JP5857620B2 - Tubular heater - Google Patents

Description

  Embodiments described herein relate generally to a tubular heater used for toner fixing of a copying machine or a printer.

  A tubular heater used for toner fixing of a copying machine or a printer has a structure in which a filament is arranged inside a glass tube. This lamp generally has a uniform light distribution characteristic in the tube axis direction. However, depending on the specifications of the apparatus to be mounted and the customer's request, there is a case where the light distribution is characterized in the tube axis direction. For example, in patent document 1, the light distribution design which makes a heat output higher than the center area | region of a tubular heater is higher than the center area | region. In such a light distribution design, as in Patent Document 2, a light emitting part and a non-light emitting part are provided, and the length in the tube axis direction of the light emitting part in the region where the heat output is desired to be increased is made longer than the other light emitting parts It was common to do.

  Recently, there is a need for a high-load and compact tubular heater. In such a tubular heater, the coil design is different from the conventional one. However, the design flexibility is narrowed, and it becomes difficult to give a special feature to the light distribution as in the conventional case.

JP 2001-202926 A JP 2007-286476 A

  The problem to be solved by the present invention is to provide a high-load and compact tubular heater capable of giving a characteristic to light distribution.

In order to achieve the above object, a tubular heater according to an embodiment includes a long glass tube having a space inside, a metal foil sealed at both ends of the glass tube, and a main part, and the main part Is a tubular heater comprising a filament connected to the metal foil so that the lamp power is P (W) and the main portion is disposed in the space. When the volume is V (mm ³ ), P / V ≧ 0.44 W / mm ³ is satisfied, and the main part includes a first coil part and a second coil part, and the first coil The portion is configured such that the coil pitch is 20% or more smaller than that of the second coil portion.

It is a figure for demonstrating the tubular heater of 1st Embodiment. It is a figure for demonstrating the edge part vicinity of the tubular heater of 1st Embodiment. It is a figure for demonstrating the light distribution in the tube-axis direction of a tubular heater when changing the coil pitch difference of a 1st coil part and a 2nd coil part. It is a figure for demonstrating the principal part of the filament of 1st Embodiment. It is a figure for demonstrating the fixing device of 2nd Embodiment. It is a figure for demonstrating the fixing roller of the fixing device of 2nd Embodiment.

  Hereinafter, embodiments for carrying out the invention will be described.

(First embodiment)
The tubular heater according to the first embodiment will be described with reference to the drawings. FIG. 1 is a diagram for explaining the tubular heater of the first embodiment, and FIG. 2 is a diagram for explaining the vicinity of the end of the tubular heater of the first embodiment.

  The tubular heater includes a glass tube 1 made of, for example, quartz glass as a main part. The glass tube 1 is an elongated tube, and is composed of a cylindrical portion 11 and a seal portion 12. The cylindrical portion 11 is a cylindrical portion that occupies most of the glass tube 1. In a part thereof, a chip 111 used for exhausting and introducing gas in the glass tube 1 is formed. The seal part 12 is a plate-like sealing part formed by pinch seals at both ends of the cylindrical part 11. Note that the seal portion 12 may have a cylindrical shape formed by a shrink seal.

  A space 13 is formed inside the glass tube 1. The space 13 is filled with, for example, a trace amount of a halogen substance such as nitrogen, bromine, or iodine, or a gas such as argon, neon, or nitrogen.

  The metal foil 2 is sealed inside the seal portion 12. The metal foil 2 is a thin plate made of molybdenum, for example, and is arranged along the plate-like surface of the seal portion 12.

  A filament 3 is provided inside the glass tube 1. The filament 3 is a metal wire made of tungsten, for example, and includes a main portion 31 and a leg portion 32. The main part 31 is a part arranged in the space 13. The leg portions 32 are portions that are located at both ends of the main portion 31 and are connected to the metal foil 2.

  A support member 4 is provided inside the glass tube 1. The support member 4 is a metal wire made of tungsten, for example, is fixed to the inner wall surface of the glass tube 1, and holds the main portion 31 so that the filament 3 is located at the center of the glass tube 1. A plurality of support members 4 are provided along the tube axis direction while maintaining a predetermined interval.

  A lead wire 5 is connected to the side of the metal foil 2 where the leg portion 32 is not connected. The lead wire 5 is a metal wire made of, for example, molybdenum or tungsten, and the other end is led out from the seal portion 12 so as to be along the tube axis.

