 8 having a gap 7 with the rotating unit 5 are fixed at equal intervals so as to surround the rotating unit 5.

When a voltage is applied to the fixed electrode 8 fixed to the rotating part 5 via the gap 7, an electrostatic attraction acts between the rotating part 5 and the fixed electrode 8. Thus, when a voltage is sequentially applied to each of the plurality of fixed electrodes 8, the rotating unit 5 rotates while being in contact with the rotation supporting unit 14. At this time, the light transmitting portion 13
The amount of transmitted light can be adjusted by the overlapping area of the window 16 and the window 16 provided in the rotating unit 15.

The rotating part and the fixed electrode of the first embodiment of the light valve according to the present invention employ the aforementioned wobble micromotor manufactured by micromechanics technology.

Here, the manufacturing process of the first embodiment of the light valve according to the present invention will be described with reference to the process chart shown in FIG.

In the manufacturing method of this embodiment, an opening 13 is formed by forming a silicon nitride film 12 on both surfaces of a Si substrate 11 by low pressure CVD (LPCVD) and patterning a part of one surface by photolithography and etching. (FIG. 3A). The etching was performed by reactive ion etching (RIF) using CF ₄ as a reaction gas.

Next, an Si membrane 14 as shown in FIG. 3B is formed by anisotropic etching utilizing an etching rate difference between Si crystal orientation planes. The anisotropic etching is performed by heating a KOH aqueous solution. The thickness of the membrane may be about several tens μm as long as it does not break on handling when performing photolithography or the like.

After a polysilicon film is formed by LPCVD and patterned, phosphorus is implanted by an ion implantation method to form an electric shield portion 15 of a rotating portion and a rotating supporting portion (FIG. 3C).

First sacrificial layer 1 by vacuum sputtering
6 to become SiO ₂ was patterned after 2μm deposited (FIG. 3 (D)).

Next, a polysilicon film is formed to a thickness of 2.5 μm by LPCVD and then patterned, and phosphorus is ion-implanted to form a rotating part 17 as a moving member, a window 18 and a fixed electrode 19 (FIG. 3 ( E)).

The second sacrificial layer 21 is formed by a vacuum sputtering method.
SiO ₂ film is formed is, the polysilicon film is patterned after the 1μm deposited, forming a rotating support part 20 by the phosphorus ion implantation (FIG. 3 (F)).

The Si membrane 14 is etched from the back surface by RIE using SF ₆ as a reaction gas to form the light transmitting portion 13, and finally, the SiO ₂ film is removed by etching with a hydrofluoric acid aqueous solution (FIG. 3 (G)). To form a light valve. At this time, when removing the membrane by RIE, S
The iO ₂ film becomes an etch stop layer and the rotating part is not etched, and the silicon nitride film may be removed. Here, the silicon nitride film is left in order to prevent the air flow from the light transmitting portion to the rotating portion from flowing and alienating the displacement operation.

The light valve thus manufactured is
It can be made very small and lightweight as an array. The radius of the rotating part is set to 100 μm, the gap is set to 1.5 μm, and a voltage 5 is sequentially applied in synchronization with each fixed electrode fixed around the rotating part.
By applying 0 V, a rotation speed of 500 Hz or more can be achieved. This makes it possible to turn on and off the transmitted light at a high speed of several milliseconds or less with respect to the light that is constantly incident. The amount of light can be adjusted.

In FIG. 3, an opening portion obtained by etching a Si membrane is used as a light transmitting portion. However, an opening area of the Si membrane is set to an appropriate size, and a part of an electric shield portion is opened to be used as a light transmitting portion. May be. Also,
Here, a Si substrate was used, but K. Suzuki et al. ("Singk
e Crysral sillcon rotational micromotors ".Proceedi
ngs IEEE Micro Electro Mechanical Systems 1991, p15
A glass substrate can also be used if the method of forming a silicon substrate on which a rotating portion as a moving member, a fixed electrode portion, and the like are formed on a glass substrate by bonding the substrate to the substrate is used. In the manufacturing process of the light valve according to the first embodiment of the present invention, a moving member made of a polysilicon film is used. However, B. Frazier et al. (“DESING AND FABRICATION OF ELECT
ROPLATED MICROMOTOR STRUCTURES ", Micromechanical S
ensors, Actuators, and Systems ASME 1991, DSX-Vol.3
It goes without saying that the light valve may be formed by using a metal obtained by electrolytic deposition according to 2.p135-146). Further, in the light valve of the first embodiment, one window is provided in the moving member as shown in FIG. 1, but, for example, as shown in FIG. A plurality of open windows 6 (FIG. 1) may be provided. Thus, when the rotation direction is defined, the light transmitting portion 3 (FIG. 1)
It is possible to improve the speed of blocking the incident light from the window by a multiple of the window. Further, in the light valve of the first embodiment, the incident light is from the lower surface of the substrate, but it goes without saying that the light may be incident from above the rotating part side as the moving member.

