JP2003234012A - Over head backlight - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new means for preventing the degradation or variation in intensity by heat of an overhead backlight. <P>SOLUTION: In the overhead backlight, a tubular lamp 4 having electrodes 16 at both longitudinal ends is disposed in a case 2 having a non-light emitting area 8a around a light-emitting surface part 3a, and an inverter 5 for turning on the tubular lamp 4 is provided. In the case 2, a heat shield plate 28 is provided which divides a first space 29 mainly behind the light-emitting surface 3a from a second space 30 mainly behind the non-light emitting area 8a. The inverter 5 is provided in the second space 30, and in the tubular lamp 4, each of the electrodes 16 at the longitudinal both ends is located in the second space 30, and a longitudinal middle part 18 is located in the first space 29. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal backlight, a light box used for viewing a negative of a photograph, a Schaukasten used for viewing an X-ray photograph, a backlight used as a signboard, and the like. is there.

[0002]

2. Description of the Related Art Backlights for liquid crystal display devices are
It is roughly divided into a side type and a direct type according to the arrangement of the light sources. The side type has a light source arranged on a side portion of a light guide plate, and the direct type has a light source arranged behind (immediately below) a diffusion plate which is a light emitting surface.

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, and an inverter 104 to which the light source 103 is connected. , Diffusion plate 102
The optical sheet 105 and the like placed on the surface of the sheet. As the light source 103, in order to obtain high brightness,
It is common to use a plurality of lamps. In the case of a backlight for liquid crystal, a fluorescent lamp consisting of 4 to 8 cold cathode tubes is used if the display size is 15 inches, and if it is 20 inches. About 8 to 14 fluorescent lamps are used.

[0004]

The backlight 1 shown in the figure.
In the case of 00, the light source 103 includes the case 101 and the diffusion plate 10.
Since it is surrounded by 2 and is arranged, heat is easily accumulated inside the case 101 due to heat generated from the light source 103.

Moreover, the fluorescent lamp as the light source 103 is
Since the conversion efficiency of electric energy into light is low near the electrodes, there is a characteristic that wasteful energy is consumed as heat generation in the electrodes and the vicinity of the electrodes becomes hot. Particularly, in the case of a cold cathode tube, since the light conversion efficiency in the vicinity of the electrode is lower than that in the hot cathode tube, heat generation is large and the temperature in the vicinity of the electrode may reach about 100 ° C. In addition, the inverter 104 for lighting the fluorescent lamp also has
Fever is large.

Therefore, the backlight case 101 is generated by heat generated from the electrodes of the light source 103 and the inverter 104.
The internal temperature rises, and experiments have confirmed that the internal temperature of the case 101 rises to nearly 60 ° C.
Then, when the temperature inside the case 101 rises, the light source 1
03, the luminous efficiency is lowered, and the brightness of the backlight is lowered. Therefore, it is desirable that the temperature in the vicinity of the light source 103 is kept relatively low (eg, about 40 ° C.).

Here, as means for lowering the temperature inside the case 101 that has become too hot, 1) providing air holes or a fan in the case for cooling, and 2) providing cooling fins in the case 101 are conceivable. . However, in the method of 1), since the air around the light source is replaced by the air holes and the fan, the temperature near the light source changes abruptly, and the brightness fluctuates (rises and falls) due to the abrupt temperature change.
Moreover, if the air holes are formed to be large in order to increase the efficiency of air exchange, foreign matter can easily enter from the outside, which causes deterioration in light emission quality such as a decrease in brightness.

Further, in the means of 2), even if the fins are provided, the cooling efficiency is smaller than that of the method of 1), and in order to increase the cooling efficiency, a large fin is required, resulting in an increase in product size and weight. It leads to larger size such as larger size. The present invention has been made in view of the above problems, and an object of the present invention is to provide new means for preventing a decrease or a change in luminance due to heat of a direct type backlight.