  Here, in the present embodiment, as shown in FIG. 2, the main part 31 includes a first coil part 311 and a second coil part 312. The first coil portion 311 and the second coil portion 312 are coil portions formed in a spiral shape by winding a metal wire, and the first coil portion 311 has a coil pitch greater than that of the second coil portion 312. Is tightly wound so that is smaller than 20%. That is, the diameter of the metal wire in the first coil 311 is A1 (mm), the distance from the adjacent coil portion is B1 (mm), the diameter of the metal wire in the second coil 312 is A2 (mm), and the adjacent coil When the distance to the part is B2 (mm), the relationship | (B1 / A1) − (B2 / A2) | ≧ 0.2 is satisfied.

Hereinafter, an embodiment of the tubular heater will be described.
(Example)
Lamp length = 280mm,
The outer diameter R of the glass tube 1 is 5 mm, the inner diameter r is 3 mm,
The length of the space 13 in the tube axis direction = 230 mm,
Among them, the length L1 = 200 mm where the main part 31 is arranged,
The diameter A1 = 0.31 mm of the metal wire of the first coil portion 311, the distance B1 = 0.39 mm between adjacent coil portions, the coil pitch≈130%, the coil winding diameter C = 1.3 mm, the length in the tube axis direction L2 = 50 mm,
The diameter A2 of the metal wire of the second coil portion 312 = 0.31 mm, the distance B2 = 0.51 mm between adjacent coil portions, and the coil pitch≈170%.

  The tubular heater of this example was lit with a lamp power of 850 W. As a result, it was possible to obtain a characteristic light distribution in which both end regions emit light more strongly than the central region.

The tubular heater is required to be highly loaded and compact. High load and compact means that a large amount of electric power is supplied per unit volume. In the present invention, P / V (W / mm ³ ) is indicated from the lamp power P (W) and the volume V (mm ³ ) of the space 13 where the main portion 31 is disposed. V = L1 × π (r / 2) ² When P / V is increased, the load on the filament 3 is increased, so that a metal wire having a large diameter needs to be used. On the other hand, there are a number of turns necessary to obtain sufficient characteristics as a tubular heater. If the coil is to be wound with a necessary number of turns with a metal wire having a large diameter, the space 13 has less room than a metal wire with a small diameter. Therefore, it becomes difficult to provide a light emitting part and a non-light emitting part and to change the length of the light emitting part depending on the location in order to give the light distribution a special color as in the prior art. In particular, P / V is .44 / mm ³ or more, further comes to 0.50 W / mm ³ or more, the design flexibility is narrowed, it becomes difficult coil design to have a spot light distribution.

  Therefore, even in such a tubular heater with a narrow degree of design freedom, the first coil portion 311 is tightly wound so that the coil pitch is smaller than the second coil portion 312 by a predetermined amount so that the light distribution is characterized. The light distribution in the tube axis direction of the tubular heater was measured. The result is shown in FIG.

  From the results, it can be seen that when the first coil portion 311 is 120% and the second coil portion 312 is 140%, that is, when the coil pitch difference is 20%, the strength difference is 10% or more. It can be seen that when the coil pitch difference is 40%, the strength is slightly less than 20%, and when the coil pitch difference is 40%, the difference is approximately 25%. Although not shown, when the first coil portion 311 is 120% and the second coil portion 312 is 130%, the difference in strength is about 5%. If there is a difference of about 10%, preferably about 20% in strength between the first coil portion 311 and the second coil portion 312, the light distribution is characterized. A state. Therefore, in order to obtain a characteristic light distribution, the first coil portion 311 may be configured to have a coil pitch smaller than the second coil portion by 20% or more, desirably 40% or more.

  It is desirable that the first coil portion 311 and the second coil portion 312 satisfy a coil pitch of 120 to 180%. If the temperature is outside this range, the filament temperature is too high or too low to be practical as a tubular heater. Moreover, it is desirable that the main portion 31 does not include a coil region that satisfies a coil pitch of 200% or more. That is, as shown in FIG. 4, the main portion 31 does not have a portion where B3 / A3, which is a relationship between the diameter A3 (mm) of the metal wire and the distance B3 (mm) between adjacent coil portions, is 2 or more. Is desirable. However, a portion where the coil pitch satisfies 200% or more against the intention of the designer due to manufacturing variation or the like is excluded. The coil pitch as described above is such that the length L1 at which the main portion 31 is disposed is 150 to 250 mm, the inner diameter r of the glass tube 1 is 3.5 mm or less, and the diameter of the metal wire constituting the filament 3 is 0. It is desirable to apply in the case of 25 mm or more and lamp power of 800 W or more.

