JP4132854B2 - Direct type backlight - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a backlight for use as a liquid crystal backlight, a light box used for viewing photographic negatives, a shaw casten used for viewing X-ray photographs, a signboard, and the like.
[0002]
[Prior art]
Backlights for liquid crystal display devices and the like are roughly classified into a side type and a direct type based on the arrangement of light sources. In the side type, a light source is arranged on the side of the light guide plate, and in the direct type, a light source is arranged behind (directly below) the diffusion plate serving as a light emitting surface.
[0003]
As shown in FIG. 6, in the case of a backlight 100 for a liquid crystal display device, a case 101, a diffusion plate 102 serving as a light emitting surface, a light source 103 inside the case 101, an inverter 104 to which the light source 103 is connected, and a diffusion plate An optical sheet 105 or the like placed on the surface of 102 is provided.
As the light source 103, a plurality of lamps are generally used in order to obtain high luminance. In the case of a liquid crystal backlight, if the display size is 15 inches, 4 to 8 cold cathode tubes are used. Fluorescent lamps are used, and if it is 20 inches, about 8 to 14 fluorescent lamps are used.
[0004]
[Problems to be solved by the invention]
In the case of the illustrated backlight 100, the light source 103 is disposed so as to be surrounded by the case 101 and the diffusion plate 102, so that heat is easily trapped inside the case 101 due to heat generated from the light source 103.
[0005]
In addition, the fluorescent lamp as the light source 103 has a characteristic that waste energy is consumed as heat generation in the electrode and the vicinity of the electrode becomes hot because the conversion efficiency from electric energy to light is low in the vicinity of the electrode. In particular, in the case of a cold cathode tube, the light conversion efficiency in the vicinity of the electrode is lower than that in the hot cathode tube, so that heat generation is large and the temperature in the vicinity of the electrode may be about 100 ° C.
The inverter 104 for lighting the fluorescent lamp also generates a large amount of heat in terms of its function.
[0006]
For this reason, the temperature inside the case 101 of the backlight rises due to heat generated from the electrodes of the light source 103 and the inverter 104, and it has been confirmed by experiments that the temperature inside the case 101 rises to nearly 60 ° C.
And when the temperature inside case 101 rises, the luminous efficiency of light source 103 will fall and the problem that the brightness | luminance of a backlight will fall will generate | occur | produce. Therefore, it is desirable that the temperature in the vicinity of the light source 103 is kept relatively low (for example, about 40 ° C.).
[0007]
Here, as means for lowering the temperature inside the case 101 which has become too hot, it is conceivable that 1) an air hole or a fan is provided in the case for cooling, and 2) a cooling fin is provided in the case 101.
However, the means 1) has a drawback that the air around the light source is replaced by an air hole or a fan, so that the temperature in the vicinity of the light source changes abruptly and the brightness fluctuates (becomes up and down) due to the rapid change in temperature. In addition, if the air hole is formed large in order to increase the efficiency of replacing air, it is easy for foreign matter to enter from the outside, resulting in deterioration of light emission quality such as a decrease in brightness.
[0008]
Further, in the means of 2), even if fins are provided, the cooling efficiency is small compared to the means of 1), and in order to increase the cooling efficiency, a large fin is required, the product size increases and the weight increases. Leads to an increase in size.
The present invention has been made in view of such a problem, and an object thereof is to provide a new means for preventing a decrease or change in luminance due to heat of a direct type backlight.
[0009]
[Means for Solving the Problems]
In the present invention, a tubular lamp comprising a cold cathode tube having electrodes at both ends in a longitudinal direction is disposed in a case having a non-light emitting region around a light emitting surface portion, and a direct type having an inverter for lighting the tubular lamp. In the case, the backlight includes a heat shielding plate that divides a first space mainly behind the light emitting surface portion and a second space mainly behind the non-light emitting region in the case, and the inverter The tubular lamp is housed in the second space, and the electrode portions at both ends in the longitudinal direction of the tubular lamp are located in the second space, and the midway portion in the longitudinal direction is located in the first space. It is characterized by that.
