JPH11219612A - Backlight and display device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] When a fluorescent lamp of a backlight is heated by a planar heater, wiring processing of a lead line from heater control means such as a thermistor or a temperature heater provided in association with the planar heater is simplified. And the space for disposing the planar heater is reduced. SOLUTION: A planar heater 4 is provided at a position facing a long fluorescent lamp 3 which irradiates light to a light guide unit 2, and heater control means 11, 1 for controlling the temperature of the planar heater 4.
The printed circuit board 5 on which the printed circuit board 2 is mounted is connected to the planar heater 4 and provided so as to overlap the planar heater 4. Since the heater control means 11 and 12 are mounted on the printed circuit board 5, the wiring process of the lead lines from the heater control means 11 and 12 is simplified. Further, it is not necessary to secure a wiring space for the lead lines from the heater control means 11 and 12 in the thickness direction of the planar heater 4, and the space for disposing the planar heater is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a backlight and a display device.

[0002]

2. Description of the Related Art In a display device such as a liquid crystal display device or a guide light, a backlight including a light guide unit and a fluorescent lamp disposed on an outer peripheral portion of the light guide unit is widely used.

As a characteristic of the fluorescent lamp, in a low-temperature atmosphere, the mercury vapor pressure in the fluorescent lamp is low, and the luminance of the fluorescent lamp is significantly reduced. For this reason, there has been known a fluorescent lamp used for a backlight, which is heated by a heater.

As a heater for heating a fluorescent lamp, a heater directly attached to a tube surface of the fluorescent lamp is effective. However, with the downsizing of the backlight, a sheet-like planar heater disposed to face the outer peripheral surface of the fluorescent lamp has become widespread. In a conventional sheet heater, a thermistor for controlling the heat generation temperature of the sheet heater, a temperature fuse for preventing the thermal runaway of the sheet heater, and the like are attached on the sheet heater. Leader lines are extended.

[0005]

Therefore, in the conventional planar heater, the wiring process of the lead wire from the thermistor or the temperature heater is complicated.

Further, by attaching a thermistor or a thermal fuse on the planar heater, it is necessary to secure a wiring space for a lead wire from the thermistor or the thermal fuse in the thickness direction of the planar heater. For this reason, the space for disposing the planar heater becomes large, which hinders the reduction in thickness and size of the backlight.

Further, when the fluorescent lamp is heated by the planar heater, it is desirable that the planar heater is sufficiently close to the fluorescent lamp. However, the thickness of the light guide plate is larger than the thickness of the fluorescent lamp. In some cases, the planar heater cannot be brought close enough to the fluorescent lamp.

In the present invention, therefore, it is easy to wire a lead line from a heater control means such as a thermistor or a temperature heater provided in association with a planar heater for heating a fluorescent lamp, and furthermore, including the heater control means. It is an object of the present invention to provide a backlight and a display device capable of reducing a space for disposing a planar heater.

Another object of the present invention is to provide a backlight and a display device in which the planar heater is sufficiently close to the fluorescent lamp so that the fluorescent lamp can be efficiently heated by the planar heater.

[0010]

A backlight according to the present invention comprises: a light guide unit; an elongated fluorescent lamp disposed at a position where light is incident on the light guide unit; A planar heater disposed at a position facing the outer peripheral surface of the fluorescent lamp along the longitudinal direction of the lamp; and a heater control means for the planar heater mounted thereon and disposed to overlap the planar heater. And a printed circuit board connected to the sheet heater. Therefore, since the heater control means is mounted on the printed circuit board, the process of wiring the leads from the heater control means is simplified. Further, it is not necessary to secure a wiring space for the lead wire from the heater control means in the thickness direction of the planar heater, and the space for disposing the planar heater is reduced. As the light guide unit, there are a light guide plate type using a light guide plate and a hollow type in which a reflection unit and a non-isolated diffusion unit are opposed to each other without using a light guide plate.

[0011] The backlight according to claim 2 is a light guide unit; an elongated fluorescent lamp disposed at a position where light is incident on the light guide unit; And a sheet heater on which a heater control means is mounted. Therefore, since the heater control means is mounted on the planar heater, the process of wiring the leads from the heater control means is simplified. Further, it is not necessary to secure a wiring space for the lead wire from the heater control means in the thickness direction of the planar heater, and the space for disposing the planar heater is reduced.

According to a third aspect of the present invention, in the backlight according to the first or second aspect, a casing surrounding at least the planar heater; and a housing formed in the casing and recessed in a shape for housing the heater control means. And a concave portion. Accordingly, the backlight can be made thinner by housing the heater control means in the housing recess formed in the casing.

The invention described in claim 4 is the first to third aspects of the present invention.
In the backlight according to any one of the above, a thermal fuse is mounted as heater control means, and a heater resistance value of a portion of the planar heater facing the thermal fuse is set to be larger than other portions. Therefore, the amount of heat generated in the portion of the planar heater facing the thermal fuse is larger than in the other portions, and the thermal runaway of the planar heater by the thermal fuse is reliably prevented.

[0014] The invention according to claim 5 provides the invention according to claims 1 to 4.
In the backlight according to any one of the above aspects, the heater section of the planar heater and the heater control means are soldered via a joint. Therefore, even when the heater portion of the sheet heater is formed of a material such as stainless steel which is difficult to solder, the soldering between the heater portion and the heater control means can be performed by using a brass or the like which is easy to solder. Is performed well.

