JP4380295B2 - Reflective liquid crystal display element and image projection apparatus - Google Patents

Description

  The present invention relates to a reflection type liquid crystal display element having a reflection type pixel electrode and an image projection apparatus such as a reflection type liquid crystal projector that displays an image using the reflection type liquid crystal display element.

  In recent years, as the resolution of projection displays has increased in size, size, and brightness, reflection-type devices that can be reduced in size and in definition and that can be expected to have high light utilization efficiency have been attracting attention and practical use. It has become. As a reflection type device, an active reflection type liquid crystal panel in which liquid crystal is injected between a pair of opposed substrates is known. In this case, as a pair of substrates, a transparent electrode substrate in which transparent electrodes are laminated on a glass substrate, and a drive element substrate utilizing a silicon (Si) substrate made of, for example, a CMOS (Complementary Metal Oxide Semiconductor) type semiconductor circuit; Is used. On the drive element substrate, a metal reflective pixel electrode for reflecting light and applying a voltage to the liquid crystal is disposed, thereby constituting the pixel electrode substrate as a whole. The reflective pixel electrode is made of a metal material mainly composed of aluminum, which is generally used in an LSI (Large Scale Integrate) process.

  In such a reflective liquid crystal panel, a voltage is applied to the liquid crystal by applying a voltage to the transparent electrode provided on the transparent electrode substrate and the reflective pixel electrode provided on the drive element substrate. . The liquid crystal to which the voltage is applied changes its optical characteristics according to the potential difference between the electrodes, and modulates the incident light. This modulation enables gradation expression and video display.

In the reflection type liquid crystal display provided with the reflection type liquid crystal panel as described above, the reflection type liquid crystal panel is conventionally cooled by a method such as natural heat dissipation or forced air cooling. However, it was difficult to say that an efficient cooling effect was obtained. In particular, the intensity of light incident on a reflective liquid crystal panel has been increasing in recent years. For this reason, the temperature of the reflective liquid crystal panel is remarkably increased, and the image projected on the screen may be deteriorated. In order to solve this problem, a reflective liquid crystal display is disclosed in which the drive element substrate of the reflective liquid crystal panel is integrated with a heat sink having heat radiating fins to improve the cooling efficiency (see, for example, Patent Document 1). .) In performing such integration, the drive element substrate side surface (surface opposite to the display surface) of the reflective liquid crystal panel and the heat sink are bonded using, for example, an adhesive tape or a paste-like adhesive. The method is common.
Japanese Patent No. 2871769

  However, the reflective liquid crystal panel integrated with the heat sink by the above-described bonding method may give distortion to the drive element substrate when used in a relatively wide temperature range. This is because the thermal expansion coefficients of the adhesive tape and adhesive, the heat sink, and the drive element substrate are different from each other, so that the amount of change in shape differs at a temperature different from the temperature at the time of bonding, resulting in the drive element. This is considered to cause distortion of the substrate. The distortion of the drive element substrate changes the slight thickness of the liquid crystal layer defined by the gap between the drive element substrate and the transparent electrode substrate. For this reason, the light intensity on the display surface becomes non-uniform, and as a result, it appears as uneven brightness in the projected image on the screen, resulting in deterioration of image quality. In addition, if the hardness of the adhesive is lowered to such an extent that distortion during such temperature changes does not occur, the reflective liquid crystal panel and the heat sink cannot be sufficiently fixed, and the optical axis is shifted. It is necessary to increase the hardness of the steel to some extent.

  The present invention has been made in view of such a problem, and a first object thereof is a reflective liquid crystal display which has a high cooling efficiency while having a simple and compact structure and does not cause distortion in a wider temperature range. It is to provide an element. A second object of the present invention is to provide an image projection apparatus that includes the above-described reflective liquid crystal display element and is capable of displaying an image with good image quality.

A reflective liquid crystal display device according to the present invention includes a display surface that displays an image by modulating and reflecting light from a light source in units of pixels based on an image signal, and a back surface and a display surface opposite to the display surface. A reflective liquid crystal panel having an end surface extending between the back surface, a support surface that contacts the back surface of the liquid crystal panel and supports the liquid crystal panel, and a portion of the support surface that corresponds to the liquid crystal panel a holding member having provided recess and the heat radiating portion provided on the opposite side of the support surface, is filled in contact with the rear surface of the liquid crystal panel in the recessed portion, the viscosity of minus 10 ° C plus 70 ° C In the temperature range, it is in the range of 100 to 1000 [Pa · s] and is provided with a thermally conductive filler having fluidity . Here, “contact with the back surface” means directly contacting the back surface of the liquid crystal panel without using an adhesive or the like. The “support surface” is usually formed to be a flat surface, but may be a curved surface. However, it is necessary to have at least three hitting portions (reference hitting portions). The planar shape of the “concave portion” is usually a rectangle, but may be other shapes (for example, a circle, an ellipse, an arbitrary polygon other than a rectangle, etc.). The “heat dissipating part” is a so-called heat sink, and is usually configured to have a large number of fins for increasing the contact area with air. The “thermally conductive filler” has only to be a property that has thermal conductivity and can be filled substantially following the shape of the container (in this case, the recess). It corresponds to a fluid material or a liquid material. Here, “thermal conductivity” means that the thermal conductivity is better than at least air.

An image projector according to the present invention includes a light source, a reflective liquid crystal display element that forms and displays an image corresponding to an image signal using light from the light source, and an image formed by the reflective liquid crystal display element. And a reflective liquid crystal display element that modulates and reflects light from the light source on a pixel-by-pixel basis based on an image signal and displays the image on the screen. Is a reflective liquid crystal panel having a back surface on the opposite side and a display surface and an end surface extending between the back surface, a support surface that contacts the back surface of the liquid crystal panel and supports the liquid crystal panel, and a liquid crystal among the support surfaces A holding member having a recess provided in a part of a region corresponding to the panel and a heat dissipating part provided on the opposite side of the support surface, and the recess is filled so as to contact the back surface of the liquid crystal panel , and its viscosity is negative. 10 ° C to plus 7 ° 100 to 1000 in the temperature range of C is in the range of [Pa · s], is obtained by so and a thermally conductive filler having fluidity.

  In the reflective liquid crystal display element and the image projector according to the present invention, a support surface that contacts the back surface of the liquid crystal panel and supports the liquid crystal panel, and a recess provided in a part of the support surface corresponding to the liquid crystal panel And a heat radiating portion provided on the opposite side of the support surface, the liquid crystal panel is held in a state where it is accurately placed at a predetermined position with respect to the holding member, No distortion due to expansion or thermal contraction. Furthermore, since the concave portion is provided with a thermally conductive filler filled so as to be in contact with the back surface of the liquid crystal panel, the heat generated by the light from the light source is efficiently transmitted from the heat radiating portion via the thermally conductive filler. Released.

  In the reflective liquid crystal display device according to the present invention, it is preferable that the reflective liquid crystal display device further includes an accommodating portion for accommodating an excess portion of the thermally conductive filler filled in the concave portion. Here, the “concave portion” is not a concept that means a portion including the “accommodating portion”, and the “concave portion” and the “accommodating portion” are separate. Although the position, shape, and size of the “accommodating portion” are arbitrary, it is necessary to communicate with the concave portion in order to accommodate the excess portion of the thermally conductive filler. “Excess portion” means the amount obtained by subtracting the total volume of the recess from the total filling amount of the heat conductive filler, in other words, the entire recess is supported in a state where it is completely filled with the heat conductive filler (no gap). The part which protrudes from a recessed part so that it may rise rather than a surface is meant. Furthermore, in the reflective liquid crystal display element according to the present invention, the end surface of the liquid crystal panel may be bonded to the support surface of the holding member with an adhesive at two or more locations. Alternatively, the holding member may further include a wall portion erected along the outer edge of the support surface, and the end surface of the liquid crystal panel may be bonded to at least the wall portion with an adhesive at two or more locations. Here, “two or more locations” means that at least two locations are sufficient, but preferably four locations. The “wall portion” does not have to be a continuous wall along the outer edge of the support surface, and may be provided at least at a location where it is bonded by an adhesive. “Adhering to at least the wall” means not only the case where the bonding partner of the end surface is only the wall, but also the case where both the wall and the support surface are included.

  According to the reflective liquid crystal display element and the image projector according to the present invention, a display surface that displays an image by modulating and reflecting light from a light source in units of pixels based on an image signal, and the side opposite to the display surface A reflective liquid crystal panel having a back surface, a display surface, and an end surface extending between the back surface, a support surface that supports the liquid crystal panel by contacting the back surface of the liquid crystal panel, and corresponds to the liquid crystal panel A holding member having a concave portion provided in a part of the region to be operated and a heat radiation portion provided on the opposite side of the support surface, and a heat conductive filler filled in the concave portion so as to contact the back surface of the liquid crystal panel. As a result, it is possible to suppress the occurrence of distortion of the liquid crystal panel due to thermal expansion and contraction during temperature changes while holding the liquid crystal panel in a state of being accurately arranged at a predetermined position with respect to the holding member. Light from the light source The heat generated more liquid crystal panels, can be efficiently released from the heat radiating portion via a thermally conductive filler.

