JP4760155B2 - Liquid crystal display element and liquid crystal projector - Google Patents

Description

  The present invention relates to a liquid crystal display element in which two substrates are bonded through a sealing material, and liquid crystal is sealed in a display region surrounded by the sealing material, and a liquid crystal projector using the liquid crystal display element, in particular. The present invention relates to a liquid crystal display element and a liquid crystal projector that can suppress a gap variation between two substrates due to heat.

  When a liquid crystal element is used as a display element, reversible expansion and contraction occurs due to a temperature expansion component of the liquid crystal. For this reason, there is a concern that the display quality is lowered, and Patent Document 1 discloses a method of minimizing the influence of external pressure change by having a wall spacer structure. Patent Document 2 discloses an example in which a tube-shaped gap change absorbing material is provided outside the seal. Furthermore, Patent Document 3 describes a configuration in which a gap variation is controlled using an adhesive spacer.

JP 2001-343654 A JP-A-10-301123 JP-A-2-87120

  However, the structure having the wall spacer described in Patent Document 1 is not suitable for miniaturization because a double spacer wall region is required. Further, in the configuration in which the tube-shaped gap change absorbing material described in Patent Document 2 is provided, only the change in the vicinity of the seal is controlled, and is not effective for suppressing the entire panel. Further, in the configuration in which the gap variation is controlled using the adhesive spacer described in Patent Document 3, since the spacer is installed in the effective pixel, when used as a projector liquid crystal display element, the image quality is remarkably reduced. become. Particularly in recent years, since the thickness of the substrate has been reduced, the variation in the gap between the substrates has become noticeable due to the pressure due to the thermal expansion of the liquid crystal.

  The present invention has been made to solve such problems. That is, the present invention relates to a liquid crystal display element in which a first substrate and a second substrate are bonded together via a sealing material, and liquid crystal is sealed in a display region surrounded by the sealing material. The liquid crystal display element is provided with a buffer region which is in communication with the region and into which liquid crystal enters from the display region by thermal expansion.

  In the present invention, when the temperature of the liquid crystal display element rises, the volume of the buffer region increases due to the heat, and a part of the liquid crystal in the display region enters the buffer region in proportion to the increase in the volume. Become. Thereby, even if the liquid crystal in the display area is thermally expanded, the pressure due to the expansion can be released to the buffer area side, and an increase in the gap between the substrates in the display area can be prevented.

  In addition, since the buffer region is provided with a thermal expansion material made of a material having a thermal expansion coefficient larger than that of the liquid crystal, a thermal expansion material that increases the volume into which the liquid crystal enters by thermal expansion is provided. The volume of the buffer region is increased before the gap between the substrates is expanded by the pressure, and the pressure of the liquid crystal can be released to the buffer region side.

  The buffer area only needs to be arranged at a position that does not affect the image display in the display area, but is provided adjacent to the display area between the first base and the second base. Desirably, if it is provided on the liquid crystal inlet side, it is advantageous in manufacturing.

  Further, the present invention is a liquid crystal projector using such a liquid crystal display element. Further, in the structure in which the liquid crystal display element is provided corresponding to a plurality of surfaces of the block-shaped dichroic mirror, each buffer of each liquid crystal display element is provided. The region is disposed at a position where it does not interfere with the adjacent liquid crystal display element.

  A liquid crystal projector in which liquid crystal display elements are respectively provided corresponding to a plurality of surfaces of a dichroic mirror is mainly for color image display, and liquid crystal display elements corresponding to each color of R (red), G (green), and B (blue) Is used. By arranging the buffer region provided in the liquid crystal display element corresponding to each color at a position not buffered with the adjacent liquid crystal display device, the buffer region can be effectively used without affecting the optical path of each color.

  Therefore, according to the present invention, it is possible to suppress an increase in the gap between the substrates due to the temperature rise of the liquid crystal display element, and it is possible to maintain high image quality. In particular, when the liquid crystal display element of the present invention is applied to a liquid crystal projector, even if the temperature rises due to the influence of a heat source such as a lamp, an increase in the gap between the substrates does not occur, image quality deterioration can be suppressed, and high quality It becomes possible to provide a liquid crystal projector.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view illustrating the basic structure of the liquid crystal display element according to this embodiment. The liquid crystal display element 1 according to the present embodiment is characterized in that an increase in the inter-substrate gap in the display region can be suppressed by expansion due to heating. In particular, in the liquid crystal display element 1 used in an SXRD (Silicon Crystal Reflective Display) panel using a semiconductor substrate such as silicon as the driving substrate 20, the spacer S is not scattered in the display region. Spacers S are arranged to control the cell thickness. For this reason, the liquid crystal L expands due to the temperature rise, and the gap in the center in the plane farthest from the sealing material 30 tends to be widened. In the present embodiment, in order to suppress this, the buffer area provided outside the display area (effective area) can absorb the expansion in the display area.

