JP3775155B2 - Optical switching device, optical switching unit, and image display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical switching device used for a video projection apparatus such as a data projector or a video projector or an image display device suitable for an image display apparatus, and an image display apparatus using the same.
[0002]
[Prior art]
As an image display device capable of controlling on / off of light as a light valve of an image display device such as a projector, a device using liquid crystal is known. However, the image display device using this liquid crystal has poor high-speed response characteristics and operates only at a response speed of about several milliseconds. For this reason, devices that display high-resolution images that require high-speed response, optical recording devices such as optical communication, optical computation, hologram memory, and optical printers are realized by switching devices that use liquid crystals. Is difficult.
[0003]
Accordingly, there is a need for a switching device or an image display device capable of high-speed operation that can be used for the above-described applications, and eagerly develops a switching device having a micro structure on the micron order or a smaller submicron order. It is being advanced.
[0004]
[Problems to be solved by the invention]
One is to extract the evanescent light by bringing the extraction surface of the optical element into contact with the total reflection surface of the light guide (light guide), which is filed by the applicant of the present application and capable of transmitting light by total reflection. It is an optical switching device that can modulate and control light at high speed by a minute movement of an optical element of about one wavelength or less.
[0005]
FIG. 1 shows an outline of a projector 80 as an example of an image display device using an image display device (optical switching device) that performs switching by evanescent light. The projector 80 includes a white light source 81, a rotary color filter 82 that splits the light from the white light source 81 into three primary colors and makes the light incident on the light guide plate (light guide) 1 of the image display unit (light switching unit) 55, An image display unit 55 that modulates and emits light of each color and a projection lens 86 that projects the emitted light 85 are provided. Then, the modulated light 85 for each color is projected onto the screen 89 and mixed with time to output a multi-tone multicolor image. The projector 80 further includes a control circuit 84 that controls the image display unit 55 and the rotating color filter 82 to display a color image. The image display unit 55 includes a light guide 1 and an image display device (light switching device) 50 described in detail below. Data φ for displaying a color image from the control circuit 84 is an image display device. 50.
[0006]
The image display unit 55 includes a trapezoidal prism-shaped light guide 1 having a surface 1b for receiving or entering light. In the projector 80 shown in FIG. 1, the light is projected onto the incident surface 1b of the light guide 1. Means for inputting / outputting light including a light source 81 for supplying light for light and a lens 85 for projecting light emitted from the light guide 1, and the projection light supplied to the light guide 1 for total reflection surface 1a. And an image display device 50 that modulates the image. The image display device 50 controls the evanescent light leaking from the light guide 1 to display an image.
[0007]
FIG. 2 shows an outline of an image display device (evanescent light switching device) 50 that modulates light using evanescent waves (evanescent light). The image display device 50 is a switching device in which a plurality of optical switching elements (optical switching mechanisms) 10 are two-dimensionally arranged. Each of the optical switching elements 10 is a light guide plate capable of transmitting incident light 2 by total reflection. An optical element (switching unit) 3 capable of modulating light by approaching and moving away from the (light guide) 1 and an actuator 6 for driving the optical element unit 3 are provided. Then, the layer of the optical element 3 and the layer of the actuator 6 are stacked on the semiconductor substrate 20 on which the drive circuit for driving the actuator 6 and the digital storage circuit (storage unit) are built, and are integrated as one image display device. Has been.
[0008]
The image display device 50 of this example using evanescent light will be described in more detail with reference to FIG. Describing based on the individual optical switching elements 10, the optical switching element 10a shown on the left side of FIG. 2 is in the on state, and the optical switching element 10b shown on the right side is in the off state. The optical element 3 extracts a surface (contact surface or extraction surface) 3a that is in close contact with the total reflection surface 1a of the light guide 1 and an evanescent wave that leaks when the surface 3a is in close contact with the total reflection surface 1a. Are provided with a V-shaped reflecting prism (microprism) 4 that reflects in a direction substantially perpendicular to the light guide plate 1 and a support structure 5 that supports the V-shaped prism 4.