Next, an application example to which the light valve of this embodiment is applied will be described.

FIG. 5 shows an example of a 1.times.6 optical switch when this embodiment is used in an optical fiber communication network.

In the light valve 32 shown in the figure, only the moving member is shown in a simplified manner. As shown in FIG. 5C, the substrate 38 is provided with a light transmitting portion 40 through which all the incident light emitted from the optical fiber bundle 31 can be transmitted. Thereby, the substrate 3
As for the light incident from the lower surface of 8, the light only under the window 37 of the rotating part 36 can be selectively extracted on the substrate.

An optical switch is one of the most important optical control components used for switching an optical fiber transmission line or a terminal device. The light valve 32 can transmit and block the incident light 33 from the six optical fiber bundles 31 through the window 37 of the rotating unit 36 (FIG. 5C).
In this way, it is possible to selectively take out and make optical information incident on another optical fiber 35 via the rod lens 34. The conventional rotary optical switch with mechanically driven reflector (Ishizuka, National Tech. Report, 27, p118, 1981) has the advantage of low insertion loss and leakage, but has the problem of slow switching speed. The light valve of the present invention can be easily reduced in size, can increase the mechanical resonance frequency, and can increase the switching speed.

(Second Embodiment) FIG. 6 is a perspective view showing a second embodiment of the light valve of the present invention. FIG. 7 shows B in FIG.
FIG. 4 is a sectional view taken along line B.

The form of the moving member and the fixed electrode shown here is the linear microactuator shown in the above description of the prior art. According to the fabrication method of K. Suzuki and others,
The moving member 46 and the fixed electrode 48 which were previously formed on the i-substrate were bonded to the glass substrate 41 by an anodic bonding method, and Si was removed by etching except for the pattern portion to obtain a light valve shown in FIG.

FIG. 6 shows a second embodiment of the light valve according to the present invention.
This will be described with reference to FIG.

As shown in FIG. 7, a light-shielding film 42 having an opening 43 is formed on one of both surfaces of a glass substrate 41, and a transmission portion 44 is provided on the opposite surface at a position facing the opening 43. An electric shield part 45 is formed. Above the glass substrate 41, a moving member 46 that can move horizontally with one surface of the glass substrate 41 is supported. A window 47 as a hole is formed in the moving member 46, and the amount of light is adjusted by allowing incident light from the opening 43 on the back surface of the glass substrate 41 to pass through the window 47 provided in the moving member 46. . As shown in FIG. 6, the movable member 46 is supported by a pair of opposed central portions of a flexible beam 50 having four sides, and the opposed flexible beam 50 that does not directly support the movable member 46 is flexible. The beam fixing portion 49 is fixed to the glass substrate 41. At the center of each end of the moving member 46 not supported by the opposing flexible beam 49, a comb-shaped member is formed extending in the direction of the flexible beam fixing portion 49, respectively. The glass substrate 41 is engaged with the
A comb-shaped fixed electrode 48 is formed on the upper surface.

In order to move the movable member 46, a voltage is applied to the comb-shaped fixed electrode 48 through a gap to generate an electrostatic attraction, whereby the flexible beam 50 is bent and displaced in the Y direction in the drawing. . The opening 43 of the light shielding film 42
And the incident light passing through the transmission section 44 of the electrostatic shield 45 is shielded, and the light amount can be adjusted. Light shielding film 4
In step 2, the incident light is substantially blocked, and the amount of incident light is precisely restricted by the transmission section 44 formed in the electric shield section 45.
The moving member 46 and the fixed electrode 48 have a Si thickness of 5 μm,
The length of the flexible beam 50 is set to 500 μm, the number of the comb-shaped fixed electrodes 48 is set to 35, the gap is set to 1.5 μm, the gap between the glass substrate 41 and the moving member 46 is set to 2 μm. 0.1 μm / V in the direction. Thus, by changing the voltage applied to the comb-shaped fixed electrode, it is possible to arbitrarily change the overlapping area between the window 46 and the transmission section 44.

