JP2001202926A - Incandescent lamp for heat source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an incandescent lamp for a heat source for enabling generation of sufficiently more heat at both ends than in the central area, when the lamp continues to be 'ON', and control the amount of heat generated so that the heat generated does not become relatively excessive at the both ends thereof, when the lamp is turned 'ON' and 'OFF'. SOLUTION: An incandescent lamp for a heat source has a plurality of light- emitting portions 26, 27 and a non light-emitting portion 28, arranged alternately in a tube type bulb 21 along tube axis direction thereof. The light-emitting portions 27, 27 positioned at both ends of the tube type bulb comprise a filament for generating more heat than light-emitting portions 26, except such portion on the both ends. On both ends of the tube type bulb, there is provided a means 29 having a prescribed heat capacity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an incandescent lamp for a heat source, and more particularly to an incandescent lamp for a heat source used for a heating roller of an electrophotographic copying machine or a printer.

[0002]

2. Description of the Related Art Conventionally, a heating roller for an electrophotographic copying machine or a printer has a heat source incandescent lamp incorporated therein as a heat source. JP-A-10-106510
Japanese Patent Application Laid-Open Publication No. H11-15764 discloses an example of such an incandescent lamp for a heat source.

FIG. 5 is a front view showing an example of a heating roller used in a fixing device such as an electrophotographic copying machine or a printer according to the prior art.

As shown in FIG. 1, a heating roller 10 includes a heat source incandescent lamp 20 inside a sleeve-shaped roller body 11.
The rotation driving gear 12 is fixed to one end of the roller body 11 and the other end is supported by a rotation support member 13 so as to be rotatable.

Normally, the heating roller 10 is required to have a uniform surface temperature in its length direction. However, heat is taken from both ends of the roller body 11 by a rotation driving gear 12 and a rotation supporting member 13. In addition, since the heat dissipating effect is greater than that of the central region, simply heating the roller body 11 uniformly in the longitudinal direction would significantly lower the surface temperature of the heating roller 10 at both ends. In order to avoid such a situation, in order to make the surface temperature of the heating roller 10 uniform over the entire length, the degree of heating at both ends of the heating roller 10 is set to be higher than that in the other central region. ing.

FIG. 6 is a front view showing a configuration of a heat source incandescent lamp for increasing the amount of heat generated at both ends of the heating roller 10 from the central region.

As shown in FIG. 1, an incandescent lamp 20 for a heat source is used.
The filament support 24 is provided with a filament 24 in which a plurality of light-emitting portions 26 and 27 and a non-light-emitting portion 28 are alternately arranged along a tube axis direction in a glass tubular valve 21. Is installed and the filament 24
Are connected to a metal foil 22 made of molybdenum foil or the like embedded in pinch seal portions at both ends of the bulb 21 and external lead rods 23 extending from the metal foil 22. Further, as shown in FIG.
And two central region light emitting portions 26 corresponding to the central region, and a larger amount of heat is obtained in the end light emitting portions 27, 27. For this reason, the length of the heating coil is set to be longer than that of each central area light emitting unit 26.

By using such an incandescent lamp 20 for the heat source as a heat source of the heating roller 10, the amount of heat generated by the end light emitting portions 27 at both ends of the filament 24 becomes larger than that of the central region light emitting portion 26. Both ends of the roller 10 are heated more strongly than the central region, so that the surface temperature of the heating roller 10 is made uniform in the length direction.

On the other hand, a heating roller used in an electrophotographic copying machine or a printer has a so-called warming-up time in which the surface temperature of the heating roller rises to a usable temperature range within a short time immediately after the main switch of the apparatus is turned on. The roller surface temperature is stable in the usable temperature range so that the intended heat treatment can be performed at any time during the processable period (standby period) after the temperature has risen to the usable temperature range. Needs to be maintained. For this reason, as a lighting circuit for lighting the incandescent lamp for heat source used for such a heating roller, a continuous lighting function for continuously energizing and lighting the incandescent lamp for heat source during the warm-up period, and a lighting circuit after the warm-up is completed. A device having an on / off lighting function of intermittently supplying power for a relatively short time during a standby period is used.

