JP4525492B2 - Lighting device and liquid crystal display module - Google Patents

Description

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

  Conventionally, as a backlight of a flat panel display such as a liquid crystal display device, a light source is opposed to the end face of the light guide plate, and light emitted from the light source and incident from the opposite end face is emitted in a planar shape from one main surface of the light guide plate. A sidelight type planar illumination device is used.

A point light source such as a light-emitting diode is preferably used as a light source for the above-described planar illumination device because of its low power consumption.
JP-A-8-313902

  However, when the above-described side light type planar illumination device using a point light source is used as a backlight of a large display device, the amount of light emitted from one point light source is smaller than that of other light sources such as cold cathode tubes. It is necessary to use several point light sources. On the other hand, in order to meet the recent demand for smaller and thinner display devices, lighting devices used as backlights are required to be further reduced in size and thickness. Accordingly, when a plurality of point light sources such as light emitting diodes are installed as light sources, it is necessary to mount them at high density.

  However, in an illuminating device in which a plurality of point light sources are mounted at a high density, the temperature rise of each point light source becomes a big problem. That is, when the temperature of the point light source rises, not only its lifetime is reduced, but also the luminous efficiency is lowered. In particular, in the light emitting diode, the tendency appears more remarkably.

An object of the present invention is to provide lighting in which a plurality of point light sources are mounted at a high density to facilitate downsizing and thinning, and temperature rise of each point light source is effectively suppressed to prevent a decrease in lifetime and luminous efficiency. An apparatus and a liquid crystal display module are provided.

In the lighting device of the present invention, a plurality of point light sources, a current-carrying wiring pattern and a first heat-transfer wiring pattern are collectively formed on the surface with the same material, and the plurality of point light sources are electrically connected to the current-carrying wiring pattern. A first heat transfer member that is disposed in contact with the installed drive circuit board and the first heat transfer wiring pattern and conducts heat generated by the plurality of point light sources to a first predetermined portion. It is characterized by having.
The liquid crystal display module of the present invention is a liquid crystal display module including an illuminating device that emits light toward the liquid crystal display panel, and the illuminating device includes a plurality of point light sources, an energization wiring pattern, and a first wiring pattern. The heat transfer wiring pattern is collectively formed on the surface of the same material, and the plurality of point light sources are in contact with the first heat transfer wiring pattern and the drive circuit board electrically connected to the energization wiring pattern. And a first heat transfer member that conducts heat generated by the plurality of point light sources to a first predetermined portion.

According to the present invention, despite the fact that a plurality of point light sources are mounted at a high density, the temperature rise of each point light source is effectively suppressed, and the life and luminous efficiency of the plurality of point light sources are highly maintained. In addition, a liquid crystal display module can be provided.

  FIG. 1 is a schematic cross-sectional view showing a liquid crystal display module equipped with a planar illumination device as an embodiment of the present invention, FIG. 2 is a plan view showing the planar illumination device, and FIGS. ) Is a partial cross-sectional view and a partial perspective view showing a main part Q of the surface illumination device, and (b) shows a Q1 portion in (a).

  As shown in FIG. 1, the housing of the present liquid crystal display module includes a storage case 1 having a shape obtained by removing a top plate of a flat rectangular parallelepiped box, and a cover case 2 having the same shape from which a bottom plate has been removed. Being done. Both of these cases 1 and 2 are formed by processing a metal plate. A display window 2b for observing the display is formed in the top plate 2a of the cover case 2.

  A main frame 3 is disposed in the casing. The main frame 3 of the present embodiment is formed by two spaces of a front chamber 3a and a rear chamber 3b that are both flat and substantially rectangular parallelepiped. That is, a partition shelf 3d protrudes from the side plate 3c forming a rectangular cylindrical frame at a predetermined height position over the entire inner surface of the side plate 3c, and the front chamber 3a and the rear chamber 3b are separated from each other by the partition shelf 3d as a boundary. The front chamber 3a and the rear chamber 3b are formed so as to overlap each other, and are communicated with each other by a space surrounded by a partition shelf 3d.

