heating lamp

Abstract

The present invention provides a heating lamp that can efficiently heat and dry materials that are expected to be used in the future and exhibit higher absorption characteristics for longer wavelength light compared to conventional materials, while also suppressing thermal damage to workpieces and equipment and reducing energy consumption. [Solution] The halogen lamp comprises a long-shaped light-emitting tube and a filament housed within the light-emitting tube, which emits first light emitted by the filament through the wall surface of the light-emitting tube, and a light-receiving heat-generating element that surrounds the light-emitting tube in the circumferential direction, which generates heat by absorbing the first light and emits second light whose peak intensity wavelength belongs to a longer wavelength side than that of the first light.

Description

Technical Field

[0001] The present invention relates to a heating lamp.

Background Art

[0002] Conventionally, in a printing apparatus, a halogen lamp may be used to dry toner or dye. Further, as a method for more efficiently drying toner or dye, a light source device has been proposed that irradiates a printed matter with light emitted from a halogen lamp and light whose peak wavelength belongs to a longer wavelength side with respect to the light (for example, see Patent Document 1 below).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The light source device described in Patent Document 1 above is an invention made by paying attention to the fact that the wavelength range of light suitable for drying conventional toner or dye is the near-infrared region, and the absorption wavelength range differs for each ink color. Here, the "light in the near-infrared region" is used with the intention of referring to light belonging to the range of wavelengths of 0.7 μm to 2.5 μm.

[0005] When the inventors of the present invention were researching and investigating a light source for drying toner or dye, they came across a new finding that inks for which light on the longer wavelength side than the near-infrared region is suitable for drying were being studied. Therefore, in view of the circumstances, the inventors of the present invention examined a light source that can emit light on the longer wavelength side than the near-infrared region. And, while repeatedly conducting various examinations on a light source for a printing apparatus that can emit light in a target wavelength band, the inventors of the present invention noticed that the following problems exist.

[0006] To efficiently dry toners and dyes, the printed material must be irradiated with light of a wavelength that has a high absorbance for the toner or dye at a relatively high intensity; otherwise, the process will be inefficient. Therefore, a light source that can emit light at or near the target wavelength, in which the intensity spectrum peaks, must be used. This principle applies not only to the drying of toners and dyes in printed materials, but also to heating and drying processes such as resin molding. For this reason, the processed materials, including printed materials, may collectively be referred to as "workpieces" below.

[0007] However, light sources that emit light with peak wavelengths longer than the near-infrared region are generally difficult to use for drying workpieces. Figure 9 is a graph plotting the relationship between the spectral density of radiation and the wavelength of blackbody radiation at different temperatures. The reason for this is that, as shown in Figure 9, the peak wavelength of electromagnetic waves emitted from a radiator shifts to shorter wavelengths as the temperature of the radiator increases (Wien's displacement law).

[0008] To illustrate with a specific example, as shown in Figure 9, a light source emitting light with a peak wavelength of 5 μm needs to have a temperature of approximately 500 K when lit, while a light source emitting light with a peak wavelength of 10 μm needs to have a temperature of approximately 300 K when lit.

[0009] Let's consider halogen lamps, which are often used as heating lamps. Halogen lamps require a halogen cycle to occur within the discharge tube, and the temperature during operation must be 250°C (approximately 523K) or higher. In other words, halogen lamps have difficulty emitting light whose peak wavelength belongs to the longer wavelength range than the near-infrared region.

[0010] Another possible method involves increasing the power supplied to the halogen lamp, even if not at the peak wavelength, to raise the intensity of light in the near-infrared region, as well as the intensity of light belonging to longer wavelengths than the near-infrared region, to the desired level. However, this method requires more power to operate the heating lamp than conventional methods, and may cause greater thermal damage to the workpiece, printing equipment, and components mounted on the light source unit.

