JP2010039113A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device which is excellent in brightness and achieves high efficiency. <P>SOLUTION: The liquid crystal display device is provided with: a liquid crystal panel which has a plurality of display cells and makes light incident from a light-incident face, modulates the light for each display cell, and emits the light from a display face; a light source part having at least one or more light sources; a light-separating means which separates light from the light source part into light corresponding to the wavelength bands of red color, green color and blue color, respectively; a plurality of relay lenses which are provided for each wavelength band, have their own optical axes located on the same plane, and magnify and project the light of the respective wavelength bands as the incident images, the light concerned being separated by the light-separating means; a Fresnel lens which is provided in the vicinities of the magnification-side focal distances of the plurality of relay lenses and refracts the light path of the incident light in the normal direction of the display face side of the liquid crystal display panel; and a wrench killer lens which converges the light of the respective wavelength bands emitted from the Fresnel lens on different positions in the vicinity of the light-incident face of the liquid crystal display panel. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device for realizing bright and high efficiency.

  The liquid crystal display device requires a backlight for irradiating light from the back surface. Conventionally, a cold cathode tube or the like is used as a light source of the backlight. Recently, LEDs have also been used.

  When the liquid crystal display device is used in a bright environment, the luminance increases due to the reflection of external light even if the liquid crystal display device performs a black display operation. For this reason, the brightness difference from the white display operation is reduced, and only a low contrast image can be reproduced.

  In order to display an image with high contrast in a bright environment, it is necessary to improve the brightness during white display. In the case of a cold cathode tube, the output and the number thereof are increased.

As a backlight illumination system for guiding an illumination beam with a lens as a backlight illumination system, for example, a backlight illumination system for a liquid crystal display device proposed in Patent Document 1 has been proposed.
JP 2007-171976 A

  In Patent Document 1, a discharge lamp or the like is assumed as a light source. Therefore, an output larger than that of the cold cathode tube can be obtained, and the liquid crystal display device can be brightened. However, the efficiency of the liquid crystal display device is not necessarily high.

  In the liquid crystal display device, a color filter is arranged for each display cell in order to obtain a color image. Light rays that could not pass through the color filter are absorbed by the color filter, causing a significant reduction in efficiency. Each display cell is partitioned by a band called a black matrix that absorbs light. For this reason, the light absorbed by the black matrix is not used for display, which greatly reduces the efficiency.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a bright and high-efficiency liquid crystal display device.

  In order to achieve the above object, a liquid crystal display device of the present invention has a plurality of display cells, a liquid crystal panel that receives light from an incident surface, modulates light for each display cell, and emits the light from the display surface; A light source unit having at least one light source, light separating means for separating light from the light source unit into light of each wavelength band of red, green, and blue, and each light provided for each wavelength band A plurality of relay lenses whose axes are positioned in the same plane, and which enlarge and project a primary image formed by light of each wavelength band separated by the light separating means as a secondary image; and two of the plurality of relay lenses A Fresnel lens that is provided in the vicinity of the next image position and refracts the optical path of the incident light toward the normal direction of the display surface of the liquid crystal panel; Lens that collect light at different positions Is provided with a killer lens, the.

  According to the present invention, it is possible to provide a liquid crystal display device that realizes bright and high efficiency.

(Embodiment 1)
A liquid crystal display device 10 according to Embodiment 1 of the present invention will be described with reference to the drawings.

<1. Configuration of liquid crystal display device>
FIG. 1 is a configuration diagram of a liquid crystal display device 10 according to the first embodiment.

  The liquid crystal display device 10 includes a light source unit 100, a light separation unit 200, relay lenses 301, 302, and 303, a Fresnel lens 401, a lenticular killer lens 501, and a liquid crystal panel 601.

  The light source unit 100 includes a discharge lamp 101 as a light source and an ellipsoidal mirror 102.

