JP7573241B2 - Infrared emitting device - Google Patents

Description

The present invention relates to an infrared radiation device that irradiates an object to be heated with infrared rays of only a specific wavelength range.

Conventionally, infrared emitting devices that emit infrared rays in a specific wavelength range have been known as heating devices that heat objects that have absorption characteristics in a specific wavelength range (see, for example, Patent Document 1).

Figure 4 is a schematic diagram of Patent Document 1. The configuration disclosed in Patent Document 1 is as follows:

In the infrared emitting device 101, a radiation part 102 having a characteristic of emitting infrared rays in a specific wavelength range is arranged in the internal space of a cylindrical outer tube 104 whose inner wall is made of a reflective layer 103. An emission part 105 is installed in the outer tube 104 for emitting infrared rays emitted from the radiation part 102 in the outer tube 104 to the outside of the outer tube 104. The emission part 105 is made of a material that transmits infrared rays, and emits infrared rays incident from an entrance surface 105a located on the inside of the outer tube 104 among the outer peripheral surfaces of the emission part 105 from an exit surface 105b located on the opposite side to the entrance surface 105a of the emission part 105. In the exit part 105, infrared rays are totally reflected inward on the outer peripheral surfaces other than the entrance surface 105a and the exit surface 105b, so that the infrared rays incident from the entrance surface 105a are guided to the exit surface 105b. Therefore, infrared rays in a specific wavelength range emitted from the radiation unit 102 reach the incident surface 105a of the emission unit 105 directly, or are reflected by the reflective layer 103 in the outer tube 104. When they reach the incident surface 105a of the emission unit 105, they are guided by the emission unit 105 to the emission surface 105b, and emit infrared rays locally near the external emission surface 105b.

JP 2020-17433 A

However, in the configuration of Patent Document 1, the wavelength range of the infrared light emitted from the infrared emitting device cannot be changed, so it is necessary to create individual infrared emitting devices and attach them to heating equipment in accordance with materials with different absorption wavelength ranges, which increases costs and the burden on workers.

In view of these points, the present invention aims to provide an infrared emitting device that changes the wavelength range of the infrared light it emits.

In order to achieve the above object, an infrared emitting device according to one aspect of the present invention comprises:
An infrared emitting device that emits infrared rays,
a radiation unit having a radiation surface in which a wavelength range of the radiated infrared light changes depending on an angle between the radiation direction of the radiated infrared light and the radiation surface;
a housing having a hemispherical shape with an inner wall surface formed of a reflective layer, the housing having a first emission section disposed at a position of the center of the sphere and emitting the infrared rays, the emission section being disposed within a housing space with the emission surface of the emission section facing the first emission section;
and an angle adjustment unit that adjusts the angle of the radiation surface of the radiation unit with respect to the first emission unit of the housing.

As described above, according to the infrared emitting device of the above aspect of the present invention, the angle of the emitting surface of the emitting unit can be adjusted by the angle adjustment unit to accommodate the absorption wavelength ranges of multiple materials, thereby reducing the manufacturing costs of the infrared emitting device to accommodate materials with different absorption wavelength ranges and the burden on the worker of replacing it with heating equipment.

FIG. 1 is a schematic configuration diagram of an infrared emitting device according to a first embodiment of the present invention, as viewed from the side; FIG. 1 is a schematic front view of an infrared emitting device according to a first embodiment of the present invention; FIG. 2 is a partially enlarged schematic side view of the infrared emitting device according to the first embodiment of the present invention, for explaining the radiation angle α on the radiation surface; FIG. 1 is a diagram showing the emissivity spectrum of infrared rays emitted at a radiation angle of 10° on a radiation surface. A diagram showing the relationship between the emissivity spectrum and radiation angle for a radiation surface in which the wavelength range of infrared radiation changes depending on the radiation angle. FIG. 1 is a schematic diagram of an infrared emitting device according to a second embodiment of the present invention; Schematic diagram of a conventional infrared emitting device

The following describes an embodiment of the present invention with reference to the drawings.

Figures 1A and 1B are schematic diagrams of the infrared emitting device 1 according to the first embodiment of the present invention, seen from the side and the front, respectively.

The infrared emitting device 1 includes at least a housing 3, a radiation unit 2, and an angle adjustment unit 5, and emits infrared rays 20. The infrared emitting device 1 further includes an output control unit 10 and an angle adjustment control unit 6.