[0011] In view of the above problems, the present invention aims to provide a heating lamp that can efficiently heat and dry materials that are expected to be used in the future and that exhibit higher absorption characteristics for longer wavelength light compared to conventional materials, while also suppressing thermal damage to workpieces and equipment and reducing energy consumption. [Means for solving the problem]

[0012] The heating lamp of the present invention A halogen lamp comprising a long discharge tube and a filament housed within the discharge tube, wherein the first light emitted by the filament is radiated through the wall surface of the discharge tube, The present invention is characterized by comprising a light-receiving heat-generating element that surrounds the light-emitting tube in the circumferential direction, which generates heat by absorbing the first light and emits a second light whose peak intensity wavelength belongs to a longer wavelength side than the first light.

[0013] When a halogen lamp is surrounded by a light-receiving heat-generating element, most of the primary light emitted from the halogen lamp is converted into secondary light, which is then irradiated onto the workpiece as heating light. In this configuration, since the light source does not emit secondary light, there is no need to worry about the temperature of the light source itself.

[0014] Furthermore, since the light-receiving heater emits the secondary light, if a higher intensity of secondary light is desired, it is simply a matter of adjusting the shape and size of the light-receiving heater, which is currently simpler than obtaining a light source that emits secondary light.

[0015] Conventional heating lamps employ a configuration in which a portion of the first light emitted from a halogen lamp or the like is irradiated onto the workpiece, for purposes such as matching the peak wavelength according to the absorption spectrum of the workpiece.

[0016] However, given the new challenge of irradiating with light that exists on the longer wavelength side, it is preferable, as in the present invention, that the light-emitting tube is housed inside the light-receiving heating element so that substantially only the second light is irradiated onto the workpiece.

[0017] The phrase "effectively only the second light is irradiated onto the workpiece" here is used to allow for the case where the light emitted from the halogen lamp travels towards the light-receiving heat-generating element, but passes through the element and is still irradiated as the first light. This is because it is thought that very little of the first light passes through without being absorbed by the light-receiving heat-generating element, and therefore the impact on the workpiece is extremely small.

[0018] In the above heating lamp, The light-receiving heating element may also comprise a cylindrical substrate that transmits the first light and a coating layer formed on the wall surface of the substrate that emits the second light upon receiving the first light.

[0019] In the above heating lamp, The light-receiving heating element is made of a material mainly composed of an inorganic material that emits the second light upon receiving the first light, and may be a material that does not substantially transmit the first light.

[0020] In this specification, "transmitting" means that the transmittance to the target light is 50% or more, and "substantially non-transmitting" means that the transmittance to the target light is less than 10%. Furthermore, in this specification, "main component" is used to refer to the material with the highest content.

[0021] The above heating lamp is When viewed in the direction along the tube axis of the light-emitting tube, the separation distance between the light-emitting tube of the halogen lamp and the light-receiving and heat-generating body may be configured to be larger than the outer diameter of the light-emitting tube.

[0022] As described above, the peak wavelength of the radiated light is correlated with the temperature of the radiator. Therefore, when attempting to irradiate the workpiece with the second light having a peak wavelength on the longer wavelength side at a higher illuminance, it is preferable that the temperature of the light-receiving and heat-generating body while the halogen lamp is lit is lower.

[0023] Here, the temperature of the light-receiving and heat-generating body while the halogen lamp is lit depends on the relationship between the total amount of the first light irradiated on the light-receiving and heat-generating body and the amount of heat released from the light-receiving and heat-generating body. And in order to lower the temperature of the light-receiving and heat-generating body while the halogen lamp is lit, it is considered effective to increase the surface area of the outer wall surface of the light-receiving and heat-generating body and decrease the amount of heat per unit area of the light-receiving and heat-generating body.

[0024] Therefore, with the above configuration, the heating lamp can reduce the temperature of the light-receiving and heat-generating body and emit the second light having a peak wavelength on the longer wavelength side.

[0025] In the above heating lamp, The halogen lamp may be provided with a first reflection film that reflects the first light on the wall surface of the light-emitting tube in a part of the circumferential direction centered on the tube axis of the light-emitting tube.

[0026] In the above heating lamp, The light-receiving and heat-generating body may be provided with a second reflection film that reflects the second light on the outer wall surface in a part of the circumferential direction.

