EP2924713A1

EP2924713A1 - Heater with visible light reducing optical film

Info

Publication number: EP2924713A1
Application number: EP14183059.6A
Authority: EP
Inventors: Masaaki TAKATSUKA
Original assignee: Toshiba Lighting and Technology Corp
Current assignee: Toshiba Lighting and Technology Corp
Priority date: 2014-03-25
Filing date: 2014-09-01
Publication date: 2015-09-30
Also published as: JP2015185442A

Abstract

A heater (1) includes a bulb (2), a filament (3), gas (4), and a multilayer film (5). The filament (3) is arranged along a tube axis on an inside (2a) of the bulb (2). The gas (4) is filled in the inside (2a) of the bulb (2). The multilayer film (5) is formed on an outer surface (2b) of the bulb (2). Average visible ray transmittance at a wavelength of 380 nm to 780 nm of the multilayer film (5) is equal to or lower than 24%. In the filament (3), a plurality of projecting sections (31a) projecting to an inner wall (2c) of the bulb (2) when viewed from the tube axis direction are formed in a circumferential direction and the tube axis direction.

Description

FIELD

Embodiments of the present invention described herein relate to a heater.

BACKGROUND

A heater including both functions for heating and illumination of a space such as the inside of a store has been used.
Since the heater is used for the heating of the space, a user present in the space can visually recognize the heater irrespective of presence or absence of lighting. The heater for the space heating irradiates light in a visible ray region into the space during heat generation. The heater for the space heating is required of performance of a heat source. However, depending on an environment of use, the heater for the space heating is required not to be glaring, that is, required of a so-called antiglare property.
It is an object of the embodiments to provide a heater that improves an antiglare property.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view showing a heater in an embodiment.
FIG. 2 is a sectional view showing the heater.
FIG. 3 is a front view showing a bulb.
FIG. 4 is a front view showing a filament.
FIG. 5 is a diagram showing a manufacturing procedure for the heater in the embodiment.
FIG. 6 is a diagram showing the manufacturing procedure in the embodiment.
FIG. 7 is a diagram showing the manufacturing procedure in the embodiment.
FIG. 8 is a diagram showing the manufacturing procedure in the embodiment.
FIG. 9 is an explanatory diagram showing electric characteristics of the heater.
FIG. 10 is an explanatory diagram showing comparison of a visible light amounts and an infrared ray amounts.
FIG. 11 is an explanatory diagram showing illuminance comparison.
FIG. 12 is a sectional view showing a modification of the heater in the embodiment.
FIG. 13 is a sectional view showing a modification of the heater in the embodiment.

DETAILED DESCRIPTION

A heater 1 according to an embodiment explained below includes a bulb 2, a filament 3, gas 4, and a multilayer film 5. The filament 3 is arranged along a tube axis on an inside 2a of the bulb 2. The gas 4 is filled in the inside 2a of the bulb 2. The multilayer film 5 is formed on an outer surface 2b of the bulb 2. Average visible ray transmittance at a wavelength of 380 nm to 780 nm of the multilayer film 5 is equal to or lower than 24%. In the filament 3, a plurality of first projecting sections 31a projecting to an inner wall 2c of the bulb 2 when viewed from a tube axis direction are formed in a circumferential direction and the tube axis direction. A plurality of second projecting sections 34a, 35a, and 8a projecting further to the inner wall 2c of the bulb 2 than the first projecting sections 31a when viewed from the tube axis direction are provided in the circumferential direction and the tube axis direction.
In the heater 1 according to the embodiment explained below, average visible ray transmittance at the wavelength of 380 nm to 780 nm of the bulb 2 and the multilayer film 5 formed on the outer surface 2b of the bulb 2 is equal to or lower than 22%.
In the heater 1 according to the embodiment explained below, the filament 3 is a metal wire wound in a spiral shape. The first projecting sections 31a and the second projecting sections 34 are formed of a singularity of the metal wire.
In the heater 1 according to the embodiment explained below, the filament 3 is a metal wire wound in a spiral shape, and the second projecting sections 8a are formed of one metal foil different from the metal wire.

