JPS59175551A - Discharge lamp - Google Patents

Abstract

PURPOSE:To obtain a discharge lamp that can prevent the higher temperature rise of an electrode than it requires, improve starting, and maintain stable performance by locating a resistor heating element on the external surface of a bulb at the inner side along the axial direction rather than between electrodes. CONSTITUTION:When a resistor heating element 7 is applied on the external surface of a bulb 1, this resistor heating element 7 is located at the inner side along the axial direction rather than between electrodes 2 and 2. As a result, the thermal effect of the resistor heating element 7 on the electrodes 2 and 2 can be reduced and the higher temperature rise of the electrodes 2 and 2 that reach high temperatures during discharge and their vicinity that they require can be prevented. For this reason, the temperature distribution along the axial direction of the bulb 1 can be set to the temperature that satisfies start almost evenly and the starting at low temperatures is improved. Since impure gas is not emitted from the electrodes 2 and 2, stable lamp performance can be maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a discharge lamp in which a mesh-like resistance heating element is attached to the outer peripheral surface of the bulb.

[Technical background of the invention and its problems]

Recently, the instrument display panels of automobiles and other vehicles are changing to digital displays, and cold cathode discharge lamps are used as the light source for the digital display panels (2). Since it is covered with leather, it has the characteristic of immediately starting to discharge and emit light, making it extremely suitable as a light source for the above-mentioned instrument display panels and the like.

However, when automobiles are used in cold regions or in winter, the temperature of the discharge lamp itself is low, so the mercury vapor pressure inside the bulb during startup is low, and for this reason, the original characteristics are low. There was a problem in which starting performance was impaired to some extent, and in the worst case, the engine did not start.

As a countermeasure for this, recently, a mesh-like thin film resistance heating element is attached to the outer circumferential surface of the bulb along its entire length, and this resistance heating element completely heats the bulb, thereby reducing the mercury vapor pressure inside the bulb. Discharge lamps with improved startability have been developed.

However, in this case, even with the above-mentioned cold cathode type discharge lamp, ions collide with the electrodes during discharge, so the temperature of the ζ2 electrode and its vicinity is higher than that of the bulb, as shown by temperature distribution line A in Figure 4. It tends to be higher than the other parts. When the bulb of such a discharge lamp is heated with a resistance heating element attached over the entire length of the bulb as described above, the middle part of the bulb is sufficiently started, as shown by temperature distribution line B in Figure 4. However, on the other hand, since the electrode part, which is already in a high temperature state, is further heated by the resistance heating element,
The temperature of this electrode portion becomes too high. As a result, impure gas is released from the electrodes and the discharge becomes unstable.

There are problems with the lamp performance such as premature bulb failure (1), which causes a blackening phenomenon and a decrease in brightness.

[Purpose of the invention]

The present invention was made based on these circumstances, and
The purpose of the present invention is to provide a discharge lamp which can prevent an excessive rise in temperature of an electrode part, improve startability, and maintain all five stable performances.

[Summary of the invention]

That is, the present invention achieves all of the above objects.

Attach a resistance heating element to the outer circumferential surface of the bulb (-).

A feature of the present invention is that this resistance heating element is located inside the tube axis direction rather than between the electrodes.

[Embodiments of the invention]

The present invention will be explained below based on an embodiment shown in the drawings.

Figures 1 and 2 show a cold cathode type discharge lamp.
is the straight pipe type valve. Both ends of the bulb 1 are connected to electrodes 2,
2, and from the stems 3, 3 lead wires 4, 4 connected to the electrodes 2, 2 are sealed.
has been derived. Also, 1 yen of valve has 5.5 f exhaust pipe.
An inert gas mainly composed of argon or the like and mercury are sealed through the bulb 1, and a phosphor coating 6 is coated on the inner surface of the bulb 1.

A resistance heating element 7 for heating the bulb 1 is attached to the outer circumferential surface of the bulb 1.The resistance heating element 7 is made of a metal material such as stainless steel, and the entire surface The resistance heating element 7 is formed of a thin film and a mesh shape.The resistance heating element 7 is attached to the outer circumferential surface of the bulb 1 along the tube axis direction, and extends over half the circumference of the bulb 1. The unmeshed lead wire connection parts 8, 8 provided at both ends are located on the inner side along the tube axis direction than the electrodes 2, 2. Therefore, the resistance heating element 7 avoids the electrodes 2, 2 at both ends. The lead wire connection portions 8, 8 (- are electrically connected to the power supply lead wires 9, 9, and the lead wire 999 is attached to the outer peripheral surface of the bulb 1.
The resistive heating element 7 generates heat when energized, thereby heating the bulb 1.

In the case of this embodiment, the outer peripheral surface of the bulb 1 is covered with a transparent heat-shrinkable tube 10, and the resistance heating element 7 is held on the outer peripheral surface of the bulb 1 by this heat-shrinkable tube 10. ing.

According to such a configuration, when attaching the resistance heating element 7 to the outer peripheral surface of the bulb 1, the resistance heating element 7 is attached to the electrode 2,
Since it is located inside along the pipe axis direction than between the two spaces,
'The thermal influence of the resistive heating element 7 on the electrodes 2, 2 is reduced, and the temperature increase of the electrodes 2, 2 and their vicinity, which become high during discharge, can be prevented from increasing beyond that required. Therefore, as shown by the fourth factor temperature distribution line C, the temperature distribution along the tube axis direction of the valve 1 can be made uniform to a temperature sufficient for starting (''-- almost uniformly, and good starting performance at low temperatures can be achieved. Of course, electrode 2,
Since there is no possibility of impurity gas being released from the bulb 2, abnormal discharge phenomena and early blackening of the bulb 1 (-) can be prevented from reducing the brightness.

It has the advantage of maintaining stable lamp performance.

Note that the present invention (-) the discharge lamp is of a cold cathode type (-)
For example, it may be a hot cathode type discharge lamp,
Furthermore, the material of the resistance heating element and the means for attaching it to the bulb are not specified in the above embodiments.

Alternatively, a resistive heating element may be applied over the entire circumference of the bulb.

〔Effect of the invention〕

According to the present invention described in detail above, the resistance heating elements for heating the bulb are provided in two positions in the tube axis direction (- along the inner side) than the electrodes at both ends of the bulb. As a result, it is possible to ensure good starting performance at low temperatures, and there is no risk of impurity gas being released from the electrodes, so brightness due to abnormal discharge phenomena or early blackening of the bulb can be prevented. This has the advantage that it is possible to prevent a decrease in lamp performance and maintain stable lamp performance from the initial stage to the final stage of one lighting operation.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, with the first figure being a perspective view and the second figure being a perspective view.
The figure is a side view, Figure 3 is a sectional view along the neutralization line - ■ in Figure 2,
FIG. 4 is a characteristic diagram showing the temperature distribution of the bulb. 1... Bulb, 2... Electrode, 7... Resistance heating element.

Claims (1)

[Claims] Both ends of the bulb; - sealing the electrodes; A resistance heating element for heating the outer circumferential surface of this bulb is attached along the tube axis direction (-), and this resistance heating element is located inside along the tube axis direction than between the electrodes. Characteristic discharge lamp.