WO2008059639A1

WO2008059639A1 - Electrode part, light source, illuminating device, and liquid crystal display

Info

Publication number: WO2008059639A1
Application number: PCT/JP2007/064337
Authority: WO
Inventors: Yasuhiro Furusawa
Original assignee: Sharp Kabushiki Kaisha
Priority date: 2006-11-14
Filing date: 2007-07-20
Publication date: 2008-05-22

Abstract

An electrode part (1), is installed in a light source in which an electron-emissive material (7) is heated to emit thermions for causing arc discharge for light emission. The electrode part is equipped with a filament (5) for heating the electron-emissive material (7) and a plate electrode (2) for performing arc discharge, separetely. By such a constitution, an electrode part for suppressing the breakage of an electrode, a light source, an illuminating device, and a liquid crystal display can be provided.

Description

Specification

Electrode unit, light source, illumination device and liquid crystal display device

Technical field

TECHNICAL FIELD [0001] The present invention relates to an electrode unit that suppresses disconnection of an electrode, a light source including the electrode unit, an illumination device including the light source, and a liquid crystal display device using the illumination device as a backlight.

[0002] A knock light is used as a light source for displaying an image on a liquid crystal display panel (hereinafter referred to as an LCD panel) such as a liquid crystal TV, a liquid crystal display, and a liquid crystal monitor, and supplies light to the entire surface of the LCD panel. Have a role to play. The light emitting elements used in such backlights are fluorescent lamps such as hot cathode fluorescent lamps (HCFL elements) and cold cathode fluorescent lamps (CCFL elements), LED elements, and the like. Etc.

[0003] A hot cathode fluorescent lamp is superior to other light emitting elements in terms of luminous efficiency, and is widely used because high luminance light can be obtained at a relatively low voltage. In a conventional thermal cathode fluorescent lamp, a filament electrode is provided inside both ends of a cylindrical glass tube whose inner wall surface is coated with a phosphor, and the filament electrode has an electron emission material such as BaO'CaO.SrO. Emissive material is retained.

A specific configuration of a conventional hot cathode fluorescent lamp will be described with reference to FIG. FIG. 7 is a diagram showing a schematic configuration of a conventional hot cathode fluorescent lamp 101. As shown in FIG. 7, the hot cathode fluorescent lamp 101 is composed of a glass tube 102, a filament electrode 103, a metal guide 104, and a force. The openings at both ends of the glass tube 102 are inserted while being held by the coiled filament electrode 103 force S and the metal guide 104 coated with an electron radioactive substance! As the filament electrode 103, an electric wire made of tungsten is preferably used. As the metal guide 104, a dumet wire is preferably used.

[0005] The mechanism by which the hot cathode fluorescent lamp 101 emits light will be described below. If the current is passed through the filament electrode 103 before the hot cathode fluorescent lamp 101 starts lighting, Thermal electrons are emitted from the active substance into the glass tube 102. When a high voltage is applied between the filament electrodes 103 provided inside both ends of the glass tube 102, thermoelectrons are attracted by the anode and discharge starts, and ultraviolet rays are emitted when colliding with mercury enclosed inside. Is done. The ultraviolet rays excite the phosphor coated on the inner wall surface of the glass tube 102 and emit visible light unique to the phosphor.

[0006] However, in the conventional hot cathode fluorescent lamp 101, the electron radioactive material is depleted due to exhaustion or scattering of the filament electrode 103, or the filament electrode 103 is disconnected. The life is shortened compared to.

[0007] The conventional filament electrode 103 cannot apply a large amount of electron-emitting material.

The electron radioactive substance is a source of thermionic electrons, and is evaporated by a phenomenon such as sputtering during the arc discharge. When the electron radioactive substance is exhausted, the hot cathode fluorescent lamp 101 cannot emit light. Therefore, in the configuration of the filament electrode 103, since only a small amount of the electron-emitting material can be applied, the life is shortened.

[0008] In order to extend the life of the hot cathode fluorescent lamp, Patent Document 1 describes a technique that increases the surface area of an electrode and makes it possible to apply a large amount of an electron-emitting material. The electrode described in Patent Document 1 is a holo electrode in which a tungsten wire is wound so as to have a holo structure. In addition, as an electrode having a large surface area, for example, an ultra-fine wire of about 0.2 mm is spirally wound, and the wire is further spirally wound, or a double-coil or double-coil wire is further spiraled. There is a triple coil system wound in a shape.

