JP3548381B2 - Display device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid crystal display equipment, a display apparatus using a cathode ray tube with excellent small diameter and high luminance especially.
[0002]
[Prior art]
A display device such as a liquid crystal display device has a type in which a backlight is provided on the back surface of a liquid crystal display cell, and a cathode ray tube is usually used as a light source of the backlight.
FIG. 2 is a cross-sectional view of a conventionally employed cathode tube 11, in which a fluorescent layer 13 is applied and formed on the entire inner peripheral surface of a thin glass body 12. . The phosphor layer 13 is formed of a component that emits light in response to ultraviolet light. When an AC voltage is applied between the electrodes provided at both ends of the cathode tube 11, a discharge occurs in the tube 11, which reacts with mercury or the like in the tube 11 to generate ultraviolet rays. The ultraviolet rays react with the phosphor layer 13 to emit light, and this light is emitted to the outside of the cathode tube 11.
[0003]
At this time, in the phosphor layer 13, the luminance of light emission is high in the innermost part (1) where the ultraviolet rays are directly applied, and the luminance of the light emission is lower in the outermost part (2) where the ultraviolet rays are hard to reach. Therefore, as shown in FIG. 2, in the case where the phosphor layer 13 is formed over the entire inner surface of the glass body 12, the outermost light (2) having low light emission mainly passes through the glass body 12. Therefore, there is a limit in increasing the light emission luminance of the cathode tube 11.
Therefore, in order to further increase the brightness of the cathode tube 11, a method described later is adopted. In other words, by cutting off a part of the phosphor layer 13 inside the cathode tube in a lengthwise direction from one end to the other end, the light emitted from the innermost part (1) of the phosphor layer 13 can be emitted to the outside. It is like that.
[0004]
The cathode ray tube 21 shown in FIG. 3 is a sectional view of the above-described cathode ray tube. In the cathode tube 21, a phosphor layer 13 is applied and formed on the entire inner peripheral wall of the thin glass body 12, and after this application, a part of the phosphor layer 13 (within a certain range from the center of the cathode tube) is applied. It is stripped from one end to the other end along the length direction to provide a non-applied portion 25. By providing the non-coating portion 25 in this manner, light emitted in the innermost part (1) of the phosphor layer 13 is directly transmitted from the non-coating portion 25 without passing through the inside of the phosphor layer 13. The light is radiated to the outside through the glass body 12, and the brightness of the cathode tube 21 can be increased.
[0005]
[Problems to be solved by the invention]
However, recent liquid crystal display devices are required to be smaller and thinner, and the diameter of a cathode tube used tends to be smaller. On the other hand, in the cathode ray tube 21 adopting a method of forming the phosphor layer 13 on the inner wall surface of the glass body 12 and then shaving the phosphor layer 13 on the inner wall surface, it is limited to reducing the diameter. was there.
In addition, the glass body 12 must be made of a material that does not emit ultraviolet light generated inside the cathode tube 21 to the outside. When this ultraviolet ray is emitted to the outside of the cathode tube 21, it collides with the light guide plate provided in the display device main body. The light guide plate is formed of an acrylic resin, and this acrylic resin is susceptible to ultraviolet rays and, when exposed to ultraviolet rays, causes deterioration such as yellowing of the resin.
[0006]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a display device using a cathode tube which is excellent in downsizing and high brightness of a tube and suitable for downsizing and thinning.
[0007]
Another object of the present invention is to prevent components such as acrylic resin from being deteriorated by preventing ultraviolet rays from leaking to the outside.
[0008]
[Means for Solving the Problems]
The present invention provides a liquid crystal display cell, a light guide plate provided on the back side of the liquid crystal display cell, a cathode tube facing the light guide plate, and reflecting light emitted from the cathode tube in the direction of the light guide plate. In a display device provided with a reflection plate,
The cathode tube is formed by sequentially laminating a thin tubular glass body, a phosphor layer formed on the outer peripheral surface of the glass body, and a protective layer formed on the outer peripheral surface of the phosphor layer , A non-applied portion where a part of the phosphor layer is removed is provided,
The non-applied portion faces the light guide plate, and the portion on which the phosphor layer is applied faces the reflective plate at a distance,
The light from the phosphor layer passes directly through the non-coated portion and directly enters the light guide plate, and the light from the phosphor layer at the portion where the phosphor layer is applied is the reflection plate. And is indirectly incident on the light guide plate .
