Plane heater

Abstract

To provide a planar heater capable of being used at a high temperature more simply and inexpensively without arranging fine ceramics in a heater portion.SOLUTION: A planar heater according to an embodiment of the present invention includes a thin-film heating element, a heater unit having an upper crystallized glass plate and a lower crystallized glass plate sandwiching the thin-film heating element, and a metal case that supports the heater unit. Also, the upper crystallized glass plate and the lower crystallized glass plate are fixed by a plurality of elastic claw members in order to adjust the difference in thermal expansion coefficient.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sheet heater. [Background technology]

[0002] Plane heaters are used in the heating process of industrial products. Conventionally, the performance of these planar heaters has been governed by the heat resistance and electrical insulation of the insulating material, with mica being the most commonly used insulating material.

[0003] However, the heat resistance temperature of mica is 600°C or less, and the maximum operating temperature for the heater is about 300°C, posing a problem when used at higher temperatures.

[0004] On the other hand, a technique for using fine ceramics as an insulating material is described in, for example, Patent Document 1 below. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2004-79504 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, ceramics such as those disclosed in Patent Document 1 are very expensive, and there is a problem that they cannot be easily used for any process other than special processes.

[0007] In view of the above problems, the present invention has an object to provide a sheet heater that can be used at high temperatures more simply and inexpensively without providing fine ceramics in the heater portion. [Means for solving the problem]

[0008] The planar heater according to one aspect of the present invention for solving the above problems includes a heater section having a thin-film heating element and an upper crystallized glass plate and a lower crystallized glass plate sandwiching the thin-film heating element therebetween. The thin-film heating element, the upper crystallized glass plate, and the lower crystallized glass plate are fixed to the metal case by a plurality of elastic claw members. This is what we have in mind.

[0010] In addition, in this respect, although not limited thereto, it is preferable that the lower crystallized glass plate is divided into a plurality of pieces.

[0011] In addition, in this respect, although not limited thereto, the upper and lower crystallized glass plates have a heat-resistant temperature of 950° C., and the W density of the heater part is 3.0 W / cm 2 More preferably, it is equal to or greater than this.

[0013] In addition, in this respect, although not limited thereto, it is preferable that at least one of the upper crystallized glass plate and the lower crystallized glass plate is made of recrystallized glass.

[0014] Also, in this respect, although not limited thereto, it is preferable that the metal case has a first case having a first contact portion that contacts and supports the lower crystallized glass plate at the peripheral portion of the lower crystallized glass plate and a first plate-shaped portion that forms a lower space in the center of the lower crystallized glass plate, and a second case having a second contact portion that contacts and supports the first case at the peripheral portion of the first plate-shaped portion of the first case, and a second plate-shaped portion that forms a lower space in the center of the first plate-shaped portion of the first case.

[0015] In addition, although not limited to this aspect, it is preferable that the claw portion is fixed to the metal case.

[0016] In addition, in this aspect, although not limited thereto, it is preferable to provide a mechanism for preventing the positional deviation of the thin film heating element between the upper crystallized glass plate and the lower crystallized glass plate. This mechanism for preventing the positional deviation is preferably provided with a hole formed in at least one of the upper crystallized glass plate and the lower crystallized glass plate, and a pin that is fitted into this hole. Effect of the Invention

[0017] As described above, the present invention makes it possible to provide a sheet heater which can be used at high temperatures more simply and inexpensively without providing fine ceramics in the heater portion. [Brief description of the drawings]