[0010]
According to the present invention, the first space is partitioned by the heat shield plate with respect to the second space where the inverters that are heat sources and the electrode portions at both ends of the tubular lamp are located. For this reason, the first space is a space that is less affected by heat generated from the inverter and the electrodes. Further, the midway portion in the longitudinal direction, which is the effective light emitting portion of the tubular lamp, is located in the first space where there is little influence of heat generation, so that the temperature rise in the vicinity of the tubular lamp effective light emitting portion is small, and the brightness of the tubular lamp A decrease in height is prevented.
[0011]
Moreover, it is preferable that the case has an air communication portion that communicates from the second space to the outside of the case. The second space in which the inverter and the tubular lamp electrode are located communicates with the outside of the case through the air communication portion, so that the air is exchanged between the second space and the outside of the case, and the second space is efficiently cooled. Is done. Moreover, even if the second space is rapidly cooled by the replacement of air, it is separated from the first space where the middle part of the tubular lamp is located by the heat shield, so that a sudden temperature change in the first space. Is prevented, and a change in the brightness of the tubular lamp is prevented. Furthermore, even when foreign matter such as dust enters the case from the outside of the case through the air communication portion, the presence of the heat shield plate can suppress the entry of foreign matter into the first space, so that the air communication portion is enlarged. Can take.
[0012]
Further, in the present invention, it is preferable that a light reflecting portion is provided on the surface of the heat shield plate on the first space side. In this case, even if the heat shield plate is provided, the light emitting quality of the light emitting surface portion is improved. Decline can be prevented.
[0013]
The heat shield plate is preferably located on the light emitting surface portion side from the boundary between the light emitting surface portion and the non-light emitting region, and divides the first space and the second space. Can be taken widely. In addition, since the reflective portion is provided on the surface of the heat shield plate on the first space side, the effective light emitting area in the light emitting surface portion can be widened even if the heat shield plate is located on the light emitting surface portion side.
[0014]
In the present invention, it is preferable that all the ineffective light emitting portions in the vicinity of both ends in the longitudinal direction of the tubular lamp are stored in the second space. In this case, only the effective light emitting portion of the tubular lamp is located in the first space. In addition, the dark ineffective light emitting portion is not visible from the light emitting surface portion side, and uniform light emission quality is ensured.
[0015]
Further, the case is configured such that a second case body provided with a light emitting surface portion is detachably attached to a first case body provided with a light source, and the heat shield is provided on the second case body. In this case, when the second case body is removed from the first case body, the heat shield plate is also removed together with the second case body, and the first space and the second space are separated inside the first case body. Thus, maintenance such as replacement of a tubular lamp located across the first space and the second space can be easily performed.
[0016]
Further, the heat shield plate extends from the second case body toward the first case, and the first space and the first case are between the heat shield plate in the extending direction and the first case body. It is preferable that a gap that allows air to flow between the two spaces is formed. In this case, some air flows between the first space and the second space through the gap, and the temperature in the entire case is made uniform. And it is preferable that the space | interval of this clearance gap is 10 mm or less in order to suppress the rapid temperature change of 1st space, and the foreign material approach to 1st space.
[0017]
The present invention is a direct type backlight in which a tubular lamp made of a cold cathode tube having electrode portions at both ends in the longitudinal direction is disposed in a case having a non-light emitting region around the light emitting surface portion. And a heat shield that mainly separates the first space behind the light emitting surface portion and the second space behind the non-light emitting region, and the tubular lamp has electrode portions at both ends in the longitudinal direction. While being located in the said 2nd space, a longitudinal direction middle part shall be located in the said 1st space. In this case, a decrease in the brightness of the tubular lamp due to heat generated by the electrodes at both ends of the tubular lamp located in the second space is prevented.
[0018]
Furthermore, in the present invention, a light source comprising a cold-cathode tube is disposed in a case having a non-light-emitting region around the light-emitting surface portion, and is a direct type backlight including an inverter for turning on the light source. A heat shield that divides the first space mainly behind the light emitting surface portion and the second space mainly behind the non-light emitting area, and the inverter is housed in the second space. It can be assumed that In this case, the brightness of the tubular lamp is prevented from being reduced due to heat generated by the inverter located in the second space.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the present embodiment, a description will be given by taking a Schaukasten for observing an X-ray photograph or the like as an example of a direct type backlight. 1 to 4 includes a case 2 formed in a thin box shape having a thickness of 60 mm or less, and the case 2 includes a diffusion plate 3 serving as a light emitting surface portion. The thickness of the case 2 is specifically 40 mm. Inside the case 2, a light source 4 and an inverter 5 are provided. The upper side of FIG. 3 is expressed as “upper” of the shaukasten 1, and the lower side of FIG. 3 is expressed as “lower” of the shaukasten 1. However, these expressions are for convenience, and the upper and lower sides are horizontally oriented. It does not limit the way of installing the shaukasten 1 or the like.
