JP4842390B1 - Illumination device and image display device including the same - Google Patents

Abstract

Provided are an illuminating device that uses a small number of fixing parts to improve heat dissipation performance and simplify a manufacturing process, and an image display device including the illuminating device.
The heat conductive member 6 is opposed to the light guide member 22 of the light source holding member 4 and the second plate-like portion in contact with the surface of the heat radiating member 5 facing the light guide member 22. A first plate-like portion in contact with the surface to be fixed, and a contact surface between the heat-dissipating member 5 and the second plate-like portion is fixed to strengthen the contact between the heat-radiating member 5 and the second plate-like portion A plurality of portions 50 are provided, and the fixed portions 50 are linearly arranged on a plurality of rows along the first direction on the contact surface, and are arranged on two adjacent rows among the plurality of rows. The fixed portions 50 are not arranged linearly along a second direction orthogonal to the first direction.
[Selection] Figure 1

Description

  The present invention relates to an illumination device used in an image display device such as a liquid crystal display device.

  In general, an image display device such as a liquid crystal display device includes a display panel for controlling brightness, chromaticity, and the like of a pixel, a backlight device (illumination device) that emits light toward the display panel, and these It consists of a control circuit and a circuit board for controlling.

  The backlight device diffuses light rays in the image display device and emits light toward the display panel. There are two types of backlight devices: a direct-light type in which light sources are distributed on the back side of the backlight device, and an edge light method in which the light source is installed to allow light to enter from the side of the backlight device (“side light method”). Also called). The edge light method has an advantage that the thickness of the backlight device can be reduced compared with the direct type and the commercial value can be increased.

  Conventionally, cold cathode fluorescent lamps have been used as types of light sources used in image display apparatuses. In recent years, point light sources such as light-emitting diodes (hereinafter referred to as “LEDs”) have also been used. In general, a light source generates heat together with light. Even in the case of an LED, heat is generated by causing a current to flow to emit light. When the LED becomes high temperature due to the heat, the luminous efficiency is lowered, and the lifetime of the element in the image display device is shortened. In the worst case, the element is destroyed and there is a possibility that the element does not emit light.

  In particular, in the edge light system, the light source serving as a heat source is not distributed on the back surface of the backlight device, and is installed in the edge portion around the backlight device, which is a disadvantageous configuration from the viewpoint of heat dissipation. Yes. This is because heat is most likely to be conducted and released when it has a uniform distribution, and heat and conduction are less likely to occur when it has a non-uniform distribution.

  Further, in recent years, the edge light system has been used not only on a small screen (display) such as a mobile phone but also on a large screen (display) such as a television. In order to increase the size of the screen, the luminance on the screen cannot usually be reduced. Therefore, the total amount of light required for the light source must be increased in proportion to the area. That is, it is necessary to increase the amount of light in proportion to the square of the length in the vertical direction or the horizontal direction on the screen.

  On the other hand, in the case of the edge light system, the amount of increase in the space where the light source can be installed is proportional to the length of the periphery of the screen (display). That is, only an increase proportional to the first power of the length in the vertical or horizontal direction on the screen can be obtained. Therefore, in principle, the amount of light required per LED increases, and the amount of heat generation increases.

  This situation is a general rule relating to the light source when the screen size is increased from the direct type to the edge light method. However, heat generation from the light source is larger in the light incident method from the upper and lower two sides or the left and right sides of the screen than the light incident method from the four sides of the screen. In particular, liquid crystal televisions, personal computer displays, and the like are generally used in a horizontally long shape, so that heat generation is greater when light enters from the left and right sides rather than the upper and lower sides.

  With the frequent use of the edge light system, various heat dissipating means in lighting devices have been devised so far. For example, Patent Documents 1 and 2 describe a lighting device in which components are connected to each other by screwing. In these lighting devices, an L-shaped heat conductive member is connected to the light source and the light source holding member, and heat generated by the light source is conducted to the light source holding member through the heat conductive member. Then, heat is radiated by the light source holding member.

JP 2006-267936 A (publication date: October 5, 2006) JP 2010-92670 A (publication date: April 22, 2010)

  However, the lighting devices described in Patent Documents 1 and 2 require a large number of screwing points in order to improve the heat dissipation performance, and as a result, the manufacturing process of the lighting device and the image display device including the lighting device is complicated. Has the problem.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide an illuminating device that can improve the heat dissipation performance and simplify the manufacturing process by reducing the number of fixing points, and the same. An object is to provide an image display device.