[0018] [Figure 1] 1 is a perspective view of a sheet heater according to an embodiment. [Diagram 2] FIG. 2 is a top view of the sheet heater according to the embodiment. [Diagram 3] FIG. 2 is a side view of the sheet heater according to the embodiment. [Figure 4] 1 is a cross-sectional view of a sheet heater according to an embodiment. [Diagram 5] FIG. 2 is an exploded perspective view of a heater portion of the sheet heater according to the embodiment. [Figure 6] 3 is a conceptual diagram of a cross-sectional structure of a heater part of a sheet heater according to an embodiment. FIG. [Figure 7] FIG. 2 is a top view of a thin-film heating element of the sheet heater according to the embodiment. [Figure 8] FIG. 2 is a diagram showing a divided state of a lower crystallized glass plate in a heater portion of a planar heater according to an embodiment. [Figure 9] FIG. 2 is a view showing a cross section of a part of a lower crystallized glass plate in a heater portion of a planar heater according to an embodiment. [Figure 10] FIG. 13 is a diagram showing an image of fixing a thin-film heating element by holes and pins in a lower crystallized glass plate according to an embodiment of the present invention. [Figure 11] 4A and 4B are diagrams illustrating an outline of a claw member in the sheet heater according to the embodiment. [Figure 12] 2 is a perspective view of the sheet heater according to the embodiment, seen from the rear side. FIG. [Figure 13] FIG. 4 is a perspective view of a metal case that supports a heater unit according to the embodiment. BEST MODE FOR CARRYING OUT THEINVENTION

[0019] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention can be embodied in many different forms, and the specific examples described in the following embodiments and examples can be appropriately modified and adjusted, and the present invention is not limited thereto.

[0020] Fig. 1 is a perspective view of a sheet heater (hereinafter referred to as "the heater") 1 according to this embodiment, Fig. 2 is a top view of the heater 1, and Fig. 3 is a side view of the heater 1. Also, Fig. 4 is a cross-sectional view of the heater 1.

[0021] As shown in these figures, the heater 1 has a heater section 2 and a metal case 3 that supports the heater section 2.

[0022] 5 is an exploded perspective view of the heater section 2 of the heater 1, and FIG. 6 shows an image of the cross-sectional structure of the heater section 2 of the heater 1. As shown in these figures, the heater section 2 has a thin-film heating element 21, and an upper crystallized glass plate 22 and a lower crystallized glass plate 23 that sandwich the thin-film heating element 21.

[0023] This configuration of the heater 1 makes it possible to use the heater at high temperatures more simply and inexpensively without using fine ceramics. In particular, the heater 1 is suitable for use in heating semiconductor substrates such as silicon wafers, and has a heat resistance of 800°C, preferably 950°C, and a power of 2.0 W / cm. 2 More than 3.0W / cm 2 It is possible to realize a density of the above or higher. The specific configuration and mechanism by which this effect is achieved will be specifically described below.

[0024] First, the heater section 2 of the heater 1 has a flat mounting surface 221, and the heating object is placed on the mounting surface, and the upper crystallized glass plate 22 is heated by applying electricity to the thin-film heating element 21, thereby making it possible to heat the heating object. As will be described later, the mounting surface 221 is one side of the upper crystallized glass plate 22.

[0025] The shape of the heater section 2 of the heater 1 is not limited as long as it has a flat mounting surface, but in order to ensure uniformity of temperature, it may be a polygonal shape such as a square or hexagon when viewed from above, but is preferably a circle. In the case of a circle, there is an advantage that it is easy to ensure uniformity of temperature because there are no corners that are necessarily provided in the case of a polygon. Of course, in the case of a polygon, there is an advantage that a large installation area can be secured even if the installation area of ​​the heater 1 is limited. In order to configure the shape of the heater section 2, the outer shape of the thin film heating element 21, the upper crystallized glass plate 22, and the lower glass plate 23 are of this shape.

[0026] As described above, the heater section 2 of the heater 1 has the thin-film heating element 21. The thin-film heating element 21 is literally a thin-film heating element that generates heat and makes it possible to control the temperature of the mounting surface by controlling the amount of heat generated. The heating element is not limited as long as it has this function, but it is preferable that the heating element has a conductive material and generates heat by passing electricity through the conductive material due to its electrical resistance. Figure 7 shows a top view of one example of the shape of the thin-film heating element 21.

[0027] Furthermore, the thin-film heating element 21 is not limited to any particular material as long as it has the above-mentioned functions, but may be made of metals such as copper, nichrome, platinum, etc., or ceramics such as carbon, silicon carbide, molybdenum disilicide, etc.

[0028] The thin-film heating element 21 is formed in a thin film and in a planar shape, and is arranged so as to minimize bias in the plane. In the example shown in the figure, a metal heating element is wound around the entire surface in a meandering manner to form multiple concentric circles. In the example shown in the figure, electricity is passed from one end point 211 to the other end point 212, which can promote heat generation due to the resistance of the wiring.