  In particular, according to the image projection apparatus of the present invention, since the video display is performed using the reflective liquid crystal display element of the present invention, high image quality can be ensured.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  First, referring to FIG. 1, an image projection apparatus using a reflective liquid crystal display element according to an embodiment of the present invention will be described. FIG. 1 shows a schematic configuration of a reflective liquid crystal projector (hereinafter simply referred to as a liquid crystal projector) as an image projection apparatus using a reflective liquid crystal display element. As shown in FIG. 1, the liquid crystal projector according to the present embodiment is a so-called three-plate that performs color image display using three reflective liquid crystal display elements 21R, 21G, and 21B for red, green, and blue colors. It is of the method. The liquid crystal projector includes a light source 11, a PS converter 12, dichroic mirrors 13 and 17, and total reflection mirrors 14, 15 and 16 along the optical axis 10. The liquid crystal projector further includes polarizing beam splitters 18, 19, and 20, a cross prism 22 as color synthesizing means, and a projection lens 23 as projection means. Here, the PS converter 12, the dichroic mirrors 13 and 17, and the total reflection mirrors 14, 15 and 16 are one specific example corresponding to the “color separation means” of the present invention.

  The light source 11 emits white light including red light (R), blue light (B), and green light (G) required for color image display. For example, a halogen lamp, a metal halide lamp, or xenon is used. It is composed of lamps.

  The PS converter 12 functions to polarize and transmit light from the light source 11. Here, S-polarized light is transmitted as it is, and P-polarized light is converted to S-polarized light.

  The dichroic mirror 13 has a function of separating the light transmitted through the PS converter 12 into blue light and other color lights. The total reflection mirror 14 reflects the light transmitted through the dichroic mirror 13 toward the total reflection mirror 16, and the total reflection mirror 16 reflects the reflected light from the total reflection mirror 14 toward the dichroic mirror 17. ing. The dichroic mirror 17 has a function of separating light from the total reflection mirror 16 into red light and green light. The total reflection mirror 15 reflects the blue light separated by the dichroic mirror 13 toward the polarization beam splitter 20.

  The polarization beam splitters 18, 19, and 20 are disposed along the optical paths of red light, green light, and blue light, respectively. The polarization beam splitters 18, 19, and 20 have polarization separation surfaces 18A, 19A, and 20A, respectively, and the incident color lights are separated into two polarization components orthogonal to each other on the polarization separation surfaces 18A, 19A, and 20A. It has a function. The polarization separation surfaces 18A, 19A, and 20A reflect one polarization component (for example, S polarization component) and transmit the other polarization component (for example, P polarization component).

  The reflective liquid crystal display elements 21R, 21G, and 21B are configured to receive color light of a predetermined polarization component (for example, S polarization component) separated on the polarization separation surfaces 18A, 19A, and 20A. The reflective liquid crystal display elements 21R, 21G, and 21B are driven in accordance with a drive voltage applied based on an image signal, modulate incident light, and transmit the modulated light to the polarization beam splitters 18, 19, and 20. It functions to reflect towards. The reflective liquid crystal display elements 21R, 21G, and 21B will be described in detail later.

  The cross prism 22 synthesizes the color light of a predetermined polarization component (for example, P polarization component) that is emitted from the reflective liquid crystal display elements 21R, 21G, and 21B and transmitted through the polarization beam splitters 18, 19, and 20. The projection lens 23 projects the combined light emitted from the cross prism 22 toward a screen (not shown).

  Next, the configuration of the reflective liquid crystal display elements 21R, 21G, and 21B of the present embodiment will be described in detail with reference to FIGS. FIG. 2 shows a cross-sectional configuration of the reflective liquid crystal display elements 21R, 21G, and 21B. FIG. 3 shows a perspective configuration of the holding member 40 described later.

  As shown in FIG. 2, the reflective liquid crystal display elements 21R, 21G, and 21B are filled in the reflective liquid crystal panel 30, the holding member 40 that holds the liquid crystal panel 30, and a part of the holding member 40, respectively. The thermal conductive filler 50 is included. The holding member 40 is attached to the polarization beam splitters 18, 19, and 20 via a pedestal 60. The holding member 40 and the pedestal 60, and the pedestal 60 and the polarizing beam splitters 18, 19, and 20 are bonded and fixed to each other by solder, ultraviolet curable resin, or the like.

  The liquid crystal panel 30 includes a display surface 30A that displays an image by modulating and reflecting light from a light source in units of pixels based on an image signal, a back surface 30B opposite to the display surface 30A, and a display surface 30A. And an end face 30C extending between the back face 30B. The liquid crystal panel 30 includes a transparent electrode substrate 31 and a pixel electrode substrate 32 which are a pair of substrates disposed to face each other, and liquid crystal (not shown) injected between these substrates. A part of the surface of the transparent electrode substrate 31 opposite to the pixel electrode substrate 32 is a display surface 30A, and the surface of the pixel electrode substrate 32 opposite to the transparent electrode substrate 31 is a back surface 30B. End surfaces of the transparent electrode substrate 31 and the pixel electrode substrate 32 constitute an end surface 30C.

