JP3800820B2 - Active micro optical element and image display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an active optical element that performs optical switching by moving a micro optical element by a micromachine, and an image display apparatus.
[0002]
[Prior art]
Conventionally, in this type of microactuator, a voltage is applied between the intermediate electrode and the upper or lower electrode to move the intermediate electrode up and down. In addition, an insulating film is provided on the upper and lower electrodes on the intermediate electrode side, and the insulating layer prevents the intermediate electrode from moving and contacting the upper or lower electrode. The insulating layer also served as an upper limit or lower limit stopper when the intermediate electrode moved.
[0003]
Usually, two or four springs connected to the intermediate electrode are mainstream, and one end of each spring is fixed by a support member.
[0004]
[Problems to be solved by the invention]
In the case of a printer head or an image display element in which micro optical elements are arranged in a line or array, the size of the elements arranged in a line or array is low in power consumption and low cost. Therefore, the smaller one is desirable. In order to make the element small, it is necessary to make each micro optical element small. Along with this, it is necessary to make the constituent members of the actuator portion small, but a certain size is required to satisfy the required displacement amount.
[0005]
Therefore, there arises a problem that the effective length of the spring is shortened and the drive voltage is increased. In addition, when there are two or more spring support portions, there is a problem that the area of the electrode cannot be obtained due to the area of the spring and the spring support portion, the electrode area is reduced, and the drive voltage is increased.
[0006]
Also, the intermediate electrode prevents the upper electrode from contacting the upper or lower electrode with an insulating layer, and the intermediate electrode is an upper or lower stopper when the intermediate electrode moves. It stopped in contact with the surface. When the electrode voltage is switched to leave the insulating layer, it comes in contact with the surface and stops, causing problems such as the actuator not moving or the moving speed slowing due to adverse effects such as adsorption and air damping.
[0007]
The present invention has been made to solve the above-mentioned problems, and realizes a smaller active micro-optical element array that can be driven up and down with a very simple structure, does not cause adsorption, and is a reliable microactuator. The main object is to provide an active micro optical element and an image display element.
[0008]
[Means for Solving the Problems]
The configuration of the present invention for solving the above problems is as follows.
1) In an active optical element having a micro optical element and a micro actuator, an electrode is provided above and below the intermediate electrode, the micro actuator has one spring support, and the intermediate electrode is supported by a single spring. The intermediate electrode has a coupling portion with the micro optical element, and is coupled to the micro optical element by one or more coupling portions.
[0009]
2) In an electrostatically driven microactuator having an array of microactuators and drive circuits, an intermediate electrode is provided between the lower and upper electrodes, and an intermediate electrode is applied depending on the applied voltage between the intermediate electrode and the lower electrode or the upper electrode. The intermediate electrode is supported via a spring structure, and when the potentials of the lower electrode, the intermediate electrode, and the upper electrode are equal, the distance between the intermediate electrode and the lower electrode, and between the intermediate electrode and the upper electrode A feature is that the intervals are not equal.
[0010]
3) In an electrostatically driven microactuator having an array of microactuators and drive circuits, make the potential of the intermediate electrode equal to the potential of the intermediate electrode of one or more adjacent microactuators, and the potential difference between the intermediate electrode and the lower electrode When this occurs and stops moving downward, a part of the intermediate electrode comes into contact with a part of the column supporting the spring connected to the adjacent intermediate electrode.
[0011]
4) At least one potential of the intermediate electrode is set in an active micro-optical element in which the micro-optical element is moved by an electrostatically driven micro-actuator having a driving circuit for each micro-actuator. When the potential of the intermediate electrode of the adjacent microactuator is made equal, a potential difference is generated between the intermediate electrode and the lower electrode, and when moving downward, the bottom surface or part of the connecting portion between the intermediate electrode and the micro optical element, or The bottom surface of the intermediate electrode comes into contact with a part of the support supporting the spring connected to the adjacent intermediate electrode and stops.
