JPH04357664A - Incandescent lamp - Google Patents

Abstract

PURPOSE:To improve efficiency and lifespan of an incandescent bulb provided with an infrared reflection visible light transmission film by specifying the relationship between the average outer diameter of the bulb and the average thickness of a bulb wall. CONSTITUTION:An infrared reflection visible light transmission film 9 is formed on the outer surface of a spherical or elliptic bulb 2. When a halogen bulb 1 is lighted and a filament 6 emits light thereby, the light transmits the bulb 2 and is injected into the film 9, while the infrared ray of 700-1300nm of the light is reflected, and mainly a visible light is transmitted. A relationship between an average outer diameter D of the bulb 2 and an average thickness (t) is 0.05<=t/D<=0.12. When the infrared ray emitted from the filament 6 is reflected by the film 9, the ray is directed to the center or the focal point of the bulb, and surely returns to the filament. By regulating the thickness of the bulb 2 through the above-mentioned expression, the influence of refractive index due to the thickness of a bulb wall is reduced, while the feedback ratio to the filament 6 is improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an incandescent light bulb having an infrared reflective and visible light transparent film formed on the outer surface of the bulb.

0002

[Prior Art] For example, spot downlights used in stores, etc. are designed to distinguish the illuminated products from other products and make them stand out. Colored light is preferred, which is why incandescent bulbs, especially halogen bulbs, are used as light sources. Such incandescent bulbs naturally have low lamp efficiency as more heat is emitted by the lamp, and this heat heats up the fixture and is emitted from them when a large number of such bulbs are used in the same room. The amount of heat generated by the air will be considerably large, placing a considerable burden on air conditioning equipment. therefore,
It is desirable for this type of incandescent light bulb to have improved lamp efficiency. In order to improve lamp efficiency, it has recently been proposed to form an infrared reflective and visible light transparent film on the outer surface of a light bulb.

[0003] This infrared reflective visible light transmitting film is formed of a multilayer light interference film, and transmits the visible light emitted from the filament housed in the bulb, but reflects the infrared light. It is designed to return infrared rays to the filament. The reflected infrared rays reheat the filament, and therefore the power supplied from the outside for the incandescent emission of the filament can be reduced, which has the advantage of improving luminous efficiency.

However, in the case of a lamp whose bulb shape is a cylindrical (T-shaped) bulb, the reflecting surface is cylindrical, so the infrared rays emitted from the filament pass through the infrared reflecting film formed on the outer surface of the cylindrical bulb. When reflected by
The infrared rays may be reflected in a direction away from the filament, and the proportion of infrared rays reflected by the infrared reflective film returning to the original filament is reduced. In order to capture infrared rays that are reflected away from the filament, the length of the filament must be increased, resulting in a high-voltage type.

On the other hand, if the bulb shape is made into a spherical (G-shaped) bulb or an ellipsoidal shape close to this, when the infrared rays emitted from the filament are reflected by the infrared reflecting film, basically the center or focal point of the bulb is towards the position and ensure a return to the filament. For this reason,
The infrared absorption efficiency of the filament is improved, and the luminous efficiency is improved.

Furthermore, since the reflected infrared rays are directed toward the center or focal point of the bulb, the infrared rays can be captured at a high rate even if the filament length is made small, resulting in a high infrared absorption efficiency.

However, when the shape of the bulb is spherical or elliptical, the light reflected by the infrared reflective film tries to return to the center of the bulb because it was originally emitted from the center or focal point of the bulb. , light emitted from a position eccentric from the center of the bulb is difficult to return to the center of the bulb. However, it is difficult to make the filament shape into a point light source, and the filament has no choice but to have a cylindrical shape called a C shape.

[0008]

[Problem to be solved by the invention] In other words, if the bulb is spherical, the efficiency will be higher than that of a cylindrical bulb, but even if the bulb is spherical, the filament will inevitably have a cylindrical shape. The light emitted from the end of the cylindrical filament, that is, the light emitted from a position away from the center of the bulb, may return to the filament at a low rate, and the efficiency may not improve as much as expected.

When an infrared reflecting and visible light transmitting film is formed on the inner surface of the bulb, the reflected infrared rays easily return to the filament because there is no effect of the wall thickness of the bulb. When a reflective visible light transmitting film is formed, the glass thickness of the bulb wall exists, so when passing through this glass, the direction of reflection of infrared rays is shifted due to the influence of the refractive index, and the infrared rays do not return to the filament. There are defects that affect lamp efficiency.

