CN1763607A - Backlight lamp device and liquid crystal display device - Google Patents

Abstract

A thin liquid crystal display device and a backlight device. The backlight unit (14) has a diffuser sheet (36) for diffusing light and a light source unit (40) arranged behind the diffuser plate, and the diffuser plate diffuses light emitted from the light source unit to obtain surface emission. The light source unit has a plurality of light emitting units (50) arranged along a plane parallel to the diffusion plate. The plurality of light-emitting parts respectively include: a base material (66) made of a light-transmitting material having an emission surface (68) opposite to the diffusion plate; a light-emitting element (72) embedded in the base material; The reflective surface (77) and the reflective part (70) that guide the light from the entire area or approximately the entire area of the above-mentioned emitting surface to the diffusion member vertically or approximately vertically.

Description

Backlight device and liquid crystal display device

technical field

The present invention relates to a backlight device used in a liquid crystal display device and a liquid crystal display device having the backlight device.

Background technique

A liquid crystal display device used as a display device of a computer requires a lighting device called a backlight device because liquid crystal itself is non-luminescent. As a light source of such a backlight device, a small-diameter fluorescent tube such as a cold cathode tube is generally used at present. As a method of arranging cold cathode tubes, there are known an edge light method in which fluorescent tubes are arranged along the edge of a liquid crystal panel and a direct method in which a plurality of fluorescent tubes are arranged behind a liquid crystal panel (see Patent Document 1). Comparing these two methods, the directly below method has higher light utilization efficiency than the edge light method because the light emitted from the fluorescent tube is directly emitted without passing through a light guide plate or the like. Therefore, the directly below method is suitable for applications such as television monitors that require high brightness.

Patent Document 1: JP-A-2004-186080

Specifically, a conventional backlight device employing the direct-under method will be briefly described with reference to FIGS. 9 and 10 . As shown in the figure, the backlight unit 112 disposed behind the liquid crystal panel 110 has a quadrangular front frame 114 . A light-transmitting portion 116 in which a plurality of light-transmitting plates are stacked is housed inside the front frame 114 . In the illustrated conventional example, the light-transmitting section 116 has four light-transmitting plates, ie, a polarizing plate 118 , a front diffusing plate 120 , a rear diffusing plate 122 , and a diffusing plate 124 , arranged in order from the liquid crystal panel side. A rear frame 126 is disposed behind the light-transmitting portion. The rear frame 126 is formed with a quadrilateral base 128 that bends a plate and is separated from the light-transmitting portion 116 by a predetermined distance, and a supporting portion 130 that bends upward from opposite sides of the base 128, and is arranged and fixed on the inside of the front frame 114. So that the two supporting parts 130 support the light-transmitting part 116 . A plurality of cold cathode tubes (fluorescent tubes) 134 are arranged in parallel in a space 132 formed inside the rear frame 126 . These cold-cathode tubes 134 are held at predetermined positions by two support stands 134 , and both ends thereof are supported by lamp support stands 138 . In addition, the base portion 128 supports a plurality of partition pins 140 arranged at predetermined intervals, and the upper end of each partition pin 140 contacts the light-transmitting portion 116 to prevent the light-transmitting portion 116 from bending. A cold-cathode tube lighting inverter 142 is arranged behind the rear frame 126 , and a plurality of cold-cathode tubes 134 are connected to the inverter 142 .

According to the backlight unit 112 configured in this way, the plurality of cold cathode tubes 134 are made to emit light by supplying electric power from the inverter 142 . Of the light emitted from the cold cathode tube 134 , the light traveling from the cold cathode tube 134 toward the light transmitting portion 116 (light traveling upward in the figure) directly enters the light transmitting portion 116 . In addition, the light traveling from the cold cathode tube 134 to the rear frame 126 (the light traveling downward and laterally in the figure) is reflected by the rear frame 126 or emitted by the adjacent cold cathode tube 134 , and then enters the light transmitting part 116 . The light reaching the light transmitting portion 116 is diffused by the diffusion plate 124 and the diffusion sheets 120 and 122 . At this time, the diffusion plate 124 expands the viewing angle of light incident therein. In addition, the diffusers 120, 122 narrow the enlarged viewing angle. Therefore, the light emitted from the final diffusion sheet 120 is called high-brightness uniform surface emission. Finally, the light emitted from the diffusion sheet 120 enters the polarizing sheet 118 , where it is polarized in a predetermined direction and enters the liquid crystal panel 110 .

However, the above-mentioned backlight unit 112 uses the cold cathode tube 134 as a light source. The cold cathode tube 134 emits light in all directions on the cross section. Therefore, in order to recover and effectively utilize the light emitted from the cold-cathode tubes 134 to the rear frame 126, a predetermined interval is provided between the cold-cathode tubes 134 and the rear frame 126 arranged behind them, and adjacent cold-cathode tubes 134 A certain degree of large gap is provided between them, so that the light entering the rear frame 126 from the cold cathode tubes 134 needs to be reflected and sent to the liquid crystal panel 110 through the gap between adjacent cold cathode tubes 134 . Therefore, the dimension in the direction perpendicular to the light-transmitting portion 116 increases, which becomes a problem in downsizing the liquid crystal display device. In addition, since the cold cathode tubes 134 are arranged at predetermined intervals, the amount of light incident on the translucent portion region directly above the cold cathode tubes 134 is greater than the amount of light incident on the translucent portion region opposite to the middle region of the adjacent cold cathode tubes 134. The amount of light is large, which causes uneven brightness of an image displayed on the liquid crystal panel 110 . Therefore, in order to eliminate the brightness unevenness of the image displayed on the liquid crystal panel, it is necessary to provide a plurality of diffusing members (diffusing plate 124 , diffusing sheets 120 , 122 ) on light transmitting portion 116 as described above.

In addition, the cold cathode tube 134 has a disadvantage of inferior color reproducibility compared with a Braun tube. In order to solve this problem, it is considered to use semiconductor light-emitting liquid crystals, that is, light-emitting diodes, as the light source of the backlight. However, in order to reproduce color images, three kinds of light-emitting diodes that generate red, blue, and green light have to be provided. In this case, in order to sufficiently mix the colors of the lights emitted from the three LEDs to generate white light, it is necessary to ensure a sufficiently large distance between the LEDs and the liquid crystal panel, and thus, the thickness of the backlight device increases.

Contents of the invention

Therefore, an object of the present invention is to provide a small backlight device and a liquid crystal display device by using other light sources instead of cold cathode tubes.

To achieve this object, the backlight device according to the first aspect of the present invention has a sheet-shaped diffusion member for diffusing light and a light source portion arranged behind the diffusion member, and the light emitted from the light source portion is diffused by the diffusion member. Surface emission is obtained, and it is characterized in that the above-mentioned light source part has a plurality of light-emitting parts arranged along a plane parallel to the above-mentioned diffusion member, and each of the above-mentioned plurality of light-emitting parts includes: A base material made of a material; a light-emitting element embedded in the base material; and a light guide that guides light generated by the light-emitting element vertically or approximately vertically from the entire area or substantially the entire area of the emitting surface to the diffusion member.

In the backlight unit according to the second aspect of the present invention, the emitting surface of the light emitting unit has a rectangular planar shape.

In the backlight unit according to the third aspect of the present invention, the light guide portion has a reflection portion that reflects light emitted from the light emitting element and guides it vertically or substantially vertically toward the diffusion member.

In the backlight device according to the fourth aspect of the present invention, the light guiding portion includes: a first surface portion formed on the emitting surface, and directly injects the first light emitted from the light emitting element at an incident angle smaller than the critical angle. , and emit the first light directly incident at an incident angle smaller than the above-mentioned critical angle to the above-mentioned diffusion member vertically or approximately vertically; the second surface part, which is formed on the above-mentioned emitting surface, emits the first light emitted from the above-mentioned light-emitting element The second light is directly incident at an incident angle greater than or equal to the critical angle, and at the same time, the second light incident at an incident angle greater than or equal to the above-mentioned critical angle is reflected to the inside; the reflection part, which is formed on the surface of the above-mentioned substrate, will be formed by The second light reflected internally by the second surface portion is reflected and enters the second surface portion at an incident angle smaller than the critical angle, and then is emitted from the second surface portion toward the diffusion member vertically or substantially vertically.

In the backlight device according to the fifth aspect of the present invention, a gap is formed between at least two adjacent light emitting parts among the plurality of light emitting parts, and a device extending from the light emitting part toward the diffusion member is arranged on the gap. Pins that support the above-mentioned diffuser.

In the backlight device according to the sixth aspect of the present invention, the light source unit has a plurality of light emitting unit mounting boards arranged in parallel with the diffusion member, and the light emitting units are arranged on the light emitting unit mounting board in the first direction and along the plane along the plane. In the second direction orthogonal to the first direction.

In the backlight device according to the seventh aspect of the present invention, the plurality of light emitting units arranged in the first direction on the light emitting unit mounting substrate are connected to one corresponding light quantity adjusting unit.

In the backlight unit according to the eighth aspect of the present invention, the light emitting element has three light emitting sources emitting red, green, and blue light.

A liquid crystal display device according to the present invention is characterized by comprising the backlight device described in any one of the above aspects and a liquid crystal panel on which light emitted from the diffusion member of the backlight device is projected.

According to the backlight device of the first aspect, the light generated by the light emitting element is guided perpendicularly or substantially perpendicularly to the diffusion member from the entire region or substantially the entire region of the emission surface of the light emitting unit. Therefore, the backlight device using the tubular cold-cathode tube needs to form a space behind the cold-cathode tube in order to effectively use the light emitted from the cold-cathode tube in all directions. Therefore, the thickness of the backlight device increases. However, in the backlight device of the present invention, since there is no need to provide such a space behind the light emitting part, the overall thickness can be reduced to achieve miniaturization.

In the backlight device of the second aspect, since the emission surface of the light emitting part has a rectangular shape, a plurality of light emitting parts and the diffusion member can be arranged in parallel without gaps or substantially without gaps, and planar light beams traveling toward the diffusion member can be obtained.

The backlight device according to the third aspect can effectively utilize the light emitted from the light emitting element because it reflects the light emitted obliquely or laterally from the light emitting element and guides it vertically or substantially vertically toward the diffusion member.

In the backlight device of the fourth direction, since the light incident from the light-emitting element obliquely at an angle greater than the critical angle to the emission surface is reflected by the emission surface and the reflection part, and then guided vertically or substantially vertically from the emission surface to the diffusion member, The light emitted from the light emitting element can be effectively utilized.

In the backlight device according to the fifth aspect, since the diffusion member is supported by the pins disposed between adjacent light emitting parts, uniform surface light emission can be obtained without bending of the diffusion member.

In the backlight device according to the sixth aspect, since each light emitting unit mounting substrate is taken out together with a plurality of light emitting units supported thereon, assembly and maintenance are easy.

In the backlight device of the seventh aspect, since the plurality of light emitting units arranged along the first direction among the plurality of light emitting units mounted on the respective light emitting unit mounting substrates are connected to one light quantity adjusting unit, it is possible to adjust the light quantity of the plurality of light emitting units. It is adjusted by one light quantity adjustment unit as a unit.

In the backlight device of the eighth aspect, since the light-emitting element has red, green, and blue light-emitting sources, white light obtained by mixing these three colors can be supplied to a liquid crystal display device having the backlight device.

The liquid crystal display device of the present invention imparts the advantages of the backlight device of the above aspects.

Description of drawings

1 is a cross-sectional view of a liquid crystal display device and a backlight device of the present invention;

FIG. 2 is an exploded perspective view of the backlight device shown in FIG. 1;

Fig. 3 (a) is the plan view of light source part, (b) is its sectional view;

Fig. 4 (a) is the plan view of light source unit, (b) is its left side view, (c) is its right side view, (d) is its front view;

Fig. 5 is an enlarged cross-sectional view of a light emitting part;

FIG. 6 is a diagram showing a path of light emitted from a light emitting unit;

Fig. 7 is a circuit diagram of an output adjustment circuit;

Fig. 8 is a circuit diagram of a color adjustment circuit;

9 is a sectional view of a conventional liquid crystal display device and a backlight device;

FIG. 10 is an exploded perspective view of the backlight unit shown in FIG. 9 .

Symbol Description

10: Liquid crystal display device, 12: Liquid crystal panel, 14: Backlight device, 16: Frame, 18: Front frame, 20: Rear frame, 22: Horizontal frame, 24: Flange, 26: Opening, 28: Bottom, 30: Side wall, 32: Space, 34: Transparent plate, 36: Diffusion plate, 38: Polarizing plate, 40: Light source part, 42: Light emitting part mounting board, 44: Base plate part, 46: Leg part, 48: Fixing part, 50: light emitting part, 52: light source unit, 54: gap, 56: ventilation window, 60: spacer pin, 62: through hole, 64: cover layer, 66: transparent base material, 68: output surface, 70 : Reflecting part, 72: Light emitting element, 74R, 74G, 74B: Light emitting source, 75: Support part, 76: Substrate part, 77: Reflecting surface, 78: First surface part, 80: First light, 82: Second Surface part, 84: Second light, 86: Light emission control part, 88: Color adjustment part, 90: Offset adjustment circuit, 92: DC/DC converter, 93: Power supply, 94: Output adjustment circuit, 96: Duty ratio Control circuit, 98: RGB duty ratio control circuit, 100: Color adjustment circuit, 102R, 102G, 102B: Transistor, 104R, 104G, 104B: Variable resistor, 110: LCD panel, 112: Backlight device, 114: Front frame, 116: light transmission part, 118: polarizer, 120: front diffuser, 122: rear diffuser, 124: diffuser, 126: rear frame, 128: base, 130: support, 132: space, 134: cold cathode tube, 136: supporting platform, 138: lamp supporting platform, 140: spacer pin, 142: inverter

Detailed ways

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. In addition, in the following description, terms indicating a predetermined direction (such as "up", "down", "right", "left") and other terms containing these terms (such as "above", "below" , "right side", "left side"), however, these terms are for easy understanding of the present invention with reference to the drawings, and the technical scope of the invention is not limited by these terms. Therefore, the embodiment of the present invention described below is turned upside down, or rotated to a predetermined angle (eg, 90 degrees) in any direction (eg, clockwise or counterclockwise) also falls within the technical scope of the present invention.

1 is a cross-sectional view of a liquid crystal display device. The illustrated liquid crystal display device 10 includes a liquid crystal panel 12 and a backlight device 14 disposed behind the liquid crystal panel 12 . As the liquid crystal panel 12 , all conventionally known liquid crystal panels can be used, and the liquid crystal display device of the present invention is not limited by the type of liquid crystal and the panel structure.

The backlight unit 14 has a box-shaped housing 16 . As shown in FIG. 2 , the frame body 16 roughly includes a front frame 18 disposed adjacent to the liquid crystal panel 12 and a rear frame 20 inserted inside the front frame 18 . The front frame 18 has a rectangular horizontal frame 22 and a flange portion 24 protruding inward from an edge portion (the upper end edge portion in the figure) of the horizontal frame 22 facing the liquid crystal panel 12 . An opening 26 serving as a surface emission region. The rear frame 20 is formed in a box shape with an open area (upper area) facing the liquid crystal panel 12, has a quadrangular bottom 28 facing the opening 26 of the front frame 18 at a predetermined distance, and extends upward from the periphery of the bottom 28 toward the liquid crystal panel 12. The side wall 30 extending in the opposite direction forms a rectangular space 32 inside the rear frame 20 for accommodating a light source unit described later.

Inside the space 32 , a plurality of light-transmitting plates larger than the opening 26 are stacked and arranged near the opening 26 . In the embodiment, the plurality of light-transmitting plates include a self-supporting transparent plate (support plate) 34 made of a hard transparent material and a soft sheet that diffuses incident light in order from the bottom of the rear frame 20 toward the liquid crystal panel 12. A diffuser (diffuser) 36 and a polarizing plate 38 that transmits only light components that vibrate in a specific direction in incident light are, as shown in FIG. The side wall 30 is clamped and held.

The light source unit 40 is arranged at the bottom of the space 32 . The light source unit 40 has a plurality of light emitting unit mounting substrates 42 supporting a plurality of light emitting units described later. In the embodiment, the plurality of light emitting unit mounting bases 42 are laid over substantially the entire area in the space 32 along a plane parallel to the liquid crystal panel 12 and the opening 26 . Each light-emitting part mounting base 42 is shown in detail in FIG. 4 , and is formed by bending a plate, and includes a rectangular bottom plate 44 having one side (long side) approximately the same length as the short side of the rectangular space 32 . and one side (short side) of the length that equally divides the length of the long side direction of the rectangular space 32; the leg portion 46 is formed by bending part of the two short sides of the bottom plate portion 44 downward; the fixing portion 48 is formed by The bottom plate portion 44 is formed by bending the remaining portions of both short sides upward.

A light source unit 52 is formed by arranging a plurality of light emitting units 50 in a grid pattern on each light emitting unit mounting substrate 42 . As will be described in detail later, each light-emitting portion 50 has a quadrangular plate-shaped appearance, and no gap is provided between adjacent light-emitting portions 50 over the entire or substantially entire surface of the bottom plate portion 44 , or there is no gap between adjacent light-emitting portions 50 . There is a slight gap between them (for example, the gap is less than or equal to about 5mm, ideally less than or equal to about 2mm, preferably less than or equal to about 1mm) and fixed. The method of fixing the light emitting unit 50 is arbitrary, and for example, screws, adhesives, and double-sided adhesives can be used. For example, when the light emitting section 50 has a planar dimension of 30 mm in length and width, it is arranged with a gap of about 1 mm between adjacent light emitting sections 50 . In addition, for example, in the case of a 30-inch type backlight device, three light emitting units 50 having a planar size of 30 mm in length and width are arranged side by side in the short side direction (first direction) of the bottom plate on each light emitting unit mounting substrate 42 . Thirteen are arranged side by side in a direction (second direction) perpendicular to this direction. In this way, the seven light emitting unit mounting substrates 42 on which the light emitting unit 50 is mounted are arranged in a plane as shown in FIG. 3 to form a surface light emitting source.

The plurality of light source units 52 arranged in the space 32 are detachably connected and fixed to the side wall 30 of the rear frame 20 by the fixing part 48 of each light emitting part mounting substrate 42 with screws or the like. In addition, between the light source unit 52 and the rear frame bottom 28 , a gap 54 having a predetermined thickness is formed due to the presence of the leg portion 46 . This gap 54 is used not only as a space for wiring, but also as a connection to the outside air through a ventilation window (opening for ventilation/heat dissipation) 56 (refer to FIG. 1 ) formed on the bottom of the rear frame 28. A space where the heat generated by the light emitting unit 50 is discharged.

Returning to FIG. 1, in this embodiment, in order to support the three light-transmitting plates (transparent plate 34, diffusion sheet 36, and polarizing plate 38) from behind and prevent them from bending, a plurality of spacer pins 60 are arranged inside the space 32. . The spacer pin 60 is composed of a disc-shaped base and a tapered shaft protruding upward from the center of the base. In the through-hole 62 in the mounting base 42 , in this state, the upper end of the shaft supports the light-transmitting plate. As shown in FIG. 3 , the plurality of spacer pins 60 are preferably arranged at the center of each area that divides the light emitting unit 50 into four. However, when the opening 26 is small or the rigidity of the light-transmitting plate 34 is high, and no bending occurs on the light-transmitting plate, or if it does not pose a problem even if, for example, bending occurs, it is not necessary to arrange spacer pins. 60.

As shown in FIGS. 5 and 6 , the light emitting unit 50 has a square planar plate appearance and has a square surface facing the liquid crystal panel 12 . This surface is formed by a cover layer 64 made of a transparent plate having a substantially constant thickness. A transparent base material 66 having a dish-shaped bottom surface curved downward is schematically provided integrally under the cover layer 64 . The transparent substrate 66 is integrally formed of transparent resin, the surface of the cover layer 64 in contact with the transparent member forms the output surface 68 , and the bottom surface of the transparent substrate 66 supports a reflector (light guide) 70 with high reflectivity. The reflective portion 70 is formed, for example, by vapor-depositing metal on the bottom surface of the transparent substrate 66 . A light emitting element 72 is buried near the center bottom of the transparent base material 66 . In this embodiment, the light-emitting element 72 has three light-emitting sources (red diodes, green diodes, and blue diodes) 74R, 74G, and 74B that emit red, green, and blue light. blue light. A supporting portion 75 for supporting the transparent base material 66 is provided on the back of the reflecting portion 70 . The supporting portion 75 can be formed by resin molding on the back of the reflecting portion 70 . In addition, a substrate portion 76 is disposed behind the support portion 75 .

The bottom surface of the transparent substrate 66 forms a plurality of reflective surfaces 77 concentrically arranged with respect to the center of the light emitting unit 50, and the reflective units 70 are arranged along the reflective surfaces 77, so that all the light emitted from the light emitting element 72 is perpendicular to the liquid crystal panel 12 or Shoots roughly vertically. Specifically, if the progress of light is specifically described, as shown in FIG. The incident first light 80 is emitted vertically or substantially vertically toward the light transmitting portion and the liquid crystal panel 12 . In addition, among the light emitted from the light emitting element 72 , the second light 84 entering the second surface portion (light guide portion) 82 of the emission surface 68 at an incident angle greater than or equal to the critical angle is internally reflected by the emission surface 68 . The internally reflected second light 84 is reflected by the reflective surface 77 (precisely the reflective portion 70 ), and is then incident on the exit surface 68 again at an incident angle smaller than the critical angle, from the second surface portion 82 of the exit surface 68 toward The light-transmitting portion and the liquid crystal panel 12 emit light perpendicularly or substantially perpendicularly thereto. Also, as in the embodiment, a device having light sources 74R, 74G, and 74B that generate light of three colors can appropriately mix the three lights reflected by the emission surface 68 and the reflector 70 into completely white light. The shape of the reflective surface 77 is determined to ensure such light travel.

With such a configuration, the plurality of light emitting units 50 planarly arranged inside the rear frame 20 constitute a surface light source that emits light beams traveling vertically or substantially vertically toward the diffusion sheet 36 and the liquid crystal panel 12 as a whole. After the light emitted from the surface light source passes through the transparent plate 34 and is diffused by the diffusion sheet 36, the surface light with high brightness and no brightness unevenness having only components vibrating in a specific direction by the polarizing plate 38 passes through the opening 26 to the liquid crystal panel. 12 supplies.

Therefore, according to the backlight device 14 of the embodiment, the light emitting units 50 having the quadrangular emitting surfaces 68 are arranged vertically and horizontally without gaps or with a slight gap therebetween, and all the light emitted from the respective light emitting parts 50 goes toward the diffusion sheet 36 and the liquid crystal panel 12 . Travel vertically or approximately vertically. Therefore, the light source unit 40 forms a substantially uniform surface light source, and the uniform light beam (surface light beam) emitted from the surface light source passes through the diffusion sheet 36 to obtain more uniform surface light emission.

In addition, all the light emitted from the light source part 40 travels forward (toward the direction of the diffusion sheet 36 and the liquid crystal panel 12), because it does not diffuse in all directions like a cold cathode tube, so there is no need to form a light source on the back of the light emitting part 50. The space where the light traveling backward is reflected and recovered can reduce the thickness of the backlight unit 14 as a whole. In addition, the light emitted from the light source unit 40 can be used extremely effectively.

In addition, the light emitted from the light source unit 40 enters the diffusion sheet 36 vertically or substantially vertically, unlike the light having a so-called directional component entering the diffusion sheet 36 as in a backlight device using cold cathode tubes. Therefore, the diffusion sheet 36 for diffusing the light emitted from the light source unit 40 can be omitted. In addition, even when the diffusion sheet 36 is applied, the number of sheets used can be reduced compared with a backlight device using cold-cathode tubes. A non-self-supporting diffusion sheet made of a soft material can be used as the diffusion sheet 36 . In this case, since the transparent plate 34 is significantly cheaper than the self-supporting diffusion sheet 36 made of a hard material, the cost of the backlight device can be further reduced.

In addition, since the plurality of light emitting units 50 are mounted on the plurality of light emitting unit mounting boards 42 , assembling of the light source unit 40 and replacement work when the light emitting unit fails, etc. are facilitated.

The electrical system of the backlight unit 14 will be described. As shown in FIGS. 1 and 2 , a light emission control unit 86 and a color adjustment unit 88 are provided on the back of the rear frame 20 . As shown in detail in FIG. 7 , the light-emitting sources (light-emitting diodes) 74R, 74G, and 74B of a plurality of (three in the above-described embodiment) light-emitting units 50 arranged in the first direction on each light-emitting unit mounting substrate 42 emit light for each light-emitting unit. color and connected in series. This electrical connection is made through the void 54 formed on the back of the light emitting unit mounting substrate 42 .

In the light emission control unit 86, a plurality of light emission sources 74R, 74G, and 74B connected in series are connected to one offset adjustment circuit (light amount adjustment unit) 90, and these light emission sources 74R, 74G, and 74B connected in series can be performed as a unit. Brightness adjustment. The offset adjustment circuit 90 is also connected to a power source 93 through a DC/DC converter 92 . In addition, the DC/DC converter 92 is connected to an output adjustment circuit 94 that adjusts its output. In addition, the output of the DC/DC converter 92 is connected to the RGB duty ratio adjustment circuit (デュテイ adjustment circuit) 98 through the duty ratio control circuit (デュテイ control circuit) 96, and the RGB duty ratio adjustment circuit 98 According to the set duty ratio (duty ratio range: 2 to 100%), the duty ratio control circuit 96 adjusts the output duty ratio of the DC/DC converter 92 to perform dimming of the light source unit 40 as a whole. .

The color adjustment unit 88 has the color adjustment circuit 100 shown in FIG. 8 in proportion to each light emitting element 72 . Each color adjustment circuit 100 has transistors 102R, 102G, 102B and variable resistors 104R, 104G, 104B connected to the respective light emitting sources 74R, 74G, 74B. The base currents of 102G and 102B can adjust the currents applied to the light emitting sources 74R, 74G and 74B to adjust the light emission amounts of the light emitting sources 74R, 74G and 74B. Therefore, it is possible to adjust the color tone of the light emitted from each light emitting unit 50 and each light emitting source 74R, 74G, and 74B.

In addition, the heat generated by the light emitting element 72 is radiated to the outside through the ventilation window 56 through the air gap 54 formed behind it. Therefore, the temperature characteristics of the light emitting element 72 are stabilized.

As mentioned above, the preferred embodiment of the liquid crystal display device and the backlight device of the present invention has been described, but various modifications can be made to this embodiment. For example, as shown in FIG. 1 , a highly reflective reflective layer 106 is formed on the inner surface of the rear frame 20 (in particular, the inner surface of the side wall 30 ) to effectively utilize light emitted from the light source unit 40 by reflecting it. At this time, the reflective layer 106 can be formed by adhering a reflective sheet with high reflectivity on the inner surface of the sidewall, or by coating a highly reflective paint. In addition, in the above-mentioned embodiment, three light-emitting sources (three light-emitting diodes that respectively generate red, green, and blue light) are used as the light-emitting element, but the light-emitting element may be constituted by one light-emitting source. In addition, the above description shows only one form of the light emitting unit, and various forms of the light emitting unit (light emitting light source) proposed in JP-A-2004-186092 are also applicable to the present invention.

Claims (9)

1. A backlight device, which has a sheet-shaped diffusion member for diffusing light and a light source portion disposed behind the diffusion member, and the diffusion member diffuses the light emitted from the light source portion to obtain surface emission, characterized in The above-mentioned light source part has a plurality of light-emitting parts arranged along a plane parallel to the above-mentioned diffusion member, and each of the above-mentioned plurality of light-emitting parts includes: a base material made of a light-transmitting material having an emission surface opposite to the above-mentioned diffusion member; a light-emitting element entering the inside of the substrate; and a light-guiding portion that guides light generated by the light-emitting element from the emission surface to a region of the diffusion member that faces the emission surface. 2. The backlight device according to claim 1, wherein the emitting surface of the light emitting portion has a rectangular planar shape. 3. The backlight device according to claim 1 or 2, wherein the light guiding portion has a reflecting portion that reflects the light emitted from the light emitting element and guides it to a region of the diffusion member that faces the emitting surface. . 4. The backlight device according to claim 1 or 2, wherein the above-mentioned light guiding portion comprises: The first surface part, which is formed on the above-mentioned emitting surface, directly enters the first light emitted from the above-mentioned light-emitting element at an incident angle smaller than the critical angle, and directly enters the first light incident at an incident angle smaller than the above-mentioned critical angle. The light is emitted to a region of the diffusion member opposite to the emission surface; The second surface part, which is formed on the above-mentioned emitting surface, directly enters the second light emitted from the above-mentioned light-emitting element at an incident angle greater than or equal to the critical angle, and at the same time injects the second light at an incident angle greater than or equal to the above-mentioned critical angle. The second light is reflected inwardly; a reflective part, which is formed on the surface of the base material, reflects the second light reflected inwardly by the second surface part and enters the second surface part at an incident angle smaller than the critical angle, and then, from the second surface part It emits to a region of the diffusion member facing the emission surface. 5. The backlight device according to claim 1 or 2, characterized in that a gap is formed between at least two adjacent light emitting parts among the plurality of light emitting parts, and a light source from the above-mentioned light emitting device is disposed in the gap. The portion extends in a direction toward the diffusion member and supports the pin of the diffusion member. 6. The backlight device according to claim 1 or 2, wherein the light source section has a plurality of light emitting section mounting substrates arranged in parallel with the diffusion member, and the light emitting section is arranged on the second light emitting section mounting substrate. One direction and a second direction perpendicular to the first direction along the plane. 7. The backlight device according to claim 6, wherein the plurality of light emitting units arranged in the first direction on the light emitting unit mounting substrate are connected to one corresponding light quantity adjusting unit. 8. The backlight device according to claim 1 or 2, wherein the light-emitting element has three light-emitting sources emitting red, green, and blue lights. 9. A liquid crystal display device comprising the backlight device according to any one of claims 1 to 8, and a liquid crystal panel on which light emitted from a diffusion member of the backlight device is projected.

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