JP2010128293A - Liquid crystal element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal element capable of preventing warpage of a liquid crystal cell which has a polymer scattering type liquid crystal held between two flexible substrates and to which a reflective film and a UV cutting film are stuck, by a simple method. <P>SOLUTION: The liquid crystal element 100 includes the liquid crystal cell 10 which has the polymer scattering type liquid crystal 5 held between the flexible substrates 3 and 6, the UV cutting film 1 stuck onto a viewer side of the liquid crystal cell 10 and the reflection plate 8 stuck onto the side opposite to the viewer side of the liquid crystal cell. The substrates 3, 6 and the reflection plate 8 have nearly equal coefficients of linear expansion, and a film 9 made of the same material as the UV cutting film is stuck onto the side opposite to the viewer side of the reflection plate 8. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid crystal element having a liquid crystal cell in which a polymer scattering type liquid crystal is sandwiched between two flexible substrates.

  In general, a polymer scattering type liquid crystal cell has a structure in which a polymer scattering liquid crystal whose scattering mode and transmission mode can be electrically controlled is sandwiched between two transparent substrates and no polarizing plate is provided.

  However, since such a liquid crystal cell is not provided with a polarizing plate, its characteristics are easily changed by ultraviolet rays. For this reason, an ultraviolet cut film is often provided on the viewing side. For example, in claim 1 of the following Patent Document 1, “... in the polymer scattering type liquid crystal element, on the outer surface side of the upper substrate, a window frame plate, and a composite surface plate having an ultraviolet ray cutting action and an antiglare action are provided. Laminate in order ... ". One feature of Patent Document 1 is that a composite substrate having two functions of ultraviolet cut and anti-glare is used, whereas an ultraviolet cut plate has been used alone until then.

In addition to these circumstances, the present inventor has requested a reduction in thickness and weight, so that the present inventor uses a flexible polycarbonate (hereinafter referred to as PC) substrate as a transparent substrate in place of a glass substrate, and the liquid crystal cell has an anti-reflection effect. A transflective plate made of a reflective polarizing plate {for example, DBEF (registered trademark) manufactured by Sumitomo 3M Co., Ltd.} was attached to the viewing side as a reflective plate. Further, an ultraviolet cut film made of triacetyl cellulose (hereinafter referred to as TAC) was attached to the viewing side.
JP-A-5-241134 (Claim 1, FIG. 1)

  There was no problem of deformation or the like in the normal temperature range in the state where the above-mentioned reflector was pasted on this liquid crystal cell. However, when a UV cut film made of TAC was applied, the liquid crystal cell warped at a high temperature. This will be described with reference to FIG. FIG. 8 is a perspective view showing a warped state of a conventional liquid crystal cell. The liquid crystal cell includes an upper substrate 82 and a lower substrate 83, and an ultraviolet cut film 81 is pasted on the viewing side, and a reflector 84 is pasted on the non-viewing side. As described above, this liquid crystal cell was warped so that the anti-viewing side became convex at a high temperature.

  The present invention has been made in view of the above-mentioned problems of the prior art, and a liquid crystal cell in which a polymer scattering liquid crystal is sandwiched between two flexible substrates and a reflector and an ultraviolet cut film are attached. It is an object of the present invention to provide a liquid crystal element capable of preventing the warpage by a simple method.

  The present invention relates to a liquid crystal cell in which a polymer scattering type liquid crystal is sandwiched between flexible substrates, an ultraviolet cut film attached to the viewing side of the liquid crystal cell, and an anti-viewing side of the liquid crystal cell. In the liquid crystal element including the reflective plate, the linear expansion coefficient of the substrate of the liquid crystal cell and the reflective plate are substantially equal, and a film made of the same material as the ultraviolet cut film is attached to the anti-viewing side of the reflective plate. And

According to the present invention, since the linear expansion coefficient is substantially equal between the substrate and the reflecting plate, no warpage occurs even if the ambient temperature changes in a state where only the liquid crystal cell and the reflecting plate are bonded. When an ultraviolet cut film is affixed thereto, warpage occurs according to changes in the ambient temperature based on differences in the linear expansion coefficients of the ultraviolet cut film, the liquid crystal cell, and the reflector. Therefore, when a film made of the same material as the UV-cut film is attached to the anti-viewing side of the reflector, the warp based on the difference in linear expansion coefficient between the film, the liquid crystal cell and the reflector is in the opposite direction to the aforementioned warp. Since it is going to occur, the warping force between the ultraviolet ray cut side and the film side is offset, so that the warpage of the liquid crystal cell is suppressed.

