JPS6310458A - Thin-type light source - Google Patents

Abstract

PURPOSE:To make it possible to obtain a thin-type high brightness light source by such means that plural wire-shaped cathodes are aligned along a plane, an anode luminous part consisting of mesh-like electrode and white light fluorescent material layer are arranged in order faced to the wire-shaped cathode, and the anode luminous layer is excited and emitts light, being bombarded uniformly by the electrons from the wire-shaped cathodes. CONSTITUTION:Electron beam emitted from a wire-shaped cathodes 12 are accelerated without focusing conditions by mesh-like electrode 14, and being equalized on overall area, bombard a white light fluorescent material layer 16 of an anode luminous part 13, followed by areal light emission from the anode luminous part 13. As the anode luminous part 13 is applied by a high voltage of several KV, its light transfer efficiency is much higher than that of a low voltage mercury lamp and the areal luminous brightness becomes 4000ft-L-5000ft-L even at 20W-25W. White uniformity is also superior ranging + or -10%. Furthermore, brightness can be adjusted continuously from zero to the highest value by changing the voltage applied to the mesh-like electrode 14.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is suitable for use in, for example, backlights for vehicle-mounted transmissive liquid crystal displays, light sources for various other liquid crystals, light sources for copying machines, light sources for various displays, etc. Regarding a high-intensity thin light source.

[Summary of the invention]

The present invention arranges a plurality of linear cathodes along a plane,
An anode light-emitting section consisting of a mesh-like electrode and a monochromatic phosphor layer is sequentially disposed opposite to the linear cathode, and electrons from the linear cathode are uniformly impinged on the anode light-emitting section to cause excitation and light emission. This is to obtain a thin light source with high brightness.

[Conventional technology]

Conventionally, a cold cathode fluorescent discharge lamp is used as a light source for a liquid crystal display. For example, as shown in Figure 8, a plurality of cold cathode discharge lamps (10 to 15 mm in diameter) (1) are arranged in a stack, and a reflective mirror or reflective surface is placed on the rear surface to direct the light beam as far forward as possible. .

Also, on the front of the discharge lamp +1) there is mainly a milky white diffuser plate (
2) to make the light intensity distribution of the discharge lamp (1) as uniform as possible. 10u in front of the light source (3) with this structure.
Liquid crystal cells (4) are attached at intervals of ~2 (m) to form a display unit (5). (6) is a circuit board constituting a drive circuit and the like.

[Problem that the invention seeks to solve]

The above-mentioned light #f31 is basically a white fluorescent lamp and is driven at low pressure (100V), so the amount of excitation light is small (in addition, a diffuser plate (2
), it is reduced by more than half. Specifically, the diffuser plate (2)
The brightness output from is 600ft-L ~ 1000ft-L
It is.

Further, it is difficult to adjust the brightness from zero to the maximum brightness, and the discharge voltage is unstable in the low illuminance range of 20 to 30%. Further, the thickness of the above-mentioned method is 70 to 801j, which is too thick to be installed in a vehicle, especially in a dash board. Therefore, there is a demand for a thinner light source for this type of liquid crystal display.

In view of the above-mentioned points, the present invention provides a thin light source that has significantly higher luminance than the conventional light source, is thinner overall, and has a wider brightness adjustment range.

[Means for solving problems]

In the present invention, a plurality of linear cathodes (12) are arranged along a plane on the back glass (llb) side in a thin box-shaped glass tube (11), and the linear cathodes (
An anode light emitting section (13) made of a monochromatic phosphor layer is disposed on the front glass (lla) side so as to face 12), and a mesh-like electrode is arranged between the linear cathode (12) and the anode light emitting section (13). (14) to constitute a thin light source (15). For example, 6~? kV
A high voltage EHV of 20 to 50 V, for example, is applied to the mesh electrode (14).

[Effect]

In the thin light source (15) described above, the electron beams emitted from the plurality of linear cathodes (12) are
i (14) in a non-focused state, and is uniformized over the entire surface and hits the monochromatic phosphor layer (16) of the anode light emitting section (13), causing the anode light emitting section (13) to emit surface light. do. Since a high voltage of several kV is applied to the anode light emitting section (13), the light conversion efficiency is extremely high compared to a low-pressure mercury lamp, and even with 20W~2 lamps, the surface emitting luminance is ~4000ft-L~
It becomes 5000ft-L. In other words, the conventional light source 2~
Three times the brightness can be obtained. The white uniformity is also very good within 110%. Also, by varying the voltage applied to the mesh electrode (14), the brightness can be adjusted from zero! &Can be changed continuously up to high brightness. Since this light source (15) has a thin overall thickness of about 25 mm, it can be used, for example, as an in-vehicle liquid crystal backlight.

