KR0166144B1 - Illumination device and liquid crystal display device using it - Google Patents

Abstract

In the illuminating device, the light is irradiated from the emitting tube to the light guide, and the light emitted from the light emitting surface of the light guide is focused toward the normal direction by a triangular prism of the light collecting control plate. The clock control panel makes the clock from the viewing angle within the predetermined range transparent in the normal direction, and makes the clock from the viewing angle outside the predetermined range opaque. Accordingly, the surface brightness of the lighting device can be improved, and deterioration of the display quality can be prevented, so that a high quality lighting device with high brightness can be provided.

Description

Lighting device and liquid crystal display device using the same

1 is a cross-sectional view of a lighting apparatus of an embodiment of the present invention.

2 is a perspective view of the lighting device.

3 is a cross-sectional view of a light collecting control panel provided in the lighting apparatus of FIG.

4 is a graph showing one example of luminance characteristics of the light collecting control panel.

5 is a schematic cross-sectional view of a clock control panel provided in the lighting apparatus of FIG.

6 is a graph showing one example of light transmission characteristics of the clock control panel.

7 is a cross-sectional view showing a conventional lighting device.

8 is a cross-sectional view showing a conventional lighting device.

* Explanation of symbols for main parts of the drawings

1: emitting tube 2: reflecting member

3: light guide 4: transparent resin plate

5: irregular reflector 6: reflector

7: light diffusion resin sheet 8: condensing control panel

9: clock control panel 10: liquid crystal display panel

The present invention relates to, for example, an illumination device used to illuminate the liquid crystal display from the back and a liquid crystal display device using the same as a backlight.

In general, a planar lighting device employing an edge-light system is, for example, a thin tubular discharge tube 51 which functions as a linear light source as shown in FIG. An emission tube reflecting member 52 disposed on the emission tube 51 and a light-guiding body 53 for converting linear light rays into planar light rays are provided to reflect the emitted light efficiently.

The light guide 53 has a transparent resin plate 54 excellent in light transmittance made of, for example, an acrylic resin. An irregular reflector 55 having a minute dot-shaped irregular reflector 55a formed by a method such as screen printing is formed on the lower surface of the transparent resin plate 54. Also on the irregular reflecting plate 55 is a reflecting plate 56 made of a white polyester film. Thus, the reflective surface of the surface light source is formed on the transparent resin plate 54.

On the upper surface side of the transparent resin plate 54 is a light diffusion resin sheet 57 that uniformly diffuses the light reflected by the reflecting plate 56 and transmitted through the transparent resin plate 54 toward the upper side. Thereby, the light guide 53 which converts the linear light ray from the emission tube 51 into a planar light ray is formed.

A light condensing control panel having an area substantially the same as that of the light guide body 53 in order to improve luminance in the normal direction of the top surface of the light guide body 53, that is, the top surface side of the light diffusion resin sheet 57. 58 is placed.

As an example of the condensing control panel 58, there is a restricting plate made of, for example, a sawtooth-shaped transparent plate having a lighting device disclosed in Japanese Patent Laid-Open No. 90-257188.

The condensing control panel 58 has a structure in which a plurality of triangular prisms (hereinafter referred to as triangular prisms) having vertices facing in the normal direction with respect to the surface of the condensing control panel 58 are arranged on the surface thereof as shown in FIG. The surface luminance in the normal direction is improved by using the optical refraction characteristics of these triangular prisms.

However, the vertices of the triangular prism of the condensing control panel 58 are provided so as to face the outer side of the light emitting surface of the light guide 53 as shown in FIG. 7: when the illuminating device is handled, 58) easily breaks. As a result, the light condensing performance of the light condensing control plate 58 is lowered, resulting in a decrease in luminance. In addition, since the handling of the lighting device must be carefully, there is a problem in that it takes a long time to transport or transport the lighting device and causes a decrease in the productivity of the lighting device.

In addition, due to reflection by the ridges of the triangular prisms, the surface of the condensing control panel 58 becomes a mirror state, and as a result, defects such as nonuniformity and contamination of the condensing control panel 58 itself, scratches of the triangular prism, and the like become more visible. There arises a problem that causes the display quality of the lighting apparatus to fall outside the viewing angle.

