Patent Application
20180255612
The present invention relates to a planar heater, for example, a planar heater in which a carbon wire heat generator is housed in a quartz glass tube.
Japanese Unexamined Patent Application Publication No. 2001-332373 discloses a planar heater 60 as illustrated in
A groove-like space (not shown) is formed inside the quartz glass support member 61, and a carbon wire heat generator W is wired in the groove-like space in a zigzag pattern shape. Sealing terminals (not shown) are connected to both ends of the carbon wire heat generator W, respectively, and an inert gas is injected and sealed in the space.
Further, the quartz glass support member 61 has a structure that is integratedly fused except for the groove-like space.
The carbon wire heat generator disclosed in Japanese Unexamined Patent Application Publication No. 2001-332373 is smaller heat capacity than a metal heat generator or the like and has better temperature rise/fall characteristics, and also has better high-temperature durability in a non-oxidizing atmosphere. In addition, because the carbon wire heat generator is manufactured by knitting a plurality of thin carbon single fiber bundles, there are advantages in which the carbon wire heat generator has improved shape flexibility compared to a heat generator made of solid carbon material and can be easily manufactured into various structures and shapes.
Therefore, a heater in which the heat generator is enclosed together with a non-oxidizing gas in a clean heat-resistant support member such as a high-purity quartz glass member does not generate particles or the like and is extremely suitable as a heater for manufacturing semiconductors.
Incidentally, in a planar heater 60 illustrated in
As a solution of the aforementioned problem, for example, as illustrated in
With such a configuration of the heater, because the heat capacity of the quartz glass tube 81 with the carbon wire heat generator W housed therein is small, there is no problem such as deterioration of the responsiveness of the temperature rise and fall.
Incidentally, in a case where the carbon wire heat generator W is housed in the quartz glass tube 81 curved in an arc shape as in the heater structure illustrated in
However, when the carbon wire heat generator W and the quartz glass tube 81 are brought into contact with each other, the glass temperature rises and the glass reacts with carbon. Accordingly, the carbon wire breaks; the resistance value of the carbon wire changes; and local heat generation occurs. As a result, there arises a problem of promoting deterioration of the carbon wire heat generator W and of causing the carbon wire heat generator to be liable to break (service life decreases).
Further, when the carbon wire heat generator W is brought into contact with the quartz glass tube 81, the heat from the carbon wire heat generator W is absorbed by the quartz glass tube 81 and the temperature of the heat generator is lowered, which causes deterioration of the heating efficiency of radiant heating.
The present invention has been made to solve the aforementioned technical problems, and an object thereof is to provide a planar heater wherein a carbon wire heat generator is housed in a long housing portion made of quartz glass; disconnection of the carbon wire heat generator is suppressed by limiting a contact region between the carbon wire heat generator and the long housing portion, and efficient radiation heating is achieved.
In order to solve the above issue, a planar heater according to the present invention is a planar heater in which a carbon wire heat generator is housed in a long housing portion made of quartz glass; the plurality of long housing portions is disposed on the same plane, and heat is generated by the energized carbon wire heat generator, wherein each of the plurality of long housing portions is formed in a polygonal circular arc shape in which a plurality of linear portions is connected to each other at a bent portion, respectively, and the plurality of long housing portions is disposed along circumferences of a plurality of concentric circles.
It is preferable that an intersection angle between the linear portions connected to each other at the bent portion in the long housing portion is 135° or larger and 170° or smaller.
Further, it is preferable that a polygonal circular shape is formed by at least one of the long housing portions, and the polygonal circular shape is disposed in a plurality of concentric circular shape.
Further, it is preferable that the long housing portion is made of a quartz glass tube, or the long housing portion may be a groove portion formed on the quartz glass plate.
According to the above configuration, when the carbon wire heat generator generates heat, deterioration of the carbon wire progresses at certain portions of the carbon wire heat generator, which is liable to come into contact with the bent portion of the long housing portion, but other portions are in a state of being hard to be deteriorated. That is, by restricting the contact region, it is possible to suppress progress of deterioration of the carbon wire as a whole.
Further, because the linear portion of the long housing portion has a configuration which is hard to come into contact with the carbon wire heat generator, heat from the carbon wire heat generator is not absorbed by the long housing portion, the heat generator temperature is maintained, and efficient radiation heating can be performed.
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As illustrated in
On a lower surface (back surface) side of the support base 2, a plurality of linear terminal portions 4 is wired, only four of which are shown in
A heater portion 10 is provided on the support base 2. The heater portion 10 has a quartz glass tube 11 (a long housing portion) as a protective tube, and a carbon wire heat generator W (see
Further, as a basic structure of the carbon wire heat generators W housed in the quartz glass tube 11, carbon wires are used, which are knitted into a knitting string shape having a diameter of about 2 mm or a knitted shape, using approximately ten fiber bundles prepared by bundling 3,000 to 3,500 long carbon fibers, having a diameter of 2 to 15 μm approximately, a diameter of 7 μm, for example. In the aforementioned case, the knitting span of the wire is approximately 2 to 5 mm.
As shown in
Further, both ends of the carbon wire heat generator W housed inside each quartz glass tube 11 are connected to the terminal portion 4, respectively.