Next, a conventional drive circuit 106 for driving the hot cathode fluorescent lamp 101 in the illumination device 105 including the hot cathode fluorescent lamp 101 will be described with reference to FIG. FIG. 8 is a diagram showing a main configuration of a conventional drive circuit 106. As shown in FIG. 8, the drive circuit 106 includes a control unit 107, a switching circuit 108, and a direct IJLC oscillation device 109.

[0010] The drive circuit 106 controls the voltage applied to the direct IJLC oscillation device 109 by switching the ON / OFF of the switching circuit 108 composed of two FETs by the control unit 107, so that the hot cathode fluorescent lamp 101 is controlled. The drive circuit 106 supplies a current to the filament electrode 103 in order to heat the electron-emitting material. On this occasion, A voltage is applied to the filament electrodes 103 at both ends of the hot cathode fluorescent lamp 101, and a glow current is generated. When a glow current is generated in the hot cathode fluorescent lamp 101, there is a high possibility that the filament electrode 103 is disconnected due to electrical stress, sputtering, or the like, and the life is shortened. Therefore, it is preferable to suppress the glow current generated in the hot cathode fluorescent lamp 101.

Therefore, conventionally, like the lighting device 110 shown in FIG. 9, the filament electrode 103 is independently driven to suppress the occurrence of a glow current in the hot cathode fluorescent lamp 101. The configuration of the illumination device 110 will be described with reference to FIG. FIG. 9 is a diagram showing a main configuration of the illumination device 110. As shown in FIG.

As shown in FIG. 9, the illumination device 110 includes a hot cathode fluorescent lamp 101, a control unit 111, a preheating transformer 112, and a discharge transformer 113. The control unit 111 is connected to the filament electrode 103 of the hot cathode fluorescent lamp 101 via two preheating transformers 112 and one discharge transformer 113.

[0013] Specifically, in each of the two preheating transformers 112, two wires on the secondary side of the preheating transformer 112 are connected to both ends of the filament electrode 103 at one end of the hot cathode fluorescent lamp 101. . Also, the two electric wires on the secondary side of the discharge transformer 113 are connected to the filament electrodes 103 at both ends of the hot cathode fluorescent lamp 101, respectively.

Here, a driving method for suppressing the glow current generated in the hot cathode fluorescent lamp 101 in the illumination device 110 will be described. First, the control unit 111 controls the primary side of the preheating transformer 112, supplies current to the secondary side, and supplies current to the filament electrode 103. After the filament electrode 103 reaches a desired temperature, the control unit 111 controls the primary side of the discharge transformer 113 to apply a high voltage to the secondary side, and the filaments at both ends of the hot cathode fluorescent lamp 101 A voltage is applied to the electrode 103. As a result, the filament electrode 103 can be driven by a sequence in which arc discharge occurs after heating the electron-emitting material, and the glow current generated in the hot cathode fluorescent lamp 101 can be suppressed.

Patent Document 1: Japanese Patent Publication “Japanese Patent Laid-Open No. 6-52827 (Publication Date: February 25, 1994)”

Disclosure of the invention [0015] The hollow electrode, the double coil type electrode, and the triple coil type electrode described in Patent Document 1 described above have a large surface area of the electrode, so that a large amount of electron-emitting material is applied to the electrode. Is possible. As a result, the lifetime of the hot cathode fluorescent lamp can be extended due to the decay of the electron radioactive material.

[0016] However, with the conventional electrode configuration, it is possible to extend the life of the hot cathode fluorescent lamp due to the decay of the electron-emitting substance, but it is not possible to extend the life due to the disconnection of the force electrode. This occurs because conventional electrodes have two roles: heating the electron emissive material and performing arc discharge.

[0017] The configuration of the electrode suitable for heating the electron-emitting substance has a heat resistance capable of withstanding a high temperature of about 2000 degrees or more, and has a large electric resistance for increasing the amount of heat generation. . In order to obtain a configuration having a large electric resistance, it is preferable to make the electrode as thin as possible. On the other hand, an electrode configuration suitable for performing arc discharge is resistant to electrical stress sputtering, that is, a configuration having a large volume or surface area.

[0018] For this reason, if the electrode is configured to be suitable for the role of heating the electron-emitting material, the electrode is not suitable for the role of performing arc discharge, and the configuration is suitable for the role of performing arc discharge. Then, it becomes the structure which is not suitable for the role which heats an electron radioactive substance. Conventional electrodes such as the filament electrode 103 in the hot-cathode fluorescent lamp 101 and the hollow electrode described in Patent Document 1 have an electrode configuration suitable for heating the electron-emitting material, and arc discharge. It is not suitable for the role to perform. As a result, when arc discharge is performed using a conventional electrode, the life of the hot cathode fluorescent lamp is shortened because the electrode is more likely to break due to electrical stress or sputtering.