The backlight according to the invention of claim 6 is: a light guide unit; an elongated fluorescent lamp disposed at a position where light is incident on the light guide unit; A sheet heater disposed at a position facing the outer peripheral surface of the fluorescent lamp along the surface thereof and having a bent portion bent in a direction approaching the outer peripheral surface of the fluorescent lamp. Therefore, the planar heater approaches the fluorescent lamp, and the fluorescent lamp is satisfactorily heated by the planar heater, so that the luminance rising characteristics of the fluorescent lamp in a low-temperature atmosphere are improved.

According to a seventh aspect of the present invention, in the backlight of the sixth aspect, the fluorescent lamp has a bent portion bent at a substantially right angle, and a cut is made in a portion of the planar heater facing the bent portion. A part is formed. Therefore, by forming a cut portion in a portion of the planar heater that faces the bent portion of the fluorescent lamp, the planar heater is shaped like an L-shape or a U-shape according to the shape of the fluorescent lamp because the fluorescent lamp has an L-shape or a U-shape. Even in the case of forming a U-shape, the planar heater can be easily bent in a direction facing the fluorescent lamp at a portion facing the bent portion of the fluorescent lamp. Further, when the positioning protrusion for positioning the light guide unit is disposed at a position facing the corner of the light guide unit, the cut portion is formed to avoid interference between the planar heater and the positioning protrusion. .

The invention according to claim 8 is the first or second invention.
The backlight according to claim 1, further comprising: a holder formed of a material having insulating properties, heat resistance, and elasticity and housing the heater control unit; and a casing surrounding the planar heater, wherein the casing includes the planar shape. A holder accommodating recess for accommodating the heater in a state of being pressed against the heater is provided. Therefore, heater control means such as a thermistor and a temperature fuse are housed in the holder housing recess in a state where the holder for housing them is pressed against the planar heater. in this case,
The holder is not limited to the configuration in which the holder is directly pressed into contact with the sheet heater, but includes a configuration in which a thin substrate is interposed between the two.

According to a ninth aspect of the present invention, in the backlight according to the eighth aspect, a part of one surface of the holder opposite to the planar heater is elastically bent by contacting the inner surface of the holder storage recess. A flexible projection is formed. Therefore, the holder is pressed against the planar heater by a reaction force when the protrusion is pressed against one surface of the holder storage recess and elastically deformed.

According to a tenth aspect of the present invention, in the backlight according to the eighth aspect, a part of the one surface of the holder storage concave portion facing the planar heater is elastically bent by pressing one surface of the holder. A protrusion is formed. Therefore, the holder is pressed against the sheet heater by a reaction force when the holder is pressed by the protrusion formed in the holder storage recess and elastically deformed.

According to an eleventh aspect of the present invention, in the backlight according to the first aspect, a flexible board is used as a printed board, and a wire harness connected to the outside is connected to the flexible board. Accordingly, when an external force acts on the wire harness, the bending of the flexible substrate is allowed, so that the external force applied to the connection between the flexible substrate and the wire harness is limited.

According to a twelfth aspect of the present invention, in the flexible backlight according to the eleventh aspect, the flexible substrate fixedly includes a reinforcing plate on a back surface of a portion to which the wire harness is connected, and includes a planar heater. The surrounding casing includes a stopper for restricting the movement of the reinforcing plate against an external force in a direction in which the wire harness is pulled. Therefore, when the wire harness is pulled for some reason, the tensile force acts on the contact portion between the reinforcing plate and the stopper portion of the casing.

According to a thirteenth aspect of the present invention, there is provided a display device according to any one of the first to twelfth aspects, and a display unit disposed at a position opposed to an emission surface of the light guide unit in the backlight. Is provided. Therefore,
In this display device, the wiring process of the lead wires from the heater control means of the planar heater is simplified, and the space for disposing the planar heater is reduced, so that the display device is made thinner and smaller. Further, since the planar heater is close to the fluorescent lamp, the luminance rising characteristics of the fluorescent lamp in a low-temperature atmosphere are improved, and the display characteristics of the display device are improved.

[0023]

FIG. 1 shows a first embodiment of the present invention.
A description will be given based on FIG. 1 is an exploded perspective view showing a backlight, FIG. 2 is a vertical sectional front view showing a part of a liquid crystal display device using the backlight, and FIG. 3 is a bottom view showing a planar heater and a printed circuit board.

First, the backlight 1 will be described.
As shown in FIG. 1, the backlight 1 includes a light guide unit 2, an L-shaped fluorescent lamp 3 disposed at a position where light enters the light guide unit 2, and a surface for heating the fluorescent lamp 3. It comprises a heater 4, a printed circuit board 5, and casings 6, 7 for accommodating the light guide unit 2, the fluorescent lamp 3, the planar heater 4 and the printed circuit board 5.

The light guide unit 2 is formed in a flat rectangular shape, and the light guide plate 8 is formed as a light emitting surface 8a which emits light having one flat surface incident thereon, and a light emitting surface 8a of the light guide plate 8 on the light emitting surface 8a. And a reflection sheet 10 laminated on the other flat surface side of the light guide plate 8.