[0009]
The actuator 6 shown in FIG. 2 is of a type that electrostatically drives the optical element 3. For this purpose, an upper electrode 7 that is mechanically connected to the support structure 5 of the optical element 3 and moves together with the optical element 3, A lower electrode 8 fixed to the semiconductor substrate 20 at a position facing the electrode 7 is provided. Further, the upper electrode 7 is supported by a support column 11 extending upward from the anchor plate 9, and the upper electrode 7 is mechanically attached to the uppermost surface 20 a of the semiconductor substrate 20 via the anchor plate 9. Therefore, when different voltages are supplied to the upper electrode 7 and the lower electrode 8, the upper electrode 7 moves downward, and the optical element 3 moves away from the light guide 1 in conjunction with this (second position). On the other hand, the upper electrode 7 partially has a function as an elastic member. When the voltage supplied to the upper electrode 7 and the lower electrode 8 is removed, the upper electrode 7 is separated, and the elasticity of the upper electrode 7 makes the optical The element 3 is in close contact with the total reflection surface 1a of the light guide 1 (first position).
[0010]
As shown in FIG. 1, the light guide 1 has a trapezoidal shape, and illumination light (incident light) 2 incident perpendicularly to the incident surface 1b is transmitted at an angle at which it is totally reflected by the total reflection surface 1a. Therefore, light is repeatedly totally reflected at all the interfaces inside the light guide 1, that is, the side 1 a facing the optical element 3 and the upper surface (outgoing surface), and the light guide plate 1 is filled with light. In this state, the illumination light 2 is macroscopically confined inside the light guide plate 1 and propagates through it without loss. On the other hand, microscopically, in the vicinity of the totally reflecting surface 1a of the light guide plate 1, the incident light 2 once leaks from the light guide plate 1 by a very small distance of the wavelength of light, and the course is changed. The phenomenon of returning to the inside of the light guide plate 1 again occurs. The light leaking from the surface 1a is generally called an evanescent wave. This evanescent wave can be extracted by bringing the optical element closer to the total reflection surface 1a at a distance of about the wavelength of light or less. The optical switching element 10 of this example is designed for the purpose of modulating, that is, switching (on / off) the light transmitted through the light guide plate 1 at high speed using this phenomenon.
[0011]
In the optical switching element 10a of FIG. 2, the optical element 3 is pressed against the total reflection surface 1a of the light guide plate 1, and the extraction surface 3a approaches or comes into close contact with the total reflection surface 1a. Can be extracted. For this reason, the angle of the light 2 is changed by the microprism 4 of the optical element 3 to become the outgoing light 2a, which is used as the projection light 85 of the projector 80 shown in FIG.
[0012]
On the other hand, in the optical switching element 10b, since the electrostatic force acts on the electrodes 7 and 8, the optical element 3 is moved to the second position away from the total reflection surface 1a. Therefore, no evanescent wave is extracted by the optical element 3, and the light 2 is reflected by the total reflection surface 1 a and does not exit from the inside of the light guide 1.
[0013]
An optical switching element using an evanescent wave functions as a device capable of switching light alone, but as shown in FIG. 2, a configuration in which these can be arranged side by side in a one-dimensional or two-dimensional direction, or even in a three-dimensional manner. It has become. In particular, it is possible to provide an image display device 50 and an image display unit 55 that can display a two-dimensional image in the same manner as a liquid crystal or DMD by arranging them in a two-dimensional matrix or array. In the image display device 50 using evanescent light, the moving distance of the optical element 3 serving as a switching unit is on the order of submicrons, so that it can be used as a light modulation device having a response speed one digit or more faster than that of liquid crystal. It is possible to provide a projector 80 or a direct-view type image display device capable of high-speed operation using the. Furthermore, the optical switching element 10 using evanescent light can turn on and off light almost 100% with submicron order motion, and can express a very high contrast image. For this reason, it is easy to increase the temporal resolution, and a high-contrast image display apparatus can be provided.