Embodiment

An embodiment is explained with reference to FIGS. 1 and 2. FIG. 1 is a front view showing a heater in the embodiment. FIG. 2 is a sectional view of the heater in the embodiment. Note that FIG. 1 is a diagram in which a part of the heater in a tube axis direction is omitted. FIG. 2 is an A-A sectional view of FIG. 1.
The heater in this embodiment gives heat to an object and a space desired to be heated. As an example, the heater is used as a heating apparatus for a space in a store or the like. A heater 1 includes, as shown in FIG. 1, a bulb 2, a filament 3, gas 4, a multilayer film 5, metal foils 61 and 62, and outer leads 71 and 72.
The bulb 2 includes a tubular section 21, seal sections 22 and 23, a chip 24, and dimples 25. The bulb 2 is, for example, a long object that is formed of quartz glass, transparent, and uncolored and has large total length L compared with a tube diameter DO. A tube wall load of the bulb 2 is desirably equal to or smaller than 36 [W/cm²]. If the tube wall load exceeds 36 [W/cm²], for example, likelihood of fusing of the filament 3 increases. Further, a bulb temperature [°C] rises, the bulb 2 is deformed, and durability of the bulb 2 is deteriorated.
In the tubular section 21, the inside 2a is formed as an internal space. The filament 3 is arranged on the inside 2a.
The seal sections 22 and 23 are arranged at both ends in the tube axis direction of the tubular section 21. The seal sections 22 and 23 are sealing sections and seal the tubular section 21. The seal sections 22 and 23 in this embodiment are formed in a tabular shape by pinch seals. The seal sections 22 and 23 may be formed in a columnar shape by shrink seals.
The chip 24 is a burn-off notch of an exhaust pipe 24' (see FIG. 3) provided to perform exhaust of the inside 2a and charging of the gas 4 during manufacturing of the heater 1. The chip 24 is closed during completion of the heater 1.
As shown in FIG. 2, the dimples 25 project to the inside 2a of the bulb 2 on the outer surface 2b of the bulb 2. An inner diameter DI' of the bulb 2 in a position where the dimple 25 is formed is smaller than an inner diameter DI of the bulb 2 in a position where the dimples 25 are not formed. Therefore, in the positions where the dimples 25 are formed, a gap between an inner wall 2c of the bulb 2 and the filament 3 is small. Therefore, it is possible to regulate rotation in the circumferential direction of the filament 3 with respect to the bulb 2 and movement of the bulb 2 in the tube axis direction. It is possible to suppress a dense portion and a sparse portion of the filament 3 from being formed in the tube axis direction. Consequently, it is possible to suppress non-uniformity of a visible light amount and an infrared ray amount in the tube axis direction of the heater 1. At least one dimple 25 only has to be formed. However, to regulate movement of the filament 3 according to the shapes of the bulb 2 and the filament 3, two or more dimples 25 may be formed as in this embodiment. The dimple 25 does not have to be formed.
The filament 3 is arranged along the tube axis on the inside 2a of the bulb 2. Amain section 31, leg sections 32 and 33, and anchor sections 34 are integrally formed. The filament 3 in this embodiment is a metal wire made of tungsten.
The main section 31 is a section that generates heat and emits light during lighting. The main section 31 is arranged on the inside 2a of the bulb 2. The main section 31 is formed by winding the metal wire. In the main section 31, a plurality of first projecting sections 31a projecting to the inner wall 2c of the bulb 2 when viewed from the tube axis direction are formed along the circumferential direction and the axial direction. That is, the plurality of first projecting sections 31a are arranged in a spiral shape along the tube axis direction. The first projecting sections 31a of the main section 31 in this embodiment are formed by bending the metal wire to be fit in a circle having an outer diameter DF1 centering on a center O1 of the filament 3. In the main section 31, the plurality of projecting sections 31a are arranged at substantially equal intervals in the circumferential direction when viewed from the tube axis direction. The main section 31 is formed by coupling the respective first projecting sections 31a using coupling sections 31b. Two coupling sections 31b, 31b coupled to one first projecting section 31a are coupled to ends (ends most spaced apart from each other) of the first projecting sections 31a adjacent to each other in the circumferential direction. The main section 31 of the filament 3 is formed as a so-called flower-winding coil.