As shown in FIG. 1 and FIG.
Is a stainless steel heater section 4a and a PET film 4b.
The fluorescent lamp 3 is disposed almost directly below the fluorescent lamp 3 with the reflection sheet 10 interposed therebetween, and is formed in an L-shape extending along the longitudinal direction of the fluorescent lamp 3.

On the printed circuit board 5, wiring is printed, and a thermistor 11 as heater control means and a thermal fuse 12 as heater control means are mounted. The printed circuit board 5 is disposed so as to overlap with the planar heater 4, and the heater section 4a of the planar heater 4 and the wiring on the printed circuit board 5 are arranged so that the heater section 4a and the thermal fuse 12 are connected in series. Soldered. A lead 13 of the thermistor 11 and a lead 14 of the heater section 4a and the thermal fuse 12 are led out from the edge of the printed circuit board 5, and these leads 13 and 14 are
And do not overlap.

A brass stop 15 is attached to a soldering portion of the heater portion 4a of the sheet heater 4. Further, in the portion of the planar heater 4 facing the thermal fuse 12, the heater resistance value is increased by making the heater portion 4a thinner than in other portions, and the amount of heat generated in the portion of the heater portion 4a facing the thermal fuse 12 is reduced. More than the other parts.

A stepped recess 16 is formed on the inner peripheral surface of the casing 7 at a portion facing the printed board 5, and the printed board 5 is accommodated in the stepped recess 16. Further, a housing recess 17 is formed in the stepped recess 16 at a position facing the thermistor 11 and the thermal fuse 12, and the thermistor 11 and the thermal fuse 12 are housed in these housing recesses 17.

Next, the liquid crystal display device 18 as a display device
Will be described. The liquid crystal display device 18 includes the backlight 1 and a transmissive liquid crystal display element 19 (see FIG. 2) which is a display unit disposed on the light diffusion sheet 9.

In such a configuration, since the sheet heater 4 is disposed almost directly below the fluorescent lamp 3 and is disposed along the longitudinal direction of the fluorescent lamp 3, when the liquid crystal display device 18 is started up. The fluorescent lamp 3 is heated by the planar heater 4, and the luminance rising characteristics of the fluorescent lamp 3 are improved even in a low-temperature atmosphere.

Here, the lead 13 of the thermistor 11
And the lead wire 14 of the heater section 4a and the thermal fuse 12
Are drawn out from the edge of the printed circuit board 5, so that the wiring process for these lead lines 13 and 14 is simplified. Further, since the lead lines 13 and 14 do not overlap with the planar heater 4, it is not necessary to secure a wiring space for the lead lines 13 and 14 in the thickness direction of the planar heater 4, and the planar heater 4 is placed in a narrow space. The backlight 1 and the liquid crystal display 18 using the backlight 1 can be made thinner and smaller. Furthermore, since the heater section 4a of the sheet heater 4 and the thermal fuse 12 are connected in series, the thermal fuse 1
The two lead wires 14 also serve as the lead wires of the planar heater 4, and the number of lead wires is reduced.

On the inner peripheral surface of the casing 7 surrounding the planar heater 4 and the printed board 5, a stepped recess 16 and a housing recess 17 are provided.
Are formed, the printed board 5 is housed in the step-shaped recess 16, and the thermistor 11 and the thermal fuse 12 are housed in the housing recess 17. For this reason, the planar heater 4
Even when the thermistor 11 and the thermal fuse 12 mounted on the printed circuit board 5 are overlaid on the plane of the printed circuit board 5, the backlight 1
In addition, the thickness of the liquid crystal display device 18 is reduced.

In the portion of the planar heater 4 facing the thermal fuse 12, the heater portion 4a is made thinner so that the heater resistance value is made larger than in other portions. For this reason, when the planar heater 4 is energized, the amount of heat generated in the portion facing the thermal fuse 12 is larger than in the other portions.
Therefore, when the thermistor 11 breaks down or the like,
When the thermal runaway occurs, the surface heater 4 has the highest temperature at the portion facing the thermal fuse 12, so that the thermal fuse 12 is melted early, and the thermal runaway of the planar heater 4 can be prevented. it can.

Since the brass fitting 15 is attached to the soldering portion of the heater portion 4a of the planar heater 4, even if the heater portion 4a is made of stainless steel which is difficult to be soldered, it is difficult to connect the printed board 5 to the heater. Soldering can be performed well.

Note that the lead lines 13 and 14 may be made of a flexible printed circuit board, so that the thickness can be reduced.

Next, a second embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. 1 to 3
The same parts as those described in are denoted by the same reference numerals, and description thereof will be omitted (the same applies hereinafter). 4 is an exploded perspective view showing a backlight, FIG. 5 is a vertical sectional front view showing a part of a liquid crystal display device using the backlight, and FIG. 6 is a plan view showing a planar heater.

First, the backlight 20 will be described. As shown in FIG. 4 and FIG.
A light guide unit 2; a long fluorescent lamp 3 disposed at a position where light enters the light guide unit 2; a planar heater 21 for heating the fluorescent lamp 3; It comprises a lamp 3 and casings 22 and 23 for accommodating a planar heater 21.