[0027] With the above configuration, the first and second rays of light emitted to travel away from the workpiece can be reflected to travel towards the workpiece. Therefore, the heating lamp with the above configuration can irradiate the workpiece with the second rays at a higher illuminance. Furthermore, the configuration with the first reflective film has the advantage that the directivity of the first rays is enhanced, allowing for efficient heating of workpieces positioned in a predetermined direction relative to the heating lamp, and maintaining a lower temperature for the light-receiving heating element. In contrast, the configuration with the second reflective film has the advantage that the amount of light irradiated onto the discharge tube and filament of the halogen lamp is significantly reduced, thus having less impact on the lifespan of the halogen lamp. [Effects of the Invention]

[0028] According to the present invention, a heating lamp is realized that can efficiently heat and dry materials that are expected to be used in the future and that exhibit higher absorption characteristics for longer wavelength light compared to conventional materials, while also suppressing thermal damage to workpieces and equipment and reducing energy consumption. [Brief explanation of the drawing]

[0029] [Figure 1] This is a schematic overall perspective view showing one embodiment of a light irradiation device. [Figure 2] This is a cross-sectional view AA of the light source unit in Figure 1. [Figure 3] Figure 1 is a cross-sectional view of the light source unit at the base block. [Figure 4] This is a diagram showing the heating lamp as viewed in the Y direction. [Figure 5] This is a diagram showing the heating lamp as viewed in the Y direction, with the light-receiving heating element removed. [Figure 6A] This graph shows an example of the spectrum of the first ray. [Figure 6B] This graph shows an example of the spectrum of the second light. [Figure 7] This is a schematic cross-sectional view of another embodiment of the light source unit as seen in the X direction. [Figure 8A]This is a schematic cross-sectional view of another embodiment of the heating lamp, viewed in the X direction. [Figure 8B] This is a schematic cross-sectional view of another embodiment of the heating lamp, viewed in the X direction. [Figure 9] This graph plots the relationship between the spectral density of radiation and the wavelength of blackbody radiation at different temperatures. [Modes for carrying out the invention]

[0030] The heating lamp and light source unit of the present invention will be described below with reference to the drawings. Note that the following drawings relating to the heating lamp and light source unit are schematic representations, and the dimensional ratios and numbers shown in the drawings do not necessarily correspond to the actual dimensional ratios and numbers.

[0031] [Light irradiation device 1] Figure 1 is a schematic overall perspective view showing one embodiment of the light irradiation device 1. As shown in Figure 1, the light irradiation device 1 of this embodiment comprises a light source unit 10 and a base 3.

[0032] In the following explanation, as shown in Figure 1, the plane parallel to the illumination surface 2a on which light is shone on the workpiece 2 will be referred to as the XY plane, and the direction perpendicular to the XY plane will be referred to as the Z direction. Furthermore, with respect to the XY plane, the direction in which the workpiece 2 is transported (indicated by the dashed-dotted arrow in Figure 1) will be referred to as the Y direction, and the direction perpendicular to the Y direction will be referred to as the X direction (first direction).

[0033] Similarly, when expressing direction, if positive and negative directions are distinguished, they are written with a positive or negative sign, such as "+Z direction" or "-Z direction." When expressing direction without distinguishing between positive and negative directions, it is simply written as "Z direction."

[0034] As shown in Figure 1, the light irradiation device 1 irradiates the irradiation surface 2a of the workpiece 2, which is being transported in the Y direction, with a heating light, the second light Lx, which will be described later.

[0035] In the following explanation, Work 2 is described as a film-like component with ink applied to the printing area 2b on the irradiation surface 2a, but the object of Work 2 is not limited to this. For example, ink-coated printing paper or board material can also be considered. Furthermore, the object to be dried is not limited to ink, but can also be organic solvents or cleaning solutions, for example.

[0036] The base 3 is a component equipped with a support column 3a for supporting the light source unit 10. Note that the configuration of the light irradiation device 1 shown in Figure 1 is merely an example, and the presence or absence of the base 3, and the configuration of the base 3, are arbitrary.