The leg sections 32 and 33 are arranged at both ends in the tube axis direction of the main section 31. Parts of the leg sections 32 and 33 are arranged to be embedded in the seal sections 22 and 23. The leg sections 32 and 33 are sections that supply electric power to the main section 31. One ends of the leg sections 32 and 33 are respectively connected to both the ends of the main section 31 and the other ends are respectively electrically connected to the metal foils 61 and 62.
The anchor sections 34 suppress the center O1 of the filament 3 from separating from the center 02 of the bulb 2 because the filament 3 drops with its own weight. That is, the anchor sections 34 suppress the main section 31 from coming into contact with or coming close to the inner wall 2c of the bulb 2 as a whole. The anchor sections 34 are provided in a plurality of places of the main section 31 in the tube axis direction. Each of the anchor sections 34 is configured from one or more second projecting sections 34a. That is, a plurality of second projecting sections 34a are provided in the tube axis direction. When each of the anchor sections 34 are configured by the plurality of second projecting sections 34a, the plurality of second projecting sections 34a are arranged to be spaced apart from one another in the circumferential direction when viewed from the tube axis direction. For example, the second projecting sections 34a of one anchor section 34 may be arranged to be dotted at equal intervals or unequal intervals in the entire circumference in the circumferential direction when viewed from the tube axis direction. The second projecting sections 34a of the plurality of anchor sections 34 may be arranged to be dotted at equal intervals or unequal intervals over the entire circumference in the circumferential direction when viewed from the tube axis direction.
The second projecting sections 34a in this embodiment are formed by bending one metal wire together with the first projecting sections 31a to be fit in a circle having an outer diameter DF2 centering on the center O1 of the filament 3. The second projecting sections 34a are a part of the first projecting sections 31a projecting to the outer side in the radial direction. The second projecting sections 34a are formed by being coupled to the first projecting sections 31a or the second projecting sections 34a by the coupling sections 31b. The outer diameter DF2 is set larger than the outer diameter DF1. Therefore, the second projecting sections 34a project further to the inner wall 2c of the bulb 2 than the first projecting sections 31a when viewed from the tube axis direction. A ratio DF2/DF1 is 1.19≤DF2/DF1≤1.23. In the tube axis direction, an occupancy ratio of the second projecting sections 34a with respect to the entire main section 31 (100%) is 2% to 10%. This is because, if the occupancy ratio is smaller than 2%, since the filament 3 drops with its own weight, the center O1 of the filament 3 separates from the center 02 of the bulb 2, the filament 3 comes into contact with an inner surface 2c of the bulb 2, and a bulb surface temperature rises. If the occupancy ratio exceeds 10%, since the main section 31 of the filament 3 decreases, a portion contributing to light emission decreases. Therefore, a light amount decreases. Further, a ratio DF2/DI is 0.875≤DF2/DI≤0.975. If DF2/DI is smaller than 0.875, a dimension difference between the bulb 2 and the filament 3 increases, a holding ability of the bulb 2 on the filament 3 is deteriorated, and backlash occurs in the filament 3. On the other hand, if DF2/DI is larger than 0.975, the dimension difference between the bulb 2 and the filament 3 decreases and work for inserting the filament 3 into the bulb 2 during manufacturing of the lamp 1 becomes difficult. Therefore, workability is deteriorated.
The gas 4 is filled in the inside 2a of the bulb 2. The gas 4 in this embodiment is an argon gas of about 0.8 atm containing a very small amount of dibromomethane (CH₂Br₂). The gas 4 is desirably gas having low heat conductivity. Specifically, the gas 4 only has to contain one kind among krypton, xenon, argon, neon, and the like or gas obtained by combining a plurality of kinds of the gases. Further, the gas 4 only has to contain one kind among bromine, iodine, and the like or a halogen substance obtained by combining a plurality of kinds of the elements.
The multilayer film 5 is formed on the outer surface 2b of the bulb 2. The multilayer film 5 is formed in a region of the tubular section 21 on the outer surface 2b. The multilayer film 5 is formed such that average visible ray transmittance at a wavelength of 380 nm to 780 nm of the multilayer film 5 is equal to or lower than 24%. The multilayer film 5 is formed such that average visible ray transmittance at the wavelength of 380 nm to 780 nm of the bulb 2 and the multilayer film 5 formed on the outer surface 2b of the bulb 2 is equal to or lower than 22%. In the multilayer film 5 in this embodiment, six layers are formed from the outer surface 2b by alternately vapor-depositing silicon oxide and iron oxide. The multilayer film 5 is visually recognized in gold during extinction of the heater 1.