As shown in FIG. 4 and FIG.
Reference numeral 1 denotes a stainless steel heater portion 21a formed on a PET film 21b, which is disposed almost directly below the fluorescent lamp 3 with a reflective sheet 10 interposed therebetween, and extends along the longitudinal direction of the fluorescent lamp 3. It is formed in a protruding L-shape. The planar heater 21 includes a thermistor 11 and a thermal fuse 1.
2 are mounted, and the heater 21a and the thermal fuse 12 are soldered in series. From the edge of the planar heater 21, the lead wire 13 of the thermistor 11 and the heater 2
1a and the lead line 14 of the thermal fuse 12 are drawn out, and these lead lines 13 and 14 are connected to the sheet heater 21.
And do not overlap.

The soldering portion between the heater 21a of the sheet heater 21 and the thermal fuse 12 is provided with a brass fitting 15
Is attached. In a portion of the planar heater 21 facing the thermal fuse 12, a heater portion 21a
, The heater resistance value is made larger than that of the other portions, and the amount of heat generated in the portion of the heater portion 21a facing the thermal fuse 12 is larger than that of the other portions.

As shown in FIGS. 4 and 5, the casing 2
3, the thermistor 11 and the thermal fuse 12
The receiving recesses 17 are formed at positions opposite to the above, and the thermistor 11 and the thermal fuse 12 are housed in these receiving recesses 17.

Next, the liquid crystal display device 24 as a display device
Will be described. The liquid crystal display device 24 includes the backlight 20 and a transmissive liquid crystal display element 19 (see FIG. 5) disposed on the light diffusion sheet 9.

In such a configuration, the planar heater 21
Is located almost directly below the fluorescent lamp 3 and is disposed along the longitudinal direction of the fluorescent lamp 3.
When the fluorescent lamp 3 is started, the fluorescent lamp 3 is heated by the planar heater 21, and the luminance rising characteristic of the fluorescent lamp 3 is improved even in a low-temperature atmosphere.

Here, the lead 13 of the thermistor 11
And lead wire 1 of heater section 21a and thermal fuse 12
4 is pulled out from the edge of the planar heater 21,
The wiring process of these lead lines 13 and 14 is simplified. In addition, the lead lines 13 and 14 are formed by the sheet heater 21.
It is not necessary to secure a wiring space for the lead wires 13 and 14 in the thickness direction of the sheet heater 21 because the sheet heater 21 does not overlap with the sheet heater 21, and the sheet heater 21 can be disposed in a narrow space. 20 and this backlight 2
0 can be made thinner and smaller. Further, the heater unit 21 of the planar heater 21
a and the thermal fuse 12 are connected in series,
The lead wire 14 of the thermal fuse 12 also serves as the lead wire of the sheet heater 21, and the number of lead wires is reduced.

A housing recess 17 is formed on the inner peripheral surface of the casing 23 surrounding the planar heater 21 and the printed circuit board 5.
The thermistor 11 and the thermal fuse 12 are housed in the housing recess 17. For this reason, the thermistor 11 and the temperature fuse 12 mounted on the planar heater 21
The thickness of the backlight 20 and the liquid crystal display device 24 can be reduced even when the backlight 20 and the liquid crystal display device 24 protrude from the flat surface of the light emitting device 1.

Thermal fuse 12 in planar heater 21
, The heater resistance value is made larger than the other portions by making the heater portion 21a thinner. For this reason, when the planar heater 21 is energized, the amount of heat generated in the portion facing the thermal fuse 12 is larger than in the other portions. Therefore, when the planar heater 21 is about to run out of heat due to a failure of the thermistor 11, the temperature of the planar heater 21 is highest at a portion facing the thermal fuse 12, and the thermal fuse 12 is melted at an early stage. Thermal runaway of the heater 4 can be prevented.

Since the brass ferrule 15 is attached to the soldering portion of the heater portion 21a of the planar heater 4, even if the heater portion 21a is made of stainless steel which is difficult to solder, the connection with the printed board 5 can be made. Soldering can be performed well.

Next, a third embodiment of the present invention will be described with reference to FIG.
A description will be given based on FIG. FIG. 7 is a vertical sectional front view showing a part of the liquid crystal display device, and FIG. 8 is a perspective view showing a planar heater.

First, the liquid crystal display device 25 as a display device will be described. The liquid crystal display device 25 includes a backlight 26 and a transmissive liquid crystal display element 19.

The backlight 26 includes the light guide unit 2 and
A U-shaped fluorescent lamp 27 disposed at a position where light enters the light guide unit 2, a planar heater 28 for heating the fluorescent lamp 27, these light guide unit 2, the fluorescent lamp 27, A casing 29 for housing the heater 28,
30.

As shown in FIG. 8, the planar heater 28 has a heater portion 28a made of stainless steel formed on a PET film 28b, and has a U-shape extending along the longitudinal direction of the fluorescent lamp 27. Is formed.

The planar heater 28 includes the planar heater 28.
Is located at a position where light emitted from the fluorescent lamp 27 is not prevented from being incident on the light guide unit 2.
Folded portion 31 bent in a direction close to the outer peripheral surface of 7
Having. Further, a cut portion 32 is formed in the planar heater 28 at a portion opposed to a bent portion where the fluorescent lamp 27 is bent at a substantially right angle.

In such a configuration, the planar heater 28
Is bent at the bent portion 31 to bring the planar heater 28 close to the fluorescent lamp 27, so that the heating performance of the fluorescent lamp 27 by the planar heater 28 is improved, and the luminance rising characteristics of the fluorescent lamp 27 in a low-temperature atmosphere. Is greatly improved.

Further, since the notch 32 is formed in a portion of the planar heater 28 facing the bent portion of the fluorescent lamp 27, the planar heater 28 can be formed because the fluorescent lamp 27 is U-shaped or L-shaped. Even when the sheet heater 28 is formed in a U-shape or an L-shape following the shape, the planar heater 28 is not bent.
It can be easily bent from one. Further, when a positioning projection (not shown) for positioning the light guide unit 2 is formed at a position facing a corner of the light guide unit 2 in the casing 30, the notch 32 is formed to form the planar heater. Interference between the positioning projection and the positioning projection is avoided.

Next, a fourth embodiment of the present invention will be described with reference to FIG.
A description will be given based on FIG. FIG. 9 is a perspective view showing a state in which a planar substrate and a flexible substrate are stacked, and FIG.
(A) is a perspective view of a holder accommodating the heater control means, (b) is a sectional view of a holder accommodating recess formed in a casing, and (c) is a cross section showing a state in which the holder is accommodated in the holder accommodating recess. FIG.

The configuration of the backlight according to the present embodiment and the following embodiments is basically the same as the configuration of the backlights 1, 20, 26 in the previous embodiment. This embodiment is characterized by a support structure of the heater control element.

That is, as shown in FIG. 9, the same planar heater 4 as in the first embodiment is used, but a flexible substrate 33 is used as a printed circuit board. The flexible board 33 has a wiring pattern 33a printed thereon and a thermistor 34 and a thermal fuse 35 as heater control means mounted thereon. The flexible substrate 33 is disposed so as to overlap the planar heater 4, and the heater portion 4a of the planar heater 4 and the wiring pattern 33a on the flexible substrate 33 are arranged in series with the heater portion 4a and the thermal fuse 35. Connected. The thermistor 34 and the thermal fuse 35
Are stored in the holders 36 and 37 without play. These holders 36 and 37 are formed of a material such as rubber having insulation, heat resistance and elasticity, and are formed in a rectangular parallelepiped shape so that one surface thereof is in close contact with the flexible substrate 33.

A protruding piece 38 is formed at the center of the flexible board 33 so as to protrude outward. At this protruding piece 38, a wire harness 39 is soldered to a wiring pattern 33 a on the flexible board 33. I have.
A connector 40 for connecting a series circuit of the heater section 4 a and the thermal fuse 35 and both ends of the thermistor 34 to an external circuit (not shown) is provided at an end of the wire harness 39.
Is connected. Note that the wire harness 39 does not overlap with the planar heater 4.

As shown in FIG. 10A, the holder 36,
Two projections 41 that can be elastically bent are formed on a part of one surface on the opposite side of the sheet heater 37. Then, as shown in FIG. 10 (b), the casing 6 (see FIG. 1) has a holder storage recess 4 for storing the holders 36 and 37.
2 are formed. Depth t of this holder storage recess 42
2 is set to a value smaller than the height t1 of the holders 36 and 37 including the protrusion 41. Therefore, FIG.
As shown in FIG.
When the casing 6 and the casing 7 are connected to each other, the holders 36 and 37, the flexible substrate 33, and the sheet heater 4 are sandwiched between the casings 6 and 7, and the holders 36 and 37 have protrusions 41 in the holder storage recesses 42. Are pressed against the sheet heater 4 by a reaction force when the sheet is pressed against the inner surface and elastically deformed. In this example, the holders 36 and 37 are pressed into contact with the sheet heater 4 via the flexible substrate 33. As shown in FIG. 4, the heater 21a, the thermistor 11, the temperature fuse 12 and the external circuit are placed on the PET film 21b. When the ferrules 15 connected to the
6, 37 can be directly pressed against the planar heater 21;
Such a configuration may be adopted.

In such a configuration, as shown in FIG. 10C, the thermistor 34 and the temperature fuse 35 are held in the holder storage recesses in a state where the holders 36 and 37 for storing these are pressed against the sheet heater 4 side. 42
The temperature of the planar heater 4 can be accurately detected by the thermistor 34. As means for pressing the holders 36 and 37 against the sheet heater 4 side, the holders 36 and 37 are used.
A part of one surface opposite to the surface heater 4 is provided with a protrusion 41 which is elastically bent by contacting the inner surface of the holder accommodating recess 42.
Is formed, the height t1 of the holders 36 and 37 and the depth t2 of the holder accommodating recess 42 do not need to be formed with strict dimensions, and the manufacture is easy.

This is not limited to the number of protrusions 41 formed on one surface of the holders 36, 37, but
The same applies to the case where three or more projections 41 are formed or one projection 41 is formed as shown in FIG.

Next, a fifth embodiment of the present invention will be described with reference to FIG.
2 will be described. FIG. 12A is a side view of a holder for storing the heater control means, FIG. 12B is a cross-sectional view of a holder storage recess formed in the casing, and FIG. 12C is a state in which the holder is stored in the holder storage recess. FIG.

As shown in FIG. 12A, the holder 36,
37 has a flat rectangular parallelepiped shape on each surface.
As shown in (b), a protrusion 43 is formed on the inner surface of the holder storage recess 42 formed in the casing 6 (see FIG. 1). The depth t2 at the apex of the protrusion 43 of the holder storage recess 42 is set to a value smaller than the height t1 of the holders 36 and 37. Therefore, as shown in FIG. 12 (c), the holders 36, 37 are housed in the holder housing recess 42, and when the casing 6 and the casing 7 are connected, the holders 36, 37, the flexible board 33 and The holders 36 and 37 are pressed against the sheet heater 4 by a reaction force generated when the holders 36 and 37 are elastically deformed by being pressed by the protrusions 43 of the holder accommodating recess 42. The effect of this is the same as in the case of the fifth embodiment.

Also in this example, as a means for pressing the holders 36 and 37 against the planar heater 4, a part of one surface of the holder accommodating recess 42 facing the planar heater 4 is provided on one surface of the holders 36 and 37. Is formed, the protrusions 43 are formed to press and resiliently bend, so that the height t1 of the holders 36 and 37 and
It is not necessary to form the depth t2 of the holder accommodating recess 42 with a strict size, and the manufacture is easy.

This is not limited to the number of the protrusions 43 formed on one surface of the holder accommodating recess 42, and three or more protrusions 43 may be formed or one protrusion 43 may be formed.
The same applies to the case where is formed.

Next, a sixth embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIGS. FIG. 13 is a perspective view showing a state in which a planar substrate and a flexible substrate are stacked, and FIG.
4 is a cross-sectional view showing a connection structure between the sheet heater and the flexible board, FIG. 15 is an exploded perspective view showing a support structure of the flexible board to which the wire harness is connected, and FIG. 16 is a support of the flexible board to which the wire harness is connected. FIG. 17 is a front view showing the structure, and FIG. 17 is a cross-sectional view showing a support structure for a flexible substrate to which a wire harness is connected.

As shown in FIG. 13, in the present embodiment,
Although the same planar heater 4 as that of the first embodiment is used, a flexible substrate 33 is used as a printed circuit board, as in the fourth embodiment (FIG. 9). In this case, the heater portion 4a of the planar heater 4 and the flexible substrate 3
The third wiring pattern 33a is connected by a stopper 15 as shown in FIG. That is, the diaper 15 penetrates through the sheet heater 4 and the flexible substrate 33 and mechanically couples the two together, and one end is crimped to one end of the heater portion 4a or a wiring pattern continuous with the heater portion 4a. Is the wiring pattern 33a of the flexible substrate 33
Is crimped. Such a connection structure is the same in the fourth embodiment (FIG. 9).

Here, the features of this embodiment will be described. In the present embodiment, a reinforcing plate 44 is fixed to the surface of the flexible board 33 opposite to the wiring pattern of the protruding piece 38. Then, as shown in FIG.
When the flexible substrate 33 is bent near the base of the protrusion 38 in the casing 6 (see FIG. 1), the protrusion 38
Is formed in a vertical state, and stopper portions 46 that contact both ends of the reinforcing plate 44 are formed on both sides of an end portion of the guide concave portion 45. In FIG. 15, 47 is a projecting piece 38, a wire harness 39, and a reinforcing plate 44.
And a fixing tape for binding the peripheral wall of the guide recess 45.

Therefore, as shown in FIGS. 16 and 17,
The sheet heater 4 and the flexible substrate 33 are connected to the casing 6.
And the casing 7. Then, the projecting piece 38 of the flexible substrate 33 is bent upward to guide the concave portion 45.
Is pushed in, both ends of the reinforcing plate 44 abut against the lower surface of the stopper 46. In this case, the position of the reinforcing plate 44 and the position of the stopper 46 are determined so that a curved margin can be obtained at the base of the protruding piece 38 when they come into contact with each other.
In this state, the projecting piece 38, the wire harness 39, and the reinforcing plate 4
4 and the peripheral wall of the guide recess 45 are bound by a fixing tape 47.

In such a configuration, the flexible substrate 3
When an external force acts on the wire harness 39 until the wire 3 is fixed to the guide recess 45 of the casing 6, the flexible board 33 is allowed to bend, so that it is applied to the connection between the flexible board 33 and the wire harness 39. External force can be limited.

The flexible board 33 is provided with a reinforcing plate 44 fixedly on the back surface of the portion to which the wire harness 39 is connected.
Since the stopper portion 46 for restricting the movement of the reinforcing plate 44 against the external force in the direction in which the wire harness 39 is pulled is provided, the wire harness 39 is fixed for some reason with the flexible substrate 33 fixed to the guide recess 45. Is pulled, the tensile force acts on the contact portion between the reinforcing plate 44 and the stopper portion 46 of the casing 6, so that an excessive force acts on the connection portion between the flexible board 33 and the wire harness 39. And a good connection state can be maintained for a long time.

It is to be noted that there is a conventional example in which a planar heater 4 is used as a heater for heating a fluorescent lamp, and a printed circuit board is arranged to face the planar heater for wiring. Specifically, as shown in FIG. 18, the sheet heater 100 and the printed board 101 are bonded with an adhesive 102, and the heater section 100 a of the sheet heater 100 is connected to the wiring pattern 101 a of the printed board 101. Next, holes for passing the conductive pins 103 are formed in both of them. In this case, the heater unit 1
The hole formed in the insulating layer 100b such as a PET film laminated on both sides of the heater unit 100a is made larger than the hole formed in the heater unit 100a. The pins 103 are inserted into the holes of the board 101 and the solder 105 is filled from above the wiring pattern 101 a of the printed board 101 into the periphery of the pins 103 and the inside of the fitting 104.

