Source: https://patents.google.com/patent/JP4255302B2/en
Timestamp: 2020-06-06 08:05:41
Document Index: 385129770

Matched Legal Cases: ['art 2', 'art 2', 'art 2', 'Application No. 2002', 'art\n2', 'art\n2', 'art\n4']

JP4255302B2 - Liquid crystal display lighting device and liquid crystal display device - Google Patents
Liquid crystal display lighting device and liquid crystal display device Download PDF
JP4255302B2
JP4255302B2 JP2003097360A JP2003097360A JP4255302B2 JP 4255302 B2 JP4255302 B2 JP 4255302B2 JP 2003097360 A JP2003097360 A JP 2003097360A JP 2003097360 A JP2003097360 A JP 2003097360A JP 4255302 B2 JP4255302 B2 JP 4255302B2
JP2003097360A
JP2004303657A (en
2003-03-31 Priority to JP2003097360A priority Critical patent/JP4255302B2/en
2004-10-28 Publication of JP2004303657A publication Critical patent/JP2004303657A/en
2009-04-15 Publication of JP4255302B2 publication Critical patent/JP4255302B2/en
239000004973 liquid crystal related substances Substances 0.000 title claims description 209
238000005286 illumination Methods 0.000 claims description 62
238000000149 argon plasma sintering Methods 0.000 claims description 52
238000005429 turbidity Methods 0.000 claims description 41
239000011347 resins Substances 0.000 description 52
The present invention relates to a liquid crystal display illumination device and a liquid crystal display device in which, for example, a transmissive liquid crystal panel or a transmissive liquid crystal panel with a reflection function is disposed on the liquid crystal display illumination device, and in particular, an effective display area of the liquid crystal panel. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display illumination device having a very narrow frame in which a linear light source is disposed and a liquid crystal display device using the same.
In this type of liquid crystal display device, narrowing of the frame is one of the technical development requirements. This narrowing of the frame is intended to make the frame area outside the effective display area of the liquid crystal panel as narrow as possible. In order to answer this narrowing of the frame, the present inventors have developed a narrowing frame technology that can be mass-produced through repeated research to realize a narrow frame of the liquid crystal display device, and proposed this as Patent Document 1. . For example, a liquid crystal display device for car navigation in which a liquid crystal panel is arranged on a liquid crystal display illumination device has been commercialized. Such a liquid crystal display device of Patent Document 1 will be described in detail with reference to FIG.
FIG. 6 is a cross-sectional view showing one end of a conventional liquid crystal display device.
In FIG. 6, the liquid crystal display device 200 has a liquid crystal panel 20 disposed on a lighting device 10. The illumination device 10 includes a circular fluorescent tube 1, a light scattering resin portion 2, a reflection plate 3, a light guide 4, and diffusion sheets 5 to 7. These are accommodated in a concave back casing 31 made of metal.
The circular fluorescent tube 1 is a linear light source that irradiates light to the light incident end surface 4 c of the light guide 4. The fluorescent tube 1 is disposed at a position surrounded by the light incident end face 4 c of the light guide 4 and the light scattering resin portion 2.
The light-scattering resin part 2 has portions with different thicknesses in a stepped manner.
The reflection plate 3 has a function of reflecting light returned from the light guide 4 back to the light guide 4 side.
The light guide 4 propagates the light incident from the one end face 4c inside, and uniformly emits the light from the upper face 4a on the one surface to the liquid crystal panel 20 side. The light guide 4 has a thin plate portion 4d of a translucent resin portion in a state where the upper surface 4a side protrudes outward with a predetermined thickness, and the thickness of the light scattering resin portion 2 is the thickness of the thin plate portion 4d. It is received from below in a thin part. An end portion (end surface b of the thin plate portion 4d) between the thin portion of the light scattering resin portion 2 and the thin plate portion 4d is set at the same position as the boundary surface a of the effective display area A of the liquid crystal panel 20. ing.
The lower diffusion sheet 5 / prism sheet 6 / upper diffusion sheet 7 performs an optical process such as diffusing the light emitted from the light guide 4. In the liquid crystal display device 200, in the front view direction, the degree of scattering ability of the light scattering resin portion 2 is optimized, and the diffusion sheet disposed on the light scattering resin portion 2 and the light guide 4. By optimizing the combination of 5 to 7, a certain level of display quality can be realized.
Another example of the narrowing frame technology is a liquid crystal display device disclosed in Patent Document 2. Such a liquid crystal display device of Patent Document 2 will be described in detail with reference to FIG.
FIG. 7 is a cross-sectional view showing one end of another conventional liquid crystal display device. In addition, the same code | symbol is attached | subjected to the member which show | plays the effect similar to the structural member of FIG.
7, in the liquid crystal display device 300, the liquid crystal panel 20 is disposed on the illumination device 10A, as in the case of FIG. This illuminating device 10A includes a circular fluorescent tube 1, a reflector 3, a light guide 4A, and diffusion sheets 5 and 7, and in particular, compared with the liquid crystal display device 200 of FIG. 6, the light guide 4A. The configuration is different.
The light guide 4A propagates light incident from an inverted L-shaped light incident end surface composed of a thin plate portion 4d projecting from the upper surface 4a side of the end surface 4c and the end surface 4c to allow the upper surface 4a on one surface to propagate inside. To emit light. The circular fluorescent tube 1 is arranged in a range surrounded by an inverted L-shaped light incident end face and the reflection plate 3.
The light guide 4A is provided with a prism surface 40a inclined at an angle of 30 ° to 60 ° with respect to the light emitting surface on the surface 40 on the thin plate portion 4d, and this prism surface 40a provides a circular fluorescent tube. The light from 1 is reflected in the central direction (arrow direction) of the light guide 4. Thereby, it is possible to suppress an increase in the amount of light emitted from the surface 40 on the thin plate portion 4d of the light guide plate 4A and to increase the uniformity of the light emitting surface.
The liquid crystal display device 300 disclosed in Patent Document 2 is excellent in that the cost can be reduced because the light guide 4A can be made of a single material.
JP 2000-235805 A
JP-A-11-72626
However, although the liquid crystal display device 200 of Patent Document 1 described above can achieve a certain level of display quality in the front view direction, the light scattering resin portion 2 and the thin plate portion of the transparent resin portion when observed from an oblique direction. The outer end of the overlapping portion with 4d (end surface b of thin plate portion 4d; boundary surface) is visually observed. At this boundary surface, since the overlapping ratio in the thickness direction of the light scattering resin portion 2 and the thin plate portion 4d of the transparent resin portion changes, the transmittance is extremely reduced outside the boundary surface compared to the inside of the boundary surface. As a result, the luminance becomes discontinuous and a color change appears in the vicinity due to the difference in the transmission spectrum. As a result, there is a problem that the market of products using the liquid crystal display device 200 and the demands of customers cannot be fully satisfied.
Further, there is a demand for a liquid crystal display device with a narrower frame, and it is strongly necessary to make compatible such conflicting technologies of the narrower frame portion with the uniformity of the light emitting surface and the luminance continuity at an oblique viewing angle. It has been demanded.
Further, in the liquid crystal display device 300 of Patent Document 2, although the number of parts is small in that the light guide 4A is made of one kind of material, the processability such as the processing of the prism surface is poor. From the beginning of the research, we are studying technical solutions by combining two types of optical materials. For this reason, the present invention and Patent Document 2 have different technical directions for solving the problems, and their technical ideas are completely different.
The present invention solves the above-mentioned conventional problems, and can achieve ultra-narrow frame, uniformity of light emitting surface / display surface and luminance continuity in oblique viewing angle, and can achieve high-dimensional photoelectric characteristics. An object of the present invention is to provide a liquid crystal display illumination device that can be held and a liquid crystal display device using the same.
The illuminating device for liquid crystal display of the present invention is provided with a thin plate portion projecting from the end surface on the surface side, a light guide that propagates light incident from the end surface inside and emits it from the surface, and a step portion. The light scattering plate member is configured to have different thicknesses, and is disposed so that the thin plate portion overlaps the surface of the thin side, and is provided near the back surface and the end surface of the light scattering plate member, The back surface of the light scattering plate member and The A linear light source that irradiates light to the end face, and the end face position of the thin plate portion is provided outside the effective display area of the liquid crystal panel. The linear light source is a fluorescent tube having at least one side portion having one or more bent portions and processed into an elliptical cross section, and the at least one side portion is the linear light source for the light scattering plate member. The light emission surface of the linear light source with respect to the end surface of the light guide is configured to be wider in area than the light emission surface side of This achieves the above object.
Preferably, the thin plate portion of the light guide in the illuminating device for liquid crystal display of the present invention protrudes from the end face with a surface width flush with the surface of the light guide, and the light scattering plate member is thick. The surface on the side and the surface of the thin plate portion overlap each other in a flush state.
Further preferably, the linear light source in the liquid crystal display illumination device of the present invention has an elliptical cross section.
Further preferably, the linear light source in the illumination device for liquid crystal display of the present invention is: cross section The major axis direction of the elliptical shape and the direction perpendicular to the end face of the light guide are arranged so as to be substantially perpendicular.
