JP2012068550A - Reflecting plate and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflecting plate and a liquid crystal display device which can reduce the occurrence rate of color mixture even with a reduced pixel pitch to provide an image of high display quality.SOLUTION: The reflecting plate includes: a base layer 51 on which a plurality of concave portions 51a having a shape corresponding to a part of a surface shape of a sphere are formed; and spherical refracting bodies 53 which have a prescribed refractive index and are fitted into the concave portions 51a so as to partially protrude from the concave portions 51a. Surfaces of portions fitted into the concave portions 51a, of the refracting bodies 53 are coated with a reflective metal 52 which reflects light.

Description

  The present invention relates to a reflector and a liquid crystal display device.

  2. Description of the Related Art In recent years, a reflection type liquid crystal display device that performs display by reflecting external light incident from the front of a liquid crystal panel and once passing through a liquid crystal layer of the liquid crystal panel by a reflecting plate and then emitting the light again from the front of the liquid crystal panel through the liquid crystal layer Has been developed (Patent Document 1). The reflective plate for reflecting the external light has a reflective surface formed with fine irregularities to scatter and reflect the external light, or the reflective surface is flat (specular surface) for specularly reflecting the external light. What is formed is known.

JP-A-10-319386

  By the way, in order to enable color display in the liquid crystal display device, a color filter composed of a plurality of color components is formed. Then, the external light passes through the color filter and is reflected by the reflecting plate, passes through the color filter again, and is visually recognized by the user. However, when external light is scattered and reflected by a fine uneven surface or specularly reflected by a flat surface, the reflected light that is incident and reflected from a direction inclined with respect to the substrate normal is different from the incident direction of light. Reflected in the direction. For this reason, the higher the resolution and the smaller the pixel pitch, the greater the proportion of light that is different between the color component of the color filter that has passed at the time of incidence and the color component of the color filter that has been reflected by the reflector and passed at the time of emission. In such a case, there is a problem that the color of the image displayed on the liquid crystal display device is viewed differently from the color to be originally displayed, and the display quality of the image displayed on the liquid crystal display device is degraded. It was.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a reflector and a liquid crystal display device that can suppress the rate of color mixing even when the pixel pitch is reduced and obtain an image with high display quality.

  In order to achieve the above object, the reflector according to claim 1 has a base layer in which a plurality of recesses having a shape corresponding to a part of the surface shape of a sphere, and a predetermined refractive index. A spherical refractor inserted into the recess so that at least part of the refractor protrudes from the recess, and the refractor reflects light from the surface of the portion inserted into the recess. It is characterized by being covered with metal.

  The invention according to claim 2 is characterized in that, in the reflector according to claim 1, the surface of the refracting body protruding from the recess is exposed from the reflective metal. .

  According to a third aspect of the present invention, in the reflector according to the second aspect, the concave portion is formed in a shape corresponding to a hemisphere.

  The reflector of the invention according to claim 4 is a reflective layer in which at least the surface thereof is made of a reflective metal that reflects light, and a plurality of concave portions having a shape corresponding to a part of the surface shape of the sphere are formed, And a spherical refractor inserted into the recess so as to protrude at least partially from the recess.

  According to a fifth aspect of the present invention, there is provided a liquid crystal display device including a liquid crystal panel in which a liquid crystal layer is formed between a pixel electrode and a counter electrode, and a pair of polarizing plates arranged so as to sandwich the liquid crystal panel. A reflective plate disposed so that one of the pair of polarizing plates is interposed between the display panel and the reflective plate, wherein the reflective plate has a shape corresponding to a part of a surface shape of a sphere. A base layer in which a plurality of recesses are formed, and a spherical refractor that has a predetermined refractive index and is fitted into the recess so that at least a part thereof protrudes from the recess. The surface of the portion inserted into the recess is covered with a reflective metal that reflects light.

  According to a sixth aspect of the present invention, there is provided a liquid crystal display device comprising: a liquid crystal panel in which a liquid crystal layer is formed between a pixel electrode and a counter electrode; and a pair of polarizing plates disposed so as to sandwich the liquid crystal panel. A reflective plate disposed so that one of the pair of polarizing plates is interposed between the display panel and the reflective plate, and the reflective plate is made of a reflective metal whose surface reflects light. And a reflective layer in which a plurality of recesses having a shape corresponding to a part of the surface shape of the sphere are formed, and a sphere having a predetermined refractive index and fitted into the recess so that at least a part protrudes from the recess And a refracting body having a shape.

  According to the present invention, even when the pixel pitch is reduced, the ratio of color mixing can be suppressed, and an image with high display quality can be obtained.

The external force cross-section block diagram of a liquid crystal display device. It is explanatory drawing of a liquid crystal panel, (a) is a top view, (b) is sectional drawing. The equivalent circuit top view of a thin-film transistor array. FIG. 6 is an array diagram of each color component in a color filter. It is explanatory drawing of a reflecting plate, (a) is a schematic explanatory drawing of the reflection characteristic with respect to external light, (b) And (c) is the elements on larger scale of a reflecting plate. Explanatory drawing of the example of an arrangement | sequence of a refractive body. It is explanatory drawing of the manufacturing method of a reflecting plate, (a) is the explanatory diagram of the state which applied the thermosetting resin before hardening on a heat resistant insulating substrate, and an example of a stamper, (b) is thermosetting a stamper. Explanatory drawing of the state pressed against resin, (c) is explanatory drawing of the state which formed the reflection layer into a film. It is explanatory drawing of the manufacturing method of a reflecting plate, (a) is explanatory drawing of the state before inserting the refractive body by which the surface was covered with the metal thin film in the 1st recessed part, (b) is metal in the 1st recessed part. Explanatory drawing of the state after inserting the refractive body by which the surface was covered with the thin film.

Hereinafter, embodiments for implementing a reflector and a liquid crystal display device of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the liquid crystal display device 1 includes a first polarizing plate 2, a second polarizing plate 3, and a liquid crystal disposed between the first polarizing plate 2 and the second polarizing plate 3. The panel 4 and the reflective plate 5 arrange | positioned so that the 2nd polarizing plate 3 may be interposed between the liquid crystal panels 4 are provided. That is, when the liquid crystal display device 1 displays a white image, the external light Li incident on the liquid crystal display device 1 from the side on which the first polarizing plate 2 is disposed, The light passes through the first polarizing plate 2, the liquid crystal panel 4, and the second polarizing plate 3 in order, is reflected by the reflecting plate 5, and the external light Li reflected by the reflecting plate 5 is reflected by the second polarizing plate 3 and the liquid crystal. The liquid crystal display device 1 is configured to pass through the panel 4 and the first polarizing plate 2 in order and to be emitted as reflected light Lo.

  As shown in FIGS. 2A and 2B, the liquid crystal panel 4 is arranged such that the first substrate 6 and the second substrate 7 face each other. And the 1st board | substrate 6 and the 2nd board | substrate 7 are bonded together by adhere | attaching with the sealing material 8 formed in the frame shape. A liquid crystal layer 9 is formed in a region between the first substrate 6 and the second substrate 7 and surrounded by the sealant 8 by filling the region with liquid crystal. In the liquid crystal panel 4, a plurality of display pixels are arranged in a matrix in a display area 10 that is an area corresponding to most of the area where the liquid crystal layer 9 is formed.

  FIG. 3 is an equivalent circuit plan view of the thin film transistor array formed on the second substrate 7. On the second substrate 7, a plurality of pixel electrodes 11 are arranged in a matrix in the display region 10 so that one pixel electrode 11 corresponds to one display pixel. That is, a plurality of display pixels are arranged in a matrix. Each of the plurality of pixel electrodes 11 is connected to one of the source / drain electrodes in the thin film transistor 12 corresponding thereto, for example, the source electrode S. The other of the source / drain electrodes in the thin film transistor 12, for example, the drain electrode D, is connected to a signal line 13 extending along the column direction. Further, the gate electrode G in the thin film transistor 12 is connected to a scanning line 14 extending along the row direction. An auxiliary capacitance electrode 15 for forming an auxiliary capacitance Cs is formed between the pixel electrode 11 and the pixel electrode 11. The pixel electrode 11 is arranged so that a part of the pixel electrode 11 overlaps the auxiliary capacitance electrode 15. Here, the thin film transistor 12 functions as a switching element, and for example, an nMOS type thin film transistor can be used. The scanning line 14 is for supplying a scanning signal for on / off control of the thin film transistor 12 to the gate electrode G of the thin film transistor 12, and the signal line 13 is connected to the pixel electrode via the thin film transistor 12. 11 for supplying a data signal.