  The light separating means 200 reflects the red wavelength band and transmits the other wavelength band, and of the light transmitted through the dichroic mirror 201, reflects the green wavelength band and transmits the other wavelength band. And a mirror 203 that reflects the light transmitted through the dichroic mirror 202. In addition, there are lot lenses 211, 212, and 213 that each color light reflected by the dichroic mirrors 201 and 202 and the mirror 203 is incident from the incident surface, and the respective light intensity distributions are uniformed and emitted from the emission surface. ing. With this configuration, the light separating unit 200 spatially separates the light from the light source unit 100 into light of each color wavelength band.

  The relay lenses 301, 302, and 303 are arranged side by side in the y-axis direction of FIG. 1, and each optical axis is located in the same plane (in the xy plane). The relay lenses 301, 302, and 303 enlarge and project the primary images of the emission end faces of the lot lenses 211, 212, and 213 as secondary images on the Fresnel lens 401.

  The Fresnel lens 401 irradiates the light of each color that has been enlarged and projected onto the back surface (incident surface) of the liquid crystal panel 601. At this time, the light is refracted and irradiated on the display surface normal direction side (x-axis direction side) of the liquid crystal panel 601. Although FIG. 1 shows a cross-sectional configuration, the Fresnel lens 401 has a surface shape parallel to the yz plane having an area for irradiating the entire back surface of the liquid crystal panel 601.

  Note that the optical axis of the Fresnel lens 401 coincides with the optical axis of the relay lens 302. With this configuration, the image circle of the relay lens is minimized.

  The wrench killer lens 501 has a plurality of cylindrical lens portions having a generating line in the z direction. That is, the direction of the generatrix of the cylindrical lens unit is orthogonal to the plane (xy plane) including the optical axes of the relay lenses 301, 302, and 303. The wrench killer lens 501 condenses the light of each color emitted from the Fresnel lens 401 on the back surface (incident surface) of the liquid crystal panel 601. At this time, the lenticular killer lens 501 focuses the light of each color incident at another position on the incident surface of the liquid crystal panel 601. That is, light separated by each color is incident on the liquid crystal panel 601.

  The liquid crystal panel 601 has a plurality of display cells corresponding to blue, green, and red. In FIG. 1, when blue, green, and red display cells are arranged in the y direction to form one set, they are arranged in a matrix in the y direction and the z direction. That is, display cells having the same color are arranged in the z direction, and blue, green, and red display cell columns are sequentially arranged in the y direction. Here, a cylindrical lens portion of one row of the lenticular killer lens 501 is configured to face three rows of display cells made of blue, green, and red of the liquid crystal panel 601.

  The configuration of the liquid crystal display device 10 has been described above.

<2. Operation of liquid crystal display device>
Next, the operation of the liquid crystal display device 10 will be described.

  In the light source unit 100, the light emitted from the discharge lamp 101 is reflected by the ellipsoidal mirror 102 and travels to the light separating means 200.

  FIG. 2 is an explanatory diagram for explaining the light separating action of the light separating means 200.

  The light incident on the light separating means 200 is first reflected by the dichroic mirror 201 in the red wavelength band component in the x-axis direction. The reflected light in the red wavelength band is collected at the focal position of the ellipsoidal mirror 102. There is an incident end face of the lot lens 211 at the condensing position, and the light enters the lot lens 211. The light in the red wavelength band incident on the lot lens 211 repeats total reflection and travels toward the exit end face of the lot lens 211. By repeating the total reflection, the emission end surface of the rod lens 211 becomes a uniform brightness surface with reduced unevenness. The light transmitted through the dichroic mirror 201 without being reflected is reflected by the dichroic mirror 202 at the green wavelength band component. Then, an output end face having uniform brightness is formed by the action of the lot lens 212. Further, the light in the blue wavelength band that has passed through the dichroic mirror 202 without being reflected is reflected by the mirror 203. Similarly, an exit end face with uniform brightness is formed by the action of the lot lens 213.

