LED lamp

Abstract

A LED lamp 1 that may be used in a low-temperature environment comprises: an LED lamp unit 2 having an LED element; a housing 3 that houses the LED lamp unit 2; and a transparent cover member 4 that transmits light from the LED lamp unit 2, an infrared absorbing member (infrared absorbing layer 6) that absorbs infrared rays from the LED lamp unit 2 and generates heat being provided at a position where heat generated by the infrared absorbing member (infrared absorbing layer 6) is conducted to the transparent cover member 4. According to this LED lamp 1, the transparent cover member 4 can be heated, and problems encountered in low-temperature environments can be overcome.

Description

LED lamp

[0001] The present invention relates to an LED lamp that can be used in low-temperature environments.

[0002] For a long time, halogen bulbs have been the mainstream light source for conventional automotive headlamps (headlights). Halogen bulbs have the property of generating heat when emitting light. Therefore, the transparent cover, which is the outermost component of the headlight, is heated by the heat generated by the halogen bulb. Therefore, even if snow adheres to the transparent cover component when driving in snowfall, the heated transparent cover component melts the snow. As a result, the headlight light is less likely to be blocked by snow adhering to the transparent cover component.

[0003] In response to this, headlights in recent years have been shifting to LED lamps that use LED lamp units as the light source. LED lamps generate significantly less heat when emitting light than halogen bulbs. Therefore, when driving in snow, snow that has adhered to the transparent cover member remains accumulated without melting. As a result, the light from the headlights is blocked by the snow that has accumulated on the transparent cover member.

[0004] Furthermore, forklifts used in freezing and refrigerating facilities may experience condensation on their headlights when they are moved from the low-temperature environment of a freezing or refrigerating warehouse to a room-temperature facility. Furthermore, if the forklift is moved in this state to the low-temperature environment of a freezing or refrigerating warehouse, the water droplets on the headlights will freeze. In this case, the light from the headlights will be blocked by the condensation and freezing. Condensation and freezing on headlights are particularly problematic for autonomous forklifts, as the light from the headlights is necessary for accurate sensor operation.

[0005] Patent document 1 discloses a snow-melting device for rear combination lamps installed at the rear corners of a vehicle, which connects the air inside the vehicle interior to the trunk room and blows the air inside the trunk room onto the outer surface of the rear combination lamp.

[0006] Japanese Unexamined Patent Publication No. 63-74753

[0007] However, a snow melting system for LED lamps used in headlights, etc. was not known.

[0008] The present invention has been made in consideration of the above-described circumstances, and aims to provide an LED lamp that can be used in low-temperature environments and that is capable of heating a transparent cover member.

[0009] In order to achieve the above object, firstly, the present invention provides an LED lamp that can be used in low-temperature environments, comprising an LED lamp unit having an LED element, a housing that accommodates the LED lamp unit, and a transparent cover member that transmits light from the LED lamp unit, wherein an infrared absorbing member that absorbs infrared rays from the LED lamp unit and generates heat is provided in a position where the heat generated by the infrared absorbing member is conducted to the transparent cover member, and / or the transparent cover member itself absorbs infrared rays from the LED lamp unit and generates heat (Invention 1).

[0010] In the above invention (Invention 1), first, when the LED lamp unit emits light, the infrared absorbing member absorbs the infrared rays contained in the light and generates heat. The heat generated by the infrared absorbing member is conducted to the transparent cover member, causing the transparent cover member to heat up. Second, when the LED lamp unit emits light, the transparent cover member absorbs the infrared rays contained in the light and generates heat. As a result, even if snow, ice, or condensation droplets adhere to the transparent cover member, the heated transparent cover member can remove the snow, ice, droplets, etc. As a result, the light from the LED lamp unit is prevented from being blocked by snow, ice, droplets, etc. that adhere to the transparent cover member.

[0011] Secondly, the present invention provides an LED lamp that can be used in low-temperature environments, comprising an LED lamp unit having an LED element, a housing that houses the LED lamp unit, a transparent cover member that transmits light from the LED lamp unit, and a film heater, wherein the film heater is positioned so that heat generated by the film heater is conducted to the transparent cover member (Invention 2).

[0012] In the above invention (Invention 2), when the film heater generates heat, the heat is conducted to the transparent cover member, which is then heated. As a result, even if snow, ice, or condensation droplets adhere to the transparent cover member, the heated transparent cover member can remove the snow, ice, or droplets. As a result, the light from the LED lamp unit is prevented from being blocked by snow, ice, or droplets adhering to the transparent cover member.

[0013] In the above invention (Invention 2), it is preferable that an infrared absorbing member that absorbs infrared rays from the LED lamp unit and generates heat is provided in a position where the heat generated by the infrared absorbing member is conducted to the transparent cover member, and / or that the transparent cover member itself absorbs infrared rays from the LED lamp unit and generates heat (Invention 3).

[0014] In the above inventions (Inventions 1 and 3), it is preferable that the infrared absorbing member is transparent (Invention 4).

[0015] In the above inventions (Inventions 1 to 4), it is preferable that the infrared absorbing member or the transparent cover member contains at least one infrared absorbing material selected from the group consisting of cesium tungsten oxide, lanthanum hexaboride, tin-doped indium oxide, and antimony-doped tin oxide (Invention 5).

[0016] In the above inventions (Inventions 1, 3 to 5), it is preferable that the infrared absorbing member is provided between the LED lamp unit and the transparent cover member (Invention 6).

[0017] In the above inventions (Inventions 1 and 3 to 6), the infrared absorbing member is preferably a layered infrared absorbing layer (Invention 7).

[0018] In the above invention (Invention 7), it is preferable that the infrared absorbing layer is laminated directly or indirectly on the transparent cover member (Invention 8).

[0019] In the above invention (Invention 8), it is preferable that the infrared absorbing layer is laminated on the transparent cover member on the side of the LED lamp unit (Invention 9).

[0020] In the above inventions (Inventions 7 to 9), it is preferable that a weather-resistant layer is laminated directly or indirectly on the infrared absorbing layer (Invention 10).

[0021] In the above inventions (Inventions 7 to 10), it is preferable that an abrasion-resistant layer is laminated directly or indirectly on the infrared absorbing layer (Invention 11).

[0022] In the above inventions (Inventions 7 to 11), it is preferable that a heat insulating layer is laminated directly or indirectly on the infrared absorbing layer (Invention 12).

[0023] In the above inventions (Inventions 7 to 12), the infrared absorbing layer contains an infrared absorbing material, and the content of the infrared absorbing material in the infrared absorbing layer is 0.01 mmol / m per unit area of ​​the infrared absorbing layer. ２ Above, 100 mmol / m ２ It is preferable that the following is true (Invention 13).

[0024] In the above inventions (Inventions 7 to 13), the infrared absorbing layer is formed by applying a material constituting the infrared absorbing layer, and the amount of application of the material constituting the infrared absorbing layer is 0.1 g / m ２ Above, 100g / m ２ It is preferable that the following is true (Invention 14).

[0025] In the above inventions (Inventions 7 to 14), it is preferable that the transmittance of the infrared absorbing layer for light having a wavelength of 850 nm is 0.1% or more and 50% or less (Invention 15).

[0026] In the above inventions (Inventions 7 to 15), it is preferable that the absorbance of the infrared absorbing layer at a wavelength of 850 nm is 0.1 or more and 5 or less (Invention 16).

[0027] In the above inventions (Inventions 2 to 16), it is preferable that the film heater is transparent (Invention 17).

[0028] In the above inventions (Inventions 3 to 17), it is preferable that the infrared absorbing member is a layered infrared absorbing layer, and the infrared absorbing layer and the film heater are laminated directly or indirectly (Invention 18).

[0029] In the above inventions (Inventions 2 to 18), it is preferable that the film heater is laminated directly or indirectly on the transparent cover member (Invention 19).

[0030] In the above invention (Invention 19), it is preferable that the film heater is laminated on the transparent cover member on the side of the LED lamp unit (Invention 20).

[0031] In the above inventions (Inventions 2 to 20), it is preferable that a weather-resistant layer be laminated directly or indirectly on the film heater (Invention 21).

[0032] In the above inventions (Inventions 2 to 21), it is preferable that an abrasion-resistant layer is laminated directly or indirectly on the film heater (Invention 22).

