JP2010092798A - Cold cathode discharge lamp, lighting system, and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cold cathode discharge lamp improving dark start-up characteristic while reducing lamp voltage, and to provide a lighting system and an image display device improving start-up characteristics while reducing power consumption. <P>SOLUTION: The cold cathode discharge lamp 100 includes a light emitting tube 101, an electrode 102 provided in the light emitting tube 101, and an electron emission material layer 103 provided on a surface of the electrode 102. The electron emission material layer 103 includes a crack 105 at least in a part of its surface. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cold cathode discharge lamp, an illumination device, and an image display device.

FIG. 13 shows an enlarged cross-sectional view of a main part of a conventional cold cathode discharge lamp. A conventional cold cathode discharge lamp 1 (hereinafter referred to as “lamp 1”) is provided with one or more electrodes (internal electrodes) 3 inside a bulb 2 and also with electrodes (external electrodes) 4 on the outside. In the cold cathode discharge lamp 1 that is discharged between the internal electrode 3 and the external electrode 4, the internal electrode 3 includes a lanthanide (lanthanoid) rare earth as the electron emitting material 5 (for example, Patent Document 1) reference).
Japanese Patent Laid-Open No. 2-273452

  According to the study by the inventors, if the electrode of the cold cathode discharge lamp is provided with an electron-emitting material layer such as a lanthanoid rare earth, the lamp voltage is reduced by a lamp voltage lower than that of a lamp not provided with an electron-emitting material layer on the electrode. It was found that there is a possibility of contributing to energy saving.

  However, the provision of an electron emissive material layer such as a lanthanide-based rare earth on the electrode is still insufficient for the dark starting characteristics even though the lamp voltage can be lowered.

  In particular, since the cold cathode discharge lamp is often used as a backlight of an image display device such as a liquid crystal TV, a strict dark start characteristic that must be lit at 500 [ms] or less is required.

  Therefore, the cold cathode discharge lamp according to the present invention aims to improve the dark start characteristics while lowering the lamp voltage.

  Another object of the illumination device and the image display device according to the present invention is to improve starting characteristics while reducing power consumption.

  In order to solve the above problems, a cold cathode discharge lamp according to the present invention includes an arc tube, an electrode provided in the arc tube, and an electron-emitting material layer provided on the surface of the electrode. In the cold cathode discharge lamp, the electron-emitting material layer has a crack in at least a part of a surface thereof.

  In the cold cathode discharge lamp according to the present invention, it is preferable that the electrode has a bottomed cylindrical shape, and the electron-emitting material layer is provided on an inner surface of the electrode.

  In the cold cathode discharge lamp according to the present invention, it is preferable that the electron-emitting material layer is provided from the inner bottom surface of the electrode to a region of 1/3 or less of the length in the axial direction of the electrode.

  In the cold cathode discharge lamp according to the present invention, the crack is preferably formed at least in a portion corresponding to the inner bottom surface of the electrode in the electron-emitting material layer.

  In the cold cathode discharge lamp according to the present invention, the crack is formed at least in a portion corresponding to the inner side surface of the electrode in the electron-emitting material layer, and extends from the inner bottom surface of the electrode toward the opening. Is preferred.

  In the cold cathode discharge lamp according to the present invention, the electron-emitting material layer preferably contains a rare earth element.

  In the cold cathode discharge lamp according to the present invention, the rare earth element is preferably at least one of lanthanum (La) and yttrium (Y).

  Further, in the cold cathode discharge lamp according to the present invention, the electron-emitting material layer includes silicon (Si), aluminum (Al), zirconium (Zr), boron (B), zinc (Zn), bismuth (Bi), phosphorus It is preferable to include any one or more of (P) and tin (Sn).

  An illumination device according to the present invention includes a cold cathode discharge lamp.

  The image display device according to the present invention includes the illumination device.

  The cold cathode discharge lamp according to the present invention can improve the dark starting characteristics while lowering the lamp voltage.

  Moreover, the lighting device and the image display device according to the present invention can improve the starting characteristics while reducing power consumption.

(First embodiment)
The cross-sectional view including a cold cathode discharge lamp tube axis X ₁₀₀ according to a first embodiment of the present invention shown in FIG. A cold cathode discharge lamp 100 (hereinafter referred to as “lamp 100”) according to the first embodiment of the present invention is a cold cathode fluorescent lamp, and includes an arc tube 101 and an electrode 102 provided inside the arc tube 101. And an electron-emitting material layer 103 provided on the surface of the electrode.

  The arc tube 101 is made of borosilicate glass and is a straight tubular glass bulb, and a cross section cut perpendicularly to the tube axis is substantially circular. Specifically, for example, the outer diameter is 4 [mm], the inner diameter is 4 [mm], and the total length is 349 [mm]. The dimensions of the lamp 100 shown below are values corresponding to the dimensions of the arc tube 101 having an outer diameter of 4 [mm], an inner diameter of 3 [mm], and a total length of 349 [mm]. In the case of a cold cathode fluorescent lamp, the inner diameter is 1.4 [mm] to 7.0 [mm], and the wall thickness is within the range of 0.2 [mm] to 0.6 [mm]. The total length is preferably 1500 [mm] or less. These values are examples and are not limited to these.

  Inside the arc tube 101, for example, 3 [mg] mercury is sealed, and a rare gas such as argon or neon is sealed at a predetermined sealing pressure, for example, 40 [Torr]. As the rare gas, for example, a mixed gas of argon and neon having a molar ratio (Ar = 10 [%], Ne = 90 [%]) is used.

A phosphor layer 104 is formed on the inner surface of the arc tube 101. Further, between the inner surface of the arc tube 101 and the phosphor layer 104, for example, yttrium oxide (Y ₂ O ₃ ), silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), zinc oxide (ZnO), oxide A protective film (not shown) of a metal oxide such as titanium (TiO ₂ ) may be provided.

