JPH0430767Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a tube-type incandescent light bulb for illuminating manuscripts, which has a structure in which the non-light emitting part of the filament is held by a reduced diameter part formed in a glass envelope. It is something.

[Background of the idea]

For example, in an example of a tube-type incandescent light bulb for document illumination that is sealed at both ends and used as an exposure light source in a copying machine, light-emitting parts and non-light-emitting parts are arranged alternately in order to obtain a good light distribution. A so-called partially emissive type filament made of a glass material is disposed within a glass enclosure.

Therefore, in order to obtain an appropriate light distribution, it is necessary that the filament be arranged with high accuracy along the tube axis of the glass enclosure. Therefore, in the past, a ring-shaped supporter was provided in the non-light emitting part of the filament, and this supporter was brought into contact with the inner wall of the glass enclosure to hold the filament.

However, with this method, it is necessary to attach a ring-shaped supporter to the filament, which makes the structure of the filament complicated, and there is a problem in that it takes time and effort to place the filament with the ring-shaped supporter attached inside the enclosure. There is.

[Problem that the invention attempts to solve]

In response to this, the present inventor has conducted intensive research on a means for forming a reduced diameter part in a portion of the glass enclosure facing the non-light emitting part and holding the non-light emitting part by the reduced diameter part. Such a holding structure is advantageous in that the structure of the filament is simple.

However, a new problem was discovered here. In other words, in a heat-generating light bulb that has a structure in which the non-light emitting part of the filament is held by a reduced diameter part formed in a glass envelope, the emitted light from the light emitting part is diffusely reflected by the glass in the reduced diameter part, or the light emitted from the reduced diameter part is reflected. Glass causes complicated refraction of light, resulting in large ripples in the light distribution.

[Purpose of invention]

The present invention was developed based on the above-mentioned circumstances, and its purpose is to provide an incandescent lamp with a structure in which the non-light-emitting part of the filament is held by a reduced diameter part formed in a glass envelope, and to provide a good quality product without ripples. An object of the present invention is to provide an incandescent light bulb that can obtain a light distribution.

[Means for solving problems]

In the present invention, a filament in which a light-emitting part and a non-light-emitting part are arranged alternately is arranged along the tube axis of a glass enclosure, and the non-light-emitting part is attached to the glass enclosure at one end and the other end. In a tube-type incandescent light bulb for document illumination, the light-emitting portion of the filament is The end portion is located on the opposite side of the reduced diameter portion in the tube axis direction from the bending start position of the reduced diameter portion that holds the adjacent non-light emitting portion.

[Function and effect of the idea]

According to the present invention, the non-light emitting part of the filament is held at one end and the other end by the reduced diameter part of the seal, and the reduced diameter part extends over the entire circumference of the tube wall. The light-emitting part is held sufficiently to prevent the filament from wobbling, and the end of the light-emitting part of the filament is held in place in the tube axis direction from the bending start position of the reduced diameter part that holds the adjacent non-light-emitting part. Since the structure is located on the opposite side of the reduced diameter part, the end of the light emitting part is slightly separated from the reduced diameter part, so that the part of the light emitted from the light emitting part that is adversely affected by the reduced diameter part is reduced. Since the ratio is considerably reduced, the light distribution becomes ripple-free, and the reduced diameter part is a narrow constriction formed by deforming the tube wall of the envelope so as to bend inward over its entire circumference. Therefore, the distribution of light transmitted through the reduced diameter portion becomes uniform over the entire circumference of the tube wall, and from this point as well, an appropriate light distribution without ripples can be obtained.

[Specific structure of the idea]

Hereinafter, the configuration of the present invention will be specifically explained with reference to the drawings.

FIG. 1 is an explanatory diagram showing an example of an incandescent light bulb according to the present invention, in which 10 is a glass envelope formed of a glass tube, 20 is a filament, and 30 is a lead rod.

In this incandescent light bulb, a filament 20 in which a light-emitting part 21 and a non-light-emitting part 22 are arranged alternately is arranged along the tube axis P of a glass envelope 10, and the non-light-emitting part 22 is arranged inside the glass envelope 10. The end portion 21A of the light emitting portion 21 of the filament 20 is held by a reduced diameter portion 12 formed in The reduced diameter part 1 in the P direction
2 is located on the opposite side. Here, the "reduced diameter section" refers to a part where the tube wall of the glass envelope 10 is narrowed over its entire circumference so as to approach the tube axis when the glass envelope 10 is viewed from the tube axis direction. refers to the part of the shape that has been

The filament 20 has a light emitting part 21 and a non-light emitting part 2.
2 are arranged alternately, the light emitting part 21 is formed by a tightly wound coil, and the non-light emitting part 22 is formed by inserting a shorting rod 23 into a loosely wound coil. The coil portion is made of tungsten, for example.