  A liquid crystal display panel 4 is accommodated in the front chamber 3 a of the main frame 3. The liquid crystal display panel 4 is formed by bonding a pair of glass substrates 5 and 6 on which electrodes (not shown) are formed with a predetermined gap therebetween by a frame-shaped sealing material (not shown) with the respective electrode formation surfaces facing each other. The liquid crystal (not shown) is sealed between the glass substrates 5 and 6 surrounded by the frame-shaped sealing material. A pair of front and rear polarizing plates 7 and 8 are attached to the outer surfaces of the glass substrates 5 and 6 opposite to the liquid crystal sealing side, respectively.

  The size of the pair of glass substrates 5 and 6 in the liquid crystal display panel 4 of this example is larger in the rear glass substrate 6 than in the front glass substrate 5 on the display surface side. 6 is joined in such an arrangement that one edge of the rear glass substrate 6 protrudes from a corresponding edge of the front glass substrate 5. On the protruding edge 6a of the rear glass substrate 6, wirings drawn from the respective electrodes and connection terminals (not shown) at respective ends thereof are arranged to form driving circuit portions. A driver LSI 9 as a drive circuit element is mounted on COG (Chip On Glass). A flexible printed circuit (FPC) 10 is conductively joined to the input terminal area of the drive circuit section.

  In the rear chamber 3b of the main frame 3, a sidelight type planar illumination device 11 is accommodated. The sidelight type planar illumination device 11 includes a light guide plate 12 whose outer shape forms a rectangle substantially corresponding to the liquid crystal display panel 4 to be irradiated. The light guide plate 12 is a transparent plate that emits light incident from the end surface in a planar shape from the one main surface with the end surface as a light incident surface and one of the main surfaces as a light output surface. The light guide plate 12 of the present embodiment is formed by molding using a transparent resin material such as acrylic resin, and both end surfaces 12a and 12a (see FIG. 2) in the longitudinal direction are respectively light incident surfaces, The rear surface 12c opposite to the front surface 12b is formed with a fine uneven surface so as to reflect the incident propagation light in the light guide plate 12 toward the light emitting surface (front surface) 12b.

  As shown in FIG. 2, light emitting diodes (hereinafter referred to as LED (Light-Emitting Diode)) 13 as point light sources are respectively provided along both longitudinal end surfaces (light incident surfaces) 12 a and 12 a of the light guide plate 12. In this example, twelve of them are arranged facing each other. These 12 LEDs 13 are directly mounted on PCBs (Printed-Circuit Boards) 14 and 14 at equal intervals, respectively. In the liquid crystal display module of the present embodiment, 24 LEDs 13 are output at about 0.9 W toward a display screen having a liquid crystal display panel 4 size of 6.4 inches (diagonal distance: about 163 mm). Irradiate with planar light obtained by lighting.

  As shown in FIGS. 3A and 3B, a copper pattern 14 a is formed on the PCB 14. This copper pattern 14a is a heat transfer dedicated copper pattern provided separately from the power supply wiring (not shown) for each LED 13 mounted, and the power supply copper pattern (on both sides of the PCB 14) (Not shown) are formed in the same process. The heat transfer copper patterns 14a formed on both the front and back sides of the PCB are connected in communication by a copper layer deposited on the inner surface of the through hole 14b. And in the front side copper pattern 14a, the contact part 14c wider than another part is formed between each LED13, respectively. In addition, power supply lead wires 14d and 14d (see FIG. 2) are conductively connected to each drive circuit board 14, respectively.

  Returning to FIG. 1, a light reflecting sheet 15 is mounted on the rear surface 12 b of the light guide plate 12. The light reflecting sheet 15 is provided to reflect the light emitted to the outside without being reflected by the rear surface 12b formed on the minute uneven surface, and to re-enter the light guide plate 12, whereby the LED 13 The usage efficiency of the light emitted from is greatly improved.

  As shown in FIG. 2, the light guide plate 12 having the light reflecting sheet 15 (see FIG. 1) attached to the pair of PCBs 14, 14 on which the plurality of LEDs 13 described above are mounted and the rear surface 12 c is provided inside the light frame 16. It is installed at a predetermined position. The light frame 16 serves as a second heat transfer member of the present invention, is formed by processing a sheet metal material rich in thermal conductivity, and both longitudinal end surfaces (light incident surfaces) 12a of the light guide plate 12 to be accommodated. , 12a, a pair of side plates 16a, 16a are erected vertically to the bottom plate 16b (see FIG. 1).