  The electrode 102 has a bottomed cylindrical shape, for example, an inner diameter of 2.3 [mm], an outer diameter of 2.7 [mm], a bottom thickness of 0.45 [mm], and a total length of 8.5 [mm]. mm] and made of nickel (Ni). The material of the electrode is not limited to nickel, and niobium (Nb), molybdenum (Mo), tantalum (Ta), tungsten (W), and the like can be used.

  The electrode 102 has an electron-emitting material layer 103 formed on the surface thereof. Specifically, the electron emissive material layer 103 is formed on the inner surface of the electrode 102. The electron emissive material layer 103 includes, for example, a rare earth element. This is because the cold cathode discharge lamp is effective for lowering the lamp voltage. Furthermore, the rare earth element is more preferably one or more of lanthanum (La) and yttrium (Y).

  An electron microscope (SEM) photograph of the inner bottom surface of the electrode 102 is shown in FIG. As shown in FIG. 2, the electron emissive material layer 103 has a crack 105 on at least a part of its surface. In the SEM photograph shown in FIG. 2, the electrode 102 is cut substantially perpendicularly to the longitudinal direction of the electrode at a position of 2 mm from the outer bottom surface toward the opening, and the inner bottom surface of the electrode from the electrode opening side. Was taken at a magnification of 3000 [times].

  The electron-emitting substance layer 103 can be formed by applying a material obtained by dissolving a rare earth element or the like, which is a material of the electron-emitting substance layer 103, in a solvent, drying the electrode, and then baking it. After the application, the electron-emitting material layer 103 in which cracks are formed after firing can be formed by drying. Drying is performed at 80 to 120 [° C.] for several minutes, for example.

  The electrode 102 is connected to one end surface of the lead wire 106 at a substantially central portion of the outer bottom surface.

  In the lead wire 106, for example, the outer bottom surface and one end surface of the electrode 102 are connected, and the inner lead wire 106a sealed to the glass bead 107 at a part of the side surface is connected to the other end surface and one end surface of the inner lead wire 106a. The external lead wire 106b is connected.

  The internal lead wire 106a has a wire diameter of 0.8 [mm] and is made of tungsten. The internal lead wire 106 a is preferably made of a material that matches the thermal expansion coefficient of the glass used as the material of the arc tube 101 and the glass bead 107. For example, when the arc tube 101 is Kovar glass, it is preferable to use an alloy of iron, nickel and cobalt (Kovar). Moreover, when the arc tube 101 is lead-free glass, it is preferable to use an alloy of iron and nickel.

  The external lead wire 106b has a wire diameter of 0.6 [mm] and is made of nickel. The material of the external lead wire is not limited to nickel, and may be, for example, an alloy of nickel and manganese or a dumet wire.

  The glass bead 107 has a substantially spherical shape, and seals the internal lead wire 106a along its substantially central axis, and is made of borosilicate glass. The glass beads 107 are preferably made of the same material as the arc tube 101 or a material having the same or similar thermal expansion coefficient as the arc tube 101 from the viewpoint of sealing properties.

(Experiment)
The inventors conducted two experiments to confirm that the lamp 100 can improve the dark starting characteristics while lowering the cathode fall voltage of the lamp as compared with the conventional cold cathode discharge lamp. Specifically, an experiment for measuring the cathode fall voltage of the lamp (Experiment 1) and an experiment for measuring the dark start time (Experiment 2). Hereinafter, each experiment will be described in detail.

(Experiment 1)
Three types of lamps were used in the experiment. First, a lamp having substantially the same configuration as that of the lamp 100 and having an electron-emitting material layer containing lanthanum (La) was taken as an example. Further, a lamp substantially the same as the lamp 100 was used as a comparative example except that the surface of the electron-emitting material layer was not cracked. Furthermore, in order to compare how much the lamp voltage has decreased, a lamp substantially the same as the embodiment was used as a reference example except that the surface of the electrode was not provided with an electron-emitting material layer. In addition, 3 [books] of Examples, Comparative Examples, and Reference Examples were produced and used for experiments. For reference, an SEM photograph of the electron-emitting material layer of the comparative example is shown in FIG. Note that the SEM shown in FIG. 3 is taken by the same method as the electron-emitting material layer of the lamp 100 described above. As shown in FIG. 3, the electron emissive material layer 108 of the comparative example has no cracks on its surface.

  In the experiment, first, the lamp voltage when lighting at a current value of 12 [mA] for each of the example, comparative example and reference example was measured by a cold cathode discharge tube characteristic test apparatus manufactured by NF Design Block Co., Ltd. Then, the average value of each was obtained. And the difference of the average value of the lamp voltage of a reference example, an Example, and a comparative example was calculated | required.

  The results of Experiment 1 are shown in Table 1.

  As shown in Table 1, it can be seen that both the example and the comparative example have almost the same effect of lowering the lamp voltage.

(Experiment 2)
Subsequently, the inventors conducted an experiment to check whether there was a difference in the dark start time between the example and the comparative example.

  In the experiment, 3 lamps of Example and Comparative Example having substantially the same configuration as Experiment 1 were used.

  In the experiment, the dark start characteristics were measured by starting and lighting the examples and comparative examples under dark conditions. The conditions for starting the lamp were 24 [h] dark at room temperature and then lighted in a dark state under 0.1 [Lux]. Then, the time from the start of applying a voltage to the lamp until the current flows through the lamp (starting delay time, ie, dark starting time) was measured with an oscilloscope. The experiment was performed 3 [units] for each of the example and the comparative example, and the average value of each dark start time was obtained.

  The results of Experiment 2 are shown in Table 2.

  As shown in Table 2, it can be seen that the dark start time is faster in the example than in the comparative example.

