JPH0433641Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a tube-type light bulb that is incorporated into, for example, a document illumination device of a copying machine. For example, in the document illumination device of a copying machine, a tube-type light bulb called a partial emission type is used, in which a plurality of filament coils are arranged at intervals corresponding to the light distribution pattern to be formed on the document table. . In this type of tube-type light bulb, it is necessary that the position of each filament coil not be displaced from the tube axis of the envelope so that a predetermined light distribution pattern is always formed on the document table. For example, as shown in FIGS. 1 and 2, such a tube-type light bulb includes a light-emitting coil portion 21 and a continuous light-emitting coil portion 21 at both ends of the light-emitting coil portion 21 in the tube-type enclosure 1 along the tube axis. A plurality of filament coils 2 consisting of connection coil portions 22 are arranged spaced apart, and two filament coils 2 adjacent to each other,
A shorting wire 5 is disposed between each of the filament coils 2, and the connecting coil portion 22 of the filament coil 2 is wound around each end of the shorting wire 5, and the two are electrically connected by spot welding. In the figure, 4 is a ring-shaped supporter formed on the shorting wire 5, and 6 is a metal foil 6.
1 and an external lead electrically connected to the outermost filament coil 2 via an internal lead 62. However, conventional tube-type light bulbs, especially tube-type light bulbs in which the diameter of the wire constituting the filament coil 2 is 0.08 to 0.3 mm and the diameter of the wire constituting the shorting wire 5 are 0.3 to 1.0 mm, cannot be lit. Due to thermal deformation caused by heat generated during the operation, the coil of the connection coil section 22 wound around the tip of the shorting wire 5 may separate from the shorting wire 5 as shown by the chain line in FIG. Therefore, the filament coil 2 was often displaced downward from the tube axis of the envelope 1 due to its own weight, resulting in a significant decrease in light distribution accuracy. The present invention was developed against the above background, and the purpose is to provide a tube-type light bulb in which the connecting coil portion of the filament coil is less likely to separate from the short-circuit wire and maintains excellent light distribution accuracy. Its characteristics are that filament coils and short-circuit wires are arranged alternately along the tube axis inside the tube-shaped enclosure, and the connecting coil part at the end of the filament coil is wrapped around the end of the short-circuit wire. It is a tube type light bulb which is connected by turning the two, and the diameter of the wire constituting the filament coil is
0.08~0.3mm, the diameter of the strands constituting the shorting wire is
In the case where the pitch is 0.3 to 1.0 mm, the coil pitch in the connecting coil portion of the filament coil is 4 mm or less. An embodiment of the present invention will be described below with reference to FIG. In this embodiment, filament coil 2
The diameter of the wire constituting the short-circuit wire 5 is 0.3 to 1.0 mm, and the coil pitch p of the connecting coil portion 22 of the filament coil 2 is preferably 4.0 mm or less, preferably It is configured to be 3.0mm or less. As described above, in the present invention, in a tube type light bulb in which the diameter of the wire of the filament coil 2 and the diameter of the wire of the shorting wire 5 are within a specific range, the coil pitch of the connecting coil portion 22 of the filament coil 2 is By reducing p to a certain value or less, as is clear from the experimental examples described later, detachment of the coil of the connecting coil portion 22 at the tip of the shorting wire 5 is significantly suppressed, and therefore the intended arrangement is achieved. Optical precision can be stably maintained over a long period of time. Next, an example of an experiment conducted to confirm the effects of the present invention will be described. The diameter of the wire of the filament coil 2 (hereinafter referred to as "d"
It is expressed as ), the diameter of the strand of the shorting wire 5 (hereinafter referred to as "D")
It is expressed as ) and the coil pitch p of the connecting coil section 22 was conducted for 5 minutes on five types of tube-shaped light bulbs A to E, each having the values shown in Table 1. During this experiment, an accident occurred in which the connecting coil section 22 separated from the shorting wire 5. The incidence rate of % was investigated. The tube-shaped light bulbs used in the experiment had a rated voltage of 80V and a rated power of 350W.
The results of the experiment are also shown in Table 1.

[Table] From the above results, the three types of tube-type light bulbs A, B, and C that fall within the scope of the present invention have a higher connection coil than the two types of tube-type light bulbs D and E that do not fall within the scope of the present invention. It has been confirmed that the incidence of breakaway accidents in section 22 is significantly lower, and that it is extremely useful in practice.

[Brief explanation of the drawing]

FIG. 1 is a sectional view schematically showing a tube-type light bulb, and FIG. 2 is a partially enlarged view showing a connection state between a filament coil and a shorting wire of the tube-type light bulb. 1... Envelope, 2... Filament coil, 21
...Light emitting coil section, 22... Connection coil section, 4...
...Supporter, 5...Short wire, 6...External lead.

Claims (1)

[Claim for Utility Model Registration] Filament coils and short-circuit wires are arranged alternately along the tube axis in a tubular enclosure, and the connecting coil portion at the end of the filament coil is wound around the end of the short-circuit wire. It is a tube type light bulb formed by connecting both the filament coil and the filament coil, and the diameter of the wire constituting the filament coil is
0.08~0.3mm, the diameter of the strands constituting the shorting wire is
A tube-type light bulb having a coil pitch of 0.3 to 1.0 mm, characterized in that the coil pitch in the connecting coil portion of the filament coil is 4 mm or less.