JP5036465B2 - Hollow cathode manufacturing jig and manufacturing method - Google Patents

Description

  The present invention relates to a jig used for producing a hollow cathode, a method for producing a hollow cathode using the jig, and a hollow cathode produced by the production method.

  Conventionally, a cold cathode fluorescent lamp has been mainly used as a light source of a backlight for displaying images clearly and finely in a liquid crystal display device such as a liquid crystal television or a liquid crystal display. Since cold cathode fluorescent lamps can use plate-like, cylindrical or rod-like electrodes, the electrode structure is simpler than that of hot-cathode fluorescent lamps using coiled filament electrodes, and it is expected that the lamps will be made thin. Along with that, liquid crystal display devices can be expected to be miniaturized.

  However, in recent years, with the improvement in performance of liquid crystal display devices, there has been a strong demand for higher luminance, lower power consumption, and downsizing of fluorescent lamps as light sources (non-native). Patent Document 1).

  The design element of the fluorescent lamp includes an electrode structure and an electrode material. The cold cathode electrode has the advantages of long life and easy tube formation due to its structure, but conversely, the current density is small and the electrode loss is large, so that high brightness and high efficiency (low power consumption) are achieved. (See Non-Patent Document 1).

  Conventionally, Ni that is excellent in workability has been mainly used as an electrode material for the cold cathode electrode. Ni is less expensive than high melting point materials such as Mo and Nb, but is more expensive than general-purpose materials, and has a problem in terms of reducing the cost of fluorescent lamps.

  It has been conventionally known that adopting an electrode structure or an electrode material that easily emits electrons from an electrode is an effective measure for solving the above-described problems, and various proposals have been made so far ( For example, see Patent Documents 1 to 4).

  In Patent Document 1, in a cold cathode composed of an inner electrode and an outer electrode surrounding the inner electrode, the inner electrode is made to have a work function that is higher than that of the metal constituting the outer electrode (at least one of W, Ni, Cu, and Fe). It is described that it is composed of a low metal (at least one of Zr and Al).

  Patent Document 2 discloses a disk-shaped or bottomed-cylindrical shape made of Al, Zr, or an Al-Zr alloy having a small work function at the cylindrical inner bottom of a cylindrical electrode made of Ni or Ni-Fe alloy. A cold cathode provided with an internal electrode is described.

  In this way, when an electrode made of a metal having a low work function is used in combination, the work function is lower than that in the case where the entire electrode is made of only Ni, so that electrons can be easily emitted and taken in, and the cathode fall voltage is low. Therefore, the lamp current can be increased without increasing the power consumption and heat generation.

  However, Al and Zr are metals that have the property of easily producing mercury amalgam, and electrode wear due to the sputtering phenomenon that inevitably occurs on the electrode surface, and generation of mercury amalgam is inevitable, and the life of the fluorescent lamp is extended. Has its limits.

  Patent Document 3 describes an electrode in which an electrode coating layer made of an insulator that functions as a dielectric when a fluorescent lamp is turned on is formed on a surface, and further, a layer made of an electron-emitting material is formed thereon. ing. However, the electrode functions as expected while the electron-emitting substance is present, but the function decreases as the electron-emitting substance is consumed, so there is a limit to increasing the luminance and life of the fluorescent lamp.

  Patent Document 4 describes a cold cathode in which the electrode surface is made of one or more kinds of carbides of Zr, W, Ta, Ti, Nb, Hf, and Mo, which makes it difficult to form mercury amalgam, based on the above limitations. ing. Although this cold cathode can reduce the size and increase the brightness of the fluorescent lamp, it has not yet reached the level of high brightness, low power consumption, and miniaturization that are strongly demanded in recent years for fluorescent lamps. Also, there is a limit in terms of extending the life.

  In recent years, field emission cold cathodes having a carbon nanotube film formed on the surface have been proposed as electrodes capable of operating under a low voltage and obtaining high luminance (see Patent Documents 5 to 7). However, the cathode is a planar electrode, and a method for forming a carbon film on the inner surface of the hollow electrode cylinder has not been developed.

