JPH07114904A - Fluorescent discharge lamp for backlight source - Google Patents

Abstract

(57) [Summary] [Object] To provide a fluorescent discharge lamp for a backlight light source, which is improved in light utilization efficiency and is suitable for a liquid crystal display device having a simple structure. [Structure] A fluorescent layer 20a of a fluorescent discharge lamp used as a backlight source of a liquid crystal display device has a strip-shaped fluorescent layer 20d applied along the side surface of a light guide on the inner wall surface of the fluorescent layer 20d. A reflective layer 20c was provided on the outer wall surface except for.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar light source, particularly a so-called backlight light source used for illuminating a liquid crystal display device or the like, and more particularly to a fluorescent discharge lamp for a backlight light source having a significantly improved illumination efficiency. .

[0002]

2. Description of the Related Art Liquid crystal display devices are known to be of a transmissive type or a reflective type, depending on the illumination system. In particular, the transmissive type is widely adopted for image display of a simple matrix type STN liquid crystal display device or an active matrix type TFT liquid crystal display device.

A transmissive liquid crystal display device is provided with a light source device (backlight light source) for emitting planar illumination light on the back surface of a liquid crystal display element, and projects light having a uniform distribution on an effective screen area of the liquid crystal display element. Then, the light transmitted through the liquid crystal display element is observed.

FIG. 12 is a developed perspective view for explaining a structural example of a liquid crystal display device, in which 1 is a liquid crystal display element, 2 is a backlight light source, 3 is a printed circuit board, 4 is a frame, and 6 and 7 are spacers. .

In the structural example of FIG. 1, the backlight source 2 is a cylindrical fluorescent discharge lamp (for example, a straight tube cold cathode fluorescent lamp) 20, a light guide plate 21 made of a transparent material adjacent to the fluorescent discharge lamp 20, and a light guide plate. It is mainly composed of a reflection plate 22 installed on the back surface of 21 and a diffusion plate 23 installed on the front surface of the light guide plate 21.

The printed circuit board 3 is a control IC for the cold cathode fluorescent lamp 20.
31, electronic circuit parts such as a driving IC 32 for driving the liquid crystal display element are mounted, and a slit 10 for fixing the frame is formed.

The frame 4 has a rim 41 for fixing the periphery by exposing the effective screen area of the liquid crystal display device, and also has a fixing piece 9 for inserting and fixing it in a slit 10 formed in a printed circuit board.

The fluorescent discharge lamp 20 constituting the backlight light source 2 is installed close to the side surface of the light guide plate 21, and is connected to the power source through the socket 24, the power supply line 25, and the connector 28.

The emitted light of the fluorescent discharge lamp 20 propagates through the light guide plate 21, is reflected by the reflection plate 22, and is directed toward the diffusion plate 23.

The fluorescent discharge lamp 20 is covered with a shield cover 26 fixed with screws 27 so that unnecessary light does not reach the liquid crystal display element or the like.

FIG. 13 is a schematic cross-sectional view for explaining an example of the arrangement of each member constituting the liquid crystal display device, and the same reference numerals as those in FIG. 12 correspond to the same parts.

As shown in FIG. 1, the backlight source 2 is provided with a fluorescent discharge lamp 20 on the side surface of a light guide plate 21 formed of a transparent material having a predetermined thickness such as an acrylic resin plate. The light L emitted from 20 is directed to the liquid crystal display element 1 from the diffusion plate 23, and is reflected by the reflection plate 22 to be directed from the diffusion plate 23 to the liquid crystal display element 1 direction to illuminate the liquid crystal display element 1. , Is configured to observe the image formed on the liquid crystal display element on the frame 4 side.

Conventionally, a member having a reflecting function is provided outside, but the internal loss of the fluorescent discharge lamp is large and the light utilization efficiency is extremely low.

The above-mentioned backlight light source includes the light guide plate 21.
The light of the fluorescent discharge lamp is directed to the liquid crystal display element by using the light guide body and the reflecting plate and the diffusing plate. There is also a structure in which the surface is used or the light guide plate is removed and an air layer is used as a light guide to propagate light.

The prior art relating to this type of liquid crystal display device is disclosed, for example, in Japanese Examined Patent Publication No. 51-13.
666 and JP-A-63-309921 can be mentioned.

