WO2007141955A1

WO2007141955A1 - Illuminator and display

Info

Publication number: WO2007141955A1
Application number: PCT/JP2007/057981
Authority: WO
Inventors: Kensei Tsuji; Hirokazu Mouri
Original assignee: Sharp Kabushiki Kaisha
Priority date: 2006-06-08
Filing date: 2007-04-11
Publication date: 2007-12-13

Abstract

Number of linear light sources can be decreased by providing large interval portions (L2, L3) where the distance between the axes of adjoining cold cathode tubes (23) is long. Since a wide light source (flat lamp (23B)) where the overall dimension (width dimension) of the cold cathode tube (23) is large in the parallel direction is used at the large interval portion, luminance distribution can be made smooth. Consequently, display quality of a liquid crystal display (10) can be enhanced.

Description

Lighting device and display device

Technical field

The present invention relates to a lighting device and a display device.

Background art

[0002] As a liquid crystal display device which is a kind of display device, one having a structure for irradiating an electronic image displayed on a liquid crystal panel with illumination light as much as an illumination device is widely used. As the lighting device, a knock light device arranged on the back side of the liquid crystal panel is often employed. In particular, a backlight device arranged directly under the back surface of the liquid crystal panel is called a direct type. In direct type backlight devices, generally, a plurality of linear light sources (cold cathode fluorescent lamps, etc.) are arranged along the liquid crystal panel surface in parallel with each other at equal intervals, and the illumination light of each linear light source is diffused by a diffusion plate, etc. The liquid crystal panel is irradiated by diffusing.

As a liquid crystal display device using such a direct type backlight device, a plurality of linear light sources 101 are arranged at non-uniform intervals on the back side of the liquid crystal panel 102 as shown in FIG. There is. In this arrangement, the linear light sources 101 adjacent to each other are arranged so that the interval between them is small at the central portion and large at the peripheral portion. This ensures the necessary brightness at the center of the device and reduces the cost by reducing the number of linear light sources 101 in the peripheral area compared to the conventional one (linear light sources arranged at equal intervals). Can be achieved.

Note that a liquid crystal display device in which linear light sources are arranged at non-uniform intervals is disclosed in, for example, Patent Document 1 below.

Patent Document 1: JP 2005-347062 A

Disclosure of the invention

[0004] (Problems to be solved by the invention)

FIG. 8 is a graph illustrating the luminance distribution of the light beam emitted from each linear light source 101 to the liquid crystal panel 102 in the above configuration. As shown in the figure, in the central part (near reference C), the linear light sources 101 are arranged at small intervals, and therefore the change in luminance is small. On the other hand, in the peripheral part, adjacent linear light sources 101 (broken lines are arranged in the peripheral part) Since the distance between the linear light sources 101 (which indicates the position of the linear light source 101) is larger than the width dimension (outer diameter) of the linear light source 101, the light cannot be sufficiently diffused by the diffusion plate 103 or the like. A so-called lamp image appears in which the space between the linear light sources 101 where the light directly above the light source 101 is bright is dark. As described above, the above configuration has a problem in that the display quality as a display device is deteriorated because the change in luminance becomes large at a place where the interval between the linear light sources 101 is large. The present invention has been completed based on the above circumstances, and an object thereof is to provide an illumination device and a display device capable of reducing the number of linear light sources and smoothing the luminance distribution. And

[0005] (Means for solving the problem)

As means for achieving the above object, the illumination device of the present invention is an illumination device in which a plurality of linear light sources are arranged in parallel, and the distance between the axes of a pair of adjacent linear light sources Are provided with a relatively large large interval portion and a small interval portion whose interval is relatively smaller than the large interval portion, and at least one of the pair of linear light sources constituting the large interval portion is: It is characterized in that it also has a wide light source force in which the outer dimension in the parallel direction is relatively larger than the pair of linear light sources constituting the small interval portion.

