JPH0320959A - Lighting device - Google Patents

Abstract

PURPOSE:To obtain the light with high color rendering property at a high color temperature by making the line connecting the bulb seal side end of the filament of a halogen lamp and the outer edge of an effective reflection section on the seal end side of a reflecting mirror 60 deg. or above against an optical axis, or providing a film absorbing or reflecting the visible light on the bulb top section, and making the line connecting the film periphery and the side end of the filament top section 60 deg. or above against the bulb axis. CONSTITUTION:When a halogen lamp 1 is fitted to the preset position of a reflecting mirror 10, the line connecting the bulb seal side end section of the filament 5 of the lamp 1 and the outer edge of the back opening section 13 of the reflecting mirror 10, i.e., the back side outer edge of the effective reflection section, is set to 60 deg. or above against the optical axis O2 (i.e., bulb axis O1). When the lamp 1 is lighted, the filament 5 emits light, light enters a light interference film 8, part of it is reflected, the filament 5 is re-heated by the reflected light, and the luminous efficiency is improved with little power consumption. Since the back opening 13 of the reflecting mirror 10 has a large area, the light with a low color temperature from the seal end 3 of a bulb 2 is not reflected to the front, the color temperature on the radiation face is increased, and the color irregularity is reduced.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention provides a halogen light bulb having a multilayer light interference film (interference filter) formed on the surface of the bulb to increase the color temperature; The present invention relates to a lighting device including a reflecting mirror that reflects light emitted from the halogen light bulb.

(Prior Art) A spot downlight used, for example, in a store or the like is composed of a lamp as a light source and a reflecting mirror that houses the lamp and reflects the light emitted from the lamp.

Spot downlights like this should preferably have cool color light with high color rendering properties to enhance the lighting effect for product display.
For this reason, a lighting device that emits light with a high color temperature is desirable.

Conventionally, when trying to obtain light with such high color temperature and high color rendering properties, an incandescent light bulb was used as the lamp, and a reflector consisting of a dichroic mirror or cool mirror with a multilayer optical interference film formed on the opposite side was used. This uses approximately 600 to 700 of the light emitted from an incandescent bulb.
The red light in the nm range is absorbed or transmitted by the multilayer optical interference film, and the remaining light is reflected to the front, for example, 30 nm.
Light with a high color temperature of about 50 to 3,600K and high color rendering properties is emitted.

However, when conventional dichroic mirrors or cool mirrors are used, part of the light emitted from the lamp is absorbed or transmitted by the multilayer light interference film, so not all of the emitted light is used effectively, and the irradiated surface is There is a problem that the brightness of the light becomes low, that is, the luminous flux is greatly reduced, and the irradiation efficiency is reduced.

Therefore, it has been proposed to use a highly efficient halogen bulb as an incandescent bulb and to form a multilayer optical interference film on the inner or outer surface of the bulb.

This multilayer optical interference film is a film that transmits visible light and reflects infrared rays.It allows visible light emitted from the filament housed in the bulb to pass through, but it reflects infrared rays and returns them to the filament. The lamp efficiency was improved by heating the filament using the infrared rays generated by this anti-moon radiation.

Optical interference films with such functions are made of titanium oxide (T i O 2 ), which is a metal oxide with a high refractive index and has excellent optical properties such as transmittance and refractive index, as well as excellent heat resistance.
Silicon oxide (SiOz), which has excellent optical properties and heat resistance, is used as a metal oxide with a low refractive index.

In particular, recently, some lamps have been developed that cut the transmission of light in this region by reflecting red light in the approximately 600 to 700 nm region and return it to the filament, and as a result, emit light with a high color temperature of approximately 3800 K. It is being considered.

(Problem to be Solved by the Invention) However, not all of the light reflected by the above-mentioned optical interference film returns to the filament, and the light returned to the filament is absorbed by emissivity ε, and the remaining ( 1-ε
) is again radiated towards the valve. This phenomenon occurs repeatedly while the lamp is on.

By the way, in a halogen light bulb whose bulb shape is cylindrical, the filament is also cylindrical, and the filament axis is arranged so as to substantially coincide with the bulb axis. In such cylindrical halogen bulbs, compared to spherical bulbs, the incident angle of the light emitted from the filament to the multilayer optical interference film differs depending on the location, and the transmission characteristics of the multilayer optical interference film have angular dissimilarity. Therefore, the energy distribution of emitted light varies depending on the location of the lamp.

When such a cylindrical halogen light bulb is housed in a reflector and arranged so that the bulb axis approximately coincides with the optical axis, the energy distribution of the emitted light will differ depending on the location of the lamp, as described above. From, the light reflected by this mirror,
In other words, the irradiated light on the irradiated surface has color irregularities in places, and the problem occurs that a desired color temperature cannot be obtained.

The present invention aims to provide a lighting device that can prevent color unevenness in irradiated light from occurring depending on the location and that can provide a high color temperature.

[Structure of the Invention] (Means for Solving the Problems) The first aspect of the present invention is to house a filament in a cylindrical bulb so that the filament axis substantially coincides with the bulb axis, and to adjust the color temperature on the outer surface of the bulb. It consists of a halogen bulb on which a multilayer light interference film is formed to raise the light, and a reflecting mirror that accommodates the halogen bulb so that the bulb axis is approximately located on the optical axis and reflects the light emitted from the halogen bulb. In the lighting device, a line connecting the end of the filament on the bulb sealing side and the outer edge of the effective reflecting part at the end of the sealing side of the reflecting mirror is at an angle of 60° with respect to the optical axis.
It is characterized by forming an angle greater than or equal to the above.

The second aspect of the present invention is that a light-shielding film that absorbs or reflects visible light is formed on the top of the bulb, and a line connecting the periphery of the light-shielding film and the top end of the filament is aligned with the bulb axis. It is characterized by forming an angle of 606 or more.

(Function) According to the first aspect of the present invention, light with a low color temperature emitted from the sealed end side of a halogen light bulb is cut off by the ineffective reflecting portion on the back side of the reflecting mirror and is no longer reflected, so that it is not irradiated. Since the surface is no longer irradiated with light with a low color temperature, a high color temperature can be obtained and color unevenness can be prevented from occurring.

According to the second aspect of the present invention, the light with a low color temperature emitted from the top side of the bulb is blocked by the light shielding film, so that the irradiation surface is not irradiated with light with a low color temperature, and a high color temperature is obtained. The occurrence of color unevenness is reduced.

(Example) The present invention will be described below based on an example shown in the drawings.

In the figure, 1 indicates a halogen bulb, and 10 indicates a reflecting mirror.

The halogen light bulb 1 has a cylindrical (straight tube) bulb 2 made of transparent quartz glass and has an outer diameter of 10+ am, for example, and a crush sealing portion 3 is formed at one end of the bulb 2. A pair of metal foil conductors (well-known or not shown) made of molybdenum or the like are sealed in this sealing portion 3, and internal lead-in wires 4, 4 are connected to these metal foil conductors. These internal lead-in lines 4, 4 are led into the valve 2,
A filament 5 made of tungsten is connected between these ends.
has been erected. The filament 5 is formed of a coil, and the coil axis is positioned above the valve axis 01.

A cap 6 is attached to the crush sealing portion 3, and the metal foil conductors 3, 3 are connected to the cap 6 via an external lead-in wire (not shown).

The valve 2 is filled with argon gas and halogen at a predetermined pressure.

A multilayer optical interference film 8 is formed on the outer surface of such a bulb 2, and this optical interference film 8 is an interference film for improving color temperature, and as shown in FIG. 2, it has a high refractive index. The layers 81 and the low refractive index layers 82 are alternately laminated to form a multilayer film of, for example, 9 to 12 layers in total.

The high refractive index layer 81 is made of titanium oxide (T iO 2 ),
Tantalum oxide (TA205) Zirconium oxide (Z
rO2) Made of zinc sulfide (ZnS), etc., and low refractive index WI82 is made of silicon oxide (silica SiO)
, magnesium fluoride (MgFz), etc.

