JP7567213B2 - Illumination device for display device, and display device - Google Patents

Description

The present invention relates to a lighting device for a display device and a display device.

Transmissive or semi-transmissive liquid crystal display devices are equipped with an illumination device on the back side of the liquid crystal display panel. The illumination device includes a light-emitting element as a light source, and a light guide plate that uniformly irradiates the light emitted from the light-emitting element onto the surface of the liquid crystal display panel. The light-emitting element is, for example, a white LED.

Light-emitting elements generate heat. If the heat generated by the light-emitting element causes the temperature of the light-emitting element itself and its surroundings to rise, the characteristics of the light-emitting element will deteriorate and its lifespan will be shortened. In addition, the heat generated by the light-emitting element will also deteriorate the characteristics of the elements arranged around the light-emitting element. Therefore, it is important to take measures to dissipate the heat generated by the light-emitting element.

JP 2010-170922 A

The present invention provides a lighting device for a display device that can prevent the deterioration of characteristics due to heat generated by light-emitting elements.

The display device lighting device according to the first aspect of the present invention comprises a flexible printed wiring board, first and second light-emitting elements provided on the bottom surface of the flexible printed wiring board, electrically connected to wiring within the flexible printed wiring board, and arranged along a first direction, a light guide plate arranged to receive light emitted from the first and second light-emitting elements at its side and emitting light from the first and second light-emitting elements from its top surface, a first heat dissipation element provided on the bottom surface of the flexible printed wiring board and arranged between the first and second light-emitting elements, and a first adhesive member that bonds the first heat dissipation element to the light guide plate.

The display device lighting device according to the second aspect of the present invention is the display device lighting device according to the first aspect, further comprising a third light-emitting element arranged adjacent to the second light-emitting element, a second heat dissipation element arranged between the second and third light-emitting elements, and a second adhesive member that bonds the second heat dissipation element to the light guide plate.

The display device lighting device according to the third aspect of the present invention comprises a flexible printed wiring board, a plurality of light-emitting elements provided on the bottom surface of the flexible printed wiring board, electrically connected to wiring within the flexible printed wiring board, and arranged along a first direction, a light guide plate arranged to receive light emitted from the plurality of light-emitting elements on the side and emitting light from the plurality of light-emitting elements from the top surface, a first heat dissipation element provided on the bottom surface of the flexible printed wiring board, arranged on one side of the plurality of light-emitting elements, and radiating heat, and a first adhesive member that bonds the first heat dissipation element to the light guide plate.

The display device lighting device according to the fourth aspect of the present invention is the display device lighting device according to the third aspect, further comprising a second heat dissipation element arranged on the other side of the plurality of light-emitting elements, and a second adhesive member that bonds the second heat dissipation element to the light guide plate.

The display device lighting device according to the fifth aspect of the present invention is the display device lighting device according to any one of the first to fourth aspects, further comprising an adhesive member that bonds a portion of the bottom surface of the flexible printed wiring board to a portion of the light guide plate.

The sixth aspect of the present invention relates to a lighting device for a display device according to any one of the first to fifth aspects, in which the heat dissipation element is a dummy light-emitting element.

The seventh aspect of the present invention relates to a lighting device for a display device, which is the lighting device for a display device of the sixth aspect, in which the dummy light-emitting element is not electrically connected to the wiring in the flexible printed wiring board.

The display device according to the eighth aspect of the present invention comprises an illumination device according to any one of the first to sixth aspects and a display panel that transmits light from the illumination device and displays an image.

The present invention provides a lighting device for a display device that can prevent the deterioration of characteristics due to heat generated by the light-emitting element.

FIG. 1 is a plan view of a liquid crystal display device according to a first embodiment of the present invention. FIG. 2 is a plan view of the liquid crystal display device with the upper case removed. FIG. 3 is a cross-sectional view of the liquid crystal display taken along the line AA' shown in FIGS. FIG. 4 is a cross-sectional view of the liquid crystal display taken along the line BB' shown in FIGS. FIG. 5 is a cross-sectional view showing an example of a liquid crystal display panel. FIG. 6 is a plan view of a main part of the lighting device according to the first embodiment. FIG. 7 is a cross-sectional view of the lighting device taken along line CC' shown in FIG. FIG. 8 is a plan view of a main part of an illumination device according to a second embodiment of the present invention.