Further preferably, in the liquid crystal display lighting device of the present invention, one side portion processed into an elliptical cross section is provided on the high voltage side.
Further preferably, the linear light source in the illuminating device for liquid crystal display of the present invention has an elliptical cross-section processed portion in a portion other than the electrode portion.
Further preferably, in the liquid crystal display lighting device of the present invention. cross section The minor axis / major axis ratio of the elliptical shape is 0.6 or more and less than 1.0.
Further preferably, in the liquid crystal display lighting device of the present invention. cross section The photoelectric characteristics of the elliptical fluorescent tube show that the rate of increase of the lighting start voltage exceeds 0% and within 15%, and the rate of increase of the drive voltage exceeds 0% and within 10%, compared to that before the ellipse processing. The rate of change in luminance is within ± 15%.
Further preferably, the end face on the light guide side of the light scattering plate member in the illumination device for liquid crystal display of the present invention is provided on the inner side of the end face of the light guide.
Further preferably, an optical sheet in which a low turbidity diffusion sheet and a high turbidity diffusion sheet are combined is provided on the surface of the light guide in the liquid crystal display lighting device of the present invention.
Further preferably, an optical sheet in which a polarization selective reflection sheet and a high turbidity diffusion sheet are combined is provided on the surface of the light guide in the liquid crystal display illumination device of the present invention.
Furthermore, preferably, by providing a reflective sheet on the back side of the light guide in the liquid crystal display lighting device of the present invention and providing a fixing auxiliary material on the back side of the reflective sheet at the lower end of the light guide. The surface of the reflection sheet and the back surface of the light guide are in contact with each other at the lower end of the light guide.
A liquid crystal display device of the present invention is a liquid crystal display illumination device according to any one of claims 1 to 14 and a light transmission device disposed on the liquid crystal display illumination device and transmitting light emitted from the liquid crystal display illumination device. And a transmissive liquid crystal panel that displays by non-transmission, thereby achieving the above object.
The liquid crystal display device of the present invention is disposed on the liquid crystal display illumination device according to any one of claims 1 to 14 and the liquid crystal display illumination device, and is irradiated with light from the liquid crystal display illumination device. A transmissive liquid crystal panel with a reflective function is provided, which performs display by transmission and non-transmission, and also performs display by reflection of light from the outside, thereby achieving the above object.
In the present invention, the outer end (boundary surface; end face of the thin plate portion) of the overlapping portion of, for example, the light transmitting resin portion of the light guide thin plate portion and the light scattering resin portion of the light scattering plate member is the liquid crystal panel. Since it is set outside the effective display area, it is possible to further ensure luminance continuity on the light emitting surface as compared with the illumination device disclosed in Patent Document 1, and a liquid crystal panel on the illumination device. When the is installed, the outer edge (boundary surface) of the overlap between the translucent resin part and the light-scattering resin part can be prevented from being seen not only from the front view but also from an oblique direction. The display quality can be ensured by the simple display.
In addition, by using a linear light source having an elliptical cross section, for example, an elliptical fluorescent tube, the dimension of the thin plate portion of the light guide is shortened in the longitudinal direction as compared with the case where a circular fluorescent tube is used. Therefore, it is possible to realize a liquid crystal display lighting device with a very narrow frame. In addition, by arranging the long axis direction of the elliptical fluorescent tube so as to be substantially perpendicular to the direction perpendicular to the light incident surface, the tube surface luminance in the long axis direction is lower than that of the circular fluorescent tube. Therefore, it becomes possible to suppress the luminance change around the frame portion of the lighting device. Furthermore, since the tube surface luminance in the short axis direction is higher than that of the circular fluorescent tube, the amount of light incident on the light guide is increased and the luminance can be improved as a whole. Accordingly, it is possible to realize a liquid crystal display lighting device with a very narrow frame that is strongly demanded by the product market and customers, and at the same time, maintain the photoelectric characteristics of the conventional liquid crystal display lighting device and achieve high brightness. It is possible to realize a simple lighting device.
Further, by arranging a fixing auxiliary material used for fixing the lighting device to the housing, for example, at the lower part of the incident end surface, the gap between the lower surface of the light guide near the incident end surface and the reflection sheet is made smaller or abutted. Therefore, the amount of light incident on the gap can be greatly reduced or eliminated. This suppresses or prevents the unnecessary reflection of stray light incident between the light guide entrance end surface and the reflective sheet, and reduces abnormal brightness variations and brightness changes near the light guide entrance end surface. Or it becomes possible to prevent. Therefore, by disposing the fixed auxiliary material in this positional relationship, it becomes possible to obtain a liquid crystal display device with better display quality than before.
Also, in fluorescent tubes such as U-shaped tube type, L-shaped tube type and B-shaped tube type as well as straight tube type, the necessary side part is elliptical in cross section corresponding to the side where narrow frame is required By processing, it is possible to realize the ultra-narrow frame required by the product market and customers.
In addition, since the shape of the elliptical fluorescent tube is changed by, for example, crushing the circular fluorescent tube, the cross-sectional area that allows sufficient normal glow discharge is maintained even when processed into an elliptical shape. It is possible to keep the increase in the pressure of the sealed gas due to. Therefore, there is no significant difference in photoelectric characteristics compared to the circular fluorescent tube before ellipse processing, and the photoelectric characteristics are within + 15% for lighting start voltage, within + 10% for driving voltage, and within ± 15% for average tube surface luminance. Therefore, it is possible to set the optical design and the conditions of the illumination device as in the conventional case. Further, when the elliptical shape has a minor axis / major axis ratio of less than 0.6 to less than 1.0, the ellipsoid workability can be improved.
According to the liquid crystal display device of the present invention, it has an ultra-narrow frame and has electro-optical characteristics that are comparable to conventional liquid crystal display devices, yet has high brightness, high uniformity, and good oblique viewing angle direction. It is possible to realize a transmissive liquid crystal display device having a high display quality and a transmissive liquid crystal display device with a reflection function.
Embodiments 1 to 3 of the liquid crystal display device of the present invention will be described below with reference to the drawings.
In the first embodiment, the configuration of the liquid crystal display device of the present invention and the examination results regarding the optical sheet provided on the light guide of the liquid crystal display illumination device used therefor will be described.
First, the configuration of the illumination device for liquid crystal display and the liquid crystal display device of the present invention will be described.
FIG. 1 is a cross-sectional view showing the main structure of the liquid crystal display device of the present invention, and FIG. 2 is a top view of the liquid crystal display device. 1 is a cross-sectional view taken along the line AA ′ of FIG. Moreover, the cross section of the said FIG. 6 and FIG. 7 has also shown the cross section of the part corresponding to the AA 'line part of FIG.
In FIG. 1, the liquid crystal display device 100 has a liquid crystal panel 20 disposed on a lighting device 10B for liquid crystal display, similarly to the liquid crystal display device 200 shown in FIG. This illuminating device 10B includes an elliptic fluorescent tube 1B, a light scattering resin portion 2B as a light scattering plate member, a reflection plate 3, a light guide 4B, and diffusion sheets 5-7. .
The elliptical fluorescent tube 1B is a linear light source that irradiates light to the light incident end face 4c of the light guide 4B. The fluorescent tube 1B has a long axis direction of the fluorescent tube 1B and light incident on the light guide 4B within a range surrounded by the light incident end surface 4c of the light guide 4B, the light scattering resin portion 2B, and the reflection plate 3. It arrange | positions so that the perpendicular line direction with respect to the end surface 4c may become a substantially right angle.
The light scattering resin portion 2B has portions 2a and 2b having different thicknesses in a stepped manner. In the present embodiment, a polycarbonate (PC) resin added with titanium oxide or zinc oxide as a light scattering material is used as the light scattering resin.
The reflection plate 3 is provided on the lower surface 4b side of the light guide plate 4B, and has a function of reflecting light returning from the light guide 4B and light from the elliptical fluorescent tube 1B back to the light guide 4 side. .
The light guide 4B propagates the light incident from the one end face 4c therein and emits the light uniformly from the upper surface 4a to the liquid crystal panel 20 side. The light guide 4B has a thin plate portion 4d of a translucent resin portion in a state where the upper surface 4a side protrudes outward with a predetermined thickness. A thin portion 2b of the light scattering resin portion 2B and a thin plate portion 4d of the translucent resin portion overlap each other in the thickness direction. A polymethyl methacrylate (PMMA) resin is used as the translucent resin portion (transparent resin). The thin plate portion 4d is received from the lower side at the portion where the thickness of the light scattering resin portion 2B is thin. An effective display area of the liquid crystal panel 20 surrounded by the black matrix 15 of FIG. 2 is an end portion (end surface b of the thin plate portion 4d) of the overlapping portion between the thin portion 2b of the light scattering resin portion 2B and the thin plate portion 4d. 21 (inner side from boundary a; area A in FIG. 1).
The optical sheet in which the lower diffusion sheet 5 / prism sheet 6 / upper diffusion sheet 7 is combined is provided on the upper surface 4a side of the light guide plate 4B, and optical processing such as diffusion is performed on the light from the light guide plate 4B. In the first embodiment, D123 manufactured by Tsujiden is used as the lower diffusion sheet 5, BEFII manufactured by Sumitomo 3M is used as the prism sheet 6, and D117 manufactured by Tsujiden is used as the upper diffusion sheet 7.
The liquid crystal panel 20 is provided with a liquid crystal layer (not shown) between the upper glass substrate 13 and the lower glass substrate 12 each provided with an electrode, and a front side polarizing plate 14 and a back side polarizing plate 11 are provided on both sides thereof. Is provided. By applying a voltage to the liquid crystal layer to change the alignment state of the liquid crystal molecules, the light irradiated from the illumination device 10B is modulated to change the polarization state and pass through the polarizing plates 11 and 14, or the polarizing plate Since it is scattered and absorbed by 11 and 14, a transmissive display is obtained.
The illuminating device 10B is disposed in a concave back-side casing 31 made of metal, and is fixed to the back-side casing 31 by double-sided tapes 41 and 42 as fixing auxiliary materials. The double-sided tape 41 is disposed below the end surface 4c, which is an effective incident end surface of the light guide 4B, and is disposed between the reflective sheet 3 and the bottom surface of the casing 31, and the double-sided tape 42 is a light scattering property of the light guide plate 4. It arrange | positions between the resin part 2 and the side surface of the back side housing 31. FIG.
Further, the lighting device 10B and the back housing 31 are covered with an inner housing 32 made of resin and having an edge portion 32a provided so as to protrude from the side surface onto the lighting device 10B. The lighting device 10 is fixed to the lower surface of the edge 32 a of the inner housing 32 by the double-sided tape 43 disposed on the inside. The liquid crystal panel 20 is mounted on the edge 32 a of the inner housing 32, and the liquid crystal panel 20 is fixed to the upper surface of the edge 32 a of the inner housing 32 by the double-sided tape 44 disposed at the end of the lower substrate 11. It has become.
Further, the illumination device 10B, the liquid crystal panel 20, the back housing 31 and the inner housing 32 have a lid-shaped front side in which an effective display region 21 (boundary surface a) of the liquid crystal panel 20 and a black matrix region 15 surrounding the periphery are opened. A housing 33 is covered.
In the liquid crystal display device 100 according to the first embodiment, in the front view direction, the light scattering ability of the light scattering resin portion 2 is optimized and guided in the same manner as the conventional liquid crystal display device 200 shown in FIG. Optimizing the combination of the diffusion sheets 5 and 7, which are optical sheets disposed on the body 4B, appropriately scattering the light with the diffusion sheets 5 and 7, and the light scattered by the light scattering resin portion 2B; High display quality can be realized by balancing the light scattered by the embossed pattern on the lower surface 4b of the light guide 4B made of transparent resin.
Furthermore, in the liquid crystal display device 100 of the present embodiment, at an oblique viewing angle, the outer end (boundary surface) of the overlapping portion of the light scattering resin portion 2b where the thin plate portion 4d is thin and the thin plate portion 4d of the translucent resin portion. The end surface b) of the thin plate portion 4d is disposed outside the effective display area 21 (inner side surface from the boundary a), so that even when the viewing angle direction is inclined by an angle d and observed from an oblique viewing angle c, The outer end (boundary surface; end surface b of the thin plate portion 4d) of the overlapping portion between the light scattering resin portion 2b having a small thickness and the thin plate portion 4d of the transparent resin portion is not visually observed. Therefore, the luminance is not discontinuous in the peripheral portion, and a good display state can be obtained.
Next, the result of examining the combination of optical sheets used in the liquid crystal display illumination device 10B of the present invention will be described.
In the combination of the optical sheets in the present embodiment, in particular, the upper diffusion sheet 7 is changed to a light transmissive one as compared with the conventional liquid crystal display device 200.
In the liquid crystal display device 200 of FIG. 6, the distance from the effective display area A (boundary surface a; end surface b of the thin plate portion 4d) of the liquid crystal panel 20 to the inner end (right end in the drawing) of the light scattering resin portion 2 is about 2 mm. In order to make this optical distance difficult to see the boundary surface by combining the diffusion sheets 5 and 7, it is necessary to combine the diffusion sheets 5 and 7 that can be expected to have an appropriate scattering effect. For example, it was necessary to use a turbidity of about 77% such as D120 manufactured by Tsujiden.
On the other hand, in the liquid crystal display device 100 of the present embodiment, the distance from the effective display area (boundary surface a) to the inner end portion of the light scattering resin portion 2 is changed by changing the shape of the lamp rubber holder or crossing the manufacturing of the lamp. It was possible to shorten it to about 1 mm by considering the production specifications and using the elliptical fluorescent tube 1B. As a result, even when the turbidity of the upper diffusion sheet 7 is lowered, a clear color change due to a difference in transmission spectrum is not observed as in the conventional liquid crystal display device 200, and the uniformity is high and continuous. Lighting can be performed.
In the illuminating device 10B for liquid crystal display of the present embodiment, the upper diffusion sheet 7 has a turbidity of 35% (D117UE manufactured by Tsujiden Co., Ltd.), which is a significant improvement in luminance as compared with the case where a high turbidity is used. It becomes possible. Moreover, since the thing with a low turbidity can be used as the upper diffusion sheet 7, a choice can be expanded. Furthermore, instead of the upper diffusion sheet 7, a selective polarization reflection film such as DBEFD or DRPHF manufactured by Sumitomo 3M Co. can be used.
Table 1 below shows the results of measuring the luminance with different combinations of diffusion sheets.
In Table 1, the combination of the upper diffusion sheet 7 / prism sheet 6 / lower diffusion sheet 5 constituting the optical sheet, the turbidity of each of the diffusion sheets 5 and 7, the luminance at the center of the lighting (illuminating device), The luminance at the center of the liquid crystal panel and the luminance increase rate compared with the conventional liquid crystal display device are shown.
As the upper diffusion sheet 7, for example, D117TF (turbidity 64%) and D117TY (turbidity 73%) are used by Tsujiden Co., and the light-up 100TL4 (turbidity 38%), light-up 100TL2 (turbidity 38%) are used. Turbidity 25%) was used. Various combinations of the upper diffusion sheet 7 were also examined. In the conventional liquid crystal display device, D123 manufactured by Tsujiden Corporation was used, but in this embodiment, D114 manufactured by Tsujiden Corporation and high turbidity diffusion sheets 100MXE and 100SXE100LSE manufactured by Kimoto Corporation were used.
As can be seen from Table 1 above, in the present embodiment, various sheet combinations can be used with higher brightness than the conventional combination of optical sheets. For example, five sample numbers in the first row from the top. 1 to 5, when 100SXE is used as the lower diffusion sheet 5, three sample Nos. When combined with the upper diffusion sheet 7 having a lower turbidity than those of the conventional examples shown in Nos. 26 to 28, the luminance can be improved by about + 28% to + 32%. The lighting center brightness is 4593CD / m in the past. 2 ~ 4722cd / m 2 In the present invention, the lighting luminance is 6037 cd / m. 2 ~ 6222cd / m 2 It was possible to greatly improve the brightness.
Further, when the transmissive liquid crystal panel 20 is mounted on the lighting device 10B, in the conventional example, 355 cd / m. 2 ~ 375cd / m 2 479 cd / m for the degree 2 ~ 494cd / m 2 As a result, the brightness was greatly improved. Conventionally, 500 cd / m without using a selective polarization reflection film 2 There are almost no examples of a liquid crystal display device that achieves a brightness approaching the above, and it is possible to provide a very useful lighting device 10B and a liquid crystal display device 100 using the same for applications in which maximum brightness is important.
For this effect, the combination of the lower diffusion sheet 5 and the upper diffusion sheet 7 may be optimized. As shown in 21 to 25, when D123 which has been conventionally used as the lower diffusion sheet 5 and the upper diffusion sheet 7 with low turbidity are combined, the luminance increase rate is about + 6% to + 11% compared with the conventional case. Obtained.
Furthermore, in this embodiment, it was considered that a higher luminance increase rate than that of the conventional example could be obtained by variously changing the turbidity of the upper diffusion sheet 7. As the upper diffusion sheet 7, 100SXE (turbidity 89%), 100MXE (turbidity 89%), 100LSE (turbidity 84%) manufactured by Kimoto Co., D114 (turbidity 81%), D123 (turbidity) manufactured by Tsujiden 82%). As the lower diffusion sheet 5, D117UE (turbidity 35%), D117TF (turbidity 64%), D117TY (turbidity 73%) manufactured by Tsujiden Co., Ltd., 100TL2 (turbidity 29%), 100TL4 (turbidity) manufactured by Kimoto Co., Ltd. Degree 46%) was used.
Five sample numbers in the second row from the top. As shown in 6 to 10, when 100SXE was used as the upper diffusion sheet 7, a brightness increase rate of about + 28% to 32% compared to the conventional case was obtained. In addition, five sample numbers in the third row from the top. As shown in 11 to 15, when 100 MXE was used as the upper diffusion sheet 7, a luminance increase rate of about + 24% to 30% compared with the conventional case was obtained. In addition, five sample Nos. In the third row from the bottom. As shown in 16 to 20, when 100 LSE was used as the upper diffusion sheet 7, a luminance increase rate of about + 28% to 25% compared with the conventional case was obtained. Furthermore, five sample numbers in the second row from the bottom. As shown in 21 to 25, when D114 is used as the upper diffusion sheet 7, a luminance increase rate of about + 15% to 18% is obtained compared to the conventional case, and when D123 is used as the upper diffusion sheet 7, The brightness increase rate was about + 7% to 11% compared to the conventional case.
As shown in Table 1, with respect to the turbidity of the lower diffusion sheet 5, the turbidity of D123 manufactured by Tsujiden, which has been conventionally used, is 82%, and the turbidity used in this embodiment is 81% to 89%. %, There is almost no optical difference when viewed from the turbidity axis.
However, as the upper diffusion sheet 7, conventionally used turbidity is 76% to 79%, whereas that used in the present embodiment is turbidity 29% to 73%. As compared with the case, a material having a very wide range can be used. The expansion of the range of the upper diffusion sheet that can be used in this way is very effective for the demands of the product market. It can be used for a wide range of applications that require balanced properties.
Furthermore, since it is not necessary to use a selective polarization reflection film that has been used conventionally in order to achieve high brightness of the lighting device 10B and the liquid crystal display device 100 using the same, it is possible to reduce the cost. It is possible to provide a high-luminance liquid crystal display illuminating device 10B and a liquid crystal display device 100 using the same up to applications where an inexpensive illuminating device 10B and a liquid crystal display device 100 using the same are required.
By the way, as a special product market, in open car and racing car applications, especially when driving a vehicle under high illuminance during the day, if the driver wears sunglasses or uses a helmet face shield, The light transmittance decreases due to light absorption of these materials. As a result, since the display screen of the liquid crystal display device looks dark, it is strongly required to improve visibility in such applications.
For such applications, it is necessary to meet market requirements by improving the brightness of the liquid crystal display device over that of the conventional example. For this purpose, it is conceivable to increase the transmittance of the conventional liquid crystal panel 20 or increase the luminance of the illumination device, but it is not easy to increase the transmittance of the liquid crystal panel 20. This is because, in order to improve the transmittance of the liquid crystal panel 20, the gate line and the source line wired in the liquid crystal panel 20 are thinned and the TFT is miniaturized to substantially increase the pixel area. This is because there is no choice but to improve the transmittance. When such a measure for improving the transmittance is taken, the fluctuation margin (manufacturing margin) of the manufacturing process is reduced, and therefore, the manufacturing process must be managed and inspected very strictly. Further, when a process condition exceeding the fluctuation margin occurs for some reason, there is a possibility that the defect rate of the liquid crystal panel 20 is greatly increased and the manufacturing cost is increased.
Thus, in order to maintain an appropriate manufacturing margin with respect to the manufacturing process of the liquid crystal panel 20, improvement in the transmittance of the liquid crystal panel 20 cannot be expected. Attention was focused on increasing the absolute amount of light transmitted through the conventional liquid crystal panel 200 by matching the optical axis emitted from the illumination device 10B with the polarization axis of the back-side polarizing plate 11 of the liquid crystal panel 20.
Specifically, instead of the lower diffusion sheet 5 of the lighting device 10B, a light that is emitted from the lighting device 10B is formed by arranging a selective polarization reflection film on the outermost surface to form an optical sheet and recycling the light. Can be aligned with a specific polarization axis. Such a method is referred to herein as a measure for improving effective luminance by a selective polarization reflection method. The case where this selective polarization reflection method is applied to the present invention will be described below.
Table 2 below shows the results of measuring the luminance in the case where an optical sheet is configured by arranging a selective polarization reflection film on the outermost surface instead of the lower diffusion sheet 5 of the illumination device 10B.
In Table 2, the combination of the selective polarization reflection film / prism sheet 6 / lower diffusion sheet 5 constituting the optical sheet, the turbidity of the diffusion sheet, the effective luminance at the center of the lighting (illuminating device), and the center of the liquid crystal panel The luminance increase rate compared with the conventional liquid crystal display device 200 is shown.
Conventionally, the optical sheet configuration used for the effective brightness improvement measure by this selective polarization reflection method is DRPFH / BEF2 / D123 from the outermost surface side. DRPFH is a special optical film manufactured by Sumitomo 3M Co., which is a selective polarizing reflection film having appropriate diffusivity, and is appropriately diffused by the lower diffusion sheet D123 and further scattered by the selective polarizing reflection film DRPFH. Brightness can be increased while maintaining light properties.
With this brightness enhancement method, the lowermost sample No. As shown in Fig. 38, the lighting (illumination device) has a center effective luminance of 6601 cd / m. 2 , LCD panel center brightness at 524cd / m 2 Was obtained.
On the other hand, in the present invention, four sample Nos. In the second row from the top. As shown in 34 to 37, even if the same DRPHF is used, the lighting center effective luminance is 7122 cd / m. 2 ~ 7927cd / m 2 Liquid crystal panel central brightness of 566 cd / m 2 ~ 629cd / m 2 As a result, it was possible to achieve a luminance increase rate of 8% to 20% compared to the conventional technology.
Furthermore, when DBEFD made by Sumitomo 3M Co. is used as another selective polarizing reflection film, the five sample Nos. As shown in 29 to 35, the luminance increase rate was 8% to 29% compared to the conventional technology. This DBEFD has less light scattering than DRPFH, and DBEFD is more advantageous as a luminance increase in the front direction. Conventionally, in order to obscure luminance continuity and chromaticity change around the frame, it has been necessary to use an appropriate light scattering property of DRPFH. In the present invention, such low light scattering DBEFD is used. In combination, it has become possible to further increase the brightness.
According to the liquid crystal display device of this embodiment using DBEFD as the polarization selective reflection film, the actual measurement value is 700 cd / m. 2 It can be seen that ultra-high brightness approaching that of the camera can be obtained, and that it can sufficiently cope with in-vehicle use for special purposes. Note that the actual required brightness is not a numerical value but a user's sense, so what cd / m 2 It is not clear whether it is 600 cd / m 2 Is considered necessary. Even in consideration of this, the liquid crystal display illumination device 10B of the present invention and the liquid crystal display device 100 using the same can sufficiently cope with special applications.
Furthermore, even for the same open car or similar motorcycle application, a method of improving the visibility by another method is conceivable. In the above description, a case where a transmissive liquid crystal panel is used as the liquid crystal panel 20 has been described. Further, a reflective function having a function of performing display by partially using reflected light in the transmissive liquid crystal panel. There are also transmissive liquid crystal panels.
The characteristic of the liquid crystal display device using this transmissive liquid crystal panel with a reflection function is that during the daytime when the sunlight is strong, the light reflected from the display-controlled liquid crystal panel and the light transmitted through the liquid crystal panel are combined. By observing the image, the brightness of the liquid crystal display generally depends on the illuminance of the external light, and the natural feeling of the reflected light is harmonized with the human visual perception. This liquid crystal display device is called, for example, an advanced liquid crystal display device.
The case where this advanced liquid crystal display device is applied to the present invention will be described in detail below.
Table 3 below shows the results of measuring the luminance when a transmissive liquid crystal panel with a reflection function is used instead of the transmissive liquid crystal panel.
In Table 3, the combination of the selective polarizing reflection film / prism sheet 6 / lower diffusion sheet 5 constituting the optical sheet, the turbidity of the diffusion sheet, the luminance at the center of the liquid crystal panel, and the comparison with the conventional liquid crystal display device Brightness increase rate.
The transmittance of the transmissive liquid crystal panel with a reflective function is about 53% as compared with the transmissive liquid crystal panel. Here, since a measurement method that takes external light into account is not used, luminance that does not include a reflected light component is shown. However, in an actual usage environment, it is considered that there is sufficient external light. It is more advantageous than the data shown.
The lowest sample No. in Table 3 above. As shown in FIG. 48, conventionally, the panel center luminance is 284 cd / m. 2 It has become. The general requirement level is 250 cd / m 2 Therefore, there is no problem, but further improvement in luminance is desired.
In order to solve this problem, the following three methods are conceivable. The first is to increase the brightness by reducing the reflective function and bring it closer to the transmissive type. The second is to improve the reflective function and increase the correlation by changing the ambient light illuminance. Is a method in which the luminance is improved by the illumination device 10B while maintaining the current reflection function.
Since there is a demand for maintaining appropriate visibility even under outside light, an appropriate reflection function is required, and the reflection function cannot be deviated until the visibility is deteriorated. In the first method, when the ambient light illuminance becomes very high, the absolute difference from the ambient light illuminance cannot be complemented even if the brightness is increased by increasing the transparency. In addition, the second method provides a strong correlation with the illuminance of external light, but it cannot eliminate the dependence on the external light spectrum that is inherent to the reflection method, resulting in a faded display state that is visually recognized by the observer. In addition to the poor impression, the panel transmittance deteriorates under low and medium illuminance, so that the illumination light is not fully utilized and the display becomes dark. Therefore, the third method was examined below.
As a result, the four sample numbers in the second row from the top of Table 3 above. As shown in 44 to 47, even when the same DRPFH as the conventional polarizing reflection film is used, the luminance increases by 8% to 20% compared to the conventional, and the top five sample Nos. As shown to 39-43, when DBEFD was used, the brightness | luminance was able to be raised 11%-34% compared with the past. The LCD panel central brightness is stable at 350 cd / m. 2 Since the above brightness | luminance can be implement | achieved, it can respond to the brightness improvement request | requirement of a product market.
Further, in the liquid crystal display illumination device 10B of the first embodiment described above, the luminance is not improved by an easy method such as increasing the lamp current of the fluorescent tube 1B used in the illumination device 10B. Luminance can be improved without affecting the lifetime of the lighting device 10B, and high reliability can also be provided.
In the first embodiment, the combination of the lamp configuration of the liquid crystal display device 100 and the optical sheet, that is, when the turbidity of the upper diffusion sheet 7 is variously changed to improve the transparency (Table 1), the lower diffusion sheet 5 When the selective polarization reflection film is arranged instead of the optical axis of the light emitted from the illumination device 10B so as to align with the specific polarization axis (Table 2), the selective polarization reflection film is arranged instead of the lower diffusion sheet 5. The case of obtaining appropriate visibility even under outside light (Table 3) has been described. In Embodiment 2, the structure of the elliptical fluorescent tube used in the liquid crystal display illumination device 10B of the present invention and the electro-optical characteristics thereof are described. explain.
First, the specific structure of the elliptical fluorescent tube 1B of FIG. 1 will be described in detail with reference to FIGS.
FIG. 3 is a plan view showing the main structure of the fluorescent tube assembly of the elliptical fluorescent tube 1B of FIG. 1, FIG. 4 (a) is a cross-sectional view taken along line BB ′ of FIG. 3, and FIG. 4 (b). FIG. 4 is a sectional view taken along the line CC ′ of FIG. 3.
In FIG. 3, this fluorescent tube assembly 50 is a U-shaped fluorescent tube having two bent portions, and a high-voltage side electrode 55 provided at one end is connected to solder 56 and A low voltage side electrode 58 provided at the other end is connected to a connector 62 for connection with an inverter circuit (not shown) via a high voltage side harness 57, and solder 60 and a low voltage side harness 61. It is connected to the connector 62 via The ends of the fluorescent tubes (glass tubes) provided with the electrodes 55 and 58, the solders 56 and 60, and the ends of the harnesses 57 and 61 are surrounded by the high-voltage side rubber holder 54 and the low-voltage side rubber holder 59. Each is covered.
In this fluorescent tube assembly 50, the short side 51 processed into an elliptical shape is connected to the high output side (high voltage side) from the inverter circuit, and the location electrically called the hot side is true. It is processed from a circular shape to an elliptical shape. Needless to say, the short side 52 and the long side 53 connected to the low output side (low voltage side) from the inverter circuit may be processed, but in the second embodiment, the high output side from the inverter circuit is used. In order to achieve a very narrow frame with respect to the short side portion 51, only the short side 51 is processed to have an elliptical shape as shown in FIG. The short side 52 and the long side 53 are not processed in shape, and remain in a perfect circle shape as shown in FIG.
In the second embodiment, the reason why the elliptical processing is performed on the short side portion 51 on the high voltage side of the fluorescent tube is as follows. The discharged fluorescent tube can be expressed as a resistance in an electrical equivalent circuit. In the fluorescent tube whose shape has been changed as in the second embodiment, the elliptical portion has a slightly high resistance, and the perfect circular portion can be expressed as a conventional resistance value.
When the inner diameter of the fluorescent tube is reduced or the gas pressure is increased, the lighting sustaining voltage is increased and the discharge maintaining margin is decreased. In this case, in order to maintain the discharge state of the fluorescent tube, the high resistance portion (elliptical shape portion) is arranged on the high voltage side of the fluorescent tube and the low resistance portion (round shape portion) is arranged on the GND side. Is advantageous. This can be easily understood by performing a PWM dimming test.
Even in the case of a perfect circular fluorescent tube, in the low DUTY state, when the tube surface luminance is compared between the high voltage side and the GND side, the luminance on the high voltage side is higher. For the fluorescent tube of Embodiment 2 with one of the short sides subjected to ellipse processing, the elliptical side is connected to the low voltage side, the perfect circle side is connected to the high voltage side, and the PWM dimming test is performed similarly. When driving in a low DUTY state, the discharge becomes unstable at the portion processed into an elliptical shape, and a phenomenon called a so-called snake phenomenon was observed. This phenomenon appeared in tests at room temperature. Therefore, it is clear that when a similar test is performed at a low temperature, the discharge does not occur well.
However, as in the second embodiment, when the elliptical shape side is connected to the high voltage side and the perfect circle shape side is connected to the low voltage side, similarly to the conventional fluorescent tube not subjected to the elliptical shape processing, A stable discharge state could be maintained. This indicates that an effect that could not be predicted by those skilled in the art was obtained.
In order to process the short side portion of the circular fluorescent tube into an elliptical shape, a dedicated elliptical processing jig set slightly higher than the softening temperature of the glass used can be used. Since the glass softening temperature is about 700 ° C., the region to be processed is pre-heated once with a burner, and the glass tube is slowly crushed to a predetermined size by an elliptical processing jig heated to about 800 degrees. Go.
When performing the ellipse processing, it is necessary to pay attention to the electrode part. Since the electrodes 55 and 59 are heated to a very high temperature by the heat treatment, the thermal deterioration of the rubber holders 54 and 59 is accelerated when the inner surface of the glass tube and the electrodes 55 and 58 come into contact with each other. Since the diameter of the electrode is 1.0 mm to 1.4 mm, if the glass tube is crushed without considering the electrodes 55 and 58, the inner surface of the glass tube and the electrodes 55 and 59 come into contact with each other. Further, the electrodes 55 and 58 have a problem inherent to the manufacturing method in which it cannot be guaranteed that the glass tube and the electrodes 55 and 58 are in parallel. Therefore, in the second embodiment, the crushing process is not performed on the electrode portion.
Next, the dimensions and electro-optical characteristics of a conventionally used circular fluorescent tube and the elliptic fluorescent tube of Embodiment 2 will be described.
A feature of the elliptical fluorescent tube of the second embodiment is that the high voltage side of the fluorescent tube is subjected to ellipse processing. The person skilled in the art feels empirically that, when the process of lighting the fluorescent tube is observed, when a normal glow discharge is generated inside the fluorescent tube, the high voltage side to the low voltage side (GND side) of the fluorescent tube. The discharge grows. It is also known that the lighting start voltage varies depending on the diameter of the fluorescent tube. However, as in the second embodiment, a technique for an irregular fluorescent tube having an elliptical part and a circular part is not known. Therefore, the results of studies conducted by the present inventors on the electro-optical characteristics of such an irregular fluorescent tube will be described below.
Tables 4 and 5 below show the dimensions of the conventional perfect circular fluorescent tube before the ellipse processing and the evaluation results of its electro-optical characteristics.
In Table 4 above, the pipe diameter (outer diameter) is shown in the upper stage, the inner diameter of the pipe is shown in the lower stage, and the short side gas to which the pipe surface circumference, pipe inner diameter, pipe inner circumference, and ellipse processing are applied. The figure shows the volume, the gas volume on all sides, and the volume ratio on the short side / all sides.
In Table 5 above, as photoelectric characteristics, the tube voltage, the inverter output voltage at the start of lighting, the transformer voltage at the start of lighting, the tube surface luminance, the luminance at the center of the lighting (illumination device), and the center of the liquid crystal display (display device) The result of having measured the brightness | luminance of the part is shown.
In Tables 4 and 5 and Table 9 below, the lighting start voltage indicates data measured at room temperature −30 ° C., and the tube surface brightness indicates data measured at room temperature + 25 ° C. and current 6.5 mArms. . As the fluorescent tube lighting inverter, HIU-288 manufactured by Harrison Toshiba Lighting Co., Ltd., which uses a ballast capacitor 22pF, was used. The luminance measurement was performed using BM-7 manufactured by Topcon Corporation.
The fluorescent tube of Embodiment 2 has a U-shape with a short side of 80 mm and a long side of 145 mm, and the total length is 305 mm. The diameter is 2.4 mm, the inner diameter is 1.8 mm, and the glass thickness is 0.3 mm. This is because, when the glass thickness is 0.3 mm or less, when the glass is bent in a U shape, the glass deformation of the bent portion becomes extreme, and the discharge is affected. For this reason, the second embodiment uses a glass tube having a thickness of 0.3 mm. If the processing method of the bent portion is improved, it is considered possible to use a glass tube having a thickness of 0.25 mm in the near future.
Table 6 below shows the minor axis / major axis ratio and dimensions of the outer shape of the elliptical fluorescent tube 1B.
In Table 6 above, the dimensions of the short axis / long axis ratio (ratio), the elliptical short axis radius, the elliptical short axis diameter, the elliptical long axis radius, the elliptical long axis diameter, the elliptical tube cross-sectional area, and the tube cross-sectional area are true. The circle ratio and the true circle equivalent diameter are shown.
Tables 7 to 9 below show the analysis of dimensions such as the inner diameter and gas pressure, and the evaluation results of the electro-optical characteristics of the inner shape of the elliptical fluorescent tube 1B. Fluorescent tubes (sample Nos. A to D) subjected to elliptical processing with different short axis / long axis ratios with respect to the short side 51 on the high voltage side, and the above-described Tables 4 and 5 This shows a conventional perfect circular fluorescent tube (sample No. E) that has not been subjected to elliptical processing.
In Table 7 above, the dimensions of the inner diameter are the minor axis / major axis ratio (ratio), the ellipse minor axis radius, the ellipse minor axis diameter, the ellipse major axis radius, the ellipse major axis diameter, the elliptic tube cross-sectional area, and the tube cross-sectional area true. The circle ratio and the true circle equivalent diameter are shown.
Table 8 shows the gas volume and the volume reduction rate as dimensions, and the photoelectric characteristics when the short axis ratio / long axis ratio are changed as the tube voltage, the inverter output voltage at the start of lighting, and the lighting start time. Shows the transformer voltage.
In Table 9 above, as the photoelectric characteristics, the tube surface brightness of the perfect circle part, the tube surface brightness when the elliptical part is viewed from the minor axis direction, the tube surface brightness when the elliptical part is viewed from the major axis direction, The results of measuring the luminance at the center of the lighting (illuminating device), the luminance at the center of the liquid crystal display (display device), and the rate of increase in luminance are shown.
As shown in Tables 6 to 8 above, when processing into an elliptical shape, the internal cross-sectional area of the glass tube is reduced as compared with a perfect circular shape. At this time, since the gas sealed in the glass tube has no other place to escape, the internal gas pressure rises as much as the cross-sectional area is reduced. This change in internal gas pressure has the greatest electro-optical effect.
Further, as shown in Table 8 above, as electrical characteristics, the tube voltage and the lighting start voltage during lighting increase as the minor axis / major axis ratio of the elliptical shape decreases.
Furthermore, as shown in Table 9 above, as the optical characteristic, when the minor axis / major axis ratio of the elliptical shape is reduced, the charged gas pressure is increased, so that the luminance is increased. Also, as shown in Table 9 above, the luminance when the elliptical portion is viewed from the short axis direction A shown in FIG. 4 is higher than that when viewed from the long axis direction B. There are features. Therefore, the long axis direction with low luminance is set to the notch portion direction (the thin plate portion 4d side) of the light guide body 4B so that light from the short axis direction with high luminance is incident from the effective incident end face 4c of the light guide body 4. By arranging and arranging the major axis direction and the perpendicular direction of the incident end face 4b to be substantially perpendicular, the amount of light incident on the light guide can be increased.
In addition, since the fluorescent plate has a high luminance, the thin plate portion of the light guide 4B is made of a light scattering material to reduce the luminance so that the light directly irradiated from the thin plate portion 4d does not affect the display. Since the added resin is used, if the long axis direction with low luminance can be lowered toward the thin plate portion in this way, the luminance around the frame can be obtained even if the light scattering resin portion 2B is shortened. The uniformity will not deteriorate. Further, since the optical margin is larger than the conventional one, even if the manufacturing conditions of the light-scattering resin part 2 are slightly deviated, it is not necessary to strictly inspect the product, and the cost of the light guide can be reduced. it can.
As shown in Table 8 above, it can be seen that the electrical characteristics are not disadvantageous even when processed into an elliptical shape. The fluorescent tube voltage and the lighting start voltage show an upward trend, but the rate of increase is 15% or less, more preferably 10% or less compared to the case of a perfect circle, and the lighting margin set at the time of designing the inverter Can be driven sufficiently. Therefore, there is no optical disadvantage, and an ultra-narrow frame illumination device can be realized within a range that is sufficiently acceptable electrically.
As shown in Table 8 and Table 9 above, when the minor axis / major axis ratio of the elliptical shape is reduced, the tube surface brightness in the minor axis direction of the elliptical fluorescent tube increases, and the sealed gas pressure increases. The central brightness of the lighting increases due to the synergistic effect. When the case of using the configuration of the conventional optical sheet was compared, for example, sample No. with a minor axis / major axis ratio of 0.63 of the outer shape of the fluorescent tube was obtained. In B, the brightness increased by 7%. As a result, it was confirmed that processing into an elliptical shape effectively contributed to lighting luminance. This increase in lighting luminance is naturally effective even when a liquid crystal panel is mounted, and a luminance increase rate reflecting the increase in lighting luminance can be obtained.
For the optimal range of the elliptical shape, it is necessary to consider the structural factor of the thickness of the lighting device. The depth of the thin plate portion 4d of the light guide 4B in which the fluorescent tube 1B is disposed is about 3.0 mm. Therefore, when the minor axis / major axis ratio shown in Table 6 is 0.53, the ellipse major axis has a diameter of 2.99 mm, which is a marginal dimension. Considering mass production in practice, the design of zero clearance is not preferable, and it is not preferable that ellipses are processed to this ratio. Further, when the minor axis / major axis ratio is 0.63, the ellipse major axis has a diameter of 2.88, and the design margin is very small, but it is within the possible range in consideration of the elliptical processing tolerance of the fluorescent tube. Therefore, the range of ellipse processing (lower limit of the short axis / long axis ratio) is, as viewed from the outer shape of the fluorescent tube, the short axis / long axis ratio is between 0.53 and 0.63, and 0.63 One numerical value of 0.6 that is close to is conceivable. Therefore, in the elliptical fluorescent tube 1B of the present invention, the elliptical processing range is preferably 0.6 or more and less than 1.0 as the minor axis / major axis ratio.
As described above, by using the elliptical fluorescent tube 1B, it is possible to realize the illumination device 10B having a high brightness and a very narrow frame while suppressing the electrical influence to + 10% or less. As a result, it is possible to realize a transmissive high-brightness liquid crystal display device and to achieve a high luminance up to a practical luminance range even in a transmissive liquid crystal display device with a reflective function. Therefore, it is possible to provide an excellent liquid crystal display illumination device and various liquid crystal display devices that can meet the luminance performance and display quality required by the product market and customers.
In the above description, an example in which the present invention is applied to a U-shaped fluorescent tube in plan view has been described. However, an L-shaped, B-shaped, straight tube-shaped fluorescent tube or a combination thereof is used. Needless to say, the present invention is applicable.
In Embodiment 1 described above, when the turbidity of the upper diffusion sheet 7 is variously changed in order to improve the transparency, the configuration of the illumination device of the liquid crystal display device 100 and the combination of the optical sheets (Table 1), the lower diffusion When the selective polarization reflection film is arranged instead of the sheet 5 and the optical axis of the light emitted from the illumination device 10B is aligned with the specific polarization axis (Table 2), the selective polarization reflection film is arranged instead of the lower diffusion sheet 5 In the second embodiment, the structure of the elliptical fluorescent tube 1B according to the present invention and its electro-optical characteristics, that is, the co-planarity in the plan view will be described. The shape of the letter and the shape of the elliptical section are only on the high pressure side, the long axis direction with low luminance is located on the thin plate portion 4d side, the short axis direction with high luminance is arranged on the incident end face 4c side, / Long axis ratio of 0.6 or more In the third embodiment, the arrangement positional relationship of the fixed auxiliary materials used in the liquid crystal display device 100 of the present invention and the result of measuring the cross-sectional luminance from the vicinity of the end of the lighting device to the center are described in the third embodiment. Will be described.
First, the positional relationship of the fixed auxiliary materials in the liquid crystal display device 100 of the third embodiment and the conventional liquid crystal display device 200 will be compared and described.
In the conventional liquid crystal display device 200 shown in FIG. 6, when the back-side casing 31 and the reflection sheet 3 (reflection plate) of the lighting device 10 are fixed, the light guide 4 that is away from the position where the fluorescent tube 1 is disposed is effective. It is fixed by a double-sided tape 41 as a fixed auxiliary material at a position inside the incident end face 4c.
On the other hand, in the third embodiment, as shown in FIG. 1, a double-sided tape 41 as a fixed auxiliary material is included directly under the incident end face 4c of the light guide 4B, and the fluorescent tube 1B side and the light guide 4B. Arranged across the side.
The reason why the fixed auxiliary material is preferably arranged at this position is as follows. At the position where the fixed secondary material (double-sided tape) 41 is provided, the reflective sheet 3 is slightly raised under the influence of the thickness of the fixed secondary material. For this reason, when the reflection sheet 3 is raised near the lower part of the incident end face 4c, the light guide body reflection sheet 3 is optically close at this position. As a result, the gap between the light guide back surface 4b in the vicinity of the incident end face 4c and the reflection sheet 3 is reduced, and light emitted directly from the fluorescent tube 1B or light scattered and reflected by the thin plate portion is incident from this gap. It will be less.
As in the conventional liquid crystal display device 200 shown in FIG. 6, when the fixed auxiliary material (double-sided tape) 41 is arranged on the inner side away from the incident end face 4c of the light guide 4B, the light guide near the effective incident end face 4c is obtained. Since the gap between the back surface 4b and the reflection sheet 3 is opened, light enters through the gap, and the light diffusion / scattering means (not shown) provided on the back surface 4b of the light guide feels uncomfortable over a wide area. A bright region appears, and the luminance uniformity of the lighting device 10B is deteriorated. In addition, since the position where the fixed auxiliary material is arranged varies depending on the influence of the assembly work of the lighting device 10B and the dimensions of the optical component and the housing, the reflection sheet 3 and the back surface 4b of the light guide 4B are different. As the gap becomes wider or narrower, the size of the gap cannot be controlled, and variations in display quality cannot be suppressed.
On the other hand, in the third embodiment, the arrangement position of the fixed auxiliary material (double-sided tape 41) is set, and the thickness of the fixed auxiliary material 41 effectively contributes to guide the reflecting sheet 3 at the incident end face 4c. Since the light body back surface 4b is in appropriate contact with the gap between the incident end face 4c and the reflection sheet 3, stray light incidence on the incident end face 4c can be suppressed.
In the third embodiment, double-sided tape # 6046 (product number of double-sided tape; total thickness 75 μm) manufactured by Kuramoto Sangyo Co., Ltd. was used as the fixed auxiliary materials 41 to 44. This double-sided tape is characterized by high light resistance. In general, an acrylic adhesive double-sided tape turns yellow due to ultraviolet rays emitted from the fluorescent tube 1B. However, the double-sided tape used in the third embodiment suppresses this yellowing. The details of this double-sided tape # 6046 are disclosed in, for example, Patent Document 3 (Japanese Patent Application No. 2002-182794), and thus the description thereof is omitted here. By using such a double-sided tape with strong light resistance, even if there is light that is transmitted through the reflection sheet 3 and incident on the double-sided tape 41, it is not affected optically by ultraviolet rays, so it is stable over a long period of time. Therefore, the arrangement of the optical members can be fixed, which is very effective.
Next, the results of measuring the cross-sectional luminance from the vicinity of the end to the center of the liquid crystal display lighting device of the third embodiment and the conventional lighting device 200 will be described.
Table 10 below shows the illumination device of the third embodiment in which the position of the fixed auxiliary material 41 is arranged near the lower portion of the incident end face 4c of the light guide 4B, and the position of the fixed auxiliary material 41 on the incident end face 4c of the light guide 4B. FIG. 5 is a table showing the results of comparative evaluation of the cross-sectional luminance from the frame portion to the center portion of the conventional lighting device 200 shown in FIG. 6 arranged at an inner position away from the frame. FIG. 5 is a graph of this table. It is a thing.
Table 10 above shows the distance from the frame portion to the central portion as a measurement point, and shows the relative luminance value at each measurement point when the luminance at the central portion is 100%. In FIG. 5, the horizontal axis represents the distance from the frame portion to the central portion, the vertical axis represents the relative luminance value with the central portion set to 100%, and the relative luminance of the lighting device of Embodiment 3 is represented by a solid line. The relative luminance of the conventional lighting device 200 is indicated by a dotted line.
As can be seen from Table 10 and FIG. 5, in the conventional lighting device 200, there is a sharp decrease in luminance near the incident end face of the light guide 4B and a significant increase in luminance at the frame portion of the lighting device. The brightness fluctuates up and down toward the inside of the light body. When such a change in luminance occurs, it is observed by humans as if a bright line or a black line is generated in an area where the differential value is 0 when the differential of luminance is analyzed, and the differential value is reversed.
On the other hand, in the illuminating device for liquid crystal display according to the third embodiment, the cross-sectional luminance is an ideal luminance curve, and the luminance gradually increases from the frame portion toward the center portion. The reason why the luminance change around the frame portion can be suppressed as described above is that, as described in the third embodiment, the light guide back surface 4b and the reflection are reflected near the lower part of the effective incident end surface 4c of the light guide 4B. As described in the first embodiment, the gap between the sheet 3 and the outer side of the overlapping portion of the light-transmitting resin portion constituting the light guide thin plate portion 4d and the light-scattering resin portion 2b having a small thickness is reduced. The end (boundary surface; the end surface b of the thin plate portion 4d) is shifted to the end of the light guide and arranged outside the effective display area (boundary surface a). This can be realized by processing the tube into an elliptical shape.
As described above, according to the first to third embodiments, in the illuminating device 10B in which, for example, the fluorescent tube 1B is disposed as a light source near the light incident end face 4c and the thin plate portion 4d of the light guide 4B, the portions 2a and 2b having different thicknesses are provided. The light-scattering resin portion 2B having 2b is provided with a thin portion 2b and a thin plate portion 4d which is a light-transmitting resin portion. The outer end (boundary surface; end surface b of the thin plate portion 4d) of the overlapping portion is set outside the effective display area A (boundary surface a) of the liquid crystal panel 20. Even when the liquid crystal panel is observed 20 from the oblique direction c, the boundary line of the end face b of the thin plate portion 4d is not visible, and no color change occurs in the peripheral portion. Since the fluorescent tube 1B has an elliptical cross section, the frame can be further narrowed compared to a conventional circular fluorescent tube. Accordingly, the uniformity of the light emitting surface / display surface, the luminance continuity at the viewing angle d between the boundary surface a and the oblique direction c, and the ultra-narrow frame can be both achieved, and the photoelectric characteristics can be maintained at a high level.
As described above, according to the illuminating device for liquid crystal display of the present invention, the outer end (boundary surface; end surface of the thin plate portion) of the overlapping portion of the light transmitting resin portion and the light scattering resin portion of the light guide thin plate portion is liquid crystal. Since it is set outside the effective display area of the panel, brightness continuity on the light emitting surface can be further ensured as compared with the illumination device disclosed in Patent Document 1, and a liquid crystal panel is provided on the illumination device. When the is installed, the outer edge (boundary surface) of the overlap between the translucent resin part and the light-scattering resin part can be prevented from being seen not only from the front view but also from an oblique direction. Display quality can be ensured by simple display.
Also, by using an elliptical linear light source, for example, an elliptical fluorescent tube, the dimension of the thin plate portion of the light guide can be shortened in the longitudinal direction compared to the conventional case using a circular fluorescent tube. Therefore, it is possible to realize a liquid crystal display illumination device with a very narrow frame. In addition, by arranging the long axis direction of the elliptical fluorescent tube so as to be substantially perpendicular to the direction perpendicular to the light incident surface, the tube surface luminance in the long axis direction is lower than that of the circular fluorescent tube. Therefore, the luminance change around the frame portion of the lighting device can be suppressed. Furthermore, since the tube surface luminance in the short axis direction is higher than that of the circular fluorescent tube, the amount of light incident on the light guide is increased and the luminance can be improved as a whole. Therefore, it is possible to realize a liquid crystal display illumination device with a very narrow frame, which is strongly demanded by the product market and customers, while maintaining the photoelectric characteristics of the conventional liquid crystal display illumination device and providing high brightness illumination. An apparatus can be realized.
Further, by arranging a fixing auxiliary material used for fixing the lighting device to the housing, for example, at the lower part of the incident end surface, the gap between the lower surface of the light guide near the incident end surface and the reflection sheet is made smaller or abutted. Therefore, the amount of light incident on this gap can be greatly reduced or eliminated. This suppresses or prevents the unnecessary reflection of stray light incident between the light guide entrance end surface and the reflective sheet, and reduces abnormal brightness variations and brightness changes near the light guide entrance end surface. Or it can be prevented. Therefore, by disposing the fixed auxiliary material in this positional relationship, it is possible to obtain a liquid crystal display device with better display quality than before.
In addition to straight tube types, fluorescent tubes such as U-shaped tube type, L-shaped tube type, and B-shaped tube type have elliptical necessary side portions corresponding to the sides that require a narrow frame. By processing, it is possible to realize the ultra narrow frame required by the product market and customers.
In addition, since the shape of the elliptical fluorescent tube is changed by, for example, crushing the circular fluorescent tube, the cross-sectional area that allows sufficient normal glow discharge is maintained even when processed into an elliptical shape. The increase in the pressure of the sealed gas due to can be kept small. Therefore, there is no significant difference in photoelectric characteristics compared to the circular fluorescent tube before ellipse processing. The photoelectric characteristics are within + 15% for lighting start voltage, within + 10% for driving voltage, and within ± 15% for average tube surface luminance. Therefore, it is possible to set the optical design and the conditions of the illumination device as in the conventional case. Moreover, elliptical workability can be made favorable by making elliptical shape into 0.6 to less than 1.0 in a short axis / major axis ratio.
In addition, according to the liquid crystal display device of the present invention, it has an ultra-narrow frame, electro-optical characteristics comparable to those of conventional liquid crystal display devices, high brightness, high uniformity, and from an oblique viewing angle direction. In addition, a transmissive liquid crystal display device having a good display quality and a transmissive liquid crystal display device with a reflection function can be realized.
FIG. 1 is a cross-sectional view showing a main structure of a liquid crystal display device of the present invention, and FIG. 2 is a top view of the liquid crystal display device.
2 is a top view of the liquid crystal display device of FIG. 1. FIG.
3 is a plan view showing the main structure of the fluorescent tube assembly of the elliptical fluorescent tube 1B of FIG. 1. FIG.
4A is a cross-sectional view taken along line BB ′ of FIG. 3, and FIG. 4B is a cross-sectional view taken along line CC ′ of FIG.
FIG. 5 is a graph showing cross-sectional luminance relative values from the frame portion to the center portion of the present invention and each conventional lighting device.
FIG. 6 is a cross-sectional view showing a structural example of a conventional liquid crystal display device.
FIG. 7 is a cross-sectional view showing another structural example of a conventional liquid crystal display device.
1B fluorescent tube
2B Light scattering resin part
2a Thick part
2b Thin part
4B light guide
4a Light guide top surface
4b Back side of light guide
4c Light guide incident end face
4d thin plate
5 Lower diffusion sheet
7 Upper diffusion sheet
10 Lighting device for liquid crystal display
11 Back polarizing plate
12 Lower glass substrate for LCD panel
13 Upper glass substrate for LCD panel
14 Front-side polarizing plate
15 LCD panel black matrix
31 Back side housing
32 Inner housing for lighting equipment
33 Front case
50 Fluorescent tube assembly
51 Short side with ellipse processing
52 Short side without ellipse processing
53 Long side without ellipse processing
54 High voltage rubber holder
55 High voltage side electrode
56 Solder of high voltage side electrode
57 High voltage side harness
58 Low voltage side electrode
59 Low voltage rubber holder
60 Solder of low voltage side electrode
61 Low-voltage side harness
A Effective display area of LCD panel
a Boundary surface of the effective display area A of the liquid crystal panel
b Outer end of overlapping portion (end surface of thin plate portion 4d)
c Oblique viewing angle direction
d Angle between the boundary surface a of the effective display area A of the liquid crystal panel and the oblique viewing angle direction line c
A thin plate portion protruding from the end surface on the surface side is provided, and the light guide body that propagates the light incident from the end surface and emits it from the surface is configured to have a different thickness via the step portion, and the thickness thin side and the light scattering plate member which thin plate portion is arranged so as to overlap on the surface of, provided near the back surface and the end face of the light scattering plate member, the rear surface and the of the light scattering plate member having A linear light source that emits light to the end face;
The end face position of the thin plate portion is provided outside the effective display area of the liquid crystal panel ,
The linear light source is a fluorescent tube having at least one side portion having one or more bent portions and processed into an elliptical cross section,
The at least one side is configured such that the light emitting surface of the linear light source with respect to the end surface of the light guide is larger in area than the light emitting surface side of the linear light source with respect to the light scattering plate member. Lighting device for liquid crystal display.
The thin plate portion of the light guide protrudes from the end surface with the surface width in a state flush with the surface, and the light scattering plate member is flush with the surface on the thick side and the surface of the thin plate portion. The illumination device for liquid crystal display according to claim 1, which overlaps in a state.
The linear light source is a liquid crystal display lighting system according to claim 1, wherein the oval cross section.
The linear light source, a liquid crystal display lighting system as claimed in claim 1, wherein the long axis direction perpendicular direction to the end face of the light guide of the elliptical cross-sectional shape is arranged substantially so as to perpendicular.
LCD lighting apparatus according to claim 1, wherein one side portion which is processed in the elliptical cross-sectional shape is provided on the high voltage side.
The linear light source, a liquid crystal display lighting system as claimed in claim 1, wherein a portion other than the electrode portions having the elliptical cross section processing unit.
Minor axis / Nagajikuhi liquid crystal display lighting system as claimed in claim 1, wherein less than 0.6 to 1.0 of the elliptical cross section.
The photoelectric characteristics of the fluorescent tube having an elliptical cross section are as follows. The rate of increase in lighting start voltage exceeds 0% and within 15%, and the rate of increase in drive voltage exceeds 0% and within 10%, compared to that before the elliptical processing. 8. The illumination device for a liquid crystal display device according to claim 7 , wherein a change rate of the tube surface luminance is within ± 15%.
The lighting device for liquid crystal display according to claim 1, wherein an end surface of the light scattering plate member on the light guide body side is provided on an inner side than an end surface of the light guide body.
The illumination device for liquid crystal display according to claim 1, wherein an optical sheet in which a low turbidity diffusion sheet and a high turbidity diffusion sheet are combined is provided on the surface of the light guide.
The illumination device for liquid crystal display according to claim 1, wherein an optical sheet in which a polarization selective reflection sheet and a high turbidity diffusion sheet are combined is provided on the surface of the light guide.
A reflection sheet is provided on the back surface side of the light guide, and a fixing auxiliary material is provided on the back surface side of the reflection sheet below the end surface of the light guide, whereby the surface of the reflection sheet and the light guide The lighting device for liquid crystal display according to claim 1, wherein the rear surface is in contact with a lower portion of the end surface of the light guide.
The illumination device for liquid crystal display according to any one of claims 1 to 12 , and the illumination device for liquid crystal display disposed on the illumination device for liquid crystal display, and display is performed by transmission and non-transmission of light emitted from the illumination device for liquid crystal display. A liquid crystal display device comprising a transmissive liquid crystal panel.
The illumination device for liquid crystal display according to any one of claims 1 to 12 and the illumination device for liquid crystal display, which is disposed on the illumination device for liquid crystal display, is irradiated with light from the illumination device for liquid crystal display, and is displayed by transmission and transmission and non-transmission. A liquid crystal display device comprising: a transmission type liquid crystal panel with a reflection function that is displayed and also displayed by reflection of light from outside.
JP2003097360A 2003-03-31 2003-03-31 Liquid crystal display lighting device and liquid crystal display device Expired - Fee Related JP4255302B2 (en)
JP2003097360A JP4255302B2 (en) 2003-03-31 2003-03-31 Liquid crystal display lighting device and liquid crystal display device
DE200410015557 DE102004015557A1 (en) 2003-03-31 2004-03-30 Lighting device and liquid crystal display device
TW93108970A TWI245865B (en) 2003-03-31 2004-03-31 Illumination device and liquid crystal display apparatus
CNA2004100352242A CN1540415A (en) 2003-03-31 2004-03-31 Lighting device and LCD device
US10/813,434 US20040213018A1 (en) 2003-03-31 2004-03-31 Illumination device and liquid crystal display apparatus
KR1020040022114A KR100642672B1 (en) 2003-03-31 2004-03-31 Illumination device and liquid crystal display apparatus
JP2004303657A JP2004303657A (en) 2004-10-28
JP4255302B2 true JP4255302B2 (en) 2009-04-15
ID=33127548
JP2003097360A Expired - Fee Related JP4255302B2 (en) 2003-03-31 2003-03-31 Liquid crystal display lighting device and liquid crystal display device
US (1) US20040213018A1 (en)
JP (1) JP4255302B2 (en)
KR (1) KR100642672B1 (en)
CN (1) CN1540415A (en)
DE (1) DE102004015557A1 (en)
TW (1) TWI245865B (en)
JP4719486B2 (en) * 2004-10-01 2011-07-06 三星電子株式会社Ｓａｍｓｕｎｇ Ｅｌｅｃｔｒｏｎｉｃｓ Ｃｏ．，Ｌｔｄ． Backlight assembly and display device having the same
TWI399590B (en) * 2006-11-14 2013-06-21 Au Optronics Corp Liquid crystal display, backlight module thereof and light guide structure thereof
JP5284489B2 (en) 2009-12-28 2013-09-11 シャープ株式会社 Planar illumination device and display device including the same
JPH095742A (en) * 1995-06-23 1997-01-10 Hayashi Telempu Co Ltd Surface light source device
JPH1172626A (en) 1997-06-30 1999-03-16 Toshiba Lighting & Technol Corp Back light and liquid crystal display device using the same
2003-03-31 JP JP2003097360A patent/JP4255302B2/en not_active Expired - Fee Related
2004-03-30 DE DE200410015557 patent/DE102004015557A1/en not_active Ceased
2004-03-31 TW TW93108970A patent/TWI245865B/en not_active IP Right Cessation
2004-03-31 KR KR1020040022114A patent/KR100642672B1/en not_active IP Right Cessation
2004-03-31 CN CNA2004100352242A patent/CN1540415A/en not_active Application Discontinuation
2004-03-31 US US10/813,434 patent/US20040213018A1/en not_active Abandoned
JP2004303657A (en) 2004-10-28
CN1540415A (en) 2004-10-27
DE102004015557A1 (en) 2004-11-04
KR20040088361A (en) 2004-10-16
TWI245865B (en) 2005-12-21
KR100642672B1 (en) 2006-11-10
US20040213018A1 (en) 2004-10-28
TW200523502A (en) 2005-07-16
JP4371687B2 (en) 2009-11-25 Backlight device and liquid crystal display device
CN101346581B (en) 2010-05-19 Backlight device and display using it
KR20050045602A (en) 2005-05-17 Back light assembly of liquid crystal display