[0019] Therefore, in order to suppress the disconnection of the electrode due to sputtering, an electrode portion including a cup-shaped electrode for protecting the filament electrode around the filament electrode is known. However, in the above electrode part, the force S that can suppress the disconnection of the filament electrode due to sputtering cannot be suppressed, and the disconnection due to electrical stress cannot be suppressed.

The present invention has been made in view of the above problems, and an object thereof is to provide an electrode section, a light source, an illumination device, and a liquid crystal display device that suppress the disconnection of the electrodes. [0021] In order to solve the above-mentioned problems, the electrode unit of the present invention is an electrode unit provided in a light source that emits light by heating an electron-emitting substance to emit thermoelectrons and performing arc discharge. It is characterized by having a first electrode for heating the radioactive material and a second electrode for arc discharge separately.

[0022] An electrode for heating the electron-emitting substance needs to be configured to be in a high temperature state in a short time with a large electric resistance. However, the electrode for performing arc discharge needs to have a structure resistant to electrical stress and sputtering, that is, a structure having a large volume or surface area.

[0023] Thus, according to the above configuration of the present invention, the electrode portion is divided into a first electrode for heating the electron-emitting material and a second electrode for performing arc discharge, thereby making the first electrode an electric resistance. The second electrode can have a large volume or surface area. That is, the second electrode does not need to have an increased electrical resistance in order to heat the electron-emitting material, and the degree of freedom in designing the second electrode is increased.

[0024] As a result, the first electrode can be rapidly brought to a high temperature state when the electron-emitting material is heated, and the second electrode can be disconnected due to electrical stress or sputtering even when arc discharge is performed. It is possible to suppress the power to do. Therefore, disconnection of the electrode can be suppressed, and an electrode part with a long life can be obtained.

Brief Description of Drawings

FIG. 1 is a diagram showing a schematic configuration of an embodiment of an electrode unit according to the present invention, (a) is a perspective view showing the electrode unit, and (b) is a diagram showing a heater wire connected to the electrode unit. Is a view from the side where

FIG. 2 is a diagram showing a configuration in which the insulating layer of the electrode part is replaced with a highly insulating layer, (a) is a cross-sectional view showing the electrode part, and (b) is a heater wire. It is the figure seen from the side where is provided.

FIG. 3 is a diagram showing a schematic configuration of a lighting device including the electrode unit.

FIG. 4 is a diagram showing a configuration of a main part of a drive circuit of the illumination device.

FIG. 5 is a diagram showing the relationship between the heater current, lamp voltage, and lamp current, and the preheating period, starting period, and steady period in lighting of the hot cathode fluorescent lamp. 6] A diagram showing a schematic configuration of a liquid crystal display device using the illumination device.

FIG. 7] A diagram showing a main part configuration of a conventional hot cathode fluorescent lamp.

FIG. 8] A diagram showing a configuration of a main part of a drive circuit of a lighting device provided with a conventional hot cathode fluorescent lamp.

FIG. 9] A diagram showing a main part configuration of a drive circuit configured to independently drive filament electrodes in a conventional hot cathode fluorescent lamp.

Explanation of symbols

1 Electrode section

2 Plate electrode (second electrode)

3 Insulating layer (insulating material)

4 Electrode wire

5 Filament (first electrode)

6 Heater wire

7 Electron radioactive material

8 High insulating layer (insulating material)

11 Lighting equipment

12 Hot cathode fluorescent lamp (light source)

13 Drive circuit (drive means)

14 Heater circuit (first electrode drive means)

15 Main discharge circuit (second electrode drive means)

16 Heater controller

17 Control unit

18 Switching circuit

19 Series LC resonant circuit

51 Liquid crystal display

52 Surface light source device

53 Optical sheet

54 LCD panel display BEST MODE FOR CARRYING OUT THE INVENTION

One embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

[0028] The electrode section of the present invention is provided with an electrode for heating the electron-emitting substance and an electrode for performing arc discharge separately. As a result, the electrode for performing the arc discharge has a high degree of design freedom and can be configured to prevent disconnection. As a result, the electrode portion of the present invention can suppress the occurrence of a spring break.

[Electrode part]

First, the electrode part 1 of this embodiment is demonstrated with reference to FIGS. FIG. 1 is a diagram showing a schematic configuration of an electrode unit 1 of the present embodiment, (a) is a perspective view of the electrode unit 1, and (b) is a side where the heater wire 6 is provided on the electrode unit 1. It is the figure seen from.