[0037] [Light source unit 10] Figure 2 is a cross-sectional view AA of the light source unit 10 in Figure 1, and Figure 3 is a cross-sectional view BB of the light source unit 10 in Figure 1. As shown in Figures 2 and 3, the light source unit 10 comprises a cover member 11, a reflector member 12, and a heating lamp 20.

[0038] As shown in Figure 3, the cover member 11 has a reflective member 12 on the inner wall surface side facing the heating lamp 20.

[0039] The reflective member 12 is positioned so that its reflective surface 12a reflects light emitted from the heating lamp 20 and traveling toward the +Z side toward the -Z side. The material constituting the reflective member 12 may be aluminum (Al) or stainless steel (SUS).

[0040] In this embodiment, as shown in Figure 3, the reflective surface 12a of the reflective member 12 is curved, but the shape of the reflective surface 12a can be arbitrarily adjusted depending on how the heating light (second light Lx) is irradiated onto the workpiece 2.

[0041] [Heating lamp 20] Figure 4 is a view of the heating lamp 20 in the Y direction, and Figure 5 is a view of the heating lamp 20 in the Y direction with the light-receiving heating element 21 removed. As shown in Figures 4 and 5, the heating lamp 20 comprises a light-receiving heating element 21 and a halogen lamp 30. The halogen lamp 30 comprises a discharge tube 31, a filament 32, and a pair of power supply units (33, 33). Furthermore, due to the correspondence of each direction as described above, the direction along the tube axis 31a of the discharge tube 31 corresponds to the X direction.

[0042] The light-receiving heat-generating element 21 is a cylindrical member extending in the X direction, which generates heat by absorbing at least a portion of the first light L1 emitted from the halogen lamp 30, and emits a second light Lx having a peak wavelength longer than the peak wavelength of the first light L1.

[0043] The discharge tube 31 is a long, tubular body that is transparent to light belonging to at least the near-infrared region and extends in the X direction, and as shown in Figure 5, it houses a filament 32 that extends inward along the tube axis 31a in the X direction. A halogen gas is sealed in the space in the discharge tube 31 where the filament 32 is housed. The heating lamp 20 emits a first light L1 from the filament 32 when power is supplied to a pair of power supply units (33, 33). The first light L1 is then radiated around the heating lamp 20 via the discharge tube 31.

[0044] As shown in Figure 3, the light-emitting tube 31 is housed inside the light-receiving heat-generating element 21, and is therefore surrounded by the light-receiving heat-generating element 21 in the circumferential direction.

[0045] In this embodiment, as shown in Figure 4, the openings at both ends of the light-receiving heating element 21 are closed by base materials (34, 34) connected to both ends of the discharge tube 31. However, the openings may be left open as long as they surround the discharge tube 31 in the circumferential direction. For example, the entire halogen lamp 30 may be housed inside the light-receiving heating element 21.

[0046] In this embodiment, the light-receiving heating element 21 is a cylindrical member whose main component is SiO2 and which substantially does not transmit the first light L1. The light-receiving heating element 21 can be constructed using a material whose main component is a ceramic other than SiO2, such as Al2O3 or TiO2, which substantially does not transmit the first light L1, but it is preferable to use silica (SiO2), chromium oxide (Cr2O3), iron oxide (Fe2O3), etc.

[0047] Furthermore, the light-receiving heating element 21 may be made of glass or the like, which has been adjusted to substantially prevent the transmission of the first light L1 by incorporating a coloring agent. Note that ceramics and glass are inorganic materials.

[0048] Furthermore, as shown in Figure 3, the heating lamp 20 of this embodiment is configured such that the distance d1 between the light-receiving heating element 21 and the halogen lamp 30 when viewed in the X direction is greater than the diameter Φ1 of the light-emitting tube 31 of the halogen lamp 30.

[0049] More specifically, in this embodiment, the heating lamp 20 has a discharge tube 31 with a diameter Φ1 of 8 mm, an outer diameter of the discharge tube 31 of 10 mm, an inner diameter of the light-receiving heating element 21 of 13 mm, an outer diameter of the light-receiving heating element 21 of 15 mm, and a separation distance d1 of 2.5 mm.