  Here, the position in the y-axis direction where the light from the light source unit 100 is bent is different between the dichroic mirror 201, the dichroic mirror 202, and the mirror 203. Therefore, when the incident end faces of the lot lenses 211, 212, and 213 are placed at the condensing position of the ellipsoidal mirror 102, if the lengths of the lot lenses 211, 212, and 213 are the same, the exit of the lot lenses 211, 212, and 213 The positions of the end faces are not aligned in the x-axis direction. When the positions of the exit end faces of the lot lenses 211, 212, and 213 are not aligned, the relay lenses 301, 302, and 303 that are formed thereafter require different focal lengths. Therefore, the configuration of the liquid crystal display device 10 is complicated. In the present embodiment, the positions of the exit end faces of the lot lenses 211, 212, and 213 are aligned by changing the lengths of the lot lenses 211, 212, and 213. As a result, the configuration can be simplified.

  The light image of the uniform red wavelength band on the exit end surface of the lot lens 211 is enlarged and projected by the relay lens 301 to a size that substantially matches the size of the incident surface of the liquid crystal panel 601. Similarly, light in the green and blue wavelength bands is enlarged and projected by the relay lens 302 and the relay lens 303. The focal lengths of the relay lenses 301, 302, and 303 are substantially the same, and the Fresnel lens 401 is positioned there.

  Images magnified and projected by the relay lenses 301, 302, and 303 are refracted by the Fresnel lens 401 toward the display surface side (x-axis direction side) of the liquid crystal panel 601. Then, the light refracted and incident on the lenticular lens 501 is separated into each color.

  In this embodiment, the relay lenses 301, 302, and 303 and the Fresnel lens 401 form a double-sided telecentric optical system, so that the luminance at the center and the periphery on the incident surface of the liquid crystal panel 601 is made more uniform. ing.

  Here, the operation of separating light into each color by the lenticular killer lens 501 will be described with reference to FIGS.

  FIG. 3 is an explanatory diagram for explaining an optical path from the relay lenses 301, 302, and 303 to the liquid crystal panel 601. Note that the relay lenses 301, 302, and 303 illuminate the entire surface of the Fresnel lens 401, but FIG. 3 shows only the optical path that reaches the vicinity of the center and the lower end.

  The Fresnel lens 401 is illuminated with light of each color from the relay lenses 301, 302, and 303, but the angles of the incident light beams are different. In the wrench killer lens 501, the position of the condensed light beam changes due to the difference in the angle of the light beam, and the light beam is separated for each relay lens.

  In the present embodiment, the optical axes of the relay lenses 301, 302, and 303 are arranged so as to be in the same plane, and the generatrix of the cylindrical lens portion of the lenticular lens 501 is on that plane. Orthogonal. With this configuration, the angle of light of each color incident on the cylindrical lens portion of the lenticular killer lens 501 is changed, so that the light can be easily separated.

  FIG. 4 is an explanatory diagram for explaining the optical path from the relay lens 302 to the lower end of the Fresnel lens 401 in more detail.

  The optical path of the light emitted from the relay lens 302 is refracted by the Fresnel lens 401 and is substantially in the display surface normal direction (x-axis direction) of the liquid crystal panel 601. The light emitted from the Fresnel lens 401 enters the incident surface of the lenticular killer lens 501, is refracted, and is collected on the exit surface of the lenticular killer lens 501. Since the liquid crystal panel 601 is placed in the vicinity of the exit surface of the wrench killer lens 501, the luminous flux when passing through the liquid crystal panel becomes narrow and passes through the green display cell 611 divided by the black matrix 614.

  FIG. 5 is an explanatory diagram for explaining the optical path from the relay lens 303 to the lower end of the Fresnel lens 401 in more detail.