The following describes the embodiments with reference to the drawings. However, the drawings are schematic or conceptual, and the dimensions and ratios of each drawing are not necessarily the same as those in reality. Furthermore, even when the same parts are shown in different drawings, the dimensional relationships and ratios between the drawings may be different. In particular, the following embodiments are examples of devices and methods for embodying the technical idea of the present invention, and the shape, structure, arrangement, etc. of the components do not specify the technical idea of the present invention. In the following description, elements having the same function and configuration are given the same reference numerals, and duplicate descriptions are omitted.

[1] First Embodiment Hereinafter, a liquid crystal display device will be described as an example of a display device.

[1-1] Configuration of liquid crystal display device 1 Fig. 1 is a plan view of a liquid crystal display device 1 according to a first embodiment of the present invention. Fig. 2 is a plan view of the liquid crystal display device 1 excluding an upper case. Fig. 3 is a cross-sectional view of the liquid crystal display device 1 taken along line A-A' shown in Figs. 1 and 2. Fig. 4 is a cross-sectional view of the liquid crystal display device 1 taken along line B-B' shown in Figs. 1 and 2. The direction along line A-A' is the X direction, and the direction perpendicular to line A-A' is the Y direction.

The liquid crystal display device 1 includes an illumination device 2, an LCD panel 3, a frame 4, a lower case 5, and an upper case 6. The illumination device 2 is also called a backlight.

The lower case 5 houses the lighting device 2, the liquid crystal display panel 3, and the frame 4. The lower case 5 has a rectangular shape in a plan view. The inner size of the lower case 5 is set to be the same as or slightly larger than the outer shape of the frame 4. The lower case 5 is made of, for example, metal.

An opening 5A is provided on one side of the lower case 5 in the X direction. The opening 5A is for pulling out the flexible printed wiring board to the outside.

The frame 4 fixes the lighting device 2 and the liquid crystal display panel 3 in the desired positions. The frame 4 has a rectangular frame shape. The frame 4 is made of resin.

The frame 4 has a step 4A. The size of the opening in the frame 4 below the step 4A is set to be the same as or slightly larger than the size of the lighting device 2, and the lighting device 2 is fitted into this opening. The liquid crystal display panel 3 is placed on the step 4A. The size of the opening in the frame 4 above the step 4A is set to be the same as or slightly larger than the size of the liquid crystal display panel 3, and the liquid crystal display panel 3 is fitted into this opening.

An opening 4B is provided on one side of the frame 4 in the X direction. The opening 4B is for pulling out the flexible printed wiring board to the outside.

The upper case 6 covers the lower case 5 and fixes the liquid crystal display panel 3 from above. The upper case 6 has a rectangular shape in a plan view. The inside size of the upper case 6 is set to be the same as or slightly larger than the outer shape of the lower case 5. The upper case 6 is made of, for example, metal.

An opening 6A is provided at the top of the upper case 6 to expose the screen of the liquid crystal display panel 3. An opening 6B is provided at one side of the upper case 6 in the X direction. The opening 6B is for pulling out the flexible printed wiring board to the outside. The upper case 6 and the lower case 5 are fixed to each other by a fixing member (not shown).

The lighting device 2 is a side light type (edge light type). The lighting device 2 includes a plurality of light emitting elements 10 as a light source, a flexible printed circuit (FPC) 11, an adhesive member 12, a reflective sheet 13, a light guide plate 14, a diffusion sheet 15, a prism sheet 16, and a prism sheet 17. The reflective sheet 13, the light guide plate 14, the diffusion sheet 15, the prism sheet 16, and the prism sheet 17 are laminated in this order. The reflective sheet 13, the light guide plate 14, the diffusion sheet 15, the prism sheet 16, and the prism sheet 17 each have a rectangular shape.

Each of the multiple light-emitting elements 10 emits white light. The light-emitting elements 10 are, for example, LEDs (light-emitting diodes).

The multiple light-emitting elements 10 are provided on the bottom surface of the flexible printed wiring board 11. The light-emitting elements 10 are attached to the flexible printed wiring board 11 by solder or the like, and are electrically connected to wiring provided within the flexible printed wiring board 11. Power is supplied to the light-emitting elements 10 via the flexible printed wiring board 11. In actual manufacturing, the light-emitting elements 10 are attached with the bottom surface of the flexible printed wiring board 11 facing up, and are mounted on the liquid crystal display device 1 so that the light-emitting elements 10 are located below the flexible printed wiring board 11. The light-emitting elements 10 are arranged on the side of the light guide plate 14 and are arranged so as to emit light toward the side of the light guide plate 14.

