JP2009164065A - External electrode discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an external electrode discharge lamp excellent in darkness starting characteristic. <P>SOLUTION: The external electrode discharge lamp is provided with a discharge vessel 1 with a discharge space 11 formed inside, a discharge medium sealed in the discharge space 11, a phosphor layer 2 formed on an inner surface of the discharge vessel 1, and external electrodes 3a, 3b formed on an external surface of the discharge vessel 1. At least a part of the inner surface of the phosphor layer 2 is exposed to the discharge space 11, and an initial electron emission layer 4 is formed so that a distance D1 between an end part side of the discharge vessel 1 and a boundary 3' of the external surface electrodes 3a is to be 30 mm or less. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an outer surface electrode discharge lamp used as a light source of a backlight of a liquid crystal television, a notebook personal computer or the like.

  At present, as a light source used for a backlight of a liquid crystal display, an external electrode discharge lamp is becoming mainstream instead of a cold cathode fluorescent lamp. An outer surface electrode discharge lamp is a lamp in which outer surface electrodes are formed at both outer ends of a linear discharge vessel having an airtight discharge space inside, as described in JP-A-2007-53117 (Patent Document 1). It is.

  In this external electrode discharge lamp, there is a problem that the dark start characteristics, that is, the start characteristics of a lamp left in a dark space such as the interior of a backlight housing where no external light is incident are not good. In order to solve this problem, Japanese Unexamined Patent Application Publication No. 2004-253245 (Patent Document 2) and Japanese Unexamined Patent Application Publication No. 2006-19100 (Patent Document 3) describe a phosphor inner surface corresponding to a portion where an external electrode is disposed, An invention has been proposed in which a layer of a cesium compound or the like is formed on the inner surface of a glass tube. Japanese Patent Laid-Open No. 2006-344585 (Patent Document 4) forms a protective layer containing, for example, a cesium compound over almost the entire inner surface of a glass tube, and forms a phosphor layer between external electrodes on the protective layer. An invention has been proposed.

JP 2007-53117 A JP 2004-253245 A JP 2006-19100 A JP 2006-344585 A

  However, as a result of the inventor's test, it has been found that the dark start characteristics are hardly improved in the inventions of Patent Documents 2 to 4. That is, even when a film such as a cesium compound is formed in the glass tube in which the external electrode is formed so as to be exposed to the discharge space, a discharge delay phenomenon occurs.

  An object of the present invention is to provide an outer surface electrode discharge lamp excellent in dark starting characteristics.

  In order to achieve the above object, an external electrode discharge lamp according to the present invention includes a discharge vessel in which a discharge space is formed, a discharge medium sealed in the discharge space, and a fluorescence formed on the inner surface of the discharge vessel. A body layer and an outer surface electrode formed on the outer surface of the discharge vessel, and at least part of the inner surface of the phosphor layer is exposed to the discharge space, and the end side of the discharge vessel and the The initial electron emission layer is formed so that the distance D1 to the boundary of the outer electrode is 30 mm or less.

  ADVANTAGE OF THE INVENTION According to this invention, the outer surface electrode discharge lamp excellent in the dark starting characteristic can be provided.

(First embodiment)
Hereinafter, an outer surface electrode discharge lamp according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall view for explaining an outer surface electrode discharge lamp according to a first embodiment of the present invention, and FIG. 2 is a view for explaining a range of X shown in FIG.

  The container of the outer electrode discharge lamp is composed of a discharge container 1 made of, for example, borosilicate glass. The discharge vessel 1 has an elongated cylindrical shape with both ends sealed, and a discharge space 11 is formed inside. The discharge space 11 is filled with a discharge medium made of mercury Hg and a rare gas. Here, a mixed gas of neon Ne and argon Ar is suitable as the rare gas, and adjustments such as increasing the ratio of argon Ar and improving the startability of the lamp are possible.

A phosphor layer 2 is formed on the inner surface of the discharge vessel 1 in a range that covers the light emission region of the lamp. As the phosphor layer 2, in addition to single-wavelength phosphors that emit light of R (red), G (green), and B (blue), three-wavelength phosphors in which RGB are mixed can be used according to the intended use. . Note that. Alumina Al ₂ O ₃ (particularly α-alumina) may be mixed into the phosphor layer 2.