The housing 3 has a hemispherical shape with the inner wall surface covered with a reflective layer 4 such as a mirror surface, and the circular flat radiation part 2 is disposed on a line 3c connecting the center 3a and the apex 3b of the hemispherical housing space 3d. The reflective layer 4 is made of a metal such as Au, Ag, Cu, or mirror-polished SUS.
The radiating section 2 is heated by the power supplied by the output control section 10 and radiates infrared rays 20 from its surface.

The housing 3 is provided with a circular flat first emission section 7 that transmits infrared rays 20 at the position of the spherical center 3a, with the central axis along the line 3c. The emission section 2 is disposed in the housing space 3d of the housing 3 with the emission surface 9 of the emission section 2 facing the first emission section 7. The first emission section 7 is formed of a material that has high transparency in the infrared region from ultraviolet to around 10 μm, such as CaF ₂ , BaF ₂ , MgF ₂ , or SiO ₂ . Therefore, the infrared rays 20 emitted from the emission section 2 and reaching the first emission section 7 are emitted from the first emission section 7 to the outside of the housing 3 along the extension line of the line 3c, and are irradiated to the workpiece 8 as the heated object. The surface of the radiation unit 2 facing the first emission unit 7 has a radiation surface 9 which emits infrared rays 20 in a specific wavelength range, and the wavelength range of the emitted infrared rays 20 changes depending on the angle α between the radiation direction of the infrared rays 20 and the radiation surface 9, as will be described in detail later. The surfaces of the radiation unit 2 other than the radiation surface 9 may be made of any material, but are preferably made of a material with low emissivity. Examples of materials with low emissivity include metals such as Au, Ag, Cu, W, and Mo.
The angle adjustment unit 5 is connected to the radiation unit 2 so that the angle α between the radiation direction of the infrared rays 20 and the radiation surface 9, that is, the angle α of the radiation surface 9 of the infrared rays 20 with respect to the plane parallel to the incident surface 7a of the first emission unit 7, can be adjusted. When the angle α when the radiation surface 9 is parallel to the plane parallel to the incident surface 7a of the first emission unit 7 is set to 0°, the angle α of the radiation surface 9 can be adjusted to any angle between -80° and 80°, for example, by the angle adjustment control unit 6 that controls the angle adjustment unit 5. When the angle α of the radiation surface 9 is 80° to 90° (excluding 80°) or -80° to -90° (excluding -80°), the change in the wavelength region of the radiated infrared rays 20 is small, at a few percent or less. Therefore, if the angle α of the radiation surface 9 is in the range of -80° to 80°, the change characteristic of the wavelength region at the angle of the radiation surface 9 can be fully utilized.
Two SUS rods are used as an example of the angle adjustment unit 5. On the rear surface of the radiation unit 2, the ends of the two rods are attached to both ends of the radiation unit 2 on a line that passes through the midpoint of the radiation unit 2 and is perpendicular to the rotation axis of the radiation unit 2, so that the rods are perpendicular to the radiation surface 9. When changing the angle α, one of the two rods is moved toward the emission unit 7 and the other rod is moved in the direction opposite to the emission unit 7 by an equal distance at the same time, thereby allowing the angle α to be arbitrarily adjusted.
As an example of the angle adjustment control unit 6, a plate of the same size as the radiation unit 2 is attached to each end of two rods (angle adjustment units 5) opposite the radiation unit 2 so as to be parallel to the radiation unit 2. A rotation mechanism is provided on the plate so that the angle of the plate can be changed in the same rotation direction as the angle α. Since the radiation unit 2 and the plate are connected by the angle adjustment units 5, which are two rods, the angle of the plate can be adjusted arbitrarily, and therefore the angle α of the radiation unit 2 can also be adjusted in the same way.
The diameter of the radiation unit 2 is set to a length that does not interfere with the housing 3 when the angle α of the radiation unit 2 is changed by the angle adjustment unit 5. The diameter of the first emission unit 7 is set to be equal to or less than the length of the minor axis of an ellipse that is projected onto a plane parallel to the incident surface 7a of the first emission unit 7 when the radiation unit 2 is tilted by an angle at which the absolute value of the angle α is maximized with respect to a plane parallel to the incident surface 7a of the first emission unit 7, that is, when tilted by ±80° in this first embodiment.

In the first embodiment, the shape of each of the radiation unit 2 and the first emission unit 7 is circular as an example, but they may be square or rectangular. The length of each side of the radiation unit 2 is set to a length that does not interfere with the housing 3 when the angle α of the radiation unit 2 is changed by the angle adjustment unit 5. As in the case of a circular shape, the length of each side of the first emission unit 7 is set to be equal to or less than the length of the side corresponding to each projected portion onto a plane parallel to the incidence surface 7a of the first emission unit 7 when the radiation unit 2 is tilted by an angle at which the absolute value of the angle α is maximum with respect to a plane parallel to the incidence surface 7a of the first emission unit 7, that is, when tilted by ±80° in the first embodiment.

The maximum angle α to which the radiation unit 2 can be adjusted by the angle adjustment unit 5 is set in consideration of the characteristics of the infrared rays 20 emitted from the radiation surface 9 or the size of the radiation unit 2, etc.

Here, the details of the radiation unit 2 that radiates infrared rays 20 in a specific wavelength range will be described. The wavelength distribution of infrared rays 20 radiated from a general infrared radiator is determined by the product of the thermal radiation spectrum of a perfect black body, which is uniquely determined by absolute temperature according to Planck's law, and the inherent emissivity spectrum of the material of the heat generating part of the infrared radiator, which is made of metal or dielectric. The thermal radiation spectrum of a perfect black body shows a broad wavelength distribution, and the emissivity spectrum of a material also shows a distribution biased to a specific wavelength depending on the material, but it was difficult to radiate infrared rays with a wavelength distribution that has a narrow band peak similar to the absorption wavelength of the functional group of the molecule that constitutes a specific material. However, in recent years, research has been actively conducted on microfabricating the surface structure of the heat generating part to control the emissivity spectrum. Structures used for emissivity control include a structure in which metal holes or protrusions are periodically arranged in a two-dimensional plane on two thin layers of metal and dielectric, or a laminated structure in which two types of dielectrics with different refractive indices are alternately stacked on a metal layer. In this way, by designing the microstructure of the surface of the heat generating part of the infrared radiator, it is possible to emit infrared rays 20 with a wavelength distribution that has a peak in a narrow band at any wavelength.

Furthermore, there is a microstructure that has the characteristic that the wavelength range of the radiated infrared rays 20 changes depending on the radiation angle α at the radiation surface 9, which has a microstructure applied to its surface so as to radiate infrared rays 20 in the specific wavelength range described above.

FIG. 2A shows a simulation analysis of infrared radiation emitted in a direction tilted by 10° from a direction perpendicular to the radiation surface 9 of a certain multilayer structure in which two types of dielectrics are alternately laminated on a metal layer.
1 is a graph of an emissivity spectrum. It can be seen that there is a peak showing high emissivity near a wavelength of 3.3 μm, and that the material has the characteristic of emitting infrared rays in a specific wavelength range. The metal layer of the multilayer structure is formed of a metal such as Au, Ag, Cu, W, or Mo, and the film thickness is set to about 100 to 500 nm. The two types of dielectric materials of the multilayer structure are selected from Si, Ge, SiO ₂ , TiO ₂ , Al ₂ O ₃ , HfO ₂ , or SiC, and the film thickness of each is set to between about 100 nm and several μm.

Figure 2B is a contour diagram of the same multilayer structure, with the horizontal axis representing the wavelength of the infrared radiation, the vertical axis representing the radiation angle α of the infrared radiation, and the infrared emissivity represented by light and dark.

As can be seen from FIG. 2B , as the radiation angle α with respect to the radiation surface 9 changes from 0° to 90°, the position of the peak emissivity shown in FIG. 2A , which is the wavelength region of the infrared rays 20 radiated from the radiation surface 9 in the direction of the exit portion 7, shifts from the long wavelength side to the short wavelength side.
In this way, in the radiation section 2 having the radiation surface 9 in which the wavelength range of infrared rays changes depending on the radiation angle α, by adjusting the angle α of the radiation surface 9 relative to the plane of the incident surface 7a of the first emission section 7 using the angle adjustment section 5, infrared rays 20 in any wavelength range can be emitted from the first emission section 7.

Infrared rays that are emitted from the radiation unit 2, do not exit from the first emission unit 7, and are reflected by the reflective layer 4 are multiple-reflected within the housing 3 and are absorbed again by the radiation unit 2, so that they can be confined to a certain extent within the housing 3, improving the efficiency of infrared utilization.