  First, the basic structure of the liquid crystal display element 1 will be described with reference to FIG. That is, the liquid crystal display element 1 includes a reflective liquid crystal display element, and a glass substrate (first base) 10 and a drive substrate (second base) 20 are bonded to each other with a predetermined gap, and the gap is within the gap. The liquid crystal L is sealed in and driven.

  As a configuration of the liquid crystal display element 1, a driving substrate 20 made of a single crystal semiconductor substrate such as silicon provided with a light reflecting electrode 21 having a pixel structure, and a glass substrate 10 which is a transparent substrate with a transparent electrode 11 facing the driving substrate 20. The liquid crystal L is sealed between them. The liquid crystal L such as vertical alignment is aligned by alignment films 12 and 22 formed on the opposing surfaces of the glass substrate 10 and the driving substrate 20.

  In the reflection type liquid crystal display element, a driving circuit including a transistor and a capacitor made of CMOS (Complementary Metal Oxide Semiconductor) or n-channel MOS (Metal Oxide Semiconductor) is formed on a single crystal silicon substrate as a driving substrate 20, and an Al is formed thereon. The light reflecting electrode 21 is formed of a metal film such as (aluminum) or Ag (silver) to form a pixel structure. The light reflecting electrode 21 serves as both a light reflecting film and a voltage electrode applied to the liquid crystal.

  A dielectric multilayer film may be formed on the metal film in order to improve the reflectance or as a protective film for the metal surface.

  The two substrates are bonded and fixed by a sealing material 30 mixed with a spacer S for keeping the thickness constant. This spacer S is spherical and is mixed in the sealing material 30 at a ratio of about 0.5 to 5 wt%. In an actual element, the spacers S are scattered in the sealing material 30. That is, when considered as a cross-sectional structure, in most regions, the boundary between the inside and outside of the element is the sealing material 30 itself.

  In such a structure of the liquid crystal display element 1, if the liquid crystal seal structure is uniform, the cell thickness may become non-uniform due to a change in thermal expansion of the liquid crystal material due to a change in environmental temperature. Therefore, it is possible to form a cell that can sufficiently cope with a change in the temperature environment of the cell by forming a buffer structure corresponding to the change in the temperature environment of the cell.

  2A and 2B are schematic views for explaining the liquid crystal display element according to the present embodiment, in which FIG. 2A is a plan view and FIG. 2B is a side view. In the liquid crystal display element 1, a glass substrate 10 that is a first base and a drive substrate 20 that is a second base are bonded to each other through a sealing material 30, and the display is surrounded by the sealing material 30 at the center of the substrate. The liquid crystal L is sealed in the region A1. Further, a buffer region A2 surrounded by the sealing material 30 in a state communicating with the display region A1 is provided.

  The buffer area A2 is partitioned by a sealing material 30 that is partially opened from the display area A1, and is provided at the end of the substrate in this state, and the liquid crystal L communicates with the display area A1 through the opening. It has come in. In addition, it is preferable on manufacture that buffer area | region A2 is provided in the injection port side of the liquid crystal L. FIG.

  In such a buffer area A2, the volume is increased by thermal expansion, and a part of the liquid crystal L in the display area A1 enters the buffer area A2 in proportion to the increase in the volume. Thereby, the pressure of the liquid crystal L due to thermal expansion can be released to the buffer area A2, and the force to widen the inter-substrate gap in the display area A1 can be reduced, and a constant gap in the display area A1 can be maintained. become able to.

  In addition, in the buffer region A2, an expansion material B is provided so that the volume of the buffer region A2 can be efficiently increased by heat. The expansion material B is interposed between the glass substrate 10 and the drive substrate 20, and by using a material having a larger thermal expansion coefficient than the liquid crystal L, the liquid crystal L is thermally expanded to push the gap between the substrates in the display area A1. Before expanding, the volume of the buffer area A2 can be increased, and the pressure by the liquid crystal L can be released to the buffer area A2 side.