The flexible printed wiring board 11 is a type of printed board and is also called a flexible printed circuit board. The flexible printed wiring board 11 is a film-like printed board in which an electrical circuit is formed on a substrate made of a thin, soft, insulating base film and a conductive metal laminated together.

The adhesive member 12 bonds the flexible printed wiring board 11 and the light guide plate 14. The adhesive member 12 also bonds the flexible printed wiring board 11 and the frame 4. The adhesive member 12 is formed of, for example, double-sided tape.

A reflective sheet 13 is provided on the lower case 5. The reflective sheet 13 reflects light leaking from the lower part of the light guide plate 14 back towards the light guide plate 14.

The light guide plate 14 is an optical component for uniformly irradiating the light emitted from the light emitting element 10 onto the surface of the liquid crystal display panel 3. The light guide plate 14 is made of a light-transmitting material such as acrylic resin or polycarbonate.

The diffusion sheet 15 is intended to make the brightness of the light within the display screen more uniform. The prism sheets 16 and 17 are intended to adjust the orientation angle of the emitted light and improve the brightness at the front. A more specific configuration of the illumination device 2 will be described later.

(Configuration of Liquid Crystal Display Panel 3)
The liquid crystal display panel 3 includes substrates 21 and 22, polarizing plates 23 and 24, and a driver 25. A liquid crystal layer and the like are disposed between the substrates 21 and 22. In Fig. 3, the members between the substrates 21 and 22 are not shown. The polarizing plate 23 is laminated on one main surface of the substrate 21. The polarizing plate 24 is laminated on one main surface of the substrate 22.

A driver 25 is disposed at the end of the substrate 21 in the X direction. The driver 25 is a circuit that drives a plurality of pixels included in the liquid crystal display panel 3. The driver 25 is composed of an IC (Integrated Circuit).

A flexible printed circuit board 26 is connected to the end of the substrate 21 in the X direction. The flexible printed circuit board 26 is electrically connected to the driver 25.

A touch panel is generally provided on the liquid crystal display panel 3, but is not shown in the figure.

Figure 5 is a cross-sectional view showing an example of a liquid crystal display panel 3.

The liquid crystal display panel 3 includes a TFT substrate 21 on which switching elements and pixel electrodes are formed, and a color filter substrate (CF substrate) 22 on which color filters and common electrodes are formed and disposed opposite the TFT substrate 21. Each of the TFT substrate 21 and the CF substrate 22 is composed of a transparent substrate (e.g., a glass substrate or a plastic substrate). The TFT substrate 21 is disposed on the lighting device 2 side, and illumination light from the lighting device 2 enters the liquid crystal display panel 3 from the TFT substrate 21 side. Of the two main surfaces of the liquid crystal display panel 3, the main surface opposite the lighting device 2 is the display surface of the liquid crystal display panel 3.

The liquid crystal layer 30 is filled between the TFT substrate 21 and the CF substrate 22. Specifically, the liquid crystal layer 30 is enclosed in an area surrounded by the TFT substrate 21, the CF substrate 22, and a sealant (not shown) that bonds them together. The sealant is made of, for example, an ultraviolet curing resin, a thermosetting resin, or a combined ultraviolet and heat curing resin, and is applied to the TFT substrate 21 or the CF substrate 22 in the manufacturing process and then cured by ultraviolet irradiation, heating, or the like.

The liquid crystal material constituting the liquid crystal layer 30 changes its optical characteristics as the orientation of the liquid crystal molecules is manipulated in response to the electric field applied between the TFT substrate 21 and the CF substrate 22. Various liquid crystal modes can be applied, including the VA (Vertical Alignment) mode, the TN (Twisted Nematic) mode, and the homogeneous mode.

A plurality of switching elements (active elements) 31 are provided on the liquid crystal layer 30 side of the TFT substrate 21. For example, a TFT (Thin Film Transistor) is used as the switching element 31, and an n-channel TFT is also used. The TFT 31 includes a gate electrode that functions as a scanning line, a gate insulating film provided on the gate electrode, a semiconductor layer (e.g., an amorphous silicon layer) provided on the gate insulating film, and a source electrode and a drain electrode that are partially in contact with the semiconductor layer and spaced apart from each other. The source electrode is electrically connected to a signal line.

