JPH08122533A - Surface light source device - Google Patents

Abstract

PURPOSE: To reduce the power consumption, to raise the luminance, and to reduce the dead space by arranging a single-tube fluorescent lamp around a light guide means and leading out the lamp electrode of one end and that of the other in the same direction. CONSTITUTION: A U-Shaped Single-tube lamp is used as a fluorescent lamp 1 and is arranged around three sides of a plane quadrangular light guide body 2. Lamp electrodes 1a and 1b in one end and the other of this fluorescent lamp 1 are led out in the same direction. Consequently, the quantity of light of the luminous flux made incident on the light guide body 2 is increased by the increase of length of the lamp in comparison with a straight double-tube lamp or an L-shaped tube lamp in the edge light system, and the luminance of light emission is raised. Since lamp electrodes 1a and 1b are led out in the same direction, the dead space is reduced. Preferably, first and third sides of the U-shaped fluorescent lamp 1 arranged around three sides of the light guide body 2 are made free, and the lamp 1 is fixed by the second side. Thus, a trouble like a break of the fluorescent lamp 1 is prevented even if this device is used in a place of much oscillation like a vehicle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface light source device used as a backlight for liquid crystal display devices and the like.

[0002]

2. Description of the Related Art Conventionally, as a backlight used for a liquid crystal display element, there are a direct type in which a fluorescent lamp is arranged directly below the liquid crystal display element and an edge light (or light guide) type. Both have their own characteristics, but the edge light method is superior in terms of thinning the liquid crystal display device.

In this edge light system, as shown in FIG. 9, light from a fluorescent lamp 1 is introduced directly or by a lamp reflector 5 from an end surface of a light guide 2 made of a resin such as acrylic. . The light introduced is the light guide 2.
Although the light is totally reflected in the light guide 2 and progresses, the refractive index changes due to the reflection film 4 formed on the back surface of the light guide 2.
Part of the light is transmitted from the front of the. This transmitted light is diffused by the diffusion film 3 and emitted as uniform light from the flat surface portion. The reflective film 4 may be formed on the entire back surface of the light guide 2, or may be formed in dot units in order to eliminate uneven brightness. In addition, the lens film is placed on the diffusion film 3 so that the light flux falls within a predetermined range (for example,
It is also possible to condense light up and down, left and right in a range of 45 ° to increase the brightness.

In such an edge light system,
The emission brightness is lower than that of the direct method. Therefore, as shown in FIG. 10, a straight-tube two-lamp system in which fluorescent lamps 11 and 12 are arranged on two sides of the light guide 2 or one L-shaped fluorescent lamp 13 as shown in FIG. 11 is guided. L placed on two sides of body 2
As a character tube system, the emission brightness is increased. In addition, reference numeral 8 in the drawing denotes a display area of the liquid crystal display element arranged on the light guide 2.

[0005]

[Problems to be Solved by the Invention] However, the straight pipe 2
About 1 of the power loss in fluorescent lamps
/ 3 is electrode part 11a, 11b, 12a, 12b of both ends
This is due to the reactive power that is irrelevant to the light emission, and there is a problem that the power consumption increases. Further, the electrode portion that does not contribute to light emission is usually required to have a thickness of 20 to 25 mm, which causes a problem that the dead space becomes large as indicated by the hatched portion in FIG.

In the L-shaped tube system, the straight tube 2
Although the power consumption can be suppressed by using the single-light type as compared with the light-type, the dead space becomes large because the extraction directions of the electrode portions 13a and 13b differ by 90 ° as shown in FIG. There is. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to reduce the power consumption, increase the brightness, and reduce the dead space in the edge light system by using a single fluorescent lamp.

[0007]

In order to achieve the above object, in the invention described in claim 1, the fluorescent lamp (1) and the light from this fluorescent lamp (1) are introduced from the end face and the flat portion is introduced. In an edge light type surface light source device including light guide means (2-4) for surface emission, the fluorescent lamp (1) is one lamp arranged around the light guide means (2-4). The fluorescent lamp (1) is characterized in that the lamp electrodes at one end and the other end of the fluorescent lamp (1) are arranged so that the drawing directions thereof are the same.

According to the second aspect of the present invention, the fluorescent lamp (1) and a light guide which has a rectangular shape in a plan view and which introduces light from the fluorescent lamp (1) from its side surface to emit surface light from one plane. In the edge light type surface light source device including the means (2 to 4), the fluorescent lamp (1) is
It is a one-lamp type light guide means (2-4) arranged on the outer periphery of at least three sides, and one end and the other end of the fluorescent lamp (1) have the same extraction direction of the lamp electrodes. It is characterized by being placed in.

According to a third aspect of the present invention, in the second aspect of the invention, the fluorescent lamp (1) is arranged on the outer periphery of three sides of the light guide means (2-4). , Second,
A U-shaped member formed in the order of the third side (A side, C side, B side), wherein the first and third sides (A side, B side) are in a free state, and the second side The fluorescent lamp (1) is fixed on the side (side C).

According to a fourth aspect of the invention, in the third aspect of the invention, the reflector (9) for reflecting the light of the fluorescent lamp (1) to the light guide means (2-4) is The fluorescent lamp (1) is arranged so as to cover the fluorescent lamp (1), and the second side (C side) of the fluorescent lamp (1) is fixed to the reflector (9).

The fluorescent lamp (1) is fixed to the reflector (9) by a claw 9a (fixing means) in an embodiment described later.
I am going to. Further, the reference numerals in parentheses of the above-mentioned respective means show the correspondence with the concrete means described in the embodiments described later.

[0012]

According to the invention as set forth in claims 1 to 4, the fluorescent lamp is of a one-lamp type disposed around the light guiding means, and the lamp electrodes at one end and the other end of the fluorescent lamp. Since they are arranged so that the drawing directions of are the same,
Compared to the straight-tube two-lamp system and the L-tube system, the longer the lamp is, the more the amount of light flux incident on the light guide means and the higher the light emission brightness.

Since the lamp electrodes on one end and the other end of the fluorescent lamp are drawn in the same direction, the dead space can be reduced. Further, according to the invention described in claims 3 and 4, even when the present apparatus is used in an environment where there is a lot of vibration such as a vehicle-mounted type, it is possible to prevent the problem that the fluorescent lamp is broken by the vibration.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. One embodiment of the present invention is shown in FIG. In FIG.
The fluorescent lamp 1, the light guide 2, the lamp reflector 5, and the inverter 7 are arranged as shown in the figure.
A lamp cover 6 is provided on the top. Here, the reflection film 4 and the diffusion film 3 are formed on the light guide 2 as in the conventional case.

The inverter 7 converts a DC voltage into an AC voltage (sine wave) and applies the AC voltage to the fluorescent lamp 1.
Light is generated from the fluorescent lamp 1 by the application of this AC voltage, and this light is introduced into the light guide 2 and surface-emitted from the diffusion film 3. Since the liquid crystal display element is arranged on the device shown in FIG. 1, the surface emission functions as a backlight of the liquid crystal display element.

Here, in this embodiment, the fluorescent lamp 1 is
It is a light type U-shaped lamp, and it is 3
The feature is that it is arranged around the sides. That is, as shown in FIG. 2, the fluorescent lamp 1 according to the present embodiment is of a single-lamp type, which is arranged on the outer circumference of three sides of the light guide 2, and one end and the other end of the fluorescent lamp 1 are provided. The extraction directions of the lamp electrodes 1a and 1b are the same.

Therefore, the straight pipe 2 in the edge light system
Compared to the lamp system and the L-tube system, the length of the lamp is longer, so that the amount of light flux incident on the light guide 2 is increased and the emission brightness is increased. Further, the lamp electrodes 1a at one end and the other end of the fluorescent lamp 1,
Since the pull-out direction of 1b is the same as shown in FIG. 2, the dead space indicated by the diagonal lines in the figure is reduced. FIG. 3 shows a comparison between the L-tube type in the direct type and the edge light type with respect to various parameters in the example. This comparison is based on the display area 8
Is carried out under the condition of 5 inch class, and in the edge light system, lens film is used. As shown in FIG. 3, according to this embodiment, power consumption can be reduced and high-luminance light emission can be obtained as compared with other methods.

Since the U-shaped fluorescent lamp 1 has a corner portion (referred to as R portion) having a predetermined curvature, the distance between the fluorescent lamp 1 and the light guide 2 is constant in the R portion. I won't. When the distances are not uniform, the amount of light entering the light guide 2 from the fluorescent lamp 1 becomes uneven,
Brightness unevenness may occur. Therefore, as shown in FIG. 4, by forming R portions at the corners of the light guide 2 corresponding to the R portions of the fluorescent lamp 1, the distance between the fluorescent lamp 1 and the light guide 2 is made constant, Such uneven brightness can be eliminated.