In this embodiment, the multilayer optical interference film 8 has odd-numbered layers as high refractive index layers 81 with a refractive index of 2.0 or more, and even-numbered layers as low refractive index layers 82 with a refractive index of 1.6 or less. ing. The optical film thickness (one refractive index x film thickness) d of each layer from the bulb 2 side to the m-th odd layer is 0.12 to 0.17 μm.
It is formed of a multilayer film including a high refractive index layer 81 and a low refractive index layer 82. Then, the optical film thickness on the outside is (
1+k)/2Xd, (k is a constant from 1.2 to 1.5)
A high refractive index layer 81 and a low refractive index layer 82 are formed by stacking a low refractive index layer 82, and each layer has an odd number of layers having an optical thickness d2 of kdt (-0.144 to 0.255) on the outside thereof.
A multilayer film is provided, and the outermost layer has an optical thickness of d2/2.
A low refractive index layer 82 is formed. In this case, the number of multilayer films having the optical thickness d2 is one or more and is in the range of m-4 layers.

In the halogen light bulb 1 incorporating such a multilayer light interference film 8, when the light bulb is turned on and the spectral distribution is measured with a spectroradiometer at the center of the filament in a direction perpendicular to the bulb axis, the spectral distribution is as shown in FIG. Approximately 600 to 700 r
The red region of v was cut out, and the color temperature was measured and found to be 3850K.

On the other hand, a clear type halogen light bulb that does not have the multilayer light interference film 8 has a color temperature of 2850K, and therefore a halogen light bulb that has the multilayer light interference film 8 with the above structure has a color temperature that is significantly improved. I understand.

A light shielding film 9 is formed on the top of the bulb 2 to absorb or reflect visible light. This light shielding III 9 is
For example, cobalt oxide (CoO), nickel oxide (Ni
Visible light absorbing film consisting of a black film such as O),
Or titanium oxide (TLO2), aluminum oxide (
It is composed of a reflective film made of a fine particle coating such as At20, ).

This light-shielding film 9 covers the top of the bulb 2, and the angle α between the line connecting the periphery of this light-shielding film 9 and the top end of the filament 5 and the bulb axis 01 is 60″ or more. It is formed in an area that looks like this.

The halogen light bulb 1 having such a configuration is housed in the reflecting mirror 10.

The reflecting mirror 10 is made of aluminum, for example, and has a reflecting surface 11 in the form of a paraboloid of revolution. This reflection mlo has openings 12 and 13 on the front and back sides, respectively. The front opening 12 is a light emitting port and has an inner diameter of, for example, 60a+s, and the back opening 13 is a lamp insertion tube. The inner diameter is, for example, 22tsm. The distance of the effective reflecting portion from the front opening 12 to the rear opening 13 is, for example, 25 ffim.

This anti-1.1 mirror 10 is housed in a housing 15 that forms the main body of the illumination device. The housing 15 has a partition wall 1
6 is provided, and the above-mentioned reflecting mirror 1 is provided on this partition wall l6.
0 is fixed, which causes the reflection vt10
The front opening 12 is a light emitting port 1 formed in the housing 15.
8 and is fixed to this light projection port 18.

The housing 15 has a back chamber 1 divided by a partition wall 16.
A socket 20 is provided in the socket 20.
The cap 6 of the halogen light bulb 1 is attached to the holder. Therefore, the halogen light bulb 1 is attached to a predetermined position on the reflecting mirror 10.

In this case, the bulb axis O, of the halogen bulb 1 has a reflection mI
It is attached so as to substantially coincide with the central axis of O, that is, the optical axis 02.

In this way, the halogen bulb 1 is placed at a predetermined position on the reflector 10.
When the halogen bulb 1 is turned on, the light emitted from the halogen bulb 1 is reflected by the reflective surface 11 of the reflector 10.
, and is projected forward from the front opening 12 .

When the halogen bulb 1 is attached to a predetermined position on the reflector 10, the end of the bulb sealing side of the filament 5 of the halogen bulb 1 and the outer edge of the back opening 13 of the reflector 10, that is, the effective reflecting part. The line connecting the outer edge of the back side is
Angle β with respect to the above optical axis 02 (-bulb axis 0,)
is set to be 60″ or more.

The operation of such a lighting device will be explained.

When the halogen bulb 1 is turned on, the filament 5 emits light, and this light passes through the bulb 2 and enters the light interference film 8.

A part of this incident light is reflected by optical interference pA8,
This reflected light is returned to the filament 5. Therefore, the filament 6 is heated again by the reflected light, so power consumption is reduced and luminous efficiency is improved.

Further, the remaining light passes through this optical interference film 8 and is emitted to the outside.

In particular, in the optical interference film 8 of this embodiment, the odd-numbered layers have a refractive index of 2.0.
The above-described high refractive index layer 81 has an even-numbered layer that is a low refractive index layer 82 with a refractive index of 1.6 or less, and the optical film thickness of the multilayers from the bulb 2 side to the mth (m is an odd number) ( It is formed of a multilayer film in which high refractive index layers 81 and low refractive index layers 82 with dr (refractive index x film thickness) dr of 0, 12 to 0.17 JllI1 are laminated alternately, and the optical film thickness on the outside is (1+k )/2X
A low refractive index layer 82 of d+ (where k is a constant of 1.2 to 1.5) is laminated, and multiple layers are formed on the outside of this layer, so that the optical thickness d2 of each layer is kd, (-0.144 to 0. 255) is provided, and the outermost layer forms a low refractive index layer 82 with an optical thickness of d2/2, and the multilayer film with the optical thickness of d2 is one or more layers. Since the number is in the range of m-4 layers, it gently cuts light from around 450 nI1 and above, and reflects light centered on the red region of 600 to 700 nI, thus 3850 nI.
A clear type color temperature of 2850 is obtained.
The color temperature is much higher than K.

By the way, when a halogen light bulb 1 having such a light interference film 8 but not having a light shielding film 9 is attached to a conventional reflector having a small diameter back opening 13 and turned on, the irradiation is The color temperature at the center of the surface is 3200K, which is lower than the color temperature 3850K in the direction perpendicular to the bulb, and the color tone is closer to greenish.
Furthermore, it was observed that ring-shaped striped color unevenness occurred.

When we investigated the cause of this, we found the following reasons.

That is, the light emitted from the filament 5 is transmitted to the bulb 2.
The light interference film 8 transmits the unnecessary area, especially 600 to 70
The 0 nm red region is reflected back to the filament 5. This reflected light is absorbed by the filament 5 by an amount corresponding to its absorption rate ε, and the rest is radiated from the filament 5 again. The absorption coefficient ε of the filament 5 is about 0.3 to 0.45, and more than 50% of the reflected light is emitted from the filament 5 again. A portion of the re-radiated light repeats the above-mentioned reflection and radiation.

Here, the optical interference film has a property that its transmission characteristics depend on the angle of incidence, and as the angle of incidence increases, its transmission characteristics shift toward shorter wavelengths. In other words, the light emitted from the center of the filament 5 in a direction perpendicular to the bulb axis 01 has the above-mentioned infrared region of about 600 to 700 nm well cut out, and has a strong blue tinge, so it exhibits a high color temperature of 3850K. As for the light emitted from the bulb axis 01 in an oblique direction, the larger the inclination angle, the lower the cut effect in the infrared region of 600 to 700 nm, which makes the reddish light stronger and the color temperature lowered. do.

For this reason, in the cylindrical bulb 2, the color temperature increases as it approaches the center of the filament 5, and the color temperature decreases as it moves away from the filament 5, that is, closer to the sealed end 3 and the bulb neck.

When such a halogen light bulb 1 is housed in a conventional reflector, the reflector directly reflects the high color temperature area and the low color temperature area, which causes the irradiation to be interrupted as described above. The color temperature in the center of the surface is 320
The color becomes low to 0K, the color tone becomes close to greenish, and ring-shaped striped color unevenness occurs.

An object of the present invention is to prevent the color temperature from decreasing as described above and to prevent the occurrence of color unevenness.

Therefore, when the halogen bulb 1 is attached to a predetermined position on the reflector 10, the bulb sealing side end of the filament 5 of the halogen bulb 1 and the back opening 13 of the reflector 10 are connected to each other.
The line connecting the outer edge of the effective reflection section, that is, the outer edge of the effective reflection section on the back side, is set so that the angle β formed with the optical axis 02 (-bulb axis 0+) is 60'' or more.

According to such a configuration, light with a low color temperature emitted from the sealed end 3 side of the bulb 2 is directed forward because the opening area of the rear opening 13 of the reflecting mirror 10 is large, that is, no reflection occurs. will no longer be reflected. In other words, the reflecting mirror 10 does not reflect light with a low color temperature emitted from the sealed end 3 side of the bulb 2. Therefore, since light with a low color temperature does not reach the irradiated surface, the temperature of the irradiated area becomes high, and color unevenness is reduced.

On the other hand, since it has the effect of absorbing or reflecting visible light, it blocks light with a low color temperature that is about to be emitted from the top side of the bulb 2. Therefore, the light with a low color temperature emitted from the second section of the bulb does not reach the irradiation surface, and in this case as well, the color temperature of the irradiation surface becomes high and color unevenness is reduced.

Therefore, the end of the filament 5 of the halogen light bulb 1 on the bulb sealing side and the above-mentioned opposite! 11 A line connecting the outer edge of the back opening 13 of the mirror 10 is the optical axis 02 (-bulb axis 0+
) is set to be 60 degrees or more, and the line connecting the periphery of the light-shielding film 9 formed on the top of the bulb 2 and the top end of the filament 5 is the same as the above-mentioned bulb axis. The reason for setting the angle α with 01 to be 60′ or more is based on experiments conducted by the present inventors, and the results of the experiments are shown in the table below.

The angle α-60'' in Example 5 is for the case where the light-shielding film 9 is formed of a visible light-absorbing film made of a black coating, whereas the angle α-60'' in Example 6 is This is a case where the film 9 is constituted by a reflective film made of a fine particle film.

As can be understood from the table above, in order to maintain a high color temperature at the center of the irradiated surface, it is desirable to set the angle β to 60" or more, and if it is 60" or more, the color temperature is 380.
0K is obtained.

Further, if the angle α is set to 60@ or more, the color temperature can be further increased.

It should be noted that the present invention is not limited to the configuration of the above-described embodiments, and is not limited to the structure of the optical interference film, for example, as long as the optical interference film is formed to increase the color temperature.

In addition, the structure of the reflective mIO is not limited to aluminum,
It may be made of glass.

Furthermore, the effective reflecting part is defined as the part excluding the ineffective part of the light reflection 14, such as the part excluding the rear opening shown in the example, or the part formed with a substantially flat surface that does not normally reflect on the back part. refers to an area.

Furthermore, the present invention is not limited to spot downlights;
Any illumination device that uses a combination of a halogen bulb and a reflecting mirror can be applied, and it may also be an integrated device in which a halogen bulb and a reflecting mirror are formed into a double tube structure.

[Effects of the Invention] As explained above, according to the first aspect of the present invention, light with a low color temperature emitted from the sealed end side of the halogen bulb is no longer reflected on the back side of the reflecting mirror, so that the irradiated surface Since light with a low color temperature is no longer irradiated on the screen, a high color temperature can be obtained and the occurrence of color unevenness can be reduced.

According to the second aspect of the present invention, the light with a low color temperature emitted from the top side of the bulb is blocked by the light shielding film, so that an even higher color temperature can be obtained and the occurrence of color unevenness can be prevented.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a sectional view of a lighting device, FIG. 2 is a sectional view showing the structure of a light interference film on a bulb wall, and FIG. 3 is a characteristic diagram showing transmittance. be. DESCRIPTION OF SYMBOLS 1... Halogen light bulb, 2... Bulb, 5... Filament, 8... Optical interference film, 81... High refractive index layer,
82... Low refractive index layer, 9... Light shielding film, 10... Reflecting mirror, 11... Reflecting surface, 12... Front opening, 13
...Back opening. Figure 3

Claims (2)

[Claims] (1) A halogen light bulb in which a cylindrical bulb accommodates a filament so that the filament axis substantially coincides with the bulb axis, and a multilayer light interference film is formed on the outer surface of the bulb to increase the color temperature, and this halogen bulb A lighting device comprising: a reflecting mirror that accommodates the bulb so that the bulb axis is approximately located on the optical axis, and reflects light emitted from the halogen bulb; an end of the filament on the bulb sealing side; A lighting device characterized in that a line connecting the outer edges of the effective reflecting portions at the sealed end of the lighting device forms an angle of 60° or more with respect to the optical axis. (2) A light-shielding film that absorbs or reflects visible light is formed on the top of the bulb, and a line connecting the periphery of this light-shielding film and the top end of the filament is at an angle of 60° to the bulb axis.
The lighting device according to claim 1, characterized in that the lighting device forms an angle greater than or equal to the above angle.