JPH05182633A - Fluorescent lamp - Google Patents

Abstract

(57) [Summary] [Purpose] The sleeve that houses the coil is made smaller and thinner, and blackening is suppressed. [Structure] Coil 4 whose surface is coated with thermionic emission material
Is a fluorescent lamp having an electrode housed in a metal sleeve, and the sleeve is composed of a coil sleeve 5 formed of a metal wire having a low sputtering rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small fluorescent lamp used as a backlight of a liquid crystal display or the like.

[0002]

2. Description of the Related Art With the progress of book-type personal computers, word processors, and OA equipment, backlights of liquid crystal displays and fluorescent lamps incorporated as light sources are becoming smaller, more efficient, and more efficient. It is being pushed forward. Therefore, recently, a small fluorescent lamp using a so-called hollow electrode is attracting attention as having higher efficiency and longer life than conventional hot cathode fluorescent lamps or cold cathode fluorescent lamps. Has been put to practical use to date. As a conventional technique for this type of compact fluorescent lamp, for example, Japanese Patent Laid-Open No. 2-1
A typical example is the fluorescent lamp described in Japanese Patent No. 81352.

In this fluorescent lamp, as shown in FIG. 13, hollow type heat electrodes 31 and 32 are enclosed at both ends of a straight tubular discharge vessel 30, and one lead is provided to each of the heat electrodes 31 and 32. By connecting the wires 33 and 34, the hot electrode has a structure as shown in FIG. That is, iron-
A double coil 36 coated with a thermoelectron emitting substance is inserted inside a sleeve 35 made of a nickel alloy, and one end of this double coil 36 is connected and fixed to the sleeve 35 at a crushed portion 37. ing.

When this fluorescent lamp is used for a liquid crystal backlight, a tube having a diameter of about 3 to 6 mm is generally used. Therefore, regarding the sleeve 35,
It is desirable to be as small and thin as possible. As a starting method, generally, a method of transferring glow arc at the time of starting without preheating is adopted. For this reason,
In order to reduce the damage applied to the electrode during the starting period, it is desirable that the sleeve 35 be as small and thin as possible, and that the physical properties of the material be particularly low in thermal conductivity and sputtering rate. Further, since the double coil 36 may come into contact with the sleeve 35 during lighting, it is desirable that the thermal conductivity of the sleeve 35 is small also from this viewpoint.

[0005]

However, heretofore, the emphasis has been placed exclusively on forming the sleeve into a small size and thin wall, and a material such as a nickel alloy, which is easy to form into a thin wall as much as possible, has been used. There is. It has been pointed out that this type of material has a high sputter rate, and thus tends to turn black when blinking. By the way, an alkaline earth oxide is often used as the thermoelectron emitting material applied to the coil, and in general, this alkaline earth oxide easily reacts with water in the atmosphere to easily become a hydroxide. For this reason, when manufacturing this type of fluorescent lamp, thermionic emission material is first applied to the coil in the form of carbonate, and the electrode is heated by a high-frequency induction coil or a heater in the step of exhausting the glass tube. Decomposes salt into oxide. Heretofore, there has been a difficulty in disassembling a coil coated with a carbonate thermoelectron emitting material by thermally contacting the sleeve. In order to promote this, when using a double coil or a triple coil as the coil, there is a problem that heat escapes due to conduction from the coil during lighting. The wire whose diameter is thin is used. However, mechanical strength is weak in such a double coil or triple coil of tungsten thin wire, and there are problems in the application process of thermionic emission material or in the connection between the sleeve and the inner lead, and the coil breaks due to frequent blinking. It has been pointed out that it is easy and that it is easily dropped from the sleeve. On the other hand, it has been pointed out that both the sleeve and the coil are very small parts, and the efficiency of fine work such as positioning and welding at the time of joining with the inner lead is poor. Therefore, the present invention aims to solve the above-mentioned problems of the prior art, suppress blackening, improve durability, and provide a fluorescent lamp that facilitates assembly in a manufacturing process. And

[0006]

In order to achieve the above object, the present invention comprises a coil sleeve formed of a metal wire having a low sputtering rate.