As "the average visible ray transmittance at the wavelength of 380 nm to 780 nm of the bulb 2 and the multilayer film 5 formed on the outer surface 2b of the bulb 2 ", for example, concerning the bulb 2 including the multilayer film 5 formed on the outer surface 2b, transmittance of a visible ray wavelength region at the wavelength of 380 nm to 780 nm was measured at every 5 nm using a spectrophotometer V-570 of JASCO Corporation, an average of the transmittance in the range of the wavelength of 380 nm to 780 nm was calculated, and a numerical value of the average was set as average visible ray transmittance in the range of the wavelength of 380 nm to 780 nm. "The average visible ray transmittance at the wavelength of 380 nm to 780 nm of the multilayer film 5" can be calculated by, for example, a method explained below. First, glass having transmittance, thickness, and the like substantially equivalent to those of the bulb 2 is used as a measurement sample and transmittance in the visible ray wavelength region at the wavelength of 380 nm to 780 nm of the bulb 2 (or the equivalent glass) is measured at every 5 nm using the spectrophotometer V-570 of JASCO Corporation. Second, "transmittance data in the visible ray wavelength region at the wavelength of 380 nm to 780 nm of the multilayer film 5" can be calculated from "transmittance data in the visible ray wavelength region at the wavelength of 380 nm to 780 nm of the bulb 2 (or the equivalent glass) and "transmittance data in the visible ray wavelength region at the wavelength of 380 nm to 780 nm of the bulb 2 and the multilayer film 5 formed on the outer surface 2b of the bulb 2". An average in the range of the wavelength of 380 nm to 780 nm was calculated from "the transmittance data in the visible ray wavelength region at the wavelength of 380 nm to 780 nm of the multilayer film 5". A numerical value of the average was set as "the average visible ray transmittance in the range of the wavelength of 380 nm to 780 nm of the multilayer film 5".
If the average visible ray transmittance at the wavelength of 380 nm to 780 nm of the multilayer film 5 is higher than 24% (the average visible ray transmittance at the wavelength of 380 nm to 780 nm of the bulb 2 and the multilayer film 5 formed on the outer surface 2b of the bulb 2 is higher than 22%), this is undesirable because glare increase according to a visibility evaluation. On the other hand, if the average visible ray transmittance at the wavelength of 380 nm to 780 nm of the multilayer film 5 is equal to or lower than 24% (the average visible ray transmittance at the wavelength of 380 nm to 780 nm of the bulb 2 and the multilayer film 5 formed on the outer surface 2b of the bulb 2 is equal to or lower than 22%), the glare by the visibility evaluation is reduced. In particular, if the average visible ray transmittance at the wavelength of 380 nm to 780 nm is equal to or lower than 21% (the average visible ray transmittance at the wavelength of 380 nm to 780 nm of the bulb 2 and the multilayer film 5 formed on the outer surface 2b of the bulb 2 is equal to or lower than 19%), the glare by the visibility evaluation is not felt.
One ends of the metal foils 61 and 62 are connected to the leg sections 32 and 33 of the filament 3 and the other ends are connected to the outer leads 71 and 72. The metal foils 61 and 62 are respectively embedded in the seal sections 22 and 23. The metal foils 61 and 62 in this embodiment are molybdenum foils and are arranged along tabular surfaces of the seal sections 22 and 23.
The outer leads 71 and 72 connect the metal foils 61 and 62 and a not-shown power supply on the outside. One ends of the outer leads 71 and 72 are respectively connected to the metal foils 61 and 62. The other ends are exposed to the outside of the bulb 2. Parts of the outer leads 71 and 72 are respectively embedded in the seal sections 22 and 23. The other ends of the outer leads 71 and 72 are respectively inserted into not-shown connectors together with the seal sections 22 and 23, electrically connected to not-shown cables provided in the connector, and connected to a power supply via the cables. The outer leads 71 and 72 are molybdenum rods.
A manufacturing procedure for the heater 1 is explained. FIG. 3 is a front view showing the bulb. FIG. 4 is a front view showing the filament. FIG. 5 is a diagram showing a manufacturing procedure for the heater in the embodiment. FIG. 6 is a diagram showing the manufacturing procedure in the embodiment. FIG. 7 is a diagram showing the manufacturing procedure in the embodiment. FIG. 8 is a diagram showing the manufacturing procedure in the embodiment.