[0012]
5) In an active micro optical element in which the micro optical element moves by a micro optical element, a micro actuator, and an electrostatic drive type micro actuator having a drive circuit for each micro actuator, the electrodes are located above and below the intermediate electrode, There is a coupling portion with the micro optical element, and the coupling portion couples with the micro optical element. The coupling portion is made of a conductor or an insulator, and the bottom surface of the micro optical element is made of an insulator, and an intermediate electrode When the potential difference is generated between the lower electrode and the lower electrode and the lower electrode moves downward, the upper surface of the upper electrode and a part or all of the lower surface of the micro optical element come into contact with each other to stop the micro optical element.
[0013]
6) An active micro-optical element that has an intermediate electrode between the micro-actuator, drive circuit, and lower and upper electrodes, and the micro-optical element connected to the intermediate electrode moves to perform optical switching operation. When moved upward, a stopper is provided above the micro optical element to define the position of the micro optical element. When the micro optical element comes into contact with the stopper and stops, the upper surface of the intermediate electrode (the surface on the upper electrode side) and the upper The lower surface of the electrode (the surface on the intermediate electrode side) is not in contact with at least the entire surface.
[0014]
7) By forming an array of active micro optical elements as described in 1), 3), 4), 5) and 6), an optical switching element in the form of an array is formed, and an image is displayed by the optical switching element array. Features.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Example 1
FIG. 1 is a schematic view showing an actuator portion in Embodiment 1 of the present invention. 2 is a cross-sectional view taken from 108 to 109 in FIG. Reference numeral 101 denotes a lower electrode located on the lowermost surface of the actuator provided on the drive circuit. The spring 104 is supported by a support column 105 that supports the spring, and the other end is connected to the intermediate electrode 102. A part of the upper surface of the intermediate electrode has a connection portion 103 with the optical element 203. Above the intermediate electrode is an upper electrode 106 supported by a support column 107. By adopting such a structure, the space utilization efficiency has been dramatically improved, the springs are long, and the areas of the upper and lower electrodes can be increased. Therefore, an active micro optical element that is driven at 5 V and is firmly connected to the actuator has been realized.
[0016]
(Example 2)
An electrostatic actuator according to the second embodiment will be described with reference to FIG. 1 and FIG. 2 showing a cross-sectional view from 108 to 109 in FIG. An attractive force is generated by applying a potential difference between the lower electrode 101 and the intermediate electrode 102, and the intermediate electrode 102 moves downward. Similarly, an attractive force is generated by applying a potential difference between the upper electrode 106 and the intermediate electrode 102, and the intermediate electrode 102 moves upward. The intermediate electrode 102 is connected to the spring 104 and the other end is fixed to the support column. Therefore, the same spring constant is obtained when the intermediate electrode moves upward and downwards due to electrostatic force. In the case of an electrostatic actuator, the driving voltage decreases in inverse proportion to the electrode area, and the driving voltage increases in proportion to the square of the driving distance. In the case of the actuator shown in the second embodiment, the connection portion 103 for connecting to the micro optical element 203 is required, so that the area of the upper electrode 106 is smaller than that of the lower electrode 101. In this state, if the distance between the intermediate electrode and the upper and lower electrodes is the same, the pull-in voltage will be reached unless the potential difference applied to the upper electrode and the intermediate electrode is made larger than the potential difference applied to the lower electrode and the intermediate electrode. Absent. Therefore, by making the interval 201 between the intermediate electrode and the upper electrode narrower than the interval 202 between the intermediate electrode and the lower electrode, even if the applied voltages of the upper and lower electrodes are the same, the pull-in can be performed in the same manner.
[0017]
By adopting such a structure, in Example 2, the upper and lower pull-in voltages can be set to 5 V, and the drive voltage can be achieved to 5 V or less for both the upper and lower electrodes.
[0018]
Example 3
FIG. 3 is a schematic diagram illustrating an actuator unit according to the third embodiment of the present invention. 4 is a cross-sectional view taken from 302 to 303 in FIG. The strut 105 of the spring 104 and the intermediate electrode 102 connected to the spring are made of a conductive material, and the spring struts 105 of the actuators arranged in an array are connected to each other in the drive circuit below. Yes. A part 301 of the spring column 105 overlaps the intermediate electrode 102 in a plan view. The lower electrode is insulated and protected by the insulating layer 401 on the intermediate electrode side. When a potential difference is generated between the lower electrode 101 and the intermediate electrode 104 and the electrode 104 moves downward, a part of the spring 104 comes into contact with an adjacent spring column like 402. In this way, when the adjacent spring strut and a part of the spring are in contact with each other, a gap 403 exists between the intermediate electrode 104 and the insulating layer 401 of the lower electrode.
[0019]
The electric charge accumulated in the intermediate electrode can escape from the column every time it contacts the spring column, and has an effect of preventing charging. Further, since the contact between the intermediate electrode 104 and the insulating layer 401 of the lower electrode is avoided, adverse effects such as adsorption can be prevented.
[0020]
(Example 4)
FIG. 5 is a schematic diagram illustrating an actuator unit according to a fourth embodiment of the present invention. FIG. 6 is a cross-sectional view taken from 502 to 503 in FIG. The column 105 of the spring 104 and the intermediate electrode 102 connected to the spring are made of a conductive material, and the coupling portion 103 connecting the optical element 601 intermediate electrode 102 is also conductive. The spring struts 105 of the actuators arranged in an array are connected to each other in the lower drive circuit. A part 501 of the spring column 105 overlaps the coupling portion 103 in a plan view. The lower electrode is insulated and protected by the insulating layer 401 on the intermediate electrode side. When a potential difference is generated between the lower electrode 101 and the intermediate electrode 104 and the lower electrode 101 and the intermediate electrode 104 move downward, a part of the coupling portion 103 comes into contact with an adjacent spring post like a frame 603. In this way, when the adjacent spring strut and a part of the coupling portion 103 are in contact with each other, a gap 602 exists between the intermediate electrode 104 and the insulating layer 401 of the lower electrode.
[0021]
The electric charge accumulated in the intermediate electrode can escape from the support through the conductive coupling member every time it comes into contact with the spring support, and has the effect of preventing charging. Further, since the contact between the intermediate electrode 104 and the insulating layer 401 of the lower electrode is avoided, adverse effects such as adsorption can be prevented. In the fourth embodiment, the coupling portion is made of a conductive material. However, even if it is an insulator, contact between the intermediate electrode 104 and the insulating layer 401 of the lower electrode can be avoided. You can prevent it as well.
[0022]
(Example 5)
The fifth embodiment is another means for avoiding contact between the intermediate electrode 104 and the insulating layer 401 of the lower electrode. FIG. 7 is a cross-sectional view taken from 502 to 503 in FIG. The entire upper electrode is insulated and protected by the insulating layer 401. When a potential difference is generated between the lower electrode 101 and the intermediate electrode 104 and moves downward, the lower surface of the optical element 701 contacts the insulating layer 401 that insulates and protects the upper electrode 106 at a point 703. At this time, a gap 702 exists between the intermediate electrode 104 and the lower electrode insulating layer 401.
[0023]
In this way, contact between the intermediate electrode 104 and the insulating layer 401 of the lower electrode can be avoided, so that adverse effects such as adsorption can be prevented. In Example 5, the lower surface of the optical element is made of an insulator. However, even in the case of a conductor, contact between the intermediate electrode 104 and the insulating layer 401 of the lower electrode can be avoided. Can be prevented as well.