An insulating layer 32 is provided on the TFT 31. A plurality of pixel electrodes 33 corresponding to a plurality of pixels are provided on the insulating layer 32. A contact plug (contact hole) 34 electrically connected to the pixel electrode 33 is provided in the insulating layer 32 and on the drain electrode of the TFT 31.

A color filter 35 is provided on the liquid crystal layer 30 side of the CF substrate 22. The color filter 35 has multiple colored filters (colored members), specifically multiple red filters 35-R, multiple green filters 35-G, and multiple blue filters 35-B. A typical color filter is composed of the three primary colors of light: red (R), green (G), and blue (B). A set of adjacent R, G, and B colors forms a display unit (pixel), and a single R, G, or B color part in one pixel is the smallest driving unit called a subpixel. A TFT 31 and a pixel electrode 33 are provided for each subpixel.

A black matrix (light-shielding film) 36 for blocking light is provided at the boundaries between the red filter 35-R, green filter 35-G, and blue filter 35-B, and at the boundaries between pixels (sub-pixels). In other words, the black matrix 36 is formed in a mesh pattern. The black matrix 36 has the function of blocking unnecessary light between colored members, for example, and improving contrast.

A common electrode 37 is provided on the color filter 35 and the black matrix 36. The common electrode 37 is formed in a planar shape over the entire display area of the liquid crystal display panel 3.

A polarizing plate 23 is laminated on the side of the TFT substrate 21 opposite the liquid crystal layer 30, and a polarizing plate 24 is laminated on the side of the CF substrate 22 opposite the liquid crystal layer 30. The polarizing plates 23 and 24 are arranged so that their transmission axes are perpendicular to each other, that is, in a crossed Nicol state. A quarter-wave plate may be provided between the TFT substrate 21 and the polarizing plate 23. A quarter-wave plate may be provided between the CF substrate 22 and the polarizing plate 24.

The pixel electrode 33, the contact plug 34, and the common electrode 37 are made of transparent electrodes, for example, ITO (indium tin oxide). The insulating layer 32 is made of a transparent insulating material, for example, silicon nitride (SiN).

As shown in FIG. 3, the liquid crystal display panel 3 is adhered to the lighting device 2 by an adhesive member 27. Specifically, the polarizer 23 of the liquid crystal display panel 3 is adhered to the prism sheet 17 of the lighting device 2 by the adhesive member 27. The adhesive member 27 includes a frame-shaped portion formed along the outer periphery of the liquid crystal display panel 3. The substrate 21 of the liquid crystal display panel 3 is adhered to the flexible printed wiring board 11 of the lighting device 2 by a spacer 28 and the adhesive member 27. The adhesive member 27 includes a portion having substantially the same shape as a portion of the flexible printed wiring board 11 that extends along the arrangement direction of the multiple light-emitting elements 10. The adhesive member 27 is made of, for example, double-sided tape. The spacer 28 is made of resin.

[1-2] Specific configuration of the illumination device 2 Next, a specific configuration of the illumination device 2 will be described. Fig. 6 is a plan view of a main part of the illumination device 2 according to the first embodiment. Fig. 7 is a cross-sectional view of the illumination device 2 taken along line CC' shown in Fig. 6. In Fig. 6, the reflective sheet, the diffusion sheet 15, and the prism sheets 16 and 17 are omitted from illustration.

The lighting device 2 includes a plurality of light-emitting elements 10. FIG. 6 shows three light-emitting elements 10-1 to 10-3 as an example. The three light-emitting elements 10-1 to 10-3 are adhered to the bottom surface of the flexible printed wiring board 11 and are electrically connected to the wiring within the flexible printed wiring board 11.

The three light-emitting elements 10-1 to 10-3 are arranged along the Y direction. The three light-emitting elements 10-1 to 10-3 are arranged to face the side of the light guide plate 14, and are arranged with a small gap between them. By making the gap between the light-emitting elements 10-1 to 10-3 and the light guide plate 14 the same, the light distribution can be stabilized. The three light-emitting elements 10-1 to 10-3 are evenly arranged at equal intervals along the Y direction. This allows the three light-emitting elements 10-1 to 10-3 to irradiate light more uniformly over the entire side of the light guide plate 14.