  In this case, the reflection plate may be a transflective plate.

  The transflective plate may be a reflective polarizing plate that reflects one linearly polarized light out of two orthogonal linearly polarized light and transmits the other linearly polarized light.

  It is preferable that the film affixed on the anti-viewing side of the ultraviolet cut film and the reflector is made of triacetyl cellulose.

  A lower layer member arranged without being adhered to the film may be provided on the non-viewing side of the film.

  The lower layer member may be a display unit that displays character information or the like.

  The lower layer member may be a switch sheet module.

  Further, the lower layer member may be a back lighting device.

  ADVANTAGE OF THE INVENTION According to this invention, the liquid crystal element which made it difficult to generate | occur | produce the curvature of a liquid crystal cell by the simple method of sticking the same film as an ultraviolet-ray cut film on the anti-viewing side of a reflecting plate can be provided.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or corresponding elements will be denoted by the same reference numerals, and redundant description will be omitted (the same applies hereinafter).
(First embodiment)

  FIG. 1 is a plan view showing a liquid crystal cell 10 and a member attached to the liquid crystal cell 10 in the liquid crystal element 100 according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view of the liquid crystal element 100 shown in FIG.

  The members attached to the liquid crystal cell 10 and the liquid crystal cell 10 in FIG. 1 will be described. The lower substrate 6 of the liquid crystal cell 10 is seen to protrude from the ultraviolet cut film 1. An electrode (not shown) for connection with an external circuit is formed on the protruding portion of the lower substrate 6. The upper substrate of the liquid crystal cell 10 and the reflector and the anti-viewing film attached to the anti-viewing side of the lower substrate 6 are not shown because they have the same planar size as the ultraviolet cut film 1. .

A laminated structure of the liquid crystal cell 10 and a member attached to the liquid crystal cell 10 in FIG. 2 will be described. A reflective plate 8, a liquid crystal cell 10, and an ultraviolet cut film 1 are laminated on the film 9 on the counter-viewing side. In the liquid crystal cell 10, the upper substrate 3 and the lower substrate 6 face each other, and the polymer scattering liquid crystal layer 5 is formed in the space formed by the seal 4 and the upper and lower substrates 3 and 6 at the periphery of the upper substrate 3. Is pinched. The ultraviolet cut film 1 and the upper substrate 3 are attached with an adhesive 2. Similarly, the lower substrate 6 and the reflecting plate 8 are attached with an adhesive 7, and the reflecting plate 8 and the anti-viewing side film 9 are attached with an adhesive 11. Note that the transparent electrodes formed on the opposing surfaces of the upper and lower substrates 3 and 6 of the liquid crystal cell 10 are not shown.

  Next, each member will be described. The ultraviolet cut film 1 and the film 9 on the non-viewing side are made of TAC and have a thickness of 40 μm, for example. The upper and lower substrates 3 and 6 of the liquid crystal cell 10 have PC as a base material and are coated with a thin resin on the surface, and have a thickness of, for example, 100 μm. The polymer liquid crystal layer 5 is a layer in which liquid crystal molecules are accumulated in voids in the polymer network, and has a thickness of about 10 μm, for example. The transparent electrode (not shown) is made of ITO, and is patterned with a thickness of, for example, 0.03 μm. The reflector 8 uses, for example, DBEF (registered trademark) manufactured by Sumitomo 3M, and has a thickness of, for example, 240 μm.

  The linear expansion coefficient of PC is about 7 × 10E-5 (/ ° C.). Regarding the linear expansion coefficients of TAC and DBEF, a sample of several centimeters (the sample outer shape of each member is equal) was placed on a heat stage, and the deformation was compared under a microscope while heating. As a result, the deformation amount of each sample was as shown in Table 1.