[0014]
Further, in this optical switching device 50, the image display device 50 having a configuration in which the actuators 6 and the optical elements 3 arranged in an array are stacked on the semiconductor integrated substrate 20 on which a drive circuit and the like are built is provided in one chip. It is possible. That is, the image display unit 55 can be supplied by assembling the image display device 50 and the light guide 1 which are a micromachine or an integrated device in which a microstructure such as the actuator 6 and the optical element 3 is constructed on the semiconductor substrate 20. By incorporating the projector, it is possible to provide a projector capable of displaying a high-contrast image with high operation speed and high resolution.
[0015]
The actuator 6 for configuring a switching device using evanescent light is not limited to the one having the upper and lower electrodes in FIG. 2, but in addition to the upper electrode 7 and the lower electrode 8, as shown in FIG. It is also possible to provide an intermediate electrode (movable electrode) 51 that moves between them, and to drive the optical element 3 in conjunction with the intermediate electrode 51. The image display device 50 has an advantage that it can be driven at a low voltage although the configuration of the actuator 6 is complicated. Furthermore, instead of electrostatic actuators using electrode pairs, it is also possible to configure actuators using mechanisms that can supply driving force by other electrical signals such as piezo elements, and there are several types of actuators It is considered. Therefore, in the following description, for the sake of simplicity, description will be made based on an electrostatic drive type actuator having upper and lower electrodes, but the configuration of the actuator is not limited to this.
[0016]
Thus, the optical switching device using evanescent light can be driven at high speed, and further has a configuration in which microactuators and microoptical elements are arranged in an array on a semiconductor substrate. Therefore, it can be provided as a device or unit for displaying an image with a very compact, high resolution and high contrast. However, it is necessary to guide the incident light at a suitable angle with respect to the total reflection surface with a small loss, and the shape and size of the light guide are determined based on these requirements. Therefore, the light guide 1 is larger than the image display device 50 that is a semiconductor chip. For example, when the light is reflected a plurality of times by the total reflection surface 1a with which the switching device 50 is in contact, the light extracted by the optical element does not reach the rear optical switching element. Therefore, it is necessary to set the incident surface 1b so that the incident light is incident on the entire area with which the switching device 50 is in contact, or light is not reflected by the total reflection surface 1a. For this reason, as the light guide 1, a polyhedral prism such as a trapezoidal prism having a sufficient thickness with respect to the semiconductor chip serving as the switching device 50 is suitable. Further, as a member that forms an optical system that receives light from the light source 81 and emits projection light to the projection lens 86, a prism having an appropriate size that is easy to assemble and adjust is desirable.
[0017]
Therefore, the light guide 1 becomes relatively large with respect to the image display device 50, and some problems to be solved arise when combining them. First, in an image display unit using evanescent light, the optical element 3 serving as a switching unit needs to be in close contact with the total reflection surface 1 a of the light guide 1. On the other hand, when the image display device is assembled so as to be in close contact with the light guide, a space for wiring to the connection electrode prepared in the image display device cannot be secured. That is, in an image display device in which optical switching elements are arranged in an array, a row driver or a column driver is built in to drive each actuator. Although it is necessary to supply a signal, it is not possible to secure a bonding space.
[0018]
The image display device is in a state where an actuator and an optical element are stacked on a semiconductor substrate. In order to protect the optical element and the like, it is desirable to stack a light guide at an early stage after being formed into a chip. However, it is difficult to immediately mount the chip at a predetermined position of the large prism, and there is a problem in storage or distribution even if it is possible. Furthermore, it is desirable to reduce the space of the optical element that is an actuator or a switching element. For this purpose, it is inconvenient to handle that a large prism must be bonded to a chip that is an image display device.
[0019]
Therefore, in the present invention, in a switching device using evanescent light in which a microactuator and a micro optical element are stacked on a substrate, the switching device that can solve these mounting problems and an image using the switching device An object of the present invention is to provide a display unit and an image display device.
