JP2010123267A - Cold cathode lamp and light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cold cathode discharge lamp in which an environmental load can be reduced by controlling consumption of mercury due to sputtering and reducing the amount of mercury filled in the bulb and a light-emitting device using this cold cathode discharge lamp. <P>SOLUTION: The cold cathode discharge lamp 1 is provided with a translucent airtight bulb 2 in which rare gas and mercury are filled and a phosphor layer 4 is formed on the inner circumferential face, a pair of cylindrical electrodes 5 formed of Ni or Ni alloy which are installed opposed to at both end parts of the airtight bulb 2, of which one end side is made an aperture part 5a and the other end side is made a bottom end part 5b, and in which the length dimension in axial direction from the aperture part 5b toward the bottom end part 5b is 13 mm or more, and the ratio of the length dimension to the outer diameter dimension is 4 or more, and an electrode lead wire 6 which is jointed to the bottom end part 5b of the cylindrical electrode 5 and supplies power. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cold cathode discharge lamp capable of reducing the amount of mercury enclosed and a light emitting device using the cold cathode discharge lamp.

  Conventionally, a cold cathode discharge lamp has been used as a light source for a backlight used in a liquid crystal display, and an electrode of this cold cathode discharge lamp is widely used with a Ni material that is excellent in molding processability and relatively inexpensive. It has been. However, in this type of cold cathode discharge lamp, a phenomenon of sputtering in which the ionized sealed gas collides with the electrode and the electrode material scatters in the process of discharge during lighting. The electrode material scattered by sputtering is combined with mercury enclosed in the bulb of the discharge lamp to become an alloy, which consumes mercury vapor and reduces the effective mercury amount. As a result, the lifetime of the cold cathode discharge lamp is reduced. In particular, in order to improve the surface brightness of the liquid crystal display, a large amount of discharge current of the discharge lamp flows to increase the light output. For this reason, in the bulb of the discharge lamp, excessive mercury must be enclosed in excess of the amount of mercury necessary to maintain the discharge for the purpose of compensating for the decrease in mercury due to sputtering.

  Therefore, an increase in the number of cold cathode discharge lamps shipped with an increase in demand for liquid crystal displays and the like in recent years has led to an increase in environmental load at least in relation to the amount of mercury.

On the other hand, in order to reduce the sputtering rate of the electrode, reduce mercury consumption, and improve the life of the lamp, there has been proposed an electrode formed of a Ni alloy containing Nb or Ta (see Patent Document 1). ).
JP 2004-235073 A

  However, although it is possible to reduce the sputtering rate in the one disclosed in Patent Document 1, since an electrode material scattered by sputtering is generated, mercury is consumed by this electrode material, and an excessive amount of mercury is generated. Must be enclosed.

  The present invention has been made in view of the above problems. A cold cathode discharge lamp capable of suppressing mercury consumption due to sputtering, reducing the amount of mercury enclosed in a bulb, and reducing the environmental load, and the cold cathode discharge lamp. An object is to provide a light emitting device used.

  The cold cathode discharge lamp according to claim 1 is a translucent airtight bulb in which a rare gas and mercury are enclosed, and a phosphor layer is formed on an inner peripheral surface thereof; opposed to both ends of the airtight bulb. And the other end side is the bottom end, the length in the axial direction from the opening toward the bottom end is 13 mm or more, and the length is relative to the outer diameter. A cylindrical electrode formed of Ni or a Ni alloy having a ratio of 4 or more; and an electrode lead wire that is joined to the bottom end portion of the cylindrical electrode and supplies power. As the airtight valve, a linear shape, a U-shape, an L-shape, a U-shape or the like can be applied, and the shape is not particularly limited.

  A light emitting device according to a second aspect of the present invention includes: a device main body; and the cold cathode discharge lamp according to the first aspect mounted on the device main body. The light emitting device is a concept including a display device and a so-called lighting fixture that illuminates a space.

  According to the first aspect of the present invention, it is possible to provide a cold cathode discharge lamp that can suppress the consumption of mercury by sputtering and reduce the amount of mercury enclosed in the bulb, thereby reducing the environmental load.