[0033] In the above inventions (Inventions 2 to 22), it is preferable that a heat insulating layer is laminated directly or indirectly on the film heater (Invention 23).

[0034] The LED lamps according to the above inventions (Inventions 1 to 23) may be used for mobile objects (Invention 24), buildings (Invention 25), lighting (Invention 26), signs (Invention 27), signal lights (Invention 28), traffic lights (Invention 29), displays (Invention 30), outdoors (Invention 31), or indoors (Invention 32).

[0035] According to the LED lamp of the present invention, the transparent cover member can be heated.

[0036] 1 is a schematic cross-sectional view of an LED lamp according to a first embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view of an LED lamp according to a second embodiment of the present invention.

[0037] Hereinafter, embodiments of the present invention will be described. [First Embodiment] An LED lamp according to a first embodiment of the present invention is an LED lamp that can be used in low-temperature environments, and includes an LED lamp unit having an LED element, a housing that houses the LED lamp unit, and a transparent cover member that transmits light from the LED lamp unit. The LED lamp according to this embodiment includes an infrared absorbing member that absorbs infrared rays from the LED lamp unit and generates heat, located in a position where the heat generated by the infrared absorbing member is conducted to the transparent cover member (first embodiment), or the transparent cover member itself absorbs infrared rays from the LED lamp unit and generates heat (second embodiment). Note that the LED lamp according to this embodiment may include both the first and second embodiments.

[0038] The light emitted by an LED lamp unit typically contains infrared rays. In the LED lamp (first embodiment) according to this embodiment, when the LED lamp unit emits light, the infrared absorbing member absorbs the infrared rays contained in the light and generates heat. The heat generated by the infrared absorbing member is conducted to the transparent cover member, causing the transparent cover member to heat up. Furthermore, in the LED lamp (second embodiment) according to this embodiment, when the LED lamp unit emits light, the transparent cover member absorbs the infrared rays contained in the light and generates heat. As a result, even if snow, ice, or condensation droplets adhere to the transparent cover member, the heated transparent cover member can remove the snow, ice, droplets, etc. As a result, the light from the LED lamp unit is prevented from being blocked by snow, ice, droplets, etc. adhering to the transparent cover member.

[0039] The LED lamp according to this embodiment (as well as the LED lamp according to a second embodiment described later) can be used in low-temperature environments. Applications where snow or ice may accumulate or condensation may occur are not particularly limited, and the LED lamp may be used indoors or outdoors. For example, the LED lamp may be used for mobile objects such as vehicles, ships, aircraft, and drones, or for buildings, lighting, traffic lights, signposts, signs, and displays installed outdoors or in refrigeration / freezing facilities. Examples of vehicles include, but are not limited to, automobiles, forklifts, motorcycles, bicycles, and trains. In particular, forklifts used in refrigeration / freezing facilities may develop condensation on their headlights when moved from the low-temperature environment of a refrigerated warehouse to a room-temperature facility. Furthermore, if the forklift is moved in this state to the low-temperature environment of a refrigerated warehouse, the water droplets on the headlights may freeze. However, the use of the LED lamp according to this embodiment prevents the headlight light from being blocked by condensation or freezing. This allows for accurate operation of sensors using headlight light, particularly in self-driving forklifts.

[0040] Hereinafter, as a preferred embodiment, an LED lamp as an automobile headlamp (headlight) will be described with reference to the drawings.

[0041] As shown in Figure 1, the LED lamp 1 (first form) of this embodiment includes an LED lamp unit 2, a housing 3 that accommodates the LED lamp unit 2, and a transparent cover member 4 that transmits light from the LED lamp unit 2.

[0042] The LED lamp unit 2 includes an LED element 21, a reflector 22 that reflects light from the LED element 21, and a lens 23 that adjusts the direction of the light from the reflector 22. The LED lamp unit 2 is fixed to the housing 3 via a lamp unit support member 31.

[0043] The housing 3 has an opening on the front side (the side that emits light as a headlight), and a transparent cover member 4 is installed to cover the opening. The transparent cover member 4 is fixed to the housing 3, for example, by fitting into a slit provided in the housing 3.

[0044] In the LED lamp 1 according to this embodiment, a weather-resistant layer 5, an infrared absorbing layer 6, and a scratch-resistant layer 7 are laminated in this order on the inner surface of the transparent cover member 4. In this configuration, heat generated by the infrared absorbing layer 6 is conducted to the transparent cover member 4.

[0045] The weather-resistant layer 5, the infrared absorbing layer 6, and the scratch-resistant layer 7 may be provided on the entire inner surface of the transparent cover member 4, or on a part of the inner surface. In this embodiment, the weather-resistant layer 5 and / or the scratch-resistant layer 7 are not necessarily required and may be omitted.

[0046] The weather-resistant layer 5 is a layer that mainly improves the weather resistance of the infrared absorbing layer 6 and suppresses deterioration in low-temperature environments, and is preferably a coating layer formed by coating a material containing an additive that imparts weather resistance and a binder. Examples of additives that can impart weather resistance include ultraviolet absorbers, light stabilizers, antioxidants, and oxygen absorbers. More specifically, the coating layer is preferably formed by coating a material that contains at least one of an ultraviolet absorber, a light stabilizer, an antioxidant, and an oxygen absorber, and a binder, and it is particularly preferable that the coating layer be a transparent coating layer.

[0047] From the viewpoint of the SDGs, a material with a high biomass content, a material that can be recycled or reused, or a recycled or reused material may be used as the material constituting the weather-resistant layer 5. Furthermore, it is also preferable that the weather-resistant layer 5 contains an additive such as an additive that prevents yellowing, and is also preferably made of a material that prevents the occurrence of blisters.

[0048] Examples of binders that can be used in the weather-resistant layer 5 include synthetic resin binders such as polyester resin, modified nylon resin, chlorinated ethylene vinyl alcohol, chlorinated polypropylene, chlorinated polyethylene, ethylene vinyl alcohol, vinyl acetate, acrylic resin, urethane acrylate resin, cellulose resin, epoxy resin, phenolic resin, polyurethane resin, butyral resin, diallyl phthalate resin, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, silicone resin, etc. One type of binder may be used alone, or two or more types may be used in combination.

[0049] Examples of ultraviolet absorbers that can be used in the weather-resistant layer 5 include benzophenone-based compounds, benzotriazole-based compounds, triazine-based compounds, cyanoacrylate-based compounds, and salicylic acid ester-based compounds. One type of ultraviolet absorber may be used alone, or two or more types may be used in combination. The amount of ultraviolet absorber used is preferably 0.001 to 30% by mass, and particularly preferably 0.01 to 15% by mass, of the materials constituting the weather-resistant layer 5.

[0050] Examples of light stabilizers that can be used in the weather-resistant layer 5 include hindered amine light stabilizers, benzophenone light stabilizers, and benzotriazole light stabilizers. These light stabilizers may be used alone or in combination of two or more. The amount of the light stabilizer used is preferably 0.001 to 10% by mass, and particularly preferably 0.01 to 1% by mass, of the materials that constitute the weather-resistant layer 5.

[0051] Examples of antioxidants that can be used in the weather-resistant layer 5 include phosphorus-based antioxidants, phenol-based antioxidants (a preferred example is dibutylhydroxytoluene (BHT)), and sulfur-based antioxidants. One type of antioxidant may be used alone, or two or more types may be used in combination. The amount of antioxidant used is preferably 0.001 to 10% by mass, and particularly preferably 0.01 to 1% by mass, of the material that constitutes the weather-resistant layer 5.

[0052] Examples of oxygen absorbers that can be used in the weather-resistant layer 5 include inorganic oxygen absorbers such as reducing metal compounds, and organic oxygen absorbers. One type of oxygen absorber may be used alone, or two or more types may be used in combination. The amount of oxygen absorber used is preferably 0.001 to 10% by mass, and particularly preferably 0.01 to 1% by mass, of the materials that constitute the weather-resistant layer 5.

[0053] The thickness of the weather-resistant layer 5 is not particularly limited, but is usually preferably 1 to 10,000 μm, more preferably 5 to 5,000 μm, particularly preferably 10 to 1,000 μm, and even more preferably 10 to 500 μm.

[0054] The weather-resistant layer 5 may be laminated to the transparent cover member 4 via a desired adhesive layer (pressure-sensitive adhesive layer), or may be laminated directly to the transparent cover member 4. When the weather-resistant layer 5 is laminated directly to the transparent cover member 4, the material that constitutes the weather-resistant layer 5 can be applied to the transparent cover member 4 to form the weather-resistant layer 5.

[0055] The infrared absorbing layer 6 absorbs infrared rays contained in the light emitted by the LED lamp unit 2 and generates heat. The infrared absorbing layer 6 may be made of any material that can perform this function. In this embodiment, the infrared absorbing layer 6 must be transparent, but it does not have to be transparent depending on the location where it is provided.

[0056] The infrared absorbing layer 6 may be, for example, a coating layer formed by coating a material containing an infrared absorbing material and a binder, a film into which the infrared absorbing material is kneaded, or an adhesive layer containing the infrared absorbing material and an adhesive (including the concept of a pressure-sensitive adhesive).

[0057] From the viewpoint of the SDGs, a material with a high biomass content, a material that can be recycled or reused, or a recycled or reused material may be used as the material constituting the infrared absorbing layer 6. Furthermore, the infrared absorbing layer 6 preferably contains an additive such as an additive that prevents yellowing or an additive that imparts weather resistance, and is also preferably made of a material that prevents the occurrence of blisters.

[0058] Examples of the infrared absorbing material include inorganic infrared absorbers such as tin oxide, indium oxide, magnesium oxide, titanium oxide, chromium oxide, zirconium oxide, nickel oxide, aluminum oxide, zinc oxide, iron oxide, antimony oxide, lead oxide, bismuth oxide, cesium tungsten oxide, lanthanum hexaboride, tin-doped indium oxide, and antimony-doped tin oxide, and organic infrared absorbers such as phthalocyanines, naphthalocyanines, and anthraquinones. One type of infrared absorbing material may be used alone, or two or more types may be used in combination.

[0059] The infrared absorbing layer 6 preferably contains, as an infrared absorbing material, at least one selected from the group consisting of cesium tungsten oxide, lanthanum hexaboride, tin-doped indium oxide, and antimony-doped tin oxide. Commercially available cesium tungsten oxide products include "CWO" (registered trademark) and "YMF-02AS" manufactured by Sumitomo Metal Mining Co., Ltd. Commercially available lanthanum hexaboride products include "KHF-7AH" manufactured by Sumitomo Metal Mining Co., Ltd. These infrared absorbing materials are characterized by high infrared absorption efficiency and easy heat generation while maintaining high transmittance for visible light.

[0060] The content of the infrared absorbing material in the infrared absorbing layer 6 is 0.01 to 100 g / m per unit area of ​​the infrared absorbing layer 6. ２ It is preferable that the density is 0.05 to 50 g / m ２ It is more preferable that the density is 0.1 to 10 g / m ２ This makes it easier for the infrared absorbing layer 6 to satisfy the optical properties described below and also makes it easier to obtain the desired heat generation performance.

[0061] The content of the infrared absorbing material in the infrared absorbing layer 6 is 0.01 to 100 mmol / m per unit area of ​​the infrared absorbing layer 6. ２ is preferably 0.05 to 50 mmol / m ２ It is more preferable that the concentration is 0.5 to 20 mmol / m ２ It is preferable that the concentration is 1 to 10 mmol / m ２ This makes it easier for the infrared absorbing layer 6 to satisfy the optical properties described below and also makes it easier to obtain the desired heat generation performance.

[0062] Examples of binders that can be used in the infrared absorbing layer 6 include the same materials as the binders that can be used in the weather-resistant layer 5. The binders may be used alone or in combination of two or more.

[0063] Films that can be used for the infrared absorbing layer 6 are films into which an infrared absorbing material has been kneaded, and examples thereof include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyolefin films such as polyethylene and polypropylene, cellulose films such as triacetyl cellulose, polyurethane films, polyvinyl chloride films, polyvinylidene chloride films, polyvinyl alcohol films, ethylene-vinyl acetate copolymer films, polystyrene films, polycarbonate films, acrylic resin films, norbornene resin films, and cycloolefin resin films; and plastic films such as laminates of two or more of these. The plastic film may be uniaxially or biaxially stretched.

[0064] The film preferably contains additives such as additives that prevent yellowing and additives that impart weather resistance, and is also preferably made of a material that prevents the occurrence of blisters.

[0065] Examples of adhesives that can be used for the infrared absorbing layer 6 include acrylic adhesives, polyurethane adhesives, epoxy adhesives, polyester adhesives, and polyester-polyurethane adhesives. Examples of pressure-sensitive adhesives (adhesives) that can be used for the infrared absorbing layer 6 include acrylic adhesives, polyester adhesives, polyurethane adhesives, rubber adhesives, and silicone adhesives.

[0066] The thickness of the infrared absorbing layer 6 is preferably 0.01 to 10,000 μm, more preferably 0.1 to 1,000 μm, and even more preferably 1 to 100 μm.

[0067] When the infrared absorbing layer 6 is a coating layer, the material constituting the infrared absorbing layer 6 may be applied to the weather-resistant layer 5 (or the transparent cover member 4 if the weather-resistant layer 5 is omitted) to form the infrared absorbing layer 6. In this case, the material constituting the infrared absorbing layer 6 preferably comprises a material containing a binder and an infrared absorbing material, and the content of the infrared absorbing material is preferably 10 to 10,000 parts by mass, more preferably 50 to 5,000 parts by mass, particularly preferably 100 to 1,000 parts by mass, and even more preferably 250 to 600 parts by mass, per 100 parts by mass of the binder. This makes it easier to achieve desirable optical properties while exhibiting the desired heat generation performance. Furthermore, the amount of the material constituting the infrared absorbing layer 6 to be applied is preferably 0.1 to 100 g / m. ２ It is preferable that the density is 0.4 to 70 g / m ２ More preferably, it is 0.8 to 40 g / m ２ It is preferable that the density is 1.2 to 20 g / m ２ It is preferable that:

[0068] When the infrared absorbing layer 6 is a film, it can be laminated to the weather-resistant layer 5 (or the transparent cover member 4 when the weather-resistant layer 5 is omitted) via a desired adhesive layer (pressure-sensitive adhesive layer). When the infrared absorbing layer 6 is an adhesive layer, the weather-resistant layer 5 (or the transparent cover member 4 when the weather-resistant layer 5 is omitted) and the scratch-resistant layer 7 (for example, a film having a hard coat layer) can be bonded via the infrared absorbing layer 6.

[0069] The total light transmittance of the infrared absorbing layer 6 is preferably 1 to 99%, more preferably 10 to 95%, particularly preferably 25 to 90%, even more preferably 40 to 85%, and most preferably 50 to 85%. This makes it easier to obtain the desired infrared absorption and, ultimately, the desired heat generation performance while ensuring the brightness of the LED lamp. The total light transmittance in this specification is a value measured in accordance with JIS K7361-1:1997, and the specific test method is as shown in the test examples described below.

[0070] The haze value of the infrared absorbing layer 6 is preferably 10% or less, more preferably 6% or less, particularly preferably 3% or less, even more preferably 2% or less, and most preferably 1.5% or less. This ensures the brightness of the LED lamp. The lower limit of the haze value may be 0%, but in practice it is preferably 0.01% or more, particularly preferably 0.1% or more. The haze value in this specification is a value measured in accordance with JIS K7136:2000, and the specific test method is as shown in the test examples described below.

[0071] The lightness L* of the infrared absorbing layer 6, as defined by the CIE 1976 L*a*b* color system, is preferably 10 or more, more preferably 35 or more, particularly preferably 60 or more, even more preferably 70 or more, and most preferably 80 or more. This ensures the brightness of the LED lamp. The upper limit of the lightness L* may be 100, but in practice it is preferably 98 or less, particularly preferably 96 or less, and even more preferably 94 or less. The method for measuring lightness L* in this specification is as shown in the test examples described below.