Further, when the device shown in FIG. 1 is configured as a backlight of a liquid crystal display device for a vehicle, it is necessary to properly fix and hold the fluorescent lamp 1 without cracking it in consideration of vibration of the vehicle. Therefore, as shown in FIG. 5, the lamp reflector is made of a resin having a high light reflectance, for example, polycarbonate to hold the fluorescent lamp 1, and the fluorescent lamp 1 is fixed to the lamp reflector 9. A lamp cover as shown in FIG. 1 is installed on the fluorescent lamp 1 shown in FIG.

Here, in the U-shaped fluorescent lamp 1 described above, as shown in FIG.
Such an error occurs. On the other hand, when the fluorescent lamp 1 is fixed to the lamp reflector 9 on the A side and the B side,
Stress may be applied to the R portion of the fluorescent lamp 1, and the fluorescent lamp 1 may crack due to vibration of the vehicle or the like. Therefore, the fluorescent lamp 1 is fixed to the lamp reflector 9 by the fixing portions 10a and 10b on the C side, and the A side and the B side are free. The fixing of the fluorescent lamp 1 on the fixing portions 10a and 10b is performed by using a claw 9a formed on the lamp reflector 9, as shown in FIG. With the above-described configuration, the fluorescent lamp 1 can be fixed and held without being broken even when used as a vehicle.

In the above-mentioned embodiment, the light guide plate 2 has three
Although the U-shaped fluorescent lamp 1 is provided on the outer periphery of the side, the fluorescent lamp 1 may be provided on the outer periphery of four sides of the light guide plate 2 as shown in FIG. Further, the shape of the fluorescent lamp is not limited to the U-shape, but may be a U-shape or another shape according to the shape of the light guide plate 2.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a plan configuration diagram showing an arrangement relationship between a light guide 2 and a fluorescent lamp 1 in the device shown in FIG.

FIG. 3 is a diagram showing a result of comparison between the example shown in FIG. 1 and a direct type and an L-shaped type with respect to various parameters.

FIG. 4 is a plan view showing an example of a case where an R portion is formed on the light guide 2.

FIG. 5 is a perspective view of a case where the fluorescent lamp 1 is covered with a lamp reflector 9.

FIG. 6 is an explanatory diagram for explaining a method of fixing the U-shaped fluorescent lamp 1 to the lamp reflector 9.

FIG. 7 is a partial configuration diagram showing a configuration of a part where the U-shaped fluorescent lamp 1 is fixed using a claw 9a.

8 is a plan configuration diagram showing an example in which the fluorescent lamp 1 is formed on four sides of the light guide 2. FIG.

FIG. 9 is an explanatory diagram for explaining a surface emission principle of an edge light system.

FIG. 10 is a plan configuration diagram showing a conventional straight-tube two-lamp system.

FIG. 11 is a plan configuration diagram showing a conventional L-tube system.

[Explanation of symbols]

1 ... U-shaped fluorescent lamp, 2 ... Light guide plate, 3 ... Diffusing film, 4 ... Reflective film, 5, 9 ... Lamp reflector, 6
...... Lamp cover, 7 ... Inverter.

Claims (4)

[Claims] 1. An edge light type surface light source device comprising: a fluorescent lamp; and light guide means for introducing light from the fluorescent lamp from an end face to emit light from a flat surface portion. 1 arranged around the means
A surface light source device, which is of a lamp type and is arranged such that lamp electrodes at one end and the other end of the fluorescent lamp are oriented in the same direction. 2. An edge light type surface light source device comprising: a fluorescent lamp; and a light guide means having a planar quadrangular shape for introducing light from the fluorescent lamp from a side surface of the fluorescent lamp and emitting surface light from one plane. The fluorescent lamp is of a single-lamp type, which is arranged on the outer periphery of at least three sides of the light guide means, and is arranged such that one end and the other end of the fluorescent lamp have the same drawing direction of the lamp electrodes. The surface light source device characterized by the above. 3. The fluorescent lamp is U-shaped and is arranged on the outer periphery of three sides of the light guide means and is formed in the order of first, second and third sides. The surface light source device according to claim 2, wherein the first and third sides are in a free state, and the fluorescent lamp is fixed at the second side. 4. A reflector that reflects the light of the fluorescent lamp to the light guide means is disposed so as to cover the fluorescent lamp, and the second side of the fluorescent lamp is fixed to the reflector. The surface light source device according to claim 3, which is characterized in that.