  According to invention of Claim 2, the light-emitting device which has an effect of the cold cathode discharge lamp of Claim 1 can be provided.

  Hereinafter, a cold cathode discharge lamp according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. In addition, the same code | symbol is attached | subjected to the same part in each figure, and the overlapping description is abbreviate | omitted. FIG. 1 is a cross-sectional view showing a cold cathode discharge lamp, and FIGS. 2 and 3 are schematic cross-sectional views for explaining the embodiment.

  First, a cold cathode discharge lamp that is a premise of the present embodiment will be described. As shown in FIG. 1, the cold cathode discharge lamp 1 includes a glass bulb 2 and an electrode unit 3 as a translucent airtight bulb. The glass bulb 2 is formed from semi-hard glass. In addition, not only semi-hard glass but hard glass and soft glass can be applied, and the composition of the glass such as boro-silicate glass and soda glass is not particularly limited. When the cold cathode discharge lamp 1 is used as a light source for a backlight of a liquid crystal panel, several types of glass bulbs 2 having an outer diameter of φ1.5 mm to φ5.0 mm are prepared. It is used properly according to the specifications. And the thing of about 150 mm-1300 mm in length is prepared, and the dimension exists in the tendency for diameter reduction and lengthening. The glass bulb 2 is sealed at both ends to form a sealed space, and is filled with a rare gas such as Ar, Xe, Ne, and mercury vapor. A fluorescent film 4 of a phosphor layer is formed on the inner peripheral surface of the glass bulb 2. The phosphor film 4 may be a halophosphate phosphor, a rare earth metal oxide phosphor, or the like.

  The electrode unit 3 includes a cylindrical electrode 5 and an electrode lead wire 6 joined to feed power to the cylindrical electrode 5. The electrode 5 has an outer diameter slightly smaller than the inner diameter of the glass bulb 2, and has a cup shape with one end side as an opening 5a and the other end side as a bottom end portion 5b. The cathode fall voltage can be lowered by the hollow cathode effect. The electrode 5 is made of Ni or a Ni alloy, and is formed by pressing a plate material or cold forging a wire.

  The electrode lead wire 6 includes a sealing member 6a and a lead member 6b, and the distal end side of the sealing member 6a is joined to the bottom end portion 5b of the electrode 5 by laser beam welding or the like. Moreover, the sealing member 6a and the lead member 6b are joined by welding. For the sealing member 6a, a Kov (Kovar) wire is used, and for the lead member 6b, a jumet wire having a nickel iron alloy covered with copper is used.

  The electrode unit 3 configured in this manner is sealed in a pair at both ends of the glass bulb 2 and is disposed with the openings 5a of the cup-shaped electrode 5 facing each other. Line 6 is derived. Further, when sealing the electrode unit 3 to the glass bulb 2, the bead glass 7 is welded to the sealing member 6a prior to sealing. When the electrode unit 3 is joined to the glass bulb 2, the bead glass 7 and the end of the glass bulb 2 are melted and sealed.

  Next, in order to reduce the amount of mercury enclosed in the glass bulb 2 of the cold cathode discharge lamp 1, the present inventor conducted experiments and measurements as follows, and tried investigation and analysis.

  (Measurement Example 1) The amount of mercury contained in the initial product of the cold cathode discharge lamp 1 and the product in the life test that had been turned on for a predetermined time and passed the life test were measured. In addition, with regard to products that have undergone a life test, the amount of mercury deposited was measured at each site in order to determine where the mercury was consumed. The result is shown in the table below.

  Here, the mercury content of the initial product is 3.9 mg. As shown in FIG. 2, the “bulb blackened portion” in the part refers to a blackened portion Bk on the inner surface of the glass bulb 2 generated in the vicinity of the openings 5 a of the pair of electrodes 5 in the life test progress product. The “non-blackened phosphor layer portion” mainly refers to the phosphor layer portion on the inner surface of the glass bulb 2 excluding the blackened portion Bk. From this result, it was found that the enclosed mercury was concentrated in the valve blackening portion Bk. Furthermore, as a result of analyzing the blackened portion Bk, the same element as the material of the electrode 5 is detected from the blackened portion Bk, and this is an electrode material that is spattered by the electrode 5 being sputtered during the discharge process at the time of lighting. There was found. Further, it was confirmed that the sputtered electrode material is active because it is scattered in a fine molecular state, reacts with mercury vapor, and adheres to the blackened portion Bk as a compound having a low vapor pressure.