(Table 1)

    Thus, although the linear expansion coefficients of the upper and lower substrates 3 and 6 and the reflector 8 are substantially equal, the ultraviolet cut film 1 and the film 9 on the non-viewing side have a lower linear expansion coefficient than the upper and lower substrates 3 and 6. Yes.

Since the linear expansion coefficients of the substrates 3 and 6 and the reflecting plate 8 are substantially equal, the configuration in which only the reflecting plate 8 is bonded to the liquid crystal cell 10 does not warp even when the ambient temperature changes. However, when the ultraviolet cut film 1 is attached to this configuration, the balance of the linear expansion coefficient is lost, and warping occurs according to changes in the ambient temperature. In the liquid crystal element 100 according to the present embodiment, since a film 9 made of the same material as the ultraviolet cut film 1 is further attached to the anti-viewing side of the reflector, a force acting opposite to the above-described warp works. Thus, the balance of the linear expansion coefficient is maintained, and the warpage of the liquid crystal cell 10 is suppressed.
(Second Embodiment)

    FIG. 3 is a cross-sectional view showing a liquid crystal element 41 according to the second embodiment of the present invention, and FIG. 4 is a perspective view of the liquid crystal element 41 shown in FIG.

  First, a state in which the display unit 30 is arranged under the liquid crystal cell 10 in FIG. 3 will be described. The liquid crystal cell 10, the ultraviolet cut film 1, the reflector 8, the film 9 on the non-viewing side, etc. are the same as those in FIG. A display unit 30 is disposed under the film 9 on the side opposite to the viewing side through an air layer. Since the air layer only needs to be able to slide between the film 9 and the display unit 30, the thickness is arbitrary, and the film 9 and the display unit 30 may be in contact with each other. The display unit 30 has a TFT liquid crystal cell 31 laminated on an illumination device 32. The reflecting plate 8 is a reflective polarizing plate that reflects one of the two orthogonally polarized light beams and transmits the other linearly polarized light, so that the transmission axis of the reflecting plate 8 and the viewing side of the TFT liquid crystal cell 31 are on the viewing side. The transmission axis of a polarizing plate (not shown) is made parallel.

Next, the operation state of the liquid crystal element 41 will be described with reference to FIG. 4A and 4B show a standby mode and an image display mode of the liquid crystal element 41, respectively. In the standby mode of FIG. 4A, the surface of the liquid crystal element 41 has a time display unit 42, and the background region is clouded. In this cloudy region, the liquid crystal layer 5 of the liquid crystal cell 10 is off (scattering state). In the segment indicating the time in the time display unit 42, the liquid crystal layer 5 of the liquid crystal cell 10 is turned on (transparent state), and the surface of the reflector 8 is shown. At this time, the display unit 30 is stopped. In the image display mode of FIG. 4B, the illumination device 32 is turned on and an image is displayed on the TFT liquid crystal cell 31. Accordingly, the liquid crystal layer 5 is turned on (transparent state) in the screen region 43 of the liquid crystal cell 10. As described above, since the transmission axis of the reflection plate 8 (reflection type polarizing plate) and the polarizing plate on the upper surface of the TFT liquid crystal cell 31 are parallel, the image displayed on the TFT liquid crystal cell 31 can be visually recognized. That is, the liquid crystal element 41 is in a low power consumption state in the standby mode, and displays a fine image in the image display mode.

  In such a liquid crystal element according to the first and second embodiments, the film 9 on the anti-viewing side is thin like the ultraviolet cut film 1, and therefore, an increase in the thickness of the entire liquid crystal element can be reduced. Further, since the film 9 is optically isotropic, the display image of the TFT liquid crystal cell 31 is hardly deteriorated.

  In addition, since there is an air layer between the film 9 and the TFT liquid crystal cell 31, no strain or stress is generated between the TFT liquid crystal cell 31 and the film 9 even if the expansion rates of the film 9 and the TFT liquid crystal cell 31 are different. . The same effect can be obtained by interposing a weak adhesive layer such as an elastomer in place of the air layer.

