JP3589117B2 - lamp - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a lamp having a rod-shaped heating element, and more particularly, to a heater lamp using a carbon-based material as the heating element.
[0002]
[Prior art]
Lamps that emit a large amount of infrared light are widely used as heater lamps for heating, industrial applications such as heating and drying, etc., but conventional heater lamps are made of a coil made of tungsten along the tube axis of a tubular envelope. Generally, filaments were arranged. When energized, the coil filament generates heat. The heated tungsten coil filament emits a large amount of visible light, and the emissivity of infrared rays is about 30 to 40%. Therefore, the efficiency of a heater lamp using infrared rays is not always high.
[0003]
Further, a heater lamp using a coil coil of tungsten has a large inrush current through which a current larger than the rated current flows when it is turned on, and a protection circuit is required to deal with this. Furthermore, in order to hold the coil filament on the tube axis of the envelope, the coil filament is held by a plurality of supporters. However, there is a problem that the number of parts is large and the assembly is troublesome.
[0004]
For this reason, a heater lamp using a rod-shaped carbon-based material as a heating element has recently been receiving attention. A carbon-based material made of crystallized carbon such as graphite, amorphous carbon, or a mixture thereof has an infrared emissivity of about 80%, and emits infrared light more efficiently than tungsten, and thus is excellent as a heating element of a heater lamp. In addition, since the carbon-based material has a negative resistance-temperature characteristic, and the resistance value decreases as the temperature increases, the rush current at the time of lighting decreases. Since the rod-like carbon-based material can be disposed along the tube axis of the sealing body by holding both ends, there is an advantage that a plurality of supporters are unnecessary, the number of parts is small, and assembly is simple.
A lamp using a rod-like carbon-based material as a heating element is disclosed in, for example, Japanese Patent Application Laid-Open No. H11-54092.
[0005]
[Problems to be solved by the invention]
By the way, when a lamp having a rod-shaped heating element is turned on, the heating element thermally expands, and it is necessary to absorb this thermal expansion. FIG. 3 shows a conventional structure for absorbing thermal expansion of a rod-shaped heating element. A coil fixing portion 23b is formed at the tip of an internal lead rod 23 whose one end is welded to a molybdenum foil 21 embedded in the sealing portion 11 at the end of the sealing body 10, and the coil fixing portion 23b is a rod-shaped heating element 30. It is firmly fixed to the end by caulking. This is because, if the fixing is loose and the coil fixing portion 23b slides on the surface of the heating element 30, the surface of the heating element 30 made of a carbon-based material is shaved to cause poor electrical contact. The inner lead bar 23 is formed with a spring portion 23c formed by winding a wire for about three turns following the coil fixing portion 23b. When the heating element 30 thermally expands, the spring portion 23c contracts, thereby causing heat. Absorb swelling.
[0006]
Here, in order to improve the elasticity of the spring portion 23c, it is necessary to reduce the wire diameter of the internal lead bar 23 made of, for example, molybdenum wire to reduce the spring constant. When the wire diameter is small, the spring portion 23c of the internal lead bar 23 also generates a large amount of heat. When the spring 23c generates heat and becomes high temperature, the elasticity is lost and the thermal expansion absorbing function is not exhibited. On the other hand, if the wire diameter of the internal lead bar 23 is made large to make it difficult to generate heat, the spring constant is increased and the elasticity is reduced. When the thermal expansion absorbing function is lost, the connection portion by the coil fixing portion 23b is broken, and a contact failure occurs and the lamp does not light. Problems such as erosion of the body 10 occur.
[0007]
Therefore, an object of the present invention is to provide a lamp that can reliably absorb the thermal expansion of a rod-shaped heating element.
[0008]
[Means for Solving the Problems]
In order to achieve such an object, the present invention provides a pair of internal lead rods extending from the sealing portions at both ends of the sealing body into the sealing body at both ends of a rod-shaped heating element arranged along the pipe axis of the tubular sealing body. Is electrically connected, a conductive power supply pin is connected to the end of the heating element, and a cylindrical power supply section is formed at the tip of the internal lead rod, and this cylindrical power supply section is connected to the power supply pin. Slide fit freely.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. FIG. 1 shows one end of a lamp according to an embodiment of the present invention. In FIG. 1, sealing portions 11 are formed at both ends of a tubular sealing body 10 made of quartz glass. The outer diameter of the sealing body 10 is, for example, 10 mmφ. A molybdenum foil 21 is embedded in the sealing portion 11, and an external lead rod 22 whose one end is welded to the molybdenum foil 21 extends outside. Also, an internal lead bar 23, one end of which is welded to the molybdenum foil 21, extends inside the envelope 10. The internal lead rod 23 is made of a molybdenum rod, and a coil-shaped cylindrical power supply portion 23a in which the molybdenum rod is densely wound is formed at a tip end thereof. The cylindrical power supply portion 23a may be a pipe made of, for example, molybdenum welded to the tip of the internal lead rod 23.
[0010]
A rod-shaped heating element 30 is arranged along the tube axis of the envelope 10. The heating element 30 is formed by shaping a carbon-based substance made of crystallized carbon such as graphite, amorphous carbon, or a mixture thereof into a rod shape. A recess is formed at an end of the heating element 30, and a conductive power supply pin 24 made of, for example, molybdenum is press-fitted into the recess and connected thereto. The heating element 30 and the power supply pin 24 may be connected by a fixed coil 25 shown in FIG. The cylindrical power supply portion 23a of the internal lead bar 23 is slidably and electrically connected to the power supply pin 24. Specifically, the coil-shaped cylindrical power supply portion 23a is formed by densely winding a molybdenum rod around a round bar having the same outer diameter as the power supply pin 24. The inner diameter of the cylindrical power supply portion 23a is substantially the same, but the inner diameter of the cylindrical power supply portion 23a is somewhat large so that the cylindrical power supply portion 23a slides easily when fitted and does not impair conductivity.
A small amount of a halogen gas is sealed in the sealing body 10 together with an inert gas such as a rare gas or a nitrogen gas, and the halogen lamp has a rated power consumption of, for example, 200 W.
[0011]
FIG. 2 shows one end of a lamp according to another embodiment. In FIG. 2, a rod-shaped base 31 made of a heat-resistant non-conductive material, for example, alumina is arranged along the tube axis of the sealing body 10, and a conductive power supply pin 24 is provided at an end of the base 31. They are connected by a fixed coil 25. Then, carbon 32 is coated from the surface of the base 31 to the surface of the fixed coil 25 as indicated by a dotted line for convenience. That is, the heating element 30 is constituted by the heat-resistant non-conductive base 31 and the conductive carbon 32 coated on the surface thereof. The cylindrical power supply portion 23a of the internal lead rod 23 is slidably and conductively fitted to the power supply pin 24.
[0012]
In the embodiment shown in FIG. 1, the heating element 30 is formed by shaping a carbon-based material into a rod shape. However, since the carbon-based material has a low resistivity, in order to obtain a predetermined resistance value required for the lamp, It is necessary to make the carbon rod thin and long, but since the length is determined by the lamp specifications, it is necessary to make the carbon rod extremely thin in order to increase the resistance value of the heating element. Further, since the carbon-based material has inherently brittle properties and a small diameter, when a vibration or an impact is applied to the lamp, there is a problem that the carbon-based material serving as a heating element is broken and becomes unlit. However, when the heating element 30 is composed of the heat-resistant non-conductive base 31 and the carbon 32 coated on its surface, the base 31 is tough, so that the heating element 30 breaks even when vibration or impact is applied to the lamp. There is an advantage that it is difficult to do. The resistance value of the heating element 30 can be arbitrarily set by adjusting the thickness of the carbon 32.
[0013]
When the lamp shown in FIGS. 1 and 2 is energized, the heating element 30 generates heat. However, since the carbon-based material has a high infrared emissivity, infrared rays are efficiently emitted, and the inrush current at the time of lighting does not increase. Therefore, there is an advantage that a large protection circuit is not required. Then, the rod-shaped heating element 30 thermally expands with lighting, but the cylindrical power supply section 23a of the internal lead bar 23 is slidably fitted to the power supply pin 24 connected to the heating element 30. The power supply pin 24 slides in a conductive state in the cylindrical power supply portion 23a in accordance with the thermal expansion of the body 30, so that the thermal expansion of the heating element 30 can be reliably absorbed. In addition, since the power supply pin 24 is made of a conductor such as molybdenum, even if the slide is repeated, the conductivity between the power supply pin 24 and the cylindrical power supply portion 23a is not impaired, and good electrical conductivity is maintained.
[0014]
【The invention's effect】
As described above, according to the present invention, a pair of internal lead rods extending into the sealed body from the sealed portions at both ends of the sealed body are electrically connected to both ends of the rod-shaped heating element arranged along the tube axis of the tubular sealed body. In an electrically connected lamp, a conductive power supply pin is connected to the end of the heating element, and a cylindrical power supply is formed at the tip of the internal lead rod, and the cylindrical power supply is slidable on the power supply pin. Therefore, the lamp can reliably absorb the thermal expansion of the rod-shaped heating element.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing another embodiment.
FIG. 3 is an explanatory diagram of a conventional example.
[Explanation of symbols]
Reference Signs List 10 Sealing body 11 Sealing part 21 Molybdenum foil 22 External lead rod 23 Internal lead rod 23a Internal lead rod cylindrical power supply part 23b Internal lead rod coil fixing part 23c Internal lead rod spring part 24 Power supply pin 25 Fixed coil 30 Heat generation Body 31 Base 32 Carbon

Claims (1)

In a lamp in which a pair of internal lead rods extending from the sealing portions at both ends of the envelope into the envelope are electrically connected to both ends of a rod-shaped heating element arranged along the tube axis of the tubular envelope,
A conductive power supply pin is connected to the end of the heating element, and a cylindrical power supply is formed at the tip of the internal lead rod,
The lamp, wherein the cylindrical power supply portion is slidably fitted to the power supply pin.

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