[0016]

In the above-mentioned prior art, the fluorescent discharge lamp constituting the backlight light source is formed by applying a phosphor layer on the entire inner wall of a cylindrical tube. The visible light, which is emitted by stimulating the light with ultraviolet rays, is introduced into the light guide plate or the light guide body composed of the air layer.

Therefore, the light emitted in the direction of the light guide is
The light is mainly emitted from the portion of the fluorescent discharge lamp located on the light guide side, and most of the other light returns to the phosphor layer itself even if a reflection plate is provided outside. However, there is a problem that it is difficult to reduce the power consumption of the liquid crystal display device because it is attenuated by the absorption of light and its light utilization efficiency is extremely low.

Further, in the conventional backlight light source, it is necessary to install, as an essential constituent member, a light-shielding plate that also serves as a reflector around the light emitted from the fluorescent discharge lamp except for the portion facing the light guide. However, there is a problem that the number of parts is large and assembly is complicated.

An object of the present invention is to solve the above-mentioned problems of the prior art, improve the light utilization efficiency of a fluorescent discharge lamp, and provide a fluorescent discharge lamp for a backlight source suitable for a liquid crystal display device having a simple structure. To do.

[0020]

In order to achieve the above object, the invention according to claim 1 of the present invention is a fluorescent discharge lamp used as a backlight source of a liquid crystal display device, wherein the tube of the fluorescent discharge lamp is used. The inner wall surface of the body has a strip-shaped phosphor layer applied along the longitudinal direction thereof, and a reflective layer is provided on either the outer wall surface or the inner wall surface of the tubular body excluding the phosphor layer. Characterize.

The invention according to claim 2 of the present invention is
In a fluorescent discharge lamp used as a backlight light source of a liquid crystal display device, on the outer wall surface of the tube body of the fluorescent discharge lamp, a strip-shaped phosphor layer applied along the longitudinal direction thereof,
A reflecting layer is provided on either the outer wall surface or the inner wall surface of the tubular body excluding the phosphor layer.

Further, according to a third aspect of the present invention, in a fluorescent discharge lamp used as a backlight light source of a liquid crystal display element, either the inner wall surface or the outer wall surface of the tube body of the fluorescent discharge lamp is provided. It has a strip-shaped phosphor layer applied along its longitudinal direction, and a reflective layer is provided on either the outer wall surface or the inner wall surface of the tubular body excluding the phosphor layer, and the phosphor layer and the liquid crystal. It is characterized in that a transparent member is embedded between the light guide plate constituting the display element.

[0023]

In the structure of claim 1, the strip-shaped phosphor layer applied to the inner wall surface of the tube body of the fluorescent discharge lamp so as to face the side surface of the light guide is the inside of the fluorescent discharge lamp. The ultraviolet light excited and emitted by is converted into visible light. At this time, the ultraviolet rays are reflected by the reflection layer provided on either the outer wall surface or the inner wall surface excluding the phosphor layer, and substantially the entire amount thereof is collected in the phosphor layer, so that the wavelength conversion efficiency by the phosphor layer is improved. It is possible to introduce high-luminance visible light into the light guide. further,
The light emitted from the phosphor layer toward the inner surface can also be reflected by the reflective layer provided on either the outer wall surface or the inner wall surface to contribute to the increase in the amount of light.

Further, in the structure of claim 2, the strip-shaped phosphor layer formed on the outer wall surface of the glass tube of the cold cathode tube along the side surface of the light guide also has the structure of claim 1. Works the same way.

Further, in the structure of claim 3, the transparent member embedded between the phosphor layer and the light guide forming the liquid crystal display element is an air present between the phosphor layer and the light guide plate. Light reflection at the boundary with the layer is reduced to improve light utilization efficiency.

The present invention is not limited to the above-mentioned constitution, and the present invention is not limited to the backlight light source for the liquid crystal display device, but can be applied to the surface light source of other electronic devices and the like. It is a thing.

[0027]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a partially broken perspective view illustrating a first embodiment of a fluorescent discharge lamp for a backlight light source according to the present invention, in which 20 is a fluorescent discharge lamp and 20a is a vacuum container for the fluorescent discharge lamp. The tube body, 20b is its power supply terminal, 20c is a reflection layer, and 20d is a band-shaped phosphor layer.

FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1, and the same reference numerals as those in FIG. 1 correspond to the same parts, and 21 denotes a light guide plate or a light guide body made of an air layer. Is. 1 and 2, the fluorescent discharge lamp 20 is composed of a tube body 20a having power supply terminals 20b at both ends, and a phosphor layer 20d is applied to a strip-shaped region having a width B along the longitudinal direction inside the tube. .

On the outer wall of the tube excluding the coating area of the phosphor layer 20d, a light reflecting layer 20c is formed by vapor deposition or coating of aluminum or the like, or by sticking a light reflecting material such as aluminum foil.

As shown in FIG. 2, it is preferable that the width B of the strip-shaped phosphor layer is approximately equal to the thickness of the light guide 21 arranged in the vicinity thereof, but the width B is not necessarily limited to this. However, the width B and the thickness of the light guide 21 may be different.

In this embodiment, the phosphor layer 20d of the fluorescent discharge lamp 20 is exposed to the ultraviolet rays generated by the excitation of mercury inside the fluorescent discharge lamp, and the ultraviolet rays generated by the reflecting layer 20c are almost entirely incident on the fluorescent layer 20d. Bright visible light can be introduced into the light guide 21.

That is, the conversion efficiency of the phosphor layer of the cold cathode fluorescent lamp becomes extremely high, and a bright liquid crystal display device can be constructed.

FIG. 3 is a cross-sectional view of an essential part for explaining a second embodiment of a fluorescent discharge lamp for a backlight light source according to the present invention,
The same reference numerals as those in FIG. 2 correspond to the same parts.

In this embodiment, the phosphor layer 20d is applied to a strip-shaped region having a width B along the longitudinal direction inside the pipe of the pipe body 20a, and the inner wall of the pipe excluding the application region of the phosphor layer 20d. In addition, the light reflection layer 2 formed by forming a light reflection material such as vapor deposition or coating of aluminum or the like similar to the above embodiment.
It has 0c.

Also in this embodiment, as in the above embodiment, the utilization efficiency of the phosphor layer is increased, and a bright backlight light source with low power can be obtained.

FIG. 4 is a cross-sectional view of an essential part for explaining a third embodiment of the fluorescent discharge lamp for the backlight light source according to the present invention.
The same reference numerals as those in FIG. 2 correspond to the same parts.

In this embodiment, the phosphor layer 20d in the embodiment shown in FIG. 2 is applied to the outer wall of the tubular body 20a in a band-shaped region having a width B along the longitudinal direction thereof.

A protective film 20e is coated on the phosphor layer 20d as necessary to prevent the phosphor layer 20d from being deteriorated in the air. That is, the phosphor 20d
The above-mentioned protective layer 20e is not required as long as it does not deteriorate in the presence of air.

The outer wall of the tubular body 20a excluding the coating area of the phosphor layer 20d is provided with a light reflecting layer 20c formed by vapor deposition or coating of aluminum, for example, or by pasting a light reflecting material such as aluminum foil. .

In this embodiment, the reflective layer 20c
May be provided inside the tubular body 20a as in FIG.

According to this embodiment, it is possible to obtain the same effects as in the above-mentioned respective embodiments, and since the phosphor layer 20d is easily applied, the manufacturing work of the fluorescent discharge lamp can be simplified and the cost can be reduced. It can be reduced significantly.

FIG. 5 is a cross-sectional view of an essential part for explaining a fourth embodiment of the fluorescent discharge lamp for the backlight light source according to the present invention.
The same reference numerals as those in FIG. 2 correspond to the same parts.

In this embodiment, the air layer interposed between the phosphor and the light guide in FIGS. 2 to 4 is removed, and reflection at the boundary with the air layer is reduced to improve the light utilization efficiency. is there. That is, FIG. 5 shows the structure of FIG. 4 in which a space between the phosphor layer 20d and the light guide plate is filled with a transparent member 20h such as a gel of curable silicone resin or a resin such as polyester. is there. The structure of the fluorescent discharge lamp or the light guide plate lamp due to mechanical distortion between the fluorescent discharge lamp and the light guide due to temperature change or mechanical stress due to the flexibility of the transparent member such as gel or resin. It is possible to avoid damage to the members.

Needless to say, the gel or resin described above can be applied to the structure shown in FIG. 2 or FIG.

FIG. 6 is a cross-sectional view of an essential part for explaining a fifth embodiment of a fluorescent discharge lamp for a backlight light source according to the present invention,
20d 'is a phosphor layer, 20e' is a transparent protective layer, and the same reference numerals as those in FIG. 2 correspond to the same portions.

In this embodiment, the fluorescent discharge lamp does not have a fluorescent substance, but instead, a side face of the light guide 21 facing the fluorescent discharge lamp is coated with a fluorescent substance layer 20d '.

When the phosphor 20d 'is deteriorated in the air, the protective film 20e' is applied, and when the phosphor 20d 'is deteriorated in the air, the phosphor layer 20 is formed.
It prevents the deterioration of d '. If the phosphor does not deteriorate as described above, the protective layer is not necessary.

In the fluorescent discharge lamp, for example, vapor deposition of aluminum or the like is performed so that a band-shaped transparent portion is left in a region B of the tube body 20a facing the side of the light guide body 21 facing the phosphor layer 20d '. The light reflection layer 20c is provided by coating or adhering a light reflection material such as aluminum foil.

In this embodiment, the reflective layer 20c
May be provided inside the glass tube as in FIG.

According to this embodiment, it is possible to obtain the same effect as each of the above-mentioned embodiments, and since the phosphor layer 20d is easily applied, the work of the cold cathode tube can be simplified and the cost can be reduced. Can be significantly reduced.

FIG. 7 is a cross-sectional view of an essential part for explaining a sixth embodiment of the fluorescent discharge lamp for the backlight light source according to the present invention.
The same reference numerals as in FIG. 6 correspond to the same parts.

In this embodiment, as in FIG. 6, the fluorescent discharge lamp does not have a fluorescent body, but instead, the side surface of the light guide 21 facing the fluorescent discharge lamp is coated with a fluorescent body 20d '. .

The phosphor 20d 'is coated with a protective film 20e' to prevent deterioration of the phosphor layer 20d 'in the air. It should be noted that this protective film 20e 'is also unnecessary when the phosphor is not deteriorated, as in the above embodiment.

The fluorescent discharge lamp is made of, for example, a metal plate made of aluminum or the like so as to leave a band-shaped transparent window portion in the region B of the tube body 20a facing the side surface of the light guide plate 21 facing the phosphor layer 20d '. A reflecting mirror 20c 'made of a member coated with a reflecting material such as aluminum is provided. The reflecting mirror 20c 'is not limited to the cylindrical shape (circular cross section) as shown, but may be a reflecting structure member having a rectangular cross section, an elliptical cross section, or any other shape.

FIG. 8 is a sectional view showing the principal part of a fluorescent discharge lamp for a backlight light source according to a seventh embodiment of the present invention.
Reference numeral 20f denotes a glass tube forming the reflection member, and the same reference numerals as those in FIG. 2 correspond to the same portions.

In this embodiment, the fluorescent discharge lamp does not have a fluorescent substance, but instead, the fluorescent discharge lamp is inserted in the strip-shaped region facing the light guide plate 21 on the inner surface of the tubular body 20f constituting the reflecting member. A phosphor layer 20e is formed, and on the outer surface of the tubular body 20f,
A reflective film 20c formed like a transparent window is provided in a region B facing the light guide plate 21.

According to the embodiments described with reference to FIGS. 7 and 8, it is not necessary to form a phosphor layer or a reflection layer in the fluorescent discharge lamp, and the tube body 20f and the fluorescent discharge lamp which constitute the reflecting member are formed. Since it is assembled as a separate member, it becomes easy to replace the fluorescent discharge lamp when it deteriorates.

FIG. 9 is a sectional view of an essential part for explaining an eighth embodiment of the fluorescent discharge lamp for the backlight light source according to the present invention.
The same reference numerals as those in FIG. 2 correspond to the same parts.

In this embodiment, the fluorescent discharge lamp has a flat portion 20g on one side thereof along the longitudinal direction of the tube, and a fluorescent layer 20d on the inner wall of the flat portion 20g. Other than the configuration, the configuration is similar to that of FIG.

FIG. 10 is a cross-sectional view of an essential part for explaining a ninth embodiment of the fluorescent light source for a backlight light source according to the present invention, and the same reference numerals as those in FIG. 9 correspond to the same parts.