[0006] According to the present invention, it is possible to reduce the number of linear light sources as a whole by providing a large interval portion where the distance between the axes of adjacent linear light sources is large. In addition, since a wide light source having a large outer dimension (width dimension) in the parallel direction is used for the large interval portion, the luminance distribution can be made smooth.

[0007] In the illumination device according to the present invention, the small interval portion is disposed at a central portion in the parallel direction of the plurality of linear light sources, and the large interval portion is arranged on both sides of the central portion. It can be arranged in the periphery.

[0008] In this case, the linear light source is arranged so that the interval between the axes of the linear light sources is small in the central part and large in the peripheral part, so that sufficient luminance is secured in the central part and the entire linear light source The number of can be reduced.

[0009] In the illumination device according to the present invention, the plurality of linear light sources includes a circular light source having a circular cross section and a flat light source having a flat cross section and a major axis larger than the outer diameter of the circular light source. The flat light source serves as the wide light source and has a substantially linear light in the major axis direction. It can be arranged in a direction along the parallel direction of the sources.

[0010] In this case, the linear light source is composed of a circular light source and a flat light source, the flat light source is a wide light source, and the major axis direction is arranged in the direction along the parallel direction of the linear light sources. As a result, the thickness dimension of the apparatus can be reduced as compared with the case where the wide light source is constituted by a circular light source having a large outer diameter.

[0011] In the illumination device according to the present invention, each of the plurality of linear light sources has a circular cross section, and the wide light source has an outer diameter that is larger than that of the pair of linear light sources forming the small interval portion. Can be large.

[0012] In this case, by using all the linear light sources as circular light sources, the configuration can be made cheaper than when a flat light source or the like is used.

[0013] In the illumination device according to the present invention, a ratio between the maximum interval and the minimum interval (maximum interval Z minimum interval) is 1.5 or less in the interval between the axes of the pair of adjacent linear light sources. It can be done.

[0014] In this case, if the ratio between the maximum interval and the minimum interval is larger than 1.5, the difference in brightness and darkness is clearly visible on the display screen, which is not preferable in terms of display quality. By setting the ratio to 1.5 or less, the difference in light and darkness on the display screen can be suppressed to a level where there is no practical problem.

Next, the display device of the present invention irradiates the display unit with the illumination device according to the present invention, a display unit for displaying an image, and the illumination light from the illumination device diffused. And a diffusing member.

Brief Description of Drawings

FIG. 1 is an exploded perspective view of a liquid crystal display device according to Embodiment 1 of the present invention.

[Figure 2] Cross section of liquid crystal display

[Figure 3] Plan view of the knocklight device with the frame and optical sheet removed

[Figure 4] Graph showing luminance distribution

FIG. 5 is a cross-sectional view of a liquid crystal display device according to Embodiment 2 of the present invention.

FIG. 6 is a sectional view of a liquid crystal display device according to another embodiment.

[Fig. 7] Cross-sectional view of a conventional liquid crystal display device

FIG. 8 is a graph showing the luminance distribution of a conventional liquid crystal display device Explanation of symbols

[0017] 10 ... Liquid crystal display device (display device), 11 ... Liquid crystal panel (display unit), 12 ... Backlight device (lighting device), 21 ... Base (diffusion member), 22. .. Optical sheet (diffuse member), 23 ... Cold cathode tube (linear light source), 23A ... Circular lamp (circular light source), 23B ... Flat lamp (wide light source, flat light source), 23C ... Circular lamp (wide light source, circular light source)

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 of the present invention will be described with reference to FIGS. Embodiment 1 shows a liquid crystal display device 10 which is an example of a display device. In the following explanation, Fig. 2 is used as a reference for the upward and downward directions.

As shown in FIG. 1, the liquid crystal display device 10 is roughly divided into a liquid crystal panel 11 (corresponding to the “display section” of the present invention) that has translucency and displays an image and the like, and the back side thereof. A backlight device 12 (corresponding to the “illumination device” of the present invention) disposed on the (back side) and a substantially frame-shaped bezel 13 for holding the liquid crystal panel 11 are provided. The liquid crystal panel 11 is received by the frame 14 of the knocklight device 12 and the bezel 13 is fixed to the frame 14 with the front side force by screws B (see FIG. 2). Is held between the two.

