JP2005099440A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transflective liquid crystal display device capable of increasing the luminance in transmission without increasing the brightness of a light source or making the aperture area of a reflecting film larger. <P>SOLUTION: Light reflected on the uneven surface 5a of a backlight 5 exits from the top surface of the backlight 5. Then, the light (illumination light) of the backlight 5 is made incident on individual converging lenses 45a constituting a lenticular lens 45. The illumination light G is condensed to the inside of a light shielding wall 35 demarcating individual pixels 36 through the converging operation of the converging lenses 45a. Consequently, illumination light which is lost by impinging on an area B of the light shield wall 35 demarcating the respective pixels 36 is greatly reduced and light emitted from the individual pixels 36 can be increased. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device including a liquid crystal display panel, a drive circuit that drives the display panel, and an illumination device that illuminates the display panel.

For example, as a liquid crystal display device widely used in electronic devices such as mobile phones and portable game machines, a lighting device such as a backlight is provided so that the liquid crystal display panel can be clearly observed even at night. In order to reduce power consumption, transflective liquid crystal display devices using external light as illumination light for liquid crystal display panels have been developed. As such a liquid crystal display device, one described in Patent Document 1 is known. In order to make this liquid crystal display device transflective, a reflective layer having an opening is provided in the vicinity of the liquid crystal layer, and specific examples of the opening include a slit-like or rectangular opening. Yes.
Japanese Patent No. 3235102

  By the way, in the above-described transflective liquid crystal display device, when the aperture area of the reflection film is increased in order to set the luminance at the time of transmission high (recently 40% to 50%), the reflected light from the reflection film at the time of reflection Decreases and the display becomes dark. Therefore, when the light source is brightened to increase the display brightness, there is a problem that the power consumption is significantly increased.

  The present invention has been made in view of the above circumstances, and an object thereof is to increase the luminance at the time of transmission without increasing the brightness of the light source and without increasing the opening area of the reflection film. Another object of the present invention is to provide a transflective liquid crystal display device.

  To achieve the above object, according to the present invention, a liquid crystal display panel having first and second substrates sandwiching a liquid crystal layer, an illuminating device that illuminates the liquid crystal display panel from the back side, and the first And a condensing lens provided corresponding to a pixel of the liquid crystal display panel and a driving circuit for driving the liquid crystal display panel. A liquid crystal display device is provided.

  According to such a liquid crystal display device, the illumination light that illuminates the liquid crystal display panel can be collected inside the light shielding wall that partitions each pixel by the condenser lens. As a result, the illumination light that is lost when hitting the light shielding walls that partition each pixel is greatly reduced, and as a result, the light emitted from each pixel can be increased. Therefore, the luminance of the liquid crystal display panel at the time of transmission can be improved and the visibility can be greatly improved without increasing the light consumption of the lighting device and increasing the battery consumption.

  The condensing lens may be a series of protrusion-shaped condensing lenses corresponding to the plurality of pixels arranged on the same line. The condensing lens may be formed in a quadrangular pyramid shape.

  The pixel only needs to have a color filter that sets the color of each pixel and an opening that sets the luminance of each pixel. The formation position of the condenser lens may be defined according to the incident angle of the illumination light emitted from the illumination device and the position of the pixel.

The drive circuit includes a γ correction circuit that γ corrects a color signal, an inversion circuit that inverts an output of the γ correction circuit at a timing of a horizontal synchronizing signal, and an output of the inversion circuit based on a luminance control signal. What comprises the control means to control is preferable.
According to this drive circuit, in the color display, even if a multi-tone (monochrome) signal is used for the luminance signal and a low-tone signal is used for the RGB color signal, the characteristics of the naked eye are used. An image can be displayed. As a result, the load on the circuit related to color signal processing can be reduced.

  According to the liquid crystal display device of the present invention, the illumination light that illuminates the liquid crystal display panel can be collected inside the light shielding wall that partitions each pixel by the condenser lens. As a result, the illumination light that is lost when hitting the light shielding walls that partition each pixel is greatly reduced, and as a result, the light emitted from each pixel can be increased. Therefore, the luminance of the liquid crystal display panel can be improved and the visibility can be greatly improved without increasing the light consumption of the lighting device and increasing the battery consumption.