  As a result of intensive studies in view of the above problems, the present inventors can efficiently dissipate heat from the light source even in a small number of fixed locations by making a plurality of fixed locations unique. As a result, the present invention has been completed.

  That is, in order to solve the above problems, the illumination device of the present invention has a light source, a light guide member having a light incident surface and a light emitting surface perpendicular to the light incident surface, and the light source to the light incident surface. A light source holding member for directing, a heat dissipating member disposed on the back surface of the light guide member so as to face the light emitting surface and connected to the light source holding member, and the light source holding member and the heat dissipating member. A heat conductive member in contact with the member, wherein the heat conductive member is a first plate-like portion in contact with a surface of the light source holding member facing the light guide member, and the heat dissipation. The member has a second plate-like portion that contacts a surface facing the light guide member, and the light source has a first plate-like portion on the surface facing the light incident surface of the light source holding member. Disposed on the contact surface between the heat dissipation member and the second plate-like portion. There are provided a plurality of fixing parts for strengthening the contact between the material and the second plate-like part, and the fixing parts are linearly arranged on a plurality of rows along the first direction on the contact surface, The fixing portions arranged on two adjacent rows among the plurality of rows are not arranged linearly along a second direction orthogonal to the first direction.

  According to the said structure, since heat is spread | diffused by the heat conductive member, heat can be efficiently transmitted to a thermal radiation member. Thereby, in the whole said illuminating device, the heat conduction from a light source to a heat radiating member becomes favorable. As a result, the lighting device of the present invention can improve the heat dissipation performance.

  Moreover, according to the said structure, since the heat conductive member is provided separately from the light source holding member, heat dissipation performance can be improved, maintaining structural strength.

  Moreover, according to the said structure, since heat is diffused by a heat conductive member, the heat distribution in a light source becomes uniform, and the dispersion | variation in the temperature in a light source can be reduced. As a result, the illumination device of the present invention can suppress uneven brightness of the light source.

  Moreover, according to the said structure, the heat distribution in a heat radiating member becomes uniform and can further improve heat dissipation performance.

  Moreover, according to the said structure, the thermal resistance between a thermal radiation member and a 2nd plate-shaped part can be made small. As a result, heat conduction from the light source to the heat radiating member is improved, so that the heat radiating performance of the lighting device can be improved.

  In the illumination device of the present invention, the second direction may be a light incident direction from the light source to the light guide member.

  In the lighting device of the present invention, it is preferable that the fixing portion is formed by screwing.

  According to the above configuration, the contact between the heat radiating member and the second plate-shaped portion can be further strengthened, so that the thermal resistance between the heat radiating member and the second plate-shaped portion can be further reduced.

  In the illuminating device of the present invention, the number of fixing portions arranged on the row distal from the first plate-like portion is larger than the number of fixing portions arranged on the row proximal to the first plate-like portion. Preferably, the number of fixing portions arranged on the most distal row from the first plate-like portion is the largest, and the fixing portions arranged on the most proximal row from the first plate-like portion More preferably, the number of is the smallest.

  According to the above configuration, since the contact between the heat radiating member and the second plate-shaped portion can be further strengthened by increasing the number of fixed portions far from the first plate-shaped portion, the heat radiating member and the second plate-shaped portion. The thermal resistance between the two can be further reduced.

  In the illuminating device of the present invention, it is preferable that the interval between the fixed portions arranged on the rows along the first direction decreases in the first direction.

  According to the said structure, since the contact with a heat radiating member and a 2nd plate-shaped part can be further strengthened, the thermal resistance between a heat radiating member and a 2nd plate-shaped part can be made smaller.

  In the illuminating device of the present invention, it is preferable that the distance between two adjacent rows of the plurality of rows decreases in the second direction.

  According to the said structure, since the contact with a heat radiating member and a 2nd plate-shaped part can be further strengthened, the thermal resistance between a heat radiating member and a 2nd plate-shaped part can be made smaller.

  In order to solve the above problems, an image display device according to the present invention includes the illumination device according to the present invention.

  According to the above configuration, since the temperature rise of the element can be suppressed even when operated at high luminance to irradiate a large screen, it is possible to realize a large and thin image display device by side incident light. it can.

