JPH10214597A - Low-pressure mercury vapor discharge lamp, lighting device and display device - Google Patents

Abstract

(57) [Problem] To provide a low-pressure mercury vapor discharge lamp that prevents a decrease in efficiency in a low power range and a low temperature environment, and prevents light output saturation in a high power range. A low-pressure mercury vapor discharge lamp (1) includes an arc tube (2).
Has a three-wavelength type phosphor layer 3 on the inner surface side, and an outer tube 4 is formed coaxially. A gap 6 filled with mercury is formed between the arc tube 2 and the outer tube 4. Nickel cylindrical cold cathodes 9 each having an integral sealing portion 7 formed at both ends of the arc tube 2 and the outer tube 4 and connected to a dumet wire 8 as one wire, respectively.
Is provided. When the temperature is low, the vapor pressure of the gap 6 is low and the heat insulation is high. At the time of high temperature, the vapor pressure of the gap 6 is suppressed. This prevents the heat insulation from becoming excessive and increasing the temperature to saturate the light output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-pressure mercury vapor discharge lamp, a lighting device and a display device.

[0002]

2. Description of the Related Art Conventionally, as a low-pressure mercury vapor discharge lamp using a double tube, for example, the configuration described in Japanese Utility Model Laid-Open No. 2-70355 is known.

In Japanese Utility Model Laid-Open Publication No. 2-70355, an outer tube surrounding the inner tube is provided coaxially with a longitudinal cylindrical inner tube via a vacuum gap, and the inner tube is insulated from outside air while being insulated. Describes a low-pressure mercury vapor discharge lamp capable of suppressing a decrease in luminous efficiency even in a low-temperature atmosphere, even if the power consumption is small and the heat capacity is small, in which the contact is prevented.

[0004]

However, when the low-pressure mercury vapor discharge lamp is used in a large power region with a vacuum in the gap in the configuration described in Japanese Utility Model Application Laid-Open No. 2-70355, the temperature rises due to heat insulation. When the light output is saturated or reduced, and when the gap is set to the atmospheric pressure, the heat insulation effect is reduced and the low temperature characteristic is deteriorated particularly in a low power region.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a low-pressure mercury vapor discharge lamp which prevents a decrease in efficiency in a low power range and a low temperature environment and prevents light output saturation in a high power range. An object is to provide a lighting device and a display device.

[0006]

According to a first aspect of the present invention, there is provided a low-pressure mercury vapor discharge lamp in which a discharge medium mainly composed of mercury is sealed and a pair of electrodes are sealed at both ends; An outer tube that surrounds the gap through which a substance that changes the pressure by the change is enclosed.The pressure of the substance changes due to a temperature change. In addition to preventing a decrease in efficiency due to lack of heat insulation in a low-temperature environment and a low-temperature environment, it also prevents excessive heat insulation in a large power range from causing temperature rise and saturation of light output.

The low-pressure mercury vapor discharge lamp according to the second aspect is the low-pressure mercury vapor discharge lamp according to the first aspect,
Since the tube outer diameter is 8 mm or less, it is possible to cope with a small size and a thin shape.

The low-pressure mercury vapor discharge lamp according to claim 3 is the low-pressure mercury vapor discharge lamp according to claim 1 or 2, wherein the gap is 1 mm or less, and the vapor pressure of the substance is 1 mm or less.
It varies within the range of 0 ^-3 Pa to 1000 Pa. Since the gap is 1 mm or less, light loss to, for example, a lighting device can be minimized, and the vapor pressure of the material in the gap is 10 ^-3 Pa to 1000 Pa. In order to prevent the decrease in efficiency due to lack of heat insulation in low power range and low temperature environment, heat insulation is appropriately performed in low power range and low temperature environment. To prevent the light output from saturating due to the temperature rise.