The terminal portion 4 has a structure in which one end of a connection line (not shown) of made of a carbon wire that is housed in the quartz glass tube is connected to the carbon wire heat generator W, and the other end is connected to a metal power supply terminal (not shown). That is, the carbon wire heat generator W generates heat when the carbon wire heat generator W is energized from the power supply terminal via the connection line.
As described above, the quartz glass tube 11 has a linear portion 11a and a bent portion 11b. As shown in
In the quartz glass tube 11, an intersection angle θ of the linear portions 11a on both sides of the bent portion 11b is 135° or larger and 170° or smaller, and the length L of each linear portion 11a is 60 mm or longer. This is because, when the intersection angle θ is less than 135°, the carbon wire heat generator W strongly comes into contact with the tube inner side portion of the bent portion 11b in the quartz glass tube 11, the temperature of the quartz glass tube 11 is liable to rise, and the reaction of the carbon wire heat generator W to be accelerated. Further, when the intersection angle θ is less than 135°, it is difficult to uniformly and at high density dispose the carbon wire heat generators in the plane, and it fails to uniformly heat the object.
On the other hand, when the intersection angle θ exceeds 170° or when the length L of each linear portion 11a is less than 60 cm, the contact region between the quartz glass tube 11 and the carbon wire heat generator W increases, which is the same as the conventional configuration illustrated in
According to the planar heater 1 configured as described above, when the carbon wire heat generator W generates heat, the deterioration of the carbon wire progresses at a predetermined part of the carbon wire heat generator W that comes into contact with the bent portion 11b of the quartz glass tube 11. However, in other parts where the carbon wire is hard to come into contact with the linear portion 11a, the carbon wire is in a state of being hard to be deteriorated. That is, by restricting the contact region, it is possible to suppress the progress of deterioration of the carbon wire as a whole.
Further, since the linear portion 11a of the quartz glass tube 11 has a configuration that is hard to come into contact with the carbon wire heat generator W, the heat from the carbon wire heat generator W is not absorbed by the quartz glass tube 11; the temperature of the heat generator is maintained, and the efficient radiant heating can be performed.
In the aforementioned embodiment, as illustrated in
Further, in the aforementioned embodiment, one circle (polygonal circle) is formed by at least one quartz glass tube 11, and the circle is arranged in the shape of a plurality of concentric circles.
However, the present invention is not limited to the configuration, a substantially complete circle (polygonal circle) may not be formed by the quartz glass tube 11, and the quartz glass tube 11 may be partially disposed along the circumferences of a plurality of concentric circles. In this case, for example, for a portion in which the quartz glass tube 11 is not disposed along the circumference, the quartz glass tube 11 is disposed to achieve uniform radiation heating as a whole heater on a concentric circle having a larger diameter or a concentric circle having a smaller diameter.
Further, in the aforementioned embodiment, the quartz glass tube 11 has been described as an example of a long housing portion made of quartz glass, but the planar heater according to the present invention is not limited to that form.
For example, as illustrated in
Further, in
The planar heater according to the present invention will be further illustrated based on examples. In the examples, the disconnection test of the carbon wire heat generator was performed using the planar heater described in the above embodiment, and the effect of the present invention was verified.
In a first example, the planar heater having the configuration of the present invention illustrated in
In a second example, the intersection angle between the linear portions at the bent portion in the quartz glass tube of the heater portion was set to 110°. Other conditions are the same as those of the first example.
In a third example, the intersection angle between the linear portions at the bent portion in the quartz glass tube of the heater portion was set to 135°. Other conditions are the same as those of the first example.
In a fourth example, the intersection angle between linear portions at the bent portion in the quartz glass tube of the heater portion was set to 170°. Other conditions are the same as those of the first example.
In a fifth example, the intersection angle between the linear portions at the bent portion in the quartz glass tube of the heater portion was set to 175°. Other conditions are the same as those of the first example.
In a first comparative example, as illustrated in FIG. 9, a planar heater in which the carbon wire heat generator is curved along an arc-shaped quartz glass tube was used, and the time until the disconnection of the carbon wire heat generator by applying a current of 33 A was measured.
The results of this test are summarized in Table I. As illustrated in Table I, the time until the disconnection of the carbon wire heat generator became longer in a range in which the intersection angle between the linear portions of the quartz glass tube is 135° or larger and 170° or smaller (first, third and fourth examples), and in other ranges (second and fifth examples) and the first comparative example, a shorter result was obtained.
When the intersection angle is set to 110°, because the carbon wire heat generator and the quartz glass tube strongly come into contact with each other at the bent portion, the temperature of the quartz glass tube rises, the reaction with the carbon wire heat generator is accelerated, and the disconnection of the carbon wire heat generator is considered to be accelerated.
Further, when the intersection angle is set to 175°, since the planar heater is substantially circular and accordingly, the contact region between the quartz glass tube and the carbon w ire heat generator increases, the temperature of the quartz glass tube rises; the reaction with the carbon wire heat generator accelerates, and the disconnection of the carbon wire heat generator is considered to be accelerated.
From the results of the above examples, according to the planar heater of the present invention, it was confirmed that the breakage of the carbon wire heat generator can be suppressed by limiting the contact region between the carbon wire heat generator and the long housing portion made of quartz glass.