[0072] The light transmittance of the infrared absorbing layer 6 at a wavelength of 850 nm is preferably 50% or less, more preferably 35% or less, particularly preferably 20% or less, even more preferably 10% or less, and especially preferably 5% or less. This makes it easier to obtain excellent infrared absorption and, ultimately, excellent heat generation performance. From the viewpoint of ensuring the brightness of the LED lamp, the lower limit of the light transmittance at a wavelength of 850 nm is preferably 0.1% or more, more preferably 0.5% or more, especially preferably 1% or more, even more preferably 2% or more, and especially preferably 2.5% or more. The method for measuring light transmittance in this specification is as shown in the test examples described below.

[0073] The absorbance of the infrared absorbing layer 6 at a wavelength of 850 nm is preferably 0.1 or more, more preferably 0.4 or more, particularly preferably 0.7 or more, even more preferably 1 or more, and especially preferably 1.4 or more. This makes it easier to obtain excellent infrared absorption and, ultimately, excellent heat generation performance. From the viewpoint of ensuring the brightness of the LED lamp, the upper limit of the absorbance at a wavelength of 850 nm is preferably 5 or less, more preferably 4 or less, especially preferably 3 or less, even more preferably 2 or less, and especially preferably 1.8 or less. The method for measuring absorbance in this specification is as shown in the test examples described below.

[0074] The scratch-resistant layer 7 is a layer for imparting scratch resistance to the infrared absorbing layer 6. The scratch-resistant layer 7 can be formed, for example, of a hard coat layer, a film having a hard coat layer, or a film having scratch resistance. In this embodiment, the scratch-resistant layer 7 needs to be transparent.

[0075] From the viewpoint of the SDGs, a material with a high biomass content, a recyclable or reusable material, or a recycled or reused material may be used as the material constituting the scratch-resistant layer 7. The scratch-resistant layer 7 also preferably contains additives such as an additive that prevents yellowing and an additive that imparts weather resistance, and is also preferably made of a material that prevents the occurrence of blisters.

[0076] The hard coat layer is usually made of a curable material, and may be thermosetting or active energy ray-curable. If it is thermosetting, it is made of a cured coating composition containing a thermosetting compound as an essential component and, optionally, a leveling agent, a filler, etc. If it is active energy ray-curable, it is made of a cured coating composition containing an active energy ray-curable compound as an essential component and, optionally, a leveling agent, a filler, a photopolymerization initiator, etc. As the active energy ray-curable compound, a multifunctional (meth)acrylate is preferably used. In this specification, the term "(meth)acrylate" refers to both acrylate and methacrylate. The same applies to other similar terms.

[0077] The film may be the same as the film in the case where the infrared absorbing layer 6 is a film having an infrared absorbing material kneaded therein. Examples of the scratch-resistant film include a hard coat film.

[0078] When the scratch-resistant layer 7 is a hard coat layer, the thickness of the scratch-resistant layer 7 is preferably 0.1 to 100 μm, more preferably 0.5 to 60 μm, particularly preferably 1 to 30 μm, further preferably 1.5 to 20 μm, and of these, preferably 2 to 10 μm. When the scratch-resistant layer 7 is a film having a hard coat layer or a film having scratch resistance, the thickness of the scratch-resistant layer 7 is preferably 0.1 to 100 μm, more preferably 0.5 to 60 μm, particularly preferably 1 to 30 μm, further preferably 1.5 to 20 μm, and of these, preferably 2 to 10 μm.

[0079] The pencil hardness of the abrasion-resistant layer 7 (scratch hardness measured by the pencil method in accordance with JIS K5600-5-4:1999) is preferably B or higher, more preferably HB or higher, particularly preferably F or higher, and even more preferably H or higher. The pencil hardness is preferably 10H or lower, more preferably 8H or lower, particularly preferably 6H or lower, and even more preferably 4H or lower.

[0080] When the scratch-resistant layer 7 is a hard coat layer, the material constituting the hard coat layer may be applied to the infrared absorbing layer 6 (when the infrared absorbing layer 6 is not an adhesive layer) to form the scratch-resistant layer 7. When the scratch-resistant layer 7 is a film having a hard coat layer or a film having scratch resistance, and the infrared absorbing layer 6 is not an adhesive layer, the scratch-resistant layer 7 may be laminated to the infrared absorbing layer 6 via a desired adhesive layer (pressure-sensitive adhesive layer). When the scratch-resistant layer 7 is a film having a hard coat layer or a film having scratch resistance, and the infrared absorbing layer 6 is an adhesive layer, the scratch-resistant layer 7 may be laminated to the weather-resistant layer 5 (or the transparent cover member 4 when the weather-resistant layer 5 is omitted) via the infrared absorbing layer 6.

[0081] Although not shown, in this embodiment, a transparent heat insulating layer may be laminated on the inner surface of the scratch-resistant layer 7. The transparent heat insulating layer is a layer that, due to its heat insulating properties, prevents a decrease in the temperature of the heated infrared absorbing layer 6 (infrared absorbing member).

[0082] The transparent heat insulating layer is not particularly limited as long as it transmits light from the LED lamp unit 2 without any problems. For example, it may be a transparent porous layer, a film having a transparent porous layer, or a layer containing hollow particles or porous particles. Examples of transparent porous layers include polymer layers having a porous structure. Examples of porous structures include those derived from the microphase separation structure of block copolymers. Examples of layers containing hollow particles include resin layers containing hollow silica-shelled microparticles.

[0083] The thickness of the transparent heat insulating layer is not particularly limited, but is usually preferably 1 to 1000 μm, particularly preferably 5 to 500 μm, and further preferably 10 to 100 μm.

[0084] The transparent heat insulating layer may be laminated on the scratch-resistant layer 7 (or on the infrared absorbing layer 6 when the scratch-resistant layer 7 is omitted) via a desired adhesive layer (pressure-sensitive adhesive layer), for example.

[0085] Here, the housing 3 may be made of a material having heat insulation properties or may include a member having heat insulation properties, thereby improving the heat retention of the air surrounded by the housing 3 and the transparent cover member 4 and suppressing a decrease in the temperature of the heated infrared absorption layer 6.

[0086] In the LED lamp 1 according to this embodiment, when power is supplied to the LED lamp unit 2 from an external source, the LED elements 21 emit light. The light is reflected by the reflector 22 and emitted forward through the lens 23. When the LED lamp unit 2 emits light in this manner, the infrared absorbing layer 6 absorbs the infrared rays contained in the light and generates heat. The heat generated by the infrared absorbing layer 6 is conducted to the transparent cover member 4 via the weather-resistant layer 5, heating the transparent cover member 4. As a result, even if snow, ice, or condensation droplets adhere to the transparent cover member 4, the snow, ice, droplets, etc. can be removed by the heated transparent cover member 4. As a result, the light from the LED lamp unit 2 is prevented from being blocked by snow, ice, droplets, etc. adhering to the transparent cover member 4.

[0087] In this embodiment, the laminate having the weather-resistant layer 5, the infrared absorbing layer 6, and the scratch-resistant layer 7 can be attached to the transparent cover member 4, for example, by a fastening member, without using an adhesive or the like.

[0088] In another embodiment, the infrared absorbing layer 6 may be laminated on the outside of the transparent cover member 4. In this case, for example, the layers may be laminated in the following order: transparent cover member 4 / infrared absorbing layer 6 / weather-resistant layer 5 / scratch-resistant layer 7, and a transparent heat insulating layer may be interposed between the infrared absorbing layer 6 and the weather-resistant layer 5, or between the weather-resistant layer 5 and the scratch-resistant layer 7. Even in such an embodiment, the weather-resistant layer 5 and / or the scratch-resistant layer 7 (and the transparent heat insulating layer) may be omitted.

[0089] In yet another embodiment, the infrared absorbing layer 6 may be provided apart from the transparent cover member 4 without being laminated on the transparent cover member 4. For example, a member supporting the infrared absorbing layer 6 (and other layers) may be disposed between the transparent cover member 4 and the lens 23 of the LED lamp unit 2. Even in this case, the heat generated by the infrared absorbing layer 6 (infrared absorbing member) can be conducted to the transparent cover member 4 via the air surrounded by the housing 3 and the transparent cover member 4.

[0090] In yet another embodiment, the infrared absorbing layer 6 may be disposed in a location other than between the transparent cover member 4 and the lens 23 of the LED lamp unit 2, where the infrared absorbing layer 6 is exposed to light (infrared rays) from the LED lamp unit 2. Even in this case, the heat generated by the infrared absorbing layer 6 (infrared absorbing member) can be conducted to the transparent cover member 4 via the air surrounded by the housing 3 and the transparent cover member 4. In this embodiment, the infrared absorbing layer 6 does not have to be transparent.

[0091] In yet another embodiment, the infrared absorbing layer 6 may be provided inside the LED lamp unit 2 .

[0092] In the LED lamp of the second embodiment, the infrared absorbing layer 6 is omitted from the LED lamp 1 according to the above embodiment. On the other hand, the transparent cover member 4 has the function of absorbing infrared rays from the LED lamp unit 2 and generating heat.

[0093] In this configuration, when the LED lamp unit 2 emits light, the transparent cover member 4 absorbs the infrared rays contained in the light and generates heat. As a result, even if snow, ice, or condensation droplets adhere to the transparent cover member 4, the snow, ice, droplets, etc. can be removed by the heated transparent cover member 4. As a result, the light from the LED lamp unit 2 is prevented from being blocked by snow, ice, droplets, etc. that adhere to the transparent cover member.

[0094] The transparent cover member 4 is usually made of transparent plastic or glass, and in this embodiment, an infrared absorbing material is kneaded into these materials. The type and content of the infrared absorbing material are the same as those in the above-mentioned embodiment.

[0095] The transparent cover member 4 also preferably contains additives such as additives that prevent yellowing and additives that impart weather resistance.

[0096] [Second embodiment] An LED lamp according to a second embodiment of the present invention is an LED lamp that can be used in low-temperature environments, and includes an LED lamp unit having an LED element, a housing that houses the LED lamp unit, and a transparent cover member that transmits light from the LED lamp unit, and further includes a film heater that is positioned so that heat generated by the film heater is conducted to the transparent cover member.

[0097] In the LED lamp according to this embodiment, when the film heater generates heat, the heat is conducted to the transparent cover member, which is then heated. As a result, even if snow, ice, or condensation droplets adhere to the transparent cover member, the heated transparent cover member can remove the snow, ice, or droplets. As a result, the light from the LED lamp unit is prevented from being blocked by snow, ice, or droplets adhering to the transparent cover member.

[0098] The LED lamp according to this embodiment preferably further comprises an infrared absorbing member that absorbs infrared rays from the LED lamp unit and generates heat, in a position where the heat generated by the infrared absorbing member is conducted to the transparent cover member (first embodiment), or the transparent cover member itself absorbs infrared rays from the LED lamp unit and generates heat (second embodiment). Note that the LED lamp according to this embodiment may comprise both the first and second embodiments.

[0099] Light emitted by an LED lamp unit typically contains infrared rays. In the LED lamp (first embodiment) according to this embodiment, when the LED lamp unit emits light, the infrared absorbing member absorbs the infrared rays contained in the light and generates heat. The heat generated by the infrared absorbing member is conducted to the transparent cover member, so that the transparent cover member is heated by the infrared absorbing member together with the film heater. Furthermore, in the LED lamp (second embodiment) according to this embodiment, when the LED lamp unit emits light, the transparent cover member absorbs the infrared rays contained in the light and generates heat. As a result, even if snow, ice, or condensation droplets adhere to the transparent cover member when the film heater generates a relatively small amount of heat, the snow, ice, droplets, etc. can be removed by the heated transparent cover member.

[0100] Hereinafter, as a preferred embodiment, an LED lamp as an automobile headlamp (headlight) will be described with reference to the drawings.

[0101] As shown in Figure 2, the LED lamp 1A (first form) of this embodiment includes an LED lamp unit 2, a housing 3 that accommodates the LED lamp unit 2, and a transparent cover member 4 that transmits light from the LED lamp unit 2.

[0102] The LED lamp unit 2 includes an LED element 21, a reflecting mirror 22 that reflects light from the LED element 21, and a lens 23 that adjusts the direction of the light from the reflecting mirror 22. The LED lamp unit 2 is fixed to the housing 3 via a lamp unit support member 31.

[0103] The housing 3 has an opening on the front side (the side that emits light as a headlight), and a transparent cover member 4 is installed to cover the opening. The transparent cover member 4 is fixed to the housing 3, for example, by fitting into a slit provided in the housing 3.

[0104] In the LED lamp 1A according to this embodiment, a weather-resistant layer 5, a film heater 8, an infrared absorbing layer 6, and a scratch-resistant layer 7 are laminated in this order on the inner surface of the transparent cover member 4. In this configuration, the heat generated by the film heater 8 and the infrared absorbing layer 6 is conducted to the transparent cover member 4.

[0105] The weather-resistant layer 5, film heater 8, infrared absorbing layer 6, and scratch-resistant layer 7 may be provided on the entire inner surface of the transparent cover member 4, or on a portion of the inner surface. In this embodiment, the layers other than the film heater 8 are not necessarily required and may be omitted.

[0106] The weather-resistant layer 5, film heater 8, infrared absorbing layer 6, and scratch-resistant layer 7 may each be provided on the outer surface of the transparent cover member 4, but it is preferable that at least the film heater 8 be provided on the inner surface of the transparent cover member 4. This improves the durability and weather resistance of the transparent cover member 4, including the electric cable for supplying power to the film heater 8.

[0107] At least the film heater 8 is preferably provided on 10% or more (area ratio) of the inner surface of the transparent cover member 4, more preferably 25% or more, particularly preferably 50% or more, and even more preferably 75% or more. The upper limit is 100%. This allows most of the transparent cover member 4 to be heated, thereby removing ice, snow, and water droplets from most of the transparent cover member 4 and allowing light from the LED lamp unit 2 to be emitted without any problems.

[0108] The film heater 8 is a planar heating element that generates heat when power is supplied. Although not shown, an electric cable for power supply is electrically connected to the film heater 8. In this embodiment, the film heater 8 needs to be transparent (transparent enough to transmit light from the LED lamp unit 2), but it does not have to be transparent depending on the location where it is installed.

[0109] A conventionally known film heater can be used as the film heater 8. The film heater 8 is mainly classified into an electric heating wire type and a surface heating type, and either type may be used.

[0110] The electric heating wire type is usually a film substrate on which heater wires (conductive linear bodies) made of metal foil such as aluminum foil, copper foil, or stainless steel foil, conductor wires such as copper wire or nichrome wire, or conductive paste, etc., are arranged. The film heater 8 can be made transparent by using an extremely thin heater wire or by reducing the density of the heater wire.

[0111] The surface heating type typically has a conductive film formed on a film substrate as a heater layer, with electrodes placed on both ends of the heater layer, generating heat across the entire surface between the electrodes. Examples of heater layers include those coated with conductive ink, metal films formed by vapor deposition or sputtering, and those with a mesh of metal foil heater wires that mimics surface heating. The film heater 8 can be made transparent by using a transparent conductive film, a thin metal film, an extremely fine mesh of heater wires, or a coarse mesh.

[0112] Among the above, a preferred film heater 8 is a surface heating type that uses a transparent conductive film. Examples of transparent conductive films include those made of metals such as platinum, gold, silver, and copper; oxides such as tin oxide, indium oxide, cadmium oxide, zinc oxide, and zinc dioxide; composite oxides such as tin-doped indium oxide (ITO), zinc oxide-doped indium oxide, fluorine-doped indium oxide, antimony-doped tin oxide, fluorine-doped tin oxide, and aluminum-doped zinc oxide; and non-oxide compounds such as chalcogenides, lanthanum hexaboride, titanium nitride, and titanium carbide. Of these, those made of tin-doped indium oxide (ITO) are preferred.

[0113] The thickness of the film heater 8 is not particularly limited, but is usually preferably 1 to 5000 μm, more preferably 5 to 3000 μm, particularly preferably 10 to 1000 μm, and even more preferably 15 to 500 μm.

[0114] The film heater 8 can be laminated to the weather-resistant layer 5 (or the transparent cover member 4 when the weather-resistant layer 5 is omitted) via a desired adhesive layer (pressure-sensitive adhesive layer), for example.