  The optical path of the light emitted from the relay lens 303 is refracted by the Fresnel lens 401 more than when the relay lens 302 is used. Then, the light emitted from the Fresnel lens 401 enters from the lower surface of the drawing on the entrance surface of the lenticular lens 501, is refracted, and is collected on the exit surface of the lenticular lens 501. This condensing position is on the upper side of the drawing compared to the relay lens 302. In the case of the relay lens 302, since it was in the vicinity of the optical axis of the exit surface of the lenticular killer lens, it was not subjected to the refractive action. However, in the case of the light from the relay lens 303, the light is condensed at a position away from the optical axis. In response, the chief ray coincides with the normal direction of the display surface of the liquid crystal panel 601. Since the liquid crystal panel 601 is placed in the vicinity of the exit surface of the lenticular killer lens 501, the luminous flux when passing through the liquid crystal panel 601 becomes thin and passes through the blue display cells 612 separated by the black matrix 614.

  FIG. 6 is an explanatory diagram for explaining the optical path from the relay lens 301 to the lower end of the Fresnel lens 401 in more detail.

  The optical path of the light emitted from the relay lens 301 is refracted smaller by the Fresnel lens 401 than when the relay lens 302 is used. Then, the light emitted from the Fresnel lens 401 enters from the upper side of the drawing on the incident surface of the lenticular lens 501, is refracted, and is collected on the exit surface of the lenticular lens 501. This condensing position is on the lower side of the drawing as compared with the relay lens 302. In the case of the relay lens 302, since it was in the vicinity of the optical axis of the exit surface of the lenticular killer lens, it was not subjected to the refraction action. However, in the case of the light from the relay lens 301, the light is condensed at a position away from the optical axis. In response, the chief ray coincides with the normal direction of the display surface of the liquid crystal panel 601. Since the liquid crystal panel 601 is placed in the vicinity of the exit surface of the wrench killer lens 501, the light flux passing through the liquid crystal panel 601 becomes narrower and passes through the red display cells 613 separated by the black matrix 614.

  By such an operation, the separated light of each color enters the incident surface of the liquid crystal panel 601 and the light of each color is transmitted to each display cell. Therefore, since color separation can be performed without disposing color filters for each color on the liquid crystal panel 601, high efficiency can be achieved. Further, since the light separated into the wavelength bands of the respective colors is condensed on each display cell, the light absorbed by the black matrix provided between the display cells is reduced, and also in this respect, high efficiency is achieved. It is possible.

  The operation of the liquid crystal display device 10 has been described above.

  In the present embodiment, a configuration in which one white light can be spatially separated in the wavelength band by using a dichroic mirror is easily realized, but the present invention is not limited to this. In short, other configurations may be used as long as light can be separated for each wavelength band.

  In the present embodiment, a configuration that can easily make the light intensity distribution uniform by using a lot lens is realized, but the present invention is not limited to this. For example, an illumination system using a multi-lens array may be used. In short, other configurations may be used as long as the light intensity distribution can be made uniform.

  In the present embodiment, the discharge lamp and the ellipsoidal mirror are used as the light source unit, but the present invention is not limited to this. For example, a discharge lamp and a condenser lens may be used. However, the use of a discharge lamp and an ellipsoidal mirror allows a more compact configuration than when a condensing lens or the like is used.

  In the present embodiment, the lenticular killer lens and the liquid crystal panel are configured as separate bodies, but they can also be integrated. In this way, it is possible to reduce the size and to easily adjust the condensing position.

(Embodiment 2)
A liquid crystal display device according to Embodiment 2 of the present invention will be described with reference to the drawings.

  The liquid crystal display device of the second embodiment is different from the liquid crystal display device of the first embodiment in that the optical axes of the relay lenses 301 and 303 do not coincide with the lot lenses 211 and 213 of the light separating means. Other configurations are the same as those in the first embodiment.

  FIG. 7 is a configuration diagram of the light separating means 200 and the relay lenses 301, 302, and 303 in the liquid crystal display device according to the second embodiment.

  In the liquid crystal display device 10 according to the first embodiment, strictly speaking, the illumination area formed by the lot lens 211 and the relay lens 301 is illustrated with respect to the illumination area formed by the lot lens 212 and the relay lens 302. The illumination area formed by the lot lens 213 and the relay lens 303 is shifted to the lower side of the drawing. Accordingly, there are regions where some of the colors are not irradiated at the upper and lower ends of the irradiation region. The light in this region cannot be used as it is as the light incident on the liquid crystal panel 601.