  Therefore, it is considered that the initial mercury sealing amount can be reduced by preventing or suppressing the reaction between the sputtered electrode material and mercury. It was found by X-ray imaging which part of the cylindrical electrode 5 was sputtered, and the portion St in the vicinity of the bottom end portion 5b on the inner peripheral surface was selectively sputtered.

(Measurement Example 2) Next, as shown in FIG. 3, specifically, the electrode has an outer diameter of φ2.1 mm, a wall thickness of t0.1 mm, and an axial length from the opening 5a to the bottom end 5b. A cylindrical electrode 5 made of three kinds of Ni alloys having dimensions L ₁ = 5 mm (FIG. 3A), L ₂ = 7 mm (FIG. 3B), and L ₃ = 10 mm (FIG. 3C) is prepared. Then, a Kov line sealing member 6 a having an outer diameter of 0.8 mm and a length of 4 mm was joined to the cylindrical electrode 5 to constitute the electrode unit 3. These electrode units 3 are sealed at both ends of a glass bulb 2 having an outer diameter of 3.4 mm and a length of 1000 mm, and Ne—Ar 6 × 10 ³ Pa and mercury 3.9 mg are enclosed as rare gases. A cold cathode discharge lamp 1 was manufactured. These cold cathode discharge lamps 1 were lit for 6000 hours at a lamp current of 10 mA, and the appearance was observed and the mercury contained in the bulb was analyzed. In this actual measurement, first, measurement analysis is performed for a lamp having the length of the cylindrical electrode 5 of L ₁ = 5 mm (FIG. 3A) and L ₂ = 7 mm (FIG. 3B), and the result is shown. Based on this, a measurement analysis was performed on a lamp having a length L ₃ = 10 mm (FIG. 3C).

  Here, sampling at each part is performed by cutting the glass bulb 2 at a position P1 of 5 mm from the sealing portions at both ends of the glass bulb 2 to take out the electrode 5 as an “electrode portion” and at a position 15 mm from the sealing portion. The glass bulb 2 was cut at P2, and this portion was designated as “bulb blackened portion” A, and the remaining central portion of the glass bulb 2 was designated as “non-blackened phosphor layer portion”.

As shown in FIGS. 3 (a) and 3 (b), the position where the sputtering occurs in the lamp with the cylindrical electrode 5 having a length dimension of L ₁ = 5 mm and L ₂ = 7 mm remains unchanged. A portion St in the vicinity of the bottom end portion 5b of the inner peripheral surface 5 was selectively sputtered. Further, the length dimension of the blackened portion Bk on the inner surface of the glass bulb 2 generated in the vicinity of the opening 5a of the electrode 5 is different between the lamp with the length dimension of the electrode 5 of L ₁ = 5 mm and the lamp with L ₂ = 7 mm. The lamp of L ₁ = 5 mm is about 3 mm, the lamp of L ₂ = 7 mm is about 1 mm, and the lamp of L ₁ = 5 mm is longer, the length dimension of the electrode 5 and the length dimension of the blackened portion Bk Was found to be the same at about 8 mm. Further, it can be seen that, as in the first measurement example, the enclosed mercury is concentrated in the valve blackening portion Bk. Therefore, since the position where the sputtering of the electrode 5 occurs is the same and the scattering position of the scattering material of the electrode 5 is the same, the scattering material of the electrode 5 physically comes from the position where the sputtering occurs. If the length of the cylindrical electrode 5 is increased and the scattering material of the electrode 5 is accommodated in the inner periphery of the electrode 5, the scattering material will not combine with mercury to form a compound. it is conceivable that.

Based on the above knowledge, as shown in FIG. 3C, it is considered that in the lamp with the length L ₃ of the cylindrical electrode 5 = 10 mm, the scattered material of the electrode 5 is contained in the inner periphery of the electrode 5. In the “bulb blackening portion” A of the glass bulb 2, no blackening is observed, and almost no mercury is detected.