  Further, according to the present invention, in the color display, the characteristic of the naked eye is used, that is, the multi-gradation of the image is given to the luminance signal (corresponding to the opening having no color filter), and the color signal (R , G, and B color filters) are displayed with fewer gradations, and are recognized as multi-gradation colors by the naked eye, so that a full-color image can be displayed. This has the effect of reducing the load on the circuit related to color signal processing.

  A transflective liquid crystal display device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an enlarged cross-sectional view showing an outline of a liquid crystal module 1 in the liquid crystal display device according to the embodiment. The liquid crystal module 1 is provided with a first substrate 10 made of transparent glass or the like and a second substrate 20 which are opposed to each other with a liquid crystal layer 30 interposed therebetween, and are annularly provided on the peripheral portions of the two substrates 10 and 20. The liquid crystal display panel 9 is bonded and integrated with a sealing material 40, and the backlight 5 is a lighting device.

  On the liquid crystal layer 30 side of the first substrate 10, the organic film 11 for forming a recess (dimple) 31 in the reflective film 12 and the light incident on the liquid crystal display device 1 are reflected, and from the backlight 5. The semi-transmissive reflective film 12 that transmits the light, the color filter 13 for performing color display, the organic film 11 and the semi-transmissive reflective film 12 are covered and protected, and the unevenness caused by the organic film 11 and the color filter 13 is flattened. An overcoat film 14 for forming the liquid crystal layer, an electrode layer 15 for driving the liquid crystal layer 30, and an alignment film 16 for controlling the alignment of liquid crystal molecules constituting the liquid crystal layer 30 are laminated. In addition, an electrode layer 25, an overcoat film 24, and an alignment film 26 are sequentially stacked on the liquid crystal layer 30 side of the second substrate 20.

  The color filter 13 may be formed by repeating three colors of R, G, and B, which are the three primary colors of light, for example. Between each color filter 13, a light shielding wall 35 generally called a black matrix is formed in order to prevent color mixture of light with the adjacent color filter 13.

  A lenticular lens 45, which will be described in detail later, is integrally formed on the surface of the first substrate 10 opposite to the liquid crystal layer 30 side (the outer surface side of the first substrate 10). A laminated body 18 of a polarizing plate and a retardation plate is provided below the lenticular lens 45. On the other hand, on the side opposite to the liquid crystal layer 30 side of the second substrate 20 (the outer surface side of the second substrate 20), a retardation film 27 and a polarizing plate 28 are laminated in this order. Further, outside the polarizing plate 18 of the first substrate 10, a backlight 5 is disposed as an illumination device for performing transmissive display in the liquid crystal display device 1.

  The organic film 11 is provided in order to efficiently scatter the reflected light by providing a concave portion 31 to the transflective film 12 formed thereon. By forming the recess 31 in the transflective film 12 in this way, it is possible to efficiently reflect the external light incident on the liquid crystal display device 1, so that a bright display during illumination by external light reflection can be realized. it can.

  The transflective film 12 is formed of a highly reflective metal thin film such as aluminum or silver. In the transflective film 12, openings 32 are formed corresponding to the respective pixels of the liquid crystal display panel 9. The openings 32 are for allowing the light irradiated from the backlight (illuminating device) 5 to pass through the transflective film 12 formed of a metal thin film or the like.

  With the above-described configuration, the liquid crystal module 1 reflects outside the opening 32 of the transflective film 12 formed of a metal thin film or the like when outside light N enters the liquid crystal display panel 9, for example, outdoors during the daytime. Reflected by the area, the liquid crystal display panel 9 is brightly illuminated. On the other hand, in an environment where there is insufficient outside light such as at night or in a dark room, when the backlight 5 is turned on, the illumination light B emitted from the backlight 5 passes through the opening 32 of the transflective film 12 and is liquid crystal. The display panel 9 is brightly illuminated. As described above, the liquid crystal module 1 can illuminate the liquid crystal display panel 9 with high brightness and brightness by the action of the semi-transmissive reflective film 12 regardless of whether the external light or the backlight 5 is used as the light source.