  The reason for this will be described in detail below in terms of the structure of the electron-emitting material layer. When the cold cathode discharge lamp is started, the rare gas ions in the arc tube are struck against the electrode surface, and the discharge is started by receiving energy and releasing electrons from the electrode. The conceptual diagram in the cross section of the electron-emitting substance layer of an Example is shown to Fig.4 (a), and the conceptual diagram in the cross section of the electron-emitting substance layer of a comparative example is shown in FIG.4 (b), respectively.

  As shown in FIG. 4A, in the case of the embodiment, a part of the rare gas ions 109 reaching the surface of the electron-emitting material layer 103 enters the crack 105 of the electron-emitting material layer 103 when the lamp is started. The rare gas ions 109 that have entered the crack 105 continue to repel in the crack 105, so that energy is given to the electron-emitting material layer 103 and activation of the electrons 110 can be activated whenever the repulsion occurs. Thereby, the embodiment can accelerate the dark start time.

  On the other hand, as shown in FIG. 4B, in the case of the comparative example, the rare gas ions 109 that reach the surface of the electron-emitting material layer 108 at the start of the lamp are merely struck against the surface of the electron-emitting material layer 108. There is no rebound within the crack as in the embodiment, and it is difficult to activate the emission of the electrons 110. As a result, the dark start-up time is delayed as compared with the embodiment.

  That is, from Experiments 1 and 2, it was confirmed that the lamp 100 can improve the dark starting characteristics while lowering the cathode fall voltage of the lamp as compared with the conventional cold cathode discharge lamp.

  As described above, according to the configuration of the cold cathode discharge lamp 100 according to the first embodiment of the present invention, it is possible to improve the dark start characteristics while lowering the cathode fall voltage of the lamp.

  In addition, it is preferable that an electron emissive substance layer exists from the inner bottom face of the electrode to a region of 1/3 or less of the length in the axial direction of the electrode. In this case, it is possible to prevent the electron-emitting material layer from being scattered on the wall surface of the arc tube and the phosphor layer as the discharge time elapses. Furthermore, it is more preferable that the electron-emitting material layer exists from the inner bottom surface of the electrode to a region of ¼ or less of the length in the axial direction of the electrode.

  Furthermore, as shown in FIG. 5, the crack 105 is preferably formed at least in a portion corresponding to the inner side surface of the electrode 102 in the electron emissive material layer 103 and extends from the inner bottom surface of the electrode 102 toward the opening. In this case, when the electrode has a bottomed cylindrical shape, the rare gas ions easily enter the crack when starting the lamp, and the dark starting characteristics can be improved.

  The width of the crack 105 is preferably in the range of 0.1 [μm] to 1 [μm]. In this case, when the lamp is started, rare gas ions can easily enter the crack, and the electron-emitting material layer can be made difficult to fall off. More preferably, it is in the range of 0.3 [μm] or more and 0.7 [μm] or less.

  Moreover, although the crack 105 may be formed intermittently, it is more preferable that it is formed continuously. In this case, the noble gas ions can easily enter the crack when starting the lamp, and the dark starting characteristics can be further improved.

(Second Embodiment)
FIG. 6 shows a cross-sectional view including the tube axis of the cold cathode discharge lamp according to the second embodiment of the present invention. A discharge lamp 200 according to the second embodiment of the present invention (hereinafter simply referred to as “lamp 200”) is an internal / external electrode type cold cathode fluorescent lamp.

  The lamp 200 has an external electrode 201 on the outer surface of one end thereof, and has substantially the same configuration as the cold cathode discharge lamp 100 according to the first embodiment of the present invention except for the configuration associated therewith. Therefore, the external electrode 201 and the configuration accompanying it will be described in detail, and the other points will be omitted.

  The external electrode 201 is made of, for example, solder and is formed so as to cover the outer peripheral surface of one end of the arc tube 101.

  The external electrode 201 may be formed by applying silver paste to the entire circumference of the electrode forming portion of the arc tube 101, or a metal cap may be placed on the end of the arc tube 101. Further, an aluminum metal foil may be attached so as to cover the entire outer peripheral surface of the arc tube 101 with a conductive adhesive (not shown) in which metal powder is mixed with silicone resin. . In addition, in a conductive adhesive, you may use a fluororesin, a polyimide resin, or an epoxy resin instead of a silicone resin.

Although not shown in FIG. 6, a protective film of, for example, yttrium oxide (Y ₂ O ₃ ) may be provided on the inner surface of the arc tube 101 where the external electrode 201 is formed. By providing the protective film, it is possible to prevent glass scraping and pinholes caused by mercury ions colliding with the portion of the arc tube 101.

The protective film may be made of metal oxide such as silica (SiO ₂ ), alumina (Al ₂ O ₃ ), zinc oxide (ZnO), titania (TiO ₂ ), for example, instead of yttrium oxide. In particular, when the protective film is formed of yttrium oxide or silica, mercury hardly adheres to the protective film, and mercury consumption is low.

  However, the protective film is not an essential component in the present invention and may not be formed at all, or may be formed over the entire inner surface of the arc tube 101.

  As described above, according to the configuration of the cold cathode discharge lamp 200 according to the second embodiment of the present invention, the dark start-up characteristics can be improved while lowering the cathode fall voltage of the lamp.

(Third embodiment)
FIG. 7 shows a cross-sectional view including the tube axis of the lighting apparatus according to the third embodiment of the present invention. An illuminating device 300 (hereinafter simply referred to as “illuminating device 300”) according to a sixth embodiment of the present invention is a direct-type backlight unit, and includes a rectangular parallelepiped case 301 having an opening on one surface, and the case. A plurality of lamps 100 housed in the body 301, a pair of sockets 302 for electrically connecting the lamps 100 to a lighting circuit (not shown), and optical sheets 303 covering the opening of the housing 301 And. The lamp 100 is the discharge lamp 100 according to the first embodiment of the present invention.