[0115] When the infrared absorbing layer 6 is a coating layer, the material constituting the infrared absorbing layer 6 may be applied to the film heater 8 to form the infrared absorbing layer 6. When the infrared absorbing layer 6 is a film, it may be laminated to the film heater 8 via a desired adhesive layer (pressure-sensitive adhesive layer). When the infrared absorbing layer 6 is an adhesive layer, the film heater 8 and the scratch-resistant layer 7 (for example, a film having a hard coating layer) may be bonded via the infrared absorbing layer 6.

[0116] When the scratch-resistant layer 7 is a hard coat layer, a material constituting the hard coat layer may be applied to the infrared absorbing layer 6 (when the infrared absorbing layer 6 is not an adhesive layer) to form the scratch-resistant layer 7. When the scratch-resistant layer 7 is a film having a hard coat layer or a film having scratch resistance and the infrared absorbing layer 6 is not an adhesive layer, the scratch-resistant layer 7 may be laminated to the infrared absorbing layer 6 via a desired adhesive layer (pressure-sensitive adhesive layer). When the scratch-resistant layer 7 is a film having a hard coat layer or a film having scratch resistance and the infrared absorbing layer 6 is an adhesive layer, the scratch-resistant layer 7 may be laminated to the film heater 8 via the infrared absorbing layer 6.

[0117] Although not shown, in this embodiment, a transparent heat insulating layer may be laminated on the inner surface of the scratch-resistant layer 7. The transparent heat insulating layer is a layer that, due to its heat insulating properties, prevents the temperature of the heated film heater 8 and the infrared absorbing layer 6 from decreasing.

[0118] Here, the housing 3 may be made of a material having thermal insulation properties or may include a member having thermal insulation properties, thereby improving the heat retention of the air surrounded by the housing 3 and the transparent cover member 4 and suppressing a decrease in the temperatures of the film heater 8 and the infrared absorption layer 6 that have generated heat.

[0119] The configurations, materials, alternative forms, etc. of the members and elements other than the film heater 8 are the same as those of the LED lamp 1 according to the first embodiment described above.

[0120] In the LED lamp 1A according to this embodiment, when power is supplied to the film heater 8 from an external source, the film heater 8 generates heat. When power is supplied to the LED lamp unit 2 from an external source, the LED elements 21 emit light. The light is reflected by the reflector 22 and emitted forward through the lens 23. When the LED lamp unit 2 emits light in this manner, the infrared absorbing layer 6 absorbs the infrared rays contained in the light and generates heat. The heat generated by the film heater 8 is conducted to the transparent cover member 4 via the weather-resistant layer 5, and the heat generated by the infrared absorbing layer 6 is conducted to the transparent cover member 4 via the film heater 8 and the weather-resistant layer 5, thereby heating the transparent cover member 4. As a result, even if snow, ice, or condensation droplets adhere to the transparent cover member 4, the snow, ice, water droplets, etc. can be removed by the heated transparent cover member 4. As a result, the light from the LED lamp unit 2 is prevented from being blocked by snow, ice, water droplets, etc. adhering to the transparent cover member 4.

[0121] In this embodiment, since the film heater 8 and the infrared absorbing layer 6 are provided as heat-generating members, even if the heat generation amount of one is small, the heat generation amount of the other complements it, making it easy to obtain a sufficient heat generation amount and enabling effective removal of ice, snow, and water droplets. In particular, even if the heat generation amount of the film heater 8 is set to be small, a sufficient heat generation amount can be obtained by the heat generation of the infrared absorbing layer 6.

[0122] In this embodiment, the laminate having the weather-resistant layer 5, the film heater 8, the infrared absorbing layer 6, and the scratch-resistant layer 7 can be attached to the transparent cover member 4, for example, by a fastening member, without using an adhesive or the like.

[0123] In other embodiments, the positional relationship between the film heater 8 and the infrared absorbing layer 6 may be reversed, or the film heater 8 and the infrared absorbing layer 6 may be provided in a spaced-apart state.

[0124] In another embodiment, the infrared absorbing layer 7 may be laminated on the outside of the transparent cover member 4. In this case, for example, the layers may be laminated in the following order: transparent cover member 4 / infrared absorbing layer 7 / weather-resistant layer 5 / scratch-resistant layer 8, and a transparent heat insulating layer may be interposed between the infrared absorbing layer 7 and the weather-resistant layer 5, or between the weather-resistant layer 5 and the scratch-resistant layer 8. Even in such an embodiment, the weather-resistant layer 5 and / or the scratch-resistant layer 8 (and the transparent heat insulating layer) may be omitted.

[0125] In yet another embodiment, the infrared absorbing layer 6 may be provided apart from the transparent cover member 4 without being laminated thereon. For example, a member supporting the infrared absorbing layer 6 (and other layers) may be disposed between the transparent cover member 4 and the lens 23 of the LED lamp unit 2. Even in this case, the heat generated by the infrared absorbing layer 6 can be conducted to the transparent cover member 4 via the air surrounded by the housing 3 and the transparent cover member 4. Similarly, the film heater 8 may be provided apart from the transparent cover member 4 without being laminated thereon.

[0126] In yet another embodiment, the infrared absorbing layer 7 may be disposed in a location other than between the transparent cover member 4 and the lens 23 of the LED lamp unit 2, where the layer is exposed to light (infrared rays) from the LED lamp unit 2. Even in this case, the heat generated by the infrared absorbing layer 7 can be conducted to the transparent cover member 4 via the air surrounded by the housing 3 and the transparent cover member 4. In this embodiment, the infrared absorbing layer 7 does not have to be transparent.

[0127] In yet another embodiment, the infrared absorbing layer 7 may be provided inside the LED lamp unit 2 .

[0128] In the LED lamp of the second embodiment, the infrared absorbing layer 7 is omitted from the LED lamp 1 according to the above embodiment. On the other hand, the transparent cover member 4 has the function of absorbing infrared rays from the LED lamp unit 2 and generating heat.

[0129] In this configuration, when power is supplied to the film heater 8 from the outside, the film heater 8 generates heat, thereby heating the transparent cover member 4. Furthermore, when the LED lamp unit 2 emits light, the transparent cover member 4 absorbs the infrared rays contained in the light and generates heat. By heating and generating heat in this way, even if snow, ice, or condensation droplets adhere to the transparent cover member 4, the snow, ice, droplets, etc. can be removed by the heated and generated transparent cover member 4. As a result, the light from the LED lamp unit 2 is prevented from being blocked by snow, ice, droplets, etc. that adhere to the transparent cover member.

[0130] The transparent cover member 4 is usually made of transparent plastic or glass, and in this embodiment, an infrared absorbing material is kneaded into these materials. The type and content of the infrared absorbing material are the same as those in the above-mentioned embodiment.

[0131] The transparent cover member 4 also preferably contains additives such as additives that prevent yellowing and additives that impart weather resistance.

[0132] In the LED lamps 1 and 1A according to this embodiment, the temperature of the outer surface of the transparent cover member 4 15 minutes after the LED lamp unit 2 is turned on in a 0°C environment is preferably 20 to 100°C, more preferably 30 to 95°C, particularly preferably 40 to 90°C, and even more preferably 50 to 85°C, with 60 to 80°C being preferred. By enabling the LED lamp unit 2 to emit light and heat up in a short time even in a low-temperature environment, snow, ice, or condensation droplets adhering to the transparent cover member 4 can be efficiently removed. In this embodiment, an infrared-absorbing member capable of satisfying the above temperature conditions is preferably used, and the infrared-absorbing layer 6 described above is particularly preferably used.

[0133] In a 0°C environment, the temperature of the outer surface of the transparent cover member 4 30 minutes after the LED lamp unit 2 is turned on is preferably 20 to 100°C, more preferably 30 to 95°C, particularly preferably 40 to 90°C, even more preferably 50 to 85°C, and most preferably 60 to 80°C. In this way, by turning on the LED lamp unit 2 to emit light and raising the temperature in a short period of time even in a low-temperature environment, snow, ice, or condensation droplets that adhere to the transparent cover member 4 can be efficiently removed. In this embodiment, an infrared-absorbing member that can satisfy the above temperature conditions is preferably used, and the above-mentioned infrared-absorbing layer 6 is particularly preferably used.

[0134] In the LED lamps 1 and 1A according to the present embodiment, the difference (T1-T0) between the temperature (°C; T0) of the outer surface of the transparent cover member 4 when the LED lamp unit 2 is turned on in a 0°C environment and the temperature (°C; T1) of the outer surface of the transparent cover member 4 15 minutes after the light emission is preferably 20 to 100°C, more preferably 30 to 95°C, particularly preferably 40 to 90°C, and even more preferably 45 to 85°C, with 50 to 80°C being particularly preferred. This facilitates realizing a configuration in which the LED lamp unit 2 is turned on and heated in a short time even in a low-temperature environment, and even if snow, ice, or condensation droplets adhere to the transparent cover member 4, they can be efficiently removed. In this embodiment, an infrared-absorbing member that can satisfy the above temperature conditions is preferably used, and the above-described infrared-absorbing layer 6 is particularly preferably used.

[0135] In a 0°C environment, the difference (T2-T0) between the temperature (°C; T0) of the outer surface of the transparent cover member 4 when the LED lamp unit 2 is turned on and the temperature (°C; T2) of the outer surface of the transparent cover member 4 30 minutes after the light emission is preferably 20 to 100°C, more preferably 30 to 95°C, particularly preferably 40 to 90°C, and even more preferably 50 to 85°C, with 55 to 80°C being particularly preferred. This makes it easier to realize a configuration in which the LED lamp unit 2 is turned on and the temperature rises in a short time even in a low-temperature environment, and even if snow, ice, or condensation droplets adhere to the transparent cover member 4, they can be efficiently removed. In this embodiment, an infrared-absorbing member that can satisfy the above temperature conditions is preferably used, and in particular, the above-mentioned infrared-absorbing layer 6 is preferably used.

[0136] The above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0137] In this specification, when it is stated that "X to Y" (X and Y are any numbers), it means "X or more and Y or less" unless otherwise specified, and also means "preferably greater than X" or "preferably smaller than Y". Furthermore, when it is stated that "X or more" (X is any number), it means "preferably greater than X" unless otherwise specified, and when it is stated that "Y or less" (Y is any number), it also means "preferably smaller than Y" unless otherwise specified.

[0138] The present invention will be explained in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0139] Example 1 1. Preparation of Infrared-Absorbing Layer Forming Composition 50 parts by mass (based on solids content; the same applies hereinafter) of dipentaerythritol pentaacrylate and 50 parts by mass of dipentaerythritol hexaacrylate as the curable resin (A) serving as a binder, 5.0 parts by mass of 2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propane as the photopolymerization initiator (B), and 330 parts by mass of cesium tungsten oxide (C1; manufactured by Sumitomo Metal Mining Co., Ltd., product name "YMF-02AS") as the infrared absorber (C) were mixed, thoroughly stirred, and diluted with propylene glycol monomethyl ether to obtain a coating solution of an infrared-absorbing layer forming composition.

[0140] 2. Formation of Infrared Absorbing Layer A polyethylene terephthalate (PET) film having a thickness of 38 μm was prepared as a substrate. The coating solution of the infrared absorbing layer forming composition prepared above was applied to one surface of the PET film at a concentration of 2.4 g / m. ２ The coating amount (solid content equivalent) was applied by a gravure coater.

[0141] After the coating, the composition was heated at 70°C for 1 minute to thoroughly remove the dilution solvent. Then, under a nitrogen atmosphere, the composition for forming the infrared absorbing layer was cured by irradiating ultraviolet light using an ultraviolet irradiator (manufactured by GS Yuasa Corporation, product name "Nitrogen-purged small conveyor-type UV irradiator CSN2-40") under the following conditions to form an infrared absorbing layer, thereby obtaining a PET film with an infrared absorbing layer. The content of the infrared absorbent in the infrared absorbing layer was 1.43 mmol / m. ２ It was.

[0142] [Ultraviolet light irradiation conditions] Light source: high-pressure mercury lamp Lamp power: 1.4 kW Conveyor speed: 1.2 m / min Illuminance: 120 mW / cm ２ ・Light amount: 240mJ / cm ２

[0143] 3. Preparation of Pressure-Sensitive Adhesive Composition 44.9 parts by mass of n-butyl acrylate, 44 parts by mass of isobutyl acrylate, 5 parts by mass of vinyl acetate, 0.1 parts by mass of methacrylic acid, and 6 parts by mass of 2-hydroxyethyl methacrylate were polymerized by solution polymerization to obtain a (meth)acrylic acid ester polymer. The weight-average molecular weight of the (meth)acrylic acid ester polymer was measured and found to be 500,000 (value calculated as standard polystyrene by gel permeation chromatography (GPC)).

[0144] 100 parts by mass of the obtained (meth)acrylic acid ester polymer and 0.9 parts by mass of an isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, Inc., product name "Takenate D-101E") were mixed in toluene as a solvent to obtain a coating solution of a pressure-sensitive adhesive composition.

[0145] The adhesive composition solution prepared above was applied to the release-treated surface of a release sheet (thickness: 38 μm) prepared by treating one side of a polyethylene terephthalate film with a silicone-based release agent using a die coater, and the coating was heated at 90°C for 1 minute to thoroughly remove the solvent. The coating was then aged for 7 days at 23°C and 50% RH to form an adhesive layer with a thickness of 8 μm.

[0146] The pressure-sensitive adhesive layer and the surface of the PET film with an infrared-absorbing layer on which the infrared-absorbing layer was not formed were bonded together so as to be in contact with each other, thereby obtaining an infrared-absorbing laminate having a configuration of infrared-absorbing layer / substrate / pressure-sensitive adhesive layer / release sheet.

[0147] Here, the formulations (solid content equivalent) of the infrared absorbing layer forming compositions when the curable resin (A) is taken as 100 parts by mass (solid content equivalent) are shown in Table 1. The details of the abbreviations and the like shown in Table 1 are as follows. [Curable resin (A)] DPPA: Dipentaerythritol pentaacrylate DPHA: Dipentaerythritol hexaacrylate [Infrared absorber (C)] C1: Cesium tungsten oxide (manufactured by Sumitomo Metal Mining Co., Ltd., product name "YMF-02AS") C2: Lanthanum hexaboride (manufactured by Sumitomo Metal Mining Co., Ltd., product name "KHF-7AH")

[0148] [Examples 2 to 5] Infrared absorbing laminates were produced in the same manner as in Example 1, except that the type and amount (content) of the infrared absorber (C) in the infrared absorbing layer forming composition and the coating amount of the infrared absorbing layer forming composition were changed as shown in Table 1.

[0149] Comparative Example 1 Comparative Example 1 was prepared by not using the infrared absorbing laminate produced in the Examples in the measurement of heat generation temperature (Test Example 6) and evaluation of heat generation effect (Test Example 7) described below.

[0150] [Test Example 1] The release sheet was peeled off from the infrared-absorbing laminate produced in the example, and the infrared-absorbing laminate was attached to a 2 mm thick transparent polycarbonate plate (PC plate) via the exposed pressure-sensitive adhesive layer, and this was used as a measurement sample. For this measurement sample, background measurement was performed using the PC plate, and then the total light transmittance (%) was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SH-7000") in accordance with JIS K7361-1:1997. The results are shown in Table 2.

[0151] Test Example 2 (Haze Value Measurement) A measurement sample was prepared in the same manner as in Test Example 1. After background measurement was performed on the measurement sample using a PC board, the haze value (%) was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SH-7000") in accordance with JIS K7136:2000. The results are shown in Table 2.

[0152] Test Example 3 (Measurement of Lightness L*) Measurement samples were prepared in the same manner as in Test Example 1. After background measurement was performed on the measurement samples using a PC board, the lightness L* defined by the CIE 1976 L*a*b* color system was measured using a simultaneous photometric spectrophotometer colorimeter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SQ2000"). The results are shown in Table 2.

[0153] Test Example 4 (Measurement of Light Transmittance) The release sheet was peeled off from the infrared-absorbing laminate produced in the example, and the infrared-absorbing laminate was attached to a 3 mm-thick soda-lime glass plate via the exposed pressure-sensitive adhesive layer, which was used as a measurement sample. For this measurement sample, background measurement was performed using the soda-lime glass plate, and then the light transmittance (%) at a wavelength of 850 nm was measured using an ultraviolet-visible-near-infrared spectrophotometer (manufactured by Shimadzu Corporation, product name "UV-VIS-NIR SPECTROPHOTOMETER UV-3600"). The measurement was performed using the attached large sample chamber MPC-3100 without using the built-in integrating sphere. The results are shown in Table 2.

[0154] [Test Example 5] (Measurement of absorbance) The release sheet was peeled off from the infrared-absorbing laminate produced in the example, and the resulting product was used as a measurement sample. The measurement sample was measured for absorbance at a wavelength of 850 nm using an ultraviolet-visible-near-infrared (UV-Vis-NIR) spectrophotometer (manufactured by Shimadzu Corporation, product name "UV-3600", optical path length 10 mm). The results are shown in Table 2.

[0155] [Test Example 6] (Measurement of Heat Generation Temperature) A rectangular parallelepiped cover measuring 90 mm long x 120 mm wide x 30 mm high was made using a 2 mm thick transparent PC board, and placed over an infrared (IR) lamp (manufactured by ITEC Systems, product name "LFSL12N") to seal the IR lamp. At this time, the distance between the top surface of the IR lamp and the top surface of the cover's top plate was 30 mm. The wavelength of the IR lamp was 850 nm, and the irradiation intensity was 10 mW / cm. ２ It was decided.

[0156] Meanwhile, a measurement sample was prepared in the same manner as in Test Example 1. The measurement sample was placed on the top surface of the cover so that the infrared absorbing layer of the infrared absorbing laminate was in contact with the top surface of the cover. The atmosphere was set to 0°C, and an IR lamp was irradiated. The temperature of the top surface of the PC board of the measurement sample (the surface opposite the infrared absorbing layer) was measured immediately after irradiation, 15 minutes after irradiation, and 30 minutes after irradiation. In Comparative Example 1, the temperature of the top surface of the cover's top plate was measured. Based on the obtained measured values, the difference value (temperature difference) was calculated by subtracting the temperature immediately after irradiation from the temperature 15 minutes after irradiation, and the difference value (temperature difference) was calculated by subtracting the temperature immediately after irradiation from the temperature 30 minutes after irradiation. The respective results are shown in Table 2.

[0157] [Test Example 7] (Evaluation of Heat-Generating Effect) Using the same configuration as Test Example 6, the atmosphere was set to 0°C, and four cube-shaped ice blocks (30 mm x 20 mm x 20 mm) or the same amount of ice blocks finely shaved into shaved ice were placed on the measurement sample. In Comparative Example 1, the ice blocks / shaved ice were placed on the top surface of the cover's top plate. An IR lamp was then irradiated, and the state of the ice blocks and shaved ice was observed over time. The heat-generating effect of the infrared absorbing layer was evaluated based on the following criteria. The results are shown in Table 2. ◯: The ice blocks melted within 40 minutes, and the shaved ice melted within 20 minutes. ×: The ice blocks did not melt within 40 minutes, or the shaved ice did not melt within 20 minutes.

[0158]

[0159]

[0160] As can be seen from Table 2, the infrared absorbing laminates (infrared absorbing layers) produced in the examples were excellent in heat generation effect when exposed to an IR lamp.

[0161] The LED lamp according to the present invention can be suitably used as, for example, an automobile headlamp (headlight).

[0162] REFERENCE SIGNS LIST 1, 1A... LED lamp 2... LED lamp unit 21... LED element 22... Reflector 23... Lens 3... Housing 31... Lamp unit support member 4... Transparent cover member 5... Weather-resistant layer 6... Infrared absorbing layer 7... Scratch-resistant layer 8... Film heater

Claims

1. An LED lamp that can be used in low-temperature environments, comprising: an LED lamp unit having an LED element; a housing that contains said LED lamp unit; and a transparent cover member that transmits light from said LED lamp unit, wherein an infrared absorbing member that absorbs infrared rays from said LED lamp unit and generates heat is provided in a position where the heat generated by said infrared absorbing member is conducted to said transparent cover member, and / or said transparent cover member itself absorbs infrared rays from said LED lamp unit and generates heat.

2. An LED lamp that can be used in low-temperature environments, comprising: an LED lamp unit having an LED element; a housing that contains said LED lamp unit; a transparent cover member that transmits light from said LED lamp unit; and a film heater, wherein said film heater is positioned so that heat generated by said film heater is conducted to said transparent cover member.

3. An LED lamp according to claim 2, characterized in that an infrared absorbing member that absorbs infrared rays from the LED lamp unit and generates heat is provided in a position where the heat generated by the infrared absorbing member is conducted to the transparent cover member, and / or the transparent cover member itself absorbs infrared rays from the LED lamp unit and generates heat.

4. The LED lamp according to claim 1 or 3, wherein the infrared absorbing member is transparent.

5. The LED lamp of claim 1 or 3, wherein the infrared absorbing member or the transparent cover member contains at least one infrared absorbing material selected from the group consisting of cesium tungsten oxide, lanthanum hexaboride, tin-doped indium oxide, and antimony-doped tin oxide.

6. The LED lamp according to claim 1 or 3, wherein the infrared absorbing member is provided between the LED lamp unit and the transparent cover member.

7. The LED lamp according to claim 1 or 3, wherein the infrared absorbing member is a layered infrared absorbing layer.

8. The LED lamp according to claim 7, wherein the infrared absorbing layer is laminated directly or indirectly on the transparent cover member.

9. The LED lamp according to claim 8, wherein the infrared absorbing layer is laminated on the transparent cover member on the side of the LED lamp unit.

10. The LED lamp according to claim 7, wherein a weather-resistant layer is laminated directly or indirectly on the infrared absorbing layer.

11. The LED lamp according to claim 7, wherein a scratch-resistant layer is laminated directly or indirectly on the infrared absorbing layer.

12. The LED lamp according to claim 7, wherein a heat insulating layer is laminated directly or indirectly on the infrared absorbing layer.

13. The infrared absorbing layer contains an infrared absorbing material, and the content of the infrared absorbing material in the infrared absorbing layer is 0.01 mmol / m per unit area of ​​the infrared absorbing layer. ２ Above, 100 mmol / m ２ The LED lamp according to claim 7, wherein:

14. The infrared absorbing layer is formed by applying a material constituting the infrared absorbing layer, and the amount of the material applied when applying the material constituting the infrared absorbing layer is 0.1 g / m ２ Above, 100g / m ２ The LED lamp according to claim 7, wherein:

15. The LED lamp according to claim 7, wherein the transmittance of the infrared absorbing layer for light having a wavelength of 850 nm is 0.1% or more and 50% or less.

16. The LED lamp according to claim 7, wherein the absorbance of the infrared absorbing layer at a wavelength of 850 nm is 0.1 or more and 5 or less.

17. The LED lamp according to claim 2, wherein the film heater is transparent.

18. The LED lamp according to claim 3, wherein the infrared absorbing member is a layered infrared absorbing layer, and the infrared absorbing layer and the film heater are laminated directly or indirectly.

19. The LED lamp according to claim 2, wherein the film heater is laminated directly or indirectly on the transparent cover member.

20. The LED lamp according to claim 19, wherein the film heater is laminated on the LED lamp unit side of the transparent cover member.

21. The LED lamp according to claim 2, wherein a weather-resistant layer is laminated directly or indirectly on the film heater.

22. The LED lamp according to claim 2, wherein a scratch-resistant layer is laminated directly or indirectly on the film heater.

23. The LED lamp according to claim 2, wherein a heat insulating layer is laminated directly or indirectly on the film heater.

24. The LED lamp according to claim 1 or 2, which is for use in a moving vehicle.

25. The LED lamp according to claim 1 or 2, characterized in that it is for use in buildings.

26. An LED lamp according to claim 1 or 2, which is for lighting purposes.

27. The LED lamp according to claim 1 or 2, which is used for signs.

28. The LED lamp according to claim 1 or 2, characterized in that it is used as a marker lamp.

29. The LED lamp according to claim 1 or 2, characterized in that it is used for traffic lights.

30. The LED lamp according to claim 1 or 2, which is used for a display.

31. The LED lamp according to claim 1 or 2, characterized in that it is for outdoor use.

32. The LED lamp according to claim 1 or 2, characterized in that it is for indoor use.