  As described above, the illuminating device of the present invention has a light source, a light guide member having a light incident surface and a light emitting surface perpendicular to the light incident surface, and the light source disposed toward the light incident surface. A light source holding member, a heat radiating member disposed on the back surface of the light guide member so as to face the light emitting surface and connected to the light source holding member, and the light source holding member and the heat radiating member in contact with each other. The heat conductive member includes a first plate-like portion that contacts a surface of the light source holding member facing the light guide member and the heat dissipation member. A second plate-like portion that is in contact with the surface facing the optical member, and the light source is disposed on the surface facing the light incident surface of the light source holding member via the first plate-like portion. The contact surface between the heat radiating member and the second plate-like portion is in contact with the heat radiating member and the second plate-like portion. A plurality of fixing portions are provided, and the fixing portions are linearly arranged on a plurality of rows along the first direction on the contact surface, and two adjacent rows among the plurality of rows. The fixed portions arranged on the top are not arranged linearly along a second direction orthogonal to the first direction.

  Therefore, the illuminating device of the present invention has an effect that it is possible to realize an illuminating device that reduces the number of fixing points and realizes improvement of heat dissipation performance and simplification of the manufacturing process, and an image display device including the same. .

It is sectional drawing which shows schematic structure of the liquid crystal display device provided with the backlight apparatus in Embodiment 1 of this invention. It is a perspective view which shows the structure of the light source vicinity of the backlight apparatus in Embodiment 1 of this invention. It is sectional drawing which shows the structure of the light source vicinity of the backlight apparatus in Embodiment 1 of this invention. It is sectional drawing which shows the structure of the light source vicinity of the conventional backlight apparatus. (A) * (b) is typical sectional drawing for demonstrating the difference in heat conductive performance in case the magnitude | size of a heat source differs. (A) * (b) is sectional drawing which shows the preferable structure of the light source vicinity of the backlight apparatus in Embodiment 1 of this invention. It is sectional drawing which shows the preferable structure of the light source vicinity of the backlight apparatus in Embodiment 1 of this invention. (A) * (b) is a schematic diagram which shows arrangement | positioning of the fixing | fixed part at the time of seeing a 2nd plate-shaped part from the light-projection surface side.

  Embodiments of the present invention will be described in detail below, but the scope of the present invention is not limited to these descriptions, and modifications other than the following examples may be made as appropriate without departing from the spirit of the present invention. It can be implemented.

(I) Configuration of Lighting Device in the Present Embodiment The lighting device of the present embodiment will be specifically described with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view illustrating a configuration of a liquid crystal display device (image display device) 10 including a backlight device (illumination device) 1 according to the present embodiment. FIG. 2 is a perspective view showing a configuration in the vicinity of the light source 7 of the backlight device 1 in the present embodiment. FIG. 3 is a cross-sectional view showing a configuration in the vicinity of the light source 7.

  As shown in FIGS. 1 to 3, the backlight device 1 according to the present embodiment mainly includes a light source 7 and a light source 7 including a plurality of point light sources (light emitting elements) 2 and a substrate 3 on which the point light sources 2 are mounted. A frame (light source holding member) 4 to be fixed, a chassis (heat radiating member) 5 connected to the frame 4, a heat conductive plate (heat conductive member) 6 disposed between the light source 7 and the frame 4, and incident from the light source 7 A light guide plate (light guide member) 22 that emits the emitted light is provided. As a means for connecting each member (component), in addition to screwing, for example, methods such as fixing with an adhesive tape, an adhesive, etc., fitting, and pressure welding are conceivable.

  As shown in FIG. 1, the liquid crystal display device 10 in this embodiment mainly includes a backlight device 1, a reflection sheet 21, an optical sheet 23, a liquid crystal panel 24, and a bezel (outer frame) 25.

  The backlight device 1 according to the present embodiment has a purpose of improving the heat conduction performance when transmitting heat generated from the light source 7 to the heat radiating member 5, in order to strengthen the contact between the heat conduction plate 6 and the chassis 5. This is realized by making the arrangement of the fixing portion 50 unique. Details of each member will be described below.

<Light source (light emitting element and substrate)>
The light source 7 used in the backlight device 1 of the present embodiment may be only the point light source (light emitting element) 2 or may be one in which the point light source 2 is carried on the substrate 3. In each drawing, the light source 7 is shown as having the point light source 2 carried on the substrate 3.

  In the backlight device 1 of the present embodiment, the light source 7 serves as a heat source, and the necessity of heat dissipation arises.

  Examples of the point light source 2 used in the backlight device 1 of the present embodiment include a light emitting diode (LED) and a cold cathode tube (CCFL). As the light emitting diode (LED), any of white LED light source, RGB-LED (light emitting diode in which R, G, B chips are molded in one package) light source, multi-color LED light source, and laser light source are preferable. Can be used.

  The substrate 3 used in the backlight device 1 of the present embodiment is not particularly limited as long as the point light source 2 can be mounted. For example, a metal substrate based on aluminum (Al), copper (Cu), or the like having high thermal conductivity can be preferably used.