[0030] As shown in FIGS. 1A and 1B, the electrode section 1 of the present embodiment includes a plate-like electrode 2 (first

2 electrodes), an insulating layer 3 (insulating member), an electrode wire 4, a filament 5 (first electrode), and a heater wire 6. The electrode part 1 is preferably used for an electrode part of a hot cathode fluorescent lamp.

[0031] The plate electrode 2 is an electrode for performing arc discharge when the electrode unit 1 is applied to a hot cathode fluorescent lamp, for example. The plate-like electrode 2 is a circular plate having a predetermined thickness, and is made of Ni. In addition, the plate-like electrode 2 is coated with an electron-emitting substance 7 on one surface, and the electrode wire 4 for applying a lamp voltage from an external power source is connected to the plate-like electrode 2 on the other surface. Has been. On the surface of the plate-like electrode 2 to which the electrode line 4 is connected, an insulating layer 3 is formed on the other part excluding the electrode line 4. Further, the plate-like electrode 2 is connected to the filament 5 through the insulating layer 3, and the plate-like electrode 2 and the filament 5 are electrically insulated.

[0032] The surface of the plate-like electrode 2 on which the electron-emitting material 7 is applied may be a smooth surface or an uneven surface. The electron radioactive substance 7 may be mechanically applied or impregnated on the surface of the plate-like electrode 2 or applied by vapor deposition or etching. As the electron-emitting substance 7, an alkaline earth metal oxide such as Ba, Ca, Sr, an alkaline earth metal tungstate, or the like is preferably used.

[0033] The filament 5 is used to heat the electron-emitting material 7 applied to the plate-like electrode 2. It generates heat when current is supplied from an external power source via the heater wire 6. As shown in FIG. 1B, the filament 5 has a configuration in which a tungsten wire is wound in a coil shape, and is connected to the insulating layer 3. Note that the filament 5 is a force using a filament in FIG. 1 (b). The present invention is not limited to this, and the filament 5 has a large electric resistance and excellent heat resistance.

The heat radiated from the filament 5 is conducted to the plate electrode 2 through the insulating layer 3. When the plate-like electrode 2 is heated, the electron-emitting material 7 applied to the plate-like electrode 2 is also heated, and thermoelectrons are emitted from the electron-emitting material 7. Since the plate-like electrode 2 and the filament 5 are electrically insulated by the insulating layer 3, the lamp voltage is applied to the plate-like electrode 2 by the heater current supplied to the filament 5 via the heater wire 6. MARK That is, no current is supplied to the plate-like electrode 2 except that a lamp voltage is applied from the external power source via the electrode wire 4.

The shape of the plate-like electrode 2 is a force that is circular in FIGS. 1A and 1B. The present invention is not limited to this, and may be a polygon. That is, the plate-like electrode 2 only needs to have a configuration that can apply a large amount of the electron-emitting material 7 and can efficiently conduct the heat radiated from the filament 5 to the electron-emitting material 7. In addition, the plate-like electrode 2 of the present embodiment is composed of Ni. The present invention is not limited to this. For example, the plate-like electrode 2 is composed of a material having a high thermal conductivity such as alumina or molybdenum! /. If the plate-like electrode 2 is made of a material having a very high thermal conductivity, the plate-like electrode 2 does not have a force even if it is not plate-like. Similarly, as the material constituting the insulating layer 3, it is sufficient if it has insulating properties and thermal conductivity, for example, resin or ceramic is suitably used.

[0036] Further, what is formed between the plate-like electrode 2 and the filament 5 is not limited to the insulating layer 3, and as shown in FIGS. A highly insulating layer 8 made of a highly conductive material may be formed on the surface of the plate-like electrode 2 opposite to the surface on which the electron-emitting material 7 is applied. FIG. 2 is a view showing a configuration in which the insulating layer 3 of the electrode part 1 of the present embodiment is replaced with a highly insulating layer 8, and (a) is a cross-sectional view showing the electrode part 1, (b) Fig. 4 is a view of the electrode unit 1 as viewed from the side where the heater 6 wire is provided. [0037] As a material constituting the highly insulating layer 8, for example, aluminum oxide, magnesium oxide, or aluminum nitride is preferably used. By providing the highly insulating layer 8 between the plate electrode 2 and the filament 5, the heat radiated from the filament 5 is efficiently applied to the plate electrode 2 as shown by the arrow in FIG. Conducted.