Further, in order to achieve the above-mentioned object, the present invention is constructed so as to accommodate the coil eccentrically with respect to the axis of the coil sleeve.

Further, in order to achieve the above object, according to the present invention, a coil sleeve extending to the inner lead side is partially provided with a different diameter coil portion having a small outer diameter and a small inner diameter, and the inner diameter portion of the different diameter coil portion is provided. It is configured by inserting the leg portion of the coil into.

Further, in order to achieve the above object, the present invention is configured such that the different diameter coil portion is screwed and joined to the coil sleeve as a separate member from the coil sleeve.

[0010]

According to the present invention, the coil sleeve 5 can be formed as small and thin as possible by forming the coil sleeve 5 with the winding coil. Moreover, since there is contact resistance between the windings that are in contact with each other, the thermal resistance is greater than when a simple cylindrical sleeve is molded with the same material as in the past, and the coil heating time immediately after lighting is increased. Can be shortened to prevent damage to the electrode during glow discharge. Furthermore, since a material having a low sputtering rate such as tungsten is applied to the material of the coil sleeve, blackening of the tube wall is suppressed.

Further, the coil sleeve is arranged so as to be eccentric from the axis of the coil sleeve so that the coil is housed, and the thermoelectron emitting substance applied to the surface of the coil is heated from the oxide by heating from the carbonate. In the step of decomposing into, the temperature of the coil surface easily rises, the activation of the thermoelectron emitting substance is promoted, and the decomposition is surely carried out.

Further, a coil sleeve extending outwardly on the inner lead side is provided with a part having a different diameter coil part having a small outer diameter and a small inner diameter, and the leg part of the coil is inserted into the inner diameter part of the different diameter coil part. By fitting the different diameter coil portion of the outer extension portion of the coil sleeve onto the inner lead when assembling the electrode, and then inserting the leg portion of the coil as a guide using the different diameter coil portion, It facilitates the positioning of very small parts.

Furthermore, the coil accommodated in the hollow portion of the coil sleeve is configured such that the coil having the different diameter is screwed and joined to the coil sleeve as a separate member from the coil sleeve. Positioning is performed by abutting the mating end. Then, the leg portions of the coil and the inner leads are fixed by caulking the different diameter coil portions. Therefore, in the process of attaching the assembled electrode to both ends of the glass tube and then heating with a high frequency induction coil to decompose the thermionic emission material from carbonate to oxide, the coil has a cooling effect from the inner lead side. Since it is in a position where it is difficult to receive it, the temperature is sufficiently raised to activate the thermionic emission material,
Disassembly is efficient and reliable.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the fluorescent lamp according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a vertical cross-sectional view of the entire fluorescent lamp. A hollow tubular hot cathode, the details of which will be described later, is formed at both ends of a glass tube 1 having a straight tube-shaped inner peripheral surface coated with a phosphor. Electrode 2 as
3 is attached. In this case, Ar gas is sealed inside the glass tube 1. In addition,
In this embodiment, the outer diameter of the glass tube 1 is 4 mm, the electrodes 2, 3 are
The distance between them is 20 to 200 mm, which is the specification of a small fluorescent lamp used as a backlight of a liquid crystal display. Next, FIG. 2 shows the structure of the electrode 2 in detail, and has a structure in which a coil 4 having a surface coated with a thermoelectron emitting substance is housed in a coil sleeve 5. The leg portion 4a of the coil 4 and the lead portion 5a of the coil sleeve 5 are joined to the inner lead 6 by spot welding.

In this embodiment, the coil 4 is a double coil, as shown in FIG. The specifications and dimensions are shown in Table 1. The thermionic emission materials applied to this coil are Ba, Sr, Ca, and Ba.
It may be -MO (M; W, Ta, Nb, V, Ti, Zr), an oxide of a rare earth element, or a boride. The coil 4
With regard to the above, a single coil or a triple coil can be configured depending on the application of the fluorescent lamp.