[0029] The thickness of the thin film heating element 21 is not particularly limited. However, if the thickness of the heating element 21 is large, there is a risk of the temperature becoming non-uniform, so it is preferable that the heating element 21 is as thin as possible, preferably at least 1 cm or less, and more preferably 5 mm or less.

[0030] As described above, the heater section 2 of the heater 1 is provided with an upper crystallized glass plate 22 and a lower crystallized glass plate 23, which act as a pair of crystallized glass plates to sandwich the thin-film heating element 21.

[0031] The upper crystallized glass plate 22 is literally a plate-shaped member made of crystallized glass. As described above, when the thin-film heating element 21 generates heat, the upper crystallized glass plate 22 transmits and diffuses the heat generated by the thin-film heating element 21, and can provide heat to the heating object placed on the placement surface 221. By using crystallized glass for the member constituting the placement surface, the heater 1 has excellent thermal shock resistance even against heat of 600°C or more, and can maintain insulation even at high temperatures. Crystallized glass is glass produced by precipitating crystals, and is not limited to this, but a preferred example is recrystallized glass produced by first producing normal glass and then reheating the glass to precipitate crystals.

[0032] Moreover, from the viewpoint of ensuring insulation even at high temperatures of 600° C. or more, it is preferable that the upper crystallized glass plate 22 of the heater 1 contains metal ions such as sodium at a certain level or less. At high temperatures, the movement of these metal ions in the glass becomes active, causing a rapid drop in insulation performance, so the content of metal ions is kept as low as possible, below a certain level, and it is most preferable to not contain metal ions such as sodium, thereby making it possible to maintain insulation performance even at high temperatures.

[0033] As described above, the upper crystallized glass plate 22 of the heater 1 is a flat plate having a contact surface 222 arranged on the upper part of the thin-film heating element 21 so as to contact the thin-film heating element 21, and a mounting surface 221 for mounting an object to be heated. This makes it possible to ensure contact between the thin-film heating element 21 and the object to be heated.

[0034] The thickness of the upper crystallized glass plate 22 of the heater 1 is determined by taking into consideration the balance between the fact that it is preferable for the plate to have a certain thickness in order to ensure that the heat supplied from the thin-film heating element 21 is uniform over the surface, and that it is preferable for the plate to be as thin as possible in order to suppress heat loss. The thickness varies greatly depending on the material used, but is preferably 5 mm or more and 3 cm or less, for example.

[0035] In addition, the heater part 2 of this heater 1 is provided with a lower crystallized glass plate 23 as described above. The material, shape, thickness, etc. of the lower crystallized glass plate 23 can be almost the same as those of the upper crystallized glass plate 22, so the description of the same parts is omitted and the different points are mainly described. Note that, like the upper crystallized glass plate 22, the lower crystallized glass plate 23 is preferably recrystallized glass.

[0036] As is clear from the above description, the lower crystallized glass plate 23 in the heater section 2 of this heater 1 is a member for supporting the thin-film heating element 21, and by using this heat-resistant crystallized glass also below the thin-film heating element 21, it is possible to ensure heat resistance.

[0037] The lower crystallized glass plate 23 is significantly different from the upper crystallized glass plate 22 in that it is divided into a plurality of parts. The divided state of the lower crystallized glass plate 23 is shown in FIG. 8. In this heater 1, the lower crystallized glass plate 23 is divided into a plurality of parts, more specifically, into a circular part 231 near the center and a hollow circular part 232 that covers this central circle, and this hollow circular part 232 is further divided into two sector parts 2321 and 2322 so that they have the same shape. In this way, even if a sudden temperature difference occurs, it is possible to prevent the lower crystallized glass plate 23 from being damaged by thermal expansion and thermal contraction. It is preferable that each of these divided parts is supported by a metal case described later, but for example, the circular part 231 near the center is located in a position where it is difficult to support due to structure. 9, by providing a step-like difference on the side of the circular portion 232 and providing corresponding step-like differences in other portions (e.g., sectoral portions 2321, 2322) of the lower crystallized glass plate 23 and combining them, it becomes possible to prevent the lower crystallized glass plate 23 from falling off. That is, by dividing the lower crystallized glass plate 23 into a plurality of portions and combining them with steps provided in each portion, it becomes possible to prevent the lower crystallized glass plate 23 from falling off while fully responding to expansion and contraction.