  In the present embodiment, “mounting” refers to mounting an electronic component such as a light source on a substrate. In this embodiment, the method of attaching a light source etc. on a board | substrate is not specifically limited, For example, the method of attaching by soldering etc. are mentioned.

<Frame (light source holding member)>
The frame 4 used in the backlight device 1 of the present embodiment is not particularly limited as long as it has structural strength. Further, as the frame 4 used in the backlight device 1 of the present embodiment, for example, an aluminum alloy, a steel plate, stainless steel or the like can be preferably used. Examples of the aluminum alloy include materials such as A5052 (tensile strength 195 N / mm ² , thermal conductivity 138 W / m · K) and A6063 (tensile strength 185 N / mm ² , thermal conductivity 209 W / m · K). . Examples of the steel plate include SECC (thermal conductivity 70 W / m · K). Examples of stainless steel include materials such as SUS (thermal conductivity 15 W / m · K).

  The shape of the frame 4 used in the backlight device 1 of the present embodiment is a quadrangular prism shape having a rectangular or square cross section (the surface shown in FIGS. 3 and 4), or an L-shaped or U-shaped cross section. It has a polygonal column shape. The shape of the frame 4 will be specifically described below as “another embodiment”.

  The frame 4 has a surface perpendicular to the light exit surface of the light guide plate 22. Further, the frame 4 may or may not surround the light guide plate 22 with a surface perpendicular to the light emitting surface. Further, the frame 4 is preferably disposed as a structural reinforcing column at both ends of the chassis 5 so as to face two surfaces of the light guide plate 22 that are not adjacent to each other.

<Chassis (heat dissipation member)>
The chassis 5 used in the backlight device 1 of the present embodiment is not particularly limited as long as it has heat dissipation performance and structural strength. Moreover, as the chassis 5 used for the backlight device 1 of the present embodiment, for example, an aluminum alloy, a steel plate, stainless steel, or the like can be preferably used. Examples of the aluminum alloy include materials such as A5052 (tensile strength 195 N / mm ² , thermal conductivity 138 W / m · K) and A6063 (tensile strength 185 N / mm ² , thermal conductivity 209 W / m · K). . Examples of the steel plate include SECC (thermal conductivity 70 W / m · K). Examples of stainless steel include materials such as SUS (thermal conductivity 15 W / m · K).

<Heat conductive plate (thermal conductive member)>
As the heat conductive plate 6 used in the backlight device 1 of the present embodiment, a plate having high thermal conductivity is used. The thermal conductivity of the heat conductive plate 6 is preferably in the range of 200 W / m · K to 1000 W / m · K. When the thermal conductivity of the heat conducting plate 6 is less than 200 W / m · K, the heat conduction becomes insufficient and the heat does not spread to the heat radiating member, so the area contributing to heat radiation becomes small and the heat radiation performance is insufficient. It is not preferable for the reason. On the other hand, when the thermal conductivity of the heat conductive plate 6 is larger than 1000 W / m · K, it is not preferable because of its high price, softness and difficulty in use, and deterioration over time.

  In the present embodiment, the “thermal conductivity” is a value obtained by dividing the amount of heat flowing in a unit time through a unit area perpendicular to the heat flow by a temperature difference (temperature gradient) per unit length in heat conduction. (W / m · K).

  Further, in the present embodiment, “thermal resistance” is a value representing the difficulty of transmitting temperature, and means a temperature increase amount (° C./W) with respect to a heat generation amount per unit time.

  Moreover, as the heat conductive plate 6 used in the backlight device 1 of the present embodiment, structural strength is not required, so a material having high heat conductivity may be selected. For example, aluminum, copper, carbon, silver or the like can be preferably used. Examples of pure aluminum include materials such as A1050 (thermal conductivity 225 W / m · K). Examples of pure copper include materials such as C1100 (thermal conductivity 391 W / m · K). In addition, materials such as a sheet containing a filler such as carbon and silver, and a metal flat plate with a built-in heat pipe can be used.

  The thermal conductivity of the heat conductive plate 6 used in the backlight device 1 of the present embodiment is preferably larger than the thermal conductivity of the frame 4 and the chassis 5. Moreover, as thickness of the heat conductive board 6, about 0.5-2 mm is preferable.

  Examples of the shape of the heat conductive plate 6 used in the backlight device 1 of the present embodiment include L-shaped shapes shown in FIGS.

  In the backlight device 1 of the present embodiment, since the chassis 5 and the heat conducting plate 6 are in contact with each other, the heat distribution in the chassis 5 is uniform, and the heat dissipation performance can be further improved.