Such a structure is used for connecting the pins 10
3 requires more complicated soldering work, which increases the number of working steps and lowers the yield.

However, according to the structure of the present embodiment, as shown in FIG.
3 and the electrical connection between the heater portion 4a of the planar heater 4 and the wiring pattern 33a of the flexible substrate 33 can be performed only by tightening the diaper 15. Therefore, the number of parts and the number of work steps can be reduced.

[0075]

According to the backlight of the first aspect of the present invention, since the heater control means is mounted on the printed circuit board which is disposed so as to overlap with the planar heater, the wiring of the lead line from the heater control means is provided. Processing can be simplified, and furthermore, it is not necessary to secure a wiring space for a lead line from the heater control means in the thickness direction of the planar heater, so that a space for disposing the planar heater can be reduced. ,
Thus, the backlight can be made thinner and smaller.

According to the backlight according to the second aspect of the present invention, since the heater control means is mounted on the planar heater, it is possible to simplify the wiring process of the lead-out line from the heater control means. Since it is not necessary to secure a wiring space for the lead wire from the heater control means in the thickness direction of the planar heater, it is possible to reduce the space for disposing the planar heater, thereby reducing the thickness and size of the backlight. Can be achieved.

According to the backlight of the third aspect of the present invention, the heater control means is housed in the housing recess formed in the casing, so that the backlight can be further thinned.

According to the backlight of the fourth aspect of the invention, the heat generated in the portion of the planar heater facing the thermal fuse becomes larger than in the other portions, and the thermal fuse is turned off when the planar heater is about to run out of heat. By melting the sheet heater quickly, thermal runaway of the sheet heater can be reliably prevented.

According to the backlight of the fifth aspect of the present invention, even when the heater portion of the sheet heater is formed of a material such as stainless steel which is difficult to be soldered, a brass or the like which can be easily soldered is used. By using this, the soldering between the heater section and the heater control means can be performed favorably.

According to the backlight of the sixth aspect of the invention, the luminance rising characteristics of the fluorescent lamp in a low-temperature atmosphere can be further improved by bending the planar heater at the bent portion so as to approach the fluorescent lamp. it can.

According to the backlight of the present invention, in the planar heater having a bent portion, a cut portion is formed in a portion of the planar heater facing the bent portion of the fluorescent lamp. Therefore, even when the planar heater is formed in an L-shape or a U-shape according to the shape because the fluorescent lamp is an L-shape or a U-shape, the planar heater is formed in a portion opposed to the bent portion of the fluorescent lamp. Can be easily bent in a direction close to the fluorescent lamp. Furthermore, when the positioning protrusion for positioning the light guide unit is disposed at a position facing the corner of the light guide unit, by forming a cut portion, it is possible to avoid interference between the planar heater and the positioning protrusion. The arrangement of the planar heater can be performed well.

According to the backlight of the present invention, the heater control means such as a thermistor and a temperature fuse is provided.
It can be housed in a holder formed of a material having insulation, heat resistance and elasticity, and can be housed in a holder housing recess of the casing in a state where the holder is pressed against the sheet heater. Thereby, the sensitivity of the heater control means to the heat of the planar heater can be increased, and the thermal runaway of the planar heater can be more effectively prevented.

According to the backlight of the ninth aspect, a part of one surface of the holder opposite to the planar heater includes:
Since the protrusion that can elastically bend in contact with the inner surface of the holder storage recess is formed, the protrusion of the holder can be replaced with the holder storage recess without strictly controlling the dimensions of the holder and the holder storage recess. The holder can be pressed against the planar heater by a reaction force when the projection is elastically deformed by pressing on one surface.

The backlight according to the invention of claim 10 is:
A part of one surface of the holder recess that faces the planar heater is formed with a protrusion that presses one surface of the holder and elastically bends, so the dimensions of the holder and the holder recess are strictly controlled. Even without doing so, the holder can be pressed by the protrusion of the holder storage recess, and the holder can be pressed against the planar heater by the reaction force when the holder is elastically deformed.

According to the backlight of the present invention, a flexible board is used as a printed board, and a wire harness connected to the outside is connected to the flexible board, so that an external force acts on the wire harness. In this case, since the bending of the flexible substrate is allowed, the external force applied to the connection between the flexible substrate and the wire harness can be limited. Thus, according to the backlight of the twelfth aspect, the flexible substrate fixedly includes the reinforcing plate on the back surface of the portion to which the wire harness is connected, and the casing surrounding the planar heater includes the wire harness. A stopper portion for restricting the movement of the reinforcing plate against an external force in the direction in which the wire harness is pulled, so that if the wire harness is pulled for any reason, the pulling force is applied to the stopper portion between the reinforcing plate and the casing. Can be received at the contact part. Thereby, disconnection of the wire harness can be more effectively prevented.

According to the display device of the thirteenth aspect of the present invention, it is possible to simplify the wiring process of the lead wires from the heater control means of the planar heater, and to reduce the space for disposing the planar heater. The device can be made thinner and smaller. Further, since the planar heater is close to the fluorescent lamp, the luminance rising characteristics of the fluorescent lamp in a low-temperature atmosphere are improved, and the display characteristics of the display device can be improved.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a backlight according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional front view showing a part of a liquid crystal display device using the backlight.

FIG. 3 is a bottom view showing a state where the planar heater and the printed circuit board are overlaid;

FIG. 4 is an exploded perspective view showing a backlight according to a second embodiment of the present invention.