[0050] Furthermore, the temperature of the light-receiving heat-generating element 21 during illumination is determined by the balance between the amount of first light L1 irradiated from the halogen lamp 30 and the amount of heat emitted from the outer wall surface. For this reason, the ratio of the outer diameter of the halogen lamp 30 to the outer diameter of the light-receiving heat-generating element 21 is a parameter related to the peak wavelength of the second light Lx.

[0051] Considering that the power supplied to the halogen lamp 30 does not become unnecessarily large, and the feasibility of adjusting the peak wavelength of the second light Lx to 3 μm or more, the ratio is preferably 1.5 or more, and more preferably 1.8 or more.

[0052] Furthermore, while the light-receiving heating element 21 can be made larger without limit, considering the need to avoid unnecessarily increasing the size of the light irradiation device 1 on which the heating lamp 20 is mounted, the ratio is preferably 8.7 or less, and more preferably 8.5 or less.

[0053] In this embodiment, the shape of the light-receiving heating element 21 is cylindrical, as shown in Figure 3, with a circular cross-section when cut in the YZ plane. However, any shape that can surround the light-emitting tube 31 is acceptable, such as a polygonal tube or an elliptical tube. In such cases, the separation distance d1 is the separation distance between the closest points of the light-receiving heating element 21 and the light-emitting tube 31 when viewed in the X direction.

[0054] Furthermore, if the second light Lx can be emitted at the desired intensity, the distance d1 between the light-receiving heat-generating element 21 and the halogen lamp 30 can be set arbitrarily.

[0055] Figure 6A is a graph showing an example of the spectrum of the first light L1, and Figure 6B is a graph showing an example of the spectrum of the second light Lx. In Figures 6A and 6B, the vertical axis represents the relative intensity with the peak intensity set to 1.0, and the horizontal axis represents the wavelength.

[0056] In this embodiment, the halogen lamp 30 emits a first light L1 with a spectrum having a peak wavelength of 1.2 μm, as shown in Figure 6A, when power is supplied between a pair of electrodes (33, 33).

[0057] In this embodiment, when the light-receiving heat-generating element 21 is irradiated with the first light L1 emitted from the halogen lamp 30, it absorbs at least a portion of the first light L1 and generates heat, emitting a second light Lx with a spectrum having a peak wavelength of 3.0 μm, as shown in Figure 6B.

[0058] Based on the above, the heating lamp 20 with the above configuration, when mounted on the light irradiation device 1 (see Figure 1), can irradiate the workpiece 2 with a second light Lx having a peak wavelength of 2.5 μm or more at a relatively high illuminance without supplying a large amount of power to the halogen lamp 30. Furthermore, the heating lamp 20 with the above configuration does not irradiate the base 3 or support column 3a of the light irradiation device 1 with the first light L1 unnecessarily. In other words, the heating lamp 20 can efficiently heat and dry materials that are expected to be used in the future and that exhibit high absorption characteristics for longer wavelength light compared to conventional materials, while suppressing thermal damage to the workpiece and equipment and reducing energy consumption.

[0059] [Alternative Embodiment] Another embodiment will be described below.

[0060] <1> Figure 7 is a schematic cross-sectional view of another embodiment of the light source unit 10 as seen in the X direction. As shown in Figure 7, the light-receiving heat-generating element 21 may be configured to include a substrate 21a that substantially transmits the first light L1 and a coating layer 21b that emits the second light Lx upon receiving the first light L1.

[0061] The substrate 21a can be made of a material that transmits the first light L1, and for example, a cylindrical tube made of quartz glass can be used.

[0062] The coating layer 21b can be any layer that can absorb the first light L1 and emit the second light Lx, but for example, it is a black coating layer, specifically a chromium-containing coating.

[0063] The heating lamp 20 with the above configuration, when mounted on the light irradiation device 1 (see Figure 1), can irradiate the workpiece 2 with heating light (second light Lx) having a peak wavelength of 2.5 μm or more at a relatively high illuminance without supplying a large amount of power to the halogen lamp 30. Furthermore, the heating lamp 20 with the above configuration does not irradiate the base 3 or support column 3a of the light irradiation device 1 with the first light L1 unnecessarily. In other words, the heating lamp 20 can efficiently heat and dry materials that are expected to be used in the future and that exhibit high absorption characteristics for longer wavelength light compared to conventional materials, while suppressing thermal damage to the workpiece and equipment and reducing energy consumption.