As shown in FIG. 3, the bulb 2 is the tubular section 21 as a whole before machining. The exhaust pipe 24' allows the inside 2a and the outside of the bulb 2 to communicate with each other. As shown in FIG. 4, the metal foils 61 and 62 and the outer leads 71 and 72 are connected to the filament 3 in advance by welding or the like.
First, as shown in FIG. 5, the filament 3 is inserted into the inside 2a of the bulb 2. The filament 3 is inserted into the inside 2a of the bulb 2 such that the metal foils 61 and 62 are located in positions where the seal sections 22 and 23 are scheduled to be formed.
Subsequently, as shown in FIG. 6, both ends of the bulb 2 are fused by a gas burner (not shown in the figure) and pinched by a pincher (not shown in the figure) to form the seal sections 22 and 23. Consequently, the main section 31 of the filament 3 is housed in the tubular section 21.
Subsequently, gas in the tubular section 21 is exhausted by the exhaust pipe 24'. The gas 4 is filled in the tubular section 21.
Subsequently, as shown in FIG. 7, the exhaust pipe 24' is fused and burnt off by the gas burner (not shown in the figure) to close the tubular section 21. The gas 4 is filled in the inside 2a of the bulb 2.
Subsequently, as shown in FIG. 8, in a position of the bulb 2 opposed to the main section 31 of the filament 3, the bulb 2 is softened by the gas burner (not shown in the figure) to form the dimple 25.
Subsequently, the multilayer film 5 is formed on the outer surface 2b of the bulb 2. In the region of the tubular section 21 on the outer surface 2b, silicon oxide is vapor-deposited on a first layer, a third layer, and a fifth layer and iron oxide is vapor-deposited on a second layer, a fourth layer, and a sixth layer from the bulb 2 side and the multilayer film 5 of six layers is formed. Consequently, the heater 1 shown in FIG. 1 is manufactured.
Test results of the heater 1, a conventional product, and a comparative product 1 are explained below. FIG. 9 is an explanatory diagram showing electric characteristics of the heater. FIG. 10 is an explanatory diagram showing comparison of a visible light amount and an infrared ray amount. The "visible light amount" is an integrated value of spectrophotometry at a wavelength of 380 nm to 780 nm. Specifically, the "visible light amount" is measured using a spectrometer MSR-7000N of Opto Research Corporation. The "infrared ray amount" is an integrated value of spectrophotometry at a wavelength of 780 nm to 2500 nm. Specifically, the "infrared ray amount" is measured using the spectrometer MSR-7000N of Opto Research Corporation. Values of both of the visible light amount and the infrared ray amount are set as 100% in the "conventional product". FIG. 11 is an explanatory diagram showing illuminance comparison.
A "present invention 1", which is the heater 1, a "present invention 2", the "conventional product", and the "comparative product 1" have a total length L of 337 mm, a tube diameter DO of 10 mm, an inner diameter DI of 8 mm, and an effective light emission length of 280 mm. As shown in FIG. 9, when heater power is 2500 W, a tube wall load is 36 W/cm², a heater voltage is 235 V, and a heater current is 10.6 A. The tube wall load is a value obtained by dividing the heater power by an inner surface area of the bulb 2. The inner surface area of the bulb 2 is calculated by the tube diameter DI mm x 3.14 (n) x the effective light emission length [mm].
In the "present invention 1", the main section 31 of the filament 3 is a flower-winding coil obtained by winding a thin wire having length of 7791 mm and a wire diameter of 0.375 mm such that the flower-winding coil has an outer diameter DF1 of 6.2 mm and an outer diameter DF2 of 7.4 mm. The multilayer film 5 includes six layers (a first layer, a third layer, and a fifth layer are silicon oxide having thickness of 0.7 µm, a second layer, a fourth layer, and a sixth layer are iron oxide having thickness of 0.6 µm, the average visible ray transmittance at the wavelength of 380 nm to 780 nm of the multilayer film 5 is 24%, and the average visible ray transmittance at the wavelength of 380 nm to 780 nm of the bulb 2 and the multilayer film 5 formed on the outer surface 2b of the bulb 2 is 22%). In the "present invention 2", the filament 3 is the same as the filament 3 in the "present invention 1". The multilayer film 5 includes eight layers (a first layer, a third layer, a fifth layer, and a seventh layer are silicon oxide having thickness of 0.7 µm, a second layer, a fourth layer, a sixth layer, and an eighth layer are iron oxide having thickness of 0.6 µm, the average visible ray transmittance at the wavelength of 380 nm to 780 nm of the multilayer film 5 is 21%, and the average visible ray transmittance at the wavelength of 380 nm to 780 nm of the bulb 2 and the multilayer film 5 formed on the outer surface 2b of the bulb 2 is 19%).
In the "conventional product", a main section of a filament is a turn coil obtained by winding a thin wire having length of 4337 mm and a wire diameter of 0.307 mm such that the turn coil has an outer diameter of 2.4 mm. The "conventional product" does not include the multilayer film 5. The average visible ray transmittance at the wavelength of 380 nm to 780 nm of the bulb 2 is 95%.
The "comparative product 1" is a turn coil obtained by winding a thin wire having length of 4337 mm and a wire diameter of 0.307 mm such that the turn coil has an outer diameter of 2.4 mm. A multilayer film is the multilayer film 5 of the "present invention 1" (the average visible ray transmittance at the wavelength of 380 nm to 780 nm of the multilayer film 5 is 24% and the average visible ray transmittance at the wavelength of 380 nm to 780 nm of the bulb 2 and the multilayer film 5 formed on the outer surface 2b of the bulb 2 is 22%). In a "comparative product 2", a filament is the filament of the "present invention 1" and the "present invention 2". A multilayer film includes two layers (a first layer is silicon oxide having thickness of 0.7 µm, a second layer is iron oxide having thickness of 0.6 µm, the average visible ray transmittance at the wavelength of 380 nm to 780 nm of the multilayer film 5 is 28%, and the average visible ray transmittance at the wavelength of 380 nm to 780 nm of the bulb 2 and the multilayer film 5 formed on the outer surface 2b of the bulb 2 is 26%). Ina"comparative product 3", a filament is the filament of the "comparative product 1". A multilayer film includes four layers (a first layer and a third layer are silicon oxide having thickness of 0.7 µm, a second layer and a fourth layer are iron oxide having thickness of 0.6 µm, the average visible ray transmittance at the wavelength of 380 nm to 780 nm of the multilayer film 5 is 26%, and the average visible ray transmittance at the wavelength of 380 nm to 780 nm of the bulb 2 and the multilayer film 5 formed on the outer surface 2b of the bulb 2 is 24%).
As shown in FIG. 10, in the "comparative product 1", compared with the "conventional product", the visible light amount can be reduced by 40% in a state in which the infrared ray amount is maintained. That is, the visible light amount can be reduced by the heater, the filament of which is the turn coil, including the multilayer film 5. Further, in the "present invention 1" and the "present invention 2", compared with the "conventional product" and the "comparative product 1", the visible light amount can be markedly reduced in a state in which the infrared ray amount is generally maintained. That is, the "present invention 1" and the "present invention 2" include both of the filament 3 including the main section 31 configured by the flower-winding coil and the multilayer film 5 (the average visible ray transmittance at the wavelength of 380 nm to 780 nm of the multilayer film 5 is 24% and the average visible ray transmittance at the wavelength of 380 nm to 780 nm of the bulb 2 and the multilayer film 5 formed on the outer surface 2b of the bulb 2 is 22%). Therefore, the antiglare property can be markedly improved. In particular, as in the "present invention 2", by forming the multilayer film 5 in eight layers, the antiglare property can be further improved.
As shown in FIG. 11, in the case of the illuminance comparison, a measurement distance from the heater was 300 mm and heater power was 2500 W. Illuminance was measured using a colors-illuminometer CL-200 of Konica Minolta Inc. Compared with the "conventional product", the "comparative product 1" can reduce the illuminance to about 67%. Compared with the "conventional product", the "comparative product 2" can reduce the illuminance to about 30%. Compared with the "conventional product", the "comparative product 3" can reduce the illuminance to about 20%. Compared with the "conventional product", the "present invention 1" can reduce the illuminance to about 14%. Compared with the "conventional product", the "present invention 2" can reduce the illuminance to about 7%. In the visibility evaluation, by setting the illuminance to 701x or less, it can be evaluated that the heater is not glaring. Therefore, since both of the "present invention 1" and the "present invention 2" include the filament 3 and the multilayer film 5, the average visible ray transmittance of which at the wavelength of 380 nm to 780 nm is equal to or lower than 24%, the "present invention 1" and the "present invention 2" can markedly improve the antiglare property. Further, in the visibility evaluation, by setting the illuminance to 351x or less, it can be further evaluated that the heater is not glaring. Therefore, the "present invention 2" can markedly improve the antiglare property. If it is attempted to coat the multilayer film with more than eight layers, film peeling occurs during heater lighting and the reliability of the heater is spoiled. Therefore, the multilayer film desirably includes eight layers at the maximum.
As explained above, in the filament 3 in which the plurality of projecting sections 31a projecting to the inner wall 2c of the bulb 2 when viewed from the tube axis direction are formed along the circumferential direction and the axial direction, since a large number of metal wires can be housed in the inside 2a of the bulb 2, it is possible to reduce the visible light amount and the illuminance. In the multilayer film 5, the average visible ray transmittance at the wavelength of 380 nm to 780 nm is equal to or lower than 24%. Therefore, compared with the average visible ray transmittance of 95% at the wavelength of 380 nm to 780 nm of the "conventional product", which is the bulb in which the multilayer film 5 is not formed, it is possible to reduce the visible light amount and the illuminance. Therefore, the heater 1 according to this embodiment can improve the antiglare property.
The multilayer film 5, the average visible ray transmittance of which at the wavelength of 380 nm to 780 nm is equal to or lower than 24%, is formed on the outer surface 2b of the bulb 2. Therefore, it is difficult to directly visually recognize the bulb 2 and the filament 3 from the outside during extinction of the heater 1. The multilayer film 5 is visually recognized in gold from the outside during extinction of the heater 1. The heater 1 according to this embodiment can improve a design property during extinction of the heater 1.
When the filament 3 is about to drop with its own weight, the second projecting sections 34a come into contact with the inner wall 2c of the bulb 2 earlier than the first projecting sections 31a. Therefore, compared with when the second projecting sections 34a are not formed on the filament 3, a region of the main section 31 that comes into contact with the inner wall 2c of the bulb 2 can be reduced. Therefore, it is possible to suppress a rise in a bulb surface temperature. Therefore, it is possible to suppress occurrence of discoloration of the multilayer film 5, swelling of the bulb 2, and the like and attain an increase in the life of the heater 1.
In the embodiment, the second projecting sections 34a are formed of one metal wire that forms the first projecting sections 31a. However, the second projecting sections 34a are not limited to this. FIG. 12 is a sectional view showing amodification of the heater in the embodiment. FIG. 13 is a sectional view showing a modification of the heater in the embodiment. For example, as shown in FIG. 12, the second projecting sections 35a may be formed of a metal wire different from the one metal wire that forms the first projecting sections 31a. An anchor section 35 includes the second projecting section 35a formed by being wound in a ring shape and a wound section 35b wound around the main section 31 in order to hold the second projecting section 35a on the main section 31. As shown in FIG. 13, the second projecting sections 8a may be formed of another metal foil different from the one metal wire that forms the first projecting sections 31a. An anchor member 8 is a metal foil such as a molybdenum foil. The entire outer circumference or parts of the outer circumference of the anchor member 8 are the second projecting sections 8a. The anchor member 8 in this embodiment is formed in a shape having vertexes (e. g. , a triangle or a square). The anchor member 8 includes the second projecting sections 8a, which are the vertexes of the anchor member 8, and an opening section 8b inserted into the main section 31 in order to hold the anchor member 8 on the main section 31.
In the embodiment, the silicon oxide and the iron oxide are used as the multilayer film 5. However, the multilayer film 5 is not limited to this. In the multilayer film 5, the average visible ray transmittance at the wavelength of 380 nm to 780 nm only has to be equal to or lower than 24%. Therefore, the multilayer film 5 may be formed by vapor-depositing other materials. Any material may be used as long as the average visible ray transmittance at the wavelength of 380 nm to 780 nm of the bulb 2 and the multilayer film 5 formed on the outer surface 2b of the bulb 2 is 22%. For example, the bulb 2 may be configured by a so-called ruby tube formed of quartz glass containing copper oxide or tin oxide. The multilayer film 5 may be formed on the outer side of the bulb 2 such that the average visible ray transmittance at the wavelength of 380 nm to 780 nm of the bulb 2 and the multilayer film 5 formed on the outer surface 2b of the bulb 2 is 22%.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.