  The housing 301 is made of, for example, polyethylene terephthalate (PET) resin, and a reflective surface 304 is formed by depositing a metal such as silver on the inner surface thereof. In addition, as a material of the housing | casing 301, you may comprise by metal materials, such as materials other than resin, for example, aluminum, a cold rolled material (for example, SPCC). In addition to the metal vapor-deposited film, for example, a reflective sheet 304 having a reflectivity enhanced by adding calcium carbonate, titanium dioxide or the like to polyethylene terephthalate (PET) resin is used as the inner reflective surface 304. May be.

  Inside the casing 301, a socket 302, an insulator 305, and a cover 306 are arranged. Specifically, the sockets 302 are provided at predetermined intervals in the lateral direction (vertical direction) of the housing 301 corresponding to the arrangement of the lamps 100. The socket 302 is obtained by processing a plate made of, for example, stainless steel or phosphor bronze, and has a fitting portion 302a into which the lead wire 106 is fitted. Then, the lead wire 106 is elastically deformed so as to expand the fitting portion 302a. As a result, the lead wire 103 fitted into the fitting portion 302a is pressed by the restoring force of the fitting portion 302a and is difficult to come off. Accordingly, the lead wire 106 can be easily fitted into the fitting portion 302a, but can be made difficult to come off.

  The socket 302 is covered with an insulator 305 so as not to short-circuit between adjacent sockets 302. The insulator 305 is made of, for example, polyethylene terephthalate (PET) resin. Note that the insulator 305 is not limited to the above structure. Since the socket 302 is in the vicinity of the internal electrode that becomes relatively hot during operation of the lamp 100, the insulator 305 is preferably made of a heat resistant material. As a material for the heat-resistant insulator 305, for example, polycarbonate (PC) resin, silicon rubber, or the like can be used.

  A lamp holder 307 may be provided inside the housing 301 at a place as necessary. The lamp holder 307 that fixes the position of the lamp 100 inside the housing 301 is, for example, polycarbonate (PC) resin, and has a shape that conforms to the outer surface shape of the lamp 100. “A place where necessary” means that the deflection of the lamp 100 is caused when the lamp 100 has a long length exceeding, for example, 600 [mm], as in the vicinity of the central portion of the lamp 100 in the longitudinal direction. It is a place necessary to eliminate.

  The cover 306 divides the socket 302 from the space inside the housing 301. The cover 306 is made of, for example, polycarbonate (PC) resin, keeps the periphery of the socket 302 warm, and highly reflects at least the surface on the housing 301 side. By reducing the brightness, a decrease in luminance at the end of the lamp 100 can be reduced.

  The opening of the housing 301 is covered with a translucent optical sheet 303 and is sealed so that foreign matters such as dust and dust do not enter inside. The optical sheet 303 is formed by laminating a diffusion plate 308, a diffusion sheet 309, and a lens sheet 310.

  The diffusion plate 308 is a plate-like body made of, for example, polymethyl methacrylate (PMMA) resin, and is disposed so as to close the opening of the housing 301. The diffusion sheet 309 is made of, for example, a polyester resin. The lens sheet 310 is, for example, a laminate of an acrylic resin and a polyester resin. These optical sheets 303 are arranged so as to be sequentially superimposed on the diffusion plate 308.

  As described above, according to the configuration of the lighting apparatus 300 according to the third embodiment of the present invention, it is possible to improve the starting characteristics while reducing power consumption.

(Fourth embodiment)
FIG. 8 shows a partially cutaway perspective view of a lighting apparatus according to the fourth embodiment of the present invention. An illuminating device 400 (hereinafter referred to as “illuminating device 400”) according to the fourth embodiment of the present invention is an edge light type backlight unit, and includes a reflector 401, a lamp 100, a socket (not shown), and a light guide plate. 402, a diffusion sheet 403, and a prism sheet 404.

  The reflection plate 401 is disposed so as to surround the periphery of the light guide plate 402 except for the liquid crystal panel side (arrow Q), and the side surface covering the bottom surface portion 401b covering the bottom surface and the side surface excluding the side where the lamp 100 is disposed. Part 401a and a curved lamp side surface part 401c covering the periphery of the lamp 100, and reflects light emitted from the lamp 100 from the light guide plate 402 to the liquid crystal panel (not shown) side (arrow Q). Let Further, the reflection plate 401 is made of, for example, a film of PET deposited with silver or a metal foil such as aluminum laminated.

  The socket has substantially the same configuration as the connection terminal used in the lighting device 300 according to the third embodiment of the present invention. In FIG. 8, the end of the lamp 100 is omitted for convenience of illustration.

  The light guide plate 402 is for guiding the light reflected by the reflection plate to the liquid crystal panel side. The light guide plate 402 is made of, for example, translucent plastic and is stacked on the reflection plate 401 provided on the bottom surface of the lighting device 400. Has been. As a material, polycarbonate (PC) resin or cycloolefin-based resin (COP) can be applied.

  The diffusion sheet 403 is for expanding the visual field, and is made of a film having a diffusion transmission function made of, for example, polyethylene terephthalate resin or polyester resin, and is stacked on the light guide plate 402.

  The prism sheet 404 is for improving luminance, and is made of, for example, a sheet obtained by bonding an acrylic resin and a polyester resin, and is laminated on the diffusion sheet 403. Note that a diffusion plate (not shown) may be further stacked on the prism sheet 404.

  In the case of this embodiment, a reflective sheet (not shown) is provided on the outer surface of the arc tube 101 except for a part in the circumferential direction of the lamp 100 (on the light guide plate 402 side when inserted into the lighting device 400). An aperture-type lamp may be used.

  As described above, according to the configuration of the illumination device 400 according to the fourth embodiment of the present invention, it is possible to improve the starting characteristics while reducing power consumption.

