JPH08273625A - Discharge lamp for instrumental pointer - Google Patents

Abstract

PURPOSE: To prevent crack formation due to unevenness of thickness and improve reliability by producing an inner electrode connecting terminal from a metal cap and an almost cylindrical outer electrode having a slit in an axial direction from a metal plate. CONSTITUTION: An inner electrode 3 is electrically connected with an inner electrode connecting terminal 4 having a bottom closed cylindrical- or a bottom closed square column-like shape and made of a metal material by covering a lead wire 3a of the inner electrode 3 installed only one end part of a tubular bulb 2 with the terminal 4. An outer electrode 5 is composed by setting a metal plate, which is shaped into an almost cylindrical shape with an inner diameter approximately equal to or smaller than the outer diameter of the tubular bulb 2 and has a slit to become a light emitting window 5a in the axial direction, in the outer surface of the tubular bulb 2 and the outer surface of the outer electrode 5 is made to be an outer electrode connecting terminal 5a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold-cathode discharge lamp, and more particularly, it is provided with an internal electrode only at one end of a tubular bulb and the other electrode as an external electrode, such as a pointer for an automobile instrument. The present invention relates to a discharge lamp for a meter pointer, which is configured to be suitable for use.

[0002]

2. Description of the Related Art As a structure of a conventional discharge lamp of this type,
There is one disclosed in Japanese Utility Model Publication No. 4-27086,
One end of the tubular valve on the side where the internal electrode is sealed is provided with one power receiving terminal made of a conductive paste that is conductive with the internal electrode. An outer electrode is formed on the outer surface of the tubular valve along the axis by carbon phenol.

Further, the other side of the external electrode is provided with a conductive paste on the side close to the internal electrode, and a slit-shaped light emitting window is provided along the axis on the outer surface of the tubular bulb. A light-shielding film covers the other one of the power receiving terminals.

[0004]

However, in the above-described conventional discharge lamp, first, a conductive paste is applied to one end of the tubular bulb to form one power receiving terminal, and the tubular bulb is directly Since the power is supplied by sandwiching it, it is necessary to increase the strength by thickening this portion, and unevenness in the thickness causes distortion and tends to cause cracks, which causes leakage failure in the discharge lamp. Cause problems.

Secondly, since a conductive film is formed on the end portion of the tubular valve with a conductive paste such as silver epoxy, the connection with the lead wire of the internal electrode is ensured and the terminal is used as a terminal. In order to guarantee the strength of the above, a considerable film thickness is required, and a large amount of expensive silver epoxy is used, resulting in a high cost.

[0006] Thirdly, it is necessary to perform three coating steps on the outer surface of the tubular valve, such as carbon phenol as an external electrode, a conductive paste as the other power receiving terminal, and an opaque paint as a light-shielding film. A masking process for the light emitting window and the other power receiving terminal is also required at the time of coating the light shielding film, which complicates the work and raises a problem that the cost becomes high in this respect as well.

Fourthly, since the light emitting window is formed in the painting process, the method of forming the light emitting window is to use a masking tape, and the edge of the light emitting window is caused by baldness or rust of the paint when the masking tape is peeled off. However, the accuracy of the product will be impaired when it is used as a guide, and the product properties will be significantly impaired. There is.

[0008]

As a concrete means for solving the above-mentioned conventional problems, the present invention provides an internal electrode at one end of a tubular valve, and an external electrode on the outer surface of the tubular valve. In the instrument pointer discharge lamp, wherein the internal electrode and the external electrode are respectively provided with connection terminals, the tubular electrode is electrically connected to the internal electrode at the end on the side where the internal electrode is provided. To form an internal electrode connection terminal with a metal cap attached thereto, the outer surface of the tubular valve having an inner diameter substantially equal to or smaller than the outer diameter of the tubular valve and having a slit in the axial direction. A metal plate formed in a cylindrical shape is attached to form an external electrode,
An object of the present invention is to provide a discharge lamp for instrument pointer, wherein the slit of the metal plate serves as a light emitting window and the outer surface of the metal plate serves as an external electrode connection terminal.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described in detail based on an embodiment shown in the drawings. Reference numeral 1 in FIGS. 1 and 2 is a meter pointer discharge lamp according to the present invention. This meter pointer discharge lamp 1 has an internal electrode 3 having a lead wire 3a only at one end of a tubular bulb 2. Is provided with the tubular valve 2
Similar to the conventional example, an external electrode is provided on the outer surface of each of the electrodes and a connection terminal is provided on each of the electrodes.

Here, in the present invention, the internal electrode connecting terminal 4 provided for the internal electrode 3 is formed as a cap having a cylindrical shape with a bottom or a rectangular cylinder with a bottom, at this time. The inner electrode connection terminal 4 has an inner diameter appropriately larger than the outer diameter of one end of the tubular valve 2, and the one end of the tubular valve 2, that is, the inner electrode 3 is provided. It is attached to the end on the open side and fixed by an appropriate means such as an adhesive.

The cross section of the internal electrode connection terminal 4 orthogonal to the axis of the tubular valve 2 may be circular, but may be, for example, a square in which the outer diameter of the tubular valve 2 is inscribed. It may be formed in a shape that can easily be matched with the other party when it is assembled into.

At this time, a lead wire hole 4a is provided at the bottom of the internal electrode connecting terminal 4, and the lead wire 3a is provided when the internal electrode connecting terminal 4 is attached to one end of the tubular valve 2. It is supposed that they are penetrated and soldered or the like to be electrically connected to the internal electrodes 3.

Further, in the present invention, the external electrode 5 is formed of a metal plate formed into a substantially cylindrical shape having an inner diameter equal to or smaller than the outer diameter of the tubular valve 2. When the outer electrode 5 is attached to the outer diameter of the tubular bulb 2, a slit having a specified width is formed along the axial direction of the tubular bulb 2, and the slit serves as the light emitting window 5a. .

Here, when the inner diameter of the outer electrode 5 is made smaller than the outer diameter of the tubular valve 2, the metal plate is preferably a member having high elasticity such as phosphor bronze. By having it, the tubular valve 2 is inserted in the axial direction to be locked at a predetermined position, and the subsequent fixing work of the tubular valve 2 and the external electrode 5 is facilitated.

The outer electrode 5 attached to the tubular valve 2 is covered with a resin cap 6 made of a resin or the like from the end of the tubular valve 2 opposite to the side on which the inner electrode 3 is provided. It is worn and fixed. Further, the end portion of the external electrode 5 opposite to the resin cap 6 is fixed by a heat shrinkable tube 7 or the like if necessary. An adhesive may be used together in fixing any of the above-mentioned portions.

As described above, since the external electrode 5 is formed of the metal plate according to the present invention, the external surface of the external electrode 5 can be used as the external electrode connecting terminal 5b in any part. Therefore, when the outer surface of the external electrode 5 is required to be colored as an instrument pointer, the external electrode connecting terminal 5
It suffices if coloring is applied by painting, plating, etc., except for the portion b. Also, if white coating is applied to the inner diameter side, the reflection efficiency is improved.

Here, as a result of the trial manufacture by the inventor of the present invention, there is a case where the tubular bulb 2 is slightly curved in the axial direction in the process of forming the discharge lamp. In this case, it has been found that when the external electrode 5 is applied, a part that comes into close contact with the external electrode 5 and a part that creates a gap are generated, and the light emission efficiency is reduced in the part where the gap is created to cause light unevenness.

Therefore, the present invention also provides a countermeasure against the above-mentioned light unevenness, and the temperature at which the tubular valve 2 is appropriately softened (400 to 400) while the external electrode 5 is attached to the tubular valve 2. By performing the heat treatment at 500 ° C.), the axial curvature of the tubular bulb 2 is corrected, the tubular bulb 2 and the external electrode 5 are brought into close contact with each other, and the occurrence of the light unevenness is eliminated.

Next, the operation and effect of the instrument pointer discharge lamp 1 of the present invention having the above-mentioned configuration will be described. First, a metal cap is attached to one end of the tubular valve 2 to form the internal electrode connecting terminal 4, so that when the internal electrode connecting terminal 4 is sandwiched to supply power to the internal electrode 3, Since this internal electrode connection terminal 4 has sufficient strength, it is not necessary to secure strength by making a part of the tubular valve 2 thick, and the tubular valve 2 has a uniform thickness to avoid cracking. To do.

Further, since the internal electrode connecting terminal 4 is metallized, the internal electrode 3 (lead wire 3a) and the internal electrode connecting terminal 4 can be connected by a cheap, simple and reliable means such as soldering. Connection becomes possible and productivity, cost, and reliability can be improved in all aspects.

Furthermore, since the external electrode 5 is formed of a metal plate, the external electrode 5 formed in advance is inserted into the tubular valve 2 from the axial direction and fixed by a resin cap 6 or the like, so that the external electrode 5 is formed. The light emitting window 5a is obtained at a predetermined position, and at the same time, the outer surface of the external electrode 5 becomes the external electrode connecting terminal 5b, and the number of steps for obtaining these is reduced.

In addition, since the external electrode 5 is formed of a metal plate, it is formed by mechanical processing such as pressing, and the light emitting window 5a is also formed by mechanical processing. Therefore, the accuracy such as the linearity of the edge is improved, and the aesthetic appearance when used as a pointer is improved.

[0023]

As described above, according to the present invention, there is provided a discharge lamp for an instrument pointer, which includes an internal electrode connecting terminal formed of a metal cap and an external electrode formed of a metal plate and having a slit in the axial direction and having a substantially cylindrical shape. By doing so, firstly, it is possible to form the tubular valve with a uniform thickness by eliminating the need for strength on the tubular valve side as the internal electrode connection terminal has sufficient strength. It is assumed that the generation of cracks due to non-uniformity does not occur, and an excellent effect is obtained in improving the reliability of the instrument pointer discharge lamp.

Secondly, with the above construction, the electrical connection between the internal electrodes and the internal electrode connection terminals can be made by inexpensive, simple and reliable soldering, and the complicated, expensive and uncertain silver epoxy, etc. The formation of a conductive film is unnecessary, and excellent effects can be obtained in cost reduction and reliability improvement.

Thirdly, since the external electrode is formed of a metal plate, the external electrode formed in advance is axially inserted and fixed to the tubular bulb so that the external electrode and the light emitting window are at predetermined positions. At the same time, the outer surface of the external electrode serves as an external electrode connection terminal, which simplifies the work and reduces the number of steps, and also in this respect, the excellent effect of cost reduction can be achieved.

Fourthly, since the external electrodes are made of a metal plate, mechanical processing such as press working is possible in forming the external electrodes, and the light emitting window is also formed by mechanical working. It is possible to improve the accuracy such as the linearity of the edge, improve the appearance when used as a pointer, and have an excellent effect on improving the productability. Therefore, in the present invention, the discharge lamp for a meter pointer has improved reliability, cost reduction, and improved commercialability, and has extremely excellent effects in many aspects.

Further, the heat treatment is performed in a state where the outer diameter of the tubular valve is adhered to the outer diameter of the tubular valve, so that the adhesion between the tubular valve and the outer electrode is improved, and the gap between the tubular valve and the outer electrode is prevented. It also has an excellent effect of preventing the occurrence of light unevenness caused by the uniformity and further improving the commercialability of the instrument pointer discharge lamp.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a discharge lamp for instrument pointer according to the present invention in a partially disassembled state.

FIG. 2 is a sectional view taken along line AA of FIG.

[Explanation of symbols]

 1 ... Discharge lamp for instrument pointer 2 ... Tubular bulb 3 ... Internal electrode 3a ... Lead wire 4 ... Internal electrode connection terminal 5 ... External electrode 5a ... Emitting window 5b ... External electrode connection terminal 6 ... Resin cap 7 ... Heat shrink tube

Claims (2)

[Claims] 1. An instrument pointer comprising an internal electrode provided on one end of a tubular valve, an external electrode provided on an outer surface of the tubular valve, and a connection terminal provided on each of the internal electrode and the external electrode. In the electric discharge lamp, an end portion of the tubular bulb on the side where the internal electrode is provided is electrically connected to the internal electrode and is covered with a metal cap to form an internal electrode connection terminal. On the outer surface, a metal plate formed into a substantially cylindrical shape having an inner diameter substantially equal to or smaller than the outer diameter of the tubular valve and having a slit in the axial direction is applied to form an external electrode. A discharge lamp for instrument pointer, wherein the slit serves as a light emitting window and the outer surface of the metal plate serves as an external electrode connecting terminal. 2. The instrument pointer according to claim 1, wherein the outer diameter of the tubular valve is covered with the outer electrode, and heat treatment is performed to increase the degree of adhesion between the outer electrode and the outer electrode. Discharge lamp.