The present invention was made based on the above circumstances, and its purpose is to reduce the influence of the wall thickness of the bulb, improve the efficiency with which infrared rays are absorbed by the filament, and improve the luminous efficiency. The aim is to provide an incandescent light bulb that

[0011]

[Means for Solving the Problems] The present invention forms an infrared reflective visible light transmitting film on the outer surface of a bulb containing a filament, and reflects the infrared rays emitted from the filament by the infrared reflective visible light transmitting film. In the incandescent light bulb that returns to the filament, the bulb is formed into a spherical or approximately elliptical shape, and the relationship between the average outer diameter D and the average wall thickness t of the bulb is 0.05≦t/D. ≦0
．． 12.

0012

[Operation] According to the present invention, since the bulb shape is spherical or ellipsoidal, when the infrared rays emitted from the filament housed in the bulb are reflected by the infrared reflecting film, they are directed toward the center or focal point of the bulb. It will definitely return to the filament. In this case, since the wall thickness of the bulb is regulated, the influence of the refractive index due to the wall thickness of the bulb can be reduced, the feedback rate of infrared rays can be increased, and the lamp efficiency and lamp life can be improved.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on an embodiment shown in the drawings.

In the figure, 1 is a halogen light bulb, and this halogen light bulb 1 has a spherical (G-shaped bulb) bulb 2 made of quartz glass. The spherical valve 2 has an outer diameter D of 8
~15 mm, for example, in the case of a 12V, 50W type, the bulb diameter D is made of transparent quartz glass of 10 mm, and the wall thickness t is, for example, about 0.6 mm. A crush sealing portion 3 is formed at one end of the valve 2 . This halogen light bulb 1 operates at a low voltage, for example, about 6 to 36 V, and a pair of metal foil conductors 4, 4 made of molybdenum or the like are sealed to the sealing part 3. is connected to internal lead-in lines 5, 5. These internal lead-in wires 5, 5 are guided into the bulb 2, and a filament 6 made of a tungsten coil is installed between both ends thereof. The filament 6 is arranged so that the coil axis is along and above the bulb axis, that is, a C-shaped filament is adopted. The coil diameter d of the filament 6 is d for the above 12V, 50W type lamp.
= approximately 1.2 mm, and the coil length n is approximately 4 mm. External lead-in wires 7, 7 are connected to a pair of metal foil conductors 4, 4 sealed in the sealing portion 3. In the above configuration, the relationship between the average outer diameter D of the bulb and the average wall thickness t of the bulb is set as follows. 0.05≦t/D≦0.12 (1) The valve 2 is filled with argon gas at a predetermined pressure and halogen such as a bromine compound.

An infrared reflective and visible light transmitting film 9 is formed on the outer surface of the bulb 2. This infrared reflective visible light transmitting film 9 is an optical interference film, which is well known and is not shown in the drawings, but is constructed by alternately layering high refractive index layers and low refractive index layers, for example, as a multilayer film with a total of 9 to 17 layers. It has the property of reflecting infrared rays but transmitting visible light. The high refractive index layer is made of titanium oxide (TiO2), tantalum oxide (Ta2O5), zirconium oxide (ZrO2)
, zinc sulfide (ZnS), etc., and the low refractive index layer is made of silicon oxide (silica=SiO2), magnesium fluoride (MgF2), etc.

[0016] The operation of the halogen light bulb having such a structure will be explained. When the halogen bulb 1 is turned on and the filament 6 emits light, this light passes through the bulb 2. The light transmitted through the bulb 2 enters an infrared reflective visible light transmitting film 9 formed on the outer surface of the bulb 2. Of the light that reaches this infrared reflective visible light transmitting film 9, for example, 700 to 1300 nm
The light in the infrared region m is reflected by this infrared reflective visible light transmitting film 9, and mainly visible light is transmitted.

The reflected infrared rays are returned to the filament 6, so that the filament 6 is heated again by the reflected infrared rays, thereby reducing power consumption and improving luminous efficiency.