[0009]
In the above, the protective layer is a glass tube made of a material capable of suppressing transmission of ultraviolet rays , and the cathode tube is formed by inserting the glass body into the glass tube. Alternatively, the protective layer is water glass .
[0010]
The non-coating portion is, for example, in a range of 30 to 90 degrees from the center of the cathode tube.
[0012]
According to the present invention, the phosphor layer can be easily removed by employing a structure in which the phosphor layer is formed outside the glass body. Therefore, even if the diameter is as small as 3 mmφ or less, it is easy to adopt a configuration in which a part of the phosphor layer is removed. Further, since the protective layer is provided outside the phosphor layer, the phosphor layer does not deteriorate due to humidity or the like, and the phosphor layer does not peel off due to contact or the like.
[0013]
In this cathode ray tube, the light emitted by the reaction with the ultraviolet light inside the phosphor layer passes through the non-coated portion and is directly radiated to the outside, so that the light on the side where the non-coated portion is formed The emission luminance increases. Therefore, it is not necessary to apply an excessive drive voltage to the small-diameter cathode tube.
[0014]
In particular, if the glass body located inside the phosphor layer is made to transmit ultraviolet rays easily, the ultraviolet light generated by the discharge inside the glass body hits the phosphor layer without being attenuated, and the emission luminance can be increased. In addition, when a material that can prevent transmission of ultraviolet light is used as a protective layer outside the phosphor layer, ultraviolet light can be prevented from leaking from the non-coated portion of the phosphor layer to the outside, and for example, a light guide plate of a display device is deteriorated. Can be prevented.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described with reference to the drawings.
FIG. 1 shows a sectional view of a cathode ray tube 1 of the present invention.
The cathode tube 1 is formed by coating a phosphor layer 3 on the outer wall surface of a thin glass body 2, shaving off a part of the phosphor layer 3, and further forming a protective layer 4 on the outer wall surface of the phosphor layer 3. Is formed.
The glass body 2 is provided in the innermost layer of the cathode ray tube 1 according to the present invention. Electrodes are arranged at both ends of the thin glass body 2, and the inside of the glass body 2 contains a mercury or the like under a vacuum or a low pressure close thereto. When an AC voltage is applied between the electrodes, discharge occurs between the electrodes, and the discharge reacts with mercury or the like to generate ultraviolet rays.
[0016]
The ultraviolet rays pass through the glass body 2 and reach the phosphor layer 3 formed on the outside thereof, and the phosphor layer 3 is excited to emit light. Examples of the material of the glass body 2 include quartz glass, lead glass, soda glass, and borosilicate glass. However, the ultraviolet light generated in the glass body 2 passes through the glass body 2 and is given to the phosphor layer 3 so that the phosphor layer 3 emits light. To do this, the glass body 2 needs to be transparent to ultraviolet rays. For this reason, it is preferable that the glass body 2 use quartz glass that easily transmits ultraviolet light (ultraviolet light transmission) among the above materials.
Next, the phosphor layer 3 is formed on the outer peripheral surface of the glass body 2, and a part of the phosphor layer 3 is cut in a band shape from one end to the other end along the length direction, and the non-coated portion is formed. 5 is formed. The non-coating portion 5 is preferably formed within a range of 30 to 90 degrees from the center of the cathode tube 1. The material used for the phosphor layer 3 may be a fluorescent paint used for ordinary fluorescent lamps and the like.