[0010]

However, in the conventional incandescent lamp for a heat source, in the continuous lighting during the warm-up period of the heating roller, the degree of heating at both ends is larger than that in the central region, so that the temperature at both ends is increased. Although it is possible to prevent the drop, the on / off lighting during the standby period is less than the continuous lighting during the warm-up period.
It is known that the surface temperature at both ends of the heating roller becomes relatively higher than the surface temperature in the central region, and the temperature distribution in the length direction becomes non-uniform.

FIG. 7 is a diagram showing the heat distribution characteristics of the incandescent lamp 20 for a heat source having the above-mentioned filament configuration.

In FIG. 1, the horizontal axis is the incandescent lamp 2 for a heat source.
0 indicates the heat distribution width in both the left and right directions with the center as the base point, and the vertical axis indicates the relative heat output of each part with respect to the average heat output in the central region of the incandescent lamp 20 for heat source. In the case of lighting and intermittent lighting by ON / OFF energization, when the ON time is 0.5 seconds and the OFF time is 1.5 seconds, the ON time is 0.3 seconds and the OFF time is 1.7. 2 seconds, and a case where the ON time is 0.2 seconds and the OFF time is 1.8 seconds.

As is apparent from FIG. 1, the amount of heat generated at both ends of the incandescent lamp 20 for the heat source is higher in the case of the conventional on / off lighting than in the case of the continuous lighting. Show a tendency to become For this reason, the surface temperature at both ends of the heating roller 10 becomes excessively high.

In this characteristic diagram, the reason why the heat generation amount at both ends becomes higher as the ON time becomes shorter is that the ratio of the heat generation amount at both ends to the heat generation amount in the central region becomes larger as the ON time becomes shorter. Because.

In recent years, the thickness of the metal sleeve constituting the roller body of the heating roller has tended to be thin, and when such a heating roller is used, the above-mentioned uneven temperature distribution is not uniform. The problem becomes more pronounced. Further, the phenomenon that the surface temperature of the heating roller becomes excessive at both ends is promoted by consuming heat only in the central portion of the heating roller when fixing an image forming sheet such as paper having a small width. You.

In view of the above problems, it is an object of the present invention that the amount of heat generated at both ends during continuous lighting is sufficiently larger than that at the center region, and the amount of heat generated at both ends is relatively large during on / off lighting. An object of the present invention is to provide an incandescent lamp for a heat source, which is capable of suppressing an excessive increase.

[0017]

The present invention employs the following means in order to solve the above-mentioned problems.

The first means is that a plurality of light-emitting portions and non-light-emitting portions are alternately arranged in the tube-shaped bulb along the tube axis direction, and the light-emitting portions located at both ends of the tube-shaped bulb are arranged. In the incandescent lamp for a heat source, comprising a filament having a larger calorific value than a light emitting portion located at other than the both ends, a means having both ends of the tubular bulb having a predetermined heat capacity larger than a central region other than the both ends. It is characterized by having given.

The second means is that, in the first means, the means having a predetermined heat capacity larger than the central region other than the both ends is a coil wound around the outer periphery of both ends of the tubular valve. Features.

A third means is the first means, wherein the means having a predetermined heat capacity larger than the central region other than the both ends is a ceramic or carbon film coated on both ends of the tubular valve. It is characterized by.

The fourth means is the first means, wherein the means having a predetermined heat capacity larger than the central region other than the both ends is the tubular glass or the tubular mold attached to both ends of the tubular valve. It is characterized in that the thickness of both ends of the valve is increased.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a front view showing the configuration of the incandescent lamp for a heat source according to the present invention, and FIG. 2 is an enlarged sectional view of the end of the incandescent lamp for a heat source shown in FIG.