As shown in FIG. 2, the liquid crystal panel 11 includes a pair of glass substrates 15 having a rectangular flat plate shape, a liquid crystal 16 filled between the glass substrates 15, and outer surfaces of the glass substrates 15 (liquid crystals A pair of polarizing plates 17 attached to the surface opposite to the 16 side). Both glass substrates 15 are bonded to each other with a predetermined gap therebetween by a spacer. The glass substrate 15 on the knocklight device 12 side has switching elements (for example, TFTs) connected to the source wiring and the gate wiring orthogonal to each other, and the glass substrate 15 on the display surface side has R, G, B The colored portions are provided in a matrix. At the end of the glass substrate 15 on the backlight device 12 side, as shown in FIG. 1, one end of SOF19 (System On Film) is passed through an anisotropic conductive film (ACF) with respect to the source wiring and gate wiring. The printed circuit board 20 is connected to the other end of the SOF 19. This printed circuit board 20 is bent with respect to the frame 14 in a vertical posture while bending the SOF 19. It is fixed by the

As shown in FIG. 2, the knock light device 12 is configured to cover a rectangular metal base 21 having an opening on the upper surface side (liquid crystal panel side) and an opening of the base 21. A plurality of optical sheets 22 to be attached, a rectangular frame 14 that can be held in a state where these optical sheets 22 are sandwiched between the bases 21, and a plurality of linear light sources accommodated in the base 21 ( Eight cold cathode tubes 23 in FIG. 3 are provided.

[0022] The inner surface of the base 21 is painted white, and reflects and diffuses the irradiation light from each cold cathode tube 23. In addition, each optical sheet 22 is formed by laminating four sheets, a diffusion plate, a diffusion sheet, a lens sheet, and a brightness enhancement sheet, from the bottom to the top. However, the base 21 and the optical sheets 22 correspond to the “diffusion member” of the present invention.

[0023] The cold cathode tube 23 is a kind of discharge tube, and is provided with electrodes at both ends of an elongated cylindrical glass tube in which mercury is enclosed, and electrons emitted from the electrode cage collide with mercury. As a result, ultraviolet rays are emitted from the excited mercury, and the ultraviolet rays become visible light by the phosphors coated on the inner surface of the glass tube, thereby emitting light.

[0024] The cold cathode tube 23 includes a circular lamp 23A (corresponding to the "circular light source" of the present invention) having a circular cross section (substantially perfect circle) and a flat lamp 23B having a flat cross section elongated in one direction ( It corresponds to the “wide light source” and “flat light source” of the present invention). The cross-sectional shape of the flat lamp 23B is such that its major axis is larger than the outer diameter of the circular lamp 23A and its minor axis is slightly smaller than the outer diameter of the circular lamp 23A. As shown in FIG. 3, the circular lamp 23A and the flat lamp 23B have their axes (center axis along the longitudinal direction) parallel to the longitudinal direction of the base 21 (liquid crystal panel 11) and the base 21 (liquid crystal They are arranged parallel to each other along the short direction of panel 11). Four circular lamps 23A are arranged in the central part in the parallel direction of the cold cathode tubes 23, and four flat lamps 23B are arranged in two peripheral parts on both sides across the central part. Yes. The flat lamps 23B are arranged in such a direction that the major axis direction is along the parallel direction.

[0025] In the central portion of the cold cathode tubes 23 in the parallel direction, the circular lamps 23A have a constant interval L1 (small interval portion) between the axes, and are positioned at both ends of the four circular lamps 23A. The distance between the circular lamp 23A and the adjacent flat lamp 23B is L2 (large interval portion) larger than LI, and the distance between the axes of the flat lamp 23B and the adjacent flat lamp 23B is larger than L2. , L3 (Large Interval) !! (ie LI <L2 L3).