The transparent electrode substrate 31 includes a glass substrate and a transparent electrode formed on the pixel electrode substrate 32 side of the crow substrate. The transparent electrode is made of, for example, ITO (Indium Tin Oxide) which is a solid solution material of tin oxide (SnO ₂ ) and indium oxide (In ₂ O ₃ ) having a light transmitting action. A common potential (for example, ground potential) is applied to the transparent electrode in all pixel regions.

  The pixel electrode substrate 32 is provided with a reflective pixel electrode or the like on the liquid crystal side surface of a silicon substrate on which an active drive circuit composed of a transistor such as CMOS or NMOS and a capacitor is formed.

  As shown in FIGS. 2 and 3, the holding member 40 is in contact with the back surface 30 </ b> B of the liquid crystal panel 30 to support the liquid crystal panel 30, and the region of the support surface 41 corresponding to the liquid crystal panel 30. A recess 42 provided in a part and a heat radiating part 43 provided on the opposite side of the support surface 41 are provided. The support surface 41 is in contact with the back surface 30B at least at three locations without using an adhesive or the like, whereby the liquid crystal panel 30 is positioned. The recess 42 is a rectangular parallelepiped groove portion, and the inside thereof is filled with a heat conductive filler 50 so as to be in contact with the back surface 30 </ b> B of the liquid crystal panel 30. The heat generated in the liquid crystal panel 30 can be efficiently transferred to the heat radiating portion 43 via the thermally conductive filler 50. The heat dissipating part 43 releases heat from the heat conductive filler 50 into the air, and has a plurality of heat dissipating fins 44 to increase heat dissipating efficiency by increasing the contact area with air as much as possible. . Here, in order to increase the thermal conductivity, the recess 42 is desirably formed as shallow as possible in machining, for example, to a depth of about 0.1 mm.

  The thermally conductive filler 50 is preferably made of a fluid material having higher thermal conductivity such as silicone grease. This silicone grease is mainly composed of a mixture of silicone oil and a thickener such as a filler. When silicone grease is used as the thermally conductive filler 50, it is desirable that the viscosity be in the range of 100 Pa · s to 1000 Pa · s, particularly in the temperature range of −10 ° C. to 70 ° C. This is because if it exhibits such viscosity characteristics, it can be used in a wider temperature range. That is, when it exceeds 1000 Pa · s, the liquid crystal panel 30 that comes into contact with the liquid crystal panel 30 may be distorted, which may cause image quality deterioration due to luminance unevenness that becomes a problem in practical use. If it is less than s, the fluidity becomes too high, and there is a possibility that it will flow out to the display surface 30A side through the gap between the support surface 41 and the back surface 30B. In this case, if the viscosity is in the range of 100 Pa · s to 480 Pa · s, brightness unevenness is hardly observed, and a better image quality is obtained. “Viscosity” is also called viscosity, and is a material constant determined by the fluid. More specifically, for example, when the velocity u changes in the y direction in a fluid flowing parallel to the x axis, a tangential stress having a magnitude of η∂u / ∂y appears on a plane perpendicular to the y axis ( Newton's law of viscosity). This proportionality constant η is the viscosity. As the heat conductive filler 50, in addition to silicone grease, a gel material such as a heat conductive acrylic resin, or a fluid or semi-fluid material can be used. Alternatively, a liquid material such as silicone oil can be used. However, when a liquid material or a material with high fluidity is used, it is necessary to provide sealing for preventing the recess 42 from flowing out to the outside.

  The reflective liquid crystal display elements 21R, 21G, and 21B further include a storage portion 45 for storing an excess portion of the thermally conductive filler 50 filled in the recess 42. The accommodating portion 45 is not included in the concave portion 42 and is completely separate. In the manufacturing process, when the recessed portion 42 is filled with the heat conductive filler, generally, the supply amount slightly varies. For this reason, when the supply amount is larger than the total volume of the recess 42, the heat conductive filler overflows without being stored in the recess 42, the back surface 30B is separated from the support surface 41, and the liquid crystal panel 30 is floated. It will be. On the other hand, if the supply amount is slightly conserved to avoid this, the concave portion 42 cannot be sufficiently filled with the heat conductive filler, and the cooling efficiency is lowered as compared with the case where the concave portion 42 is at least completely filled. It becomes. For this reason, by providing the accommodating portion 45, the heat conductive filler 50 in an amount corresponding to the entire volume of the recess 42 can be filled relatively easily without a gap. That is, the supply amount may be at least equal to or greater than the entire volume of the concave portion 42 and the excess portion may be accommodated in the accommodating portion 45. Although the accommodating part 45 needs to communicate with at least the recessed part 42, the shape is not limited to what was shown in FIG. For example, as shown in FIG. 4, the holding member 40 is composed of two members, a frame member 40A and a heat radiating member 40B including the heat radiating portion 43, and several accommodating portions 45A are provided in the heat radiating member 40B. Also good. The accommodating portions 45 and 45A may be provided at only one place or at a plurality of places.