(Fifth embodiment)
FIG. 9 shows an outline of an image display apparatus according to the fifth embodiment of the present invention. As shown in FIG. 9, the image display device 500 is, for example, a 32 [inch] liquid crystal television (liquid crystal display device), a liquid crystal screen unit 501 including a liquid crystal panel and the like, and an illumination device 300 according to the third embodiment of the present invention. And a lighting circuit 502.

  The liquid crystal screen unit 501 is a publicly known one and includes a liquid crystal panel (color filter substrate, liquid crystal, TFT substrate, etc.) (not shown), a drive module, etc. (not shown), and is based on an image signal from the outside. To form a color image.

  The lighting circuit 502 lights the lamp 100 inside the lighting device 300. The lamp 100 is operated at a lighting frequency of 40 [kHz] to 100 [kHz] and a lamp current of 3.0 [mA] to 25 [mA].

  In addition, although FIG. 9 demonstrated the case where the discharge lamp 100 which concerns on 1st Embodiment was inserted in the illuminating device 300 which concerns on the 3rd Embodiment of this invention as a light source device of the image display apparatus 500, it is not restricted to this. It is also possible to apply the cold cathode discharge lamp 200 according to the second embodiment of the present invention. Moreover, the illuminating device 400 which concerns on the 4th Embodiment of this invention can also be used also about an illuminating device.

  As described above, according to the configuration of the image display apparatus 500 according to the fifth embodiment of the present invention, it is possible to improve the starting characteristics while reducing power consumption.

(Modification)
As described above, the present invention has been described based on the specific examples shown in the above embodiments. However, the content of the present invention is not limited to the specific examples shown in the respective embodiments. Variations can be used.

1. Modification of cold cathode discharge lamp (1) Modification 1
FIG. 10A shows a front view of Modification 1 of the cold cathode discharge lamp according to the first embodiment of the present invention, and FIG. 10B shows an enlarged cross-sectional view including the tube axis. The cold cathode discharge lamp 111 (hereinafter referred to as “lamp 111”) according to the first embodiment of the present invention has substantially the same configuration as the lamp 100 except that the base 112 is provided. Therefore, the electrode will be described in detail below.

  The base 112 is electrically and mechanically connected to the lead wire 106. Specifically, the base includes a body part 112 a that covers the end of the arc tube 101, and an extension part 112 b that extends from one end of the body part 112 a and is electrically and mechanically connected to the lead wire 106. Has been. Such a lamp 111 can be electrically and mechanically connected by simply inserting the base 112 into a fuse socket (not shown) or the like when incorporated in the lighting device.

  A holding portion 112c for holding the arc tube 101 is provided on the side surface of the body portion 112a. The holding part 112c is formed, for example, by cutting out a part of the side surface of the body part 112a and bending it toward the arc tube 101 side. The tip 112d of the holding portion 112c is bent to the opposite side of the arc tube 101 so as not to damage the arc tube 101. In addition, it is preferable that 3 [locations] or more of the holding portions 112c are provided at substantially equal intervals in the circumferential direction of the body portion 112a. This is because the arc tube 101 can be held more stably. Furthermore, it is preferable that the contact portion between the holding portion 112 c and the arc tube 101 is in a portion facing the electrode 102. In this case, heat dissipation generated near the electrode 102 can be promoted through the holding portion 112c, and the electron-emitting material layer 103 can be prevented from scattering on the inner surface of the arc tube 101 and the phosphor layer 104. Can do.

(2) Modification 2
FIG. 11A shows an enlarged cross-sectional view of a main part of Modification 2 of the cold cathode discharge lamp according to the first embodiment of the present invention. A cold cathode discharge lamp 113 (hereinafter referred to as “lamp 113”) according to the first embodiment of the present invention has substantially the same configuration as the lamp 100 except that the structure of the electrode 114 is different. Therefore, the electrode 114 will be described in detail below.

  The electrode 114 has a bottomed cylindrical shape, and an end portion 114a on the opening side thereof extends outward in the radial direction. In this case, a gap between the outer side surface of the electrode 114 and the inner surface of the arc tube 101 can be reduced, and discharge can be prevented from flowing around the outer side surface of the electrode 114 and the outer side surface of the electrode 114 being sputtered. can do.

  The electron emissive material layer 103 is formed on the inner surface of the electrode 114 except at least the end portion 114a on the opening side that spreads outward in the radial direction of the electrode 114. Thereby, it is possible to prevent the electron-emitting material layer 103 from being scattered on the inner surface of the arc tube 101 and the phosphor layer 104.

(3) Modification 3
FIG. 11B is an enlarged cross-sectional view of the main part of Modification 3 of the cold cathode discharge lamp according to the first embodiment of the present invention. The cold cathode discharge lamp 115 (hereinafter referred to as “lamp 115”) according to the first embodiment of the present invention has substantially the same configuration as the lamp 100 except that the structure of the electrode 116 is different. Therefore, the electrode 116 will be described in detail below.

  The electrode 116 has a bottomed cylindrical shape, and an end 116a on the opening side thereof is narrowed inward in the radial direction. The electron emissive material layer 103 is formed on the inner surface of the electrode 116 except at least the end portion 116a on the opening side that narrows inward in the radial direction of the electrode 116. As a result, the electron emitting material layer 103 is prevented from being sputtered by the end portion 116 a of the electrode 116, and even if the electron emitting material layer 103 is sputtered, the scattered electron emitting material layer 103 remains at the end of the electrode 116. By being blocked by the portion 116a, scattering to the inner surface of the arc tube 101 and the phosphor layer 104 can be prevented.

(4) Modification 4
The principal part expanded sectional view of the modification 4 of the cold cathode discharge lamp which concerns on the 1st Embodiment of this invention is shown to Fig.12 (a). The cold cathode discharge lamp 117 (hereinafter referred to as “lamp 117”) according to the first embodiment of the present invention has substantially the same configuration as the lamp 100 except that the structure of the electron-emitting material layer 118 is different. Have Therefore, the electron emissive material layer 118 will be described in detail below.