In addition, in the distance between the axes of a pair of adjacent cold-cathode tubes 23, the ratio of the maximum distance (L3) to the minimum distance (L1) is set to 1.5 or less ((L3ZL1) <1.5) ).

[0026] The present embodiment has the above-described structure, and the operation thereof will be described next.

FIG. 4 is a graph showing an example of the luminance distribution of light rays radiated from each cold cathode tube 23 to the liquid crystal panel 11. In the figure, the position of symbol C indicates the center position of the cold cathode tubes 23 in the parallel direction, and the broken line indicates the position of the axis of each flat lamp 23B.

[0027] As shown by the solid line in the figure, since the cold cathode tubes 23 are densely arranged in the central portion (near the center C) in the parallel direction of the cold cathode tubes 23, the luminance is relatively high and substantially constant. is there. On the other hand, in the peripheral portion, the luminance decreases as the central force also increases. Further, in the peripheral portion, the force between the cold cathode tubes 23 is increased. The cold cathode tubes 23 constituting the large interval portions (L2, L3) having a large interval are at least one flat lamp 23B having a wide width. Therefore, in the peripheral portion, the light source is provided to a position closer to the inner side than in the case where the circular lamp 23A is used as in the prior art. For this reason, in this embodiment (see the solid line), compared to the conventional case (see the two-dot chain line), the drop in luminance between the cold cathode tubes 23 (near the center of the large interval) is reduced, and the luminance distribution changes gently. .

[0028] As described above, according to the present embodiment, by providing the large interval portions L2, L3 where the distance between the axes of the adjacent cold cathode tubes 23 is large, the number of the entire linear light sources can be reduced. it can. Further, since a wide light source (flat lamp 23B) having a large outer dimension (width dimension) in the parallel direction of the cold cathode tubes 23 is used in the large interval portion, the luminance distribution can be made smooth. Thereby, the display quality of the liquid crystal display device 10 can be improved.

[0029] In addition, the spacing force of the axis of the cold cathode tube 23 is arranged so as to increase in the peripheral portion which is small in the central portion, so that sufficient luminance is ensured in the central portion and the entire cold cathode tube is provided. The number of 23 can be reduced.

[0030] On the irradiation surface of the illuminating device, a region where the lamp interval is wide generally has a low luminance. The luminance is high in the region where the gap is narrow. When this illumination device is used for a display device, dark portions and bright portions are generated in the screen, which is not preferable in terms of display quality. However, when the display quality of various lamps was observed, the ratio between the maximum value and the minimum value of the lamp interval was set to 1.5 or less, so that the difference between the bright and dark areas was suppressed to an invisible level. I was able to.

[0031] The cold cathode tube 23 also constitutes a force with the circular lamp 23A and the flat lamp 23B, the flat lamp 23B is a wide light source, and the major axis direction is arranged in the direction along the parallel direction of the cold cathode tubes 23. As a result, the thickness of the apparatus can be reduced as compared with the case where the wide light source is formed of a circular light source having a large outer diameter.

Embodiment 2 of the present invention will be described with reference to FIG. In the second embodiment, the configuration content of the cold cathode tube 23 is different from that in the first embodiment. Since the other configuration is the same as that of the first embodiment, the same structure as that of the first embodiment is denoted by the same reference numeral and description thereof is omitted.

[0033] The cold-cathode tube 23 includes a circular lamp 23A similar to that of the first embodiment and a circular lamp 23C having a larger outer diameter than that of the circular circular lamp 23C ("wide light source" and " Equivalent to a “round light source”). Four circular lamps 23A are arranged in the center as in the first embodiment, and the circular lamp 23C having a large diameter is a wide light source and has the same position as the flat lamp 23B in the first embodiment (position of the axis) as a wide light source. Are four).

[0034] Also in the present embodiment, by using a wide light source (circular lamp 23C) at a location where the distance between the axes of adjacent cold-cathode tubes 23 is large (large spacing portions L2, L3), the luminance distribution is obtained. It can be made gentle. Thereby, the display quality of the liquid crystal display device 10 can be improved.