As a specific example of the expansion material B, for example, PTFE (polytetrafluoroethylene: thermal expansion coefficient 1 × 10 ⁻³ ) that is a fluororesin or glycerin (thermal expansion coefficient 1 × 10 ⁻⁴ ) that is an oil or fat is used. In addition to these materials, any resin or oil that cannot be mixed with the liquid crystal L and a material having a thermal expansion coefficient larger than that of the liquid crystal L is applicable.

  Next, the manufacturing method of this liquid crystal display element is demonstrated along the schematic diagram of FIGS. First, as shown in FIG. 3, a sealing material 30 is applied to the periphery of the drive substrate 20 on which the drive elements are formed. The sealing material 30 is applied so as to be continuous with the portion to be the buffer region A2 along with the periphery of the portion to be the display region A1. An opening is provided on the buffer area A2 side.

  Next, as shown in FIG. 4, the expansion material B described above is applied to the portion that becomes the buffer region A <b> 2. Here, PTFE is formed in a columnar shape and is applied to have the same thickness as the sealing material 30 or slightly higher. In this state, when the glass substrate 10 is bonded, a space of the display area A1 and the buffer area A2 by the sealing material 30 is formed between the substrates. In the buffer region A2, the expanded material B made of PTFE is provided between the substrates.

  Next, as shown in FIG. 5, the liquid crystal L is injected from the opening of the sealing material 30 on the buffer region A2 side. The liquid crystal L is filled in the display area A1 and also in the buffer area A2 that communicates therewith. Then, as shown in FIG. 6, the opening of the buffer region A <b> 2 is closed with the sealing material 31. Thereby, the liquid crystal display element 1 provided with the buffer region A2 adjacent to the display region A1 is completed.

  As described above, when the buffer region A2 having the expansion material B having a higher thermal expansion coefficient than the liquid crystal L is provided adjacent to the display region A1, the expansion of the display region A1 is sucked by the buffer region A2, and the display region It is possible to effectively suppress the variation in the inter-substrate gap at A1.

  In the above example, the display area A1 is provided in the central portion and the buffer area A2 is provided at the end portion between the same substrates. However, only the display area A1 is provided between the substrates, and the through-hole formed in the drive substrate 20 is provided. A buffer region A2 may be provided on the back surface of the drive substrate 20 through the hole, and the liquid crystal L may be structured to enter the buffer region A2 from the display region A1 through the through hole. In this case, since there is no buffer area A2 on the substrate surface side, the effective area of the display area A1 can be increased.

  In addition, the liquid crystal display element 1 according to the present embodiment is preferably applied to, for example, a projection system (liquid crystal projector) that is severe in temperature conditions in a heating environment. FIG. 7 is a schematic diagram showing an example of a projection system using the liquid crystal display device of the present embodiment. That is, the projection system 100 includes a lamp light source 101, a lens unit 102, a dichroic color separation filter 103, beam splitters 104r, 104g, and 104b, liquid crystal display devices 1r, 1g, and 1b, drive circuits 105r, 105g, and 105b, and a prism (dichroic mirror). ) 106 and the projection lens 107.

  As the liquid crystal display devices 1r, 1g, and 1b, the reflection type liquid crystal display element according to the present embodiment described above is used. Therefore, as the counter electrode formed on the glass substrate 2 shown in FIG. A light reflecting electrode 21 made of aluminum or the like is used as a driving substrate side electrode provided on the driving substrate 20 composed of the above.

  In this system, the light emitted from the lamp light source 101 is sent from the lens unit 102 to the dichroic color separation filter 103, where it is separated in two directions. The light separated in two directions corresponds to three colors R (RED), G (GREEN), and B (BLUE) by total reflection mirrors 108 and 109, beam splitters 104r, 104g, and 104b, dichroic mirror 110, and prism 106. Each of them is sent to a display unit composed of a reflective liquid crystal display device 1r, 1g, 1b.

  For example, the light from the lamp light source 101 is incident on the liquid crystal display device 1r corresponding to R (RED) from the dichroic color separation filter 103 via the total reflection mirror 108 and the beam splitter 104r, and corresponds to G (GREEN). Light from the lamp light source 101 enters the liquid crystal display element 1g from the dichroic color separation filter 103 via the total reflection mirror 108, the dichroic mirror 110, and the beam splitter 104g, and enters the liquid crystal display element 1b corresponding to B (BLUE). The light from the lamp light source 101 enters from the dichroic color separation filter 103 via the total reflection mirror 109 and the beam splitter 104b.