[0020]
[Means for Solving the Problems]
For this reason, in the present invention, a large prism is not directly mounted on a device in which a microactuator and a micro optical element are laminated on a substrate. To solve the problem. That is, the optical switching unit using evanescent light of the present invention transmits incident light to a substrate, at least one driving actuator disposed on the substrate, an optical element driven by the actuator. A light guide having a total reflection surface, wherein the optical element is driven by the actuator to a position where the optical element extracts evanescent light and a position where the evanescent light is not extracted. Among them, it is characterized in that it has a shape that protrudes in the direction of the substrate with respect to the main body having a surface that can receive light from an external light source, and has a connection body that has a total reflection surface facing the optical element. .
[0021]
By providing the light guide with a connection body that protrudes from the main body in addition to the main body, a mounting space used for wire bonding or the like can be secured between the main body and the substrate. Furthermore, it becomes possible to provide an optical switching device in which the connection body is joined to the main body later until the joint body is combined with the substrate, the actuator, and the optical element. In other words, the present invention includes a substrate, at least one driving actuator disposed on the substrate, and an optical element driven by the actuator, and includes a total reflection surface that transmits incident light. An optical switching device in which the optical element is driven by the actuator to a position where the evanescent light is extracted and a position where the evanescent light is not extracted by the actuator with respect to the total reflection surface of the light guide. It is possible to provide an optical switching device having a connection body including a total reflection surface facing an optical element, which has a shape protruding in the direction of the substrate with respect to a main body having a smooth surface. Since it is not necessary to provide an incident surface, the connection body can be made thinner and more compact than the light guide body. Therefore, the optical switching device in which the connection body is combined with the substrate, the actuator, and the optical element is compact and thin. Further, if the connection body is combined, the actuator and the optical element are protected by the connection body. As it becomes easier to handle.
[0022]
In addition to the connection body and the substrate, by providing a side wall that surrounds the actuator and the optical element, it is possible to seal the space in which the actuator and the optical element are arranged, and the decompression process can be performed in a device state that does not include the main body. . Also, handling becomes flexible, such as shipping in the state of the device, or replacing the device with the main body fixed to the apparatus.
[0023]
When a connection body having a shape protruding from such a main body is provided, the side surface of the connection body does not become a total reflection surface, so that incident light leaks from this surface and light utilization efficiency decreases. Further, the leaked light becomes stray light and causes a decrease in contrast. Therefore, it is desirable to form a reflective film on the side surface of the connection body. Further, when a sealing side wall is provided so as to surround the actuator and the optical element, light leaks because a region connected to the side wall of the connection body facing the optical element is not a total reflection surface. Therefore, by forming a reflective film also in this region, light utilization efficiency can be improved and stray light can be prevented.
[0024]
The height of the side wall is determined so that the space between the substrate and the total reflection surface secures a displacement for pressing the optical element against the total reflection surface by the actuator. For this reason, when the reflective film is formed, it is necessary to set the thickness of the side wall in consideration of the film thickness.
[0025]
In addition, if a low melting point metal film is formed on the surface of the side wall that is in contact with the reflective film, the reflective film having a lower hardness than glass or the like is fused or brought into contact with the metal film, so that airtightness can be easily ensured. Therefore, it is possible to easily provide an optical switching device and an optical switching unit in which a space constituted by the substrate, the side wall, and the connection body is sealed under reduced pressure.
[0026]
Further, since a bonding space is secured by providing a connection body, it is not necessary to arrange a connection electrode on the back side of the substrate, and an electrode for supplying a drive signal to the actuator is disposed outside the side wall. Can do. Therefore, the wiring of the substrate can be simplified, and a low-cost optical switching device or unit can be provided.
[0027]
Furthermore, the present invention can also be applied to a device or unit in which an optical switching element based on a combination of an actuator and an optical element is arranged alone, but the optical switching device or unit in which the actuator and the optical element are arranged in an array. The present invention can also be applied to. A device or unit in which these optical switching elements are arranged in an array can be used as an image display device, a device for an optical computer, a device for an optical printer, or the like. Can provide. Therefore, it is possible to provide an image display device having an optical switching unit and means for inputting / outputting display light to / from the main body of the optical switching unit.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be further described below with reference to the drawings. FIG. 4 shows an outline of an image display unit (evanescent light switching unit) 55 that modulates light using an evanescent wave (evanescent light) according to the present invention. The switching unit 55 has a two-dimensional optical switching element 10 composed of a combination of the actuator 6 and the optical element 3 capable of extracting evanescent light with substantially the same configuration as the optical switching unit 55 described above with reference to FIGS. The detailed description of the actuator 6, the optical element 3 which is a switching unit, and the optical switching element 10 is omitted.
[0029]
The optical switching unit 55 of this example is composed of a substantially trapezoidal main body 60 and a connecting body 61 that extends or protrudes from the main body 60 toward the substrate 20 in order to transmit incident light 2. Yes. A main body (hereinafter referred to as a trapezoidal prism) 60 includes a surface 1b on which incident light 2 is incident, a surface 1c to which a connection body 61 is connected, and an exit surface 1d parallel to the surface 1c. Further, a reflection film 62 is formed on the surface 1e facing the incident surface 1b, and the incident light 2 is not leaked to the outside from the surface 1e. Further, the surface 1c and the exit surface 1d in contact with the connection body 61 are total reflection surfaces with respect to the incident light 2, and the incident light 2 is not emitted from these surfaces. Guided to the connection body 61.
[0030]
The connection body 61 is a substantially plate-like prism made of an optical material having the same refractive index as that of the trapezoidal prism 60. The upper surface 61a serves as a contact surface with the trapezoidal prism 60, and the lower surface 61b parallel to the upper surface 61a It is the total reflection surface 1a which reflects and transmits. The optical elements 3 constituting the optical switching element 10 facing the total reflection surface 1 a are arranged in an array and are driven by the actuator 6. Therefore, the evanescent light extracted from the total reflection surface 1 a to the optical element 3 is reflected by the optical element 3 to become outgoing light 2 a, and passes through the connecting body 61 and the trapezoidal prism 60 to the outside from the outgoing surface 1 d of the trapezoidal prism 60. Released.
[0031]
As described above, in the optical switching unit 55 of this example, the light guide 1 is constituted by the trapezoidal prism 60 and the connecting body 61, so that the connecting body 61 is separated from the trapezoidal prism 60 and the optical element 3 and the substrate 20 are separated. It can be provided as a device that sandwiches the space in which the actuators 6 are arranged. FIG. 5 shows the optical switching device 50 in this state. In this optical switching device 50, the microstructure comprising the actuator 6 and the optical element 3 constructed on the semiconductor substrate 20 is sealed by the connecting body 61, that is, the connecting body 61 is used for sealing. It is a prism and is stable. Therefore, it can be stored or distributed in this state. Furthermore, it is possible to package the substrate 20 and the connecting body (hereinafter referred to as a sealing prism) 61 with an appropriate molding resin or the like, and it can be stored and distributed in a more stable state.
[0032]
In the optical switching unit 55 and the device 50 of this example, the semiconductor substrate 20 further spreads outside the sealing prism 61, and bonding region is formed in the region of the surface 20 a of the semiconductor substrate located outside the sealing prism 61. A pad 71 is disposed. In the optical switching unit 55 of this example, a suitable space corresponding to the thickness of the sealing prism 61 can be secured between the trapezoidal prism 60 and the semiconductor substrate 20 by the sealing prism 61. Therefore, a space for wiring is set above the bonding pad 71, and the bonding wire 72 can be easily connected and wired to an external substrate or the like.