[0038] In the electrode portion 1 of the present embodiment, the force in which the plate-like electrode 2 and the filament 5 are connected via the insulating layer 3 is not limited to this. That is, the plate electrode 2 and the filament 5 may be arranged separately without being connected, or may be directly connected without the insulating layer 3 interposed therebetween. In the case where the plate-like electrode 2 and the filament 5 are connected! /, Or! /, A member having a large surface area for applying the electron-emitting material 7 to the filament 5 may be connected. That is, the electrode part of the present invention only needs to have at least the plate-like electrode 2 for performing arc discharge and the filament 5 for heating the electron-emitting material 7.

[0039] As described above, the electrode unit 1 of the present embodiment is an electrode unit provided in a light source that emits light by heating the electron-emitting material 7 to emit thermoelectrons and performing arc discharge. The filament 5 for heating the electron-emitting material 7 and the plate electrode 2 for performing arc discharge are separately provided.

[0040] As described above, the electrode for heating the electron emissive substance 7 needs to have a configuration in which the electrical resistance is large and the temperature is raised in a short time. However, the electrode for performing the arc discharge needs to have a structure resistant to electrical stress, sputtering, etc., that is, a structure having a large volume or surface area.

[0041] Therefore, in the electrode part 1 of the present embodiment, the filament 5 is electrically separated by dividing it into a filament 5 for heating the electron-emitting substance 7 and a plate-like electrode 2 for performing arc discharge. In addition to a configuration having a large resistance, the plate-like electrode 2 can be configured to have a large volume or surface area. That is, the degree of freedom in designing the plate electrode 2 is very high.

[0042] As a result, the filament 5 can be rapidly brought to a high temperature state when the electron-emitting material 7 is heated, and the plate-like electrode 2 is disconnected due to electrical stress or sputtering even if arc discharge is performed. It is possible to suppress this. Therefore, the disconnection of the electrode can be suppressed, and the electrode part 1 having a long life can be obtained. [0043] [Lighting device]

Next, an illuminating device including a hot cathode fluorescent lamp including the electrode unit 1 according to the present embodiment will be described with reference to FIGS. 3 and 4. FIG. FIG. 3 is a diagram showing a schematic configuration of the illumination device 11 including the thermal cathode fluorescent lamp 12 including the electrode unit 1 of the present embodiment.

As shown in FIG. 3, the illumination device 11 includes a hot cathode fluorescent lamp 12 (light source) and a drive circuit 13 (drive means). The illumination device 11 is preferably used as a backlight for displaying an image on a liquid crystal display panel such as a liquid crystal TV, a liquid crystal display, or a liquid crystal monitor.

[0045] The hot cathode fluorescent lamp 12 is composed of a cylindrical glass tube and the electrode unit 1 of the present embodiment. The glass tube has an RGB inner wall surface coated with an RGB three-wavelength phosphor, and electrode portions 1 are provided on the inner sides of both ends. Further, the openings at both ends of the glass tube are closed by a base (not shown).

[0046] The drive circuit 13 is for controlling the drive of the electrode unit 1, and as shown in FIG. 3, a heater circuit 14 (first electrode drive means) for controlling the current supplied to the filament 5 And a main discharge circuit 15 (second electrode driving means) for controlling the voltage applied to the plate-like electrode 2 via the electrode wire 4. Here, specific configurations of the heater circuit 14 and the main discharge circuit 15 will be described with reference to FIG. FIG. 4 is a diagram illustrating a main configuration of the drive circuit 13.

As shown in FIG. 4, the heater circuit 14 includes a heater control unit 16 and a power source. The heater circuit 14 is connected to the filament 5 of the electrode unit 1 provided at both ends of the hot cathode fluorescent lamp 12. The heater control unit 16 adjusts the amount of heat radiated from the filament 5 by adjusting the amount of current supplied to the filament 5.

As shown in FIG. 4, the main discharge circuit 15 includes a control unit 17, a switching circuit 18, and a direct l] LC oscillation device 19. The control unit 17 switches the ON / OFF of the switching circuit 18 composed of two FETs, and controls the voltage applied to the direct IJLC oscillation device 19 to thereby control the plate-like electrode 2 of the electrode unit 1. The voltage applied to is controlled, and the drive of the hot cathode fluorescent lamp 12 is controlled.

[0049] The main discharge circuit 15 is not limited to the above configuration, and the voltage applied to the plate electrode 2 It is possible to control the driving of the hot cathode fluorescent lamp 12 by adjusting the power supply to the control unit 17 as long as the control of the driving of the hot cathode fluorescent lamp 12 can be controlled. Absent.