Japanese Patent Laid-Open No. 09-204899 JP 2002-117804 A JP 2004-207183 A Japanese Patent Laying-Open No. 2005-085472 JP 2001-015077 A JP 2004-281388 A JP 2007-188862 A Optical technology information magazine "Light Edge" No. 2 / Special feature LCD backlight source (issued in spring 1995)

  If a carbon film can be formed on the cylindrical inner surface of the hollow electrode, the fluorescent lamps will be made thinner, higher brightness, and lower power consumption, and liquid crystal display devices will be further miniaturized. can do. Then, this invention makes it a subject to form a vapor deposition carbon film | membrane on the cylinder inner surface of a hollow electrode.

  The inventors of the present invention have intensively studied to solve the above problems using a plasma deposition method. As a result, (i) a hollow cylindrical cathode member with one end closed or a hollow cathode member provided with a connection terminal on the outer bottom of the cylinder is prepared, and (ii) the hollow cathode member is mounted on a jig having a specific structure. Then, when plasma deposition was performed, it was found that a carbon film could be formed only on the inner surface of the hollow electrode cylinder. The formation of the carbon film by plasma deposition will be described later.

  This invention was made | formed based on the said knowledge, and the summary is as follows.

(1) A jig used for manufacturing a hollow cathode provided with a connection terminal on the outer bottom of a cylinder and provided with a vapor deposition carbon film on the inner surface of the cylinder,
(I) a conductive rectangular plate formed by arc-shaped at the upper end of the short side,
(Ii) Along the long side surface of the rectangular plate-shaped body,
(Ii-1) open on the side of the long side, and
(Ii-2) Member housing that accommodates a cylindrical hollow cathode member with one end closed or a hollow cathode member having a connection terminal on the outer bottom of a cylinder with one end closed in a contact state perpendicular to the long side surface A jig for manufacturing a hollow cathode, wherein holes are formed.

  (2) The rectangular plate-like body has a melting point of 800 ° C. or higher, the same metal material as that of the hollow cathode member, a metal material having the same thermal expansion coefficient as that of the hollow cathode member, and the thermal expansion of the hollow cathode member. The hollow cathode manufacturing jig according to (1), wherein the jig is made of a metal material having a coefficient of thermal expansion smaller than the coefficient.

  (3) The rectangular plate-like body is a conductive ceramic material having a thermal expansion coefficient substantially the same as that of the hollow cathode member, or a conductive material having a thermal expansion coefficient smaller than that of the hollow cathode member. The jig for manufacturing a hollow cathode according to (1), which is made of a ceramic material.

  (4) The hollow cathode according to any one of (1) to (3), wherein the member accommodation holes are arranged in a line along a long side surface of the rectangular plate-like body. Jig for manufacturing.

  (5) The said member accommodation hole is arrange | positioned by the upper and lower sides and the multiple rows along the long side surface of the said rectangular plate-shaped object, In any one of said (1)-(3) characterized by the above-mentioned. A jig for manufacturing a hollow cathode.

  (6) A side mask member having a circular hole processed so as to cover an end of a cylinder whose one end is closed is attached to a long side surface of the rectangular plate-like body. The jig for manufacturing a hollow electrode according to any one of the above.

(7) A method for producing a hollow cathode using the hollow cathode production jig according to any one of (1) to (6),
(I) A cylindrical hollow cathode member with one end closed, or a hollow cathode member having a connection terminal on the outer bottom of the cylinder with one end closed, is mounted in the member receiving hole of the manufacturing jig,
(Ii) A manufacturing jig equipped with a hollow cathode member is placed on the electrode on the anode side of the plasma deposition apparatus,
(Iii) forming a plasma atmosphere containing carbon radicals around the manufacturing jig, and forming a carbon film only on the inner surface of the hollow cathode member cylinder;
A method for producing a hollow cathode, comprising:

  (8) The method for manufacturing a hollow electrode according to (7), wherein the hollow cathode member is made of any one of Ni, Nb, Mo, Fe, and alloys thereof.