  FIG. 2 is a perspective view showing a portion including the organic film 11 and the transflective film 12 formed thereon. As shown in this figure, on the surface of the organic film 11, a large number of concave portions 11a whose inner surface forms a part of a spherical surface are continuously formed so as to overlap with each other on the left and right sides. A film 12 is laminated. A recess 31 is formed in the transflective film 12 by the recess 11 a formed on the surface of the organic film 11. Further, for example, a rectangular opening 32 is formed in a part of the transflective film 12. Such an opening 32 may be formed by etching, for example.

  For example, the recesses 31 are randomly formed with a depth in the range of 0.1 μm to 3 μm, the pitches of the adjacent recesses 31 are randomly arranged in the range of 3 μm to 50 μm, and the inclination angle of the inner surface of the recess 31 is −30 degrees to It is desirable to set in the range of +30 degrees. In particular, it is particularly important that the inclination angle distribution of the inner surface of the recess 31 is set in a range of −30 degrees to +30 degrees and that the pitch of the adjacent recesses 31 is randomly arranged in all directions in the plane. This is because, if the pitch between the adjacent recesses 31 is regular, there is a problem that the interference color of light is emitted and the reflected light is colored.

  On the other hand, if the inclination angle distribution on the inner surface of the recess 31 exceeds the range of -30 degrees to 30 degrees, the diffusion angle of the reflected light is excessively widened, the reflection intensity is lowered, and a bright display cannot be obtained (the diffusion angle of the reflected light). This is because it becomes 36 degrees or more in the air, the reflection intensity peak inside the liquid crystal display device decreases, and the total reflection loss increases. Further, when the depth of the recess 31 exceeds 3 μm, when the recess 31 is planarized in a subsequent process, the top of the projection cannot be filled with the planarization film (overcoat film 14), and an extremely thick planarization film is used. Otherwise, the desired flatness cannot be obtained, causing display unevenness. When a thick flattening film is used, the flattening film is likely to be shrunk or clarified due to coloring or a reliability test.

  When the pitch of the adjacent recesses 31 is less than 3 μm, there is a restriction on the production of a transfer mold used to form the organic film 11, and the processing time is extremely long, and a shape capable of obtaining desired reflection characteristics is formed. Inability to generate interference light occurs. In practice, when a diamond indenter having a diameter of 30 μm to 100 μm that can be used for manufacturing the transfer mold is used, it is desirable that the pitch of the adjacent recesses 31 be 5 μm to 50 μm.

  With such a configuration, the semi-transmissive reflective film 12 transmits the illumination light B from the backlight 5 through the opening 32 and can efficiently reflect the external light N in the reflective region 33 in which many concave portions 31 are formed. .

  FIG. 3A is an enlarged plan view of an enlarged view of each pixel of the liquid crystal display panel, and FIG. 3B is a side cross-sectional view corresponding to FIG. 3A. Each pixel 36 of the liquid crystal display panel 9 indicated by a chain line is composed of R, G, and B color filters 13R, 13G, and 13B, a light transmitting portion 46, and a light shielding wall (black matrix) 35 that partitions them. Has been.

  The translucent part 46, which is an aperture that gives brightness to each pixel and sets it, directs white light such as light from the backlight 5 and external light reflected by the semi-transmissive reflective film 12 as it is toward the liquid crystal display panel 9. The transparent portion 46 and the R, G, and B color filters 13R, 13G, and 13B perform multi-tone representation of each color, thereby realizing multi-tone full-color display also called LRGB.

  The transflective film 12 formed below each of the color filters 13R, 13G, 13B and the translucent portion 46 has a backlight 5 at a position corresponding to each of the color filters 13R, 13G, 13B and the translucent portion 46. Each of the rectangular openings 32 is formed so as to transmit light from each of them.