<Regarding the contact between the heat conductive plate (heat conductive member) and the chassis (heat radiating member)>
As shown in FIGS. 1 to 3, the heat conductive plate 6 faces the light guide plate 22 of the first plate-like portion 55 that contacts the surface of the frame 4 facing the light guide plate 22 and the chassis 5. A second plate-like portion 56 that is in contact with the surface to be touched.

  The shape of the 1st plate-shaped part 55 and the 2nd plate-shaped part 56 should just be a shape which can contact the flame | frame 4 or the chassis 5, and is not specifically limited. For example, each of the first plate-like portion 55 and the second plate-like portion 56 may be a rectangular plate, a square plate, or the like, but is not limited thereto. It is preferable that the 1st plate-shaped part 55 and the 2nd plate-shaped part 56 are mutually connected so that it may become substantially perpendicular | vertical.

  The contact surface between the chassis 5 and the second plate-like portion 56 is provided with a plurality of fixing portions 50 that strengthen the contact between the chassis 5 and the second plate-like portion 56.

  The fixing part 50 is not particularly limited as long as it can firmly make contact between the chassis 5 and the second plate-like part 56. For example, a screw, welding, pressure welding, soldering, pressure-sensitive adhesive tape, pressure-sensitive adhesive sheet, adhesive, caulking, or inset is preferable. Among these, a screw is more preferable.

  In the lighting device according to the present embodiment, the fixing portion 50 is linearly arranged on a plurality of rows along the first direction on the contact surface between the chassis 5 and the second plate-like portion 56, and the plurality The fixed portions 50 arranged on two adjacent rows of the rows are not arranged linearly along the second direction orthogonal to the first direction. More specifically, the fixing portions 50 are preferably arranged in a staggered manner.

  The specific directions of the first direction and the second direction are not particularly limited. For example, the second direction may be a light incident direction from the point light source 2 to the light guide plate 22, and in this case, the first direction is a direction orthogonal to the light incident direction.

  The number of the columns is not particularly limited as long as it is plural. The lighting device of this embodiment can use any number of rows of two or more. From the viewpoint of facilitating the manufacturing process of the lighting device by reducing the number of the fixing parts 50, it can be said that two rows are more preferable. If it is this invention, even if it is two rows, the thermal resistance between the chassis 5 and the 2nd plate-shaped part 56 can be made small. As a result, the heat conduction from the point light source 2 to the chassis 5 is further improved, so that the heat dissipation performance of the lighting device can be improved.

  The distance between the rows is not particularly limited, but it is preferable that the distance between two adjacent rows of the plurality of rows decreases in the second direction. Note that the specific distance between two adjacent rows is not particularly limited.

  The arrangement of the fixing portions 50 arranged on a plurality of rows may be an arrangement in which the three fixing portions 50 are located at the vertices of the equilateral triangle. For example, consider the adjacent first and second rows. Note that either the first row or the second row may be close to the first plate-like portion 55. At this time, two fixed portions 50 arranged adjacent to each other on the first row and one fixed portion 50 on the second row at the shortest distance from both of these fixed portions 50 are equilateral triangles. Can be placed at each vertex.

  Although the distance between the fixing | fixed part 50 arranged on one row | line | column is not specifically limited, For example, it is preferable that they are 3 cm-15 cm, and it is more preferable that they are 6 cm-12 cm.

  The interval between the fixed portions 50 on one row may be the same or different. If they are different, it is preferable that the interval between the fixing portions 50 on each row decreases in the first direction.

  The number of fixing portions 50 arranged on each row is not particularly limited, but the number of fixing portions 50 arranged on the most distal row from the first plate-like portion 55 is the largest, and the first plate-like shape. It is preferable that the number of the fixing portions 50 arranged on the most proximal row from the portion 55 is the smallest. Further, the fixing portion 50 arranged at the end of the most distal row from the first plate-like portion 55 is more than the fixing portion 50 arranged at the end of the most proximal row from the first plate-like portion 55. It is preferable that it is arranged outside the first direction.

  The arrangement of the fixing unit 50 will be described in more detail with reference to FIG. FIGS. 8A and 8B are schematic views showing the arrangement of the fixing portions 50 when the second plate-like portion 56 is viewed from the light emitting surface side. In the second plate-like portion 56, a plurality of fixing portions 50 are arranged on two rows in the first direction. As shown in (b), the second plate-like portion 56 may be provided with a notch. In this case, a desired notch may be provided after determining the arrangement of the fixing portion 50 in accordance with the present specification assuming a state in which there is no notch.