Claims

A heater (1) comprising:
a bulb (2);

a filament (3) arranged along a tube axis on an inside (2a) of the bulb (2);

gas (4) filled in the inside (2a) of the bulb (2); and

a multilayer film (5) formed on an outer surface (2b) of the bulb (2), average visible ray transmittance at a wavelength of 380 nm to 780 nm of the multilayer film (5) being equal to or lower than 24%, wherein

in the filament (3), a plurality of first projecting sections (31a) projecting to an inner wall (2c) of the bulb (2) when viewed from a tube axis direction are formed in a circumferential direction and the tube axis direction, and

a plurality of second projecting sections (34a, 35a, and 8a) projecting further to the inner wall (2c) of the bulb (2) than the first projecting sections (31a) when viewed from the tube axis direction are provided in the circumferential direction and the tube axis direction.
The lamp (1) according to claim 1, wherein an average visible ray transmittance at the wavelength of 380 nm to 780 nm of the bulb (2) and the multilayer film (5) formed on the outer surface (2b) of the bulb (2) is equal to or lower than 22%.
The heater (1) according to claim 1 or 2 wherein
the filament (3) is a metal wire wound in a spiral shape, and
the first projecting sections (31a) and the second projecting sections (34a) are formed of a singularity of the metal wire.
The heater (1) according to claim 1 or 2, wherein
the filament (3) is a metal wire wound in a spiral shape, and
the second projecting sections (8a) are formed of one metal foil different from the metal wire.