According to the first embodiment, the angle α of the radiation surface 9 of the radiation unit 2 is adjusted by the angle adjustment unit 5 under the control of the angle adjustment control unit 6, thereby making it possible to accommodate the absorption wavelength ranges of a plurality of materials, thereby reducing the manufacturing costs of an infrared radiation device for accommodating materials with different absorption wavelength ranges and the burden on workers of replacing the device with heating equipment.
FIG. 3 is a diagram showing the configuration of an infrared emitting device 1 according to a second embodiment of the present invention.

In the second embodiment, the infrared emitting device 1 of the first embodiment further includes a hemispherical reflective member 11 whose inner wall surface is formed of a reflective layer 12 such as a mirror surface, and which is arranged symmetrically with respect to the plane 3e of the hemispherical housing 3.

The reflecting member 11 has a second emission section 13 that has an incident surface 13a parallel to the incident surface 7a of the first emission section 7 of the housing 3 and that passes infrared rays, located at a position facing the first emission section 7 on the extension of the line 3c. The infrared rays that are emitted from the radiation section 2, pass through the first emission section 7, and reach the second emission section 13 are emitted outside the reflecting member 11 through the second emission section 13. The second emission section 13 is made of a material that transmits the infrared rays that have passed through the emission section 7, or has an entrance as an incident surface and opens through it.

According to the second embodiment, in addition to the effects of the first embodiment, the following effects can be achieved. That is, a part of the infrared rays emitted from the radiation surface 9 of the radiation unit 2 and passing through the first emission unit 7 reaches the second emission unit 13, is emitted from the second emission unit 13, and is irradiated to the workpiece 8. The infrared rays that enter the first emission unit 7 at an angle to the line 3c, not along the line 3c, and pass through the first emission unit 7 but do not head toward the second emission unit 13 are reflected by the reflective layer 12 of the reflecting member 11, are multiple-reflected within the reflecting member 11 or the housing 3, and are partially absorbed by the radiation unit 2, so that they can be confined to a certain extent. In this way, the infrared rays emitted at an angle along the direction connecting the radiation surface 9, the first emission unit 7, and the second emission unit 13 can be locally irradiated below the second emission unit 13.

In addition, by appropriately combining any of the various embodiments or modifications described above, it is possible to achieve the effects of each. In addition, it is possible to combine embodiments with each other, or to combine examples with each other, and it is also possible to combine features of different embodiments or examples.

The infrared radiation device according to the above aspect of the present invention can heat the object to be heated by emitting infrared rays with wavelengths that match materials having various absorption wavelength ranges, so that the desired heat treatment can be performed at low cost and with high efficiency. Therefore, the infrared radiation device according to the above aspect of the present invention can be applied as a highly efficient heating device to heat treatment devices that perform various heat treatments, such as drying furnaces, baking furnaces, curing furnaces, and reflow furnaces, in the manufacturing process of industrial products or home appliances, or in the manufacturing process of various electronic components.

Reference Signs List 1 Infrared emitting device 2 Radiation section 3 Housing 3a Center of sphere 3b Vertex 3c Line connecting the center of sphere and the vertex 3d Housing space 3e Plane 4 Reflection layer 5 Angle adjustment section 6 Angle adjustment control section 7 First emission section 7a Incident surface 8 Work 9 Radiation surface 10 Output control section 11 Reflection member 12 Reflection layer 13 Second emission section 13a Incident surface 20 Infrared ray 101 Infrared emitting device 102 Radiation section 103 Reflection layer 104 Outer tube 105 Emission section 105a Incident surface 105b Emission surface α Angle between the emission surface and the incident surface of the emission section

Claims (2)

An infrared emitting device that emits infrared rays,
a radiation unit having a radiation surface in which a wavelength range of the radiated infrared light changes depending on an angle between the radiation direction of the radiated infrared light and the radiation surface;
a housing having a hemispherical shape with an inner wall surface formed of a reflective layer, the housing having a first emission section disposed at a position of the center of the sphere and emitting the infrared rays, the emission section being disposed within a housing space with the emission surface of the emission section facing the first emission section;
an angle adjustment unit that adjusts the angle of the radiation surface of the radiation unit with respect to the first emission unit of the housing. The infrared radiation device according to claim 1, further comprising a hemispherical reflecting member whose inner wall surface is made of a reflecting layer and arranged in plane symmetry with respect to the plane of the hemispherical housing, and a second emission section having an entrance surface parallel to the entrance surface of the first emission section of the housing, at a position facing the first emission section of the reflecting member.

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