  Further, as shown in FIG. 5, the holding member 40 further includes a wall portion 46 erected along the outer edge of the support surface 41, and the end surface 30 </ b> C of the liquid crystal panel 30 has four adhesives 51 ( 51A to 51D) are bonded to the wall surface 46S of the wall portion 46. FIG. 5 shows a planar configuration of the reflective liquid crystal display elements 21R, 21G, and 21B. In FIG. 5, the number of places is four, but it is sufficient that at least two places are bonded to the wall 46 (wall 46 </ b> S) by the adhesive 51. The two or more locations may be, for example, two locations bonded in FIG. 5 by the adhesive 51A and the adhesive 51C, or may be bonded by the adhesive 51A, the adhesive 51B, and the adhesive 51C. It may be a place. In addition, “at least bonding with the wall 46 (wall 46S)” means not only the case where the bonding partner of the end face 30C is only the wall 46 but also both the wall 46 and the support surface 41 (supports 41A to 41D). It is meant to include some cases. The wall portion 46 does not have to be a continuous wall along the outer edge of the support surface, and may be provided at least at a location where the adhesive 51 is bonded. For example, in FIG. 5, four discontinuous wall portions 46 </ b> A to 46 </ b> D may be provided and bonded to the end surface 30 </ b> C with the corresponding adhesives 51 </ b> A to 51 </ b> D. In these cases, it is particularly desirable that the bonding location be located at an equal distance from the center C of the display surface 30A. That is, it is desirable that the distances D1, D2, D3, and D4 are all equal. By doing so, the stress is uniformly applied to the display surface 30 </ b> A, so that the occurrence of distortion in the liquid crystal panel 30 is suppressed. Here, “equal distance” does not necessarily mean completely equal distances, but includes a range that can be said to be substantially equidistant, for example, an error that may occur in a normal bonding process. Furthermore, it is desirable that the Shore hardness of the adhesive 51 after curing is in the range of 20 or more and 65 or less. If the Shore hardness is greater than 65, the distribution of the black illuminance (black level) of the liquid crystal panel 30 is biased. Conversely, if the Shore hardness is less than 20 and the hardness is insufficient, the liquid crystal panel 30 itself has its own weight. This is because the liquid crystal panel 30 is displaced. As the adhesive 51, for example, a UV curable resin in which an acrylic resin is a main component and an additive such as a polymerization reaction agent or a reaction accelerator is added thereto can be used. Shore hardness is defined by the JIS standard (Japanese Industrial Standard), and is a measure of the height of splash when a diamond hammer having a certain shape and weight is dropped vertically from a certain height onto the test surface. It is what.

  The operation and operation of the liquid crystal projector including the reflection type liquid crystal display elements 21R, 21G, and 21B configured as described above will be described. In this liquid crystal projector, white light emitted from the light source 11 and converted to, for example, S-polarized light by the PS converter 12 is first separated into blue light and other color lights (red light and green light) by the function of the dichroic mirror 13. The Of these, the blue light is reflected by the total reflection mirror 15 toward the polarization beam splitter 20. On the other hand, the red light and the green light are reflected toward the dichroic mirror 17 by the total reflection mirror 14 and the total reflection mirror 16, and then further separated into red light and green light by the dichroic mirror 17. The separated red light and green light are incident on polarization beam splitters 18 and 19, respectively.

  The polarization beam splitters 18, 19, and 20 separate each incident color light into two polarization components orthogonal to each other on the polarization separation surfaces 18A, 19A, and 20A. At this time, the polarization separation surfaces 18A, 19A, and 20A reflect one polarization component (for example, the S polarization component) toward the reflective liquid crystal display elements 21R, 21G, and 21B.

  The reflective liquid crystal display elements 21R, 21G, and 21B are driven according to a drive voltage given based on an image signal, and modulate incident color light of a predetermined polarization component in units of pixels. Specifically, first, incident light that has been incident from the transparent electrode substrate 31 side and transmitted through the liquid crystal is reflected by the reflection function of the reflective pixel electrode on the pixel electrode substrate 32. The light reflected by the reflective pixel electrode is transmitted through the liquid crystal and the transparent electrode substrate 31 in the opposite direction to the incident direction and emitted. At this time, the optical characteristics of the liquid crystal change depending on the potential difference between the opposing electrodes, that is, the potential difference between the transparent electrode in the transparent electrode substrate 31 and the reflective pixel electrode in the pixel electrode substrate 32, and the liquid crystal is transmitted. It modulates the light. At this time, since the liquid crystal panel 30 in the reflective liquid crystal display elements 21R, 21G, and 21B has almost no distortion due to thermal stress or due to adhesion to the wall surface 46S, the occurrence of uneven brightness on the display surface 30A is suppressed. .