〔Example〕

Embodiments of the thin light source according to the present invention will be described below with reference to the drawings.

1, 2, and 3 show a partially cutaway front view, a partially cutaway side view, and a sectional view taken along line A--A in FIG. 1, showing a thin light source of the present invention. In this example, as shown in the figure, the front glass (lla) and the back glass (llb)
) and side glass (llc) thickness 25-301
Inside the box-shaped glass tube (11) of No. 1, there is an anode light-emitting section (13) made of a single color, for example, a white phosphor layer, and a mesh-like electrode (13) facing the anode light-emitting section (13).
4) and a plurality of linear cathodes (12) are arranged. The anode light emitting part (13) is formed by coating 1 m (16) of white phosphor on the inner surface of the front glass (ILa). A metal back layer (17) is deposited. As the white phosphor M (16), for example, '1zAQxGayo12:↑ is used for the backlight of a color liquid crystal display.
The anode preferably has a white phosphor layer made of a three-color mixture of b(x+y-5) (green phosphor), ZnS:^g (blue phosphor), and Yz(hs:Eu (red phosphor)). Light emitting part (
An anode lead (21) for supplying high voltage (anode voltage EHV) to 13) is led out to the outside through an exhaust tip-off pipe (22) provided on the side surface of the glass tube body (11) on the front glass side. In addition, anode lead (21)
The end portion (21a) of the front glass (lla) is in contact with a conductive layer made of, for example, carbon or Ag paste, which is deposited on the inner surface of the front glass (lla), and an anode is connected to the white phosphor layer (16) connected to this through this conductive layer. Voltage is supplied.

Each linear cathode (12) is formed by coating the surface of a tungsten heater with a diameter of approximately 15 μm with carbonate, which serves as an electron-emitting substance, to a thickness of 15 μm, and is arranged at a predetermined pitch along the plane of the back glass (IH+). . Each linear cathode (12) is made of, for example, 426 alloy with a thickness of 0.1 m,
It is welded and stretched between a pair of conductive supports (18a) and (18b) that are vertically erected at a distance of about 5 to 10 meters. The linear cathode (12) is stretched with appropriate tension using the spring properties of the conductive supports (18a) and (18b) so as not to loosen and cause vibration when current is applied. Each of the conductive support parts (18a) and (18b) is fixed at a sealing part between the back glass (llb) and the side glass (llc), respectively.
Lead portions (19a) and (1) extending from (18b) respectively.
9b) is led out to the outside through the sealing part. The respective lead portions (19a) and the lead portions (19b) are commonly connected to each other, for example, externally.
b) They may be commonly connected to each other.

The mesh electrode (14) is installed horizontally above the linear cathode (12) with a distance of about 5 to 7 fi. This mesh-like electrode (14) is, for example, 426 mm thick with a thickness of 0.1 mm.
It is made by etching an alloy, and is formed into a mesh with, for example, a line thickness of 0.1 mm and an interval of 2 mm. This mesh-like electrode (14) is provided with a plurality of lead parts (20) at a predetermined pitch, which also serve as support for the mesh-like electrode (14). llc) and is led out to the outside through a sealing part with the molten metal.

In addition, the conductive support part (1) that supports the linear cathode (12)
8a) (18b) and lead part (19a)
(19b) has a lead frame structure (23) as shown in FIG. 6, for example, and the mesh-like electrode (14) also has a structure (25) as shown in FIG. 7 together with the lead part (20). made in When assembling, each conductive support part (18a) of the lead frame structure (23)
and (18b), and both support parts (18a) and (1
8b) After welding and stretching the linear cathode (12) between them, a mesh-like electrode (
14) and the linear cathode lead part (19a) which was fixed at the sealing part between the back glass (llb) and the side glass (llc) at the same time in the sealing process of the glass tube body (11), and then led out to the outside. The connecting portion (24) of (19b) and the connecting portion (26) of the lead portion (20) of the mesh electrode are cut at the same time.

Linear cathode lead part (19a) (19b)
Since a through hole (27) is provided in the part corresponding to the sealing part of
2B), the thin lead parts (19a) and (19b) are firmly fixed.

Next, the operation of the thin light source (15) having such a configuration will be explained.