[0038] The lower crystallized glass plate 23 is provided with a through hole 233 for inserting and fixing a connecting member 25 for supplying electricity to the supported thin-film heating element 21. By inserting the conductive connecting member 25 into this through hole and connecting it to the thin-film heating element 21, a stable electrical connection can be ensured.

[0039] As is clear from the above figure, the upper crystallized glass plate 22 and the lower crystallized glass plate 23 are provided with a plurality of through holes 224, 234 that pass through them in common, and the thin film heating element 21 is also arranged in this portion so as not to overlap. By arranging these through holes 224, 234, it becomes possible to insert an actuating pin into the through holes 224, 234 so as to be able to slide, and further, by arranging an actuator (not shown) for moving the actuating pin up and down under the heater 1, it becomes possible to lift the actuating pin a little from the mounting surface of the heating object that is placed on the mounting surface. This makes it possible to easily remove the heating object.

[0040] In addition, the lower crystallized glass plate 23 is provided with a plurality of holes 235, which are recesses, and the pins P are fitted into the holes 225, 235, so that the movement of the thin-film heating element 21 due to expansion and contraction can be restricted. An image of this case is shown in FIG. 10. As shown in this figure, the holes 225, 235 are provided in the upper crystallized glass plate 22 and the lower crystallized glass plate 23, respectively, so that the pins can be inserted to prevent the thin-film heating element 21 from moving. By arranging these holes at a plurality of positions in the folded portion of the thin-film heating element 21, even if the thin-film heating element 21 thermally expands and contracts, the movement of the thin-film heating element 21 can be suppressed. That is, the holes 225, 235 and the pins P are combined to form a mechanism for preventing the position of the thin-film heating element 21 from shifting. The holes 225, 235 may be formed only in one of the upper and lower crystallized glass plates, but by providing them in both crystallized glass plates, the upper and lower crystallized glass plates themselves can be held so as not to shift. The hole 225 formed in the upper crystallized glass plate 22 and the hole 235 formed in the lower crystallized glass plate 23 are formed to match the diameter of the pin P, but it is preferable that the hole 225 formed in the upper crystallized glass plate 22 is formed larger than the hole 235 formed in the lower crystallized glass plate 23. In this way, the pin P is less likely to slip relative to the lower crystallized glass plate 23, while there is a space in the gap even if a force in a slipping direction acts between the upper crystallized glass plate 22 and the lower crystallized glass plate 23, making it difficult to transmit a force in a shearing direction to the pin P.

[0041] In addition, in the heater section 2 of the heater 1, the thin film heating element 21, the upper crystallized glass plate 22, and the lower crystallized glass plate 23 are preferably fixed by a plurality of elastic claw members 24. First, it is necessary to fix them by the claw members 24 in order to stably maintain the arrangement relationship, while the thin film heating element 21 expands due to heat, and the upper crystallized glass plate 22 and the lower crystallized glass plate 23 also expand due to heat, although not as much as the thin film heating element 21. Therefore, if they are fixed by a claw member that hardly deforms elastically, the claw member will be damaged, and it will be difficult to maintain the arrangement relationship. Therefore, by fixing them by a plurality of elastic claw members 24, there is an advantage that it is possible to stably respond to this thermal expansion. In order to "have elasticity", it is preferable to use a material with elasticity, and specifically, metal is preferable. By forming them from metal, it is possible to have appropriate hardness and fully respond to the deformation of the thin film heating element 21, the upper crystallized glass plate 22, and the lower crystallized glass plate 23. A perspective view of one example of this claw member is shown in FIG. 11.

[0042] It is preferable that the bent portion 241 of the claw member 24 is bent with a curvature smaller than the chamfering dimension of the corner of the upper crystallized glass plate 22. In this way, the possibility that the corner of the upper crystallized glass plate 22 will come into contact with the claw member 24 is extremely low, and it is possible to suppress cracks in the crystallized glass plate due to such contact.