  The electron emissive material layer 118 is formed on the inner bottom surface of the electrode 102. Thereby, even if the electron-emitting material layer 118 is sputtered, it can be prevented from being scattered on the inner surface of the arc tube 101 and the phosphor layer 104 by being scattered on the inner side surface of the electrode 102.

(5) Modification 5
The principal part expanded sectional view of the modification 5 of the cold cathode discharge lamp which concerns on the 1st Embodiment of this invention is shown in FIG.12 (b). The cold cathode discharge lamp 119 (hereinafter referred to as “lamp 119”) according to the first embodiment of the present invention has substantially the same configuration as the lamp 100 except that the structure of the electron-emitting material layer 120 is different. Have Therefore, the electron emissive material layer 120 will be described in detail below.

  The electron emissive material layer 120 is formed on the inner surface of the electrode 102 and decreases in thickness from the inner bottom surface of the electrode 102 toward the opening. In this case, even if the electron emissive material layer 120 near the opening of the electrode 102 is sputtered, since the electron emissive material layer 120 sputtered from the inner bottom portion of the electrode 102 is replenished, the effect of lowering the lamp voltage is maintained. Can be made.

(6) Other Modifications Note that the electron-emitting material layer 120 may contain a cesium (Cs) compound. In this case, the dark start characteristics of the lamp can be further improved. In addition to the electron radioactive material layer, a cesium compound may be attached to the inner and outer surfaces of the electrode.

  As the cesium compound, for example, it is preferable to use at least one of cesium sulfate, cesium aluminate, cesium niobate, cesium tungstate, cesium molybdate, and cesium chloride.

2. Regarding the arc tube (1) About UV absorption Absorption of 254 [nm] or 313 [nm] UV can be achieved by doping a glass, which is the material of the arc tube, with a transition metal oxide in a predetermined amount. . Specifically, for example, in the case of titanium oxide (TiO ₂ ), the composition ratio of 0.05 [mol%] or more is doped to absorb ultraviolet rays of 254 [nm], and the composition ratio is 2 [mol%] or more. Thus, it is possible to absorb ultraviolet rays of 313 [nm]. However, when titanium oxide is doped more than the composition ratio of 5.0 [mol%], the glass is devitrified, so the composition ratio is 0.05 [mol%] or more and 5.0 [mol%] or less. It is preferable to dope in the range.

In the case of cerium oxide (CeO ₂ ), 254 [nm] ultraviolet rays can be absorbed by doping at a composition ratio of 0.05 [mol%] or more. However, when cerium oxide is doped more than 0.5 [mol%], the glass is colored, so cerium oxide has a composition ratio of 0.05 [mol%] to 0.5 [mol%]. It is preferable to dope in the following range. In addition, since coloring of glass by cerium oxide can be suppressed by doping tin oxide (SnO) in addition to cerium oxide, cerium oxide can be doped to a composition ratio of 5.0 [mol%] or less. . In this case, if cerium oxide is doped with a composition ratio of 0.5 [mol%] or more, ultraviolet rays of 313 [nm] can be absorbed. However, even in this case, when the composition ratio of cerium oxide is more than 5.0 [mol%], the glass is devitrified.

  In the case of zinc oxide (ZnO), ultraviolet rays having a wavelength of 254 [nm] can be absorbed by doping with a composition ratio of 2.0 [mol%] or more. However, when zinc oxide is doped more than 20 [mol%], the glass may be devitrified, so zinc oxide is in the range of 2.0 [mol%] to 20 [mol%]. It is preferable to dope.

Further, in the case of iron oxide (Fe ₂ O ₃ ), 254 [nm] ultraviolet rays can be absorbed by doping at a composition ratio of 0.01 [mol%] or more. However, when iron oxide is doped more than the composition ratio of 2.0 [mol%], the glass is colored, so the iron oxide is contained in the composition ratio of 0.01 [mol%] to 2.0 [mol%]. It is preferable to dope in the following range.

(2) Infrared transmission coefficient The infrared transmission coefficient indicating the water content in the glass is adjusted to be in the range of 0.3 to 1.2, particularly 0.4 to 0.8. Is preferred. When the infrared transmittance coefficient is 1.2 or less, it becomes easy to obtain a low dielectric loss tangent applicable to a high voltage application lamp such as an external electrode discharge lamp (EEFL) or a long cold cathode discharge lamp, and 0.8 or less. If so, the dielectric loss tangent becomes sufficiently small and can be applied to a high voltage application lamp.

  The infrared transmittance coefficient (X) can be expressed by the following formula.

[Expression 1] X = (log (a / b)) / t
a: Transmittance [%] of a minimum point in the vicinity of 3840 [cm ⁻¹ ]
b: Transmittance [%] of a minimum point in the vicinity of 3560 [cm ⁻¹ ].
t: Glass thickness (3) Shape of arc tube The shape of the arc tube is not limited to a straight tube shape, and may be, for example, an L shape, a U shape, a U shape, a spiral shape, or the like. . Further, the cross section cut perpendicularly to the tube axis is not limited to a substantially circular shape, and may be, for example, a flat shape such as a track shape or a rounded corner shape, or an elliptical shape.

3. Regarding phosphors in the phosphor layer (1) About ultraviolet absorption For example, in recent years, with the increase in size of liquid crystal color televisions, polycarbonate with good dimensional stability has been used for the diffusion plate that closes the opening of the backlight unit. ing. This polycarbonate is easily deteriorated by ultraviolet rays having a wavelength of 313 [nm] emitted from mercury. In such a case, a phosphor that absorbs ultraviolet light having a wavelength of 313 [nm] may be used. The following phosphors absorb 313 [nm] ultraviolet rays.