  Each of the liquid crystal display elements 1r, 1g, and 1b is provided via beam splitters 104r, 104g, and 104b in a state corresponding to each of a plurality of surfaces of the prism 106 that is a dichroic mirror. Each of the liquid crystal display elements 1r, 1g, and 1b is driven by the corresponding drive circuit 105r, 105g, and 105b, and the incident light is reflected as an image on the liquid crystal layer, synthesized by the prism 106, and sent to the projection lens 107. It is done. As a result, an image corresponding to three colors R (RED), G (GREEN), and B (BLUE) is projected onto a screen (not shown) and reproduced as a color image.

  In order to apply the liquid crystal display element of this embodiment in such a projection system 100, the buffer regions of the liquid crystal display elements 1r, 1g, and 1b are arranged at positions that do not interfere with the adjacent liquid crystal display elements. Thereby, the buffer system of each liquid crystal display element 1r, 1g, 1b can constitute the projection system 100 without affecting the optical path related to the other liquid crystal display elements.

  In the projection system 100, since the liquid crystal display elements 1r, 1g, and 1b are heated by strong light from the lamp light source 101 in particular, the buffer area A2 provided in each of the liquid crystal display elements 1r, 1g, and 1b as described above. (See FIG. 2) works effectively. That is, the pressure due to the thermal expansion of the liquid crystal can be accurately released to the buffer region A2 side, and even if the liquid crystal display elements 1r, 1g, and 1b are heated, an increase in the inter-substrate gap in the display region A1 can be reliably suppressed. Even when used for a long time, it is possible to maintain high quality image quality.

  Note that the liquid crystal display element of the present embodiment can be applied to a transmission type in addition to the reflection type as described above. In this case, a glass substrate may be used as the pair of substrates, and the electrodes formed on each substrate may be configured with transparent electrodes such as ITO (Indium Tin Oxide). Moreover, although the liquid crystal display element of this embodiment was described about the liquid crystal element used for a projector, this invention is not limited to this, A liquid crystal display, a viewfinder, a mobile phone, a digital still camera, a video camera, etc. The present invention can be widely applied to liquid crystal elements used in LCDs.

It is a schematic cross section explaining the basic structure of the liquid crystal display element concerning this embodiment. It is a schematic diagram explaining the liquid crystal display element which concerns on this embodiment. It is a schematic diagram (the 1) explaining the manufacturing method of the liquid crystal display element which concerns on this embodiment. It is a schematic diagram (the 2) explaining the manufacturing method of the liquid crystal display element which concerns on this embodiment. It is a schematic diagram (the 3) explaining the manufacturing method of the liquid crystal display element which concerns on this embodiment. It is a schematic diagram (the 4) explaining the manufacturing method of the liquid crystal display element which concerns on this embodiment. It is a schematic diagram explaining the liquid crystal projection system which concerns on this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display element, 10 ... Glass substrate (1st base | substrate), 11 ... Transparent electrode, 12 ... Orientation film, 20 ... Drive board | substrate (2nd base | substrate), 21 ... Light reflection electrode, 22 ... Orientation film, 30 ... Sealing material, 100 ... Projection system, A1 ... Display area, A2 ... Buffer area

Claims (6)

In a liquid crystal display element in which a first base and a second base are bonded together via a sealing material, and liquid crystal is sealed in a display region surrounded by the sealing material.
By thermal expansion and through Table view area and the communication are buffer areas provided the LCD from the table display region enters,
The buffer region is provided with an expansion material that increases the volume of liquid crystal that enters due to thermal expansion.
Liquid crystal display element. Rise Zhang material consists of larger material of thermal expansion coefficient than the liquid crystal
The liquid crystal display device according to 請 Motomeko 1. Slow衝領zone is provided adjacent to the table display region between the first substrate and the second substrate
The liquid crystal display device according to 請 Motomeko 1. Slow衝領region is provided on the inlet side of the liquid crystal
The liquid crystal display device according to 請 Motomeko 3. In a liquid crystal projector that magnifies and outputs an image generated by a liquid crystal display element by an optical system,
Liquid crystal display device includes a first substrate and a second substrate bonded via a sealing material, a display area which is formed by sealing a liquid crystal region surrounded by the sealing material,
By thermal expansion and through Table view area and the communication is provided with a buffer region where the liquid crystal from the table display region enters,
The buffer region is provided with an expansion material that increases the volume of liquid crystal that enters due to thermal expansion.
Liquid crystal projector. Liquid crystal display element is provided respectively corresponding to the plurality of surfaces of the dichroic mirror block shape, claim 5 in which each buffer region of each liquid crystal display element is disposed in a position that does not interfere with the liquid crystal display element adjacent the liquid crystal projector according to.

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