  (9) The method for producing a hollow cathode according to (7) or (8), wherein the carbon film is a carbon film having a nanostructure.

  According to the present invention, it is possible to further promote downsizing, high brightness, and low power consumption of a fluorescent lamp and achieve further downsizing of a liquid crystal display device.

  The present invention will be described with reference to the drawings.

  First, FIG. 1 shows a manufacturing process of a conventional hollow electrode for a fluorescent lamp. The cylindrical member 1, the electrode terminal 2, and the lead wire 3 made of Ni, Mo, Zr, W, Nb, or an alloy thereof are joined and integrated by welding or the like. Next, a glass bead 4 for sealing the electrode in a fluorescent lamp and fixing it is formed on the electrode terminal 2.

  In the conventional process shown in FIG. 1, when the cylindrical member 1 having a carbon film formed on the inner surface is used, the carbon film disappears due to heat generated when the cylindrical member 1 and the electrode terminal 2 are welded. The formation of the glass beads 4 in the next step is usually performed in the air using an oxyhydrogen flame, but the carbon film disappears further by the heat and atmosphere at that time.

  Therefore, the present inventors have developed a manufacturing process of a hollow electrode for a fluorescent lamp because the carbon film disappears during manufacturing even when the cylindrical member 1 having a carbon film formed on the inner surface is used. The manufacturing process is shown in FIG.

  In the manufacturing process shown in FIG. 2, a cylindrical member 1a having a terminal member 2a provided on the outer bottom portion of the cylinder 1b is prepared, and a carbon film is formed only on the inner surface of the cylinder 1b by the plasma deposition apparatus 7 (this formation is performed). The film will be described later.) Thereafter, the lead wire 3 is separately joined to the terminal member 2a, and the electrode terminal 2b on which the glass bead 4 is formed is further fitted, and the fitted outer peripheral portion is welded.

  In addition, you may perform the joining of the lead wire 3 to the electrode terminal 2b, and formation of the glass bead 4 by a conventional method.

  In the joining of the cylindrical member 1a and the electrode terminal 2b, if the fitting form of fitting-welding is adopted, the welding only needs to weld the fitting outer peripheral part, so that the amount of heat transfer to the cylindrical member 1a is reduced, and as a result. The cylindrical member 1a and the electrode terminal 2b can be joined without damaging the carbon film formed on the inner surface of the cylinder 1b. In addition, this inventor confirmed that the insertion-welding junction was sufficient in terms of strength.

  Here, a method for forming a carbon film only on the inner surface of the cylinder 1b of the cylindrical member 1a will be described.

  Carbon film formation is basically performed by plasma deposition, but it is only performed on the inner surface of a cylinder having the required inner diameter and depth, so it is different from film formation on a planar electrode. Techniques and means are not simple.

  As a result of intensive studies, the present inventors have found that a carbon film can be formed only on the cylindrical inner surface of a cylindrical member by plasma deposition using the jig having the structure shown in FIG. .

The main body of the jig shown in FIG. 3 (hereinafter sometimes referred to as “the jig of the present invention”) is composed of a conductive rectangular plate-like body 5 along the long side surface thereof.
(Ii-1) open on the side of the long side, and
(Ii-2) A cylindrical hollow cathode member with one end closed, or a hollow cathode member (see FIG. 2) having a connection terminal on the outer bottom of a cylinder with one end closed, in close contact with the long side surface The member accommodation hole 6 accommodated in the state is formed.

  The carbon film is formed by placing the jig of the present invention on the anode side electrode of the plasma vapor deposition apparatus in order to suppress the plasma discharge from concentrating on the upper end of the short side of the rectangular plate 5. The upper end portion is formed in an arc shape with a required radius of curvature R.

  In addition, although it is not necessary to give a special process to the lower end part of the short side of the rectangular plate-shaped body 5, and the upper end part and lower end part of a long side, it is preferable to perform the process of a chamfering grade.

  In FIG. 3, the member accommodation holes 6 are arranged in a line along the long side surface of the rectangular plate-like body 5. However, the member accommodation hole 6 extends along the long side surface of the rectangular plate-like body. The upper and lower sides may be arranged in a plurality of rows.