(A) barium strontium magnesium active aluminate with blue, europium manganese co _{[Ba 1-xy Sr x Eu} y Mg 1-z Mn z Al 10 O 17] or _{[Ba 1-xy Sr x Eu} y Mg 2 _-z Mn _z Al ₁₆ O ₂₇ ]
Here, x, y, and z are preferably numbers satisfying the conditions of 0 ≦ x ≦ 0.4, 0.07 ≦ y ≦ 0.25, and 0 ≦ z <0.1, respectively.

Examples of such phosphors include europium activated barium magnesium aluminate [BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ], [BaMgAl ₁₀ O ₁₇ : Eu ²⁺ ] (abbreviation: BAM-B), Europium activated barium aluminate / strontium / magnesium [(Ba, Sr) Mg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ], [(Ba, Sr) MgAl ₁₀ O ₁₇ : Eu ²⁺ ] (abbreviation: SBAM-B) Etc.

(B) Green • Manganese inactive magnesium gallate [MgGa ₂ O ₄ : Mn ²⁺ ] (abbreviation: MGM)
Manganese activated cerium aluminate, magnesium, zinc [Ce (Mg, Zn) Al ₁₁ O ₁₉ : Mn ²⁺ ] (abbreviation: CMZ)
· Active aluminate, cerium-magnesium with terbium ^{_{[CeMgAl 11 O 19: Tb 3+}} ] ( abbreviation: CAT)
• Europium • Manganese co-activated barium aluminate • Strontium • Magnesium [Ba _{1 -xy} Sr _x Eu _y Mg _{1 -z} Mn _z Al ₁₀ O ₁₇ ] or [Ba _{1 -xy} Sr _x Eu _y Mg _{2 -z} Mn _z Al ₁₆ O ₂₇ ]
Here, x, y, z are numbers satisfying the conditions of 0 ≦ x ≦ 0.4, 0.07 ≦ y ≦ 0.25, and 0.1 ≦ z ≦ 0.6, respectively, and z is 0.4 It is preferable that ≦ x ≦ 0.5.

Examples of such phosphors include europium / manganese co-activated barium aluminate / magnesium [BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ ], [BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ^{2]. +} ] (Abbreviation: BAM-G), europium / manganese co-activated barium aluminate / strontium / magnesium [(Ba, Sr) Mg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ ], [(Ba, Sr) MgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ²⁺ ] (abbreviation: SBAM-G).

(C) Red • Europium activated phosphorus • Yttrium vanadate [Y (P, V) O ₄ : Eu ³⁺ ] (abbreviation: YPV)
Europium activated yttrium vanadate [YVO ₄ : Eu ³⁺ ] (abbreviation: YVO)
・ Europium-activated yttrium oxysulfide [Y ₂ O ₂ S: Eu ³⁺ ] (abbreviation: YOS)
Manganese-activated magnesium fluoride germanate [3.5MgO.0.5MgF ₂ .GeO ₂ : Mn ⁴⁺ ] (abbreviation: MFG)
Dysprosium-activated yttrium vanadate [YVO ₄ : Dy ³⁺ ] (red and green two-component phosphor, abbreviation: YDS)
In addition, you may mix and use the fluorescent substance of a different compound with respect to one type of luminescent color. For example, only BAM-B (absorbs 313 [nm]) in blue, LAP (does not absorb 313 [nm]) in green, BAM-G (absorbs 313 [nm]) in green, and YOX in red Alternatively, a phosphor of YVO (absorbs 313 [nm]) may be used. In such a case, as described above, the phosphor that absorbs the wavelength 313 [nm] is adjusted so that the total weight composition ratio is larger than 50%, so that the ultraviolet rays almost leak out of the glass bulb. Can be prevented. Therefore, when the phosphor layer 105 includes a phosphor that absorbs ultraviolet rays of 313 [nm], deterioration due to ultraviolet rays such as a diffusion plate made of polycarbonate (PC) that closes the opening of the backlight unit is suppressed, The characteristics as a backlight unit can be maintained for a long time.

  Here, “absorbing ultraviolet rays of 313 [nm]” means an excitation wavelength spectrum near 254 [nm] (excitation wavelength spectrum means excitation light emission while changing the wavelength of the phosphor, and the excitation wavelength and emission intensity are changed. The intensity of the excitation wavelength spectrum at 313 [nm] is defined as 80 [%] or more. That is, the phosphor that absorbs ultraviolet rays of 313 [nm] is a phosphor that can absorb ultraviolet rays of 313 [nm] and convert it into visible light.

(2) High color reproduction Liquid crystal display devices typified by liquid crystal color televisions have been used as a light source for a backlight unit of the liquid crystal display device in accordance with the recent high color reproduction that has been made as part of higher image quality. In a cathode discharge lamp, there is a demand for an expansion of a reproducible chromaticity range.

  In response to such a request, for example, by using the following phosphor, the chromaticity range can be expanded as compared with the case of using the phosphor in the embodiment. Specifically, in the CIE 1931 chromaticity diagram, the chromaticity coordinate value of the phosphor for high color reproduction includes a triangle formed by connecting the chromaticity coordinate values of the three phosphors used in the embodiment. Located at the coordinates that expand the reproduction range.

(A) Blue • Europium-activated strontium chloroapatite [Sr ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ ] (abbreviation: SCA), chromaticity coordinates: x = 0.151, y = 0.065
In addition to the above, europium activated strontium, calcium, barium, chloroapatite [(Sr, Ca, Ba) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ ] (abbreviation: SBCA) can also be used, and the wavelength 313 (nm) SBAM-B, which can absorb ultraviolet rays), can also be used for high color reproduction.

(B) Green BAM-G, chromaticity coordinates: x = 0.139, y = 0.574
CMZ, chromaticity coordinates: x = 0.164, y = 0.722
CAT, chromaticity coordinates: x = 0.267, y = 0.663
As described above, these can also absorb ultraviolet rays having a wavelength of 313 [nm], and in addition to the three phosphor particles described here, MGM can also be used for high color reproduction.