FIG. 5 is a longitudinal sectional front view showing a part of a liquid crystal display device using the backlight.

FIG. 6 is a plan view showing a planar heater.

FIG. 7 is a vertical sectional front view showing a part of a liquid crystal display device according to a third embodiment of the present invention.

FIG. 8 is a perspective view showing a planar heater.

FIG. 9 is a perspective view showing a state in which a planar substrate and a flexible substrate according to a fourth embodiment of the present invention are overlaid.

10A is a perspective view of a holder for storing the heater control means, FIG. 10B is a cross-sectional view of a holder storage recess formed in the casing, and FIG. 10C is a cross-section showing a state where the holder is stored in the holder storage recess. Figure

FIG. 11 is a perspective view showing a modification of the holder.

FIG. 12 (a) is a side view of a holder accommodating a heater control unit according to a fifth embodiment of the present invention, FIG. 12 (b) is a sectional view of a holder accommodating recess formed in a casing, and FIG. )
Is a sectional view showing a state in which the holder is stored in the holder storage recess.

FIG. 13 is a perspective view showing a state in which a planar substrate and a flexible substrate are stacked.

FIG. 14 is a sectional view showing a connection structure between a planar heater and a flexible substrate.

FIG. 15 is an exploded perspective view showing a support structure of a flexible board to which a wire harness is connected.

FIG. 16 is a front view showing a support structure of a flexible board to which a wire harness is connected.

FIG. 17 is a sectional view showing a support structure of a flexible board to which a wire harness is connected.

FIG. 18 is a cross-sectional view showing a conventional connection structure between a planar heater and a printed board.

[Explanation of symbols]

 1, 20, 26: backlight 2: light guide unit 3, 27: fluorescent lamp 4, 21, 28: planar heater 4a, 21a: heater unit 5: printed circuit board 7, 23: casing 11: heater control means 12: Heater control means, thermal fuse 15: Stop 17: Housing recess 18, 25: Display device 19: Display section 31: Bend section 32: Cut section 33: Printed circuit board, flexible board 34, 35: Heater control section 36, 37: Holder 39: Wire harness 41, 43: Projection 42: Holder recess 44: Reinforcement plate 46: Stopper

Continuation of the front page (72) Inventor Jun Yajima 4-3-1 Higashishinagawa, Shinagawa-ku, Tokyo Toshiba Lighting & Technology Corporation

Claims (13)

[Claims] A light guide unit; an elongated fluorescent lamp disposed at a position where light is incident on the light guide unit; and an outer peripheral surface of the fluorescent lamp along a longitudinal direction of the fluorescent lamp. A sheet heater disposed at an opposing position; and a printed circuit board on which heater control means for the sheet heater is mounted, which is disposed so as to overlap with the sheet heater and connected to the sheet heater. Backlight provided. 2. A light guide unit; an elongated fluorescent lamp disposed at a position where light is incident on the light guide unit; and an outer peripheral surface of the fluorescent lamp along a longitudinal direction of the fluorescent lamp. A planar heater provided at a position opposite to the heater and having a heater control means mounted thereon. 3. A housing comprising: a casing surrounding at least a planar heater; and a housing recess formed in the casing and recessed in a shape for housing the heater control means.
Or the backlight according to 2. 4. A heater according to claim 1, wherein a thermal fuse is mounted as the heater control means, and a heater resistance value of a portion of the planar heater facing the thermal fuse is set to be larger than other portions. Backlight. 5. The backlight according to claim 1, wherein the heater section of the planar heater and the heater control means are soldered via a staple. 6. A light guide unit; an elongated fluorescent lamp disposed at a position where light is incident on the light guide unit; and an outer peripheral surface of the fluorescent lamp along a longitudinal direction of the fluorescent lamp. And a planar heater having a bent portion which is disposed at an opposing position and is bent in a direction approaching an outer peripheral surface of the fluorescent lamp. 7. The backlight according to claim 6, wherein the fluorescent lamp has a bent portion bent at a substantially right angle, and a cut portion is formed in a portion of the planar heater facing the bent portion. 8. A holder formed of a material having insulating properties, heat resistance and elasticity and containing heater control means,
3. The backlight according to claim 1, further comprising: a casing surrounding the planar heater, wherein the casing includes a holder storage recess configured to store the holder in a state of being pressed against the planar heater. 4. 9. The holder according to claim 8, wherein a part of one surface of the holder opposite to the planar heater is formed with a projection which can be elastically bent by contacting the inner surface of the holder storage recess. Backlight. 10. The backlight according to claim 8, wherein a projection is formed on a part of the one surface of the holder storage recess facing the planar heater, the protrusion protruding one surface of the holder to elastically bend. 11. The backlight according to claim 1, wherein a flexible board is used as the printed board, and a wire harness connected to the outside is connected to the flexible board. 12. A flexible board fixedly provided with a reinforcing plate on a back surface of a portion to which a wire harness is connected, and a casing surrounding a sheet heater is provided with a casing against the external force in a direction of pulling the wire harness. 12. The backlight according to claim 11, further comprising a stopper for restricting the movement of the reinforcing plate. 13. A display device comprising: the backlight according to any one of claims 1 to 12; and a display unit disposed at a position facing an emission surface of the light guide unit in the backlight. .