On the other hand, regarding the coil sleeve 5, in this embodiment, the wire diameter of the winding having the specifications and dimensions shown in Table 2 is 0.1.
A tightly wound coil made of an alloy mainly composed of 5 mm of tungsten is used. Here, the closely wound coil is
In FIG. 4, when the distance between the windings adjacent to the coil body is l and the diameter of the winding is d, the coil pitch P
(%)But, That is, a coil in which l = d. As the material of such a coil sleeve 5, the same effect can be obtained by using an alloy mainly composed of tantalum, which similarly has a small sputtering rate, in addition to tungsten. Table 1 Specifications and dimensions of double coil FD 3MG (0.032mm) MD1 0.1mm MD2 0.5mm CL 2.0mm TT 8 Next, regarding the operation of the embodiment configured as described above,
explain. The coil sleeve 5 is composed of a close contact coil made of a tungsten alloy or the like as a sleeve. Therefore, the coil sleeve 5 can be formed as small and thin as possible by using the winding wire having a small wire diameter. Moreover, since the coil sleeve 5 is a tightly wound coil, there is a contact resistance between the windings that come into contact with each other, so that compared to the case where a simple cylindrical sleeve is formed of the same material as in the conventional case, The thermal resistance is increased (the thermal conductivity is reduced). Therefore, it is possible to shorten the temperature rising time of the coil 4 immediately after lighting and suppress the damage to the electrodes during glow discharge. Further, even when the coil 4 accommodated may come into contact with the coil sleeve 5 during lighting, the heat of the coil 4 is less likely to escape through the coil sleeve 5 due to the decrease in the thermal conductivity described above, and the stability is stable. Spots can be formed. Further, since a material having a low sputtering rate such as tungsten is applied to the material of the coil sleeve 5, it is effective in suppressing the blackening of the tube wall. In fact, when the fluorescent lamp of the present embodiment is turned on with a lamp current of 10 to 20 mA, the arc transitions to the arc earlier than that of the conventional hollow type electrode in which the coil is housed in the conventional cylindrical sleeve, and it takes 5 seconds. It was confirmed that the occurrence of blackening of the tube wall was suppressed even when the blinking cycle of turning on the light for 5 seconds was repeated.

Next, an embodiment of the invention described in claim 4 will be described with reference to FIGS. The fluorescent lamp according to this embodiment is configured by providing an electrode 10 shown in FIG. 5 in place of the electrode of the first embodiment. In this embodiment, the coil 11 housed inside the coil sleeve 5 is
On the surface of (Ba, Sr, Ca) CO ₃ a trace amount of Z
A coil coated with a thermionic emission material added with rO ₂ is used, and this coil 11 is an axis 12 of the coil sleeve 5.
It is positioned at a position eccentric from. In this case, the leg 11a of the coil 11 and the lead 5a of the coil sleeve 5 are joined to the inner lead 6 by using the clamp member 14 so that the coil 11 is eccentric.
Regarding thermionic emission materials, (Ba, Sr, C
a) In addition to CO ₃ , BaO.CaO.Al ₂ O ₃ or a substance obtained by adding ZrO ₂ or Y ₂ O ₃ to these substances may be used.

As the coil 11, a tightly wound single coil having a total length of 2.5 mm, which is formed by winding a 14 MG tungsten wire around a mandrel having a diameter of 0.3 mm, is used.

However, according to this second embodiment, the coil 11 is eccentric to the coil sleeve 5 from its axis.
Are to be accommodated. For this reason, in the manufacture of the lamp, the coil 11 is heated by the high frequency induction coil.
In the step of decomposing the thermoelectron emitting substance applied to the surface of the carbon dioxide into an oxide, the temperature of the surface of the coil 11 easily rises, and the activation of the thermoelectron emitting substance is promoted to surely decompose it.

By using a single coil for the coil 11 as in this embodiment, a sufficient space is formed between the coil 11 and the coil sleeve 5. Therefore, since this space is filled with the negative glow, even if the wire diameter of the single coil is thickened, it is not difficult to raise the temperature after the start of lighting, and the wire diameter is thickened to enhance the mechanical strength. be able to. Therefore, with frequent blinking, coil 1
It is possible to improve such as preventing breakage of 1 and dropping off from the coil sleeve 5.

Next, FIGS. 6 and 7 are views showing a modified example of the above-mentioned second embodiment. Of these, in FIG. 6, a cylindrical sleeve 14 is used in place of the coil sleeve 5 using a close-wound coil, and the coil 11 is eccentrically housed to accommodate the coil 11 to form an electrode. FIG. 7 shows a modified example in which, when a glass tube of a fluorescent lamp having a flat cross section is adopted, the flat cylindrical sleeve 15 is eccentric to accommodate the glass tube and accommodates the coil 11 to form an electrode. In this case, both the cylindrical sleeve 14 and the flat cylindrical sleeve 15 are made of the same material as the coil sleeve 5 in the first embodiment.
A metal having a low sputter rate such as tungsten or tantalum is preferable from the viewpoint of preventing blackening, but other metals such as Mo, Ni,
Even if a material such as Fe or SUS is used, the same effect can be obtained in terms of accelerating the thermal decomposition of the thermionic emission material.

Next, an embodiment of the invention described in claim 6 will be described with reference to FIG. In this embodiment, the coil sleeve 16 accommodating the coil 4 is integrally provided with a different-diameter coil portion 17 having a reduced outer diameter and inner diameter at a part thereof which extends toward the inner lead 6 side.
The inner lead 6 and the leg portion 4a of the coil 4 are inserted into the inner diameter portion of the different diameter coil portion 17 of the coil sleeve 16, and these are joined by spot welding. The inner diameter of the different diameter coil portion 17 of the coil sleeve 16 is smaller than the outer diameter of the coil 4, so that when the leg portion 4a of the coil 4 is inserted into the different diameter coil portion 17, it functions as a stopper. Is becoming

According to the third embodiment constructed as described above, the coil 4 is fitted to the inner lead 6 when the different diameter coil portion 17 of the outer extending portion of the coil sleeve 16 is fitted onto the inner lead 6 when the electrode is assembled. By inserting the leg portion 4a of the different diameter coil portion 17 as a guide, it becomes easy to position these very small-sized components and it is possible to efficiently join them. In addition, although the coil 4 is configured as a double coil in this embodiment, the present invention is not limited to this, and a single coil or a triple coil may be used. Further, the coil sleeve 16 includes the different-diameter coil portion 17, and the winding method thereof is closely wound. However, the different-diameter coil portion 17 is not closely wound as shown in FIG. However, the same effect can be obtained in terms of the function of the leg portion 4a of the coil 4 as a guide. Next, an embodiment of the invention described in claim 7 will be described with reference to FIG. In this embodiment, a tightly wound different-diameter coil portion 17a, which is a separate member, is screwed and joined to the inner lead 6 side end of the coil sleeve 5 in which the coil 4 coated with the thermionic emission material is accommodated. The inner lead 6 and the leg portion 4a of the coil 4 are inserted into the hollow portion of the different diameter coil portion 17a, and the different diameter coil portion is fixed by caulking.

In the fourth embodiment constructed as described above,
Similar to the third embodiment, the different-diameter coil portion 17a functions as a guide for the leg portion 4a of the coil 4 during assembly, which facilitates the positioning of these small parts and improves the workability of joining. In addition to this, the coil 4 accommodated in the hollow portion of the coil sleeve 5 is regulated by the threaded end of the different-diameter coil portion 17a and is positioned at a position recessed inside. Therefore, after attaching the assembled electrode to both ends of the glass tube, in the process of heating with a high frequency induction coil to decompose the thermionic emission material from carbonate to oxide,
Since the coil 4 is located at a position where it is difficult to receive the cooling effect from the inner lead 6 side, there is an advantage that the temperature is sufficiently raised to activate and decompose the thermionic emission material efficiently and reliably.

FIG. 11 is a view showing a modification of the fourth embodiment, in which a non-contact winding type double coil is used for the different diameter coil portion 17a. Further, as shown in FIG. 12, a non-contact type coil in which a relatively thick wire 18 is spirally wound and a thinner wire 19 is spirally wound may be used as the different diameter coil portion 20. In this case, when the different-diameter coil portion 20 is screwed into the coil sleeve 5,
The wire 19 has a function of adjusting the degree of threaded joint.