  The pair of PCBs 14 and 14 on which the LEDs 13 are mounted are installed in the light frame 16 while being sandwiched between the side plate 16 a and the presser plate 17. This presser plate 17 serves as a first heat transfer member of the present invention, and is formed by processing a sheet metal material rich in thermal conductivity like the light frame 16, and as shown in FIG. At one end thereof, a plurality of pressing pieces 17a having an L-shaped cross section are formed to extend in a comb shape corresponding to the gaps of the LEDs 13. Each L-shaped pressing piece 17a is in contact with the surface of the PCB 14 between the LEDs 13, and the back surface of the PCB 14 is in contact with the side plate 15a. In this case, each L-shaped pressing piece 17a is in close contact with a wide area of the contact portion 14c formed wide between the LEDs 13 in the copper pattern 14a disposed on the surface of the PCB 14. Therefore, the heat generated by the LED 13 quickly propagates to the other end of the presser plate 17 through a heat transfer path formed by bringing the copper pattern 14a having high thermal conductivity and the L-shaped pressing piece 17a into close contact with each other over a wide area. Is done.

  As shown in FIG. 1, the other end side of each presser plate 17 extends through the through hole of the main frame 3 to the outside of the main frame 3 and is bent along the outer surface of the frame side plate 3c. . These bent end portions 17b are in close contact with the inner surface of the shield case side plate 2c in a state where the shield case 2 is fitted in the storage case 1. Thereby, the heat propagated to the bent end portion 17b of each presser plate 17 is quickly dissipated to the outside of the liquid crystal display module through the shield case 2 rich in thermal conductivity.

  On the front surface 12b of the light guide plate 12, two optical sheets, a light diffusion sheet 18 and a prism sheet 19, are superposed in this order. The light diffusion sheet 18 is installed in order to make the luminance distribution of the irradiation light emitted from the light guide plate 12 planar, and the prism sheet 19 is installed to align the emission direction of the irradiation light in the front direction.

  The side light type planar lighting device 11 configured as described above is fitted and mounted to the main frame 3 so that the light frame 16 closes the bottom of the rear chamber 3b, and is stored and held at a predetermined position in the rear chamber 3b. Has been.

  In the sidelight type planar illumination device 11, light emitted from the 24 LEDs 13 enters the light guide plate 12 from its opposite end surface (light incident surface) 12a, and the incident light has minute unevenness. When incident on the formed rear surface 12b, the light is totally reflected toward the front surface (light emitting surface) 12a and emitted from the front surface 12a in a planar shape. The planar irradiation light emitted from the front surface 12a is transmitted through the light diffusion sheet 18 and the prism sheet 19, and is irradiated to the liquid crystal display panel 4 as planar light having a substantially uniform luminance distribution and high luminance in the front direction. Is done.

  On the rear side of the light frame 16, the drive control circuit board 20 is installed on the inner surface of the bottom plate 1 a in the storage case 1. The drive control circuit board 20 controls the driving of the entire liquid crystal display module. Accordingly, the flexible wiring board 10 and the LEDs 13 that are conductively bonded to the end of the glass substrate 6 of the liquid crystal display panel 4 are mounted. The lead wire 14d drawn out from the PCB 14 is conductively connected.

  Here, the heat dissipation action generated from the LED 13 in the liquid crystal display module will be described in detail.

  The heat generated by turning on the twelve LEDs 13 mounted on each PCB 14 is mainly L-shaped pressing of the presser plate 17 which is the first heat transfer member brought into contact with the copper pattern 14a on the surface. It is transmitted to the bent end portion 17b on the other end side that extends outside the main frame 3 of the presser plate 17 through the piece 17a, is transmitted to the shield case side plate 2c that is in close contact with the bent end portion 17b, and is dissipated out of the module. The The heat dissipation path through the first heat transfer member is formed by bringing copper or sheet metal material having excellent thermal conductivity into close contact with each other, and the contact area 14c having a wide contact area between the copper pattern 14a and the L-shaped pressing piece 17a. Since it is ensured largely by forming, a rapid heat dissipation effect can be produced.

  The heat generated from the LED 13 is transferred from the copper pattern 14a on the PCB to the copper pattern 14a on the back surface through the copper layer of the through hole 14b, and the heat transferred to the back surface is in close contact with the copper pattern 14a on the back surface of the PCB 14. The light is transmitted to the bottom plate 16b through the light frame side plate 16a as the second heat transfer member, and is diffused into the space in the storage case 1 from here. Since the heat dissipation path via the second heat transfer member is also formed by bringing copper or sheet metal material excellent in thermal conductivity into close contact with each other, a rapid heat dissipation effect is achieved.

  As described above, the illuminating device 11 used in the liquid crystal display module of the present embodiment has the drive circuit board 14 on which the plurality of LEDs 13 are mounted at a high density, the presser plate 17 that is the first heat transfer member, and the second heat transfer member. The heat transfer member 16 is sandwiched between the light frames 16 and the heat generated by the LEDs 13 via the heat transfer members 16 and 17 is quickly dissipated to the outside of the lighting device 11. As a result, it is possible to reduce the size and thickness of the LED 13 and to suppress the temperature rise of the individual LEDs 13 and maintain the lifetime and the luminous efficiency at a high level.

  The second heat transfer member also serves as the light frame 16 that houses and holds the light guide plate 12, thereby simplifying the structure, reducing the number of components, and driving circuit made of an expensive material having excellent thermal conductivity. Since the desired heat dissipation effect described above can be obtained without using a substrate, the cost of the lighting device is greatly reduced.

  As a result, according to the liquid crystal display module to which the illumination device of the present embodiment is applied, not only the reduction in size and thickness and the cost reduction are promoted, but also the lifetime and luminous efficiency of the illumination device as a backlight are maintained at a high level. Therefore, a sufficiently bright display can be obtained for a long time.

  Next, a modification of the above embodiment will be described with reference to FIGS. 4 (a) and 4 (b). In addition, the same code | symbol is attached | subjected about the component same as the said embodiment, and the description is abbreviate | omitted.

  This modification is intended to prevent the temperature increase of the LED 13 not only by quickly dissipating the heat generated by energizing the LED 13 but also by suppressing the increase in the ambient temperature of the LED 13. is there.

  That is, as shown in FIG. 4A, the presser plate 41 as the first heat transfer member in the present modification is for holding the drive circuit board 14 on which the LED 13 is mounted between the light frame side plate 16a. The pressing piece 41a and the engaging piece 41b for latching the edge part of the front surface 12b of the light-guide plate 12 are provided.

  The holding plate 41 is formed by processing a sheet metal material having excellent thermal conductivity, and as shown in FIG. 3B, the portion corresponding to the gap between the adjacent LEDs 13 is perpendicular to the comb teeth. The pressing piece 41a is formed by being bent, and the portion between the pressing pieces 41a is extended without being bent to form the engaging piece 41b. That is, the pressing pieces 41a and the engaging pieces 41b are alternately formed. The inner surface 41c of the engagement piece 41b facing the LED 13 is finished to a mirror surface.

  The presser plate 41 formed as described above has the pressing piece 41a in contact with the surface of the PCB 14 between the LEDs 13 to bring the back surface of the PCB 14 into close contact with the side plate 15a, and the engaging piece 41b on the light incident side end of the front surface 12b of the light guide plate 12. It is mounted on the main frame 3 in a state where it is press-fitted to the part. In this case, similarly to the above-described embodiment, the end portion of the presser plate 41 extending outside the main frame 3 is bent along the outer surface of the frame side plate 3c and is in close contact with the inner surface of the shield case side plate 2c. 41c is formed.

  In the present modified example configured as described above, the heat of each LED 13 main body is the same as that of the above-described embodiment in that the first heat dissipation path and the second heat transfer path through the presser plate 41 that is the first heat transfer member. The radiant heat from the LED 13 that is quickly dissipated through the second heat dissipation path via the light frame 16 that is a heat member and accumulates in the light guide plate 12 is the first heat dissipation via the engagement piece 41b of the presser plate 41. Dissipated through the route. Thereby, the temperature rise of each LED13 is suppressed more notably, coupled with the fact that the increase in the ambient temperature of each LED13 is effectively prevented.

  Further, since the engaging piece 41b of the presser plate 41 is press-engaged with the light incident side end portion of the front surface (light emitting surface) 12b of the light guide plate 12, light is emitted from this portion, and leakage light or stray light is generated. Problems are prevented, and the inner surface 41c of the engaging piece 41b is formed as a mirror surface. Therefore, the light emission efficiency from each LED 13 can be mirror-reflected by the inner surface 41c and the light utilization efficiency can be increased.

  As a result, the liquid crystal display module to which the illumination device of the present modification is applied not only promotes downsizing and thinning and cost reduction, but also maintains the lifetime and luminous efficiency of the illumination device as a backlight to a higher level. In addition, the occurrence of leakage light and stray light is prevented and the light use efficiency is enhanced, so that high-quality and bright display can be realized over a long period of time.

The present invention is not limited to the above embodiment.
For example, the present invention is not limited to the sidelight type planar illumination device using the light guide plate as in the illumination device of the above embodiment, but has a configuration in which a large number of LEDs are simply mounted on the PCB without using the light guide plate. The present invention can be widely applied to various other illumination devices in which a plurality of point light sources are mounted with high density on a substrate, such as a card-type illumination device that directly uses light emitted from an LED as irradiation light.

  Of course, the present invention can be applied not only to lighting devices that use LEDs as point light sources, but also to lighting devices that use other point light sources such as light bulbs.

It is typical sectional drawing which shows the liquid crystal display module to which the planar illuminating device as one Embodiment of this invention was applied. It is a top view which shows the planar illuminating device in the said liquid crystal display module. (A) is a perspective view which shows the principal part Q of the said planar illuminating device, (b) is typical sectional drawing which shows the Q1 part. (A) is a perspective view which shows the principal part in the modification of the said embodiment, (b) is typical sectional drawing which shows the press plate in it.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Storage case 2 Cover case 3 Frame 4 Liquid crystal display panel 5 and 6 Glass substrate 7 and 8 Front and back polarizing plate 9 Drive circuit element 10 Flexible wiring board 11 Planar illumination device 12 Light guide plate 13 LED (Light-Emitted Diode)
14 PCB (Printed-Circuit Board)
15 Light reflection sheet 16 Light frame 17, 41 Press plate 20 Electronic circuit board

Claims (11)

Multiple point sources,
A drive circuit board in which the energization wiring pattern and the first heat transfer wiring pattern are collectively formed on the surface of the same material, and the plurality of point light sources are conductively installed on the energization wiring pattern;
A first heat transfer member disposed to contact the first heat transfer wiring pattern and conducting heat generated by the plurality of point light sources to a first predetermined portion;
A lighting device comprising: A second heat transfer member that conducts heat generated by the plurality of point light sources to a second predetermined portion;
The drive circuit board has a second heat transfer wiring pattern formed on the back surface,
The lighting device according to claim 1, wherein the second heat transfer member is disposed so as to be in contact with the second heat transfer wiring pattern. The drive circuit board is formed with a through hole that allows communication between the front surface of the drive circuit board and the back surface of the drive circuit board.
The lighting device according to claim 2, wherein the first heat transfer wiring pattern and the second heat transfer wiring pattern are connected through a through hole.   4. The lighting device according to claim 2, wherein the drive circuit board is disposed so as to be sandwiched between the first heat transfer member and the second heat transfer member. 5. The first heat transfer wiring pattern includes a first region disposed between two adjacent point light sources and a second region covered with the point light sources, and the first region. The wiring width of the region is formed wider than the wiring width of the second region,
5. The illumination according to claim 1, wherein the first heat transfer member is disposed in contact with the first heat transfer wiring pattern in the first region. 6. apparatus. A light guide plate that allows light emitted from the plurality of point light sources to be incident from an end surface and to be emitted in a planar shape from one main surface;
5. The lighting device according to claim 2, wherein the second heat transfer member is a case member that houses the light guide plate, the plurality of point light sources, and the drive circuit board.   The lighting device according to claim 6, wherein the drive circuit board is disposed such that a surface of the drive circuit board is parallel to the end face of the light guide plate. The lighting device according to claim 2, wherein the first heat transfer member or the second heat transfer member is made of metal.   The lighting device according to claim 1, wherein the energization wiring pattern and the first heat transfer wiring pattern are made of copper.   The lighting device according to claim 1, wherein the point light source is a light emitting diode. A liquid crystal display module including an illumination device that emits light toward a liquid crystal display panel,
The lighting device includes:
Multiple point sources,
A drive circuit board in which the energization wiring pattern and the first heat transfer wiring pattern are collectively formed on the surface of the same material, and the plurality of point light sources are conductively installed on the energization wiring pattern;
A first heat transfer member disposed to contact the first heat transfer wiring pattern and conducting heat generated by the plurality of point light sources to a first predetermined portion;
A liquid crystal display module comprising:

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