The lighting device 2 includes multiple heat dissipation elements 40. FIG. 6 shows two heat dissipation elements 40-1 and 40-2 as an example. The heat dissipation elements 40 have the function of radiating heat generated by the light emitting element 10, and also have the function of dissipating heat by transmitting the heat generated by the light emitting element 10 to the light guide plate 14.

The heat dissipation element 40 is made of a material capable of conducting heat. In this embodiment, the heat dissipation element 40 has the same configuration as the light emitting element 10, that is, it is made of a dummy light emitting element. When a dummy light emitting element is used as the heat dissipation element 40, the dummy light emitting element and the light emitting element can be bonded to the flexible printed wiring board in the same manufacturing process, making the manufacturing process easier. The heat dissipation element 40 is not limited to a dummy light emitting element, and may be a resistive element or may be made of a metal such as copper (Cu). When the heat dissipation element 40 is made of something other than a dummy light emitting element, the size of the heat dissipation element 40 is set to be approximately the same as the size of the light emitting element 10.

The heat dissipation element 40 is adhered to the bottom surface of the flexible printed wiring board 11. The method of adhering the heat dissipation element 40 to the flexible printed wiring board 11 is the same as that of the light emitting element 10. Unlike the light emitting element 10, the heat dissipation element 40 is not electrically connected to the wiring in the flexible printed wiring board 11. The heat dissipation element 40-1 is disposed between the two light emitting elements 10-1 and 10-2, and the heat dissipation element 40-2 is disposed between the two light emitting elements 10-2 and 10-3.

The heat dissipation element 40 is adhered to the side of the light guide plate 14 by an adhesive member 41. The adhesive member 41 is, for example, made of double-sided tape. This makes it easier for the heat dissipation element 40 to conduct heat to the light guide plate 14 via the adhesive member 41. In addition, because the heat dissipation element 40 and the light guide plate 14 are fixed together, even if the liquid crystal display panel 3 receives an impact, the light guide plate 14 can be prevented from shifting. This prevents the light guide plate 14 from coming into contact with the light emitting element 10, and prevents the light emitting element 10 from breaking down due to an impact.

[1-3] Advantages of the First Embodiment The light-emitting elements 10, for example LEDs, generate heat. The characteristics of the light-emitting elements 10 deteriorate due to heat, and the life span of the light-emitting elements 10 is shortened. In this embodiment, the lighting device 2 includes a plurality of heat dissipation elements (dummy light-emitting elements) 40 provided between the plurality of light-emitting elements 10. The plurality of heat dissipation elements 40 are adhered to the light guide plate 14 by an adhesive member 41.

According to this embodiment, the heat generated by the light-emitting element 10 is conducted to the light guide plate 14 via the flexible printed wiring board 11, the heat dissipation element 40, and the adhesive member 41. The heat can then be radiated from the light guide plate 14. This makes it possible to prevent the temperature of the light-emitting element 10 from increasing, thereby preventing the characteristics of the light-emitting element 10 from deteriorating.

The light guide plate 14 and the heat dissipation element 40 are also bonded together by an adhesive member 41. This prevents the light guide plate 14 from moving from a predetermined position when an impact is applied to the liquid crystal display device 1. This prevents the light guide plate 14 from colliding with the light emitting element 10, thereby preventing the light emitting element 10 from breaking down.

The light guide plate 14 and the heat dissipation element 40 can also be fixed together. This allows the gap between the multiple light emitting elements 10 and the light guide plate 14 to always be kept uniform. This allows the light distribution of the lighting device 2 to be stabilized.

[2] Second Embodiment In the second embodiment, two heat dissipation elements 40 are arranged on both sides of a plurality of light emitting elements 10 .

Figure 8 is a plan view of the main parts of a lighting device 2 according to a second embodiment of the present invention. The cross-sectional view along the X direction through the heat dissipation element 40 is the same as Figure 7.

Two heat dissipation elements 40-1 and 40-2 are arranged on both sides of the light emitting elements 10-1 to 10-3. The heat dissipation element 40 is adhered to the side of the light guide plate 14 by an adhesive member 41. The heat dissipation element 40 is also adhered to the bottom surface of the flexible printed wiring board 11. The other configurations are the same as those in the first embodiment.

According to the second embodiment, the same effect as the first embodiment can be obtained. Furthermore, according to the second embodiment, by arranging the heat dissipation element 40 at the end of the light guide plate 14, the heat dissipation effect from the side surface of the light guide plate 14 in the Y direction can be improved.