  The reflective liquid crystal display elements 21R, 21G, and 21B reflect the modulated light toward the polarization beam splitters 18, 19, and 20, respectively. The polarization beam splitters 18, 19, and 20 transmit only a predetermined polarization component (for example, a P-polarization component) out of the reflected light (modulated light) from the reflective liquid crystal display elements 21 R, 21 G, and 21 B, and to the cross prism 22. Inject towards. The cross prism 22 combines the color lights of the predetermined polarization components that have been transmitted through the polarization beam splitters 18, 19, and 20 and emits the light toward the projection lens 23. The projection lens 23 projects the combined light from the cross prism 22 toward the screen. As a result, an image corresponding to the light modulated by the reflective liquid crystal display elements 21R, 21G, and 21B is projected onto the screen, and a desired image is displayed. At this time, it is possible to obtain a good image quality without deterioration due to luminance unevenness on the display surface 30A.

  As described above, the liquid crystal projector according to the present embodiment can display an image with good image quality. Conventionally, the surface opposite to the display surface has been structured to adhere to the heat dissipation part using adhesive tape or paste-like adhesive, etc. The pixel electrode substrate may be distorted at a temperature different from the above temperature. On the other hand, in the liquid crystal projector of the present embodiment, the reflective liquid crystal display elements 21R, 21G, and 21B each display an image by modulating and reflecting the light from the light source in units of pixels based on the image signal. A reflective liquid crystal panel 30 having a display surface 30A, a back surface 30B opposite to the display surface 30A, and an end surface 30C extending between the display surface 30A and the back surface 30B, and a back surface 30B. A support surface 41 that supports the liquid crystal panel 30, a recess 42 provided in a part of the support surface 41 corresponding to the liquid crystal panel 30, and a heat radiation portion 43 provided on the opposite side of the support surface 41. Since the holding member and the recess 42 are provided with the heat conductive filler 50 filled so as to contact the back surface 30B of the liquid crystal panel 30, the liquid crystal panel 30 is accurately aligned. , It is possible to suppress the occurrence of distortion of the liquid crystal panel 30 at the time of temperature change. At the same time, the heat generated in the liquid crystal panel 30 by the incidence of light from the light source can be efficiently released from the heat radiating portion 43 to the outside through the heat conductive filler 50. For this reason, it is possible to suppress image quality deterioration due to luminance unevenness while suppressing image quality deterioration such as contrast caused by the temperature rise of the liquid crystal panel 30.

  In particular, the wall portion 46 erected along the outer edge of the support surface 41 is provided, and the end surface 30C of the liquid crystal panel 30 is adhered to the wall surface 46S of the wall portion 46 by the adhesive 51 at four locations. The liquid crystal panel 30 can be arranged more accurately with respect to the member 40. At this time, the back surface is not bonded to the heat radiation portion over the entire surface, and the entire end surface 30C is not bonded to the wall surface 46S, but a part (four locations) of the end surface 30C is bonded. The liquid crystal panel 30 is not subjected to mechanical distortion due to bonding. In addition, the display surface 30A is more particularly adhered to the end surface 30C and the wall surface 46S at two or more locations (four locations) than when the end surface 30C is not adhered to the wall surface 46S at all and only the support surface 41 is adhered. The liquid crystal panel 30 can be held with higher accuracy in the in-plane direction.

  Next, specific characteristics of the reflective liquid crystal display element according to this embodiment are shown as examples.

[Example 1]
First, Example 1 will be described with reference to FIGS. 6 and 7A and 7B. FIG. 6 shows the temperature dependence of the viscosity of the thermally conductive filler filled in the recesses in the reflective liquid crystal display device having the configuration of the present embodiment. Here, two types of silicone grease A and silicone grease B are used as heat conductive fillers, and are illustrated by curves 6A and 6B, respectively. Silicone grease A and silicone grease B contain silicone oils having hardnesses that exhibit different temperature dependencies. In FIG. 6, the horizontal axis indicates the temperature in use environment ° C, and the vertical axis indicates the viscosity Pa · s. As shown in FIG. 6, the silicone grease B had a viscosity of 480 Pa · s or less under the conditions of −10 ° C., 25 ° C. and 70 ° C. One silicone grease A had a viscosity in the range of 100 to 480 Pa · s in an environment of 25 ° C. and 70 ° C., but showed a high viscosity of 1000 Pa · s at −10 ° C.