In the above embodiment, the light valve having the movable member which can move in only one direction has been described. However, the present invention is not limited to this.

FIG. 8 shows a light valve that can be displaced in the X and Y directions shown. In the same manner as in the above-described second embodiment, the moving member 51 is supported at the center of the four sides thereof with a gap provided between the movable member 51 and the substrate via the flexible beams 55 shown in FIG. It is fixed to the substrate via a flexible beam fixing portion 54. Each of the flexible beams 55 has a comb portion formed in the X and Y directions, and fixed electrodes 53 are fixed on the substrate so as to mesh with the comb portion via a gap.

In order to displace the moving member 51, the flexible beam 55 bends and displaces due to an electrostatic attraction generated by applying a voltage to the comb-shaped fixed electrode similarly to the light valve shown in FIG. Thus, by selecting the fixed electrode in the direction to be displaced and applying a voltage, the window 52 formed in the center of the moving member 51 can be moved in the X and Y directions.

Next, an application example of the second embodiment of the light valve of the present invention will be described.

FIG. 9 shows a light valve array 62 in which the light valves 61 according to the second embodiment of the present invention are arrayed on one substrate.
FIG. FIG. 10 shows an application example of this light valve array 62 to electrostatic printing. Light from a linear light source 63 such as a fluorescent lamp is radiated to the light valve array 62, and light incident on each light valve is passed through a window provided in a transmission part and a moving member, and a selfoc lens array or a micro lens array is used. The incident light is imaged on the photosensitive drum 65 by the lens system 64 such as. 3 light bulbs
Drive control is possible up to about kHz, which makes it possible to obtain a sufficient response speed even when compared with a conventional optical shutter utilizing a change in the refractive index of a liquid crystal shutter array or the like, and directly without using a polarizer. It is possible to adjust the amount of light.

FIG. 11 shows a moving member 67 for each light valve.
FIG. 6 is a diagram illustrating an operation when the amount of light passing through is changed by shifting the amount of displacement of. As described above, the incident light 68 emitted from the light transmitting portion 66 formed on the glass substrate 69 is changed in the amount of light by shifting the amount of displacement of the moving member 67 for each light valve. Area gradation expression for each pixel formed in a drum shape can be realized.

Further, as shown in FIG.
By providing several types of color filters 73 on the back surface of the light source 2, incident light 71 from a light source such as a fluorescent lamp is passed through the color filters, and this light is transmitted to a moving member 74
It is possible to colorize by controlling with. Further, by arranging the one-dimensional array shown in FIG. 9 two-dimensionally, application to an image forming apparatus such as a display is also possible.

(Third Embodiment) FIG. 13 is a plan view showing a light valve according to a third embodiment of the present invention. FIG. 14 shows FIG.
3 is a sectional view taken along line AA of FIG.

As shown in FIG. 13, a light shielding film 83 having a rectangular light transmitting portion 91 is formed on a glass substrate, and a moving member 81 is moved by a plurality of guide portions on the upper surface of the light shielding film 83. It is kept possible. As shown in FIG. 14, the moving member 81 is supported with a gap provided between the upper guide portion 84 and the lower guide portion 75 via a fixed electrode 87 therebetween. Similarly, the moving member 81 is supported by a vertical guide having a fixed electrode 86. Each of the upper and lower guide portions is arranged so as to substantially protrude from each fixed electrode so that the moving member 65 does not contact the fixed electrode, and forms a gap. The moving member 81 does not have a window unlike the light valves shown in the first and second embodiments.

To move the moving member, the fixed electrode 86
, An induced charge is generated in the moving member 65, and the moving member 81 is displaced toward the fixed electrode 86. After displacing the moving member 81 in the direction of the fixed electrode 86, the voltage of the fixed electrode 86 is turned off, and then the voltage is applied to the fixed electrode 88. Thereby, the moving member 81 moves in the direction of the fixed electrode 88. By sequentially applying a voltage to each fixed electrode in this manner, the moving member 81 moves on the light transmitting portion 91 of the light shielding film 83 and blocks light incident through the light transmitting portion 91. By moving the moving member to an appropriate position, the overlapping area of the light transmitting portion and the moving member can be changed, and the light amount can be adjusted.

[0044]

Since the present invention is configured as described above, the following effects can be obtained.