  Further, the signal line 13, the scanning line 14, and the auxiliary capacitance electrode 15 are extended to a region outside the display region 10. The signal line 13 is connected to a first external connection terminal 16 provided in an area outside the display area 10, and the scanning line 14 is a second external connection terminal provided in an area outside the display area 6. The auxiliary capacitance electrode 15 is connected to a third external connection terminal 18 provided in a region outside the display region 6. The auxiliary capacitance electrodes 15 are electrically connected to each other so that the display pixels have the same potential, and are also electrically connected to a common electrode 20 described later via the transformer pad 19. That is, the auxiliary capacitance electrode 15 is set to the same potential as the common electrode 20. Here, the first external connection terminal 16, the second external connection terminal 17, and the third external connection terminal 18 are externally connected via a flexible wiring board or the like by connecting a member such as a flexible wiring board or the like. Electrically connected to the circuit. For example, the first external connection terminal 16 is electrically connected to a data driver that outputs a data signal, the first external connection terminal 17 is electrically connected to a scan driver 18 that outputs a scan signal, and a third The external connection terminal 18 is electrically connected to a common driver that outputs a common signal. Note that FIG. 3 shows a case where display pixels are arranged by 3 columns × 3 rows for the sake of illustration, but for example, in the case of color display by XGA, the display pixels are 1024 × 3. It is arranged for columns × 768 rows.

  As shown in FIG. 2B, the first substrate 6 is provided with a color filter 21 and a common electrode 20 formed on the color filter. The color filter 21 includes a black mask 21m made of a light-shielding material, a red filter 21r that transmits light in the red wavelength region and also blocks light in the wavelength region of other colors, and transmits light in the green wavelength region. The green filter 21g shields light in the wavelength region of the blue color and the blue filter 21b transmits light in the blue wavelength region and shields light in the wavelength regions of other colors.

  The black mask 21m is formed in a lattice shape in which openings are provided at positions corresponding to the pixel electrodes 11. Filters as color components such as the red filter 21r, the green filter 21g, and the blue filter 21b are provided in the opening of the black mask 21m so that one color component corresponds to one display pixel. Here, the display pixel R provided with the red filter 21r, the display pixel G provided with the green filter 21g, and the display pixel B provided with the green filter 21g, as shown in FIG. Are arranged so as to be repeated with respect to the direction along the signal line 13, and are arranged so that display pixels on which the same color component is arranged are continuous with respect to the direction along the signal line 13. That is, the color filter 21 is formed in a so-called stripe arrangement. Then, the liquid crystal display device 1 performs color display for one dot in three display pixel units P that are continuous in the direction along the scanning line 14.

  Meanwhile, in the liquid crystal panel 4, the region corresponding to the opening of the black mask 21m has a second color component corresponding to the display pixel in the external light Li incident on the liquid crystal panel 4 from the first substrate 6 side. The external light Li emitted from the substrate 7 side toward the reflecting plate 5 and reflected by the reflecting plate 5 is incident again on the liquid crystal panel 4 from the second substrate 7 side and reflected light from the first substrate 6 side. It is configured to inject as Lo. That is, the first substrate 6 and the second substrate 7 are formed of a transparent insulating material such as glass, and the pixel electrode 11 and the common electrode 20 are formed of a transparent conductive material such as ITO. ing. In addition, the liquid crystal panel 4 is a first thin film (thin film in contact with the liquid crystal layer 5) among the thin films provided on the first substrate 6 in order to control the initial alignment state of the liquid crystal molecules in the liquid crystal layer 5. The second alignment film 23 is provided as the uppermost thin film (thin film in contact with the liquid crystal layer 5) of the thin films provided on the second substrate 7. The liquid crystal panel 4 changes the tilt angle and the azimuth angle as the alignment direction of the liquid crystal molecules by controlling the magnitude of the voltage applied between the pixel electrode 11 and the common electrode 20.

  The first polarizing plate 2 and the second polarizing plate 3 transmit one of the two polarization components orthogonal to each other and absorb the other. In the liquid crystal panel 4, for example, the first alignment film When the initial alignment is controlled so that the liquid crystal layer 9 is in the TN mode or the VA mode by the liquid crystal layer 22 and the second alignment film 23, they are arranged so that their polarization axes are orthogonal to each other. In the TN mode, a liquid crystal having a positive dielectric anisotropy is applied to the liquid crystal layer 9, and in the VA mode, a liquid crystal having a negative dielectric anisotropy is applied to the liquid crystal layer 9. By arranging the first polarizing plate 2 and the second polarizing plate 3 in this manner, the magnitude of the voltage applied between the pixel electrode 11 and the common electrode 20 is further controlled. As a result, the amount of external light Li incident from the first polarizing plate 2 toward the liquid crystal panel 4 is emitted from the second polarizing plate 3, and further from the second polarizing plate 3 toward the liquid crystal panel 4. The amount of light emitted from the first polarizing plate 2 in the reflected light from the reflecting plate 5 is controlled.

  As shown in FIGS. 5 (a), 5 (b), and 5 (c), the reflecting plate 5 is a base on which a plurality of first concave portions 51a having a shape corresponding to a part of the surface shape of a sphere are formed. A reflective layer 52 in which a second concave portion 52a corresponding to the first concave portion 51a is formed by forming the layer 51 so that the surface shape follows the surface shape of the base layer 51, and at least a part thereof A spherical refracting body 53 fitted into the second recess 52a so as to protrude from the second recess 52a. That is, the spherical refractor 53 is arranged on the base 51 so that the surface of the portion fitted in the first recess 51a is covered with the reflective layer 52 as the reflective metal 52 that reflects light. ing.

  Here, the first concave portion 51a and the second concave portion 52a are formed so as to correspond to a hemispherical shape so that a half region of the spherical refracting body 53 fits in close contact with the second concave portion 52a. Is formed.

  The diameter and refractive index of the spherical refracting body 53 are such that the reflecting plate 5 out of the external light Li incident through the first polarizing plate 2, the liquid crystal panel 4, and the second polarizing plate 3 in this order. The external light Lia incident in parallel to the normal line HL is reflected as reflected light Loa in parallel to the normal line HL and incident at an angle θ inclined with respect to the normal line HL of the reflector 5. The incoming external light Lib is set as reflected light Lob so as to be reflected at the angle at which the external light Lib is incident in the direction in which the external light Lib is incident. That is, the reflecting plate 5 is configured to reflect the external light Li so that the reflected light passes through the same path as the light incident path.

  Therefore, in the liquid crystal display device 1 according to the present embodiment, when the external light Li passes through the display panel 4, the same display pixel, that is, the same color, is provided between the forward path to the reflection plate 5 and the return path. Since the component filter can be passed, the rate of color mixing is suppressed, and an image with high display quality can be obtained.

  As shown in FIG. 6A, the first concave portion 51a and the second concave portion 52a are arranged so that the spherical refractors 53 are densely arranged with a half-pitch shift for each row. Alternatively, as shown in FIG. 6B, the spherical refractors 53 may be formed densely so as to be linearly arranged in each of the row direction and the column direction. In any case, the arrangement pitch of the refractive bodies 53 is preferably smaller than the arrangement pitch of the display pixels, and it is more preferable that 100 or more refractive bodies 53 are arranged for one display pixel.

  Hereinafter, the manufacturing method of the reflecting plate 5 as described above will be described. As shown in FIG. 7A, a thermoset resin 56 before curing is applied to a uniform thickness on a heat-resistant insulating substrate 55 such as glass, and a stamper in which hemispherical projections 57a are arranged. 57 is prepared. Next, as shown in FIG. 7 (b), the stamper 57 is pressed onto the thermosetting resin 56, and after a predetermined time, the pressing is released, and the thermosetting resin 56 is thermoset. Then, the base layer 51 made of the thermosetting resin 56 and the heat-resistant insulating substrate 55 in which the first concave portions 51a are formed as a transfer pattern of the convex portions 57a is formed.

  Next, as shown in FIG. 7C, a metal thin film having high light reflectivity such as aluminum or silver is formed on the surface of the base layer 51 by a vapor deposition method or a sputtering method, and the surface shape is the base layer. The film is formed to have a shape following the surface shape of 51. That is, the metal thin film is formed so as not to flatten the first recess 51a formed in the base layer 51 and to form the second recess 52a corresponding to the first recess 51a. .

  Next, a spherical refracting body 53 having a size that can be fitted into the second concave portion 52a is set in each of the second concave portions 52a by setting the diameter to be approximately equal to the diameter of the second concave portion 52a. . By the above method, the reflecting plate 5 shown in FIGS. 5B and 5C can be obtained.

  In order to make the adhesion between the second recess 52a and the refracting body 53 stronger, the following process may be added after the refracting body 53 is fitted into the second recess 52a. That is, a highly light reflective metal thin film such as aluminum or silver is formed again on the surface of the second recess 52a with the refractor 53 inserted therein. The metal thin film formed on the surface of the portion protruding from the second recess 52a is removed by etching. By performing such a process, the refractor 53 is sandwiched partially by the outer peripheral portion of the second recess 52a by the metal thin film formed first and the metal thin film formed second. The adhesion between the second recess 52a and the refracting body 53 can be made stronger.

  In the above-described manufacturing method, the reflective layer 52 is formed so that the surface shape of the reflective layer 52 follows the surface shape of the base layer 51, whereby the second concave portion 52a corresponding to the first concave portion 51a. However, the reflective layer 52 may be formed so as to cover the surface of the refractor 53 so that the second concave portion 52a corresponding to the first concave portion 51a may be formed. .

  That is, as shown in FIG. 7B, after forming the base layer 51 in which the first concave portion 51a is formed, as shown in FIG. 8A and FIG. A spherical refractor 53 whose surface is covered with a highly light-reflective metal thin film 58 is fitted into each of the first recesses 51a. At this time, the spherical refractor 53 whose surface is covered with the metal thin film 58 is formed so that the entire diameter thereof is approximately equal to the diameter of the first recess 51a, so that the spherical recess 53a can be fitted into the first recess 51a. Is set.

  The portion of the metal thin film 58 that protrudes from the first recess 51 a so that the portion of the metal thin film 58 a interposed between the base layer 51 and the refractive body 53 remains as the reflective layer 52. The metal thin film 58b covering the film is removed by etching. Also by the above manufacturing method, the reflector 5 as shown in FIG.5 (b) or FIG.5 (c) can be obtained. When the reflection plate 5 is formed in this way, the degree of adhesion between the refracting body 53 and the reflecting layer 52 is high, that is, no air layer is interposed between the refracting body 53 and the reflecting layer 52. In addition, the reflecting plate 5 can be formed.

  Here, the reflecting plate 5 is preferably arranged so that the surface of the refracting body 52 is in contact with the air layer. That is, it is preferable to dispose the reflecting plate 5 so that an air layer is interposed between the optical sheet disposed closest to the reflecting plate 5, for example, the second polarizing plate 3. When the external light is incident on the refracting body 52 or when the external light incident on the refracting body 52 is emitted from the refracting body 52, a large refraction angle can be obtained, and the degree of freedom in designing the reflector 5 can be increased. Can be big.

  Alternatively, the surface shape of the refractive body 52 may be protected by applying a transparent protective film having a refractive index lower than that of the refractive body 52 to the surface of the refractive body 52.

  In the above-described embodiment, the configuration in which the reflecting plate 5 is arranged so that the second polarizing plate 3 is interposed between the liquid crystal layer 9 is described. However, the liquid crystal layer 9 and the second polarizing plate 3 It is good also as a structure by which the reflecting plate 5 is arrange | positioned between.

  Although the present invention has been described based on the above embodiments, the present invention is not limited to the above-described embodiments, and various modifications and applications are possible within the scope of the gist of the present invention. is there.

  DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device, 2, 3 ... Polarizing plate, 4 ... Liquid crystal panel, 5 ... Reflecting plate, 21 ... Color filter, 51 ... Base layer, 52 ... Reflective layer (reflective metal), 53 ... Refraction body, Li, Lia, Lib ... external light, Lo, Loa, Lob ... reflected light

Claims (6)

A base layer in which a plurality of concave portions having a shape corresponding to a part of the surface shape of the sphere are formed;
A spherical refractor having a predetermined refractive index and fitted into the recess so that at least a portion protrudes from the recess;
With
The reflector is characterized in that the surface of the portion fitted in the recess is covered with a reflective metal that reflects light.   2. The reflector according to claim 1, wherein the refractor has a surface of a portion protruding from the recess exposed from the reflective metal.   The reflector according to claim 2, wherein the recess is formed in a shape corresponding to a hemisphere. A reflective layer in which at least the surface is made of a reflective metal that reflects light and a plurality of concave portions having a shape corresponding to a part of the surface shape of the sphere are formed;
A spherical refractor having a predetermined refractive index and fitted into the recess so that at least a portion protrudes from the recess;
A reflector characterized by comprising. A liquid crystal panel in which a liquid crystal layer is formed between the pixel electrode and the counter electrode;
A pair of polarizing plates arranged to sandwich the liquid crystal panel;
A reflector disposed so that one of the pair of polarizing plates is interposed between the display panel, and
With
The reflector is
A base layer in which a plurality of concave portions having a shape corresponding to a part of the surface shape of the sphere are formed;
A spherical refractor having a predetermined refractive index and fitted into the recess so that at least a portion protrudes from the recess;
With
The liquid crystal display device, wherein the surface of the portion of the refractor that is inserted into the recess is covered with a reflective metal that reflects light. A liquid crystal panel in which a liquid crystal layer is formed between the pixel electrode and the counter electrode;
A pair of polarizing plates arranged to sandwich the liquid crystal panel;
A reflector disposed so that one of the pair of polarizing plates is interposed between the display panel, and
With
The reflector is
A reflective layer in which at least the surface is made of a reflective metal that reflects light, and a plurality of concave portions having a shape corresponding to a part of the surface shape of the sphere are formed;
A spherical refractor having a predetermined refractive index and fitted into the recess so that at least a portion protrudes from the recess;
A liquid crystal display device comprising:

Images