  In the present embodiment, the same area as the illumination area formed by the lot lens 212 and the relay lens 302 is irradiated by shifting the optical axis of the relay lens 301 below the optical axis of the lot lens 211. Can do. Similarly, by shifting the optical axis of the relay lens 303 above the optical axis of the lot lens 213, the same area as the illumination area formed by the lot lens 212 and the relay lens 302 can be irradiated. With such a configuration, it is possible to eliminate regions where some of the colors are not irradiated at the upper and lower ends of the irradiation region, and it is possible to configure a more efficient liquid crystal display device.

  In the present embodiment, the lot lens 212 and the relay lens 302 have the same optical axes and are shifted from each other. However, the present invention is not limited to this. For example, the configuration may be such that the optical axes of the lot lens 211 and the relay lens 301 are coincident with each other and the others are shifted. However, by making the optical axes of the lot lens 212 and the relay lens 302 positioned in the middle coincide with each other, it is possible to minimize the shift width when shifting the others.

(Embodiment 3)
A liquid crystal display device according to Embodiment 3 of the present invention will be described with reference to the drawings.

  The liquid crystal display device of the third embodiment is different from the liquid crystal display device of the first embodiment in that the optical axes of the light beams in the respective wavelength bands separated by the light separating means are inclined with respect to each other. Other configurations are the same as those in the first embodiment.

  FIG. 8 is a configuration diagram of the light separating means 200 and the relay lenses 301, 302, and 303 in the liquid crystal display device according to the third embodiment.

  In the liquid crystal display device according to the present embodiment, the optical axis of the light reflected by the dichroic mirror 201 is below the drawing with respect to the optical axis of the light reflected by the dichroic mirror 202, and The optical axis is configured to be inclined on the upper side of the drawing. With this configuration, the optical axis of the lot lens 212 and the optical axes of the lot lenses 211 and 213 intersect with each other in the vicinity of the liquid crystal panel 601.

  With this configuration, with respect to the illumination area formed by the lot lens 212 and the relay lens 302, the illumination area formed by the lot lens 211 and the relay lens 301, and the illumination formed by the lot lens 213 and the relay lens 303. Each of the regions can be substantially matched.

  According to the liquid crystal display device of the present embodiment, there is no need to shift the optical axis of the relay lens and the optical axis of the lot lens as shown in the second embodiment. Therefore, the image circle of the relay lenses 301 and 303 can be reduced, and the relay lenses 301 and 303 can be configured compactly.

  In the present embodiment, the optical axis of the light reflected by the dichroic mirror 201 is on the lower side and the optical axis of the light reflected by the mirror 203 is on the upper side with respect to the optical axis of the light reflected by the dichroic mirror 202. Although the structure which inclines each was taken, it is not restricted to this. For example, the optical axis of the light reflected by the dichroic mirror 201 may not be tilted, and the light reflected by the dichroic mirror 202 and the mirror 203 may be tilted upward. However, by not tilting the optical axis of the light reflected by the dichroic mirror 202 located in the middle, it is possible to minimize the tilt angle when tilting others.

  In the liquid crystal display devices according to the first and second embodiments, the cross-sectional shapes of the rod lenses 211, 212, and 213 are preferably rectangular. This is to make it coincide with the rectangular display surface of the liquid crystal panel 601 with high accuracy. However, in the case of the liquid crystal display device according to the third embodiment, the light that is enlarged and projected onto the Fresnel lens 401 causes a trapezoidal distortion because the optical axis is inclined. In order to correct this, the cross-sectional shapes of the rod lens 211 and the lot lens 213 are preferably trapezoidal. With this configuration, it is possible to match the illumination areas with high accuracy also in the liquid crystal display device of the third embodiment.

  The liquid crystal display device according to the present invention is useful as a liquid crystal display device that is bright and highly efficient.

Configuration diagram of liquid crystal display device according to Embodiment 1 Explanatory drawing for demonstrating the light separation effect | action of the light separation means of Embodiment 1. FIG. Explanatory drawing for demonstrating the optical path from a relay lens to a liquid crystal panel in Embodiment 1. FIG. Explanatory drawing for explaining the optical path from the relay lens 302 to the lower end of the Fresnel lens 401 in more detail in the first embodiment. Explanatory drawing for explaining the optical path from the relay lens 303 to the lower end of the Fresnel lens 401 in more detail in the first embodiment. Explanatory drawing for explaining the optical path from the relay lens 301 to the lower end of the Fresnel lens 401 in more detail in the first embodiment. Configuration diagram of light separation means and relay lens of embodiment 2 of the present invention Configuration diagram of light separating means and relay lens of embodiment 3 of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Liquid crystal display device 100 Light source part 101 Discharge lamp 102 Ellipsoidal mirror 200 Light separation means 201, 202 Dichroic mirror 203 Mirror 211, 212, 213 Lot lens 301, 302, 303 Relay lens 401 Fresnel lens 501 Lenticular killer lens 601 Liquid crystal panel 611 , 612, 613 Display cell 614 Black matrix

Claims (13)

A liquid crystal panel having a plurality of display cells, injecting light from an incident surface, modulating the light for each display cell, and emitting from the display surface;
A light source unit having at least one light source;
A light separating means for separating light from the light source unit into light of each wavelength band of red, green, and blue;
A plurality of primary images, each of which is provided for each wavelength band, and in which each optical axis is positioned on the same plane, and a primary image formed by light of each wavelength band separated by the light separating means is enlarged and projected as a secondary image; A relay lens,
A Fresnel lens that is provided near the secondary image position of the plurality of relay lenses and refracts the optical path of the incident light toward the display surface normal direction side of the liquid crystal panel;
A lenticular killer lens that collects the light of each wavelength band emitted from the Fresnel lens at different positions in the vicinity of the liquid crystal panel incident surface, and
Liquid crystal display device. The wrench killer lens is
A plurality of cylindrical lens portions;
Three rows of display cells of the liquid crystal panel are opposed to one row of cylindrical lens portions.
The liquid crystal display device according to claim 1. A generatrix of the lenticular killer lens is orthogonal to a plane including an optical axis of the plurality of relay lenses,
The liquid crystal display device according to claim 1. The optical axis of the Fresnel lens coincides with the optical axis of the central relay lens among the plurality of relay lenses.
The liquid crystal display device according to claim 1. The relay lens and the Fresnel lens form a bilateral telecentric optical system;
The liquid crystal display device according to claim 1. At least one of the optical axes of the relay lenses corresponding to the optical axes of the light beams in the respective wavelength bands separated by the light separating means is arranged to be shifted.
The liquid crystal display device according to claim 1. The optical path separating means is
Having a plurality of dichroic mirrors that reflect light in any one of the wavelength bands of red, green, and blue and transmit light in other wavelength bands;
The liquid crystal display device according to claim 1. The optical path separating means is
It has a plurality of lot lenses that inject light of each separated wavelength band and make the intensity distribution uniform,
The liquid crystal display device according to claim 1. Each of the plurality of lot lenses has a different length.
The liquid crystal display device according to claim 8. The light source unit is
A discharge lamp light source, and an elliptical mirror disposed on the back side of the discharge lamp light source,
The liquid crystal display device according to claim 1. The optical axes of the light of each wavelength band separated by the light separation means are inclined with respect to each other,
The liquid crystal display device according to claim 1. The optical axes of the light in each wavelength band separated by the light separating means are inclined with respect to each other,
The lot lens has a trapezoidal cross-sectional shape,
The liquid crystal display device according to claim 8. The liquid crystal panel and the wrench killer lens are integrally formed.
The liquid crystal display device according to claim 1.

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