Figure 4 shows the drive circuit for this light source (15).
An anode voltage EHV of about ν is supplied to the anode light emitting part (13) from the terminal t1 through the anode lead (22), for example to 6 to 7, and the mesh electrode (14) is supplied from the terminal t2 through the lead part (20). For example 20-5
A voltage EB of 0V is applied. Heater voltage Ef is 6 to 1
It is about 2V. R1, R2 and R3 are stabilizing resistors of each circuit, and (31) is a switching element connected between the mesh electrode (14) and ground. Each linear cathode (12
) is accelerated by the mesh-like electrode (14) in an unfocused state and is made uniform over the entire surface.

The homogenized electron beam that has passed through the mesh electrode (14) impinges on the anode light emitting section (13), passes through the aluminum metal back layer (17), and passes through the white phosphor layer (17).
6) is excited to emit light. The surface emitting brightness at this time is 400
High brightness from 0ft-L to 5000ft-L can be obtained.

White uniformity is within ±10%. In addition, the drive signal (pulse signal) (30) is connected to the switching element (31).
) to turn on and off the switching element (31), drive the mesh electrode (14) in pulses to set the lighting time tl[, and vary the voltage EB applied to the mesh electrode (14). Accordingly, the brightness of the light source (15) can be continuously changed from zero brightness to maximum brightness.

This thin light source (15) has an extremely thin overall thickness of 25 to 30 mm and has a high surface-emitting luminance, so it can be used as a backlight for a vehicle-mounted liquid crystal display. Since light is emitted from the entire surface with a high brightness of 4000 f t-L to 5000 f t-L, the final light output increases and a bright screen can be obtained, especially for color liquid crystal plates with poor transmittance. Furthermore, since the brightness of the light source (15) can be adjusted from zero to maximum brightness, the brightness of the liquid crystal cell can be adjusted according to the state of external light. Furthermore, even though high pressure is applied to the anode generating section (13), since the lighting time is adjusted by pulse drive, an increase in the surface temperature of the anode light emitting section (13) can be suppressed.

The above table shows a performance comparison between the light source (15) of the present invention and conventional cold cathode fluorescent discharge lamps and incandescent lamps.

Table 1 Note that although the white phosphor layer was used on the upper side and was used as a white light source, it can also be applied to other monochromatic light sources.

(Effects of the Invention) According to the present invention, the surface emitting luminance is 4
At 4000 ft-L to 5000 ft-L, which is ~5 times as large, a thin light source with white uniformity within ±10% can be obtained. and,
A conventional light source unit has a thickness of 70 to 80 IIm, but the light source of the present invention has a very thin thickness of 25 to 30 IIm, so it is particularly applicable to the backlight of a vehicle-mounted transmission type liquid crystal display. Regarding the adjustment range of the brightness of the light source,
With conventional discharge type light sources, the discharge voltage is unstable in the low brightness range, making it difficult to adjust, but the light source of the present invention can continuously adjust the brightness from zero to maximum brightness.
The brightness of the liquid crystal cell can be adjusted depending on the outside light condition. It is especially effective for night lighting.

The light source of the present invention can be applied not only to the backlight of a vehicle-mounted transmissive liquid crystal display, but also to various liquid crystal light sources, copying machine light sources, various display light sources, and the like.

[Brief explanation of the drawing]

FIG. 1 is a partially broken front view showing an embodiment of a thin light source according to the present invention, FIG. 2 is a partially broken side view thereof, and FIG. 3 is a sectional view taken along line A-A in FIG. 1. , FIG. 4 is a driving circuit diagram of the light source of the present invention, and FIG. 5 is a sectional view of the main parts of the light source of the present invention.
FIG. 6 is a plan view showing an example of a lead frame structure in which the conductive support part and the lead part of the linear cathode used in the present invention are integrated, and FIG. l! FIG. 8 is a plan view showing an example of a pole, and FIG. 8 is a cross-sectional view showing an example of a liquid crystal display unit using a conventional discharge type light source. (11) is a glass tube, (12) is a linear cathode, (1
3) is an anode light emitting part, (14) is a mesh-like electrode, (
15) is a thin light source, and (16) is a phosphor layer.

Claims (1)

[Scope of Claims] A plurality of linear cathodes arranged along a plane, an anode light emitting section comprising a monochromatic phosphor layer facing the linear cathodes, and an anode light emitting section disposed between the linear cathodes and the anode light emitting section. A thin light source comprising: a mesh-like electrode formed by a mesh electrode, wherein electrons from the linear cathode uniformly impinge on the anode light emitting section to emit high-intensity light.