  7A and 7B are diagrams schematically showing the luminance distribution on the display surface of the liquid crystal panel. The liquid crystal panel was bonded to the wall portion of the holding member using an adhesive having a Shore hardness of 30. FIG. 7A shows the luminance distribution in an environment of −10 ° C. when silicone grease A is used. In this case, the luminance gradually decreased and became darker toward the region near the center than the luminance in the peripheral portion. Specifically, when the luminance of the peripheral portion is 100%, 97% in the region indicated by the curve 7A, 94% in the region indicated by the inner curve 7B, and in the region indicated by the inner curve 7C. Shows 90% luminance. On the other hand, FIG. 7B shows a luminance distribution in an environment of −10 ° C. when silicone grease B is used. In this case, almost uniform luminance was obtained, and luminance unevenness was not detected. Although not shown, even with silicone grease A, brightness unevenness was not detected in an environment of 25 ° C. and 70 ° C. However, the luminance unevenness shown in FIG. 7 (A) is at a level that does not cause a problem in actual use, and the conventional surface opposite to the display surface is used with an adhesive tape or a paste-like adhesive. This is different from the degree of luminance unevenness that occurs in a structure that adheres to the heat radiating part and causes a problem in actual use.

  From the above results, according to this example, the thermally conductive filler can secure a viscosity in the range of 100 Pa · s to 1000 Pa · s in an environment of −10 ° C. to 70 ° C. It has been found that the use of the conductive filler can suppress the occurrence of luminance unevenness which causes a problem in actual use. In particular, when a thermally conductive filler exhibiting a viscosity in the range of 100 Pa · s to 480 Pa · s is used, a substantially uniform luminance can be obtained over the entire display surface.

[Example 2]
Next, Example 2 will be described with reference to FIG. FIG. 8 shows the distribution of black illuminance on the display surface of the liquid crystal panel. Coordinate points 301 to 304 in FIG. 8 correspond to the four corner points 301 to 304 of the display surface 30A shown in FIG. That is, the XY plane formed by the X axis and the Y axis in FIG. 8 corresponds to the display surface. The Z axis in FIG. 8 indicates the relative black illuminance. 8A, 8B, and 8C are different from each other in Shore hardness of the adhesive (adhesive 51 in FIG. 5) that bonds the liquid crystal panel and the wall portion of the holding member. 8A shows a case where the Shore hardness is 30, FIG. 8B shows a case where the Shore hardness is 65, and FIG. 8C shows a case where the Shore hardness is 90. As is apparent from FIGS. 8A, 8B, and 8C, as the Shore hardness of the adhesive increases, a noticeable bias occurs in the distribution of relative black illuminance. In particular, when the relative black illuminance tends to increase at the coordinate points 30A1 to 30A4 at the four corners, and the Shore hardness shown in FIG. 8C is 90, the black illuminance whose maximum peak is about 10 times that of other regions. It became. Such a distribution of relative black illuminance cannot absorb displacement due to thermal expansion (thermal contraction) at the time of temperature change by bonding the liquid crystal panel to the wall portion of the holding member with a relatively hard adhesive. This is nothing but an indication that mechanical distortion has occurred in the liquid crystal panel. When the Shore hardness was 65 or less, the displacement due to thermal expansion (thermal contraction) could be absorbed, and the uneven distribution of black illuminance could be suppressed.

  From the above results, it was confirmed that by using an adhesive having a Shore hardness in the range of 30 to 65, a good distribution of black illuminance with little bias can be obtained.

  The present invention has been described with reference to the embodiment and some examples. However, the present invention is not limited to this, and various modifications can be made. For example, in the present embodiment and the modification, an example of a three-plate type liquid crystal projector has been described, but the present invention is widely applicable to other types of projectors such as a single plate type.

  Further, in the present embodiment and examples, the case where the end face of the liquid crystal panel is bonded to at least the wall portion of the holding member with an adhesive at four positions has been described, but the present invention is not limited to this, and the liquid crystal panel It can also be made to adhere only to the supporting surface of the holding member with an adhesive at locations where the end surface of the substrate is two or more. Specifically, in FIG. 5, the end surface 30C is not bonded to the wall portion 46 (wall surface 46S), and is bonded to the support surface 41 with an adhesive at two or more locations of the support portions 41A to 41D. May be. However, also in this case, it is preferable to bond the end face 30C to all of the support portions 41A to 41D.