  The rectangular plate-like body 5 is placed on the anode side electrode of the plasma deposition apparatus, and is integrated with the electrode to achieve film formation only on the cylindrical inner surface of the cylindrical member. However, it may be made of a conductive ceramic material. The metal material is preferably a metal material having a melting point of 800 ° C. or higher so that it can withstand the plasma atmosphere temperature.

  In order to achieve film formation only on the inner surface of the cylinder, the adhesion between the hollow cathode member and the member accommodation hole is ensured, and carbon must penetrate between the outer side of the hollow cathode member cylinder and the member accommodation hole. There is a need to prevent. Therefore, the rectangular plate-like body 5 is made of the same metal material as the metal material of the hollow cathode member, or a metal material whose thermal expansion coefficient is substantially the same as or smaller than that of the hollow cathode member.

  If the gap between the outside of the hollow cathode member cylinder and the hollow cathode member is 0.1 mm or more (normal gap), a carbon film is formed outside the cylinder. According to the experiments by the present inventors, the gap is preferably 0.08 mm or less. If the gap is 0.08 mm or less, sufficient adhesion between the hollow cathode member and the member receiving hole can be ensured, and carbon can surely enter between the outside of the hollow cathode member cylinder and the member receiving hole. Can be prevented.

  Further, in order to prevent carbon from entering between the outer side of the cylinder of the hollow cathode member and the member accommodation hole, and to prevent carbon from being deposited on the end of the cylinder, as shown in FIG. After the hollow cathode member is accommodated in the member accommodating hole 6, a side mask member 12 having a circular hole 13 having a diameter φ processed so as to cover the end of the cylinder 1b is attached to the long side surface of the rectangular plate-like body 5. May be. The attachment means (not shown) may be a known means.

  FIG. 4A shows a mode in which a side mask member 12 having a circular hole 13 having a diameter φ is attached. The diameter φ of the circular hole 13 is the same as the inner diameter d of the cylinder 1b or smaller than the inner diameter d of the cylinder 1b. If the diameter φ of the circular hole 13 is too smaller than the inner diameter d of the cylinder 1b, the penetration of carbon radicals (described later) into the cylinder 1b is prevented and the formation of the carbon film is inhibited. Set appropriately within the range that does not interfere. The diameter φ of the circular hole 13 is preferably about (the inner diameter d−0.05 mm of the cylinder 1b).

  FIG. 4B shows a mode in which a side mask member 12 having a circular hole 13 having a conical diameter φ is attached to the cylinder 1b side. The diameter φ of the circular hole 13 is made smaller than the inner diameter d of the cylinder 1b. However, if it is too small, the penetration of carbon radicals into the cylinder 1b is prevented and the formation of the carbon film is inhibited. Set appropriately within the range that does not interfere. In addition, it is preferable that the diameter φ of the conical circular hole 13 is about (the inner diameter d−0.1 mm of the cylinder 1b).

  The material of the side mask member is not particularly limited, but the side mask member is integrated with the rectangular plate and functions as a jig for manufacturing the hollow cathode. The same material as the body is preferred. Note that the thickness of the side mask member is appropriately set within a range that does not hinder the penetration of carbon radicals into the cylinder 1b.

  As the conductive ceramic material, a ceramic material having a thermal expansion coefficient substantially equal to or smaller than that of the hollow cathode member is preferable as in the case of a metal material.

  As described above, the jig of the present invention is placed on the anode side electrode of the plasma deposition apparatus and is integrated with the electrode to achieve film formation only on the cylindrical inner surface of the cylindrical member. The dimensions (long side: L, short side: W, thickness: T) may be appropriately set in consideration of (i) the number and inner diameter of the member housing holes to be disposed, and (ii) the electrode dimensions.