  For example, if a 68-inch LCD-TV or the like is manufactured based on the lighting device of the present embodiment, a total of 29 fixed portions 50 can be arranged on two rows for one light source. is there. The number of fixing parts 50 arranged in each of the two columns is not particularly limited. For example, 15 fixing parts 50 are arranged on one column, and 14 fixing units 50 are arranged on the other column. It is possible. In this case, it is possible to arrange 15 fixing parts 50 on the row distal to the light source and arrange 14 fixing parts 50 on the row proximal to the light source.

  If it is the said structure, compared with the case where 72 screws are arrange | positioned with respect to the light source of one side, substantially the same heat dissipation performance is realizable. For example, in the case of 72 screws, the LED temperature is 34.6 ° C. (170.8 W), and the LED temperature is 34.9 ° C. (171.6 W) with 29 screws. Is also possible.

<Light guide plate (light guide member)>
The light guide plate 22 used in the backlight device 1 of the present embodiment has a light incident surface and a light emitting surface perpendicular to the light incident surface, and can emit light incident from the light source 7. There is no particular limitation as long as it is possible.

<Other members>
In the liquid crystal display device 10 according to the present embodiment, as the reflection sheet 21, the optical sheet 23, the liquid crystal panel 24, and the bezel 25, those provided in a conventionally known liquid crystal display device can be used.

<Relevance of each member>
The relevance of each member in the backlight device 1 of the present embodiment will be specifically described below with reference to FIG.

  As shown in FIG. 4, when the frame 4 has the function of the heat conduction plate 6 and the heat conduction plate 6 is omitted, the frame 4 has both the structural strength and the heat conductivity. Will have to. However, in general, it is difficult to make the two performances compatible. For example, the thermal conductivity of A5052, which is a general aluminum alloy (excellent in structural strength) as a structural member, is higher than that of SUS or the like, but is less than half that of C1100, which is pure copper. On the other hand, A1050, which is pure aluminum excellent in thermal conductivity, has insufficient strength to use as a structural member (inferior in structural strength). A1050 is inferior to A5052 in all respects: tensile strength, shear strength and yield strength. In addition, since A1050 is inferior in hardness, there is a problem that even if tapping is performed for screw fastening, the effect of tapping is actually easily lost. Therefore, in order to have both the performance of structural strength and thermal conductivity, the thermal conductive plate 6 is essential separately from the frame 4.

  Conversely, if the frame 4 is omitted and the structural strength is secured by the chassis 5 and only the heat conductive plate 6 is adopted from the viewpoint of thermal conductivity, it is a small and medium size panel such as a mobile phone and a car navigation system. Since the total amount of light required for the light source is small, there is a possibility that the two performances can be compatible. However, in large displays such as liquid crystal televisions and digital signage displays, the weight increases in terms of area. Therefore, if the structural strength can be maintained only by the chassis 5, the thickness of the chassis 5 is increased in proportion to the increase in size. Need to increase. In that case, it is not realistic in terms of weight, material cost, workability and the like. Therefore, the frame 4 is indispensable separately from the chassis 5 in order to achieve the structural strength by setting the chassis 5 to about 2 mm or less which is a realistic thickness.

  Accordingly, the structural strength is assigned to the frame 4 and the thermal conductivity is assigned to the thermal conductive plate 6 respectively, and the best performance as a whole can be exhibited by using optimal members for each.

  In addition, even with the same edge light type backlight, as the size of the backlight has increased, the long side of the four-sided incident light to the two-sided incident light and the two-sided incident light have a longer side from the upper and lower light incidents. If the left and right incident light and the form change, the thermal conditions become more severe due to the dense heat sources. For this reason, it is even more important to share the roles of the structural strength member and the heat conductive member as described above and to maximize the performance of each member.

<Method of heat conduction>
A method of heat conduction in the backlight device 1 of the present embodiment will be specifically described below with reference to FIGS. 1 to 3 and FIGS. In the following description, the light source 7 is described as an example in which the point light source 2 is carried on the substrate 3.

  Heat generated from the point light source 2 such as an LED is first transmitted to the substrate 3. At this time, the thickness of the substrate 3 is generally about 1 to 2 mm in the case of a metal substrate, and the length in the longitudinal direction of the substrate 3 is the length of one side of the screen. Generally, it is about 300 mm to 1200 mm. A plurality of point light sources 2 are arranged in the longitudinal direction of the substrate 3. As the size of the point light source 2, a rectangle (rectangle, square, etc.) having a side of about 3 mm to 10 mm is generally used.