  Outer electrodes 3a and 3b are formed at both ends of the discharge vessel 1 along the outer surface thereof. The outer surface electrodes 3a and 3b can be formed by, for example, ultrasonic solder dipping of a metal material mainly composed of tin Sn, zinc Zn, and antimony Sb, or a metal cap can be attached to the end portion, It can be formed by covering the end of the metal with solder and connecting them with solder.

  An initial electron emission layer 4 is formed on the inner surface of the phosphor layer 2 so that at least a part of the phosphor layer 2 is exposed to the discharge space 11. The phrase “at least a part thereof is exposed to the discharge space” means that the entire layer does not necessarily have to be exposed, and a part thereof may be covered with another layer. However, in order to obtain the effects of the present invention, it is desirable that the portion of the initial electron emission layer 4 near the boundary 3 ′ of the external electrode 3 a is exposed to the discharge space 11. Further, the initial electron emission layer 4 is formed so that the distance D1 (see FIG. 3) between the end side of the discharge vessel 1 and the boundary 3 ′ of the outer surface electrode 3a is 30 mm or less, preferably 8 mm. It is formed on the inner surface. In the present embodiment, the distance D1 = 0 mm, that is, as shown in FIG. 2, the initial electron emission layer 4 and the boundary 3 'of the outer electrode 3a coincide. On the other hand, it is desirable that the distance D2 between the initial electron emission layer 4 and the center of the discharge vessel 1 with the boundary 3 'of the outer electrode 3a is 30 mm or less. Further, the axial formation length L of the initial electron emission layer 4 determined by the distances D1 and D2 is desirably 1.0 mm or more.

  Further, the initial electron emission layer 4 will be described in detail with reference to FIG. FIG. 4 is a diagram for explaining the range of Y shown in FIG.

  As can be seen from FIG. 4, the phosphor layer 2 and the initial electron emission layer 4 are microscopically formed on the particles 21 constituting the phosphor layer 2 and further on the particles 21. The particles 41 to be stacked are stacked. At this time, the particles 41 (for example, the average particle diameter is 4.5 μm to 10 μm) of the initial electron emission layer 4 are larger than the particles 21 (for example, the average particle diameter is 4.0 μm to 5.0 μm) of the phosphor layer 2. It is desirable to form it to be large, and it is preferable that the average particle diameter of the particles 41 is 1.1 to 2.0 times the average particle diameter of the particles 21.

The initial electron emission layer 4 may be made of a material having excellent initial electron emission properties, such as an aluminum Al, cesium Cs, strontium Sr, or potassium K oxide or compound. That is, cesium sulfate Cs ₂ SO ₄ , cesium acetate CH ₃ COOCs, strontium fluoride SrF ₂ , potassium phosphate K ₃ PO ₄ , aluminum oxide Al ₂ O _{3 and the} like can be used as the initial electron emission layer 4. Of these, Cs compounds that are excellent in initial electron emission properties and the like are particularly suitable.

  Here, a method of forming the initial electron emission layer 4 will be described. The initial electron emission layer 4 can be formed by, for example, a so-called suction coating method in which a material having an initial electron emission property that is slurried from the opening side of the discharge vessel 1 is sucked and applied in the same manner as the application of the phosphor layer 2. . At that time, the thickness and the axial formation length L of the initial electron emission layer 4 can be adjusted by the viscosity of the slurryed material, the amount of suction, and the like. Incidentally, it is not necessary to form the initial electron emission layer 4 on both the outer surface electrodes 3a and 3b. That is, when both the outer surface electrodes 3a and 3b are on the high voltage side, it is sufficient to form the initial electron emission layer 4 on one of them, and one outer surface electrode is set to a high voltage and the other outer electrode is set to a low voltage or ground. The initial electron emission layer 4 may be formed on the high voltage side.

  An example of the outer surface electrode discharge lamp of the present embodiment is shown below. The tests described below are based on this specification unless otherwise specified.