In these figures, reference numeral 1 denotes an incandescent lamp for a heat source according to the present invention, and 29 denotes a predetermined area larger than a central area other than the both ends at both ends of the incandescent lamp for heat source 1 located at the end light emitting portion 27. An external coil wound around the outer periphery of the valve 21, a coil fixing portion 30 of the external coil 29 fixed to the pinch seal portion 31, and a pinch seal portion 31 are members for providing a heat capacity of. Note that the other configuration corresponds to the configuration of the same reference numeral shown in FIG.

It should be noted that the filament 24 has light emitting portions 26 and 2
7 and the non-light-emitting portions 28 are alternately arranged. The non-light-emitting portions 28 may be short-circuited core wires, or a filament coil constituting the filament 24 may be wound more coarsely than the light-emitting portions 26 and 27. May be done.

The specification of the external coil 29 uses a Kanthal wire having an effective number of turns of 25 turns, a coil pitch of 350%, and a coil wire diameter of φ0.8. An alloy having a melting point was used.

Here, the coil pitch is defined as a wire diameter a
Is the factor expressed as b / a, where b is the distance traveled by one turn in the coil.

FIG. 3 shows an incandescent lamp 1 for a heat source according to the present invention.
FIG. 3 is a heat output characteristic diagram showing a temporal change of each heat output in a central region and both end portions of the incandescent lamp 1 for a heat source.

As shown in the characteristic diagram, the heat output in the central region is higher than the heat output at both ends until approximately 200 seconds elapse, but the heat output at both ends increases after approximately 200 seconds elapse. Greater than the heat output in the central area.

As described above, according to the invention of this embodiment,
Since the external coil 29 is wound around both ends of the incandescent lamp for heat source 1 as members having a predetermined heat capacity larger than the central region, the generation of heat from both ends of the incandescent lamp for heat source 1 reduces the heat from the central region. In the case of ON / OFF lighting, as shown in FIG. 3, ON / OFF lighting is repeated during a time period in which the heat output at both ends is smaller than the heat output in the central region. The amount of heat generated from both ends of the heat source incandescent lamp 1 can be made smaller than the amount of heat in the central region. As a result, the surface temperature of the heating roller during the standby period can be made uniform.

FIG. 4 shows an incandescent lamp 1 for a heat source according to the present invention.
FIG. 4 is a characteristic diagram showing heat distribution characteristics of the present invention.

In the figure, the horizontal axis is the incandescent lamp 1 for a heat source.
Represents the heat distribution width in both the left and right directions with respect to the center of the incandescent lamp, and the vertical axis represents the relative heat output of each part with respect to the average heat output in the central region of the incandescent lamp 1 for heat source. In the case of and the intermittent lighting by ON / OFF energization, the ON time is 0.5 seconds and the OFF time is 1.5 seconds.
In the case of seconds, the on time is 0.3 seconds and the off time is 1.7
2 seconds, and a case where the ON time is 0.2 seconds and the OFF time is 1.8 seconds.

As is apparent from FIG. 3, in the present invention, the amount of heat generated at both ends of the incandescent lamp 1 for the heat source is larger in both cases of on / off lighting than in the case of continuous lighting. Can also be lower. That is, when the incandescent lamp 1 for a heat source according to the present invention is used as a heat source for a heating roller of an electrophotographic copying machine or a printer, the surface temperature of both ends of the heating roller at the time of ON / OFF lighting during a standby period is reduced. Excessive rise can be suppressed.

The external coil 29 used in this embodiment is
When the pitch width is widened, the peak value at both ends of the incandescent lamp for heat source 10 at the time of on / off lighting tends to be high because the pitch width is wide and the heat capacity cannot be increased. Also, if the wire diameter of the external coil 29 is reduced, the peak value at both ends of the incandescent lamp for heat source 10 at the time of on / off lighting cannot take up the entire volume of the external coil 29, so that the heat capacity cannot be gained. It tends to be higher. Thus, by setting the coil pitch and the wire diameter of the external coil 29 to appropriate values, any heat distribution characteristics of the incandescent lamp for a heat source at the time of ON / OFF lighting can be obtained.