A low-pressure mercury vapor discharge lamp according to claim 4 is the low-pressure mercury vapor discharge lamp according to any one of claims 1 to 3, wherein the substance mainly contains at least one of mercury and a mercury compound. Sometimes, the vapor pressure is reduced to enhance the heat insulating effect, and at high temperatures, the vapor pressure is increased to prevent excessive heat insulation.

A low-pressure mercury vapor discharge lamp according to claim 5 is the low-pressure mercury vapor discharge lamp according to any one of claims 1 to 3, wherein the substance is mainly iodine, bromine,
Contains at least one of water, iodine compounds, bromine compounds and mercury compounds. At low temperatures, the vapor pressure decreases to increase the heat insulation effect, and at high temperatures, the vapor pressure increases to prevent excessive heat insulation. .

According to a sixth aspect of the present invention, there is provided an illuminating apparatus comprising the low-pressure mercury vapor discharge lamp according to any one of the first to fifth aspects and a fixture body to which the low-pressure mercury vapor discharge lamp is attached. To play.

According to a seventh aspect of the present invention, there is provided a display device including the illumination device according to the sixth aspect, and display means for irradiating the illumination device, and has respective functions.

In any case, the inner tube includes a tube on which a phosphor layer is formed.

Although the outer tube can be applied when the outer tube is 8 mm or less, it is preferably 4 mm or less in consideration of the tendency of miniaturization of equipment to be mounted, and the size of 4 mm or less can be sufficiently realized. is there.

Further, the term "mainly used" means that the gas present in the gas in the gap generally exceeds 50% in partial pressure ratio.

Further, the inner tube and the outer tube are formed of any material such as soda lime glass, lead glass or hard glass, and are preferably of the same quality.
There is no problem with different materials.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid crystal display according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing a low-pressure mercury vapor discharge lamp, and FIG. 2 is a longitudinal cross-sectional view showing a low-pressure mercury vapor discharge lamp.
It does not show the dimensions exactly. The low-pressure mercury vapor discharge lamp 1 has an arc tube 2 as a straight inner tube made of glass such as soda lime glass, lead glass, or hard glass. A body layer 3 is formed, and an outer tube 4 made of glass similar to the arc tube 2 is formed coaxially with the arc tube 2.
A discharge path 5 is formed therein, and a gap 6 in which mercury (Hg) is sealed is formed between the arc tube 2 and the outer tube 4.
At both ends of the arc tube 2 and the outer tube 4, an integral sealing portion 7 is formed. A pair of nickel (Ni) cylindrical field emission devices connected to dumet wires 8, 8 as one wire are respectively provided on the sealing portions 7, 7 at both ends of the arc tube 2 and the outer tube 4. Are provided as cold cathodes 9, 9 as electrodes.

The substance sealed in the gap 6 includes:
Not only mercury or a mercury compound but also a vapor pressure change of 100 times or more is sufficient. For example, a substance such as iodine (B), a mercury compound or an iodine compound, whose vapor pressure increases with an increase in temperature is used. Can obtain the same effect.

The low-pressure mercury vapor discharge lamp 1 has a total length of 200 mm, the arc tube 2 has an outer diameter of 2.4 mm, and the outer tube 4 has a diameter of 2.4 mm.
The outer diameter of the tube is 3.6 mm, and the thickness of the arc tube 2 and the outer tube 4 is 0.3 mm.
Rare gas such as neon (Ne) gas is 1 × 10 ⁴ Pa and mercury vapor is sealed in the arc tube 2 at 3 mm. Further, the length of the dumet wire 8 in the sealing portion 7 is 2 m.
m, the heat generated by the cold cathode 9 is prevented from being conducted to the periphery of the cathode to form a coldest part, thereby preventing a decrease in efficiency. The same effect can be obtained if the length of the dumet wire 8 in the sealing portion 7 is 5 mm or less.

The arc tube 2 and the outer tube 4 in the gap 6
Is 0.2 mm in the radial direction, and the pressure or degree of vacuum of the mercury vapor sealed in the gap 6 (hereinafter referred to as “pressure”).
Is 10 ⁻³ Pa at a temperature of −20 ° C., 10 ⁻¹ Pa at a temperature of 20 ° C.,
At 80 ° C., the pressure changes to 10 Pa or 10,000 times or more.
The distance in the radial direction of the gap 6 is set to 0.2 mm. However, if the distance is about 1 mm or less, there is no problem. If the distance exceeds 1 mm, not only the diameter of the low-pressure mercury vapor discharge lamp 1 increases, but also the low-pressure When the mercury vapor discharge lamp 1 is mounted on a lighting device or the like, the distance between the arc tube 2 and the light incident target is 1 mm or more, which causes a problem that the spectral loss increases.

When the low-pressure mercury vapor discharge lamp 1 is formed, first, a discharge medium mainly composed of mercury (Hg) is sealed in the arc tube 2, and a Dumet wire 8 is attached to both ends and sealed. . Next, one end of the arc tube 2 is connected to the outer tube 4.
Then, the arc tube 2 and the outer tube 4 are melted by a gas burner and the portion of the dumet wire 8 is sealed. Further, while being evacuated in a vacuum system, the gas is heated to a high temperature, for example, 400 ° C. or higher, to exhaust the impurity gas inside the gap 6, and a high vacuum state of 10 ⁻⁵ Pa is filled to fill in mercury. Finally, the end of the discharge tube 2 on the exhaust side is heated from above the outer tube 4 to seal the discharge tube 2 and the outer tube 4 mainly on the Dumet wire 8, thereby completing the low-pressure mercury vapor discharge lamp 1. .

The cold cathodes 9 and 9 have an output voltage waveform having a pulse-like frequency of 40 kHz or more and a voltage of 400 to 5
A lighting circuit (not shown) is connected which has a voltage of about 00 V, a lamp current of about 5 mA or less, and a lamp input power of about 2 W.

FIG. 3 is a cross-sectional view showing a liquid crystal display device. Reference numeral 11 denotes a liquid crystal display device. The liquid crystal display device 11 has a thin box-shaped case body 13 having a front opening 12 for irradiation. A backlight unit 14 serving as a lighting device is housed in the case body 13. This backlight unit 14
Has a low-pressure mercury vapor discharge lamp 1, and a silver-deposited film serving as a proximity conductor near the low-pressure mercury vapor discharge lamp 1 so as to include the outer tube 4 of the low-pressure mercury vapor discharge lamp 1. The reflecting mirror 15 is wound in an open state in one direction, and a light guide plate 16 made of an acrylic resin is disposed in the irradiation direction of the reflecting mirror 15.
Are located opposite to each other. A flat reflecting plate 18 is provided on the back side of the light guide plate 16, and a control panel constituted by a diffusion plate 20 and a light collector 21 is provided between the light guide plate 16 and the opening 12 of the case body 13. Light means 22 is provided. And the case body 13
A liquid crystal display unit 24 as a display means is disposed on the front side of the opening 12.

Next, the operation of the above embodiment will be described.

First, a voltage is applied between the cold cathodes 9, 9 by a lighting circuit to start and light up. And the cold cathodes 9, 9
The mercury vapor is excited by the discharge between
UV light is excited, and the three-wavelength phosphor emits light.
The light is reflected in the direction of the light guide plate 16 by the light guide 15, the light is guided by the light guide plate 16, and the liquid crystal display unit 24 is illuminated from the back through the diffusion plate 20 and the light collector 21 to display.

At a low temperature of -20.degree. C., the vapor pressure of the gap 6 is ^10.sup.-3 Pa and the heat insulating property is high. At a normal temperature of 20.degree. C., the vapor pressure of the gap 6 is ^{10.sup.- 1} Pa and the heat insulating property is slightly lowered. At a high temperature of 80 ° C., the vapor pressure of the gap 6 rises to 10 Pa to suppress heat insulation, prevent a decrease in efficiency due to lack of heat insulation in a low power region and a low temperature environment, and insulate a large power region. Is excessive and the temperature rises to prevent the light output from being saturated. Note that the thermal conductivity of the gap 6 slightly changes strictly in proportion to the temperature, but the change in the degree of vacuum is about several tens of times, and the change in the thermal conductivity is small. .

That is, as shown in FIG. 4, the gap a filled with iodine a and the gap filled with mercury b
Is that the saturation of the luminance in the high power region is smaller than that of the vacuum c, and the lamp luminance can be increased, and the lamp luminance in the low power region is higher than that of the atmospheric pressure d. Can be kept.

Particularly, in the case of a lamp having a length of 200 mm, as shown in FIG. 5, the gap 6 has a vacuum (10 ^-1 Pa).
Is that the gap 6 is at atmospheric pressure and that e and nitrogen (N ₂ ) are 10
When the lamp power is lower than that of Pa, the lamp brightness becomes higher. However, as the lamp power increases, the lamp brightness becomes lower than that of the single tube e. However, the lamp a in which iodine was encapsulated had the same luminance as the lamp a in which iodine was encapsulated even when the lamp power was low. When the lamp power was increased, the luminance became equivalent to that of 10 Pa. Therefore, it is considered that the one a in which iodine is sealed, which has a higher lamp luminance than the case of a single tube as a whole, is preferable, and it is considered that these are because the iodine molecules themselves are sparse and do not easily conduct heat.

In relation to the ambient temperature, as shown in FIG. 6, the gap a filled with iodine a has a relatively lower relative lamp brightness than the vacuum d in the low temperature range. Both of the element a filled with elemental gas and the element b filled with mercury, the gap 6 has less saturation of luminance in a high temperature range and higher relative lamp luminance than the liquid crystal c with a gap 6,
The relative lamp brightness in the low temperature region can be increased as compared with the case where the gap 6 has the atmospheric pressure.

In particular, as shown in FIG. 7, in the lamp having a lamp length of 200 mm, the lamp a having iodine enclosed in the gap has a lower brightness when the ambient temperature exceeds 30 ° C. as compared with the lamp e having a single tube. However, the brightness is sufficiently high from a low temperature range to about 25 ° C.

The thermal conductivity is proportional to the distance of the gap 6, and is not directly related to the internal pressure. However, when the mean free path of the gas inside is larger than the gap 6, the free molecular heat conduction becomes dependent on the vapor pressure. In order to obtain almost the same optical characteristics as a low-pressure vapor discharge lamp that is not a double tube in accordance with the reduction in the thickness of the apparatus, the gap 6 must be 1 m.
m or less, and most atoms and molecules have an average free path longer than the interval of the gap 6 due to a decrease in vapor pressure, and the thermal conductivity changes due to a change in vapor pressure. Therefore, when the gap 6 is reduced, a change in the vapor pressure affects the lamp brightness.

Next, a method of manufacturing another low-pressure mercury vapor discharge lamp 1 will be described with reference to FIG.

FIG. 8 is a partially cutaway side view showing a manufacturing process of a low-pressure mercury vapor discharge lamp according to another embodiment. As shown in FIG. Arc tube 2 concentric with standard part, smaller in diameter than standard thickness part
A small diameter portion 4a slightly wider than the outer circumference of the arc tube is formed, and the outer diameter of the arc tube 2 is positioned in the small diameter portion 4a.

Then, the small diameter portion 4a is welded and sealed to the outer periphery of the arc tube 2 and exhausted from the open side A of the outer tube 4, and the outer tube 4 corresponding to the other end of the arc tube 2 emits light. The gap 6 is sealed by being welded to the tube 2, and the entire side of the arc tube 2 is prevented from coming into contact with the outer tube 4 to prevent the gap 6 from shifting, so that the cross-section is annular. A low-pressure mercury vapor discharge lamp 1 having a uniform gap 6 is formed.

A method for manufacturing a low-pressure mercury vapor discharge lamp according to another embodiment will be described with reference to FIG.

FIG. 9 is a partially cutaway side view showing a manufacturing process of a low-pressure mercury vapor discharge lamp according to another embodiment. The embodiment shown in FIG. 9 differs from the embodiment shown in FIG. Instead of the small-diameter portion 4a, the end of the arc tube 2 is substantially concentric.
In this case, the gussing portion 4b is formed slightly narrower than the outer periphery of the squeezed portion. Then, the gluing portion 4b is welded to the outer periphery of the arc tube 2 to form the same as in FIG.

Further, a method of manufacturing a low-pressure mercury vapor discharge lamp according to another embodiment will be described with reference to FIG.

FIG. 10 is a partially cutaway side view showing a manufacturing process of a low-pressure mercury vapor discharge lamp according to another embodiment.
In the embodiment shown in FIG. 10, the protrusions 4c and 4d whose inner diameters are slightly larger than the outer diameter of the arc tube 2 are directed inward near one end of the outer tube 4 and near the other end of the arc tube 2. The protrusion is formed in such a manner that the arc tube 2 is positioned in the protrusions 4c and 4d, and one end side of the arc tube 2 of the outer tube 4 is welded to form the same as in FIG.

Further, a method of manufacturing a low-pressure mercury vapor discharge lamp according to another embodiment will be described with reference to FIG.

FIG. 11 is a partially cutaway side view showing a manufacturing process of a low-pressure mercury vapor discharge lamp according to another embodiment.
The embodiment shown in FIG. 11 differs from the embodiment shown in FIG. 10 in that only the protruding portion 4c is formed on one end side. In this manner, even if the protrusion 4c is formed only on one end side, the alignment can be performed, and the entire side of the arc tube 2 is prevented from contacting the outer tube 4. Even if it does not become, even if it becomes the maximum diagonal, it is the state shown in FIG.
The entire side of the arc tube 2 does not contact the outer tube 4.

If a display panel such as a vehicle-mounted instrument is provided in place of the liquid crystal display unit of the above embodiment, a vehicle-mounted display device can be constructed.

The outer diameter of the arc tube 2 is not limited to 3.6 mm, but the same effect can be obtained if it is 8 mm or less, preferably 4 mm or less.

Further, since a film on which a metal film as a conductive member is deposited can be used for the reflecting mirror 15, the light use efficiency of the low-pressure mercury vapor discharge lamp 1 can be improved. Alternatively, various synthetic films and plastic members may be used.

The arc tube 2 and the outer tube 4 are preferably made of semi-hard glass having a coefficient of thermal expansion α of 50 or less.
Different materials may be used, for example, one may be soft glass and the other may be hard glass.

[0046]

According to the low pressure mercury vapor discharge lamp according to the first aspect of the present invention, the pressure of the substance changes due to the temperature change.
The insulation effect of the gap changes, preventing a decrease in efficiency due to lack of insulation in low power range and low temperature environment,
It is possible to prevent the light output from saturating due to excessive heat insulation and a temperature rise in a large power range, thereby improving luminance.

According to the low-pressure mercury vapor discharge lamp according to the second aspect, in addition to the low-pressure mercury vapor discharge lamp according to the first aspect, the outer diameter of the tube is 8 mm or less.

According to the low-pressure mercury vapor discharge lamp according to the third aspect, in addition to the low-pressure mercury vapor discharge lamp according to the first or second aspect, since the gap is 1 mm or less, light loss to, for example, a lighting device is minimized. Since the vapor pressure of the material in the gap changes within the range of 10 ^-3 Pa to 1000 Pa, the inner tube is appropriately kept warm by heat insulation by free molecular heat conduction, and lack of heat insulation in a low power region and a low temperature environment. In addition to preventing a decrease in efficiency due to, for example, the above, it is possible to prevent the heat insulation from becoming excessive due to excessive heat insulation in a large power range, thereby preventing the light output from being saturated and improving the temperature over a wide temperature range.

According to the low-pressure mercury vapor discharge lamp according to the fourth aspect, in addition to the low-pressure mercury vapor discharge lamp according to any one of the first to third aspects, the substance mainly contains at least one of mercury and a mercury compound. When the temperature is low, the vapor pressure is reduced to enhance the heat insulating effect, and when the temperature is high, the vapor pressure is prevented from increasing and the heat insulation is not excessive, and the luminance can be improved.

According to the low pressure mercury vapor discharge lamp according to claim 5, in addition to the low pressure mercury vapor discharge lamp according to any one of claims 1 to 3, the substance is mainly iodine, bromine,
It contains at least one of water, iodine compounds, bromine compounds and mercury compounds.At low temperatures, the vapor pressure decreases to increase the heat insulating effect, and at high temperatures, the vapor pressure increases to prevent excessive heat insulation. And brightness can be improved.

According to the illuminating device of the sixth aspect, there is provided an apparatus main body to which the low-pressure mercury vapor discharge lamp according to any one of the first to fifth aspects is attached, and the respective effects are exhibited.

According to the display device of the seventh aspect, since the display device of the sixth aspect is provided, the respective effects can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a low-pressure mercury vapor discharge lamp of the present invention.

FIG. 2 is a longitudinal sectional view showing the same low-pressure mercury vapor discharge lamp.

FIG. 3 is a cross-sectional view showing the liquid crystal display device.

FIG. 4 is a graph showing a relationship between lamp luminance and electric power.

FIG. 5 is a graph showing a relationship between lamp luminance and electric power.

FIG. 6 is a graph showing a relationship between relative luminance and ambient temperature.

FIG. 7 is a graph showing a relationship between relative luminance and ambient temperature.

FIG. 8 is a partially cut-away side view showing a manufacturing process of the low-pressure mercury vapor discharge lamp according to the other embodiment.

FIG. 9 is a partially cutaway side view showing a manufacturing process of the low-pressure mercury vapor discharge lamp according to another embodiment of the invention.

FIG. 10 is a partially cutaway side view showing a manufacturing process of a low-pressure mercury vapor discharge lamp according to still another embodiment of the present invention.

FIG. 11 is a partially cut-away side view showing a manufacturing process of a low-pressure mercury vapor discharge lamp according to still another embodiment of the present invention.

[Explanation of symbols]

 1 low-pressure mercury vapor discharge lamp 2 arc tube as inner tube 4 outer tube 6 gap 11 display device 14 backlight unit as lighting device 24 liquid crystal display unit as display means

Claims (7)

[Claims] 1. A discharge medium mainly composed of mercury is sealed,
A low pressure comprising: an inner tube having a pair of electrodes sealed at both ends; and an outer tube surrounding the inner tube via a gap in which a substance that changes pressure by temperature change is enclosed. Mercury vapor discharge lamp. 2. The low pressure mercury vapor discharge lamp according to claim 1, wherein the outer diameter of the tube is 8 mm or less. 3. The low-pressure mercury vapor discharge lamp according to claim 1, wherein the gap is 1 mm or less, and the vapor pressure of the substance varies within a range of 10 ⁻³ Pa to 1000 Pa. 4. The substance according to claim 1, wherein the substance mainly contains at least one of mercury and a mercury compound.
4. The low-pressure mercury vapor discharge lamp according to any one of claims 3 to 3. 5. The low-pressure mercury vapor discharge according to claim 1, wherein the substance mainly contains at least one of iodine, bromine, water, an iodine compound, a bromine compound and a mercury compound. lamp. 6. A lighting device comprising: the low-pressure mercury vapor discharge lamp according to claim 1; and a fixture main body to which the low-pressure mercury vapor discharge lamp is mounted. 7. A display device comprising: the lighting device according to claim 6; and display means for irradiating the lighting device.