(Example)
Discharge vessel 1; made of borosilicate glass, total length = 733 mm, outer diameter = 3.0 mm, inner diameter = 2.0 mm,
Discharge medium: Mercury Hg, mixed gas of neon Ne and argon Ar = 50 torr,
Phosphor layer 2; RGB three-wavelength phosphor, film thickness = 13 μm, average particle size = 4.0 μm,
Electrodes 3a, 3b; electrode length = 25 mm,
Initial electron emission layer 4; cesium sulfate Cs ₂ SO ₄ , axial formation length L = 10 mm, average particle size = 4.5 μm.

  When the outer surface electrode discharge lamp of the above-mentioned embodiment that was left in the dark for 24 hours was lit in the dark under the lighting conditions of 65 kHz and 2420 Vrms, the discharge start time was 50 msec. It can be seen that the dark start characteristics can be remarkably improved by the present invention as compared with the conventional lamp in which the initial electron emission layer 4 is not formed, that the discharge start time is 10000 msec or more. Moreover, even when this lighting was repeated, the discharge start time was almost the same and there was reproducibility.

  In the present embodiment, such an excellent dark start characteristic was obtained because a large amount of initial electrons were supplied to the discharge space 11 on the lamp center side of the boundary 3 ′ of the external electrode 3a where discharge was started in the external electrode discharge lamp. It is presumed that it was. That is, by forming the initial electron emission layer 4 on the inner surface of the phosphor layer 2 of the part, the initial electron concentration at the discharge start point (near the Z point shown in FIG. 2) is increased, and the discharge probability is increased. This is thought to have led to a reduction in the discharge start time.

  However, even if the initial electron emission layer 4 is formed in the vicinity of the discharge start point, if it is completely covered with a protective film or the like, it is confirmed that the initial electron emission is hindered and the dark starting characteristics are not improved. . Further, if the distance D1 between the end side of the discharge vessel 1 of the initial electron emission layer 4 and the boundary 3 ′ of the outer surface electrode 3a is 30 mm or more, the initial electron concentration in the vicinity of the discharge start point Z cannot be increased. As shown in FIG. 5, the discharge start time is delayed. Therefore, the initial electron emission layer 4 must be formed so that a part thereof is exposed to the discharge space 1 and the distance D1 is 30 mm or less. The distance D1 is desirably 8 mm or less, at which the discharge start time is 1000 msec or less. Further, the end side of the discharge container 1 of the initial electron emission layer 4 coincides with the boundary 3 ′ of the outer electrode 3a (distance D1). = 0 mm) is desirable.

  On the other hand, as for the distance D2 between the center side of the discharge vessel 1 of the initial electron emission layer 4 and the boundary 3 ′ of the outer surface electrode 3a, the dark start characteristics are improved in the portion where the distance D2 is 30 mm or more, as in the result of FIG. Does not contribute much. On the contrary, Cs compounds and the like are non-luminous substances, which causes a decrease in luminous flux. Accordingly, the distance D2 is desirably 30 mm or less. However, it is desirable that the axial formation length L of the initial electron emission layer 4 determined by the distances D1 and D2 is set to be 1.0 mm or more so that the initial electron concentration is sufficiently high.

  Further, when the initial electron emission layer 4 is stacked on the phosphor layer 4 as in the present invention, the particles 41 constituting the initial electron emission layer 4 are larger than the particles 21 constituting the phosphor layer 2. It is desirable to form so that it becomes. This suppresses the movement of the particles 41 into the inner surface of the discharge vessel 1 or the particles 21 due to the impact of rare gas ions or mercury ions during the production of the initial electron emission layer 4 or during lighting, and the initial electron emission. It is for suppressing the fall of property. In addition, if the average particle diameter of the particle 41 is 1.1 times or more than the average particle diameter of the particle 21, the movement of the particle 41 can be particularly suppressed. However, if it exceeds 2.0 times, the particle 21 tends to be peeled off from the particle 41, which is not desirable.

  Therefore, in the first embodiment, a cesium Cs compound is formed as the initial electron emission layer 4 on the inner surface of the phosphor layer 2 so that at least a part of the phosphor layer 2 is exposed to the discharge space 1. The initial electron concentration in the vicinity of the discharge start point Z can be increased by setting the distance D1 between the end side of the discharge vessel 1 of 4 and the boundary 3 ′ of the outer surface electrode 3a to 30 mm or less, preferably 0 mm. Therefore, it is possible to realize an outer surface electrode discharge lamp excellent in dark starting characteristics.

