JP3168588B2 - Incandescent light bulb - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art For example, a spot downlight used in a store or the like has a high color rendering property and a cool color to irradiate a product to be distinguished from other products so as to stand out, that is, to enhance a lighting effect. Color light is preferred, for which reason incandescent bulbs, in particular halogen bulbs, are used as light sources. Such incandescent lamps naturally have a low lamp efficiency when the heat emitted from the lamp is large, and this heat heats the fixture and is emitted from these lamps when a large number of such lamps are used in the same room. The amount of heat generated is considerably increased, which imposes a considerable burden on air conditioning equipment. Therefore,
For this kind of incandescent lamp, improvement in lamp efficiency is desired. In order to improve the lamp efficiency, it has recently been proposed to form an infrared-reflective visible light transmitting film on the outer surface of the bulb.

[0003] This infrared-reflective visible light transmitting film is formed of a multilayer light interference film and transmits visible light emitted from a filament housed in a bulb, but reflects infrared light. Infrared rays are returned to the filament. The reflected infrared rays reheat the filament, and therefore, there is an advantage that the power supplied from the outside for incandescent emission of the filament can be reduced, thereby improving the luminous efficiency.

However, when the valve shape is cylindrical (T
In the case of a lamp with a bulb, the reflective surface is cylindrical, so if the infrared radiation emitted from the filament is reflected by the infrared reflective film formed on the outer surface of the cylindrical bulb, it will be reflected away from the filament. And the ratio of infrared rays reflected by the infrared reflective film to return to the original filament is reduced. Then, in order to capture infrared rays reflected in a direction away from the filament, the length of the filament must be increased, and the length of the filament increases, resulting in a high voltage type.

On the other hand, when the bulb shape is a spherical (G-shaped) bulb or an ellipsoidal sphere close to the bulb, when the infrared ray emitted from the filament is reflected by the infrared reflecting film, the center or focus of the bulb is basically reached. Going in the direction of the position ensures that it returns to the filament. For this reason,
The infrared absorption efficiency of the filament is improved, and the luminous efficiency is improved.

[0006] Further, since the reflected infrared rays are directed toward the center of the bulb or the focal position, even if the filament length is reduced, the capture rate of the infrared rays is high, and the infrared absorption efficiency is increased.

However, when the bulb shape is spherical or elliptical sphere, the light reflected by the infrared reflection film tends to return to the center point of the bulb because of the light originally radiated from the center or the focal position of the bulb. Light emitted from a position decentered from the center of the bulb is unlikely to return to the center of the bulb. However, it is difficult to make the filament shape a point light source, and it must be a cylindrical shape called a C-shape.

[0008]

That is, when the bulb shape is spherical, the efficiency is higher than that of a cylindrical valve. However, even if the bulb is spherical, the filament shape is inevitably cylindrical. Light emitted from the end of the cylindrical filament, that is, light emitted from a position deviated from the center of the bulb, may return to the filament at a low rate, and the expected improvement in efficiency may not be expected.

When an infrared-reflective visible light transmitting film is formed on the inner surface of the bulb, the reflected infrared rays are easily returned to the filament because there is no influence of the thickness of the bulb wall. When a reflective visible light transmitting film is formed, the thickness of the glass wall of the bulb wall exists, so that when transmitted through this glass, the reflection direction of infrared rays is shifted due to the influence of the refractive index and does not return to the filament. There is a problem that affects the lamp efficiency.
By the way, if the wall thickness of the valve is made too small,
There is a problem that the service life is shortened.

The present invention has been made in view of such circumstances, and an object of the present invention is to reduce the influence of the thickness of the bulb, improve the efficiency of absorbing infrared rays into the filament, and increase the luminous efficiency. to improve the cause and co-Bal
Provide incandescent bulbs that can also improve lamp life
It is assumed that.

[0011]

According to the present invention, an infrared-reflective 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 visible light transmitting film. In the incandescent lamp which is returned to the filament, the bulb has a spherical or substantially elliptical bulb shape, and the relationship between the average outer diameter D and the average thickness t of the bulb is 0.05 ≦ t / D. ≤
0.12.

[0012]

According to the present invention, since the bulb shape is spherical or elliptical sphere, when the infrared ray emitted from the filament contained in the bulb is reflected by the infrared reflection film, it goes toward the center of the bulb or the direction of the focal position. Make sure to return to the filament. In this case, since the thickness of the bulb is regulated, the influence of the refractive index due to the thickness of the bulb wall can be reduced, the feedback rate of infrared rays can be increased, and the lamp efficiency and the lamp life can be improved.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to one embodiment shown in the drawings.