[0017]
Further, a protective layer 4 for protecting the phosphor layer 3 is formed on the outer peripheral wall surface of the phosphor layer 3. The protective layer 4 may be a glass tube or the like, into which the glass body 2 coated with the phosphor layer 3 may be inserted, or the outer peripheral surface of the phosphor layer 3 may be coated with water glass or the like. 4 may be formed. As a material of the protective layer 4, lead glass, soda glass, borosilicate glass, quartz glass, or the like can be used, but ultraviolet rays generated in the glass body 2 pass through the non-coated portion 5 and further pass through the protective layer 4. In order not to radiate much to the outside, it is preferable to use, as the protective layer 4, a material that can suppress the transmission of ultraviolet rays other than lead glass, soda glass, borosilicate glass, etc., that is, quartz glass.
[0018]
When an AC voltage is applied between the electrodes provided on both sides of the cathode tube 1, ultraviolet rays are emitted by the discharge inside the glass body 2 and mercury, and the ultraviolet rays excite the phosphor layer 3 to generate visible light. appear. This light is emitted outside through two routes α and β. In one path α, the ultraviolet light passes through the glass body 2 and hits the innermost part (1) of the phosphor layer 3 so that the innermost part (1) emits light. The light passes through the non-coating portion 5 and passes through the protective layer 4. In the other path β, the light from the light emitted from the innermost part (1) of the phosphor layer 3 to the light emitted from the outermost part (2) passes through the phosphor layer 3 in a portion other than the non-coated portion 5, and The light is emitted through the protective layer 4 to the outside.
[0019]
As described above, in the innermost part {circle around (1)} of the phosphor layer 3, ultraviolet light generated in the glass body 2 directly excites the phosphor layer, so that the light emission luminance is high, and this light is directly radiated to the outside. The light in the path α has higher luminance than the light in the path β that passes through the phosphor layer 3. Therefore, light that is brighter on the α side than on the β side can be obtained.
In addition, since the phosphor layer 3 is formed outside the glass body 2, the diameter of the tube can be further reduced as compared with the conventional method in which the phosphor layer 3 is formed inside the glass tube. The part 5 is also easy to form. Further, by providing the non-coating portion 5, light reflected inside the cathode tube 1 can be emitted to the outside, so that light with higher luminance than before can be obtained.
[0020]
Further, as described above, by using the cathode tube 1 of the present invention as a backlight of a liquid crystal display device, a decrease in luminance caused by a reduction in the diameter of the cathode tube 1 due to a reduction in the size and thickness of the device body is compensated. Is what you can do.
Further, in order to improve the luminance, a large current is applied to the cathode tube 1 to increase the amount of emitted electrons, thereby preventing the phosphor layer 3 from being deteriorated. It is possible to prevent a reduction in the life of the tube, a reduction in the luminous flux due to a thin light source, and a reduction in the efficiency due to an increase in the impedance of the cathode tube.
[0021]
Next, FIG. 4 is a sectional view of an example of a display device provided with the cathode tube of the present invention.
Reference numeral 30 in FIG. 4 denotes a display device main body. The display device body 30 includes a liquid crystal display cell 31, a light diffusion sheet 32, a light guide plate 33 formed of a transparent resin such as acrylic, a cathode tube 1, 1 and a reflection plate 34 arranged in order from the front to the back. In this embodiment, the cathode tubes 1 and 1 of the present invention are disposed between the light guide plate 33 and the reflection plate. In this case, the non-coating portion 5 side of the cathode tubes 1 and 1 is directed to the light guide plate 33.
The liquid crystal display cell 31 is obtained by injecting a liquid crystal material into a gap between two transparent glass substrates. The materials and the like of the liquid crystal display cell 31, the light diffusion sheet 32, the light guide plate 33, and the reflection plate 34 may be those used in an ordinary liquid crystal display device. Although the number of the cathode tubes 1 is two in FIG. 4, the number is not limited to these, and one or more cathode tubes may be provided.
[0022]
As shown in FIG. 4, a cathode ray tube 1, 1 used as a light source of a backlight of a display device has high brightness light (path) emitted from the front of the cathode ray tube 1, 1 as shown by an arrow. The light of α is guided to the light guide plate 33 as it is, and the light (light of the path β) emitted behind the cathode tubes 1 and 1 is reflected via the reflection plate 34 and guided to the light guide plate 33.