  Furthermore, the distance D1 between the adjacent support members 4 is desirably 8 mm or less. This is because the densely wound first coil portion 311 has a high temperature and is easily bent during lighting. In addition, the boundary between the first coil portion 311 and the second coil portion 312 is arranged so as to be positioned at the approximate center between the adjacent support members 4, particularly between the adjacent support members 4, and is not held. It is desirable to do so. The boundary between the first coil portion 311 and the second coil portion 312 can have a predetermined coil pitch difference with almost no change region, and by not holding the portion with the support member 4 This is because a relatively steep change in light distribution can be obtained.

In the first embodiment, P / V ≧ 0.44 W / mm ³ , where P (W) is the lamp power and V (mm ³ ) is the volume of the space 13 where the main portion 31 is disposed. Even with a high-load and compact tubular heater that satisfies the requirements, the coil pitch of the first coil portion 311 is configured to be 20% or more smaller than the coil pitch of the second coil portion 312, and has a characteristic arrangement. Light can be obtained.

  In addition, the boundary between the first coil portion 311 and the second coil portion 312 is disposed between the adjacent support members 4 and is not held by the support member 4. The change in the light distribution of the second coil unit 312 can be made steep.

(Second Embodiment)
FIG. 5 is a diagram for explaining the fixing device according to the second embodiment. About each part of this 2nd Embodiment, the same part as each part of the tubular heater of 1st Embodiment is shown with the same code | symbol, and the description is abbreviate | omitted.

  The fixing device includes a tubular heater 100, a fixing roller 200, and a pressure roller 300.

  The tubular heater 100 is the heater described in the first embodiment.

  The fixing roller 200 is a roller for fixing the toner transferred onto the paper surface to the copy paper P and for conveying the copy paper P by rotating. The fixing roller 200 has, for example, a three-layer structure including a metal layer made of stainless steel, an elastic layer made of silicon rubber, and a resin layer, and both ends thereof are open. The center of the fixing roller 200, that is, the inside of the metal layer is hollow, and the tubular heater 100 is disposed therein as shown in FIG.

  The pressure roller 300 is a roller for applying pressure to the copy paper P to sandwich the copy paper P together with the fixing roller 200 and fixing the toner transferred onto the paper surface to the copy paper P. The pressure roller 300 also has a three-layer structure similar to that of the fixing roller 200 and is open at both ends. The tubular heater 100 is also disposed in a cavity formed inside the pressure roller 300.

  Even when the tubular heater 100 is disposed on the fixing roller 200 or the pressure roller 300 where the temperature tends to decrease at both ends during lighting because the both ends are open as in this embodiment, the temperature decrease is eliminated. In addition, the surface temperature of the roller in the tube axis direction can be made uniform. Further, the distance D2 between the outer surface of the tubular portion 11 of the tubular heater 100 and the inner surface of the fixing roller 200 or the pressure roller 300 is 5 mm or less, which is shorter than the conventional one, and the surface temperature in the tube axis direction of the roller is the tubular heater 100. Even if it comes to be influenced by this light distribution, if it is the tubular heater 100 of this embodiment, the surface temperature can be equalized.

  The present invention is not limited to the above embodiments, and various modifications are possible. For example, it is good also as a design which makes the light distribution near the center of a tubular heater stronger than others by forming the 1st coil part 311 in the center part of a pipe-axis direction. Moreover, you may provide the 3rd coil part from which the coil pitch differs from the 1st coil part 311 and the 2nd coil part 312. That is, there may be a region where there are two or more light distribution changes in the tube axis direction of the heater.

  Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Glass tube 2 Metal foil 3 Filament 31 Main part 311 1st coil part 312 2nd coil part 32 Leg part 4 Support member

Claims (2)

A long glass tube with a space inside, a metal foil sealed at both ends of the glass tube, and a main part, connected to the metal foil so that the main part is arranged in the space A filament heater, and a plurality of support members provided along the tube axis direction in the glass tube and holding the main part ,
When the lamp power is P (W) and the volume of the space where the main part is disposed is V (mm ³ ), P / V ≧ 0.44 W / mm ³ is satisfied,
The main portion includes a first coil portion and a second coil portion, the wire diameter of the coil metal wire is A (mm), the distance between adjacent coils is B (mm), and the coil pitch (%) is When (B / A) × 100, the first coil portion has a coil pitch of 20% or more smaller than the second coil portion ,
A tubular heater, wherein a boundary between the first coil portion and the second coil portion is disposed between the support members adjacent to each other .   The first coil portion and the second coil portion satisfy a coil pitch of 120 to 180%, and the main portion does not include a coil region that satisfies a coil pitch of 200% or more. The tubular heater according to claim 1.

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