In this embodiment, the flat portion in the embodiment shown in FIG. 9 is formed substantially at the center of the tube of the fluorescent discharge lamp, and the volume of the fluorescent discharge lamp can be greatly reduced.

FIG. 11 is a sectional view of a principal part for explaining a tenth embodiment of a fluorescent light source for a backlight source according to the present invention, and the same reference numerals as those in FIG. 9 correspond to the same parts.

In this embodiment, the tube body of the fluorescent discharge lamp has a substantially parabolic cross section, and the excited ultraviolet rays can be more efficiently concentrated on the phosphor layer 20d, and the wavelength conversion efficiency is further improved. Can be made.

The present invention is not limited to the above embodiments, and these configurations can be combined appropriately.

As described above, according to the configurations of the respective embodiments of the present invention, the brightness of the fluorescent discharge lamp can be significantly improved, so that it is possible to provide a liquid crystal display device having a bright screen with low power consumption.

[0067]

As described above, according to the present invention,
Since the luminous efficiency of fluorescent discharge lamps or the utilization efficiency of phosphors can be increased to significantly improve the brightness, fluorescent discharge lamps for backlight light sources for liquid crystal display devices with low power consumption and bright screens and other surface light sources. Can be obtained.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a cold cathode tube for explaining a first embodiment of a backlight light source according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view of an essential part for explaining a second embodiment of a backlight light source according to the present invention.

FIG. 4 is a sectional view of an essential part for explaining a third embodiment of a backlight light source according to the present invention.

FIG. 5 is a sectional view of an essential part for explaining a fourth embodiment of a backlight light source according to the present invention.

FIG. 6 is a cross-sectional view of essential parts for explaining a fifth embodiment of a backlight light source according to the present invention.

FIG. 7 is a cross-sectional view of essential parts for explaining a sixth embodiment of a backlight light source according to the present invention.

FIG. 8 is a sectional view of an essential part for explaining a seventh embodiment of a backlight light source according to the present invention.

FIG. 9 is a sectional view of an essential part for explaining an eighth embodiment of a backlight light source according to the present invention.

FIG. 10 is a cross-sectional view of essential parts for explaining a ninth embodiment of a backlight light source according to the present invention.

FIG. 11 is a sectional view of an essential part for explaining a tenth embodiment of a backlight light source according to the present invention.

FIG. 12 is a developed perspective view illustrating a structural example of a liquid crystal display device.

FIG. 13 is a schematic cross-sectional view illustrating an arrangement example of each member that configures the liquid crystal display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal display element 2 Backlight light source 3 Printed circuit board 4 Frame 6,7 Spacer 9 Fixing piece 10 Slit 20 Fluorescent discharge lamp 20a Tubular body 20b Power supply terminal 20c Reflective layer 20d Strip fluorescent layer 21 Light guide (light guide plate) 22 Reflection Plate 23 Diffusion plate 24 Socket 25 Power supply line 28 Connector 31 Control IC 32 Drive IC 41 Rim.

Claims (3)

[Claims] 1. A fluorescent discharge lamp used as a backlight light source of a liquid crystal display device, comprising a strip-shaped fluorescent layer applied along the longitudinal direction on an inner wall surface of a tube body of the fluorescent discharge lamp, A fluorescent discharge lamp for a backlight light source, comprising a reflective layer on either the outer wall surface or the inner wall surface of the tube excluding the phosphor layer. 2. A fluorescent discharge lamp used as a backlight light source of a liquid crystal display device, comprising a strip-shaped phosphor layer applied along a longitudinal direction on an outer wall surface of a tube body of the fluorescent discharge lamp, A fluorescent discharge lamp for a backlight light source, comprising a reflective layer on either the outer wall surface or the inner wall surface of the tube excluding the phosphor layer. 3. A fluorescent discharge lamp used as a backlight light source of a liquid crystal display device, wherein strip-shaped fluorescent light is applied to either the inner wall surface or the outer wall surface of the tube body of the fluorescent discharge lamp along the longitudinal direction thereof. A body layer is provided, and a reflection layer is provided on either the outer wall surface or the inner wall surface of the tubular body excluding the phosphor layer, and between the phosphor layer and the light guide forming the liquid crystal display element. A fluorescent discharge lamp for a backlight light source, wherein a transparent member is embedded.