(Actual measurement example 3) Although not shown, the same measurement as in the actual measurement example 2 was performed by changing conditions such as the dimensions of the cylindrical electrode 5. Outer diameter φ2.7mm, thickness dimension T0.1Mm, length _{L 1 = 5mm, L 2 =} 7mm, L 3 = 10mm, prepared cylindrical electrode 5 made of four kinds of Ni alloy L 4 = 15 mm Then, a Kov line sealing member 6 a having an outer diameter of 0.8 mm and a length of 4 mm was joined to the cylindrical electrode 5 to constitute the electrode unit 3. These electrode units 3 are sealed at both ends of a glass bulb 2 having an outer diameter of 3.4 mm and a length of 1000 mm, and Ne—Ar 6 × 10 ³ Pa and mercury 3.9 mg are enclosed as rare gases. A cold cathode discharge lamp 1 was manufactured. These cold cathode discharge lamps 1 were lit for 6000 hours at a lamp current of 13 mA, and the appearance was observed and the mercury contained in the bulb was analyzed.

As can be seen from this actual measurement example, the blackening of the glass bulb 2 occurs in the lamp having the length dimensions L ₁ = 5 mm and L ₂ = 7 mm of the electrode 5, and the glass bulb generated in the vicinity of the opening 5 a of the electrode 5. The length of the blackened portion Bk on the inner surface of the electrode ₂ is about 3 mm for the lamp with the electrode 5 having a length L ₁ = 5 mm and about 1 mm for the lamp with the L ₂ = 7 mm. The sum of the lengths of the conversion parts Bk was the same at about 8 mm. It can also be seen that the enclosed mercury is concentrated in the valve blackening portion Bk. On the other hand, blackening of the glass bulb 2 is not observed in the lamp having the length dimensions L ₃ = 10 mm and L ₄ = 15 mm of the electrode 5. Further, when the inner peripheral portion of the electrode 5 was examined, scattered substances of the electrode 5 were adhered, but mercury was hardly detected in these scattered substances. The reason for the lack of mercury bonding can be explained as follows.

  Electrons emitted from the inner periphery of the electrode 5 as a cathode are accelerated by an electric field, and obtain energy to ionize gas molecules existing in the space. This ionized gas becomes positive ions. Since electrons are emitted one after another from the inner peripheral portion of the electrode 5, positive ions are also generated accordingly, and mercury ions are electrically excluded from the inner peripheral portion of the electrode 5 and do not exist. Therefore, even if the scattered material of the electrode 5 accumulates and settles on the inner peripheral portion of the electrode 5, mercury does not bind to the scattered material. In other words, if the scattering material of the electrode 5 is accommodated in the inner peripheral portion of the electrode 5, the scattering material does not combine with mercury to form a compound.

  (Consideration) According to the above measurement example, it was found that the amount of enclosed mercury can be reduced by setting the length dimension of the cylindrical electrode 5 so that the scattering material of the electrode 5 is accommodated in the inner peripheral portion of the electrode 5. . Specifically, since the sum of the length dimension of the electrode 5 and the length dimension of the blackened portion Bk is about 8 mm, the length of the cylindrical electrode 5 is considered when this is considered as the flying distance of the scattered material of the electrode 5. If the size is about 8 mm, it is considered that most of the scattered material can be accommodated in the inner peripheral portion of the electrode 5. Furthermore, according to the measurement example 3, the ratio of the length dimension to the outer diameter dimension of the cylindrical electrode 5, that is, the length dimension / outer diameter dimension is 8 mm / 2.7 mm≈3. Therefore, by setting the length dimension of the cylindrical electrode 5 to 8 mm or more and the ratio of the outer diameter dimension to the length dimension to 3 or more, consumption of mercury due to sputtering can be suppressed and the amount of enclosed mercury can be reduced. . Based on this, in order to improve the certainty so that the scattering material of the electrode 5 can be accommodated in the inner peripheral portion of the electrode 5, when inferred from the measurement examples 2 and 3, the length dimension of the cylindrical electrode 5 is 13 mm or more, The ratio of the length dimension to the outer diameter dimension is preferably set to 4 or more.