[0026]

As is apparent from the above description, according to the present invention, since the coil sleeve formed by the winding is used for the sleeve in which the coil is accommodated, the sleeve is made as small and thin as possible. In addition to this, since a material having a low sputtering rate is used, blackening can be suppressed. In addition, since the coil is housed so as to be eccentric with respect to the axis of the coil sleeve, the temperature of the surface of the coil easily rises, and the activation of the thermoelectron emitting substance is promoted, so that the effect of sure decomposition is obtained. can get. Further, by providing a different diameter coil portion having a small outer diameter and inner diameter in a part of the coil sleeve extending to the inner lead side, and by configuring the coil leg portion to be inserted into the inner diameter portion of the different diameter coil portion, By inserting the leg portion of the coil by using this different diameter coil portion as a guide, it becomes easy to position these very small parts. Furthermore, since the different-diameter coil portion is screwed and joined to the coil sleeve as a separate member from the coil sleeve, the coil is regulated by the threaded end of the different-diameter coil portion and positioned at a position recessed inside. The coil is sufficiently heated at a position where it is difficult to receive the cooling effect from the inner lead side, and the activation and decomposition of the thermionic emission material are efficiently and reliably performed.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a fluorescent lamp according to the present invention.

FIG. 2 is a sectional view of electrodes of a fluorescent lamp according to an embodiment corresponding to the invention of claim 1.

3 is a cross-sectional view of a coil forming the electrode of FIG.

4 is a cross-sectional view of a coil sleeve that constitutes the electrode of FIG.

FIG. 5 is a sectional view of an electrode of a fluorescent lamp of an embodiment corresponding to the invention of claim 4.

6 is a cross-sectional view showing a modified example of the electrode of FIG.

FIG. 7 is a perspective view of another modification of the electrode of FIG.

FIG. 8 is a sectional view of an electrode of a fluorescent lamp of an embodiment corresponding to the invention of claim 6;

9 is a sectional view showing a coil of a modification of the electrode of FIG.

FIG. 10 is a sectional view of an electrode of a fluorescent lamp of an embodiment corresponding to the invention of claim 7.

11 is a cross-sectional view of a modified example of the electrode of FIG.

FIG. 12 is a cross-sectional view of another modification of the electrode of FIG.

FIG. 13 is a cross-sectional view of a conventional fluorescent lamp including a hollow electrode.

14 is a cross-sectional view of the electrode of FIG.

[Explanation of symbols]

 1 glass tube 2 electrode 3 electrode 4 coil 4a leg part 5 coil sleeve 5a lead part 6 inner lead

Claims (7)

[Claims] 1. A fluorescent lamp having an electrode in which a coil having a surface coated with a thermionic emission material is housed in a metal sleeve, wherein the sleeve comprises a coil sleeve formed of a metal winding having a low sputtering rate. A fluorescent lamp that is characterized by 2. The fluorescent lamp according to claim 1, wherein the coil sleeve is a tightly wound coil. 3. The fluorescent lamp according to claim 1, wherein the material of the coil sleeve is an alloy containing tungsten or tantalum as a main component. 4. A fluorescent lamp having an electrode in which a coil having a surface coated with a thermoelectron emitting substance is housed in a metal sleeve, wherein the coil is housed eccentrically with respect to the axis of the coil sleeve. And a fluorescent lamp. 5. The fluorescent lamp according to claim 4, wherein the sleeve is a coil sleeve made of a metal having a low sputtering rate, and the coil housed in the coil sleeve is a single coil. lamp. 6. A fluorescent lamp having an electrode in which a coil having a surface coated with a thermionic emission material is housed in a metal sleeve, and a coil sleeve extending to the inner lead side has a part having both an outer diameter and an inner diameter. A fluorescent lamp having a small-diameter different-diameter coil portion, and a leg portion of the coil being inserted into an inner diameter portion of the different-diameter coil portion. 7. The fluorescent lamp according to claim 6, wherein the different-diameter coil portion is screwed and joined to the coil sleeve as a member separate from the coil sleeve.