In the example shown in FIG. 4, high-luminance light on the path α is given to the light guide plate 33 and the liquid crystal display cell 31 to form a high-luminance backlight. Since the light is reflected and provided to the light guide plate 33 and the liquid crystal display cell 31, the light emitted from the cathode tubes 1 and 1 can be used without waste, thereby efficiently using the light as the backlight of the light source of the liquid crystal display device. it can.
[0023]
FIG. 5 shows another example of the display device of the present invention, in which the light guide plate 33 is changed to a modified type. The light guide plate 33 has the cathode tube 1 opposed to one end, and gradually becomes thinner from the end to the tip, and the liquid crystal display cell 31 side is flat. A reflection plate 34 is provided on the back surface of the cathode tube 1 facing one end of the light guide plate 33. Light emitted from the cathode tube 1 is irregularly reflected inside the light guide plate 33 and is provided to the light diffusion sheet 32 and the liquid crystal display cell 31.
Also in this display device, the non-coating portion 5 of the cathode tube 1 is directed to the end face of the light guide plate 33. Since the diameter of the cathode tube 1 can be reduced, the light guide plate 33 can also be made thin, and a thin display device as a whole can be obtained. Also, similarly to the one shown in FIG. 4, the light of the high-luminance path α can be made to enter the light guide plate 33, and the light of the path β is reflected by the reflection plate 34 and made to enter the light guide plate 33. Can be. Accordingly, a backlight with high light use efficiency and high luminance can be formed.
[0024]
【The invention's effect】
As described above, in the present invention, by adopting a configuration opposite to the conventional configuration in which the phosphor is formed on the outer surface of the cathode tube, it is possible to eliminate the inconvenience caused by scraping off the phosphor applied to the inside of the tube. Accordingly, the diameter of the cathode tube can be further reduced, and light returning to the inside of the cathode tube can be taken in by making a part of the phosphor a non-coating portion, thereby further increasing the brightness of the light. What you can get.
[0025]
By using the cathode tube of the present invention as a backlight light source of a liquid crystal display device, it is possible to contribute to downsizing and thinning of the liquid crystal display device main body.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a cathode ray tube of the present invention;
FIG. 2 is a sectional view showing a conventional cathode tube;
FIG. 3 is a sectional view showing another conventional cathode ray tube;
FIG. 4 is a sectional view of a display device provided with a cathode ray tube according to the present invention;
FIG. 5 is a sectional view of another display device provided with a cathode ray tube according to the present invention;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cathode tube 2 Glass body 3 Phosphor layer 4 Protective layer 5 Non-coating part 30 Display body 31 Liquid crystal display cell 32 Light diffusion sheet 33 Light guide plate 34 Reflector

Claims (4)

A liquid crystal display cell, a light guide plate provided on the back side of the liquid crystal display cell, a cathode tube facing the light guide plate, and a reflector for reflecting light emitted from the cathode tube in the direction of the light guide plate. In the provided display device,
The cathode tube is formed by sequentially laminating a thin tubular glass body, a phosphor layer formed on the outer peripheral surface of the glass body, and a protective layer formed on the outer peripheral surface of the phosphor layer , A non-applied portion where a part of the phosphor layer is removed is provided,
The non-applied portion faces the light guide plate, and the portion on which the phosphor layer is applied faces the reflective plate at a distance,
The light from the phosphor layer passes directly through the non-coated portion and directly enters the light guide plate, and the light from the phosphor layer at the portion where the phosphor layer is applied is the reflection plate. A display device , which is reflected by the light guide and indirectly enters the light guide plate . The display device according to claim 1, wherein the protective layer is a glass tube made of a material capable of suppressing transmission of ultraviolet light , and the cathode tube is formed by inserting the glass body into the glass tube . The protective layer according to claim 1 Symbol placement of the display device is water glass. Display device according to any one of 3 to the claims 1 to non-application portion is 30 to 90 degrees from the cathode tube center.

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