[0033]
Therefore, it is desirable to set the thickness of the sealing prism 61 to such an extent that a space for wiring can be secured. However, if the sealing prism 61 is thick, the incident light 2 leaks from the side surface 61c of the sealing prism 61 as indicated by a broken line 91 in FIG. Therefore, in the optical switching device 50 of this example, the reflection film 63 is formed on the side surface 61c of the sealing prism 61 to prevent light from leaking out. The sealing prism 61 of this example is a prism or cylinder whose side surface 61c extends in the vertical direction with respect to the total reflection surface 1a. For this reason, the light reflected by the reflective film 63 on the side surface does not change the angle with respect to the total reflection surface 1a, and can be modulated by the optical element 3 or the optical switching element 10 disposed facing the total reflection surface 1a. Become light.
[0034]
Furthermore, in the optical switching device (image display device) 50 of this example, a side wall 75 is formed so as to surround a region where the optical element 3 and the actuator 6 are arranged as shown in an enlarged view in FIG. Therefore, the space 29 in which the actuator 6 and the optical element 3 are arranged is shielded or sealed by the side wall 75, the substrate 20, and the sealing prism 61. Therefore, it is possible to make a hole in a part of the side wall 75 to reduce the pressure inside the space 29. If the inside of the space 29 is sealed, the space 29 in which the actuator 6 and the optical element 3 move can be held in a reduced pressure state. When the pressure is reduced, the air resistance when the optical element 3 is driven can be suppressed, so that the operation speed can be further increased, and the load on the actuator 6 can be reduced.
[0035]
In consideration of the process of reducing the pressure, in the optical switching unit 55 of this example, the substrate 20 is covered with the sealing prism 61 and can be separated from the main body 60 of the light guide 1. Therefore, it is easy to put in a vacuum chamber or the like when decompressing, and it is easy to handle. Since the sealing prism 61 maintains airtightness, it can be stored and distributed as it is.
[0036]
When such a side wall 75 is provided, the region where the total reflection surface 1a of the sealing prism 61 and the side wall 75 are connected to each other is not a total reflection surface. As shown by a broken line 92 or 93 in FIG. Leakage or irregular reflection. Therefore, the region to which the side wall 75 is attached becomes light and bright due to irregularly reflected light or stray light, which causes a decrease in contrast when an image is displayed by the optical switching unit 55 of this example.
[0037]
For this reason, in the optical switching device 50 of this example, as shown in an enlarged view in FIG. 6, the reflective film 64 is provided in the surrounding region 61d in contact with the side wall 75 in the total reflection surface 1a in the same manner as the side surface 61c. It is formed. Accordingly, there is no light leaking from the side wall 75 or irregular reflection, so that the light use efficiency can be increased and an image with high contrast can be displayed at the same time. These reflective films 63 and 64 can be formed by vapor deposition or sputtering of a metal such as aluminum. It is also possible to form a film having an appropriate reflectivity by stacking a plurality of thin films having different refractive powers.
[0038]
When the space 29 between the substrate 20 and the sealing prism 61 is sealed with the side wall 75, sealing at the upper and lower boundaries of the side wall 75 becomes a problem. The side wall 75 can be formed by molding a resin on the surface 20a of the semiconductor substrate 20 in the same manner as the optical element 3 or simultaneously. Therefore, the sealing degree of the boundary region with the substrate 20 is very high. On the other hand, since the surface in contact with the sealing prism 61 is joined to the reflective film 64, it is difficult to increase the sealing degree. For this reason, in this example, a low melting point metal or soft metal film 76 such as a gold alloy or solder plating is formed on the upper surface of the side wall 75, and the sealing prism 61 is laminated. The reflective film 64 and the metal layer 76 are fused or adhered. Therefore, the optical switching device 50 of this example can easily seal the region or space 29 in which the optical element 3 and the actuator 6 move, and can also have a sufficiently high sealing performance. For this reason, the optical switching device (image display device) 50 and the optical switching unit 55 which can hold | maintain in the state which pressure-reduced the inside and exhibit the stable drive performance over a long period of time can be provided.