In the light valve of the present invention, a light transmitting portion is formed on a substrate, and a movable member which is supported and displaceable through a gap with a plurality of fixed electrodes fixedly provided is provided. When a voltage is applied to the movable member, an induced charge is generated in the movable member, and the movable member can be moved in the direction of the fixed electrode. Therefore, by forming the moving member near the light transmitting portion, the amount of light passing through the light transmitting portion can be adjusted by changing the voltage of the fixed electrode by the moving member.

Since such a light valve of the present invention is manufactured by a semiconductor photolithography process, it is easy to reduce the size and to form an array. Further, by reducing the size, the light valve of the present invention can adjust the amount of light at high speed.

[Brief description of the drawings]

FIG. 1 is a plan view of a first embodiment of a light valve according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a process diagram showing a manufacturing process of the first embodiment of the light valve of the present invention.

FIG. 4 is a view showing another embodiment of the rotating unit shown in FIG. 1;

FIG. 5 is a diagram illustrating an example of a 1 × 6 optical switch when the first embodiment of the present invention is used in an optical fiber communication network.

FIG. 6 is a perspective view showing a second embodiment of the light valve of the present invention.

FIG. 7 is a sectional view taken along the line BB of FIG. 6;

FIG. 8 is a view showing a second embodiment of the light valve of the present invention which can be displaced in the X and Y directions.

FIG. 9 is a view showing a light valve array in which a second embodiment of the light valve of the present invention is arrayed on one substrate.

FIG. 10 is a diagram showing an application example of a light valve array to electrostatic printing.

11 is a diagram for explaining the operation of the light valve array shown in FIG.

FIG. 12 is a diagram showing an application example of the second embodiment of the light valve of the present invention to colorization.

FIG. 13 is a plan view showing a third embodiment of the light valve of the present invention.

FIG. 14 is a sectional view taken along line AA of FIG.

[Explanation of symbols]

 1,11 Si substrate 2,33,68,71 Incident light 3,22,40,44,66,89 Light transmission part 4,20 Rotation support part 5,17,36 Rotation part 6,18,37,47,52 , 75 window 7 gap 8, 19, 48, 53, 86, 87, 88 fixed electrode 12, 39 silicon nitride film 13, 43 opening 14 Si membrane 15, 45 electric shield part 16 first sacrificial layer 21 second Sacrifice layer 31 Optical fiber bundle 32, 61 Light valve 34 Rod lens 35 Optical fiber 38 Substrate 41, 69, 72, 82 Glass substrate 42, 83 Light shielding film 46, 51, 67, 74, 81 Moving member 49, 54 Flexible beam Fixed part 50, 55 Flexible beam 62 Light valve array 63 Light source 64 Lens system 65 Photoconductor drum 73 Color filter 84 Upper guide part 85 Lower guide part

Continuation of the front page (72) Inventor Hiroshi Takagi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-3-22885 (JP, A) JP-A-4-325883 ( JP, A) JP-A-4-156508 (JP, A) JP-A-4-328715 (JP, A) JP-A-62-265623 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , (DB name) G02B 26/00-26/08

Claims (7)

(57) [Claims] 1. A small light valve in which a moving member is displaced by a displacing means to adjust and control the amount of light incident from the rear surface of the moving member, wherein a light transmitting portion is formed in part, and the moving member is And a substrate on which a plurality of fixed electrodes are fixedly mounted so as to be able to displace and move the moving member by interposing a gap with an end of the moving member, wherein the displacing means applies a voltage to the fixed electrode to move the moving member. A light valve, wherein an amount of light passing through the light transmitting portion is adjusted by generating an induced charge in the moving member and displacing the moving member. 2. The substrate according to claim 1, wherein the substrate is formed of glass, and the light transmitting portion is formed by removing a part of a light shielding film formed on one surface of the glass. Light bulb. 3. The light valve according to claim 1, wherein the substrate is formed of a Si substrate, and the light transmitting portion is formed by removing a part of the Si substrate. 4. The light valve according to claim 1, wherein the moving member comprises a rotary plate, and the rotary plate is rotatably supported by a rotary support formed on the substrate. 5. The light valve according to claim 1, wherein the moving member is supported by a flexible beam whose end is fixed. 6. The fixed electrode fixed to the substrate is formed integrally with a guide portion for supporting the moving member, and the fixed electrode formed on the guide portion is provided with a gap with the moving member. The light valve according to claim 1, wherein the light valve is formed as: 7. The light valve according to claim 1, wherein a hole is formed in the moving member.