  A lenticular lens 45 is integrally formed on the lower layer surface (backlight 5 side) of the first substrate 10. FIG. 4 is an external perspective view of the first substrate 10 when viewed from the lower surface side. The lenticular lens 45 integrally formed on the lower surface of the first substrate 10 is a sheet-like lens in which a large number of condensing lenses 45a (cylindrical lenses) having a substantially semicircular cross section extending in one direction are aligned. Each condenser lens 45a swells toward the backlight 5 side (see FIG. 3), and converges the light incident from the backlight 5 side toward the center of each condenser lens 45a.

  The individual condensing lenses 45a constituting the lenticular lens 45 are formed so as to correspond to one row of pixels 36U arranged on one line of the liquid crystal display panel 9. Thereby, the light incident on the individual condenser lenses 45 a converges toward the respective pixels 36.

  Next, the operation of such a condensing lens 45a (lenticular lens 45) will be described. As shown in FIG. 5, the light reflected by the uneven surface 5 a of the backlight 5 is emitted from the upper surface of the backlight 5. Then, the light (illumination light) of the backlight 5 is incident on the individual condenser lenses 45 a constituting the lenticular lens 45.

  The light incident on the condensing lens 45a is inclined from the vertical direction by the inclination of the uneven surface 5a. For this reason, if the light is incident as it is, light cannot be collected at the optimum position of each pixel 36, resulting in a loss. However, the center S1 of each condenser lens 45a is shifted from the center S2 of each pixel 36 by a width M corresponding to the inclination angle of the light incident on the condenser lens 45a. (See FIG. 3) The illumination light G can be collected inside the light shielding wall 35 that partitions each pixel 36 by the light condensing action of the condensing lens 45a.

  As a result, even if the light incident on the condenser lens 45a is tilted from the vertical direction, the illumination light that is lost when hitting the region B of the light shielding wall 35 that divides each pixel 36 is greatly reduced. The light emitted from each pixel 36 can be increased. Therefore, the luminance of the liquid crystal display panel 9 can be improved and the visibility can be greatly enhanced without increasing the battery consumption by increasing the light amount of the backlight 5.

  Next, a panel drive circuit that drives the liquid crystal panel 9 will be described. FIG. 7 is a block diagram showing the configuration of the panel drive circuit 70. In the figure, a luminance signal Y and a color signal C (both digital signals) of a video signal are input to a luminance signal correction circuit 71 and a color signal correction circuit 72, respectively. The luminance signal correction circuit 71 corrects the image quality and contrast of the luminance signal Y and outputs it. The color signal correction circuit 72 corrects the color level of the color signal C and outputs it to the color demodulator 73 and the automatic phase control circuit 74.

  The automatic phase control circuit 74 generates a carrier for demodulating the color signal C and outputs it to the color demodulator 73. The color demodulator 73 demodulates the color signal C to generate color difference signals R-Y, G-Y, and BY. Then, the color difference signal RY is output to the γ correction circuit 75R. The γ correction circuit 75R generates the color data R (red) by adding the color difference signal RY and the output of the luminance signal correction circuit 71, and then the γ according to the characteristics of the liquid crystal panel 9 to the color data R. Correction is performed and output to the inverting circuit 76R. The inversion circuit 76R inverts the output data R of the γ correction circuit 75R based on the horizontal synchronization signal from the timing signal generation circuit 80 and outputs the inverted data to the D / A converter 77R. Here, inversion means that LSB is replaced with MSB, (LSB-1) is replaced with (MSB-1), and so on. The D / A converter 77R converts the output data of the inverting circuit 76R into an analog R color signal and outputs it to the operational amplifier 78R.

  The timing signal generation circuit 80 generates a horizontal synchronization signal, a vertical synchronization signal, and other timing signals based on the luminance signal Y, and outputs them to each unit. The luminance control signal generator 81 generates control data for controlling the luminance level and outputs it to the D / A converter 82. The D / A converter 82 converts the output data of the luminance control signal generator 81 into an analog luminance level control signal and outputs it to the operational amplifier 78R. The operational amplifier 78R converts the level of the R color signal output from the D / A converter 77R according to the luminance level control signal output from the D / A converter 82, and outputs it to the liquid crystal panel 9.