1 is a configuration diagram illustrating an overall configuration of a reflective liquid crystal projector according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view illustrating a configuration of a reflective liquid crystal display element in the reflective liquid crystal projector illustrated in FIG. 1. FIG. 3 is a perspective view illustrating a perspective configuration of a holding member in the reflective liquid crystal display element illustrated in FIG. 2. It is a perspective view showing the perspective structure of the holding member as a modification in the reflective liquid crystal display element shown in FIG. FIG. 3 is a plan view illustrating a planar configuration of the reflective liquid crystal display element illustrated in FIG. 2. It is a characteristic view showing the temperature dependence of the viscosity in the heat conductive filler with which the reflection type liquid crystal display element shown in FIG. 2 was filled. It is explanatory drawing showing the luminance distribution in the display surface of the reflection type liquid crystal display element shown in FIG. It is a characteristic view showing the distribution of black illuminance on the display surface of the reflective liquid crystal display element shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Light source, 12 ... PS converter, 13, 17 ... Dichroic mirror, 14, 15, 16 ... Total reflection mirror, 18, 19, 20 ... Polarizing beam splitter, 21R, 21G, 21B ... Reflection type liquid crystal display element, 22 ... Cross prism, 23 ... projection lens, 30 ... liquid crystal panel, 30A ... display surface, 30B ... back surface, 30C ... end face, 31 ... transparent electrode substrate, 32 ... pixel electrode substrate, 41 ... support surface, 42 ... recess, 43 ... heat dissipation Part, 44 ... radiation fin, 45, 45A ... accommodating part, 46 ... wall part, 47S ... wall surface, 50 ... heat conductive filler, 60 ... pedestal.

Claims (12)

A display surface that displays an image by modulating and reflecting light from a light source in units of pixels based on an image signal, a back surface opposite to the display surface, and extending between the display surface and the back surface. A reflective liquid crystal panel having an existing end face;
A support surface that is in contact with the back surface of the liquid crystal panel and supports the liquid crystal panel, a concave portion provided in a part of the support surface corresponding to the liquid crystal panel, and a side opposite to the support surface. A holding member having a heat radiating portion;
The recess is filled so as to be in contact with the back surface of the liquid crystal panel , and the viscosity is in the range of 100 to 1000 [Pa · s] in the temperature range of minus 10 ° C. to plus 70 ° C. reflection type liquid crystal display device that includes a thermally conductive filler having a. The container further includes an accommodating portion for accommodating an excess portion of the thermally conductive filler filled in the recess .
Reflection type liquid crystal display device according to 請 Motomeko 1. Said end face of said liquid crystal panel, in two or more places, that have been bonded to the support surface of the holding member by an adhesive
Reflection type liquid crystal display device according to 請 Motomeko 1. The holding member further includes a wall portion erected along an outer edge of the support surface,
It said end face of said liquid crystal panel, in two or more locations, that is adhered to at least the wall portion by an adhesive
Reflection type liquid crystal display device according to 請 Motomeko 1. The two or more portions are you equidistant from the center of the display surface
Reflection type liquid crystal display device according to 請 Motomeko 3. The two or more portions are you equidistant from the center of the display surface
Reflection type liquid crystal display device according to 請 Motomeko 4. Wherein the thermally conductive filler is Ru Ah with silicone grease
Reflection type liquid crystal display device according to 請 Motomeko 1. The viscosity of the thermally conductive filler is in the temperature range of minus 10 ° C to plus 70 ° C.
In the range of 100 to 480 [Pa · s].
The reflective liquid crystal display element according to claim 1. Shore hardness of the adhesive, Ru near the range of 20 or more 65 or less
Reflection type liquid crystal display device according to 請 Motomeko 3. Shore hardness of the adhesive, Ru near the range of 20 or more 65 or less
Reflection type liquid crystal display device according to 請 Motomeko 4. A light source;
A reflective liquid crystal display element that forms and displays an image according to an image signal using light from the light source;
Projecting means for projecting an image formed by the reflective liquid crystal display element on a screen,
The reflective liquid crystal display element is
A display surface that displays an image by modulating and reflecting light from the light source in units of pixels based on the image signal, a back surface opposite to the display surface, and between the display surface and the back surface A reflective liquid crystal panel having an end surface extending to
A support surface that is in contact with the back surface of the liquid crystal panel and supports the liquid crystal panel, a concave portion provided in a part of the support surface corresponding to the liquid crystal panel, and a side opposite to the support surface. A holding member having a heat radiating portion;
The recess is filled so as to be in contact with the back surface of the liquid crystal panel , and the viscosity is in the range of 100 to 1000 [Pa · s] in the temperature range of minus 10 ° C. to plus 70 ° C. images projection apparatus and a thermally conductive filler having a. further,
Color separation means for separating light from the light source into a plurality of color lights;
A beam splitter that is provided for each color light separated by the color separation means, reflects incident color light toward the liquid crystal panel, and transmits reflected light from the liquid crystal panel;
And color synthesis means for synthesizing each color light transmitted through each beam splitter,
The liquid crystal panel, that is attached to the beam splitter via a pedestal
The image projection apparatus according to 請 Motomeko 11.

Images