[0024]
(Example 6)
FIG. 8 shows a sectional view of an active microelement array of Example 6. Reference numeral 101 denotes a lower electrode provided on the lowermost surface of the actuator provided on the drive circuit. The spring 104 is supported by a support column 105 that supports the spring, and the other end is connected to the intermediate electrode. A part of the upper surface of the intermediate electrode has a connection portion 103 with a micro optical element. Above the intermediate electrode is an upper electrode 106 supported by a column. The micro optical element 901 according to the sixth embodiment has a reflection portion having a V-groove structure at the top. When a potential difference is generated between the lower electrode 101 and the intermediate electrode, it moves downward against the spring, and a gap of about 0.5 μm is generated between the light guide 802 and the micro optical element 801. In this state, the light beam 808 in the light guide unit is totally reflected on the bottom surface of the light guide unit and reflected in the direction of the light beam 807. On the other hand, when a potential difference is generated between the upper electrode 106 and the intermediate electrode, it moves upward against the spring, the bottom surface of the light guide 802 and the top surface of the micro optical element 801 are brought into close contact with each other, and the light beam 805 in the light guide is microscopic. It is possible to enter the optical element. Since the micro-optical element has a v-structure reflecting surface, incident light is reflected by the inclined surface and emitted as a light beam 806 perpendicular to the bottom surface of the light guide unit 802. In this way, by moving the micro optical element up and down by the microactuator provided at the lower part, the angle of light can be changed by about 70 degrees, and an optical switching operation can be obtained using this. When the bottom surface of the light guide 802 and the top surface of the micro optical element 801 are in close contact with each other, the contact between the insulating layer 401 on the upper electrode 106 and the intermediate electrode is avoided, and a gap 804 is left.
[0025]
As a result, even if a potential difference is generated between the upper electrode and the intermediate electrode and moves upward, the light guide 802 serves as a stopper, and contact between the insulator of the upper electrode and the intermediate electrode can be avoided. Therefore, adverse effects such as adsorption can be prevented in the same manner as in the case of the lower electrode.
[0026]
(Example 7)
FIG. 9 is a schematic view showing an image display apparatus in Embodiment 7 of the present invention. The light emitted from the light source 901 is condensed on the color filter 903 by the lens 902, becomes parallel light by the collimating lens 904, and enters the light introducing prism 906. The light incident on the light introducing prism 906 is incident on the active micro optical element array 905 described in the first to sixth embodiments, and is selectively emitted to the pixel 907 as a pixel display. Light 907 having image information is projected onto a screen by a projection lens 908 to display a moving image or the like. As described above, since a very small micro optical element array is realized, a small and bright image display apparatus with a very small number of parts can be realized.
[0027]
【The invention's effect】
As described above, according to the present invention,
1) By using a single spring and a spring support mechanism in one place, even in an actuator having electrodes on the top and bottom, the area of the top and bottom electrodes can be increased, and at the same time, the coupling portion with the micro optical element can be increased. The joining area was also large. This dramatically improves the space utilization efficiency and simultaneously resolves the conflicting issues of reducing the size of the micro optical element and reducing the energy input to the micro actuator that drives the micro optical element, The micro optical element can be made very small, and the electrical energy input to the actuator can be reduced.
[0028]
2) According to the microactuator of the present invention, the difference in the size of the upper and lower electrode areas was absorbed, and the upper and lower electrodes could be driven at the same voltage of 5V. Therefore, since the area of the drive circuit provided under the microactuator can be reduced, an effective means for a large-scale microactuator array can be obtained.
[0029]
3) According to the active micro-optical element of the present invention, the intermediate electrode does not even contact the insulating layer protecting the upper and lower electrodes, and accumulates in the intermediate electrode for every single vertical drive of the micro-optical element. Therefore, it can be used in devices such as printers and image display devices that have a very large number of optical switching operations.
[0030]
4) By using an active micro optical element array for an image display device, a more power-saving image display device can be realized and one image display device can be made smaller. Even the display element is 0.9 inches or less, and the number of image display elements that can be taken from one silicon wafer has been dramatically improved.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating an actuator unit according to a first embodiment.
FIG. 2 is a schematic diagram showing a cross-sectional view of FIG. 1;
FIG. 3 is a schematic diagram illustrating an actuator unit according to a third embodiment.
4 is a schematic diagram showing a cross-sectional view of FIG. 3. FIG.
FIG. 5 is a schematic diagram illustrating an actuator unit according to a fourth embodiment.