[0035] Further, by forming all the cold cathode tubes 23 with the circular lamps 23A, 23C, it is possible to make the structure cheaper than when the flat lamp 23B or the like is used.

The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

(1) In the above embodiment, the power described in the case of 8 lamps is the number of lamps depending on the area of the irradiation surface of the illumination device, the display area of the display device, and the required screen brightness. It will be changed accordingly. For example, if the screen size is 46 type (diagonal dimension of the display area is 46 inches), 18 to 22 lines, if the screen size is 65 type (diagonal dimension of the display area is 65 inches), 2 4 to 34 lines, etc. be able to. Further, the ratio of using a wide linear light source in the entire linear light source is not limited to the above example. As for the width of the light source, lamps with three or more widths may be arranged as shown in the above example with two types (in this case, a wide lamp with a large distance between a pair of adjacent lamps). Is desirable for smoothing the luminance distribution). In addition, for example, a circular lamp 23A is a lamp with an outer diameter of 4 mm, and a flat lamp 23B is a substantially elliptical shape in which a circular lamp with an outer diameter of 4 mm is crushed in one direction so that the minor axis is about 60% of the major axis. A shaped lamp can be used.

[0037] (2) In the above-described embodiment, the arrangement of the force-line light sources showing the arrangement in which the small interval portion is arranged in the central portion and the large interval portion is arranged in the peripheral portion can be appropriately changed. For example, as shown in FIG. 6, a large interval portion may be arranged in the center and a small interval portion may be arranged in the periphery. Here, a circular lamp 23A is arranged in the periphery, and a flat lamp is arranged in the center. A wide light source such as 23B is arranged. Further, for example, the large interval portions and the small interval portions may be alternately arranged.

[0038] (3) If desired, in order to obtain a luminance distribution, the luminance may be adjusted appropriately using a reflector, a light guide plate, or the like. When a flat light source is used, the luminance distribution may be adjusted by arranging the major axis direction so as to form a predetermined angle with respect to the parallel direction. Furthermore, the luminance distribution may be adjusted by changing the magnitude of the current supplied to each linear light source.

(4) In the embodiment described above, the distance to the display unit may be different depending on the force line light source arranged such that the axis of each linear light source is aligned in parallel with the liquid crystal panel (display unit).

(5) In the above-described embodiment, an example in which a cold cathode tube is used as the linear light source is illustrated. However, in addition to the cold cathode tube, a discharge tube such as a hot cathode tube or a xenon tube can also be used.

Claims

The scope of the claims

[1] A lighting device in which a plurality of linear light sources are arranged in parallel,

A large interval portion in which the distance between the axes of a pair of adjacent linear light sources is relatively large and a small interval portion in which the interval is relatively smaller than the large interval portion are provided to constitute the large interval portion. At least one of the pair of linear light sources has a wide light source power whose outer dimension in the parallel direction is relatively larger than that of the pair of linear light sources constituting the small interval portion. .

[2] The small interval portion is disposed in a central portion in the parallel direction of the plurality of linear light sources, and the large interval portion is disposed in peripheral portions on both sides across the central portion. The lighting device according to claim 1.

[3] The plurality of linear light sources includes a circular light source having a circular cross section and a flat light source having a flat cross section and a major axis larger than the outer diameter of the circular light source. 3. The illumination device according to claim 1, wherein the light source is arranged in a direction in which a major axis direction thereof is substantially along a parallel direction of the linear light sources.

[4] The plurality of linear light sources each have a circular cross section, and the wide light source has an outer diameter larger than that of the pair of linear light sources constituting the small interval portion. The lighting device according to claim 1 or claim 2.

[5] In the interval between the axes of the pair of adjacent linear light sources, the ratio of the maximum interval to the minimum interval (maximum interval Z minimum interval) is 1.5 or less. Term

The lighting device according to claim 1, wherein V is a deviation.

[6] The lighting device according to any one of claims 1 to 5, and a display unit that displays an image,

A diffusing member that irradiates the display unit side in a state in which illumination light from the illuminating device is diffused;

A display device comprising: