JP2008077865A - Lighting system and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting system capable of improving the extraction efficiency of light, and to provide a liquid crystal display. <P>SOLUTION: This lighting system 70 includes a plurality of light-emitting element parts 76, and a first wiring 86 and a second wiring 88 connected to these light-emitting element parts 76. The plurality of light-emitting element parts 76 are dispersedly disposed. The first wiring 86 and the second wiring 88 consist of a translucent material and have patterns that extend parallel to each other. The lighting system 70 can form the liquid crystal display, together with reflection-type or semi-transmission type liquid crystal panels disposed facing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  Some reflective liquid crystal display devices include a front light device that illuminates a liquid crystal panel from the front surface for use in an environment where external light is insufficient.

  As a front light device, there is a device that transmits light from a light source disposed beside a liquid crystal panel to a light guide plate disposed on the front surface of the liquid crystal panel and refracts the light from a groove provided in the light guide plate to guide the liquid crystal panel. In this front light device, the light introduced into the light guide plate may be refracted to the liquid crystal panel side by the groove and refracted in the reverse direction, that is, the observer side. In this case, the light refracted in the reverse direction is observed. The contrast of the liquid crystal display device may be reduced.

  Some front light devices have organic electroluminescence (EL) elements (see Patent Documents 1 and 2). The front light device is disposed opposite to the front surface of the liquid crystal panel, and the organic EL element is patterned with a cathode or the like so as to emit light in a grid pattern, for example.

JP 2006-154402 A JP 2000-267097 A

  In the front light device, the light emitting portion and the wiring portion generally block the light reflected by the liquid crystal panel, so that the intensity of the reflected light extracted through the front light device is reduced. That is, the light emitting portion is considered to be one of the factors that reduce the light extraction efficiency.

  The objective of this invention is providing the illuminating device and liquid crystal display device which can improve the extraction efficiency of light.

  An illumination device according to the present invention includes a plurality of light emitting element units, and a first wiring and a second wiring connected to the plurality of light emitting element units, and the plurality of light emitting element units are arranged in a dispersed manner. The first wiring and the second wiring have a pattern made of a light-transmitting material and extending in parallel with each other.

  The first wiring and the second wiring are preferably arranged in the same layer.

  Preferably, each of the plurality of light emitting element portions includes an organic electroluminescence element having a light emitting layer, and the light emitting layer faces the first wiring while not facing the second wiring.

  The organic electroluminescence device further includes a cathode connected to the light emitting layer, and the cathode is made of a material different from that of the second wiring and extends toward the second wiring. It is preferable that they are connected.

  Further, it is preferable that the cathode has a light shielding property, and light from the light emitting layer is emitted through the first wiring.

  Further, it is preferable that the first wiring also serves as an anode of the organic electroluminescence element.

  The cathode preferably has a light-transmitting property, and light from the light emitting layer is preferably emitted through the cathode.

  Moreover, it is preferable that the said organic electroluminescent element further has a light shielding layer on the opposite side to the said cathode with respect to the said light emitting layer.

  In addition, the light emitting device further includes a light transmitting substrate provided on a light emitting side of the plurality of light emitting element portions, and a light transmitting layer in contact with the substrate, wherein the light transmitting layer has a refractive index substantially equal to the substrate. It is preferable to have.

  In addition, a light-transmitting counter substrate facing the substrate via the plurality of light emitting element portions is further provided, and the counter substrate is in contact with the light-transmitting layer and has a refractive index substantially equal to that of the light-transmitting layer. Is preferred.

  The liquid crystal display device according to the present invention includes the illuminating device and a reflective or transflective liquid crystal panel provided to face the illuminating device.

  In addition, it is preferable that the patterns for the first wiring and the second wiring are substantially equal to the pixel pitch of the liquid crystal panel.

  With the above structure, an illumination device and a liquid crystal display device that can improve light extraction efficiency can be provided.

  Embodiments according to the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view for explaining a liquid crystal display device 50 according to an embodiment. The liquid crystal display device 50 includes a reflective or transflective liquid crystal panel 60 and an illumination device (or illumination panel) 70 provided to face the liquid crystal panel 60. Here, the illumination device 70 is disposed on the viewer side of the liquid crystal panel 60 and is used as a front light device of the liquid crystal panel 60. Although a detailed description of the liquid crystal panel 60 is omitted, various reflective or transflective liquid crystal panels can be applied. For example, the liquid crystal panel 60 includes a polarizing plate (not shown) on the illumination device 70 side. There is also a case.

  2 and 3 are a sectional view and a plan view for explaining the lighting device 70, and FIG. 4 is a partially enlarged plan view. Moreover, sectional views taken along lines 5-5, 6-6 and 7-7 in FIG. 4 are shown in FIGS. It should be noted that some of the elements are not shown in order to avoid complexity of the drawing. For example, the wiring 88 shown in FIG. 5 is omitted in FIG. 2, and the substrates 72 and 74 shown in the sectional view of FIG. Is omitted in the plan view of FIG.

  The lighting device 70 includes a pair of light-transmitting substrates 72 and 74 that face each other. Between the pair of substrates 72 and 74, a plurality of light emitting element portions 76 and a first wiring (or a first wiring) are provided. Layer) 86, second wiring (or second wiring layer) 88, translucent layer 90, and seal 96. In order to avoid the complexity of the drawing, the light emitting element portion 76 is schematically shown by a broken line in FIG.

  In the illuminating device 70, the light emission L (see FIG. 2) from the light emitting element unit 76 is irradiated to the liquid crystal panel 60 through the translucent substrate 74 on which the light emitting element unit 76 is arranged (so-called bottom emission (bottom emission)). emission) type).

  In the lighting device 70, a plurality of light emitting element portions 76 are arranged in a distributed manner (here, a case where they are scattered in a matrix shape is illustrated), and power is supplied to these light emitting element portions 76 via wirings 86 and 88. Is done. Each light emitting element portion 76 is smaller than the pixel 62 (three pixels 62 are schematically illustrated in FIG. 1) of the liquid crystal panel 60, and thus is configured in a dot shape as compared with the entire illumination device 70. ing.

  Here, the case where each light emitting element part 76 is comprised with an organic electroluminescent (EL) element is illustrated, and the light emitting element part 76 is also called the organic EL element 76 hereafter. Each organic EL element 76 includes a light emitting layer 80 and a cathode (or cathode) 82.

  The translucent substrates 72 and 74 are made of, for example, a transparent glass plate. Here, it is assumed that the substrate 72 is positioned on the viewer side, and the substrate 74 is positioned on the liquid crystal panel 60 side facing the substrate 72 via the organic EL element 76 and the like.

  The first wiring 86 has translucency and is made of a transparent conductive material such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide). The 1st wiring 86 is arrange | positioned on the translucent board | substrate 74 (refer FIG. 5 etc.). Here, a case where the first wiring 86 has a pattern including one trunk portion 86a and a plurality of branch portions 86b branched from the trunk portion 86a to the same side and extending in parallel is illustrated (FIG. 3). reference).

  The light emitting layer 80 faces the substrate 74 through the first wiring 86 and is stacked on any branch part 86b of the first wiring 86 (see FIG. 5 and the like). A plurality of light emitting layers 80 are provided on one branch 86b (see FIG. 3 and the like). The light emitting layer 80 does not face the second wiring 88. The light emitting layer 80 has a configuration in which, for example, a hole transport layer, an organic light emitting layer, and an electron transport layer are stacked.

  The cathode 82 is stacked on the light emitting layer 80 so as to face the first wiring 86 through the light emitting layer 80 (see FIG. 5 and the like). The cathode 82 is made of, for example, aluminum (Al), magnesium-silver alloy (Mg-Ag alloy), lithium-aluminum alloy (Li-Al alloy), magnesium-indium alloy (Mg-In alloy), gold (Au). , Silver (Ag) or the like can be used. The cathode 82 is made of a material different from that of the wirings 86 and 88. The cathode 82 also functions as a light-shielding layer and prevents the emitted light L from being emitted to the translucent substrate 72 side, that is, the observer side. The cathode 82 is more preferably made of a material having a high reflectance with respect to the light emission L. In this case, the intensity (or light amount) of light emitted to the liquid crystal panel 60 side through the first wiring 86 is relatively large. can do.

  The anode of the organic EL element 76 also serves as the first wiring 86.

  On the translucent substrate 74, an insulating layer 92 constituting a part of the translucent layer 90 is disposed (see FIGS. 2 and 5). The insulating layer 92 is disposed on the substrate 74 so as to cover the first wiring 86 and is in contact with the substrate 74. 4 and the like exemplify a case where the insulating layer 92 is patterned into a plurality of portions, and each portion surrounds the light emitting layer 80 and the like without the light emitting area 80a and the adjacent portions are not in contact with each other. 2 illustrates a case where the insulating layer 92 surrounds the light emitting layer 80 and the like so as to fill the space between the adjacent light emitting layers 80 and the like. Further, the insulating layer 92 may be provided so as to cover the entire surface excluding (i) the light emitting area 80a, (ii) the contact portion between the cathode 82 and the second wiring 88, and (iii) the terminal portion. The insulating layer 92 is made of a material having a refractive index (about 1.5) substantially equal to that of the translucent substrates 72 and 74, for example, silicon oxide.

  The second wiring 88 has translucency and is made of a transparent conductive material such as ITO or IZO. The second wiring 88 may be composed of the same material as the first wiring 86 or may be composed of a different material. The 2nd wiring 88 is arrange | positioned on the board | substrate 74 (refer FIG. 5 etc.). Here, a case where the second wiring 88 has a pattern including one trunk portion 88a and a plurality of branch portions 88b branched from the trunk portion 88a to the same side and extending in parallel is illustrated (FIG. 3). Etc.). The branch portion 88b of the second wiring 88 extends in parallel with the branch portion 86b of the first wiring 86 in plan view (see FIG. 3 and the like). Here, a case where the branch portions 86b and 88b are alternately arranged is illustrated. The branch portion 88 b of the second wiring 88 extends through the vicinity of the light emitting layer 80. An insulating layer 92 is interposed between the branch portions 86b and 88b (see FIG. 7 and the like).

  The second wiring 88 is connected to the cathode 82. Specifically, the cathode 82 faces the light emitting layer 80, extends on the insulating layer 92 toward the branch portion 88b of the second wiring 88, and is in contact with the branch portion 88b.

  As a result, the cathode of the power source is connected to the second wiring 88 and the anode of the power source is connected to the first wiring 86, whereby electric power is supplied to the organic EL element 76 (see FIG. 3).

  The translucent layer 90 includes the insulating layer 92 and the insulating layer 94 (see FIG. 2). The insulating layer 94 is provided in contact with the organic EL element 76, the wirings 86 and 88, and the insulating layer 92, and is filled between the substrates 72 and 74. The insulating layer 94 is in contact with at least the substrate 72, and the insulating layer 94 is also in contact with the substrate 74 when the insulating layer 92 is patterned in a plurality of portions as illustrated in FIG. In the case where the insulating layer 92 fills between the adjacent light emitting layers 80 and the like, the insulating layer 94 can be provided so as not to contact the substrate 74. The insulating layer 94 is made of a material having substantially the same refractive index (about 1.5) as the translucent substrates 72 and 74, for example, various resins such as epoxy. That is, the entire translucent layer 90 is in contact with the translucent substrates 72 and 74 and has a refractive index substantially equal to that of the substrates 72 and 74. The light transmissive layer 90 surrounds each organic EL element 76.

  The seal 96 is disposed along the peripheral edges of the substrates 72 and 74, and the substrates 72 and 74 are bonded and fixed to each other.

  Here, in the arrangement direction of the branch portions 86b and 88b of the wirings 86 and 88, the pitch 76x of the organic EL element 76 is substantially equal to the pitches 86x and 88x of the branch portions 86b and 88b, and is substantially the same as the pitch 62x of the pixels 62. Equal (see FIG. 1 and FIG. 3). In the extending direction of the branch portions 86b and 88b, the pitch 76y (see FIG. 3) of the organic EL elements 76 is substantially equal to the pitch of the pixels 62. The pitches 76x and 76y of the organic EL elements 76 may be n times or 1 / n the pitch of the pixels 62. Note that the organic EL element 76 may face any location in the pixel 62.

  The illumination device 70 is manufactured as follows, for example. First, the first wiring 86 and the second wiring 88 are patterned on the substrate 74. When both the wirings 86 and 88 are made of the same material, the wirings 86 and 88 can be formed simultaneously by patterning a single light-transmitting conductive film formed on the substrate 74. Thereafter, the insulating layer 92 is formed. Next, the light emitting layer 80 and the cathode 82 are patterned. Each element can be formed and patterned by, for example, various known methods. Next, a seal 96 is applied to the periphery of the substrate 74. Then, for example, an epoxy adhesive that constitutes the insulating layer 94 is dropped on the substrate 74 to fill the region surrounded by the seal 96. Thereafter, the substrate 72 is overlapped to cure the adhesive and the seal 96. The seal 96 may be temporarily cured before the adhesive is dropped, or the insulating layer 94 may be temporarily cured before the substrate 72 is stacked.

  The illuminating device 70 is disposed with the translucent substrate 74 facing the liquid crystal panel 60 (see FIG. 1). In this arrangement state, the light emission L from the organic EL element 76 passes through the first wiring 86 and the translucent substrate 74 and is introduced into the liquid crystal panel 60, reflected by the liquid crystal panel 60, and the translucent substrate 74. It passes through the translucent layer 90 and the translucent substrate 72 and reaches the observer.

  According to the above configuration, since the organic EL elements 76 are scattered, the aperture ratio can be increased as compared with a case where the organic EL elements 76 are extended in a lattice shape, for example. The aperture ratio can also be improved by the light-transmitting wirings 86 and 88.

  In addition, since the wirings 86 and 88 are patterned, interference due to a difference in refractive index between the wirings 86 and 88 and the translucent substrate 72 and the like can be reduced at the gap portion in the pattern. Loss can be suppressed. Further, the translucent layer 90 is in contact with the translucent substrate 74 through the gap portions of the patterns of the wirings 86 and 88, and the refractive index of the translucent layer 90 is substantially equal to the refractive index of the translucent substrate 74. Since they are equal, interference between the light-transmitting layer 90 and the light-transmitting substrate 74, that is, optical loss can be suppressed. Further, the light transmissive layer 90 is also in contact with the light transmissive substrate 72, so that optical loss due to the light transmissive layer 90 and the light transmissive substrate 72 can be suppressed.

  Therefore, according to the illumination device 70, the light extraction efficiency is improved by increasing the aperture ratio and reducing the optical loss. Here, the light extraction efficiency can be defined, for example, by the ratio of the intensity of the emitted light that finally reaches the observer with respect to the emitted intensity of the light emitting element portion.

  Further, since both the wirings 86 and 88 are arranged on the substrate 74, that is, in the same layer (same layer), they can be formed by patterning a single translucent conductive film as described above. In this case, since both wirings 86 and 88 can be formed simultaneously, the number of manufacturing steps can be reduced. Further, according to the simultaneous patterning, the alignment of the wirings 86 and 88 does not occur.

  The lattice-shaped organic EL element may be configured without patterning only the cathode in a lattice shape and patterning the light emitting layer, for example. In this case, the end of the cathode also emits light, and as a result, light leakage may occur. On the other hand, since the organic EL element 76 is patterned and the light emitting portion is completely covered with the cathode 82 which also serves as a light shielding layer, light leakage can be prevented.

  Further, as described above, the pattern pitch in the wirings 86 and 88 and the pitch of the organic EL elements 76 are substantially equal to the pitch of the pixels 62, so that moire can be suppressed.

  The bottom emission type illumination device 70 has been described above. Next, the top emission type illumination device 70B will be described with reference to the sectional view of FIG. The illumination device 70B can constitute the liquid crystal display device 50 (see FIG. 1) instead of the illumination device 70 described above. Although FIG. 8 is illustrated corresponding to FIG. 5, the illumination device 70 </ b> B is disposed with the substrate 74 illustrated above in FIG. 8 facing the liquid crystal panel 60.

  In the illumination device 70 </ b> B, the light emitting element portion 76, the first wiring 86, the second wiring 88, and the insulating layer 90 are disposed on the light transmitting substrate 72 on the viewer side. These elements 76, 86, 88, and 90 are basically configured in the same manner as in the case of the lighting device 70 except for the difference in the substrates to be arranged. In the illuminating device 70B, the light emission L from the light emitting element unit 76 is emitted to the liquid crystal panel 60 through a light transmitting substrate 74 facing the substrate 72 on which the light emitting element unit 76 is arranged (so-called top emission type).

  Here, the case where each light emitting element part 76 is comprised with an organic EL element is illustrated. In the illumination device 70B, the organic EL element 76 includes an anode (or anode) 78 and a light shielding layer 84 in addition to the light emitting layer 80 and the cathode 82 described above. The light shielding layer 84, the anode 78, the light emitting layer 80, and the cathode 82 are laminated on the branch portion 86b of the first wiring 86 in this order. The light emitting layer 80 can be configured in the same manner as the lighting device 70 described above. Alternatively, the light shielding layer 84 is formed below the first wiring 86 only in the light emitting area 80a.

  The anode 78 is connected to the light emitting layer 80. The anode 78 is made of, for example, ITO.

  In the lighting device 70B, the cathode 82 is connected to the light emitting layer 80 so as to face the anode 78 through the light emitting layer 80. The cathode 82 is made of, for example, a magnesium-silver alloy, and may be made of a lithium-aluminum alloy, a magnesium-indium alloy, aluminum, gold, silver, or the like. The cathode 82 has translucency in order to take out the light L emitted from the light emitting layer 80 through the cathode 82 and emit it to the translucent substrate 74 side, that is, the liquid crystal panel 60 side. For the cathode materials exemplified above, for example, the transmittance can be adjusted by the film thickness, and a translucent film can be formed (so-called semi-transmissive film).

  The light shielding layer 84 is disposed on the side opposite to the cathode 82 with respect to the light emitting layer 80, and the light emission L (see FIG. 2) in the light emitting layer 80 is emitted to the translucent substrate 72 side, that is, the observer side. Is prevented. The light shielding layer 84 is made of a metal material such as aluminum (Al), chromium (Cr), nickel (Ni), Mo (molybdenum), gold (Au), silver (Ag), or chromium oxide. More preferably, the light shielding layer 84 is made of a material having a high reflectance with respect to the light emission L. In this case, not only the light shielding function but also the light transmission L is reflected and the liquid crystal panel 60 side is reflected. The intensity of the light emitted to the side can be increased. According to the materials exemplified above, it is possible to realize both a light shielding function and a reflection function. The light shielding layer 84 has conductivity, and connects the anode 78 and the branch portion 86 b of the first wiring 86. That is, the light shielding layer 84 forms a part of the power supply path between the anode 78 and the first wiring 86. According to the materials exemplified above, the conductive light shielding layer 84 can be configured.

  Note that, as in the lighting device 70C shown in the cross-sectional view of FIG. 9, the light emitting layer 80 is stacked on the first wiring 86 and the first wiring 86 also serves as an anode (the above-described anode 78 can be omitted). A light shielding layer 84 may be provided between the first wiring 86 and the substrate 72 so as to face the light emitting layer 80. In this case, the light shielding layer 84 can be formed of a resin material such as a black polymer material as well as a conductive metal material.

  The other configurations of the illumination devices 70B and 70C are the same as those of the illumination device 70 described above.

  According to the illumination devices 70B and 70C, the same effect as the illumination device 70 is obtained. In the lighting device 70 described above, since the cathode 82 also serves as a light shielding layer and the first wiring 86 also serves as an anode, the number of manufacturing steps can be reduced as compared with the lighting device 70B.

  Note that the structure of the organic EL element 76 is not limited to the above example. Further, the light emitting element portion 76 can be constituted by other light emitting elements such as an inorganic EL or a light emitting diode (LED) instead of the organic EL element. Further, the shape of the wirings 86 and 88 may not be linear, and may be meandering, for example. In addition, the light emitting element portions 76 can be arranged in a delta arrangement, for example. Further, the number of the various elements, for example, the number of the light-emitting element portion 76, the branch portions 86b and 88b, the layers constituting the light-transmitting layer 90, and the like is not limited to the above example.

  Moreover, although the case where the liquid crystal panel 60 and the illuminating device 70 are in direct contact is illustrated in FIG. 1, both the 60 and 70 may be arranged apart from each other, or both the 60 and 70 may be bonded with an adhesive. It may be glued. In addition, a light-transmitting substrate (not shown) of the liquid crystal panel 60 can be used as the light-transmitting substrate 74 on the liquid crystal panel 60 side.

  Moreover, although the case where the illuminating devices 70, 70B, and 70C constitute the liquid crystal display device 50 together with the liquid crystal panel 60 is illustrated above, the liquid crystal panel 60 is only an example of an irradiation object illuminated by the illuminating devices 70, 70B, and 70C. Absent. In other words, the illumination devices 70, 70B, and 70C can be used when illuminating the document by placing it on the document, for example.

It is sectional drawing for demonstrating the liquid crystal display device which concerns on embodiment of this invention. It is sectional drawing for demonstrating the illuminating device which concerns on embodiment of this invention. It is a top view for demonstrating the illuminating device which concerns on embodiment of this invention. It is a partially expanded plan view for demonstrating the illuminating device which concerns on embodiment of this invention. It is sectional drawing in the 5-5 line in FIG. It is sectional drawing in the 6-6 line in FIG. It is sectional drawing in the 7-7 line | wire in FIG. It is sectional drawing for demonstrating the 2nd illuminating device which concerns on embodiment of this invention. It is sectional drawing for demonstrating the 3rd illuminating device which concerns on embodiment of this invention.

Explanation of symbols

  50 liquid crystal display device, 60 liquid crystal panel, 62 pixels, 62x, 76x, 76y, 86x, 88x pitch, 70, 70B, 70C illumination device, 72, 74 translucent substrate, 76 light emitting element portion, 78 anode, 80 light emitting layer , 82 cathode, 84 light shielding layer, 86 first wiring, 88 second wiring, 90 translucent layer, L light emission.

Claims (12)

A plurality of light emitting element portions;
A first wiring and a second wiring connected to the plurality of light emitting element portions;
With
The lighting device, wherein the plurality of light emitting element portions are arranged in a distributed manner, and the first wiring and the second wiring have a pattern made of a translucent material and extending in parallel to each other. The lighting device according to claim 1,
The lighting device, wherein the first wiring and the second wiring are arranged in the same layer. The lighting device according to claim 1 or 2,
Each of the plurality of light emitting element portions is composed of an organic electroluminescence element having a light emitting layer, and the light emitting layer faces the first wiring, but does not face the second wiring. The lighting device according to claim 3,
The organic electroluminescence device further includes a cathode connected to the light emitting layer, and the cathode is made of a material different from that of the second wiring, extends toward the second wiring, and is connected to the second wiring. A lighting device characterized by that. The lighting device according to claim 4,
The illuminating device, wherein the cathode has a light shielding property, and light from the light emitting layer is emitted through the first wiring. The lighting device according to claim 5,
The lighting device according to claim 1, wherein the first wiring also serves as an anode of the organic electroluminescence element. The lighting device according to claim 4,
The said cathode has translucency and the light from the said light emitting layer radiate | emits through the said cathode, The illuminating device characterized by the above-mentioned. The lighting device according to claim 7,
The organic electroluminescence device further includes a light shielding layer on the side opposite to the cathode with respect to the light emitting layer. A lighting device according to any one of claims 1 to 8,
A translucent substrate provided on the light emitting side of the plurality of light emitting element portions;
A translucent layer in contact with the substrate;
Further comprising
The light-transmitting layer has a refractive index substantially equal to that of the substrate. The lighting device according to claim 9,
A translucent counter substrate facing the substrate via the plurality of light emitting element portions;
The lighting device, wherein the counter substrate is in contact with the light-transmitting layer and has a refractive index substantially equal to that of the light-transmitting layer. The lighting device according to any one of claims 1 to 10,
A reflective or transflective liquid crystal panel provided facing the illumination device;
A liquid crystal display device comprising: The liquid crystal display device according to claim 11,
The liquid crystal display device according to claim 1, wherein the pattern of the first wiring and the second wiring is substantially equal to a pixel pitch of the liquid crystal panel.

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