The second embodiment may be combined with the first embodiment. That is, a heat dissipation element 40 may be disposed between the multiple light-emitting elements 10, and two heat dissipation elements 40 may be disposed on either side of the multiple light-emitting elements 10.

In each of the above embodiments, a configuration example in which the lighting device 2 includes multiple heat dissipation elements 40 is shown, but the lighting device 2 may be configured to include at least one heat dissipation element 40.

In addition, in each of the above embodiments, a liquid crystal display device is used as an example of a display device, but the lighting device 2 can be applied to display devices other than liquid crystal display devices. Furthermore, this embodiment can be applied to various electronic devices in which the lighting device 2 can be used.

The present invention is not limited to the above-described embodiments, and can be modified in various ways during implementation without departing from the gist of the invention. The embodiments may be implemented in appropriate combination, in which case the combined effects can be obtained. Furthermore, the above-described embodiments include various inventions, and various inventions can be extracted by combinations selected from the multiple constituent elements disclosed. For example, if the problem can be solved and an effect can be obtained even if some constituent elements are deleted from all the constituent elements shown in the embodiments, the configuration from which these constituent elements are deleted can be extracted as an invention.

1...Liquid crystal display device, 2...Illumination device, 3...Liquid crystal display panel, 4...Frame, 5...Lower case, 6...Upper case, 10...Light emitting element, 11...Flexible printed wiring board, 12...Adhesive member, 13...Reflective sheet, 14...Light guide plate, 15...Diffusion sheet, 16, 17...Prism sheet, 21, 22...Substrate, 23, 24...Polarizing plate, 25...Driver, 26...Flexible printed wiring board, 27...Adhesive member, 28...Spacer, 30...Liquid crystal layer, 31...Switching element, 32...Insulating layer, 33...Pixel electrode, 34...Contact plug, 35...Color filter, 36...Black matrix, 37...Common electrode, 40...Heat dissipation element, 41...Adhesive member.

Claims (8)

A flexible printed wiring board;
a first light-emitting element and a second light-emitting element provided on a bottom surface of the flexible printed wiring board, electrically connected to wiring in the flexible printed wiring board, and arranged along a first direction;
a light guide plate disposed to receive light emitted from the first and second light emitting elements at a side surface thereof and configured to emit light from the first and second light emitting elements from an upper surface thereof;
a first heat dissipation element provided on a bottom surface of the flexible printed wiring board, disposed between the first and second light emitting elements, and configured to dissipate heat generated by the first and second light emitting elements ;
a first adhesive member that adheres the first heat dissipation element and the light guide plate;
A display device illumination device comprising: A third light emitting element disposed adjacent to the second light emitting element;
a second heat dissipation element disposed between the second and third light emitting elements and configured to dissipate heat generated by the second and third light emitting elements ;
The display device lighting device according to claim 1 , further comprising a second adhesive member that adheres the second heat dissipation element and the light guide plate to each other. A flexible printed wiring board;
a plurality of light-emitting elements provided on a bottom surface of the flexible printed wiring board, electrically connected to wiring within the flexible printed wiring board, and arranged along a first direction;
a light guide plate that is disposed so as to receive light emitted from the plurality of light-emitting elements at a side surface thereof and that outputs the light from the plurality of light-emitting elements from an upper surface thereof;
a first heat dissipation element provided on a bottom surface of the flexible printed wiring board, disposed on one side of the plurality of light emitting elements, and configured to dissipate heat generated by the plurality of light emitting elements ;
a first adhesive member that adheres the first heat dissipation element and the light guide plate;
A display device illumination device comprising: A second heat dissipation element is disposed on the other side of the plurality of light emitting elements and configured to dissipate heat generated by the plurality of light emitting elements ;
The display device lighting device according to claim 3 , further comprising a second adhesive member that adheres the second heat dissipation element and the light guide plate to each other. The display device lighting device according to claim 1 , further comprising an adhesive member that bonds a part of a bottom surface of the flexible printed wiring board and a part of the light guide plate. The display device lighting device according to claim 1 , wherein the heat dissipation element is a dummy light emitting element. The display device lighting device according to claim 6 , wherein the dummy light emitting element is not electrically connected to wiring within the flexible printed wiring board. A lighting device according to any one of claims 1 to 7,
a display panel that transmits light from the illumination device and displays an image;
A display device comprising: