JPH03250556A - High-pressure discharge lamp - Google Patents

Abstract

PURPOSE: To manufacture a capacitor easily at a low cost and prolong the lifetime of a high pressure discharge lamp by accommodating a voltage- subordinate capacitor of an ignition circuit in an air-tight glass capsule filled with a gas and installing it in a lamp cap. CONSTITUTION: A discharge lamp 2 is structured so that a discharge vessel 3 for performing electric discharge between electrodes 4 and 5 through rigid conductors 40 and 50 is installed in an outer bulb 30 having a lamp cap 31 in which an ignition circuit 10 is accommodated. The circuit 10 comprises a fuse 7, voltage-subordinate capacitor 8 and stabilising subordinate resistance 9, and impresses ignition voltage pulses for starting on the electrodes 4 and 5 using a circuit including a stabilizing ballast 1. The lifetime of the capacitor 8 is prolonged by accommodating it a glass capsule having a radiations reflecting layer and filled with a gas such as a rare gas or nitrogen to suppress segregation or evaporation of the component(S) during the operation, and the production can be very simply carried out with high reliability using known techniques.

Description

[Detailed description of the invention]

[0001]

[Industrial application field]

The invention relates to a high-pressure discharge lamp comprising a discharge vessel accommodated in a space formed by an outer bulb with a lamp cap and comprising an ignition circuit with a voltage-dependent capacitor. [0002] [Prior Art] This type of discharge lamp is disclosed in German patent DE-C-3,330,
266. This known discharge lamp has a stabilizing ballast connected in series and is suitable for use with an AC power source, but a capacitor is placed inside the outer bulb to prevent part of the capacitor from evaporating and becoming weaker. A glass envelope is provided for this purpose. However, in practice this has proven to be a disadvantage. On the one hand, this means that manufacturing capacitors with such an envelope is extremely difficult, which makes them expensive. Moreover, on the other hand, the service life of known discharge lamps is very often shortened due to damage to the capacitor. [0003] However, it is technically very attractive to install an ignition circuit within a discharge lamp. This is due to the fact that the uses of discharge lamps will be greatly expanded. [0004]

[Disclosure of the invention]

The object of the present invention is to improve the above-mentioned drawbacks while the ignition circuit remains housed within the discharge lamp. [0005] In order to achieve the above-mentioned object, the present invention is characterized in that a voltage dependent capacitor is housed in an airtight glass capsule filled with gas and placed in a lamp cap. [0006] The present invention is extremely simple and reliable to produce because it houses the capacitor within a glass housing using techniques that have been known and suitable for many years, and therefore can be performed reliably over conventional radiation It has the advantage of being cheaper than electric lights. The gas pressure makes it possible to suppress dissociation or evaporation of the components forming the capacitor. The composition of this gas is such that it does not affect the components of the capacitor even under operating conditions of the discharge lamp. Gases suitable for this are, for example, noble gases, nitrogen, oxygen and sulfur hexafluoride. The gas may be filled with a single gas, or a combination of a plurality of gases may be used. [0007] Mounting the capacitor within the lamp cap also provides the additional advantage of allowing the capacitor to be located a relatively large distance away from the discharge vessel. This limits the heating of the capacitor to a constant level during operation of the discharge lamp. [0008] The use of a glass capsule provides the advantage that the discharge lamp of the present invention can be used in locations where corrosive atmospheres are present without any other special protective measures being taken. [0009] Further improvements are obtained by providing a radiation-reflecting layer in the airtight capsule. In other words, this simple but effective means makes it possible to considerably reduce the degree of heating of the capacitor during operation of the discharge lamp. The radiation reflecting layer may be provided either on the outside or inside of the capsule. [0010] Another embodiment of the invention connects a voltage dependent resistor in series with a capacitor. The advantage of this is, on the one hand, that by suitably selecting the current-voltage characteristic of the resistor, the instant of occurrence of the ignition voltage pulse can be advantageously selected. On the other hand, the level of the ignition voltage pulse generated can be limited by the resistance characteristics of the voltage-dependent resistor. [0011] It is advantageous to include a fuse in the ignition circuit. In this way, even under extremely unfavorable conditions, for example when a capacitor is short-circuited, overloading of the stabilizing ballast due to the flow of extremely high currents can be prevented by blowing out the fuse. [0012]

【Example】

The present invention will be explained below with reference to the drawings. [0013] In FIG. 1, a discharge lamp 2 according to the invention has a discharge vessel 3. The discharge vessel 3 is accommodated in the space formed by the outer bulb 30. The outer bulb 30 is provided with a lamp cap 31 . The discharge lamp 2 has an ignition circuit 10, shown in FIG. 2, housed in a lamp cap 31. The ignition circuit 10 has a voltage-dependent capacitor 8 . This voltage dependent capacitor 8 is mounted in a glass airtight container (capsule) 11 filled with gas. Electrodes 4 and 5 of the discharge lamp are attached to the discharge vessel 3, and a discharge occurs between these electrodes when the discharge lamp is in operation. The electrode 4 of the discharge lamp is connected to the lamp contact C of the lamp cap 31 through a rigid conductor 40 6
Similarly, the discharge lamp electrode 5 is connected to the lamp contact of the lamp cap 31 through a rigid conductor 50. [0014] The starting circuit 10 is further provided with a fuse 7 and a voltage dependent resistor 9, both of which are connected to the lamp cap. installed inside. [0015] In FIG. 2, the same parts as in FIG. 1 are indicated by the same numbers. In the figure, A and B are connection terminals connected to the AC main power supply. Connection terminal A connects to lamp contact C through stabilizing ballast 1.
It is connected to the. Connection terminal B is connected to a lamp contact. The ignition circuit 10 is composed of a circuit including a fuse 7, a voltage dependent capacitor 8, a stabilizing dependent resistor 9, and a circuit including a stabilizing ballast 1. A voltage pulse is generated, which voltage is applied between the electrodes 4, 5 of the discharge lamp. [0016] The discharge vessel 3 can be further provided with an external auxiliary electrode for ignition assistance. [0017]

[Brief explanation of drawings]

[Figure 1] FIG. 1 is a side view of the discharge lamp of the present invention.

FIG. 2 is a circuit diagram showing the electric circuit of the discharge lamp and ballast of FIG. 1. [0018]

[Explanation of symbols]

1 Stabilizing ballast 2 Discharge lamp 3 Discharge vessel 4.5 Electrode 7 Fuyuse 8 Voltage dependent capacitor 9 Voltage dependent resistance 10 Ignition (starting) circuit Airtight container (capsule) outer valve lamp cap 50 Rigid conductor B Connection terminal to AC D Lamp contact =320- 'I8 open +3-250556 (0)

[Document person] drawing

[Figure 1]

[Figure 2]

Claims (3)

[Claims] 1. A discharge vessel housed within a space formed by an outer bulb having a lamp cap;
A high-pressure discharge lamp comprising an ignition circuit having a voltage-dependent capacitor, characterized in that the voltage-dependent capacitor is housed in an airtight glass capsule filled with gas and disposed within a lamp cap. 2. The high pressure discharge lamp according to claim 1, wherein the glass capsule is provided with a radiation reflecting layer. 3. The high pressure discharge lamp according to claim 1, further comprising a voltage dependent resistor connected in series to the voltage dependent capacitor.