  In that case, heat conduction in the thickness direction of the substrate 3 is relatively good because heat is transferred within the range of the size of the point light source 2. However, since the heat conduction in the longitudinal direction of the substrate 3 proceeds only in the range of the thickness direction of the substrate 3, it is inferior to the heat conduction in the thickness direction. For this reason, distribution arises in heat by arrangement | positioning etc. of LED.

  Specifically, the LEDs near the center are densely populated with other LEDs on both sides, so heat is trapped. On the other hand, since the LED arranged at the end has no heat source next to it, heat is likely to diffuse. As a result, the heat generated by the point light source 2 has a heat distribution in the longitudinal direction of the substrate 3. In general, the luminous efficiency of an LED varies depending on the temperature. If all the LEDs are operated in a state where the heat generation state varies depending on each LED, the light emission state is different, which leads to occurrence of luminance unevenness in the backlight device 1, and this state is not preferable. The present embodiment can eliminate this state. The principle is as follows.

  According to the present embodiment, the substrate 3 is in contact with the frame 4 via the heat conductive plate 6. The heat conductive plate 6 is formed of a material having high heat conductivity as described above. The frame 4 is a member that maintains structural strength, and thus has a larger cross-sectional area than the substrate 3. Therefore, the thermal resistance in the longitudinal direction of the frame 4 is smaller than that of the substrate 3, and sufficient thermal diffusion is performed in the heat conductive plate 6 and the frame 4. As a result, an effect of making the temperature of the substrate 3 uniform is produced, and variations in the operating temperature of the LEDs are reduced, so that uneven brightness in the backlight device 1 can be suppressed.

  In addition, heat uniformity has the effect of reducing thermal resistance. The mechanism by which heat conduction deteriorates when the heat distribution is uneven is explained as follows.

  FIGS. 5A and 5B are cross-sectional views when heat sources 12 and 13 having different sizes are mounted on a certain heat conductor 11. The thermal conductor 11 is the same in FIGS. 5A and 5B and has the same thermal conductivity, so the thermal resistance per unit area is also the same.

  When the same amount of heat is given to each of the heat sources 12 and 13 per unit time, heat is conducted through the heat conductor 11 according to the 45 degree rule. However, in a cross section A of the heat conductor 11, in the case of FIG. 5B compared to the case of FIG. 5A, the region contributing to heat conduction is narrow, and heat concentrates in a narrow area. Since the thermal resistance per unit area in the thermal conductor 11 is equal, in the case of FIG. 5B compared to the case of FIG. 5A, the thermal resistance increases because the area contributing to heat conduction is small. Accordingly, it can be seen that the temperature difference between the upper and lower sides of the heat conductor 11 is larger in the case of FIG. 5B than in the case of FIG.

  Therefore, if the heat conduction of the heat conductor 11 is improved when the same amount of heat is input per unit time, it is better to conduct the heat after expanding the heat in terms of area. I understand. It can also be seen that the heat conduction is best when the heat distribution is uniform.

  According to the present embodiment, the heat transferred from the substrate 3 to the heat conducting plate 6 and the frame 4 is transferred to the chassis 5 in a state having a uniform distribution. For this reason, heat conduction is performed to the chassis 5 in a state with good heat conduction. And if the heat conduction to the chassis 5 is good, the temperature of the chassis 5 becomes high and the temperature difference from the atmospheric temperature is widened, so that the efficiency of heat exchange increases. As a result, the heat dissipation performance of the backlight device 1 is improved. Furthermore, the heat distribution in the planar direction of the chassis 5 is made uniform by adopting a configuration in which the thermal resistance in the planar direction of the heat conducting plate 6 is smaller than the thermal resistance in the planar direction of the chassis 5. Therefore, the heat dissipation performance can be improved.

  In addition, it is desirable that a heat conduction auxiliary material such as a resin sheet, a metal sheet, or grease is inserted between each member in the backlight device 1 because the thermal resistance at the interface can be further lowered.

<Other embodiments>
As another example of the backlight device 1 in the present embodiment, there is one in which the shape of the frame 4 is changed. Specifically, this will be specifically described with reference to FIGS. 6 (a) and 6 (b) and FIG.

  As shown in FIGS. 6A and 6B, the shape of the frame 4 is a polygonal column shape having a U-shaped cross section (the surface shown in FIGS. 3 and 4), or the frame as shown in FIG. By making the shape of 4 into a polygonal column shape having an L-shaped cross section, material costs can be reduced compared to a rectangular column shape having a rectangular or square cross section, and a U-shaped, L-shaped, etc. Thus, the mechanical strength can be increased by bending the flat plate.