[0064] In this embodiment as well, the preferred sizes and ratios of the inner and outer diameters of the light-emitting tube 31 and the inner and outer diameters of the light-receiving heating element 21 are the same as in the embodiments described above.

[0065] <2> Figures 8A and 8B are schematic cross-sectional views of another embodiment of the heating lamp 20 as seen in the X direction. As shown in Figure 8A, the halogen lamp 30 of the heating lamp 20 may have a first reflective film 35 formed on the wall surface of the discharge tube 31 that reflects the first light L1. The material of the first reflective film 35 may be silica (SiO2), alumina (Al2O3), boron nitride (BN), gold (Au), etc.

[0066] With the above configuration, the first light L1 is directed in a specific direction, and the second light Lx is emitted more efficiently in the part of the light-receiving heat-generating element 21 on the side where the workpiece 2 (see Figure 1) is placed. The first reflective film 35 may be provided on either the inner wall surface or the outer wall surface of the light-emitting tube 31, or it may be provided on both.

[0067] Furthermore, as shown in Figure 8B, the light-receiving heating element 21 of the heating lamp 20 may have a second reflective film 22 formed on its outer surface that reflects the second light Lx. The material of the second reflective film 22 may be silica (SiO2), alumina (Al2O3), boron nitride (BN), gold (Au), etc.

[0068] With the above configuration, the second light Lx can be propagated in a specific direction, and the second light Lx can be radiated more efficiently in the part of the light-receiving heat-generating element 21 on the side where the workpiece 2 (see Figure 1) is placed. Note that, as shown in Figures 8A and 8B, if a reflective film (22, 35) is formed on the heating lamp 20, the light source unit 10 does not need to be equipped with a reflective member 12.

[0069] <3> The configurations of the light irradiation device 1, light source unit 10, and heating lamp 20 described above are merely examples, and the present invention is not limited to the illustrated configurations. [Explanation of Symbols]

[0070] 1 : Light irradiation device 2: Work 2a: Irradiation surface 2b: Print area 3: Pedestal 3a : Post 10: Light source unit 11: Cover component 12: Reflective material 12a : Reflective surface 20: Heating lamp 21 : Main body 21a: Base material 21b: Coating layer 22: Second reflective film 30: Halogen lamp 31: Discharge tube 31a: Tube shaft 32: Filament 33: Power supply unit 34: Base material 35: First reflective film L1: First light Lx: Second light

Claims

1. A halogen lamp comprising a long discharge tube and a filament housed within the discharge tube, wherein the first light emitted by the filament is radiated through the wall surface of the discharge tube, A heating lamp characterized by comprising a light-receiving heating element surrounding the light-emitting tube in the circumferential direction, which generates heat by absorbing the first light and emits a second light whose peak intensity wavelength belongs to a longer wavelength side than the first light.

2. The heating lamp according to claim 1, characterized in that the light-receiving heating element comprises a cylindrical substrate that transmits the first light, and a coating layer formed on the wall surface of the substrate that emits the second light upon receiving the first light.

3. The heating lamp according to claim 1, wherein the light-receiving heating element is made of a material mainly composed of an inorganic material that emits the second light upon receiving the first light, and substantially does not transmit the first light.

4. The heating lamp according to claim 1, characterized in that, when viewed in the direction along the tube axis of the discharge tube, the distance between the discharge tube and the light-receiving heating element of the halogen lamp is greater than the outer diameter of the discharge tube.

5. The heating lamp according to claim 1, characterized in that the halogen lamp is provided with a first reflective film that reflects the first light on the wall surface of the discharge tube in a part of the circumferential direction centered on the tube axis of the discharge tube.

6. The heating lamp according to claim 1, characterized in that the light-receiving heating element has a second reflective film on its outer wall surface in a part of the circumferential direction that reflects the second light.

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