[0009]

According to the present invention, a tubular lamp having electrode portions at both longitudinal ends is arranged in a case having a non-light emitting area around a light emitting surface portion, and an inverter for lighting the tubular lamp is provided. A direct type backlight provided with a heat shield plate for partitioning a first space mainly behind the light emitting surface portion and a second space mainly behind the non-light emitting region in the case. The inverter is housed in the second space, and the tubular lamp has electrode portions at both ends in the longitudinal direction located in the second space, and an intermediate portion in the longitudinal direction in the first space. It is characterized by being located.

According to the present invention, the first space is the second space where the inverters which are heat sources and the electrode parts at both ends of the tubular lamp are located.
The space is separated by a heat shield. Therefore, the first space is a space that is less affected by the heat generated from the inverter and the electrodes. In addition, the middle portion in the longitudinal direction, which is the effective light emitting portion of the tubular lamp, has the first effect that heat generation is small.
Since it is located in the space, the temperature in the vicinity of the effective light emitting portion of the tubular lamp does not rise so much that the brightness of the tubular lamp is prevented from decreasing.

Further, it is preferable that an air communication portion is formed in the case so as to communicate with the outside of the case from the second space. Second place where the inverter and tubular lamp electrode are located
Since the space communicates with the outside of the case by the air communication portion, the air is exchanged between the second space and the outside of the case, and the second space is efficiently cooled. Moreover, even if the second space is rapidly cooled by the exchange of air, it is separated from the first space in which the tubular lamp middle part is located by the heat shield plate, so that the rapid temperature change in the first space is caused. And the brightness of the tubular lamp is prevented from changing. Furthermore, even if foreign matter such as dust enters the case from the outside of the case through the air communication part,
Due to the presence of the heat shield, foreign matter can be prevented from entering the first space, so that the air communication portion can be made large.

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 side of the first space, and in this case, even if the heat shield plate is provided, the light emitting surface portion is It is possible to prevent deterioration of light emission quality.

Further, it is preferable that the heat shield plate is located on the light emitting surface portion side of the boundary between the light emitting surface portion and the non-light emitting area and separates the first space and the second space. In this case,
The second space can be wide. Moreover, since the reflecting portion is provided on the surface of the heat shield plate on the side of the first space, even if the heat shield plate is located on the light emitting surface portion side, the effective light emitting area in the light emitting surface portion can be widened.

In the present invention, it is preferable that all the ineffective light emitting portions near both ends in the longitudinal direction of the tubular lamp are housed in the second space. In this case, the effective light emitting portion of the tubular lamp is contained in the first space. However, the dark non-effective light emitting portion cannot be seen from the light emitting surface portion side, and uniform light emitting quality is secured.

Further, the case is constructed by detachably attaching a second case body having a light emitting surface portion to a first case body having a light source, and the heat shield plate is provided on the second case body. It is preferably provided, and 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 case body, so that there is no separation between the first space and the second space inside the first case body.
Maintenance such as replacement of the tubular lamp located over the first space and the second space can be easily performed.

The heat shield plate is extended from the second case body toward the first case, and the first space is provided between the extension direction end of the heat shield plate and the first case body. And the second
It is preferable that a gap is formed to allow air to flow between the space. 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, the interval of this gap is the first
It is preferably 10 mm or less in order to prevent a rapid temperature change in the space and the entry of foreign matter into the first space.

Further, the present invention is a direct type backlight in which tubular lamps having electrode portions at both longitudinal ends are arranged in a case having a non-light emitting region around a light emitting surface part, and A first space behind the light emitting surface portion and a second space mainly behind the non-light emitting area.
The tubular lamp is provided with a heat shield plate that separates the space from each other, and the tubular lamp has electrode portions at both ends in the longitudinal direction located in the second space, and an intermediate portion in the longitudinal direction located in the first space. Can be one. In this case, it is possible to prevent the brightness of the tubular lamp from being lowered due to heat generated by the electrodes on both ends of the tubular lamp located in the second space.