  At that time, the distance D2 between the central side of the discharge vessel 1 of the initial electron emission layer 4 and the boundary 3 ′ of the outer surface electrode 3a is set to 30 mm or less, thereby improving the dark starting characteristics and minimizing the decrease of the luminous flux. can do.

  In addition, since the particles 41 constituting the initial electron emission layer 4 are larger than the particles 21 constituting the phosphor layer 2, it is possible to suppress a decrease in initial electron emission due to the particles 41 moving into the particles 21. it can.

(Second Embodiment)
FIG. 6 is a diagram for explaining an outer electrode discharge lamp according to a second embodiment of the present invention. About each part of embodiment after this, the same part as each part of the outer surface electrode discharge lamp of 1st Embodiment is shown with the same code | symbol, and the description is abbreviate | omitted.

  In the present embodiment, the initial electron emission layer 4 is formed so as to protrude also from the boundary 3 ′ of the outer surface electrode 3 a toward the end portion of the discharge vessel 1. This is to prevent the occurrence of a problem that the initial electron emission layer 4 is not formed near the discharge start point Z due to a manufacturing error. However, in the portion of the discharge vessel 1 in which the initial electron emission layer 4 is formed so as to overlap the external electrode 3a, the glass is scraped by electron collision and a takotsubo-shaped depression is easily formed. The distance D1 between the outer surface electrode 3a and the boundary 3 ′ is preferably −1.5 mm or less (the center side of the discharge vessel 1 from the boundary 3 ′ is positive).

  Therefore, in the second embodiment, the effects of the first embodiment can be obtained, and the occurrence of a problem that the initial electron emission layer 4 is not formed near the discharge start point Z due to a manufacturing error can be prevented.

  The embodiment of the present invention is not limited to the above, and may be modified as follows, for example.

  The present invention can be applied not only to the straight tube type outer surface electrode discharge lamp but also to lamps of U-shape, L-shape, and various other shapes.

  The initial electron emission layer 4 is not limited to being formed in a cylindrical shape, and may be in a partially formed state as long as the initial electron concentration at the discharge start point can be maintained high.

The figure for demonstrating the outer surface electrode discharge lamp of the 1st Embodiment of this invention. The figure for demonstrating the range of X shown by FIG. The figure for demonstrating the case where the initial stage electron emission layer is separated from the boundary of an external electrode. The figure for demonstrating the range of Y shown by FIG. The figure for demonstrating the discharge start time when changing the distance D1 to an electrode boundary and the edge part of an initial stage electron emission layer. The figure for demonstrating the outer surface electrode discharge lamp of the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Discharge vessel 11 Discharge space 2 Phosphor layer 21 Particles 3a and 3b External electrode 3 'Boundary 4 Initial electron emission layer 41 Particle

Claims (5)

A discharge vessel in which a discharge space is formed; a discharge medium enclosed in the discharge space; a phosphor layer formed on the inner surface of the discharge vessel; and an outer electrode formed on the outer surface of the discharge vessel. Equipped,
An initial electron emission layer is formed on the inner surface of the phosphor layer so that at least part of the phosphor layer is exposed to the discharge space, and the distance D1 between the end of the discharge vessel and the boundary of the outer electrode is 30 mm or less. An outer surface electrode discharge lamp characterized by being formed.   The outer surface electrode discharge lamp according to claim 1, wherein the initial electron emission layer is formed across the outer surface electrode.   The outer surface electrode discharge lamp according to claim 1 or 2, wherein a distance D2 between a center side of the discharge vessel of the initial electron emission layer and a boundary between the outer surface electrodes is 30 mm or less.   The said initial stage electron emission layer consists of one or more selected from the oxide or compound of aluminum Al, cesium Cs, strontium Sr, and potassium K, The claim 1 characterized by the above-mentioned. External electrode discharge lamp.   The outer surface electrode discharge lamp according to any one of claims 1 to 4, wherein particles constituting the initial electron emission layer are larger than particles constituting the phosphor layer.

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