[0039]
Furthermore, the side wall 75 has a function of defining a distance h between the surface 20a of the semiconductor substrate 20 and the total reflection surface 1a of the sealing prism 61 as shown in FIG. This distance h is a distance by which the optical element 3 can be moved by the actuator 6 to a position where the evanescent light leaking from the total reflection surface 1a is not extracted. At the same time, the distance must be such that the optical element 3 can be brought into close contact with the total reflection surface 1a by the actuator 6. In order to bring the extraction surface 3a of the optical element 3 into close contact with the total reflection surface 1a in a stable state, it is desirable to drive the optical element 3 so that the extraction surface 3a presses the total reflection surface 1a. In the electrostatic actuator 6 of this example, when the upper electrode 7 which is a movable electrode is viewed as an elastic body, the entire surface 20a of the substrate and the entire surface thereof are balanced with respect to a distance where the elastic force is balanced with respect to the weight of the optical element 3 and the like. A predetermined displacement is maintained by reducing the distance h from the reflecting surface 1a. Therefore, the optical element 3 is pressed against the total reflection surface 1a by the elastic force of the upper electrode 7, the adhesion is good, and the evanescent light extraction efficiency is high. For this reason, when the reflective film 64 is provided on the total reflection surface 1a and the metal film 76 is provided on the side wall 75, the height of the side wall 75 can be held by the displacement of the upper electrode 7 in consideration of these film thicknesses. The optical switching device 50 of this example is also designed as such.
[0040]
As described above, the optical switching device 50 of this example includes the substrate 20, the layer of the actuator 6, the layer of the optical element 3 serving as a switching unit, and the sealing that serves as a connection body with respect to the main body 60 of the light guide 1. A prism 61 is stacked. Therefore, since the micromachine layer of the actuator 6 and the optical element 3 formed on the substrate 20 is covered with the sealing prism 61, it can be stored or distributed in this state. Moreover, it is possible to wire-bond to the connection electrode facilitated on the semiconductor substrate 20, and it is easy to mount.
[0041]
In particular, by enclosing the outside of the actuator 6 and the optical element 3 with the side wall 75, the empty fist 29 in which the actuator 6 and the optical element 3 move can be sealed under reduced pressure, and the performance of the optical switching device 50 can be improved. In addition, since the sealing prism 61 is connected and sealed under reduced pressure and can be shipped and distributed in that state, the performance of the product is stabilized, the yield of the optical switching device can be improved, and the cost can be reduced. Further, since the bonding pad 71 for connection can be arranged and wired in the region outside the side wall 75, it is possible to prevent the actuator or the optical element from being affected when wiring. Therefore, when the image display device as described with reference to FIG. 1 is configured using the optical switching device and the optical switching unit according to the present invention, the mounting can be easily performed, so that the cost can be further reduced. Since the utilization efficiency is high and the contrast can be increased, an image display device with good image quality can be provided. In the maintenance, the trapezoidal prism 60 constituting the optical system inside the apparatus is left as it is, and only the optical switching device 55 serving as an image display device can be replaced.
[0042]
Instead of separating the sealing prism 61 from the main body 60 of the light guide 1 so that it can be connected later, the light guide 1 can be laminated on the layer of the optical element 3 with the connecting portion 61 extended. In this configuration, a sufficient space can be secured for bonding. However, the trapezoidal prism having the incident surface is stored and distributed in an integrated state, and when the pressure is reduced, it is necessary to put the trapezoidal prism including the trapezoidal prism into the decompression chamber. Accordingly, the unit to be distributed or stored becomes large, and handling becomes difficult as compared with the device including the sealing prism 61 described above.
[0043]
In the above example, a trapezoidal prism is used as the main body 60 of the light guide 1. However, the trapezoidal prism is not limited in relation to the direction of incident light. It is only necessary to be able to guide incident light to the total reflection surface 1a at an angle that allows total reflection. For example, a parallelogram prism is adopted as the main body of the light guide so that light can be incident from the same side as the semiconductor substrate. Is also possible.
[0044]
Further, although a flat optical member is employed as the sealing prism constituting the connection body, the upper surface may be a triangular prism or the like, and the light guide body and polyhedron may be combined. However, in the case of the sealing prism of this example, the planes may be connected to each other. However, since it is necessary to join two or more surfaces, an optical member with higher accuracy is required. On the other hand, since the strength of the joint portion increases, the strength as the optical switching unit can also be increased.