6 is a schematic diagram showing a cross-sectional view of FIG. 5. FIG.
7 is a schematic diagram showing a cross-sectional view of FIG. 5 in Example 5. FIG.
8 is a cross-sectional view of an active microelement array of Example 6. FIG.
FIG. 9 is a schematic diagram illustrating an image display apparatus according to a seventh embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 101 ... Lower electrode 102 ... Intermediate electrode 106 ... Upper electrode 201 ... Space between upper electrode and intermediate electrode 202 ... Space between lower electrode and intermediate electrode 203 ... Optical element 802 ... Light introducing portion 805 ... Incident light

Claims (5)

In an active micro optical element having a micro optical element and a micro actuator,
An intermediate electrode;
An upper electrode provided on the upper surface side of the intermediate electrode;
A lower electrode provided on the lower surface side of the intermediate electrode;
A coupling portion that is provided on the upper surface of the intermediate electrode and that couples the intermediate electrode and the micro-optical element positioned above the intermediate electrode;
The microactuator has a single spring support, and has a structure in which the intermediate electrode is supported by a single spring, and is coupled to the micro optical element by one or more coupling parts.
It has an actuator structure that moves the intermediate electrode by the applied voltage between the intermediate electrode and the lower electrode, or the upper electrode,
When the area of the lower electrode is larger than that of the upper electrode and the potentials of the lower electrode, the intermediate electrode, and the upper electrode are equal, the distance between the intermediate electrode and the lower electrode is greater than the distance between the intermediate electrode and the upper electrode. An active micro optical element characterized by being large. In an active micro optical element in which a micro optical element is coupled to a micro actuator and the micro optical element is moved by an electrostatically driven micro actuator having a drive circuit for each micro actuator.
An intermediate electrode;
An upper electrode provided on the upper surface side of the intermediate electrode;
A lower electrode provided on the lower surface side of the intermediate electrode,
When a potential difference occurs between the intermediate electrode and the lower electrode and the electrode moves downward, the bottom surface or part of the connection portion between the intermediate electrode and the micro optical element, or the bottom surface of the intermediate electrode is connected to the adjacent intermediate electrode. It is characterized in that it is stopped in contact with a part of a supporting pillar that supports a spring that is electrically conductive and in which the intermediate electrode and the supporting pillar connected to the adjacent intermediate electrode are in contact with each other. Active micro optical element. In an active micro optical element in which a micro optical element moves by an electrostatic drive type micro actuator having a driving circuit for each micro optical element, micro actuator,
An intermediate electrode;
An upper electrode provided on the upper surface side of the intermediate electrode;
Defining the downward movement of the intermediate electrode, and an upper electrode provided on the upper surface side of the intermediate electrode;
A lower electrode provided on the lower surface side of the intermediate electrode;
Provided on the upper surface of the intermediate electrode, and comprising a coupling portion for coupling the intermediate electrode and the micro optical element,
The coupling portion is made of a conductor or an insulator, and the bottom surface of the micro optical element is made of an insulator. When the potential difference is generated between the intermediate electrode and the lower electrode and the lower electrode moves downward, the top surface of the upper electrode An active micro-optical element, wherein the micro-optical element stops when a part or all of the lower surface of the optical element comes into contact. In the micro actuator, drive circuit, active micro optical element that has an intermediate electrode between the lower and upper electrodes, and the micro optical element connected to the intermediate electrode moves to perform optical switching operation.
When the micro optical element moves upward, the position of the micro optical element is defined by the light guide provided above the micro optical element, and when the micro optical element comes into contact with the light guide and stops, the intermediate electrode An active micro optical element characterized in that at least the entire upper surface (surface on the upper electrode side) and the lower surface of the upper electrode (surface on the intermediate electrode side) are not in contact with each other.   An arrayed optical switching element is formed by arraying the active micro optical elements according to any one of claims 1, 2, 3, and 4, and an image is displayed by the optical switching element array. Image display device.

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