As shown in FIG. 2, the glass tube for forming the glass envelope 10 is a glass tube in which a reduced diameter portion 12 is formed in advance at a predetermined position, that is, at a portion that faces the non-light emitting portion 22. tube 15
can be used. The reduced diameter portion 12 can be formed by locally heating the outer circumferential surface of a straight glass tube using an appropriate heating means to narrow the tube. Reference numeral 16 denotes a reduced diameter portion on the end side for forming the sealing portion 11.

One non-light emitting part 22 is held at both ends by two reduced diameter parts 12 formed in the glass enclosure 10. That is, the non-light-emitting portion 22 is connected to the reduced diameter portion 1 at two points, one end and the other end.
2 is maintained. Therefore filament 2
0 wobble is sufficiently prevented, and no disturbance of the light distribution occurs.

Here, the "bending start position 12A of the reduced diameter portion 12" refers to the position at which the bending starts inward so that the reduced diameter portion 12 is formed on the inner circumferential surface of the glass enclosure 10, as shown in FIG. The starting position. And "the end 21A of the light emitting part 21 of the filament 20" means:
This refers to the end of the tightly wound coil that constitutes the light emitting section 21.

According to the incandescent lamp with the above configuration, the non-light-emitting portion 22 of the filament 20 is held at one end and the other end by the reduced diameter portion 12 of the envelope, and the reduced diameter portion is formed around the entire circumference of the tube wall. Therefore, the non-light-emitting portion 22 is sufficiently held and the wobbling of the filament 20 is sufficiently prevented.
The end portion 21A of the light emitting portion 21 of the filament 20 is
Since the structure is such that the bending start position 12A of the reduced diameter part 12 holding the adjacent non-light emitting part 2 is located on the opposite side of the reduced diameter part 12 in the direction of the tube axis P,
In other words, the end part 21A of the light emitting part 21 is slightly separated from the adjacent diameter reducing part 12, and the proportion of light that is adversely affected by the diameter reducing part 12 out of the light emitted from the light emitting part 21 is considerably reduced, so that the light distribution is improved. The distribution is ripple-free, and since the reduced diameter part is formed by deforming the tube wall of the enclosure so as to bend inward over its entire circumference, the reduced diameter part has no ripples. The distribution of light transmitted through the tube wall becomes uniform over the entire circumference of the tube wall, and from this point as well, an appropriate light distribution without ripples can be obtained.

Incidentally, when the amount of light emitted by one light emitting part was measured for each of the incandescent light bulb according to the present invention employing the above configuration and an incandescent light bulb manufactured for comparison, the results shown in FIG. 4 were obtained. The incandescent light bulb for comparison has the same configuration as the incandescent light bulb according to the present invention, except that the end of the light emitting part is placed at a position that extends into the reduced diameter part from the bending start position of the adjacent reduced diameter part. . In the figure, curve A shows the results using the incandescent light bulb according to the present invention, and curve a shows the results using the comparative incandescent light bulb. As can be understood from this result, in contrast to the comparative incandescent bulb, where the light intensity attenuates significantly on the end side of the light emitting part, the incandescent bulb according to the present invention shows such attenuation in the light intensity. can be considerably suppressed.

Furthermore, JP-A No. 48-36278 discloses a configuration in which a convex portion that protrudes inward is formed on a part of the glass envelope and the non-light-emitting portion of the filament is held by this convex portion. However, since this protrusion does not cover the entire circumference of the tube wall of the envelope, it is uncertain whether the non-light-emitting part can be held securely, and the tube wall where the protrusion exists may have a problem with light transmission in the circumferential direction. The non-uniformity of the condition is large, which causes disturbances in the light distribution. However, in the present invention, since the reduced diameter part extends over the entire circumference of the pipe wall, the transmission in the circumferential direction of the reduced diameter part is reduced. The distribution of light becomes uniform, and from this point as well, there is no disturbance in the light distribution.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view showing an example of an incandescent light bulb according to the present invention, FIG. 2 is an explanatory cross-sectional view showing an example of a glass tube for forming an enclosure, and FIG. FIG. 4 is an explanatory sectional view showing the main parts, and FIG. 4 is an explanatory view showing the measurement results of the amount of light. 10... Glass sealing body, 11... Sealing part, 12
...Reduced diameter part, 12A...Bending start position of reduced diameter part,
15... Glass tube, 16... End side reduced diameter part, 20
...Filament, 21...Light emitting part, 21A...
End of light-emitting part, 22... Non-light-emitting part, 30... Lead rod, P... Tube shaft.

Claims (1)

[Claims for Utility Model Registration] A filament in which light-emitting parts and non-light-emitting parts are arranged alternately is arranged along the tube axis of a glass enclosure, and the non-light-emitting parts have, at one end and the other end, In a tube-type incandescent light bulb for document illumination, the filament is held by a narrow diameter part formed by deforming the tube wall of a glass envelope so as to bend inward over its entire circumference. A tube type for document illumination, characterized in that the end of the light emitting part is located on the opposite side of the reduced diameter part in the tube axis direction from the bending start position of the reduced diameter part that holds the adjacent non-light emitting part. Incandescent light bulb.