In order to solve this problem, Japanese Patent Application Laid-Open No. 93-47923 shows a light diffusion resin sheet 59 having an area substantially the same as that of the condensing control panel 58 on the upper surface side of the condensing control panel 58, as shown in FIG. The surface light source device of the structure which laminated | stacked was disclosed. In the surface light source device, the light condensing control panel 58 can be protected by the light diffusion resin sheet 59, so that the light condensing control panel 58 can be prevented from being damaged or contaminated. In addition, the light diffusion resin sheet 59 can diffuse the light from the light collecting control panel 58 to prevent irregularities or contamination of the light collecting control panel 58 itself, scratches of the triangular prism, and so on. Improve display quality.

However, as described above, the light diffusion resin sheet 59 is installed on the upper surface side of the light converging control panel 58, and the planar light rays from the light guide member 53 condensed by the light condensing control panel 58 are light diffusing resin sheet 59. Diffuses again, resulting in a decrease in surface brightness.

An object of the present invention is to provide a lighting device that improves the display quality when observed outside the viewing angle without damaging the surface brightness, another object is to use a lighting device such as the thin, low power consumption, high brightness, high quality liquid crystal display To provide a device.

In order to achieve the above object, the lighting apparatus according to the present invention is provided with a plate-shaped light guide having a light transmittance, a linear light source disposed on at least one end surface of the light guide, on the light emitting surface side of the light guide, and on the surface thereof. A plurality of prisms are formed to make the light collecting plate which transmits the light irradiated from the light emitting surface of the light guide in the normal direction of the light emitting surface and the clock within a predetermined angle, and to make the clock outside the predetermined angle with respect to the normal direction opaque It characterized in that it comprises a clock control member to make.

In this manner, the light collecting plate condenses the light irradiated from the light emitting surface of the light guide body in the normal direction, thereby improving the surface luminance in the normal direction. In addition, the clock control member makes the visual-range from the viewing angle within a predetermined angle transparent to the normal direction, while making the opacity from the viewing angle exceeding the predetermined angle with respect to the normal direction opaque, thereby providing excellent directivity. The device is realized. Therefore, by using this illuminating device as a backlight of the liquid crystal display panel, the brightness of the liquid crystal display panel can be improved when viewed from the front direction, and defects such as contamination or scratches on the liquid crystal display panel are not recognized, resulting in deterioration of the display quality. Can be prevented.

In addition, by using such an illuminating device as a backlight of the liquid crystal display panel, the liquid crystal display panel can be illuminated uniformly and brightly, and a liquid crystal display device having high brightness and good display quality can be realized.

Further, the structure of the clock control member made of a thin film-like resin sheet having the same area as that of the light converging control panel can improve the surface luminance without increasing the thickness of the lighting device and at the same time prevent deterioration of the display quality. . That is, when such an illuminating device is used as a backlight of the liquid crystal display panel, a thin, high brightness, high quality liquid crystal display device can be realized.

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

The lighting apparatus according to the present invention is a planar lighting apparatus employing an edge light method as shown in FIG. 2, and efficiently reflects the light emitted from the light emitting tube 1 and the light emitting tube 1, which is a linear light source. The reflective member 2 disposed on the emitting tube 1 and the linear light (linear ray) emitted from the emitting tube 1 and reflected by the reflecting member 2 are planar light (plane ray). It is composed of a light guide (3) that is converted into a) and emits.

Such an illuminating device is disposed on the lower surface side of the liquid crystal display panel 10 as shown in FIG. 1 and used as a backlight of the liquid crystal display device which irradiates light from the rear side of the liquid crystal display panel 10. do.

As shown in FIG. 1, in the above lighting apparatus, the light guide 3 has a transparent resin plate 4 having good light transmittance made of, for example, an acrylic resin. This transparent resin plate 4 is disposed such that one end face 4a is close to the discharge pipe 1. On the lower surface of the transparent resin plate 4, an irregular reflecting plate 5 having a micro-point irregular reflecting member 5a formed by a method such as screen printing is formed, and on the irregular reflecting plate 5, a white polyester film or the like is formed. The reflecting plate 6 which consists of these is placed. In this manner, the irregular reflecting plate 5 and the reflecting plate 6 constitute a reflecting member in the planar light source.