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

An infrared reflecting visible light transmitting film 9 is formed on the outer surface of such a bulb 2. The infrared-reflective visible light transmitting film 9 is a light interference film, and although not shown, a high-refractive-index layer and a low-refractive-index layer are alternately layered, although not shown, and are configured as a multilayer film of, for example, a total of 9 to 17 layers. Thus, it has the property of reflecting infrared light but transmitting visible light.
The high refractive index layer is made of titanium oxide (TiO ₂ ), tantalum oxide (Ta ₂ O ₅ ), zirconium oxide (ZrO ₂ ), zinc sulfide (ZnS), and the like, and the low refractive index layer is silicon oxide (silica = SiO _2). ), Magnesium fluoride (Mg
F ₂ ).

The operation of the halogen lamp having such a configuration will be described. 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 reaching the infrared reflective visible light transmitting film 9, for example, 700 to 1300 nm
The light in the infrared region is reflected by the 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, so that the power consumption is reduced and the luminous efficiency is improved.

In this case, as shown in FIG.
Light A emitted from or near the valve center point O is
Since 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 light reflected by the infrared-reflective visible light transmitting film 9 is directed to the center of the bulb 2. For this reason, the infrared rays are surely returned to the filament 6 disposed at the center of the bulb 2, that is, the infrared rays return efficiency is high.

On the other hand, the light B radiated from the end of the filament 6 is reflected by the infrared reflected visible light transmitting film if the infrared reflected visible light transmitting film is formed on the inner surface of the bulb. As shown by the broken line C, it reaches the other end of the filament 6. However, since the infrared-reflecting 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 bulb wall as shown by the solid line. When the light is reflected at 9 and returned into the bulb 2, the incident position shifts. For this reason, it does not reach the other end of the filament 6.

This point will be described in detail with reference to FIG. 2B. When light emitted from the filament 6 enters the bulb wall at the point P on the inner surface of the bulb 2, the incident angle α and the refraction angle β at this point are obtained. Snell's _{law, n o sin α = n g} sin β
(However, n _o is the refractive index of the gas in the bulb, n _g quartz refractive index of the glass) will not go straight from the relationship, reaches the point Q deviated the direction. At point Q, the infrared light is reflected by the infrared-reflective visible light transmitting film 9 in a relation of incident angle γ = reflection angle γ,
This reflected light travels in the bulb wall toward point R. In R point, as in the law of the Snell, by the relation of the refractive angle alpha and angle of incidence _{β n g sin β = n o} sin α, B
Is refracted in the direction of '. That is, P on the inner surface of the valve 2
The light incident on the point is also returned from the point R on the inner surface into the bulb, and the traveling direction of the light is shifted by an amount corresponding to the distance PR. Further, in practice, transmission and reflection at each of the points P, Q, and R are not perfect, and multiple reflections are made in the infrared-reflective visible light transmitting film 9, so that complicated reflections are made.

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 the improvement of the lamp efficiency. Further, since the infrared rays are intensively returned to the central portion of the filament 6, the central portion of the filament 6 is more intensively heated than the end portion, and there is a problem that the filament 6 is broken or melted earlier due to evaporation of tungsten or the like. . Therefore, in the present embodiment, the ratio of reflected infrared rays returning to the filament 6 is increased by regulating the thickness of the bulb 2. That is,
If the thickness t of the bulb 2 is reduced, the distance PR can be reduced, the deviation of the path of the reflected infrared rays can be reduced, and the feedback rate can be increased.

However, if the thickness t is made too small, the outer diameter becomes too small.
In relation to D, the mechanical strength of the valve is reduced, and the life is shortened. Therefore, as a result of studying the optimum conditions, it was found that the above-described equation (1) should be satisfied.

The above equation (1) has been confirmed by experiments, and the results of this experiment will be described below. FIG. 3 is a characteristic diagram showing the results of examining how the ratio between the bulb outer diameter D and the bulb wall thickness t and the rate of improvement in lamp efficiency and the lamp life change when t / D varies. The lamp used was a 12 V, 50 W type halogen bulb, and a spherical (G-shaped bulb) bulb 2 made of transparent quartz glass having a bulb diameter D = 10 mm. The filament 6 is a C-shaped filament, and the coil diameter d of the filament 6 is 1.2.
mm, and the coil length n was 4 mm. Argon gas and a bromine compound at 3 atm are sealed in the valve 2, and titanium oxide (TiO ₂ ) and silicon oxide (SiO ₂ ) are provided on the outer surface of the valve 2.
₂ ) An external reflection visible light transmitting film 9 composed of an alternating multilayer film is formed. In such a halogen bulb, when the thickness t of the bulb 2 was 0.6 mm, the brightness was about 900 lm and the life was 3000 hours.

FIG. 3 shows the relationship between the efficiency and the life when the valve thickness t is changed. In FIG. 3, the characteristic 1 of the “open circle” mark indicates the efficiency improvement rate in the case of the spherical (G-type) valve targeted by the present invention, and the characteristic 2 of the “open triangle” mark indicates the efficiency of the present invention. The relative life of a spherical (G-type) valve of interest is shown. For comparison with the present invention, a cylindrical type (T type) with an outer diameter of 8 mm
Using a bulb, the filament was tested on a halogen bulb under the above conditions, and the wall thickness t was changed. In FIG. 3, a characteristic 3 indicated by a “black circle” indicates the efficiency improvement rate of the cylindrical (T-type) valve, and a characteristic 4 indicated by a “black triangle” indicates the relative life.

Since the reflecting surface of the lamp of the cylindrical (T-type) bulb is cylindrical, when the infrared rays emitted from the filament are reflected by the infrared reflecting film formed on the outer surface of the cylindrical bulb, the lamp moves away from the filament. Since the ratio of reflection in the direction is large and the feedback ratio of the infrared light reflected by the infrared reflection film is low, the improvement rate of the lamp efficiency is only 4 to 5% at most, but in the case of a spherical (G-type) bulb, Since the feedback rate of infrared rays is improved, the improvement rate of lamp efficiency is 30 to 40%.
Also improve.

However, as can be understood from FIG.
When the value of D exceeds 0.12, the thickness of the bulb 2 becomes relatively large, so that the distance PR in FIG. 2 becomes large, and the deviation of reflected light becomes large, so that the feedback rate of infrared rays decreases. ,
For this reason, improvement in lamp efficiency cannot be expected, and the center of the filament is intensively heated, so that the life is shortened. On the other hand, when the value of t / D is less than 0.05 , the thickness of the valve 2 becomes too small, and the bulb 2 does not have heat, and the spherical shape (G
Failures such as rupture occur regardless of the type) valve and the cylindrical type (T type) valve. Therefore, it is preferable to satisfy the following condition: 0.05 ≦ t / D ≦ 0.12 (1)

The present invention is not limited to the above embodiment. That is, in the embodiment of FIG. 1, the case where the bulb 2 is spherical is described, but the bulb may be an elliptical sphere close to a sphere. When an elliptical bulb is used, the filament contained therein is arranged so that the coil axis is along the long axis of the ellipse, and this filament is located at the first and second focal points of the ellipse. In this case, the valve diameter D corresponds to the valve diameter at an intermediate point between the focal positions.

In the example shown in FIG.
Has been described as an example of a lamp in which the coil axis is arranged along the bulb axis, but the filament may be arranged in a posture intersecting at 90 degrees to the bulb axis.

Further, the present invention is not limited to a halogen bulb as a bulb to be used, and may be a general incandescent bulb. The sealing structure at the end is not limited to a crushed sealing type, but a stem sealing. You may.

[0030]

As described above in detail, according to the present invention, since the bulb shape is spherical or elliptical, when the infrared ray emitted from the filament accommodated in the bulb is reflected by the infrared reflection film, the center of the bulb will be detected. Or, it goes to the direction of the focal position, so that it returns to the filament without fail. In this case, since the thickness of the bulb is regulated, the influence of the refractive index due to the thickness of the bulb wall can be reduced, and the return rate to the filament can be improved . like this
By improving the return rate to the filament,
Pump efficiency can be improved. In addition, outside the valve
By regulating the ratio between the diameter and the valve thickness, reducing the thickness t
To prevent a decrease in mechanical strength of the valve.
Stopping can improve the life of the valve.
Wear.

[Brief description of the drawings]

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

FIGS. 2 (a) and 2 (b) are diagrams for explaining the state of reflection of infrared rays of the embodiment. FIG.

FIG. 3 is a view showing lamp efficiency and life characteristics of the embodiment.

[Explanation of symbols]

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

Claims (1)

(57) [Claims] (1)At least one end has a sealing part, mainly
Is formed into a spherical or spheroidal shape and has an average
Assuming that the outer diameter is D and the average thickness is t, 0.05 ≦ t / D ≦ 0.
A valve configured to satisfy 12; An infrared reflecting film formed on the bulb; A filament disposed within the valve; Internal lead wire electrically connected to both ends of the filament
When; While being electrically connected to the internal lead wire,
An external lead wire derived from the sealing portion;  An incandescent light bulb comprising: