Lamp for heating and light source unit

Abstract

Provided are a lamp for heating and a light source unit with which a solvent, a coating material, or the like adhered to a workpiece can be efficiently dried, and with which uneven drying is inhibited.　The lamp for heating comprises: a main tubular body which extends in a first direction; a main light-emitting body which is accommodated in the main tubular body and which emits first light that has a peak wavelength belonging to the near-infrared region; a first coating layer which reflects a portion of the first light and transmits another portion thereof and which is provided to at least some of a first portion, from among the first portion and a second portion of a tube wall of the main tubular body, the first and second portions facing each other across the tube axis of the main tubular body along a radial direction of the main tubular body; and a second coating layer which is provided to at least some of the second portion and which, upon irradiation with the first light, emits second light that has a peak wavelength belonging to a wavelength range on the longer-wavelength side of the peak wavelength of the first light.

Description

Heating lamps, light source units

[0001] The present invention relates to a heating lamp and a light source unit, and more particularly to a heating lamp and a light source unit that emits light for drying ink applied to a workpiece.

[0002] Conventionally, one method for drying ink applied to the surface of a workpiece such as an object or film material involves irradiating the ink with heating light emitted from a lamp (hereinafter referred to as "heating light"). The method of drying ink by irradiating the workpiece with light is a non-contact method, which has the advantages of eliminating the risk of soiling the workpiece and making it easier to control the temperature reached and the rate of temperature rise compared to methods in which a heat source is placed near the workpiece.

[0003] A known example of a light source for heating is a halogen lamp having a filament housed within a straight tube. Because half of the light emitted from such a halogen lamp is directed away from the workpiece, a reflective film is often formed on the lamp to reflect the light directed away from the workpiece back toward the workpiece. For example, Patent Document 1 listed below discloses a halogen lamp in which a reflective film is formed on the outer surface of the tube in order to improve the efficiency of the power required for lighting the lamp.

[0004] Japanese Patent Application Laid-Open No. 2008-078065

[0005] The present inventors have been studying methods for drying ink applied to the surface of a workpiece by irradiating the surface with heating light, and have noticed the following problems.

[0006] Although there are some variations depending on the type and concentration of the halogen gas sealed in the tube as the light-emitting gas, the intensity peak of the intensity spectrum of the light emitted from the halogen lamp is generally around a wavelength of 1 μm (see FIG. 9).

[0007] However, in many cases, the wavelength band with a relatively high absorption rate in the light absorption spectrum of the ink applied to the workpiece, which is irradiated with light and heated to dry it, differs from the wavelength band with a relatively high light intensity in the halogen lamp emission spectrum.

[0008] Here, through extensive research, the inventors have noticed that the wavelength band of light in which inks used in printing exhibit relatively high absorption rates is often located on the longer wavelength side than the wavelengths in the spectrum of light emitted from a halogen lamp that exhibit relatively high intensity.

[0009] For this reason, when using a halogen lamp as described in Patent Document 1, if ink applied to the surface of a workpiece is dried by irradiating it with heating light emitted from the halogen lamp, it may take a long time for the ink to dry sufficiently, or uneven drying may occur depending on the type of workpiece or the type of ink applied. In particular, uneven drying of the ink may cause the workpiece to shrink in parts, which may cause unintended deformation such as wrinkles or waves, especially in workpieces such as paper or film.

[0010] Furthermore, if there is a large difference between the wavelengths that show a relatively high intensity in the spectrum of light emitted from the halogen lamp and the wavelengths that show a relatively high absorption rate in the absorption spectrum of the ink applied to the workpiece, the ink will not heat up easily and the drying process will take a long time.

[0011] Furthermore, through further research, the inventors have inferred that the situation in which the wavelength band showing high absorptivity and the wavelength band showing high intensity are different may occur not only in inks used in printing, but also in, for example, organic solvents and cleaning solutions for glass substrates.

[0012] In view of the above problems, the present invention aims to provide a heating lamp and a light source unit that can efficiently dry solvents, paints, etc. adhering to a workpiece while suppressing the occurrence of uneven drying.

[0013] The heating lamp of the present invention is characterized by comprising: a main tube extending in a first direction; a main light emitter housed in the main tube and emitting a first light having a peak wavelength within a near-infrared region; a first coating layer provided on at least a part of a first portion of a tube wall of the main tube, the first portion and a second portion of the tube wall facing each other across the tube axis of the main tube in the radial direction of the main tube, the first coating layer reflecting a part of the first light and transmitting the other part; and a second coating layer provided on at least a part of the second portion, emitting a second light having a peak wavelength within a wavelength band longer than that of the first light when irradiated with the first light.

[0014] The first light has different intensities at different locations depending on the shapes of the first and second coating layers, but at least a portion of the first light is emitted toward a specific region. At least a portion of the second light is emitted from the second coating layer toward the specific region irradiated with the first light. In other words, by adjusting the position and orientation of the heating lamp with the above configuration, the first light and the second light can be simultaneously irradiated onto the same region on the surface of the workpiece.

[0015] Therefore, the heating lamp having the above configuration can irradiate the surface of the workpiece with light that is a combination of the first light and the second light, i.e., light whose peak intensity is shifted toward longer wavelengths than the first light emitted from a halogen lamp (see Figure 11).

[0016] More specifically, the heating lamp having the above configuration can irradiate the surface of the workpiece with light whose peak wavelength in the spectrum is closer to the peak wavelength in the absorption spectrum of the solvent than the first light.

[0017] The first coating layer may be formed on a second portion of the wall of the main tubular body, and the second coating layer may be formed on a first portion of the wall of the main tubular body.

[0018] In the heat lamp, the first coating layer may be a white coating layer, and the second coating layer may be a black coating layer.

[0019] The white coating layer exhibits a relatively high reflectance to the first light, and the black coating layer exhibits a relatively high absorbance to the first light.

[0020] In other words, the heating lamp having the above configuration can more efficiently reflect the first light traveling in a direction away from the workpiece toward the workpiece, and can more efficiently generate the second light, which means that the heating lamp having the above configuration can more efficiently dry solvents, paints, etc. adhering to the workpiece.

[0021] In the heat lamp, the first coating layer and the second coating layer may be formed from one end to the other end of the main tube in a direction along the tube axis of the main tube.

[0022] Furthermore, in the heat lamp, the first coating layer may be provided over the entire first portion, and the second coating layer may be provided over the entire second portion.

[0023] In the heat lamp, the second coating layer may have a periodic pattern formed in at least a part of the second portion in a direction along the tube axis of the main tube.

[0024] Heating lamps are generally arranged so that their tube axes are perpendicular to the workpiece transport direction in a plane parallel to the workpiece surface so that light can be uniformly irradiated onto the workpiece surface. Therefore, with the above configuration, the first and second lights emitted from the heating lamp have a relatively uniform illuminance along the tube axis. In other words, the heating lamp with the above configuration can irradiate the entire workpiece with the first and second lights with a more uniform illuminance.

[0025] In reality, the second coating layer does not absorb all of the first light, but transmits a small amount of the first light. Specifically, the transmittance of the second coating layer to the first light can be controlled depending on the thickness of the second coating layer. Therefore, even if the second coating layer is provided on the entire second portion and the second portion is disposed on the workpiece side, the first light and the second light are irradiated onto the surface of the workpiece.

[0026] The heating lamp may further include: a secondary tube extending in the first direction and disposed adjacent to the main tube; a secondary light emitter housed in the secondary tube and emitting a third light having a peak wavelength within the near-infrared region; and a third coating layer provided on at least a part of a third portion of a wall surface of the secondary tube corresponding to the position of the first portion with respect to the tube axis of the main tube, the third coating layer reflecting a part of the third light emitted from the primary light emitter and transmitting another part.

[0027] Furthermore, in the heat lamp, the third coating layer may be a white coating layer.

[0028] The heating lamp may further include: a secondary tube extending in the first direction and disposed adjacent to the main tube; a secondary light emitter housed within the secondary tube and emitting third light having a peak wavelength within the near-infrared region; and a fourth coating layer provided on at least a part of a fourth portion of the wall surface of the secondary tube corresponding to the position of the second portion with respect to the tube axis of the main tube, the fourth coating layer being irradiated with the third light and emitting fourth light having a peak wavelength within a wavelength band longer than that of the third light.

[0029] Furthermore, the heating lamp may further include a third coating layer provided on at least a part of a third part of the wall surface of the secondary tube, which corresponds to the position of the first part relative to the tube axis of the main tube, and which reflects a part of the third light emitted from the primary light emitter and transmits the other part.

[0030] Furthermore, in the heat lamp, the fourth coating layer may be a black coating layer.

[0031] The heating lamp of the above configuration can control the spectrum of light irradiated onto the solvent adhering to the surface of the workpiece by adjusting the intensity spectrum of the first light and second light irradiated onto the surface of the workpiece, as well as the third light or fourth light.

[0032] The light source unit of the present invention is characterized by comprising: a heating lamp according to any one of claims 1 to 8; and a reflecting member disposed on the first portion side of the main tube, which reflects at least a portion of the light emitted from the first portion of the main tube toward the heating lamp.

[0033] The light source unit configured as described above can reflect the first light, which passes through the first coating layer and travels in the direction opposite to the workpiece, back toward the workpiece. This means that the solvent adhering to the surface of the workpiece can be dried more efficiently. Note that this effect also applies to the third light, which passes through the third coating layer.

[0034] According to the present invention, a heating lamp and a light source unit are realized that can efficiently dry solvents, paints, etc. adhering to a workpiece and that can suppress the occurrence of uneven drying.

[0035] 1 is a schematic overall perspective view of an embodiment of a light irradiation device. FIG. 2 is a cross-sectional view taken along line A-A of the light source unit of FIG. 1. FIG. 3 is a cross-sectional view taken along line B-B of the light source unit of FIG. 1. FIG. 4 is a view of a heating lamp viewed from the +Z side. FIG. 5 is a view of a heating lamp viewed from the -Z side. FIG. 6 is a view of a main tube included in the heating lamp viewed in the Y direction. FIG. 7 is a view of a secondary tube included in the heating lamp viewed in the Y direction. FIG. 8 is a view of a main tube from which the first coating layer and the second coating layer have been removed viewed in the Y direction. FIG. 9 is a graph showing an example of the spectrum of the first light and the third light. FIG. 10 is a graph showing an example of the spectrum of the second light and the fourth light. FIG. 11 is a schematic view of another embodiment of a heating lamp viewed from the -Z side. FIG. 12 is a schematic view of another embodiment of a heating lamp viewed from the -Z side. 14A is a schematic diagram of another embodiment of a heating lamp as viewed from the +Z side; FIG. 14B is a schematic diagram of another embodiment of a heating lamp as viewed from the -Z side; FIG. 14C is a schematic diagram of another embodiment of a heating lamp as viewed from the +Y side; FIG. 14D is a schematic diagram of another embodiment of a light source unit as viewed from the -Z side; and FIG. 14B is a cross-sectional view of the light source unit of FIG. 14A as viewed from the -X side.

[0036] The heating lamp and light source unit of the present invention will be described below with reference to the drawings. Note that the drawings relating to the heating lamp and light source unit are all schematic illustrations, and the dimensional ratios and numbers in the drawings do not necessarily correspond to the actual dimensional ratios and numbers.

[0037] [Light Irradiation Device 1] Fig. 1 is an overall perspective view schematically showing one embodiment of a light irradiation device 1. As shown in Fig. 1, the light irradiation device 1 of this embodiment includes a light source unit 10 and a base 3.

[0038] In the following description, as shown in Fig. 1, a plane parallel to the irradiation surface 2a of the workpiece 2 onto which light is irradiated is defined as the XY plane, and a direction perpendicular to the XY plane is defined as the Z direction. Furthermore, with respect to the XY plane, the direction in which the workpiece 2 is transported (the direction indicated by the dashed-dotted arrow in Fig. 1) is defined as the Y direction, and a direction perpendicular to the Y direction is defined as the X direction (first direction).

[0039] Similarly, when expressing a direction, if a distinction is made between positive and negative directions, the direction is written with a positive or negative sign, such as "+Z direction" or "-Z direction," and when a direction is expressed without distinguishing between positive and negative directions, it is simply written as "Z direction."

[0040] As shown in Figure 1, the light irradiation device 1 irradiates heating light (L1, L2) onto an irradiation surface 2a of a workpiece 2 being transported in the Y direction, the irradiation surface 2a including a printing area 2b coated with ink. In the following description, the workpiece 2 is described as a film-like member on which ink is applied to the printing area 2b on the irradiation surface 2a, but the object of the workpiece 2 is not limited to this. For example, printing paper coated with ink or a plate material may also be considered. Furthermore, the object to be dried is not limited to ink, and may also be, for example, an organic solvent or a cleaning liquid.

[0041] The base 3 is a member that includes a support 3a for supporting the light source unit 10. The presence or absence of the base 3 and the configuration of the base 3 are optional.

[0042] [Light Source Unit 10] Fig. 2 is a cross-sectional view taken along line A-A of the light source unit 10 in Fig. 1, and Fig. 3 is a cross-sectional view taken along line B-B of the light source unit 10 in Fig. 1. As shown in Figs. 2 and 3, the light source unit 10 includes a cover member 11, a reflecting member 12, and a heating lamp 20.

[0043] As shown in FIG. 3, the cover member 11 is provided with a reflecting member 12 on the inner wall surface side facing the heating lamp 20 .

[0044] The reflecting member 12 is disposed so that the reflecting surface 12a reflects the light emitted from the heating lamp 20 and traveling toward the +Z side so that the light travels toward the −Z side.

[0045] In this embodiment, as shown in FIG. 3, the reflecting surface 12a of the reflecting member 12 is curved, but the shape of the reflecting surface 12a can be adjusted arbitrarily depending on how the heating light L is irradiated onto the workpiece 2.

[0046] [Heating Lamp 20] Fig. 4 is a drawing of the heating lamp 20 as viewed from the +Z side, and Fig. 5 is a drawing of the heating lamp 20 as viewed from the -Z side. Fig. 6 is a drawing of the main tube 21 of the heating lamp 20 as viewed in the Y direction, and Fig. 7 is a drawing of the secondary tube 31 of the heating lamp 20 as viewed in the Y direction. Fig. 8 is a drawing of the main tube 21 as viewed in the Y direction with the first coating layer 23 and the second coating layer 24 removed.

[0047] In addition, the secondary pipe 31 in this embodiment, from which the third coating layer 33 and the fourth coating layer 34 have been removed, has the same configuration as the main pipe 21 shown in Figure 8, and therefore in Figure 8, the symbol corresponding to the configuration of the secondary pipe 31 is also written in parentheses.

[0048] 4 and 5, the heat lamp 20 includes a main tube 21, a secondary tube 31, and a pair of power supply parts (40, 40) to which power is supplied. The heat lamp 20 of this embodiment is configured so that light is emitted from both the main tube 21 and the secondary tube 31 by supplying power to the pair of power supply parts (40, 40), but the main tube 21 and the secondary tube 31 may each have their own power supply part.

[0049] The main tube 21 is a cylindrical tube that is transmissive to at least light in the near-infrared region and extends in the X direction, and houses a filament 22, which corresponds to the main light emitter and extends along a tube axis 21c in the X direction, as shown in Fig. 8. The space in the main tube 21 that houses the filament 22 is filled with halogen gas.

[0050] Fig. 9 is a graph showing an example of the spectrum of the first light L1 and the third light L3, and Fig. 10 is a graph showing an example of the spectrum of the second light L2 and the fourth light L4. In Fig. 9 and Fig. 10, the vertical axis represents relative intensity when the peak intensity is 1.0, and the horizontal axis represents wavelength. When power is supplied between the pair of electrodes (40, 40), the filament 22 in this embodiment emits the first light L1 having a spectrum with a peak wavelength of 1.2 µm, as shown in Fig. 9.

[0051] A first coating layer 23 is formed on the first portion 21a located on the +Z side of the outer wall surface of the main tube body 21, from one end 21p to the other end 21q, which reflects part of the first light L1 emitted from the filament 22 and transmits the other part.

[0052] The second portion 21b, which is radially opposite the first portion 21a, i.e., located on the -Z side of the outer wall surface of the main tube body 21, is provided with a second coating layer 24 extending from one end 21p to the other end 21q, which is irradiated with the first light L1 and generates heat to emit the second light L2.

[0053] The first coating layer 23 in this embodiment is a white coating layer, and more specifically, is a white sintered film whose main component is silica particles.

[0054] The first coating layer 23 is not particularly limited as long as it is a layer that has the property of reflecting part of the first light L1 and transmitting the other part, but from the viewpoint of heating efficiency, it is preferable that the reflectance for the first light L1 be 30% to 80% and the transmittance be 20% to 70%, and it is even more preferable that the reflectance be 50% to 80% and the transmittance be 20% to 50%.

[0055] The first coating layer 23 does not need to be white as long as it has the property of reflecting part of the first light L1 and transmitting the other part, and in addition to a sintered film whose main component is silica particles, for example, boron nitride, barium nitrate, zirconium oxide, titanium oxide, aluminum oxide, etc. may be used.

[0056] In this embodiment, the second coating layer 24 is a black coating layer, specifically a chromium-containing coating. When the second coating layer 24 is irradiated with the first light L1 and generates heat, it emits second light L2 having a spectrum with a peak wavelength of 2.4 μm, as shown in FIG. 10 .

[0057] In addition, the second coating layer 24 does not need to be black as long as it has the property of emitting light belonging to a wavelength band longer than the peak wavelength of the first light L1 when irradiated with the first light L1 and generating heat, and in addition to a chromium-containing coating, for example, titanium, aluminum oxide, etc. may be used.

[0058] Alternatively, the first coating layer 23 may be formed on the second portion 21b, and the second coating layer 24 may be formed on the first portion 21a.

[0059] The secondary tube 31 is a cylindrical tube that is transparent to at least light in the near-infrared region and extends in the X direction, and houses a filament 32, which corresponds to a secondary light emitter and extends along a tube axis 31c in the X direction, as shown in Fig. 8. The space in which the filament 32 of the secondary tube 31 is housed is filled with halogen gas, similar to the main tube 21.

[0060] A third coating layer 33 is formed on the third portion 31a located on the +Z side of the outer wall surface of the secondary tube body 31, from one end 31p to the other end 31q, which reflects a portion of the third light L3 emitted from the filament 32 and transmits the other portion.

[0061] The fourth portion 31b, which is radially opposite the third portion 31a, i.e., located on the -Z side of the outer wall surface of the secondary tube 31, is provided with a third coating layer 33 and a fourth coating layer 34, which is irradiated with the third light L3, generates heat, and thereby emits the fourth light L4, from one end 31p to the other end 31q, as shown in Figure 7.

[0062] The third coating layer 33 in this embodiment is a white coating layer, and more specifically, is a white sintered film whose main component is silica particles.

[0063] The third coating layer 33 is not particularly limited as long as it is a layer that has the property of reflecting part of the third light L3 and transmitting the other part, but from the viewpoint of heating efficiency, it is preferable that the reflectance for the third light L3 be 30% to 80% and the transmittance be 20% to 70%, and it is preferable that the reflectance be 50% to 80% and the transmittance be 20% to 50%.

[0064] The third coating layer 33 does not need to be white as long as it has the property of reflecting part of the third light L3 and transmitting the other part, and in addition to a sintered film whose main component is silica particles, for example, boron nitride, barium nitrate, zirconium oxide, titanium oxide, aluminum oxide, etc. may be used.

[0065] In this embodiment, the fourth coating layer 34 is a black coating layer, specifically a chromium-containing coating. When the fourth coating layer 34 is irradiated with the third light L3 and generates heat, it emits fourth light L4 having a spectrum with a peak wavelength of 2.4 μm, as shown in FIG. 10 .

[0066] The fourth coating layer 34 does not need to be black as long as it has the property of emitting light belonging to a wavelength band longer than the peak wavelength of the third light L3 when irradiated with the third light L3 and generating heat, and other than a chromium-containing coating, for example, titanium, aluminum oxide, etc. may be used.

[0067] Furthermore, the third coating layer 33 may be formed on the fourth portion 31b, and the fourth coating layer 34 may be formed on the third portion 31a.

[0068] 11 is a graph showing an example of a spectrum of light measured at a position where both the first light L1 and the second light L2 are irradiated, where the vertical axis represents the relative intensity when the peak intensity in the spectrum of light measured at the region irradiated with both the first light L1 and the second light L2 is set to 1.0, and the horizontal axis represents the wavelength.

[0069] Although the spectrum of light measured at a position where both the third light L3 and the fourth light L4 are irradiated is not shown, it is clear that the wavelength at which the intensity peak appears appears between the peak wavelength of the third light L3 and the peak wavelength of the fourth light L4, as in Fig. 11. That is, in this embodiment, the spectrum of light measured in a region where all of the first light L1, the second light L2, the third light L3, and the fourth light L4 are irradiated generally matches the graph shown by the solid line in Fig. 11. However, the spectrum of light measured at a position where the first light L1 and the second light L2 are irradiated may differ from the spectrum of light measured at a position where both the third light L3 and the fourth light L4 are irradiated.

[0070] 1, the irradiation surface 2a of the workpiece 2 is irradiated with heating light L emitted from the light source unit 10. The heating light L is irradiated with heating light (L1, L2, L3, L4), so that light with a spectrum substantially as shown in FIG.

[0071] As described above, the light irradiation device 1, light source unit 10, and heating lamp 20 configured as described above can irradiate the irradiation surface 2a of the workpiece 2 with light whose peak intensity is substantially shifted to the longer wavelength side than the first light L1, as shown in Figure 11, in which the emission spectrum of the first light L1 and the emission spectrum of the second light L2 are superimposed.

[0072] In the above-described embodiment, as shown in FIGS. 5 and 7, the shapes of the coating layers (23, 24) formed on the main pipe 21 and the shapes of the coating layers (33, 34) formed on the secondary pipe 31 are different, but the shapes of the respective coating layers are arbitrary.

[0073] Furthermore, since simultaneous irradiation of the first light L1 and the second light L2 onto the irradiation surface 2a of the workpiece 2 can be achieved using only the main tube body 21, the secondary tube body 31 may be formed with only either the third coating layer 33 or the fourth coating layer 34 for spectrum adjustment.

[0074] Furthermore, from the viewpoint of increasing the extraction efficiency of the first light L1 and the third light L3, and from the viewpoint of being able to visually confirm whether the filaments (22, 32) are emitting light without any problems, the wall surfaces of the main tube body 21 and the secondary tube body 31 may include areas where none of the coating layers (23, 24, 33, 34) are formed.

[0075] Another embodiment will be described below.

[0076] 12A to 12C are schematic diagrams of another embodiment of the heating lamp 20 as viewed from the -Z side. As shown in Fig. 12A, the main tube 21 may have a periodic pattern formed in the direction along the tube axis 21c (X direction) by the second coating layer 24 and light-transmitting portions 25 on which neither of the coating layers (23, 24) is formed.

[0077] Furthermore, as shown in FIG. 12B, the second coating layer 24 and the light-transmitting portions 25 may form a periodic pattern in the circumferential direction of the main pipe 21.

[0078] In addition, the periodic patterns of the second coating layer 24 and the light-transmitting portion 25 formed in the X direction and the circumferential direction of the main tube body 21 can both be the first coating layer 23 and the second coating layer 24.

[0079] As shown in FIG. 12C, the main pipe 21 may have a second coating layer 24 formed on a part of the second portion 21b from one end 21p to the other end 21q.

[0080] 12A to 12C can be similarly adopted in the secondary pipe 31. As shown in FIGS. 12A to 12C, the third coating layer 33, the fourth coating layer 34, and the light-transmitting portion 35 in the secondary pipe 31 may form the same pattern as or a different pattern from the pattern formed by the first coating layer 23, the second coating layer 24, and the light-transmitting portion 25 in the main pipe 21.

[0081] In the main tube 21 and the secondary tube 31, the patterns formed by the coating layers (23, 24, 33, 34) and the light-transmitting portions (25, 35) are appropriately adjusted according to the characteristics required for the heating light L (see Figure 1) to be irradiated onto the irradiation surface 2a of the workpiece 2.

[0082] 13A to 13C are schematic diagrams of another embodiment of the heating lamp 20, where Fig. 13A is a diagram viewed from the +Z side, Fig. 13B is a diagram viewed from the -Z side, and Fig. 13C is a diagram viewed from the +Y side. The heating lamp 20 may be a light source including only a main tube 21, as shown in Figs. 13A to 13C.

[0083] The light irradiation device 1 may be equipped with a plurality of heating lamps 20 each having a main tube 21 and a secondary tube 31. Furthermore, instead of the heating lamp 20 having a main tube 21 and a secondary tube 31 as shown in Fig. 3, a plurality of heating lamps 20 each having only a main tube 21 may be equipped.

[0084] When a plurality of heating lamps 20 each having only a main tube body 21 are mounted on the light irradiation device 1, the shapes of the first coating layer 23 and the second coating layer 24 formed on the wall surface of the main tube body 21 may be the same or different.

[0085] Fig. 14A is a schematic diagram of another embodiment of light source unit 10 as viewed from the -Z side, and Fig. 14B is a cross-sectional view of light source unit 10 of Fig. 14A as viewed from the -Z side. As shown in Fig. 14, light source unit 10 may be equipped with a plurality of heating lamps 20 each including only a main tube 21, and the main tubes 21 of each heating lamp 20 may be arranged in a rotated relationship around the tube axis 21c relative to each other, so that the first light L1 and the second light L2 are irradiated onto at least a partial area on the irradiation surface 2a of workpiece 2.

[0086] 14A and 14B show the light source unit 10 including the heating lamps 20 having the first coating layer 23 and the second coating layer 24 formed in the same manner on the wall surface of the main tube 21, but the coating layers (23, 24) may have different shapes for the heating lamps 20. Furthermore, as shown in Fig. 14B, the light source unit 10 does not have to include the cover member 11 and the reflecting member 12.

[0087] <2> The configurations of the light irradiation device 1, the light source unit 10, and the heating lamp 20 described above are merely examples, and the present invention is not limited to the illustrated configurations.

[0088] 1: Light irradiation device 2: Workpiece 2a: Irradiation surface 2b: Printing area 3: Base 3a: Support 10: Light source unit 11: Cover member 12: Reflection member 12a: Reflection surface 20: Heating lamp 21: Main tube 21a: First portion 21b: Second portion 21c: Tube axis 21p: One end portion 21q: Other end portion 22: Filament 23: First coating layer 24: Second coating layer 25: Light-transmitting portion 31: Sub-tube 31a: Third portion 31b: Fourth portion 31c: Tube axis 31p: One end portion 31q: Other end portion 32: Filament 33: Third coating layer 34 : Fourth coating layer 35 : Transparent part L : Heating light L1 : First light L2 : Second light L3 : Third light L4 : Fourth light

Claims

1. A heating lamp comprising: a main tube extending in a first direction; a main light emitter contained within the main tube and emitting a first light having a peak wavelength within a near-infrared range; a first coating layer provided on at least a part of a first portion and a second portion of a tube wall of the main tube that face each other via the tube axis of the main tube in a radial direction of the main tube, the first coating layer reflecting a part of the first light and transmitting the other portion; and a second coating layer provided on at least a part of the second portion and emitting a second light having a peak wavelength within a wavelength band longer than the peak wavelength of the first light when irradiated with the first light.

2. The heating lamp as claimed in claim 1, wherein the first coating layer is a white coating layer and the second coating layer is a black coating layer.

3. The heat lamp according to claim 1, characterized in that the first coating layer and the second coating layer are formed from one end to the other end of the main tube in a direction along the tube axis of the main tube.

4. The heat lamp according to claim 3, wherein the first coating layer is provided over the entire first portion, and the second coating layer is provided over the entire second portion.

5. The heat lamp according to claim 1, characterized in that the second coating layer has a periodic pattern formed in at least a part of the second portion in a direction along the tube axis of the main tube.

6. The heating lamp according to claim 1, further comprising: a sub-tube extending in the first direction and disposed adjacent to the main tube; a sub-light emitter housed in the sub-tube and emitting a third light having a peak wavelength within a near-infrared region; and a third coating layer provided on at least a part of a third portion of a wall surface of the sub-tube corresponding to the position of the first portion with respect to the tube axis of the main tube, the third coating layer reflecting a part of the third light emitted from the main light emitter and transmitting another part of the third light.

7. The heat lamp according to claim 6, wherein the third coating layer is a white coating layer.

8. The heating lamp according to claim 1, further comprising: a sub-tube extending in the first direction and disposed adjacent to the main tube; a sub-light-emitting element housed within the sub-tube and emitting a third light having a peak wavelength within the near-infrared region; and a fourth coating layer provided on at least a part of a fourth portion of a wall surface of the sub-tube corresponding to the position of the second portion with respect to the tube axis of the main tube, the fourth coating layer being irradiated with the third light and emitting a fourth light having a peak wavelength within a wavelength band longer than the peak wavelength of the third light.

9. The heating lamp according to claim 8, further comprising a third coating layer provided on at least a part of a third portion of the wall surface of the secondary tube, which corresponds to the position of the first portion relative to the tube axis of the main tube, and which reflects a part of the third light emitted from the primary light emitter and transmits the other part.

10. The heat lamp according to claim 8, wherein the fourth coating layer is a black coating layer.

11. A light source unit comprising: a heating lamp as claimed in any one of claims 1 to 10; and a reflecting member disposed on the first portion side of the main tube and reflecting at least a portion of the light emitted from the first portion of the main tube towards the heating lamp.

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