Since the reflection plate 8 has substantially the same expansion coefficient as the substrates 3 and 6, the thickness can be ignored as far as warping is concerned, and mechanism design and material procurement are facilitated. Although the display unit 30 uses the TFT liquid crystal cell 31, it may be an organic LED cell or another light emitting display. In this case, the illumination device 32 becomes unnecessary.
(Third embodiment)

  Next, the configuration of the liquid crystal element according to the third embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a cross-sectional view showing a liquid crystal element 61 according to the third embodiment, and FIG. 6 is a perspective view of the liquid crystal element shown in FIG.

  In FIG. 5, a laminated structure of a liquid crystal cell and a member attached to the liquid crystal cell will be described. In contrast to FIG. 3, regarding the liquid crystal cell 10 and the member attached to the liquid crystal cell 10, the reflective plate 8 that is a reflective polarizing plate is replaced with a reflective plate 54 that is a semi-transmissive reflective plate, As for the lower layer member, the display unit 30 is replaced with the switch sheet module 50. In the switch sheet module 50, a light guide sheet 51 is laminated on a switch sheet 52, and a light source 53 is attached to a side surface of the light guide sheet 51. The electrode pattern of the liquid crystal cell 10 (not shown) is different from the first and second embodiments.

  Next, each member will be described. The reflection plate 54 is a half mirror (semi-transmissive reflection plate) in which a metal thin film is formed on a substrate made of PC, and has a thickness of, for example, 100 μm and is flexible. The light guide sheet 51 is made of silicone, has a thickness of, for example, 200 μm, and emits light incident from the light source 53 to the liquid crystal cell 10 side by a prism formed on the viewing side. The switch sheet 52 includes a plurality of pressure sensitive switches (not shown) arranged on a substrate. The pressure-sensitive switch is composed of a contact formed on the substrate and a dome-shaped electrode provided thereon, and when a pressure is applied, the dome-shaped electrode is deformed and connected to the contact (ON).

Next, the operation state of the liquid crystal element 61 will be described with reference to FIG. 6A and 6B show the number display mode and the picture display mode of the liquid crystal element 61. FIG. In the number display mode of FIG. 6A, a number 62 is displayed on the surface of the liquid crystal display 61. As in the second embodiment, the numeral 62 indicates a mirror surface on a white background. A pressure-sensitive switch is arranged below each number 62. When the number 62 is pressed, the liquid crystal cell 10, the reflection plate 54, and the light guide sheet 51 are deformed, and the corresponding pressure-sensitive switch is turned on. In the picture display mode of FIG. 6B, the picture 63 is displayed at the position where the number 62 is displayed in the number mode of FIG. 6A, and the corresponding pressure-sensitive switch is turned on when each picture 63 is pressed. . That is, this liquid crystal element has a programmable key input function, and the function of each pressure-sensitive switch is different between the number display mode and the picture display mode.

  In the liquid crystal element according to the third embodiment, the effects of the film 9 and the air layer on the anti-viewing side are the same as those of the second embodiment. In the present embodiment, a highly flexible PC board is used as the reflecting plate 54.

Since each pressure sensitive switch of the switch sheet 52 conducts with a deformation of about 100 μm, the touch becomes hard, but DBEF may be used as the reflector as in the first embodiment. As the substrate material of the reflector, the same PC as the substrate material of the liquid crystal cell has a common coefficient of thermal expansion, but other than PC, materials having a similar coefficient of thermal expansion include polyarylate, amorphous polyolefin, cyclohexane. An olefin polymer or the like can be used. Furthermore, although the light guide sheet 51 and the light source 53 are used as the illumination device of the liquid crystal cell, a flexible EL (electroluminescence) sheet may be used. The switch sheet 52 can be replaced with a pressure-sensitive resistance sheet whose resistance value changes with pressure.
(Fourth embodiment)

  Next, the configuration of the liquid crystal element according to the fourth embodiment of the present invention will be described with reference to FIG. FIG. 7 is a cross-sectional view showing a liquid crystal element 102 according to the fourth embodiment.