Further, according to the present invention, there is provided a direct type backlight in which a light source is arranged in a case having a non-light emitting area around a light emitting surface and an inverter for turning on the light source is provided. And a heat shield plate 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 is housed in the second space. Can be. In this case, the brightness of the tubular lamp is prevented from decreasing due to the heat generated by the inverter located in the second space.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In the present embodiment, a Schaukasten for observing an X-ray photograph or the like will be described as an example of a direct type backlight. The Schaukasten 1 shown in FIGS. 1 to 4 has a case 2 formed in a thin box shape having a thickness of 60 mm or less. The case 2 is provided with 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. It should be noted that the upper side of FIG. 3 is expressed as “upper” of the Schaukasten 1 and the lower side of FIG. 3 is expressed as “lower” of the Schaukasten 1. However, these expressions are for convenience, and the upper and lower sides are expressed horizontally. It does not limit how to install the Schaukasten 1.

The case 2 is provided with 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 provided upright from the peripheral edge of the bottom surface 7a, and is formed in an upper opening shape. A through hole that communicates 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 serves as an air communicating portion 7c for allowing air to flow inside and outside the case. The second case body 8 has a frame-shaped upper surface 8 a and a side surface 8 b that is provided so as to hang down from the outer peripheral edge of the upper surface 8 a, and is externally fitted from the upper portion of the first case body 7, and the screw 9 Fixed by. Since the first case body 7 and the second case body 8 are of a screw fixing type, they can be easily separated, and maintenance and the like can be easily performed by removing the second case body which is the upper case. The first case body 7 and the second case body 8 are both made of metal.

A recess 10 into which the peripheral edge of the rectangular diffusion plate 3 is inserted is formed on the inner peripheral portion of the frame of the second case body 8. The diffusion plate 3 is inserted into the recess 10 and fixed to the second case body 8 with the screw 10a. The diffusion plate 3 is attached to the second case body 8
By mounting the second case body 8 on the inner peripheral side, the second case body 8 is frame-shaped around the diffusion plate 3 as shown in FIG.
In addition, one long side portion of the second case body 8 having a rectangular frame shape (see FIG.
In the upper long side in FIG. 1, a clip portion 11 for fixing the X-ray photograph is provided, and the X-ray photograph is inserted between the clip portion 11 and the diffusion plate 3 so that the X-ray photograph can be sandwiched. The photo can be fixed on the Schaucasten 1.

Due to the presence of the second case body 8 and the clip portion 11, the light emitting surface portion 3a of the diffusion plate 3 which actually emits light.
Is an area excluding a portion where the diffusion plate 3 is inserted into the recess 10 and a portion hidden by the clip portion 11 (see FIG. 1).
In the area where the diffusion plate 3 can be seen), and the light emitting surface 3a
Emits light from the light source 4. On the other hand, the portion surrounding the light emitting surface 3a in a frame shape by the second case body 8 and the clip body 11 is an ineffective light emitting region where no light is emitted.

The diffusion plate 3 is formed of a white transparent acrylic plate and diffuses the light from the light source 4 to form a uniform light emitting surface. Further, the light emitting surface portion 3a has a length in the horizontal and longitudinal directions of 1141.2 mm and a length in the vertical and horizontal directions of 4 mm.
It is 31.3 mm, and it is roughly divided into three half-size X-ray photographs (plural sheets) so that half-size X-ray photographs (X-ray film) can be placed in the horizontal direction in three sheets (plural sheets). It is formed in a corresponding size. In addition, half-size X
The size of the line photograph is 356 × 432 mm. Also,
The size of a large-angle X-ray photograph is 356 x 356 mm, and the size of a continental (large quartered) X-ray photograph is 2.
It is 79 × 356 mm. If it is a continent-size X-ray photograph, four sheets can be arranged on the light emitting surface portion 3a.

A reflecting plate 13 for reflecting the light from the light source 3 is arranged on the bottom surface 7a of the first case body 7.
The reflection plate 13 is composed of a white-painted metal plate in order to reflect light efficiently and uniformly. The reflection plate 13 is formed to have substantially the same size as a continental X-ray photograph, and four sheets (plural sheets) are arranged side by side in the lateral direction. The four corners of each reflector 13 are detachably attached to the first case body 7 by screws 14.

Six light sources 4 (a plurality of light sources) are provided on each of the reflectors 13, and a total of 24 light sources 4 (6 × 4) are provided in the entire Schaukasten 1. Light source 4
5, as shown in FIG.
6 is a tubular lamp, specifically a cold cathode fluorescent lamp. A hot cathode tube may be used as the tubular lamp,
By using a cold cathode tube, the tube diameter can be reduced. 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 Schaukasten 1 is made thin.

In the vicinity of both ends in the longitudinal direction including the electrode portion 16 of the cold cathode tube 4, there is an ineffective light emitting portion 17 having a low brightness even at the time of lighting, and the cold light sandwiched between the ineffective light emitting portions 17, 17. A bright effective light emitting portion 18 is formed in the middle of the cathode tube 4 in the longitudinal direction. The length of the ineffective light emitting part is several meters.
It is about m.

As shown in FIG. 3, holding rubbers 20 are attached to both ends of the tubular lamp 4 in the longitudinal direction so as to cover the electrode portions 16. The holding rubber 20 is attached to the lamp mounting portion 21 provided on the reflection plate 13 to fix the tubular lamp 4 to the reflector 13.
It is for positioning and fixing to. The tubular lamp 4 is held in a state of being floated from the reflector 13 by the holding rubber 20, so that the leakage of current from the tubular lamp 4 to the metallic reflector 13 is prevented and the emission quality is ensured.
The distance between the tubular lamp 4 and the reflector 13 is about 1.9 mm.
Is.

The holding rubber 20 is made of flame-retardant silicone rubber, and also functions as a protective member when the electrode portion 16 reaches a high temperature exceeding 100.degree. Further, since the holding rubber 20 is also an insulating material, it also functions as an insulator which is located between the tubular lamp 4 through which the current flows and the metallic reflector 13 to insulate.

The four inverters 5 are provided in the first case body 7. Each inverter is arranged below the second case body upper surface 8a in FIG. 3 so as to be located behind the ineffective light emitting region of the case. Each inverter is provided by the number (4) corresponding to the reflector 13, and one inverter 5 is connected to each of the plurality of light sources 4 provided in one reflector 13. In this Schaukasten 1, ON / OFF of each inverter
The light source 4 can be turned on and off for each reflector 13.

Each inverter 5 is arranged with a predetermined distance from the side surface 7b of the first case body 7. The space 23 between the inverter 5 and the side surface 7b is used to pass a wire for supplying electricity to the inverter. In addition, the space 23 ensures the 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 arranged in a distributed manner on the side surface 7b on one side and the side surface 7b on the other side in the longitudinal direction of the light source 4 (see FIG. 1).

The inverter 5 is constructed 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 saves space compared to the case where the circuit board 25 is placed horizontally so that the circuit board 25 is parallel to the bottom surface 7a. Also, when placed vertically, the heat dissipation is better than when placed horizontally.

The second case body 8 as the upper case is provided with a heat shield plate 28 for partitioning the case internal space. The heat shield plate 28 is made of metal and has a rectangular frame-like shape.
The first space 29 is attached to the back surface 8c of each long side portion of the case body and is behind the light emitting surface portion 3a (downward in FIG. 3), and the non-light emitting areas (second area) on both ends in the longitudinal direction of the tubular lamp 4 (second area). It separates from the second space 30 behind the case body upper surface 8a) (downward in FIG. 3).

The heat shield plate 28 is a rear surface 8c of the second case body 8.
In, it is fixed to the second case body 8 with the screw 10c. The diffusion plate 3 is also fixed to the second case body 8 by a screw 10c that fixes the heat shield plate 28. Second
Since the case body 8 is provided with the heat shield plate 28, when the second case body 8 is removed, the first space 29 and the second space 30 are not separated from each other in the first case body 7, facilitating maintenance. Easy to replace. 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 from the boundary 32 between the light emitting surface portion 3a and the non-light emitting area toward the center side in the longitudinal direction of the tubular lamp 4 (right side in FIG. 3). Therefore, the heat shield plate 28 has the light emitting surface 3a from the boundary 32 between the light emitting surface 3a and the non-light emitting area.
Located on the side.

Both ends of the tubular lamp 4 in the longitudinal direction are located not behind the non-luminous area but behind the light emitting surface 3a, but the heat shield plate 28 is inclined obliquely, so that the longitudinal direction of the tubular lamp 4 is increased. The vicinity of both ends is located in the second space 30. The tubular lamp 4 has a second range of about 8 mm from the end in the longitudinal direction.
It is located in the 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 ineffective light emitting portion 17 which is dark from the light emitting surface 3a side. Disappears and the emission quality improves.

In addition, the first space 29 of the metal heat shield plate 28
Since the surface facing to is white-painted to form the light reflecting portion 33, brightness is ensured in the area where the heat shield plate 28 is provided, and even if the heat shield plate 28 is provided, the light emitting surface portion 3a is not covered. Can be widely secured. The heat shield plate 28 may be made of resin, and in this case, by using white resin or white-painted resin, a heat shield plate having a reflecting portion can be obtained.

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. When the inclination angle α is 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 uniformity of the light is secured. Further, the heat shield plate 28 is bent at the midway portion 34 in the downward extending direction so that the angle with respect to the thickness direction of the case becomes small, and the tubular lamp 4 is prevented from interfering with the lamp mounting portion 21 and the like. The range located in the two spaces 30 is made small.

The lower end 36 which is the leading end of the heat shield plate 28 in the extending direction.
The tubular lamp 4 to avoid interference with the tubular lamp 4.
A cutout portion 36a is formed in a portion corresponding to, so that the tubular lamp 4 is prevented from being damaged by the heat shield plate 28. Further, a 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 prevents the tubular reflector plate 13 from being damaged by the heat shield plate 28. As a result, the deterioration of the light emission quality due to the damage of the reflection plate 13 is prevented.

A gap 37 is provided between the lower end 36 and the reflection plate 13 (the bottom surface 7a of the first case body) to form the first space 29.
The air flow between the second space 30 and the second space 30 is ensured.
The gap 37 between the lower end 36 and the reflection plate 13 is preferably 10 mm or less in order to avoid a temperature increase in the first space 29 due to a large amount of hot air flowing into the first space 29.
Specifically, it is set to 1.5 mm. Also, the second space 3
In order to promote the replacement of 0 air, the air communication portion 7c
If a large or large number of through holes are formed, the case 2
Although foreign matter easily enters the inside, the foreign matter can be prevented from entering the first space 29 by reducing the gap 37.

According to the present embodiment, the tubular lamp electrode portion 16 which generates heat and the inverter 5 are surrounded by the first case body 7, the second case body 8 and the heat shield 33, and the second space 3 is formed.
Since the heat is shielded from the effective light emitting portion 18 of the tubular lamp 4 in the first space 29, the effective light emitting portion 18
Is less likely to decrease in brightness. Moreover, the first case body 7
Since the air communication between the second space 29 and the outside of the case is ensured by the air communication portion 7c, the inside of the second space 30 is efficiently cooled by the exchange of air from the outside of the case, and the inside of the second space 30 is Due to the presence of the heat shield plate 28, the temperature change in is difficult to be transmitted to the first space 29 side. As a result, there is no abrupt temperature change near the effective light emitting portion 18 of the tubular lamp 4, and a change in brightness (wobble) is prevented. In the case of Schaukasten, the change in brightness (fluctuation) hinders accurate interpretation of the X-ray photographic film, but according to the present embodiment, accurate diagnostic information can be obtained due to the stable brightness.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the matters described in the claims. For example, the application example as a backlight is not limited to Schaukasten, and the same configuration can be applied to a backlight for a liquid crystal display device or the like. Further, in the inventions according to some of the claims, only one of the electrode of the tubular lamp and the inverter may be located in the second space. In addition,
When the inverter is not provided in the second space, the inverter may be arranged not only inside the case but also outside the case.