  Similarly to the above, the color difference signals G-Y and BY output from the color demodulator 73 are also converted into color data G (green) and B (blue), γ correction is performed, inversion processing is performed, The signal is D / A converted, level-converted in accordance with the luminance level control signal, and output to the liquid crystal panel 9. Thereby, color display of the liquid crystal panel 9 is performed.

  In FIG. 1, the condensing lens that converges the illumination light on the inner side of the light shielding wall that partitions the pixels may be, for example, a prism shape such as a quadrangular pyramid. FIG. 6 shows a second embodiment of the present invention. In this embodiment, each condensing lens 61 is formed in a quadrangular pyramid shape, and one condensing lens 61 is arranged to correspond to one pixel 62 on a one-to-one basis.

  Such a condensing lens 61 can also converge the illumination light inside the light shielding wall 63 of each pixel 62, so that the illumination light hits the light shielding wall 63 that partitions each pixel 62 and causes a loss. This can be prevented and the light emitted from each pixel 62 can be increased.

  In the above-described embodiments, the transflective liquid crystal display device is taken up. However, the present invention is not limited to this, and a transmissive liquid crystal display device that illuminates the liquid crystal display panel only with illumination light from the illumination device. It may be. The condensing lens is not limited to the semi-circular cross section or square pyramid shape described above, but may be any shape having a condensing function, such as a substantially hemispherical convex lens or a trapezoidal prism. There may be.

  Moreover, the said condensing lens should just be a series of condensing lenses which condense with respect to each of the said several pixel located in a line with the same line. In addition, the pixels need only be formed with a color filter that sets the color of each pixel and an opening that sets the luminance of each pixel.

It is sectional drawing which shows the structure of the liquid crystal module in the liquid crystal display device by one Embodiment of this invention. It is an expansion perspective view of the semi-transmissive reflective film shown in FIG. It is explanatory drawing which shows the relationship between each pixel and a condensing lens. It is an external appearance perspective view which shows the mode of the 1st board | substrate with which the condensing lens was formed. It is explanatory drawing explaining the effect | action of the liquid crystal module of the embodiment. It is an external appearance perspective view which shows other embodiment of this invention. It is a block diagram which shows the structure of the panel drive circuit which drives the liquid crystal panel 9 shown in FIG.

Explanation of symbols

1 Liquid crystal display device 5 Backlight (lighting device)
9 Liquid crystal display panel 10 Substrate (first substrate)
12 Transflective film 13 Color filter 20 Substrate (second substrate)
31 Concavity (dimple)
32 aperture 36 pixel 45a condenser lens 70 panel beat circuit 71 luminance signal correction circuit 72 color signal correction circuit 73 color demodulator 74 automatic phase control circuit 75R gamma correction circuit 76R inversion circuit 77R, 82 D / A converter 78R operational amplifier 80 timing Signal generation circuit 81 Luminance control signal generator

Claims (6)

A liquid crystal display panel having first and second substrates sandwiching a liquid crystal layer, and an illumination device for illuminating the liquid crystal display panel from the back side;
A condensing lens provided on the surface of the substrate closer to the illumination device among the first and second substrates, corresponding to the pixels of the liquid crystal display panel;
A drive circuit for driving the liquid crystal display panel;
A liquid crystal display device comprising: The liquid crystal display device according to claim 1, wherein the condensing lens is a series of protrusion-shaped condensing lenses corresponding to the plurality of pixels arranged on the same line. The liquid crystal display device according to claim 1, wherein the condensing lens is formed in a quadrangular pyramid shape. 4. The color filter for setting the color of each pixel and an opening for setting the luminance of each pixel are formed in the pixel. Liquid crystal display device. The formation position of the condensing lens is defined according to the incident angle of the illumination light emitted from the illumination device and the position of the pixel. The liquid crystal display device according to the item. The drive circuit performs γ correction on a color signal, an inverting circuit that inverts an output of the γ correction circuit at a timing of a horizontal synchronization signal, and level-controls the output of the inverting circuit based on a luminance control signal. The liquid crystal display device according to claim 1, further comprising a control unit.

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