  The inner diameter of the member receiving hole is set in consideration of the outer diameter of the hollow cathode member cylinder (that is, the outer diameter of the hollow cathode) and the gap between the outer side of the cylinder and the member receiving hole. The outer diameter of the hollow cathode is about 3 mm or less for fluorescent lamps, but since the hollow cathode can be used for other purposes, the inner diameter of the member receiving hole is not limited to a specific range. Absent.

  According to the test results of the present inventors, for example, when 12 member receiving holes having an inner diameter of about 2.7 mm and a depth of about 5 mm are formed on one side as shown in FIG. 3, the long side of the rectangular plate-shaped body The length L, the short side length W, and the thickness T are preferably about 50 to 54 mm, 25 to 30 mm, and 4 mm, respectively.

  The cylinder of the hollow cathode member accommodated in the member accommodation hole in close contact is preferably made of any one of Ni, Nb, Mo, Fe, and alloys thereof. Among these, austenitic stainless steel is advantageous over other cylindrical materials in terms of workability and cost.

  In the present invention, the jig of the present invention in which the hollow cathode member is mounted in the member accommodation hole is placed on the anode side electrode of the plasma deposition apparatus (see FIG. 2), and the chamber of the plasma deposition apparatus (the electrode is placed in this). Hydrogen containing methane is introduced into the gas, and the methane is decomposed by plasma discharge to generate carbon radicals.

  And in plasma, the electric field distribution which becomes parallel between electrodes is formed, The force which moves to a carbon radical in a horizontal direction is given using this.

  Film formation only on the inner surface of the cylinder of the hollow cathode member can be achieved by the synergistic effect of the structural features of the jig of the present invention and the horizontal movement of the carbon radicals.

  Since the carbon film formed using the jig of the present invention is formed in a plasma atmosphere, carbon nanotube (CNT), carbon nanowall (CNW), carbon nao fiber (CNF), and carbon nano It is a carbon film having one or more types of complex (CNX) nanostructures.

  A hollow cathode produced by forming a carbon film only on the cylindrical inner surface of a hollow cathode member cylinder using the jig of the present invention (hereinafter referred to as “the cathode of the present invention”) has a discharge initiation voltage and It is an extremely excellent cathode in reducing power consumption.

  Next, examples of the present invention will be described. The conditions of the examples are one example of conditions adopted for confirming the feasibility and effects of the present invention, and the present invention is limited to this one example of conditions. Is not to be done. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.

(Example)
Using the jig of the present invention (FIG. 3), H ₂ containing 4% CH ₄ was introduced into the chamber, the chamber pressure (film formation pressure) was kept at 80 Torr, and plasma discharge was performed at a discharge power of 5 kW for 5 minutes. A carbon film was formed on the inner surface of a cylinder having an outer diameter of 2.7 mm, an inner diameter of 1.8 mm, and a length of 5 mm to produce a hollow cathode.

  As shown in FIG. 5, two hollow cathodes 8 are attached to both ends of a glass tube 9 having an outer diameter of 3 mm and a length of 300 mm to produce a fluorescent lamp 10 and connected to a supply / exhaust device (not shown). Placed in tube 11.

  Next, Ne containing 4% Ar was supplied into the measurement glass tube 11, the internal pressure of the fluorescent lamp 10 was maintained at 10,000 Pa, and a voltage was applied between the electrodes to induce discharge. Even after the voltage was increased and the discharge was stabilized, the voltage was increased so that the current became 5 mA, and further 7 mA, and the discharge start voltage and the lamp voltage were measured from the oscilloscope waveform of the voltage. The power loss was calculated by measuring the voltage and current on the primary side of the DC stabilized power supply used.

  In addition, in order to confirm the efficiency of the carbon film, the same measurement was performed for a fluorescent lamp manufactured using a hollow electrode without a carbon film.

  The measurement results are shown in Table 1.

  From Table 1, it is understood that the lamp characteristics are improved in the fluorescent lamp using the hollow cathode (carbon film is formed only on the inner surface of the cylinder) manufactured using the jig of the present invention. For example, in terms of input power, there is an improvement effect of 15% or more.