  In FIG. 7, a laminated structure of members will be described. The liquid crystal cell 10 and the member attached to the liquid crystal cell 10 are the same as those in the first embodiment shown in FIG. The electrode pattern of the liquid crystal cell 10 is different from that of the first embodiment so that various information can be displayed. A back lighting device 71 is disposed under the film 9 on the non-viewing side via an air layer. This liquid crystal element performs reflective display when the surroundings are bright, and turns on the backlighting device 71 to perform transmissive display when the surroundings become dark.

  As mentioned above, although this invention was concretely demonstrated based on embodiment, this invention is not limited to the said embodiment. For example, in the above embodiment, a reflection plate having both a transmission function and a reflection function is used as the reflection plate, but a reflection plate having no transmission function may be used. In this case, if use in a dark place is assumed, a front light may be provided.

  In the first and fourth embodiments, the linear expansion coefficients of the liquid crystal cell 10 and the reflecting plate 8 are substantially equal. In the third embodiment, the liquid crystal cell 10 and the reflecting plate 54 are made of the same material, and the linear expansion coefficients are equal. Was. However, since it is sufficient that the linear expansion coefficients of the liquid crystal cell and the reflecting plate are substantially equal, a modified acrylic resin, polymethacrylic resin, polyethersulfone resin can be used as a flexible optical transparent substrate in addition to PC. A substrate material can be selected from polyethylene terephthalate resin, norboltene resin, and the like. Furthermore, one liquid crystal cell may be divided into a plurality of regions, and a display unit, a switch sheet module, a back device, and other lower layer members may be disposed under each region.

It is a top view which shows the liquid crystal cell and the member affixed on the liquid crystal cell in the liquid crystal element which concerns on 1st Embodiment of this invention. It is sectional drawing of the liquid crystal element shown in FIG. It is sectional drawing which shows the liquid crystal element which concerns on 2nd Embodiment of this invention. FIG. 4 is a perspective view of the liquid crystal element shown in FIG. 3. It is sectional drawing which shows the liquid crystal element which concerns on 3rd Embodiment of this invention. FIG. 6 is a perspective view of the liquid crystal element shown in FIG. 5. It is sectional drawing which shows the liquid crystal element which concerns on 4th Embodiment of this invention. It is a perspective view which shows the state which the conventional liquid crystal cell warped.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,81 ... Ultraviolet cut film, 2, 7, 11 ... Adhesive material 3, 6, 82, 83 ... Substrate, 8, 54, 84 ... Reflector, 9 ... Film on the non-viewing side, 10 ... Liquid crystal cell, 30 DESCRIPTION OF SYMBOLS ... Display unit, 31 ... TFT liquid crystal cell, 71 ... Backlighting device, 100, 41, 61, 102 ... Liquid crystal element, 42 ... Time display part, 43 ... Screen area, 50 ... Switch sheet module, 51 ... Light guide sheet, 52 ... Switch sheet, 53 ... Light source, 62 ... Number, 63 ... Picture.

Claims (8)

A liquid crystal cell in which a polymer scattering type liquid crystal is sandwiched between flexible substrates, an ultraviolet cut film attached to the viewing side of the liquid crystal cell, and a reflector attached to the non-viewing side of the liquid crystal cell In a liquid crystal element comprising:
The linear expansion coefficient of the substrate and the reflector is approximately equal,
A liquid crystal element, wherein a film made of the same material as the ultraviolet cut film is affixed to the anti-viewing side of the reflector.   The liquid crystal element according to claim 1, wherein the reflecting plate is a transflective plate.   3. The liquid crystal device according to claim 2, wherein the transflective plate is a reflective polarizing plate that reflects one linearly polarized light and transmits the other linearly polarized light out of two orthogonal linearly polarized light. 4. .   4. The liquid crystal device according to claim 1, wherein the ultraviolet cut film and the film are made of triacetyl cellulose. 5.   The liquid crystal element according to any one of claims 1 to 4, further comprising a lower layer member arranged on the side opposite to the visual recognition side of the film without being bonded to the film.   The liquid crystal element according to claim 5, wherein the lower layer member is a display unit that displays character information and the like.   The liquid crystal element according to claim 5, wherein the lower layer member is a switch sheet module. The liquid crystal element according to claim 5, wherein the lower layer member is a backlight device.