  As described above, according to the present embodiment, as described in the above consideration, the length dimension of the cylindrical electrode 5 is set so that the scattering material of the electrode 5 is accommodated in the inner peripheral portion of the electrode 5. Thus, it is possible to provide the cold cathode discharge lamp 1 capable of suppressing mercury consumption due to the reduction of the amount of enclosed mercury.

  Next, an embodiment of the light emitting device of the present invention will be described. Although not shown, the discharge lamp 1 of the above embodiment can be mounted on the apparatus body and configured as a light emitting device. Here, the light emitting device is a concept including a display device and a lighting fixture that illuminates a so-called space. For example, the present invention can be applied to various display devices such as a backlight device of a liquid crystal panel, and lighting equipment used indoors or outdoors. In the backlight device, any of a direct method, a side light method, and the like can be applied. According to such a light emitting device, it is possible to provide a light emitting device that exhibits the effects of the above embodiment.

It is sectional drawing which shows a cold cathode discharge lamp. It is typical sectional drawing for demonstrating the cold cathode discharge lamp which concerns on embodiment of this invention. It is a typical sectional view for explaining a cold cathode discharge lamp concerning an embodiment similarly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cold cathode discharge lamp, 2 ... Translucent airtight bulb (glass bulb),
3 ... electrode unit, 4 ... phosphor layer, 5 ... cylindrical electrode,
5a ... opening, 5b ... bottom end, 6 ... electrode lead wire

The cold cathode discharge lamp according to claim 1 is a translucent airtight bulb in which a rare gas and mercury are enclosed, and a phosphor layer is formed on an inner peripheral surface thereof; opposed to both ends of the airtight bulb. And the other end side is the bottom end, the length in the axial direction from the opening toward the bottom end is 13 mm or more, and the length is relative to the outer diameter. A cylindrical electrode having a flat cross-section along the axial direction and formed of Ni or a Ni alloy having a ratio of 4 or more; an electrode lead wire joined to the bottom end of the cylindrical electrode to supply power; It is characterized by comprising. As the airtight valve, a linear shape, a U-shape, an L-shape, a U-shape or the like can be applied, and the shape is not particularly limited.

Here, sampling at each part is performed by cutting the glass bulb 2 at a position P1 of 5 mm from the sealing portions at both ends of the glass bulb 2 to take out the electrode 5 as an “electrode portion” and at a position 15 mm from the sealing portion. The glass bulb 2 was cut at P2, and this portion was designated as “bulb blackened portion” A, and the remaining central portion of the glass bulb 2 was designated as “non-blackened phosphor layer portion” B.

The cold cathode discharge lamp according to claim 1 is a translucent airtight bulb in which a rare gas and mercury are enclosed, and a phosphor layer is formed on an inner peripheral surface thereof; opposed to both ends of the airtight bulb. And the other end side is the bottom end, the length in the axial direction from the opening toward the bottom end is 13 mm or more, and the length is relative to the outer diameter. A cylindrical electrode made of Ni or Ni alloy having a ratio of 4 or more, formed by pressing a plate material or cold forging a wire, and having a flat inner surface in a cross section along the axial direction; And an electrode lead wire that is joined to the bottom end portion and supplies power. As the airtight valve, a linear shape, a U-shape, an L-shape, a U-shape or the like can be applied, and the shape is not particularly limited.

Claims (2)

A light-transmitting airtight valve in which a rare gas and mercury are enclosed, and a phosphor layer is formed on the inner peripheral surface;
A pair of the airtight valves are sealed opposite to both end portions, one end side is an opening portion, the other end side is a bottom end portion, and an axial length dimension from the opening portion toward the bottom end portion is 13 mm or more. A cylindrical electrode formed of Ni or a Ni alloy having a ratio of a length dimension to an outer diameter dimension of 4 or more;
An electrode lead wire that is joined to the bottom end of the cylindrical electrode and feeds power;
A cold cathode discharge lamp comprising: The device body;
The cold cathode discharge lamp according to claim 1 mounted on the apparatus body;
A light-emitting device comprising:

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