[0043] In addition, the heater 1 includes a metal case 3 in addition to the heater section 2. The metal case 3 is used to stably support the heater section 2, and is not limited thereto. It is preferable that the metal case 3 includes a first case 31 having a first contact portion 311 that contacts and supports the lower crystallized glass plate 23 at the periphery of the lower crystallized glass plate 23, a first plate-shaped portion 312 that forms a lower space at the center of the lower crystallized glass plate 23, and a second case 32 having a second contact portion 321 that contacts and supports the first case 31 at the periphery of the first plate-shaped portion 312 of the first case 31, and a second plate-shaped portion 322 that forms a lower space at the center of the first plate-shaped portion 312 of the first case 31. A perspective view of the back of the heater is shown in FIG. 12. This figure is a view of a state in which the reflector 33 described below is omitted. The cross section of the heater 2 including the reflector 33 is as shown in FIG. 4 above.

[0044] First, as described above, the metal case 3 has the first case 31 and the second case 32. The first case 31 and the second case 32 not only support the heater part 2, but are also used to form a space below the lower crystallized glass plate 23. In the metal case 3, the first case 31 and the second case 32 are provided stepwise below the lower crystallized glass plate 23, thereby preventing a sudden change in temperature difference and enabling stable operation.

[0045] As described above, the first case 31 of the metal case 3 has the first contact portion 311 that contacts and supports the lower crystallized glass plate 23 at the peripheral portion of the lower crystallized glass plate 23, and the first plate-shaped portion 312 that forms a lower space in the center of the lower crystallized glass plate 23. This forms a first space. The first contact portion 311 is connected to rise approximately vertically from the first plate-shaped portion 312. A schematic perspective view of the first case 31 is shown in FIG. 13.

[0046] Furthermore, the metal case 3 is provided with a second case 32. The second case 32 has a second contact portion 321 that contacts and supports the first case 31 at the peripheral portion of the first plate-shaped portion 312 of the first case 31, and a second plate-shaped portion 322 that forms a lower space in the center of the first plate-shaped portion 312 of the first case 31. This forms a second space, making it possible to mitigate the transmission of temperature to the outside.

[0047] It is preferable that the metal case 3 further includes a reflector 33 that covers the entire side surface of the heater section 2 including the claw members 24. Providing this reflector 33 has the advantage of preventing heat from being released and escaping from the side surface.

[0048] As described above, the claw members 24 are preferably fixed to the metal case 3. More specifically, the claw members 24 are preferably connected to the first case 31. In this manner, the heater section 2 can be reliably fixed while also being stably fixed to the metal case 3. This connection can be made by using screws or the like.

[0049] As described above, the heater 1 is a planar heater that can be used at high temperatures more simply and inexpensively without providing fine ceramics in the heater portion. [Industrial Applicability]

[0050] The present invention has industrial applicability as a sheet heater.

Claims

1. a heater section including a thin-film heating element, an upper crystallized glass plate and a lower crystallized glass plate sandwiching the thin-film heating element therebetween, and a metal case supporting the heater section; The thin film heating element, the upper crystallized glass plate and the lower crystallized glass plate are fixed to the metal case by a plurality of elastic claw members.

2. 2. The sheet heater according to claim 1, wherein the lower crystallized glass plate is divided into a plurality of pieces.

3. The upper and lower crystallized glass plates have a heat-resistant temperature of 800° C. or higher, and the W density of the heater portion is 2.0 W / cm ２ 2. The sheet heater according to claim 1, wherein the sheet heater is a heater having the above structure.

4. 2. The planar heater according to claim 1, wherein at least one of the upper crystallized glass plate and the lower crystallized glass plate is made of recrystallized glass.

5. The metal case is a first case having a first contact portion that contacts and supports the lower crystallized glass plate at a peripheral portion of the lower crystallized glass plate, and a first plate-shaped portion that forms a lower space at a central portion of the lower crystallized glass plate; A surface heater as described in claim 1, comprising a second case having a second contact portion that contacts and supports the first case at the peripheral portion of the first plate-shaped portion of the first case, and a second plate-shaped portion that forms a lower space in the center of the first plate-shaped portion of the first case.

6. A surface heater as described in claim 1, wherein the claw member is fixed to the metal case.

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