On the other hand, on the upper side of the transparent resin plate 4, a light diffusion resin sheet 7 for uniformly diffusing the light reflected from the reflecting plate 6 and passing through the transparent resin plate 4 toward the upper side is laminated. It is. Thus, the light guide 3 which converts linear light rays into surface light rays is comprised by the transparent resin board 4, the irregular reflecting plate 5, the reflecting plate 6, the light-diffusion resin sheet 7, etc.

In addition, on the upper surface side of the light diffusion resin sheet 7, a light condensing control plate 8 made of a transparent resin having an area substantially the same as that of the light guide 3 is laminated. The condensing control panel 8 has a surface 8a on which a plurality of triangular prisms (hereinafter referred to as triangular prisms) having a right angle of 90 ° to 100 ° as shown in FIG. 3 are formed. This triangular prism is arranged to have its apex angle in the normal direction of the condensing surface of the condensing control panel 8. Therefore, the condensing range of the planar light beam irradiated from the back side is approximately the same angle (90 ° to 100 °) as the right angle of the triangular prism, which condenses and emits the light emitted from the light diffusion sheet 7 The luminance of the light guide 3 in the normal direction is improved.

4 shows a comparison of the luminance characteristics of the illuminating device when the light condensing control panel 8 is stacked and the illuminating device when the light condensing control panel 8 is not laminated.

As shown in FIG. 4, if the luminance near the viewing angle of 0 ° when the condensing control panel 8 is not provided is set to 100%, the relative luminance ratio near the viewing angle of 0 ° is almost obtained when the condensing control panel 8 is provided. 140%, when the viewing angle is larger than 45 degrees or when the viewing angle is smaller than -45 degrees, the relative luminance ratio becomes almost 10%. In addition, when the condensing control panel 8 is not provided, the relative luminance ratio becomes smaller as the absolute value of the viewing angle is larger than 0 °. As a result, the illuminating device provided with the condensing control panel 8 can achieve about 40% luminance improvement in the normal direction (viewing angle 0 °) than the illuminating device in which the condensing control panel 8 is not laminated.

In addition, as shown in FIG. 1, on the light collecting surface side, that is, on the upper surface side of the light collecting control plate 8, the optical resin sheet 7 and the light collecting sheet 7 having the same area as the light collecting control plate 8 with a thickness of about 1 mm. Similar to the control panel 8, a visual control panel 9 (visual-range control member) made of a flexible resin sheet is laminated. As shown in FIG. 5, the clock control panel 9 has a structure in which the blind resin sheet 12 is sandwiched between two transparent PET (polyethylene terephthalate) sheets 11.

A large number of light shielding plates 12a made of light shielding resin are provided inside the blind resin sheet 12 so as to be perpendicular to and parallel to the surface of the blind resin sheet. When the viewing angle θ from the point A on the normal B is in the range of -45 ° to 45 ° by the light shielding plate 1, the viewing angle θ is set so that the haze rate of the clock control plate 9 is 10% or less. If it is in the range smaller than -45 degrees or larger than 45 degrees, transmitted light is controlled so that the haze rate of the clock control panel 9 may be 70% or more.

In addition, the haze rate is an index indicating the transmittance of the diffused light with respect to the combat and the ray consisting of parallel and diffused light passing through the object. In other words,

Haze rate (%) = diffuse light transmittance / total light transmittance * 100

Is displayed. Therefore, the smaller the haze rate, the greater the transparency of the object.

As described above, the clock control panel 9 is formed so that the haze rate becomes small from the viewing angle θ = 0 ° from the point A on the normal line B to a predetermined angle, thereby making the field of view of the light converging control panel 8 transparent and the viewing angle transparent. When θ becomes greater than or equal to a predetermined angle, the haze rate is formed to be large, thereby making the field of view of the light converging control panel 8 opaque. Accordingly, the clock control panel 9 may control the field of view of the light collecting surface of the light collecting control panel 8.

In addition, the clock control panel 9 is formed to have a thickness of about 1 mm, but may be formed thinner than this. By forming the clock control panel 9 as thin as possible, the thickness of the lighting device can be reduced, and the thickness of the liquid crystal display device having such a lighting device can be reduced.

Here, FIG. 6 shows the light transmission characteristics of the clock control panel 9 having the above configuration. In addition, in the graph shown in the same figure, the horizontal axis shows the viewing angle (theta) from the point A on the normal line B of the clock control panel 9 shown in FIG.