[0020]
The case 2 includes a first case body 7 serving as a lower case and a second case body 8 serving as an upper case. The first case body 7 has a rectangular bottom surface 7a and a side surface 7b erected upward from the periphery of the bottom surface 7a, and is formed in an upper opening shape. A through hole communicating with the inside and outside of the case is formed on the side surface 7b of the first case body 7, and this through hole is an air communication portion 7c for allowing air to flow inside and outside the case.
The second case body 8 has a frame-shaped upper surface 8a and a side surface 8b provided to hang from the outer peripheral edge of the upper surface 8a. It is fixed with. Since the first case body 7 and the second case body 8 are screw-fixed, they can be easily separated, and maintenance or the like can be easily performed by removing the second case body that is the upper case. The first case body 7 and the second case body 8 are both made of metal.
[0021]
A concave portion 10 into which the peripheral edge of the rectangular diffusion plate 3 is inserted is formed in the inner peripheral portion of the frame of the second case body 8. The diffusion plate 3 is inserted into the recess 10 and is fixed to the second case body 8 with screws 10a. By attaching the diffusion plate 3 to the inner peripheral side of the second case body 8, the second case body 8 is positioned in a frame shape around the diffusion plate 3 as shown in FIG. 1. Further, a clip part 11 for fixing the X-ray photograph is provided on one long side part (the upper long side part in FIG. 1) of the rectangular frame-shaped second case body 8. The X-ray photograph can be fixed to the shaucus ten 1 by inserting the X-ray photograph between the diffusing plate 3 and the diffusion plate 3.
[0022]
Due to the presence of the second case body 8 and the clip portion 11, the light emitting surface portion 3 a that actually emits light of the diffusion plate 3 is a portion where the diffusion plate 3 is inserted into the recess 10 and a portion hidden by the clip portion 11. (The range in which the diffusion plate 3 can be seen in FIG. 1), and the light emitting surface portion 3a emits light by the light from the light source 4. On the other hand, a portion surrounding the light emitting surface portion 3a in a frame shape by the second case body 8 and the clip body 11 is an ineffective light emitting region that does not emit light.
[0023]
The diffusion plate 3 is formed of a white transparent acrylic plate, and diffuses light from the light source 4 to form a uniform light emitting surface. The light emitting surface portion 3a has a length in the horizontal length direction of 1141.2 mm, a length in the vertical width direction of 431.3 mm, and the X-ray photograph (X-ray film) of a half-cut size in the horizontal direction in the vertically long state. The size is approximately equivalent to that of three (multiple) X-ray photographs of half-cut size so that three (multiple) sheets can be placed on each other. The size of the half-cut X-ray photograph is 356 × 432 mm. Further, the size of the X-ray photograph of the large angle size is 356 × 356 mm, and the size of the X-ray photograph of the continental (large square cut) size is 279 × 356 mm. If it is a X-ray photograph of a continent size, four sheets can be arranged in the light emission surface part 3a.
[0024]
On the bottom surface 7a of the first case body 7, a reflecting plate 13 for reflecting light from the light source 3 is disposed. The reflecting plate 13 is made of a metal plate painted white in order to reflect light efficiently and uniformly. The reflection plate 13 is formed to be substantially the same size as the continent-size X-ray photograph, and four (a plurality of) are arranged in parallel in the horizontal direction. The four corners of each reflector 13 are detachably attached to the first case body 7 by screws 14 respectively.
[0025]
Six (a plurality) of light sources 4 are provided on these reflectors 13, respectively, and a total of 24 (6 × 4) light sources 4 are provided in the entire shaucus ten 1. As shown in FIG. 5, the light source 4 is a tubular lamp having electrode portions 16 and 16 at both ends in the longitudinal direction, and is specifically a cold cathode fluorescent lamp. The tubular lamp may be a hot cathode tube, but the tube diameter can be reduced by using a cold cathode tube. As the cold cathode tube 4, a thin tube type having a tube diameter φ of about 2 to 6 mm is used, and the thickness of the shaucus ten 1 is reduced.
[0026]
The vicinity of both end portions in the longitudinal direction including the electrode portion 16 of the cold cathode tube 4 is an ineffective light emitting portion 17 having low brightness even during lighting, and the cold cathode tube 4 sandwiched between the ineffective light emitting portions 17 and 17. In the middle in the longitudinal direction, a bright effective light emitting portion 18 is formed. Note that the length of the ineffective light emitting portion is about several mm.
[0027]
As shown in FIG. 3, holding rubber 20 is attached to both ends of the tubular lamp 4 in the longitudinal direction so as to cover the electrode portion 16. The holding rubber 20 is attached to a lamp mounting portion 21 provided on the reflection plate 13 to position and fix the tubular lamp 4 to the reflector 13. The tubular lamp 4 is held by the holding rubber 20 in a state of being floated from the reflector 13, and current leakage from the tubular lamp 4 to the metal reflector 13 is prevented and the light emission quality is secured. The distance between the tubular lamp 4 and the reflector 13 is about 1.9 mm.
[0028]
The holding rubber 20 is made of flame retardant silicon rubber, and also functions as a protective member when the electrode portion 16 reaches a high temperature exceeding 100 ° C. Further, since the holding rubber 20 is also an insulating material, it functions as an insulating body that is positioned between the tubular lamp 4 through which a current flows and the metallic reflector 13 for insulation.
[0029]
Four (a plurality) of inverters 5 are provided in the first case body 7. Each inverter is arranged below the upper surface 8a of the second case body in FIG. 3 so as to be located behind the ineffective light emitting region of the case. Each inverter is provided in a number (four) corresponding to the reflectors 13, and one inverter 5 is connected to a plurality of light sources 4 provided on one reflector 13. In the shaw casten 1, the light source 4 can be turned on / off for each reflector 13 by turning each inverter on / off.
[0030]
Each inverter 5 is arranged at a predetermined distance from the side surface 7 b of the first case body 7. A space 23 between the inverter 5 and the side surface 7b is used for passing wiring for supplying electricity to the inverter. Further, the space 23 ensures insulation between the inverter 5 and the first case body 7. Further, the space 23 promotes heat dissipation of the inverter 5. The distance between the inverter 5 and the side surface 7b is about 5 to 12 mm. For convenience of arrangement, the inverters 5 are distributed on the side surface 7b on the one side in the longitudinal direction of the light source 4 and the side surface 7b on the other side (see FIG. 1).
[0031]
The inverter 5 is configured by mounting a circuit component 26 such as a transformer or a capacitor on an elongated circuit board 25, and is arranged vertically so that the circuit board 25 is parallel to the side surface 27. The vertical arrangement can save space compared to the case where the circuit board 25 is arranged flat so that the circuit board 25 is parallel to the bottom surface 7a. In addition, heat dissipation is better when placed vertically than when placed horizontally.
[0032]
The second case body 8 which is the upper case is provided with a heat shield plate 28 for dividing the case internal space. The heat shield plate 28 is made of metal, is attached to the back surface 8c of each long side portion of the rectangular frame-shaped second case body, and is behind the light emitting surface portion 3a (downward in FIG. 3). 29 is separated from the second space 30 behind (below in FIG. 3) the non-light emitting region (second case body upper surface 8 a) on both ends in the longitudinal direction of the tubular lamp 4.
[0033]
The heat shield plate 28 is fixed to the second case body 8 by screws 10 c on the back surface 8 c of the second case body 8. The diffusion plate 3 is also fixed to the second case body 8 by screws 10c that fix the heat shield plate 28. Since the heat shield 28 is provided in the second case body 8, when the second case body 8 is removed, the first case 29 is not separated from the first space 29 and the second space 30, and maintenance is facilitated. It is easy to replace the light source.
The heat shield plate 28 extends downward from the second case body 8 toward the first case body 7. Moreover, the heat shield plate 28 is inclined obliquely downward so as to go from the boundary 32 between the light emitting surface portion 3a and the non-light emitting region toward the longitudinal center of the tubular lamp 4 (right side in FIG. 3). Therefore, the heat shield plate 28 is located closer to the light emitting surface portion 3a than the boundary 32 between the light emitting surface portion 3a and the non-light emitting region.
[0034]
The both ends in the longitudinal direction of the tubular lamp 4 are not in the non-light emitting region but behind the light emitting surface portion 3a, but the heat shield plate 28 is inclined so that the vicinity of both ends in the longitudinal direction of the tubular lamp 4 is Located in the second space 30. The range of about 8 mm from the end in the longitudinal direction of the tubular lamp 4 is located in the second space 30. As a result, not only the ineffective light emitting portion 17 of the tubular lamp 4 but also a part of the effective light emitting portion 18 adjacent to the ineffective light emitting portion 17 is located in the second space 30. Since the ineffective light emitting portion 17 is located in the second space 30, only the effective light emitting portion 18 of the tubular lamp 4 is in the first space 29, and the dark ineffective light emitting portion 17 from the light emitting surface portion 3a side. Disappears and the luminous quality improves.
[0035]
In addition, since the surface of the metal heat shield plate 28 facing the first space 29 is painted white to form the light reflecting portion 33, the brightness of the area where the heat shield plate 28 is provided is also ensured. Even if the heat shield plate 28 is provided, the light emitting surface portion 3a can be secured widely.
The heat shield plate 28 may be made of resin, and in this case, a heat shield plate having a reflection portion can be obtained by using a white resin or a white painted resin.
[0036]
The inclination angle α of the heat shield plate 28 with respect to the case thickness direction is preferably 45 ° or less, and is set to 45 ° in this embodiment. By setting the inclination angle α to 45 ° or less, the light of the effective light emitting portion 18 of the tubular lamp 4 easily reaches the entire reflecting portion 33, and the light uniformity is ensured. Further, the heat shield plate 28 is bent so that the angle with respect to the case thickness direction becomes small at the middle portion 34 in the downward extending direction, and the tubular lamp 4 is formed in the first position while avoiding interference with the lamp mounting portion 21 and the like. The range located in the two spaces 30 is reduced.
[0037]
In order to avoid interference with the tubular lamp 4, the lower end 36, which is the front end in the extending direction of the heat shield plate 28, is formed with a notch 36 a in a portion corresponding to the tubular lamp 4, and the tubular lamp 4 is formed by the heat shield plate 28. Damage is prevented. Further, the portion of the lower end 36 of the heat shield plate 28 which is not the notch 36a is in a floating state without being in contact with the reflector plate 13, and the tubular reflector plate 13 is prevented from being damaged by the heat shield plate 28. As a result, the light emission quality is prevented from being deteriorated due to damage to the reflector 13.
[0038]
In addition, air flow between the first space 29 and the second space 30 is ensured by the gap 37 between the lower end 36 and the reflecting plate 13 (first case body bottom surface 7a). The gap 37 between the lower end 36 and the reflecting plate 13 is preferably 10 mm or less in order to avoid a temperature rise in the first space 29 due to a large amount of hot air flowing into the first space 29. .5 mm. Further, if a large or large number of through holes, which are the air communication portions 7c, are formed to facilitate the replacement of air in the second space 30, foreign matter can easily enter the case 2, but the interval between the gaps 37 can be reduced. Thus, entry of foreign matter into the first space 29 is prevented.
[0039]
According to the present embodiment, the tubular lamp electrode portion 16 and the inverter 5 that generate heat are housed in the second space 30 surrounded by the first case body 7, the second case body 8, and the heat shield plate 33, Since the effective light emitting part 18 of the tubular lamp 4 in the one space 29 is shielded from heat, the luminance of the effective light emitting part 18 is unlikely to decrease. Moreover, since the air communication between the second space 29 and the outside of the case is ensured by the air communication portion 7c of the first case body 7, the inside of the second space 30 is efficiently cooled by replacing the air from the outside of the case. At the same time, the temperature change in the second space 30 is not easily transmitted to the first space 29 due to the presence of the heat shield plate 28. As a result, there is no rapid temperature change in the vicinity of the effective light emitting portion 18 of the tubular lamp 4, and a change in brightness (flicker) is prevented. In the case of shaukasten, the change in brightness (flicker) prevents accurate interpretation of the X-ray photographic film, but according to the present embodiment, accurate diagnostic information can be obtained due to the stability of the brightness.