Here, the control of the electrode unit 1 of the present embodiment by the heater circuit 14 and the main discharge circuit 15 will be described with reference to FIG. FIG. 5 is a diagram showing the relationship between the heater current, the lamp voltage, and the lamp current, and the preheating period, starting period, and steady period in lighting of the hot cathode fluorescent lamp. First, the mechanism by which the hot cathode fluorescent lamp 12 emits light will be described below.

[0051] Prior to the lighting of the hot cathode fluorescent lamp 12, in the driving circuit 13 of the lighting device 11, the heater control unit 16 of the heater circuit 14 is provided at both ends of the hot cathode fluorescent lamp 12. A heater current is supplied from the power source to the filament 5 of the electrode portion 1 of the electrode. The filament 5 radiates heat, which is conducted to the plate electrode 2 through the insulating layer 3, and the plate electrode 2 is heated. The heat radiated from the filament 5 is conducted to the electron-emitting material 7 applied to the plate-like electrode 2, and the thermoelectrons are emitted from the electron-emitting material 7 into the glass tube of the hot cathode fluorescent lamp 12 ( Preheating period).

Next, in the drive circuit 13 of the illumination device 11, the control unit 17 of the main discharge circuit 15 turns on the switching circuit 18 and both the hot cathode fluorescent lamps 12 are connected via the direct IJLC oscillation device 19. A lamp voltage is applied to the plate-like electrode 2 through the electrode wire 4 provided at the end (starting period). Then, the hot electrons are attracted to the anode and discharge starts, a lamp current flows through the hot cathode fluorescent lamp 12, and ultraviolet rays are emitted when the hot electrons collide with mercury enclosed in the glass tube. Ultraviolet light excites the phosphor coated on the inner wall surface of the glass tube and emits visible light unique to the phosphor (stationary period).

[0053] Referring to FIG. 5, the heater current is supplied to the filament 5 at a constant current amount from the time when the preheating period starts until the steady period when the hot cathode fluorescent lamp 12 is turned on. The amount of current decreases. Further, the lamp voltage is applied to the plate electrode 2 via the electrode wire 4 from the start period in which arc discharge is performed to turn on the hot cathode fluorescent lamp 12 until the stationary period ends. The lamp current is generated in the hot cathode fluorescent lamp 12 from the steady period when the hot cathode fluorescent lamp 12 is lit until the end of the steady period. To be born. Note that the heater current is reduced in the supply amount in FIG. 5 after entering the steady period! /, But the supply may be stopped! /.

As described above, the illumination device 11 includes the heater circuit 14 that controls the current supplied to the filament 5 and the main discharge circuit 15 that controls the voltage applied to the plate electrode 2. After heating the electron-emitting material 7 with the filament 5, a sequence drive is possible in which an arc discharge is generated by the plate electrode 2. Therefore, the heater current value and the heater current supply time can be set freely, and the heater current can be easily varied even in the steady period.

[0055] The heater circuit 14 is connected to the filament 5 of the electrode portion 1, the main discharge circuit 15 is connected to the electrode wire 4 of the electrode portion 1, and the filament 5 and the plate-like electrode 2 An insulating layer 3 is provided between them to provide electrical insulation. Therefore, when current is supplied to the filament 5 by the heater circuit 14 in order to heat the electron-emitting substance 7, no current is supplied to the plate-like electrode 2, so that the plate-like electrodes at both ends of the hot cathode fluorescent lamp 12 are used. No glow current is generated in the hot cathode fluorescent lamp 12 where no lamp voltage is applied to 2. Therefore, since the time during which electrical stress, sputtering, etc. affect the electrode portion 1 of the present embodiment is shortened, the life of the hot cathode fluorescent lamp 12 can be extended.

[Liquid crystal display device]

Next, a liquid crystal display device using the illumination device 11 of the present embodiment will be described with reference to FIG. FIG. 6 is a diagram showing a schematic configuration of a liquid crystal display device 51 using the illumination device 11 of the present embodiment.

As shown in FIG. 6, the liquid crystal display device 51 is composed of a surface light source device 52 composed of a plurality of illumination devices 11, an optical sheet 53, and a liquid crystal display panel 54. In FIG. 6, for the sake of simplicity, the surface light source device 52 is described as including four illumination devices 11, but the number of illumination devices 11 is not limited thereto. With the above configuration, it is possible to obtain the liquid crystal display device 51 having a long-life backlight that is difficult to break.