In the present embodiment, the external coil 29 is used as a member for providing a predetermined heat capacity at both ends located at the end light emitting portions 27 of the incandescent lamp 1 for a heat source. The member is not limited to the external coil, and other members may be used as long as they have a predetermined heat capacity larger than the central region other than the both ends.

For example, as a member for increasing the heat capacity, the surface of the bulb at both ends of the incandescent lamp for a heat source may be coated with a ceramic or carbon film, or infrared converting means in which the bulb is doped with copper or the like may be used. Moreover,
As means for increasing the heat capacity, glass tubes may be placed on both ends of the incandescent lamp for a heat source, or the thickness of the bulb at both ends of the incandescent lamp for a heat source may be increased from the time of molding the bulb. In either case, the heat generation from both ends of the heat source incandescent lamp can be delayed in time compared to the heat generation from the central region, and the surface temperature of the heating roller during the standby period during on / off lighting can be reduced. It can be made uniform.

[0037]

According to the first to fourth aspects of the present invention, during continuous lighting, the amount of heat generated at both ends of the incandescent lamp for a heat source can be made sufficiently larger than that in the central region, and the amount of heat generated can be increased. At the time of off-lighting, desired heat distribution characteristics are obtained such that the amount of heat generated at both ends does not become relatively large.

According to the second aspect of the present invention, by adjusting the coil pitch width or setting the coil wire diameter to an appropriate value, the incandescent lamp for a heat source at the time of on / off lighting is provided. Arbitrary heat distribution characteristics can be obtained.

According to the third and fourth aspects of the present invention, it is possible to improve the heat distribution characteristics of the incandescent lamp for a heat source during on / off lighting by simple means.

[Brief description of the drawings]

FIG. 1 is a front view showing a configuration of an incandescent lamp for a heat source according to the present invention.

FIG. 2 is an enlarged sectional view of an end of the incandescent lamp for a heat source shown in FIG.

FIG. 3 is a heat output characteristic diagram of the incandescent lamp for a heat source according to the present invention.

FIG. 4 is a diagram showing heat distribution characteristics of the incandescent lamp for a heat source according to the present invention.

FIG. 5 is a front view of a heating roller used in a fixing device such as an electrophotographic copying machine or a printer according to the related art.

FIG. 6 is a front view showing a configuration of a conventional incandescent lamp for a heat source.

FIG. 7 is a diagram showing heat distribution characteristics of a conventional incandescent lamp for a heat source.

[Explanation of symbols]

 Reference Signs List 1 incandescent lamp for heat source 10 heating roller 11 roller body 12 rotation driving gear 13 rotation supporting member 21 tubular valve 22 metal foil (molybdenum foil) 23 external lead rod 24 filament 25 filament supporter 26 central area light emitting part 27 end light emitting part 28 Non-light emitting part 29 External coil 30 Coil fixing part 31 Pinch seal part

Claims (4)

[Claims] A plurality of light-emitting portions and non-light-emitting portions are alternately arranged along a tube axis direction in a tube-type bulb.
The light-emitting portions located at both ends of the tube-shaped bulb are incandescent lamps for a heat source provided with a filament having a larger calorific value than the light-emitting portions located at positions other than the both-ends. A means having a predetermined heat capacity larger than the central region of the incandescent lamp for a heat source. 2. The heat source for a heat source according to claim 1, wherein the means having a predetermined heat capacity larger than a central region other than the both ends is a coil wound around the outer periphery of both ends of the tubular valve. Incandescent lamp. 3. The heat source according to claim 1, wherein the means having a predetermined heat capacity larger than a central region other than both ends is a ceramic or carbon film coated on both ends of the tubular valve. For incandescent lamps. 4. The tubular glass according to claim 1, wherein the means having a predetermined heat capacity larger than a central region other than the both ends is a tubular glass attached to both ends of the tubular valve or a tubular glass attached to both ends of the tubular valve. An incandescent lamp for a heat source, characterized in that the wall thickness is increased.