[0040]
In addition, this invention is not limited to the said embodiment, A various change is possible within the range of the matter described in the claim. For example, the application example as a backlight is not limited to the Schaukasten, and the same configuration can be adopted for a backlight for a liquid crystal display device or the like. Regarding the invention according to some claims, only one of the electrode of the tubular lamp and the inverter may be located in the second space. In addition, when not providing an inverter in 2nd space, you may arrange | position an inverter not only in a case but out of a case.
[0041]
【The invention's effect】
According to the present invention, the midway portion in the longitudinal direction, which is the effective light emitting portion of the tubular lamp, is partitioned by the heat shield and located in the first space where the influence of heat generation is small. The temperature rise is small, and the brightness of the tubular lamp is prevented from being lowered.
[Brief description of the drawings]
FIG. 1 is a plan view of a backlight (Shaukasten). FIG. 2 is a side view of the backlight (Shaukasten) (viewed in the direction of arrow II in FIG. 1).
FIG. 3 is a partial cross-sectional view (III-III cross-sectional view of FIG. 1) of a backlight (Shawkasten).
FIG. 4 is a partial plan view of a second case body and a heat shield plate excluding a diffusion plate.
FIG. 5 is an explanatory diagram of an ineffective light emitting part and an effective light emitting part of a cold cathode tube.
FIG. 6 is a schematic configuration diagram of a conventional backlight.
[Explanation of symbols]
1 Schaukasten (Backlight)
2 Case 3a Light emitting surface 4 Light source (tubular lamp; cold cathode tube)
5 Inverter 7 First case body 7c Air communication part 8 Second case body 16 Electrode part 17 Non-effective light emitting part 18 Effective light emitting part 28 Heat shield plate 29 First space 30 Second space 32 Boundary 33 Reflecting part 36 Heat shield plate Bottom 37 gap

Claims (10)

This is a direct type backlight provided with a tubular lamp composed of a cold cathode tube having electrodes at both ends in the longitudinal direction in a case having a non-light emitting region around the light emitting surface portion, and having an inverter for lighting the tubular lamp. In the case, a heat shielding plate is provided that divides a first space mainly behind the light emitting surface portion and a second space mainly behind the non-light emitting region, and the inverter includes the second space. The tubular lamp is housed in a space, and the electrode portions at both ends in the longitudinal direction are respectively located in the second space, and the midway portion in the longitudinal direction is located in the first space. Direct type backlight.   The direct type backlight according to claim 1, wherein an air communication portion communicating from the second space to the outside of the case is formed in the case.   3. The direct type backlight according to claim 1, wherein a light reflecting portion is provided on a surface of the heat shield plate on the first space side.   4. The direct back according to claim 3, wherein the heat shield plate is positioned closer to the light emitting surface portion than the boundary between the light emitting surface portion and the non-light emitting region, and divides the first space and the second space. Light.   5. The direct type backlight according to claim 3, wherein all the ineffective light emitting portions in the vicinity of both ends in the longitudinal direction of the tubular lamp are accommodated in the second space.   The case includes a first case body provided with a tubular lamp, and a second case body provided with a light emitting surface portion being detachably attached, and the heat shield is provided on the second case body. The direct type backlight according to any one of claims 1 to 5.   The heat shield plate extends from the second case body toward the first case, and the first space and the second space are provided between the end of the heat shield plate in the extending direction and the first case body. The direct-type backlight according to claim 6, wherein a gap is formed to allow air to flow there between.   The direct type backlight according to claim 7, wherein the gap is 10 mm or less. A direct type backlight in which a tubular lamp made of a cold cathode tube having electrodes at both ends in a longitudinal direction is disposed in a case having a non-light emitting region around a light emitting surface portion, and the light emitting surface portion mainly in the case A heat shield that separates the first space behind the second space mainly behind the non-light-emitting region, and the tubular lamp has electrode portions at both ends in the longitudinal direction in the second space. A direct type backlight characterized by being located and having a midway portion in the longitudinal direction located in the first space. A light source comprising a cold cathode tube is disposed in a case having a non-light emitting area around the light emitting surface portion, and is a direct type backlight provided with an inverter for turning on the light source. A heat shield is provided to partition a first space behind the light emitting surface portion and a second space mainly behind the non-light emitting area, and the inverter is housed in the second space. Direct type backlight.

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