In the liquid crystal display device 51, a plurality of illumination devices 11 are provided in parallel to the surface light source device 52, and an optical sheet 53 and a liquid crystal display panel 54 are stacked in this order on the upper surface of the surface light source device 52. . That is, the surface light source device 52 is a backlight in the liquid crystal display device 51. Is functioning as In the plurality of illumination devices 11 provided in the surface light source device 52, each plate-like electrode 2 and each filament 5 are connected to one drive circuit 13. That is, each plate-like electrode 2 of the plurality of lighting devices 11 is connected to one main discharge circuit 15 via each electrode wire 4, and each filament 5 is connected to one heater circuit 14 via each heater wire 6. Yes. Therefore, the drive circuit 13 controls the drive of the hot cathode fluorescent lamp 12 in all the illumination devices 11 provided in the surface light source device 52.

As the liquid crystal display panel 54, for example, an active matrix type color liquid crystal panel using TFT is preferably used. FIG. 6 shows a direct type backlight device, but the illumination device 11 of the present embodiment can also be applied to an edge type backlight device using a light guide plate and an optical sheet. .

[0060] Although not shown, the hot cathode fluorescent lamp 12 of the illumination device 11 in the liquid crystal display device 51 is held by a lamp holder. As the lamp holder, for example, a resin housing having a socket into which the electrode wire 4 and the heater wire 6 of the hot cathode fluorescent lamp 12 are inserted, a printed circuit board on which a socket is mounted, and the like are preferably used. The hot cathode fluorescent lamp 12 and the drive circuit 13 are connected via a lamp holder.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

[0062] In order to solve the above-mentioned problem, the electrode unit of the present invention is an electrode unit provided in a light source that emits light by heating an electron-emitting substance to emit thermoelectrons and performing arc discharge. It is characterized by having a first electrode for heating the radioactive material and a second electrode for arc discharge separately.

[0063] An electrode for heating the electron-emitting substance needs to be configured to be in a high temperature state in a short time with a large electric resistance. However, the electrode for performing arc discharge needs to have a structure resistant to electrical stress and sputtering, that is, a structure having a large volume or surface area.

[0064] Therefore, according to the above-described configuration of the present invention, the electrode portion is a second member for heating the electron-emitting material.

By dividing the first electrode into a second electrode for arc discharge, the first electrode The second electrode can have a large volume or surface area. That is, the second electrode does not need to have an increased electrical resistance in order to heat the electron-emitting material, and the degree of freedom in designing the second electrode is increased.

[0065] As a result, the first electrode can be rapidly brought to a high temperature state when the electron-emitting material is heated, and the second electrode can be disconnected due to electrical stress or sputtering even when arc discharge is performed. It is possible to suppress the power to do. Therefore, disconnection of the electrode can be suppressed, and an electrode part with a long life can be obtained.

[0066] Further, in the electrode portion of the present invention, an electron radioactive substance is applied to the second electrode, heat radiated from the first electrode is conducted to the second electrode, and the electron radioactive substance is heated. It may be configured.

[0067] With the above configuration, the electron-emitting material applied to the second electrode is heated by conduction of heat released from the first electrode to the second electrode. As described above, providing the first electrode for heating the electron-emitting substance and the second electrode for performing arc discharge separately increases the degree of freedom in designing the second electrode. Therefore, it is possible to increase the surface area of the second electrode. When the surface area of the second electrode is increased, a large amount of electron-emitting material can be applied. As a result, it is possible to lengthen the period until the electron radioactive substance is depleted, and it is possible to obtain an electrode part having a long lifetime.

[0068] In the electrode portion of the present invention, the first electrode and the second electrode may be electrically insulated.

[0069] When the electrode unit of the present invention is applied to, for example, a light source, conduction is made between the first electrode and the second electrode when a current is supplied to the first electrode to heat the electron-emitting substance. If there is, a voltage is applied to the second electrode of the light source and a glow current is generated.

When a glow current is generated in the light source, there is a high possibility that the second electrode of the electrode portion of the present invention will be disconnected due to electrical stress or sputtering, and the life will be shortened. Therefore, with the above-described configuration of the present invention, even if a current is supplied to the first electrode by electrically insulating the first electrode and the second electrode, the current flows to the second electrode. This can be suppressed. As a result, no gloss current is generated, and the life of the electrode part of the present invention can be extended. [0071] In the electrode portion of the present invention, an insulating member is provided between the first electrode and the second electrode, and the insulating member is made of aluminum oxide, magnesium oxide, or aluminum nitride. Motole.

[0072] When the electron-emitting substance is applied to the second electrode, it is necessary to conduct heat radiated from the first electrode to the second electrode. Therefore, the insulating member formed between the first electrode and the second electrode needs to have a configuration capable of conducting heat released from the first electrode to the second electrode. Therefore, with the above configuration of the present invention, the insulating member is made of aluminum oxide, magnesium oxide, or aluminum nitride, so that the heat radiated from the first electrode can be efficiently conducted to the second electrode, The electron-emitting material applied to the two electrodes can be heated quickly. Even when a current is supplied to the first electrode, it is possible to suppress the current from flowing to the second electrode with a higher probability.

[0073] A light source of the present invention is characterized by having the above-described electrode portion.

[0074] With the above configuration, it is possible to obtain a light source with a long lifetime that is difficult to break.

[0075] The illumination device of the present invention includes the above-described light source, and a driving unit that controls driving of the light source by controlling driving of the first electrode and the second electrode of the electrode unit. It is specially made.

[0076] With the above configuration, the driving unit supplies a current to the first electrode of the electrode part provided in the light source, and heats the electron-emitting material by radiating heat from the first electrode. Further, the driving means drives the light source by applying a voltage to the second electrode of the electrode part provided in the light source to cause arc discharge. As a result, it is possible to obtain a long-life lighting device that is difficult to break.

[0077] In the illumination device of the present invention, the driving unit includes a first electrode driving unit that controls a current supplied to the first electrode, and a second electrode that controls a voltage applied to the second electrode. It consists of electrode drive means.

In order to cause the light source to emit light, an electric current is supplied to the first electrode to heat the electron-emitting material, and then a voltage is applied to the second electrode to perform arc discharge. That is, it is necessary to drive the first electrode and the second electrode separately.

[0079] Thus, with the above configuration, the first electrode driving means for controlling the current supplied to the first electrode And the second electrode driving means for controlling the voltage applied to the second electrode, and after the electron radioactive material is heated by the first electrode, an arc discharge is caused by the second electrode! / Thus, sequence driving becomes possible.

[0080] In addition, when there is no conduction between the first electrode and the second electrode, when the current is supplied to the first electrode by the first electrode driving means in order to heat the electron-emitting material, the second electrode Since no current is supplied to the base, no glow current is generated. For this reason, since the time during which electrical stress, sputtering, and the like affect the electrode portion of the present invention is shortened, it is possible to use the force S for extending the life of the light source.

[0081] Further, in the lighting device of the present invention, after the first electrode driving means supplies a current to the first electrode for an arbitrary time, the second electrode driving means applies to the second electrode. The voltage is applied to cause arc discharge, and the first electrode driving means stops or reduces the supply of current to the first electrode.

[0082] With the above configuration, the first electrode and the second electrode are driven in turn using the first electrode driving means and the second electrode driving means, whereby the electron-emitting material is heated by the first electrode. After that, it becomes possible to perform sequence driving in which arc discharge is caused by the second electrode.

[0083] A liquid crystal display device of the present invention is characterized by including the above-described illumination device as a backlight.

[0084] With the above configuration, it is possible to obtain a liquid crystal display device having a long-life backlight that is difficult to break.

Industrial applicability

The present invention is suitably used as an electrode portion of a light source used as a backlight for displaying an image on a liquid crystal display panel such as a liquid crystal TV, a liquid crystal display, or a liquid crystal monitor.

Claims

The scope of the claims

[1] In an electrode part provided in a light source that emits light by heating an electron-emitting substance to emit thermoelectrons and performing arc discharge,

An electrode unit comprising a first electrode for heating the electron-emitting material and a second electrode for performing arc discharge separately.

[2] An electron radioactive substance is applied to the second electrode,

2. The electrode part according to claim 1, wherein heat radiated from the first electrode is conducted to the second electrode, and the electron-emitting substance is heated.

[3] The electrode part according to claim 1 or 2, wherein the first electrode and the second electrode are electrically insulated.

[4] The insulating member is provided between the first electrode and the second electrode, and the insulating member is made of aluminum oxide, magnesium oxide, or aluminum nitride. The electrode part as described in.

[5] A light source comprising the electrode part according to any one of [1] to [4].

[6] The light source according to claim 5,

An illuminating apparatus comprising: a driving unit that controls driving of the light source by controlling driving of the first electrode and the second electrode of the electrode unit.

[7] The driving means includes first electrode driving means for controlling a current supplied to the first electrode;

The lighting device according to claim 6, further comprising second electrode driving means for controlling a voltage applied to the second electrode.

[8] After the first electrode driving means supplies a current to the first electrode for an arbitrary time, the second electrode driving means applies a voltage to the second electrode to perform arc discharge, 8. The lighting device according to claim 7, wherein the first electrode driving means stops or reduces the supply of current to the first electrode.

[9] A liquid crystal display device comprising the illumination device according to any one of [6] to [8] as a backlight.