  That is, in the illumination device of the present embodiment, a plane perpendicular to both the first surface where the light source holding member and the heat conductive member are in contact and the second surface where the light source holding member and the heat dissipation member are in contact with each other. The cross-sectional shape of the light source holding member is preferably rectangular or square. In the illumination device of the present embodiment, the plane is perpendicular to both the first surface where the light source holding member and the heat conductive member are in contact and the second surface where the light source holding member and the heat dissipation member are in contact. It is also preferable that the shape of the cross section of the light source holding member is L-shaped or U-shaped.

  The illumination device of this embodiment can also be configured as follows.

  The illuminating device of this embodiment is installed substantially perpendicularly to the chassis, the surface of the chassis, the substrate having a point light source on one side, the first plate-like portion connected to the substrate, and the chassis. A heat conduction plate comprising at least two plate-like portions of the second plate-like portion, wherein the second plate-like portion extends in the light emitting direction, and the second plate-like portion The chassis and the chassis are fastened by a fixing portion, and the fastening positions by the fixing portion are arranged in a zigzag pattern in two or more rows substantially perpendicular to the light emission direction.

  In the illuminating device of this embodiment, it is preferable that the row | line | column far from a board | substrate becomes a row | line with many fixed parts than the row | line | column near the board | substrate. In addition, when the notch is provided in the 2nd plate-shaped part, the number of fixing | fixed parts will be calculated supposing the state without a notch.

(II) Manufacturing method of lighting device in the present embodiment The manufacturing method of the lighting device in the present embodiment connects the light source 7 (the point light source 2 and the substrate 3), the heat conduction plate 6, the frame 4 and the chassis 5 in order. I will do it. Thereafter, the light guide plate 22 is disposed. As a means for connecting each member, in addition to screwing, for example, fixing with an adhesive tape, an adhesive, or the like; fitting; pressing;

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  INDUSTRIAL APPLICABILITY The present invention is suitably used for a surface emitting backlight device provided in a liquid crystal display device such as a mobile phone, a notebook personal computer, and a television, particularly a side edge type large backlight device using a point light source such as an LED as a light source. can do.

1 Backlight device (lighting device)
2 Point light source (light emitting element, light source)
3 Substrate 4 Frame (Light source holding member)
5 Chassis (heat dissipation member)
6 Thermal conductive plate (thermal conductive member)
7 Light source 8 Light source 10 Liquid crystal display device (image display device)
DESCRIPTION OF SYMBOLS 11 Heat conductor 12 Heat source 13 Heat source 21 Reflection sheet 22 Light guide plate (light guide member)
23 Optical sheet 24 Liquid crystal panel 25 Bezel (outer frame)
30 Liquid crystal display device (image display device)
31 Backlight device (lighting device)
33 Substrate 50 Fixed part 55 First plate-like part 56 Second plate-like part

Claims (7)

A light source, a light guide member having a light incident surface and a light exit surface perpendicular to the light incident surface, a light source holding member for disposing the light source toward the light incident surface, and a back surface of the light guide member A heat dissipating member disposed facing the light emitting surface and connected to the light source holding member, and a heat conductive member in contact with the light source holding member and the heat dissipating member,
The heat conductive member is in contact with a first plate-like portion that is in contact with a surface of the light source holding member that faces the light guide member, and a surface of the heat dissipation member that is opposed to the light guide member. Has a second plate-like part,
The light source is disposed on a surface facing the light incident surface of the light source holding member via a first plate-shaped portion,
The contact surface between the heat radiating member and the second plate-like portion is provided with a plurality of fixing portions that strengthen the contact between the heat radiating member and the second plate-like portion,
The fixing portions are arranged linearly on a plurality of rows along the first direction on the contact surface,
The fixing device arranged on two adjacent rows among the plurality of rows is not arranged linearly along a second direction orthogonal to the first direction.   The lighting device according to claim 1, wherein the second direction is a light incident direction from the light source to the light guide member.   The lighting device according to claim 1, wherein the fixing portion is formed by screwing.   The number of fixed parts arranged on the most distal row from the first plate-like part is the largest, and the number of fixed parts arranged on the most proximal line from the first plate-like part is the smallest, The illuminating device of any one of Claims 1-3.   The lighting device according to any one of claims 1 to 4, wherein an interval on each row of the fixing portions arranged on the row along the first direction decreases toward the first direction. .   The lighting device according to any one of claims 1 to 5, wherein a distance between two adjacent rows of the plurality of rows decreases in a second direction.   An image display device comprising the illumination device according to claim 1.

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