(C) Red • YOS, chromaticity coordinates: x = 0.651, y = 0.344
YPV, chromaticity coordinates: x = 0.658, y = 0.333
MFG, chromaticity coordinates: x = 0.711, y = 0.287
As described above, these can also absorb ultraviolet rays having a wavelength of 313 [nm], and besides the three phosphor particles described here, YVO and YDS can also be used for high color reproduction.

  In addition, the chromaticity coordinate values shown above are representative values measured only with each phosphor powder, and due to the measurement method (measurement principle), etc., the chromaticity coordinates indicated by each phosphor powder The value may be slightly different from the value listed above. For reference, the chromaticity coordinate values of the phosphor powders of the first embodiment are YOX (x = 0.644, y = 0.353), LAP (x = 0.351, y = 0.585). , BAM-B (x = 0.148, y = 0,056).

  Furthermore, the phosphor used for emitting each color of red, green, and blue is not limited to one type for each wavelength, and a plurality of types may be used in combination.

  Here, the case where a phosphor layer is formed using the above-described phosphor particles for high color reproduction will be described. In this evaluation, there are three evaluations in the case of using a phosphor for high color reproduction based on the area of NTSC triangle (NTSC triangle) connecting the chromaticity coordinate values of the three primary colors of the NTSC standard in the CIE1931 chromaticity diagram. It is performed by a ratio of the area of a triangle formed by connecting chromaticity coordinate values (hereinafter referred to as NTSC ratio).

  For example, when BAM-B is used as blue, BAM-G as green, and YVO as red (Example 1), the NTSC ratio is 92%, and SCA is used as blue, BAM-G as green, and YVO as red. (Example 2) When NTSC ratio is 100%, SCA is used as blue, BAM-G is used as green, and YOX is used as red (Example 3), NTSC ratio is 95%. The luminance can be improved by 10 [%] as compared with the above.

  Note that the chromaticity coordinate values used for the evaluation here are measured in the state of a liquid crystal display device in which a lamp or the like is incorporated, so that the color reproduction range is around the above value depending on the combination with the color filter. there is a possibility.

4). Regarding types of discharge lamps In each of the above embodiments, the cold cathode discharge lamp has been described centering on a cold cathode fluorescent lamp. However, the present invention is not limited to this, and an ultraviolet lamp in which a phosphor layer is not formed on the inner surface of the arc tube. It may be.

  The present invention can be widely applied to cold cathode discharge lamps, illumination devices, and image display devices.

Sectional drawing including the tube axis | shaft of the cold cathode discharge lamp which concerns on the 1st Embodiment of this invention Similarly, SEM photograph of electron radioactive material layer of cold cathode discharge lamp SEM photograph of electron emissive material layer of comparative example (A) The conceptual diagram in the cross section of the electron-emitting substance layer of an Example, (b) The conceptual diagram in the cross section of the electron-emitting substance layer of a comparative example The principal part expanded sectional view of the modification of the electron radioactive substance layer of the cold cathode discharge lamp which concerns on the 1st Embodiment of this invention. Sectional drawing including the tube axis | shaft of the cold cathode discharge lamp which concerns on the 2nd Embodiment of this invention The disassembled perspective view of the illuminating device which concerns on the 3rd Embodiment of this invention. The partial notch perspective view of the illuminating device which concerns on the 4th Embodiment of this invention. The perspective view of the image display apparatus which concerns on the 5th Embodiment of this invention. (A) The front view of the modification 1 of the cold cathode discharge lamp which concerns on the 1st Embodiment of this invention, (b) The principal part expanded sectional view containing the tube axis of the modification 1 similarly. (A) The principal part expanded sectional view which similarly includes the tube axis of modification 2, (b) The principal part expanded sectional view which similarly includes the tube axis of modification 3. (A) The principal part expanded sectional view which similarly includes the tube axis of the modification 4, (b) The principal part enlarged sectional view which similarly includes the tube axis of the modification 5. Expanded sectional view of the main part including the tube axis of a conventional cold cathode discharge lamp

Explanation of symbols

100, 111, 113, 115, 117, 119, 200 Cold cathode discharge lamp 101 Arc tube 102, 114, 116 Electrode 103, 118, 120 Electron radioactive material layer 104 Phosphor layer 105 Crack 300, 400 Illumination device 500 Image display device

Claims (10)

A low-pressure discharge lamp comprising an arc tube, an electrode provided inside the arc tube, and an electron-emitting material layer provided on a surface of the electrode,
The electron-emitting material layer has a crack on at least a part of a surface thereof, and is a cold cathode discharge lamp. The electrode has a bottomed cylindrical shape,
The cold cathode discharge lamp according to claim 1, wherein the electron-emitting material layer is provided on an inner surface of the electrode. 3. The cold cathode discharge lamp according to claim 2, wherein the electron-emitting material layer is provided from an inner bottom surface of the electrode to a region of 1/3 or less of a length in the axial direction of the electrode. 4. The cold cathode discharge lamp according to claim 2, wherein the crack is formed in at least a portion of the electron-emitting material layer corresponding to an inner bottom surface of the electrode. 5. The crack is formed in at least a portion of the electron-emitting material layer corresponding to the inner side surface of the electrode, and extends from the inner bottom surface of the electrode toward the opening. 2. The cold cathode discharge lamp according to item 1. The cold cathode discharge lamp according to claim 1, wherein the electron-emitting material layer includes a rare earth element. The cold cathode discharge lamp according to claim 6, wherein the rare earth element is at least one of lanthanum (La) and yttrium (Y). The electron emissive material layer is any one of silicon (Si), aluminum (Al), zirconium (Zr), boron (B), zinc (Zn), bismuth (Bi), phosphorus (P), and tin (Sn). The cold cathode discharge lamp according to claim 6, comprising one or more kinds. An illuminating device comprising the cold cathode discharge lamp according to claim 1. An image display device comprising the illumination device according to claim 9.