As is apparent from FIG. 6, the clock control panel 9 provides a transparent area having a haze rate of 10% or less when θ is in the range of approximately -45 ° to 45 °, and the viewing angle θ is smaller than -45 °. Or, if it is in a range greater than 45 °, the haze rate is formed to provide an opaque region of 70% or more. That is, the clock control panel 9 has a light transmissive characteristic such that it has transparency in the front direction and opacity in the oblique direction. That is, the clock control panel 9 is configured to transparently control the clock from the normal direction with respect to the light emitting surface of the light guide 3 and to opaquely control the clock from the oblique direction with respect to the normal.

In addition, the range in which the clock with respect to the clock control panel 9 becomes transparent is in the angle range of -45 ° to 45 ° with respect to the normal of the clock control panel 9 as described above, and the size (90 °) of this angle range is It is set to be substantially equal to or smaller than the right angle of the triangular prism provided in the condensing control panel 8. Accordingly, the clock control panel 9 emits light condensed more effectively than the triangular prism of the light condensing control panel 8 in the normal direction, and no contamination or defects other than the clock are recognized. As a result, the surface luminance of the lighting apparatus can be improved and the display quality can be prevented from being lowered.

As described above, the light emitted from the emission tube 1 is reflected from the inner surface of the reflecting member 2 and introduced into the light guide 3 or directly from the end face 4a of the transparent resin plate 4. Is introduced into (3). The light introduced into the transparent resin plate 4 is reflected and scattered by the irregular reflector 5 and the reflector 6 to become planar light, and is uniformly diffused through the light diffusion resin sheet 7. . The diffused light becomes light condensed in the normal direction by the condensing control panel 8 laminated on the light diffusion resin sheet 7 and is irradiated to the liquid crystal display panel 10 through the clock control panel 9.

At this time, the clock control panel 9 irradiates the liquid crystal display panel 10 with almost no loss of light collected by the triangular prism from the light condensing control panel 8. In addition, since the clock control panel 9 becomes opaque to the normal line and out of the so-called clock, it is possible to prevent defects such as unevenness, contamination, scratches, etc. of the light collecting control panel 8 itself, thereby improving the display quality of the lighting device. You can do it.

In addition, since the condensing control panel 8 is protected by the clock control panel 9, scratches and contamination do not occur. Thereby, the fall of the brightness | luminance by the scratch and the contamination of the condensing control panel 8 is prevented, and the display quality of an illuminating device can be improved. Therefore, scratches, stains, and the like during handling, transportation and the like of the lighting device can be prevented, so that the handling of the lighting device can be facilitated, and as a result, the productivity of the device can be improved.

Therefore, the clock control panel 9 of the lighting device having the above-described configuration has a wider field of view than the viewing angle range of the liquid crystal display panel 10, so that the condensing range and the clock control range of the lighting device are consistent with the liquid crystal display panel 10. It is possible to provide a liquid crystal display device having good display quality while irradiating light from the light source to the liquid crystal display panel 10 efficiently.

In addition, in the present Example, the clock control board 9 which has the blind resin sheet 12 was used as a clock control member in order to control a clock. However, the clock control member is not limited thereto, and for example, a film using light refraction, scattering anisotropy, or the like may be used. In this case, the light incident in the normal direction is transmitted as it is, and the angle is greater than a predetermined angle with respect to the normal direction. The field of view is controlled so that light incident in the direction of is diffused.

Those skilled in the art will appreciate that many modifications may be made without departing from the scope and spirit of the invention. Accordingly, the appended claims should not be limited to the foregoing description but should be construed broadly.

