JPH076617Y2 - Tube incandescent light bulb - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a tubular incandescent light bulb that is preferably used as, for example, an exposure light source of a copying machine.

[Conventional technology]

For example, as a light source for exposure of a copying machine, a non-light-emitting portion formed by inserting and fixing a short-circuit core wire in a coil, a light-emitting portion formed of a close-wound coil, and a position between the non-light-emitting portion and the light-emitting portion are provided. A tube-type incandescent light bulb having a filament coil having a connection portion composed of an open coil is used.

Then, this type of incandescent light bulb is used in a blinking lighting mode in which it is lit when exposing a document and is otherwise lit.

[Problems to be solved by the device]

However, when the conventional tubular incandescent light bulb is used in the flashing lighting mode, there is a problem that the service life is considerably shortened as compared with the case where it is used in the continuous lighting mode.

Therefore, as a result of earnest studies, the inventor of the present invention repeatedly generates heat and cools the light emitting part by blinking and lighting, and as a result, thermal stress is generated in the filament coil, which shortens the service life. Found.

That is, when a lighting current is supplied to the tube-shaped incandescent light bulb for lighting, the light emitting portion of the filament coil heats up due to resistance heat and emits light, but the heat at this time causes the coil wire to expand. Therefore, the entire light-emitting portion including the close-wound coil extends considerably in the axial direction. Also, when the supply of the lighting current to the tubular incandescent light bulb is stopped for turning off the light, by cooling the light emitting unit,
Due to thermal expansion, it contracts from the stretched state to the whole. Then, in use in the blinking lighting mode, such expansion and contraction of the light emitting portion of the filament coil is repeated at relatively short time intervals.

However, in the non-light emitting portion of the filament coil, since the short-circuit core wire is inserted and fixed in the coil continuous to the light emitting portion, the free extension or contraction of the coil of the non-light emitting portion is almost limited. In such a situation, the expansion and contraction of the light emitting portion are repeated at relatively short time intervals, so that strain is repeatedly generated particularly in the coil wire at the boundary between the light emitting portion and the non-light emitting portion of the filament coil. As a result, the coil wire is broken due to metal fatigue. A phenomenon that occurs in the filament coil due to heat generation and cooling of the light emitting portion and causes destruction of the coil wire is called "thermal stress".

As a result of further intensive research based on such knowledge, it was found that the value of the product of the coil pitch and the number of turns was within a certain range and the coil pitch was within a certain range in the loosely wound coil at the connecting portion. For example, when the flashing lighting mode is used, the thermal stress in the filament coil is efficiently absorbed by the loosely wound coil of this connection part, and a sufficient service life is obtained, and the present invention has been completed. Is.

That is, it is an object of the present invention to provide a tubular incandescent light bulb that can obtain a sufficiently long service life when used in a blinking lighting mode.

[Means for Solving the Problems]

In order to achieve the above object, in the present invention, a non-light emitting part formed by inserting and fixing a short-circuit core wire in a coil made of tungsten, a light emitting part made of a close-wound coil, the non-light emitting part and the light emitting part. A tubular incandescent light bulb used in a flashing lighting mode, comprising a filament coil having a connection part made of a loosely coiled coil located between and, wherein the loosely coiled coil of the connecting part is a coil. Pitch is P (%),
When the number of turns is T, a configuration that satisfies the following conditions and is adopted.

Condition: 700 ≦ P × T ≦ 1300 Condition: 150 ≦ P ≦ 500 (where, the coil pitch P is the diameter of the coil wire a,
When the width of the coil gap between the coil wires is b, It means the ratio represented by. ) [Operation] Since the loose coil of the connection portion satisfies the conditions and, as will be understood from the description of the experimental example described later, when used in the blinking lighting mode, the filament is generated by heat generation and cooling of the light emitting portion. The thermal stress generated in the coil is efficiently absorbed in the loosely coiled coil of the connecting portion due to displacement or the like in the loosely coiled coil.

〔Example〕

In the embodiment shown in FIG. 1, a non-light emitting portion 20 formed by inserting and fixing a short-circuit core wire 21 made of molybdenum in a coil made of tungsten, and a coil pitch of 150% (this coil pitch is the sparsely wound coil). Is defined in the same manner as the coil pitch of the above).
A tubular incandescent light bulb used in a blinking lighting mode, which includes a filament coil 40 having a connection portion 30 formed of a loose coil located between the non-light emitting portion 20 and the light emitting portion 10. Therefore, the loosely wound coil of the connection part 30 is configured as follows.

That is, as shown in an enlarged manner in FIG. 2, when the coil pitch of the loosely wound coil of the connection portion 30 is P (%) and the number of turns is T, the loosely wound coil is configured to satisfy the following conditions and To do.

Condition: 700 ≦ P × T ≦ 1300 Condition: 150 ≦ P ≦ 500 The length of the connecting portion 30 is the same as the conventional one and is about 1 to 2 mm.

[Experimental example]

Next, an example of an experiment conducted to confirm the effect of the present invention will be described.

In each of the experimental examples, a tube-type incandescent light bulb having a connection part 30 composed of a loosely coiled coil under the conditions shown in Table 1 below and having the same configuration as in FIG. After repeating the on time of 2.3 seconds and the off time of 0.7 seconds 100 times, the service life was examined when used in the blinking lighting mode in which the light was turned off for 5 minutes. Also, the service life when used in the continuous lighting mode was examined.

In the above tubular incandescent light bulb, the filament coil has a wire diameter of 0.14 mm, the total length of the connecting portion 30 is 1.5 mm, and the rated power is 250 W (voltage = 85 V, current = 2.9 A).

As can be seen from the results in Table 1, in Experimental Example 1, the loosely wound coil at the connection portion does not satisfy the conditions, and therefore the service life is short in use in the blinking lighting mode. Also,
In Experimental Example 5, since the loosely wound coil at the connection portion did not satisfy the conditions, the filament drooped early and could not be used.

On the other hand, in Experimental Examples 2, 3, and 4, since the loosely coiled coil of the connection portion satisfies the conditions and, and adopts the configuration of the present application, the service life in the use in the blinking lighting mode is experimental. It was 1.9 times more than that of Example 1, which was significantly longer.

In addition, in the use in the continuous lighting mode, Experimental Example 1
No. 4 to No. 4 had the same service life, and no significant difference was observed. It is considered that this is because the thermal stress as in the case of using the flashing lighting mode does not pose a problem.

[Effect of device]

As described above, according to the tubular incandescent light bulb of the present invention,
Since the loosely coiled coil of the connection portion satisfies the conditions and, the thermal stress generated in the filament coil due to heat generation and cooling of the light emitting portion is efficiently applied to the loosely coiled coil of the connection portion when used in the blinking lighting mode. It will be absorbed, and as a result, the service life will be significantly extended.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a tubular incandescent lamp according to the present invention, and FIG. 2 is an explanatory view showing an enlarged connecting portion. 10 …… Light emitting part, 20 …… Non-light emitting part 21 …… Short-circuit core wire, 30 …… Connecting part

Claims (1)

[Scope of utility model registration request] 1. A non-light emitting portion formed by inserting and fixing a short-circuit core wire in a coil made of tungsten, a light emitting portion made of a close-wound coil, and a light emitting portion positioned between the non light emitting portion and the light emitting portion. What is claimed is: 1. A tube-type incandescent lamp used in a flashing lighting mode, comprising: a filament coil having a connection part composed of a loose coil, wherein the loose coil of the connection part has a coil pitch of P (%). ,
A tube-type incandescent light bulb which satisfies the following conditions when the number of turns is T. Condition: 700 ≦ P × T ≦ 1300 Condition: 150 ≦ P ≦ 500 (where, the coil pitch P is the diameter of the coil wire a,
When the width of the coil gap between the coil wires is b, It means the ratio represented by. )