[0045]
Furthermore, in this example, an optical switching device including an optical element unit as a switching unit is described as an example. However, the actuator is not limited to the one using the electrode pair of this example and using an electrostatic force. A type in which an optical element is driven using another piezoelectric element or the like may be used.
[0046]
【The invention's effect】
As described above, the light switching unit of the present invention is a unit that can output an image or the like by switching the evanescent light leaking from the total reflection surface of the light guide. By making the shape into a shape including a connection body extending toward the switching device, the optical switching device can be easily bonded. Furthermore, when the connection body is manufactured separately from the main body of the light guide and joined later, it is a compact device convenient for assembly, storage and distribution, and the micro structure such as the actuator and the optical element is protected by the cover. Can be realized.
[0047]
Furthermore, by providing the side wall, the space where the actuator and the optical element between the connection body and the substrate are arranged can be sealed and depressurized. And it can prevent that light leaks from a connection body by forming a reflection film in the side surface of a connection body, or forming a reflection film also in the surface which contacts a side wall. Therefore, an optical switching device that can be used in the field of optical switching or other optical switching, which can display an image with high driving performance and high contrast in a form that is easy to handle in the manufacturing, storage, mounting and distribution processes, An optical switching unit can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of a projector using an image display device using evanescent light.
FIG. 2 is a diagram showing an outline of an image display device (optical switching device) using evanescent light.
FIG. 3 is a diagram showing a different example of an optical switching device using evanescent light.
FIG. 4 is a diagram showing an outline of an optical switching unit according to the present invention.
5 is a diagram showing an outline of an optical switching device used in the optical switching unit of FIG. 4;
6 is an enlarged view of a peripheral portion of the optical switching device shown in FIG.
[Explanation of symbols]
1 Light guide plate (light guide)
2 Illumination (incident) light
2a Outgoing light
3 Optical elements
4 Microprism
5 V type support structure
6 Actuator
7 Upper electrode and spring structure
8 Lower electrode
9 Anchor
10 Optical switching element
11 Post (support)
20 Semiconductor substrate
29 Space where actuator and optical element are arranged
50 Image display devices
55 Image display unit
60 Light guide body (trapezoidal prism)
61 Light guide connector (sealing prism)
62, 63, 64 Reflective film
71 Bonding pads (connection electrodes)
72 Bonding wire
75 side walls
76 Metal film for sealing
80 projector

Claims (6)

A substrate, at least one driving actuator disposed on the substrate, and an optical element driven by the actuator;
An optical switching device in which the optical element is driven to a position where the optical element extracts evanescent light and a position where the evanescent light is not extracted by the actuator, with respect to the total reflection surface of the light guide including a total reflection surface that transmits incident light,
Of the light guide, a shape that protrudes in the direction of the substrate with respect to a main body having a surface that can receive light from an external light source and an exit surface that is parallel to the total reflection surface is formed on the optical element. The total reflection surface facing, a connection body smaller than the substrate;
Sidewalls arranged to surround the actuator and the optical element;
The substrate;
An optical switching device that is sealed under reduced pressure. In claim 1, a reflective film is formed in a region connected to the side surface of the connecting body and the side wall facing the optical element,
A low melting point metal film is formed on a surface of the side wall that is in contact with the reflective film,
The height of the said side wall is an optical switching device which considered the film | membrane pressure of the said reflecting film so that the displacement for pressing the said optical element to the said total reflection surface with the said actuator may be ensured.   3. The optical switching device according to claim 1, wherein an electrode for supplying a drive signal to the actuator is disposed outside the side wall of the substrate.   4. The optical switching device according to claim 1, wherein the actuator and the optical element are arranged in an array.   An optical switching unit comprising the optical switching device according to claim 1 and the light guide.   6. An image display device comprising: the optical switching unit according to claim 5; and means for inputting and outputting display light to and from the main body of the optical switching unit.

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