Claims (22)

A plate-shaped light guide having a light transmittance, a linear light source disposed on at least one end surface of the light guide, and a plurality of prisms are formed on the surface of the light guide and irradiated from the light emitting surface of the light guide. A condensing control panel for condensing the transmitted light while condensing in the normal direction of the light emitting surface; and a clock control member for making a clock within a predetermined angle with respect to the normal direction and making the clock at a predetermined angle opaque with respect to the normal direction. Illumination apparatus, characterized in that. The prism of claim 1, wherein the prism installed in the light collecting plate has a triangular angle of 90 ° to 100 ° and the viewing angle of the watch control member making the clock transparent is substantially the same as the prism of the prism, but smaller than the prism. Illumination set. The illumination device according to claim 1, wherein the clock control member includes a plurality of light blocking plates orthogonal to and parallel to the surface of the light collecting plate, wherein the light blocking plate is set so that the haze rate increases rapidly when the viewing angle exceeds a predetermined value. 4. The lighting apparatus of claim 3, wherein the haze rate of the clock control member is controlled by the light shielding plate to be 10% or less in the transparent viewing angle range and 70% or more in the opaque viewing angle range. The apparatus of claim 1, wherein the clock control member is a film member having an optical characteristic for transmitting light incident at an angle within a predetermined angle with respect to a normal direction and scattering light incident at an angle greater than the predetermined angle. . The illumination device according to claim 1, wherein the clock control member is made of a thin film resin sheet covering an area substantially the same as that of the light collecting plate. The illumination control device of claim 6, wherein the clock control member is formed of a blind resin sheet sandwiched between transparent resin sheets, and the blind resin sheet includes a plurality of light shielding plates provided at right angles and parallel to each other. Device. The illuminating device according to claim 1, wherein the light guide includes an irregular reflector for scattering light provided on a rear surface of the light guide when the light emitting surface is faced. The reflector according to claim 1, further comprising a reflector provided on the back side of the light guide when reflecting the light emitting surface side of the light guide to the front, and reflecting the light emitted from the light guide toward the back side toward the inside of the light guide. Including lighting device. The lighting apparatus according to claim 1, further comprising a reflecting member for reflecting the light irradiated in a direction different from the direction of incidence from the linear light source to the light guide toward the light guide. The lighting apparatus according to claim 1, further comprising an optical scattering sheet for diffusing light between the light guide and the light collecting plate. A liquid crystal display panel, a light guide plate provided on the rear side of the liquid crystal display panel so as to be parallel to the liquid crystal display panel, a light source for injecting light into at least one end face of the light guide plate, between the light guide plate and the liquid crystal display panel; A light collecting plate that transmits the light emitted from the light guide plate while condensing in the normal direction, and is installed between the light guide plate and the liquid crystal display panel, and makes a clock within a predetermined angle with respect to the normal direction, and a clock outside a predetermined angle with respect to the normal direction. Liquid crystal display comprising a clock control member for making the opaque. The liquid crystal display device according to claim 12, wherein the range of the viewing angle at which the clock control member makes the clock transparent is set to be wider than the viewing angle range of the liquid crystal display panel. 13. The liquid crystal display device according to claim 12, wherein the light collecting plates each include a triangular prism on a surface of the liquid crystal display panel side. The liquid crystal display device according to claim 12, wherein the clock control member includes a plurality of light blocking plates perpendicular to the surface of the light collecting plate and arranged in parallel with each other, wherein the light blocking plate is set such that the haze rate increases rapidly when the viewing angle exceeds a predetermined value. Display. The liquid crystal display of claim 12, wherein the clock control member is a film member having an optical characteristic for transmitting light incident at an angle within a predetermined angle with respect to a normal direction and scattering light incident at an angle greater than the predetermined angle. Device. The liquid crystal display device according to claim 12, wherein the clock control member is made of a thin film resin sheet having an area substantially the same as that of the light collecting plate. 18. The liquid crystal display of claim 17, wherein the clock control member is formed of a blind resin sheet sandwiched between transparent resin sheets, and the blind resin sheet includes a plurality of light shielding plates disposed perpendicularly to and parallel to each other. Display. 13. The liquid crystal display of claim 12, wherein the light guide plate includes an irregular reflector for scattering light provided on one of the surfaces disposed in parallel with the liquid crystal panel, and one of the surfaces is located farther from the liquid crystal panel than the other surface. 13. The liquid crystal display device according to claim 12, further comprising a reflecting plate provided on the back side of the light guide plate when the light emitting surface side is in front, and reflecting light emitted from the light guide plate toward the inside of the light guide plate. The liquid crystal display device of claim 12, further comprising a reflecting member reflecting light irradiated in a direction different from a direction of incidence from the linear light source to the light guide plate toward the light guide plate. The liquid crystal display device of claim 12, further comprising a light diffusion sheet positioned between the light guide plate and the light collecting plate to diffuse light.