  As described above, according to the present invention, it is possible to further promote downsizing, high luminance, and low power consumption of a fluorescent lamp and achieve further downsizing of a liquid crystal display device. Therefore, the present invention contributes to energy saving and environmental protection, and has great industrial applicability.

It is a figure which shows the manufacturing process of the conventional hollow cathode for fluorescent lamps. It is a figure which shows the manufacturing process of the hollow cathode for fluorescent lamps which concerns on this invention. It is a figure which shows the one aspect | mode of the manufacturing jig of this invention. It is a figure which shows another aspect of the jig for manufacture of this invention. (A) shows the aspect which attached the side mask member, (b) shows the aspect which attached another side mask member. It is a figure which shows the measurement aspect of the performance of a fluorescent lamp.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a Cylindrical member 1b Cylinder 2, 2b Electrode terminal 2a Terminal member 3 Lead wire 4 Glass bead 5 Rectangular plate-shaped body 6 Member accommodation hole 7 Plasma vapor deposition apparatus 8 Hollow cathode 9 Glass tube 10 Fluorescent lamp 11 Measurement glass tube 12 Side surface Mask member 13 Circular hole R Radius of curvature L Long side length W Short side length T Thickness d Inner diameter of cylinder φ Diameter of circular hole

Claims (9)

A jig used for manufacturing a hollow cathode provided with a connection terminal on the outer bottom of the cylinder, and provided with a deposited carbon film on the inner surface of the cylinder,
(I) a conductive rectangular plate formed by arc-shaped at the upper end of the short side,
(Ii) Along the long side surface of the rectangular plate-shaped body,
(Ii-1) open on the side of the long side, and
(Ii-2) Member housing that accommodates a cylindrical hollow cathode member with one end closed or a hollow cathode member having a connection terminal on the outer bottom of a cylinder with one end closed in a contact state perpendicular to the long side surface A jig for manufacturing a hollow cathode, wherein holes are formed.   The rectangular plate-like body has a melting point of 800 ° C. or higher and the same metal material as the hollow cathode member, a metal material having a thermal expansion coefficient substantially the same as that of the hollow cathode member, and smaller than the thermal expansion coefficient of the hollow cathode member The jig for manufacturing a hollow cathode according to claim 1, wherein the jig is made of a metal material having a coefficient of thermal expansion.   The rectangular plate-shaped body is a conductive ceramic material having a thermal expansion coefficient substantially the same as that of the hollow cathode member, or a conductive ceramic material having a thermal expansion coefficient smaller than that of the hollow cathode member. It is comprised, The jig for manufacture of the hollow cathode of Claim 1 characterized by the above-mentioned.   The said member accommodation hole is arrange | positioned in a line along the long side surface of the said rectangular plate-shaped object, The manufacturing process of the hollow cathode of any one of Claims 1-3 characterized by the above-mentioned. Ingredients.   4. The hollow cathode according to claim 1, wherein the member accommodation holes are arranged in a plurality of rows in the vertical direction along the long side surface of the rectangular plate-like body. Manufacturing jig.   6. A side mask member having a circular hole processed so as to cover an end of a cylinder whose one end is closed is attached to a long side surface of the rectangular plate-like body. A jig for producing a hollow electrode as described in 1. A method for producing a hollow cathode using the hollow cathode production jig according to any one of claims 1 to 6,
(I) A cylindrical hollow cathode member with one end closed, or a hollow cathode member having a connection terminal on the outer bottom of the cylinder with one end closed, is mounted in the member receiving hole of the manufacturing jig,
(Ii) A manufacturing jig equipped with a hollow cathode member is placed on the electrode on the anode side of the plasma deposition apparatus,
(Iii) forming a plasma atmosphere containing carbon radicals around the manufacturing jig, and forming a carbon film only on the inner surface of the hollow cathode member cylinder;
A method for producing a hollow cathode, comprising:   The hollow electrode manufacturing method according to claim 7, wherein the hollow cathode member cylinder is made of any one of Ni, Nb, Mo, Fe, and alloys thereof.   The method for producing a hollow cathode according to claim 7 or 8, wherein the carbon film is a carbon film having a nanostructure.

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