[0041]

EFFECTS OF THE INVENTION According to the present invention, the longitudinal middle portion of the tubular lamp, which is the effective light emitting portion, is separated by the heat shield plate and is located in the first space where the influence of heat generation is small. The temperature rise in the vicinity of the effective light emitting portion is small, and the decrease in brightness of the tubular lamp is prevented.

[Brief description of drawings]

FIG. 1 is a plan view of a backlight (Schaukasten).

FIG. 2 is a side view (view of arrow II in FIG. 1) of the backlight (Shakasten).

FIG. 3 is a partial cross-sectional view (cross-sectional view taken along the line III-III in FIG. 1) of the backlight (Schaucasten).

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 portion and an effective light emitting portion of the cold cathode tube.

FIG. 6 is a schematic configuration diagram of a conventional backlight.

[Explanation of symbols]

1 Schaukasten (backlight) 2 cases 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 electrodes 17 Ineffective light emitting part 18 Effective light emitting part 28 Heat shield 29 First Space 30 Second space 32 boundaries 33 Reflector 36 Lower edge of heat shield 37 Gap

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/13357 G09F 13/04 Z G09F 13/04 F21Y 103: 00 // F21Y 103: 00 F21S 1/00 EF term (reference) 2H091 FA14Z FA31Z FA42Z FB02 FB08 FC14 FD06 FD11 LA04 LA09 LA18 3K014 AA02 DA05 EA01 EA04 LA04 LB03 LB05 5C096 AA16 BA01 BC01 CA12 CA13 CA25 CA32 CB01 CC10 CC17 CC22 CE33 FA02 FA02 FA02 FA33 CE02 FA02

Claims (10)

[Claims] 1. A direct type backlight in which a tubular lamp having electrode portions at both ends in the longitudinal direction is arranged in a case having a non-light emitting region around a light emitting surface portion and an inverter for lighting the tubular lamp is provided. In the case, a heat shield plate that divides a first space mainly behind the light emitting surface portion and a second space mainly behind the non-light emitting area is provided, and the inverter includes the second space. The tubular lamp is housed in a space, wherein the electrode portions at both ends in the longitudinal direction are located in the second space, and the midway portion in the longitudinal direction is located in the first space. Direct-type backlight. 2. The direct type backlight according to claim 1, wherein the case is formed with an air communication portion that communicates from the second space to the outside of the case. 3. A direct type backlight according to claim 1, wherein a light reflecting portion is provided on a surface of the heat shield plate on the side of the first space. 4. The heat shield plate is located closer to the light emitting surface than the boundary between the light emitting surface and the non-light emitting area, and is located in the first space and the second space.
The direct type backlight according to claim 3, wherein the backlight is separated from the space. 5. The direct type backlight according to claim 3, wherein all the ineffective light emitting portions near both ends in the longitudinal direction of the tubular lamp are housed in the second space. 6. The case comprises a first case body provided with a tubular lamp, and a second case body provided with a light emitting surface portion detachably attached to the first case body, wherein the heat shield plate is the second case body. The direct type backlight according to claim 1, wherein the direct type backlight is provided. 7. The heat shield plate extends from the second case body toward the first case, and the first space is provided between a leading 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 that allows air to flow between the second space and the second space is formed. 8. The direct type backlight according to claim 7, wherein the gap is 10 mm or less. 9. A direct type backlight in which tubular lamps having electrode parts at longitudinal ends are arranged in a case having a non-light emitting region around a light emitting surface part, wherein the light emitting surface part is mainly in the case. A heat shield plate for partitioning a first space behind and a second space mainly behind the non-light-emitting region, wherein the tubular lamp has electrode parts at both longitudinal ends in the second space. The direct type backlight, which is positioned and has a midway portion in the longitudinal direction positioned in the first space. 10. A direct type backlight in which a light source is arranged in a case having a non-light emitting area around a light emitting surface portion and an inverter for turning on the light source is provided. A heat shield plate that separates a first space behind the light emitting surface portion and a second space mainly behind the non-light emitting region is provided, and the inverter is housed in the second space. A direct type backlight.