In this case, as shown in FIG. 2(a),
The light A emitted from the bulb center point O or its vicinity is
The bulb 2 has a spherical shape, and the infrared reflective visible light transmitting film 9 formed on the outer surface is also arranged in a substantially spherical shape.
The infrared rays reflected by this infrared reflective visible light transmitting film 9 are directed toward the center of the bulb 2. Therefore, the infrared rays are reliably returned to the filament 6 disposed at the center of the bulb 2, that is, the return efficiency of the infrared rays is good.

On the other hand, if an infrared reflective visible light transmitting film is formed on the inner surface of the bulb, the infrared light B emitted from the end of the filament 6 will be reflected by this infrared reflective visible light transmitting film. The other end of the filament 6 is reached as indicated by the broken line C. However, since the infrared reflective visible light transmitting film 9 is formed on the outer surface of the bulb 2, the light B emitted from the end of the filament 6 passes through the bulb wall and passes through the infrared reflective film on the outer surface, as shown by the solid line. When the light is reflected by the light beam 9 and returned into the bulb 2, the incident position is shifted. Therefore, the other end of the filament 6 is not reached.

To explain this point in detail with reference to FIG. 2(b), when the light emitted from the filament 6 enters the bulb wall at a point P on the inner surface of the bulb 2, the incident angle α and the refraction angle β at this point are is Snell's law, no sin α=ng
Due to the relationship of sin β (where no is the refractive index of the gas inside the bulb, and ng is the refractive index of the quartz glass), the light no longer travels straight and reaches point Q with a deviation in direction. At point Q, infrared rays pass through the infrared reflective visible light transmitting film 9 due to the relationship of incident angle γ = reflection angle γ.
This reflected light travels within the bulb wall toward point R. At point R, similar to Snell's law above, from the relationship between the angle of incidence β and the angle of refraction α, ng sin β
=no sin α, it is refracted in the direction of B'. That is, the light that has entered the point P on the inner surface of the bulb 2 is returned into the bulb from the same point R on the inner surface, and the direction in which the light travels is shifted by an amount corresponding to the distance PR. Furthermore, in practice, transmission and reflection at each point P, Q, and R are not perfect, and multiple reflections occur in the infrared reflective and visible light transmitting film 9, resulting in complex reflection.

For this reason, some of the infrared rays emitted from the end of the filament 6 may not return to the filament 6. In other words, the feedback rate is low, which is one of the factors that hinders improvement in lamp efficiency. In addition, since infrared rays return intensively to the center of the filament 6, the center of the filament 6 is heated more intensively than the ends, causing problems such as early breakage and melting due to evaporation of tungsten. . Therefore, in this embodiment, the thickness of the bulb 2 is regulated to increase the rate at which the reflected infrared rays return to the filament 6. In other words,
By reducing the wall thickness t of the bulb 2, the previous distance PR can be reduced, the deviation in the path of the reflected infrared rays can be reduced, and the feedback rate can be increased.

However, if the wall thickness t is made too small, the mechanical strength of the valve will decrease and its life will be shortened. As a result of researching the optimal conditions, it was found that the equation (1) described above should be satisfied.

The above equation (1) has been confirmed through experiments, and the results of this experiment will be explained below. FIG. 3 is a characteristic diagram showing the results of examining how the lamp efficiency improvement rate and lamp life change when the ratio t/D of the bulb outer diameter D and the bulb wall thickness t changes. The lamp used is
12V, 50W type halogen bulb, bulb diameter D=
A spherical (G-shaped bulb) bulb 2 made of 10 mm transparent quartz glass was used. The filament 6 is a C-shaped filament, and the coil diameter d of the filament 6 is 1.2 m.
m, the coil length n was 4 mm. 3 in valve 2
Atmospheric argon gas and a bromine compound are sealed, and the outer surface of the bulb 2 is coated with titanium oxide (TiO2) and silicon oxide (S).
An external reflection/visible light transmission film 9 is formed of an alternating multilayer film of (iO2). With such a halogen bulb, if the wall thickness t of bulb 2 is 0.6 mm, the brightness will be approximately 90 mm.
0 lm, and the lifespan was 3000 hours.

FIG. 3 shows the relationship between efficiency and life when the valve wall thickness t is changed. In FIG. 3, characteristic 1 marked with an "open circle" indicates the efficiency improvement rate in the case of a spherical (G-shaped) valve that is the object of the present invention, and characteristic 2 marked with an "open triangle" indicates the efficiency improvement rate of the spherical (G-shaped) valve targeted by the present invention. The relative life of the target spherical (G-type) valve is shown. For comparison with the present invention, a cylindrical shape (T type) with an outer diameter of 8 mm was used.
An experiment was conducted using a halogen bulb using a bulb and a filament under the above conditions, and the wall thickness t was varied. In FIG. 3, characteristic 3 marked with a "black circle" indicates the efficiency improvement rate of a cylindrical (T-shaped) valve, and characteristic 4 marked with a "black triangle" indicates its relative life.

[0025] In a lamp with a cylindrical (T-shaped) bulb, the reflective surface is cylindrical, so when the infrared rays emitted from the filament are reflected by the infrared reflective film formed on the outer surface of the cylindrical bulb, they move away from the filament. Since the ratio of infrared rays reflected in the direction is large and the return rate of infrared rays reflected by the infrared reflective film is low, the improvement rate of lamp efficiency is only 4 to 5% at most, but in the case of spherical (G-shaped) bulbs, Lamp efficiency improvement rate is 30-40% due to improved infrared feedback rate.
It also improves.

However, as can be seen from FIG.
When the value of D exceeds 0.12, the wall thickness of the bulb 2 becomes relatively large, so the distance P-R in Fig. 2 becomes large, and the deviation of the reflected light becomes large, so the feedback rate of infrared rays decreases. ,
Therefore, no improvement in lamp efficiency can be expected, and furthermore, the center of the filament is heated intensively, resulting in a shortened lifespan. On the other hand, when the value of t/D becomes less than 0.5, the wall thickness of the bulb 2 becomes too small, it becomes difficult to maintain thermally, and the bulb becomes spherical (G-shaped).
This can cause problems such as bursting regardless of whether the valve is a cylindrical (T-shaped) valve or not. Therefore, it is preferable to satisfy 0.05≦t/D≦0.12 (1).

Note that the present invention is not limited to the above embodiments. That is, in the embodiment shown in FIG. 1, the case where the bulb 2 is spherical has been described, but the bulb may be an ellipsoid that is close to a sphere. When using an ellipsoidal bulb, the filament housed inside is arranged so that the coil axis is along the long axis of the ellipse, and the filament is located at the first and second focal points of the ellipse. , the bulb diameter D in this case corresponds to the bulb diameter at the midpoint of the focal position.

In the example of FIG. 1, the coil filament 6
Although an example of a lamp in which the coil axis is arranged along the bulb axis has been shown, the filament may be arranged in a direction perpendicular to the bulb axis at 90 degrees.

Furthermore, the light bulb used in the present invention is not limited to a halogen light bulb, but may be a general incandescent light bulb, and the end sealing structure is not limited to a crushed seal type, but may be a stem seal. You can.

[0030]

As explained above, according to the present invention, the bulb shape is spherical or ellipsoidal, so that when infrared rays emitted from the filament housed in the bulb are reflected by the infrared reflective film, the center of the bulb or This will ensure that it heads towards the focal point and returns to the filament. In this case, since the wall thickness of the bulb is regulated, the influence of the bulb wall thickness on the refractive index can be reduced, and the feedback rate to the filament is improved. Therefore, lamp efficiency and lamp life can be improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a halogen light bulb showing one embodiment of the present invention.

FIG. 2A and FIG. 2B are diagrams each illustrating how infrared rays are reflected in the same embodiment.

FIG. 3 is a diagram showing the lamp efficiency and life characteristics of the same example.

[Explanation of symbols]

1... Halogen light bulb, 2... Spherical bulb, 6... Filament, 9... Infrared reflective visible light transmitting film.

Claims (2)

[Claims] 1. An incandescent light bulb, wherein an infrared reflective and visible light transmitting film is formed on the outer surface of a bulb containing a filament, and infrared rays emitted from the filament are reflected by the infrared reflective and visible light transmitting film and returned to the filament. In the light bulb, the bulb has a spherical or substantially elliptical shape, and the relationship between the average outer diameter D of the bulb and the average wall thickness t of the bulb wall is 0.05≦t/D≦0.12. An incandescent light bulb that is characterized by 2. Claim 1, wherein the light bulb is a halogen light bulb in which halogen is sealed inside the bulb.
The incandescent light bulb described in.