JP3139032B2 - Low pressure discharge lamp - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-pressure discharge lamp such as a fluorescent lamp suitable for a liquid crystal display or a backlight of various meters.

[0002]

2. Description of the Related Art A liquid crystal display device irradiates a liquid crystal surface by irradiating light from the back of a transmissive liquid crystal panel.
As such a backlight, a hot-cathode or cold-cathode fluorescent lamp capable of irradiating a liquid crystal surface having a predetermined spread with uniform brightness as a whole is effective. That is, when fluorescent lamps of a hot cathode or a cold cathode are used, these fluorescent lamps have excellent luminous efficiency and generate less heat compared with incandescent lamps, generate less heat, have a long life, and have a long discharge path, so that the luminous area is large. There is an advantage that the light distribution is easily uniform, and the discharge path is easily formed into a bent shape, for example, a U-shape or a W-shape. This is advantageous for irradiating the display surface with uniform brightness.

Incidentally, a low-pressure mercury vapor discharge lamp represented by a fluorescent lamp generally has a low starting pressure due to the low vapor pressure of mercury when it is intended to be started in a low-temperature atmosphere. However, even during stable lighting, if the ambient temperature is low, the vapor pressure of the encapsulated luminescent metal or luminescent gas will be low, and the luminous efficiency will be reduced.

[0004] In order to eliminate such starting characteristics and light emission characteristics, means for heating the discharge lamp with a heater has been proposed. If the discharge lamp is heated by a heater, the starting characteristics and the light emission characteristics can be improved without being affected by the surrounding temperature.

As a heater, a so-called laminator heater in which both upper and lower surfaces of a sheet heating element are laminated with a heat-resistant insulating film is used. It is directly attached to the outer surface.

[0006]

However, in the conventional laminating heater, both the upper and lower surfaces of the sheet heating element are subjected to insulation treatment and reinforcement treatment by laminating them with heat-resistant insulating films. When attached to the outer surface, a heat-resistant insulating film is interposed between the sheet heating element and the valve, so the heat of the sheet heating element is hindered by the heat-resistant insulating film and is not easily transmitted to the valve. There is a defect that is not efficient.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a low-pressure discharge lamp in which the heating efficiency of a bulb by a heater is improved.

[0008]

According to a first aspect of the present invention, there is provided a low-pressure discharge lamp comprising: a bulb in which a discharge medium is sealed; and a metal sheet heating element formed on one surface of a heat-resistant insulating film. A planar heater disposed on one side of the film except for the illumination direction of the bulb so that the body comes into contact with the non-illumination direction of the bulb outer surface. Claim 2 is the low-pressure discharge lamp according to claim 1,
The planar heater is characterized in that it is bonded via an adhesive outside the valve.

[0009]

According to a first aspect of the present invention, there is provided the low-pressure discharge lamp, wherein the metal sheet heating element formed on one surface of the heat-resistant insulating film is provided on the outer surface of the bulb.
Since one side of the film to be in contact with the non-illuminated direction is disposed outside excluding the illumination direction of the valve, with easy to manufacture the plane heater, the heating efficiency of the valve can be improved further in the illumination direction Is light because there is no film
The output does not decrease. According to the low-pressure discharge lamp of the second aspect, in addition to the function of the first aspect, the adhesion of the planar heater becomes easy.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to one embodiment shown in FIGS. This embodiment shows an example in which the present invention is applied to a meter lighting device, and 1 is a scale plate. This graduation plate 1 is made of a light diffusing plate such as acrylic or the like, and has graduations 2 on its surface along the circumferential direction.
The scale 2 is indicated by a pointer (not shown).

The scale 1 is illuminated from the back by a light source device provided on the back. That is, 3 is a reflector having a horseshoe shape in plan view, and the reflector 3 is formed of metal or synthetic resin and has a substantially semicircular cross section. Therefore, the reflector 3 has a generally U-shaped gutter shape. In addition, this horseshoe shape has a shape along the scale 2 formed on the surface of the scale 1.

On the inner surface of the reflector 3, there is formed a reflecting surface 4 made of a white or metal vapor-deposited film. The reflector 3 houses a cold cathode fluorescent lamp 10 as a light source. The cold cathode fluorescent lamp 10 has a horseshoe-shaped (U
The valve 11 has a flat shape such as an elliptical cross section. The fluorescent lamp 10 will be described later.

When the cold cathode fluorescent lamp 10 accommodated in the reflector 3 is turned on, this light is directly or directly reflected on the reflecting surface 4.
And is directed toward the opening of the reflector 3. The opening of the reflector 3 is covered with a light diffusion plate 5 made of acrylic or the like. The light diffusing plate 5 also has a horseshoe-shaped plane. Light traveling toward the opening of the reflector 3 is diffused by the light diffusion plate 5 and illuminates the back surface of the scale plate 1. The back illuminating light diffuses and passes through the scale 1 to raise the display scale 2.

The cold cathode fluorescent lamp 10 will be described with reference to FIG. The cold cathode fluorescent lamp 10 includes the U-shaped bulb 11 as described above, and the bulb 11 has a flat cross section. Cold cathodes 12, 12 are sealed at both ends of the bulb 11, and external lead wires 13, 13 connected to the cold cathodes 12, 12 are led out from the end face of the bulb 11. Valve 11
A phosphor film 14 is formed on the entire surface of the substrate.

A predetermined amount of mercury as a discharge medium and a rare gas such as argon or xenon are sealed inside the bulb 11. A planar heater 15 is attached to the lower surface of the valve 11. Planar heater 15
Has a horseshoe shape (U-shape) along the shape of the valve 11. The planar heater 15 of this embodiment has a single-sided structure.
For example, the sheet heating element 16 made of a metal mesh such as SUS is formed on one surface of a heat-resistant insulating film 17 such as a polyester resin sheet. Since the heat-resistant insulating film 17 also has a function of insulating and protecting the planar heating element 16, the heat-resistant insulating film 17 is formed to have a width larger than the outline of the planar heating element 16.

Such a planar heater includes a planar heating element 16.
One side is the lower surface of the valve 11 , that is, the non-light of the outer surface of the valve.
It is attached to the valve 11 so as to be in close contact in the bright direction . In this case, the heat-resistant insulating film 17 is adhered to the lower surface of the bulb 11 with an adhesive.

The cold cathode fluorescent lamp 10 having such a structure is
Since one flat surface faces the opening of the reflector 3, the direct light coming from a wide surface can be effectively used. A planar heater 15 is provided on the outer surface of the valve 11,
Since heating can be performed by the heater 15, when the ambient temperature is extremely low, when the heater 15 is energized and the bulb 11 is heated, the starting characteristics and the light emission characteristics of the lamp 10 are improved.

Moreover, since the sheet heater 15 of this embodiment has a single-sided structure in which a heat-resistant insulating film 17 is provided on one side surface of the sheet heating element 16, it is more flexible than a double-sided laminate. Increase. For this reason, the valve 1 is easily bent to conform to the curved surface shape of the outer surface of the valve 11 and has little elastic return.
1 does not rise from the outer surface, and the adhesion is improved.

In addition, since the other side surface of the sheet heating element 16 is in direct contact with the outer surface of the bulb 11, the heat conduction efficiency of the sheet heating element 16 is improved. Therefore, the heating performance of the valve 11 by the heating element 15 is improved.

Although the lamp 10 is housed in the gutter-shaped reflector 3 in the above embodiment, the reflector 3 may be omitted.
That is, if the aperture-type cold cathode fluorescent lamp shown in FIG. 4 is used as the lamp 10, the reflector 3 becomes unnecessary.

The aperture-type cold-cathode fluorescent lamp has a reflective film 20 on the inner surface of the bulb 11 except for a predetermined circumferential area and a fluorescent film 14 on the inner surface of the reflective film 20 except for a predetermined circumferential area. The portion where the reflection film 20 and the phosphor film 14 are not formed is a transparent portion, and such a transparent portion continuously forms the strip-shaped light transmitting portion 21 along the axial direction of the bulb 11. Formed
This light transmitting part 21 is called a slit part or an aperture part.

In the case of such a configuration, the light transmitting portion 2
Since the light is emitted through the light source 1, a directionality is generated in the irradiation direction, and the special reflector 3 is not required. In particular, the light transmitting portion 21 is provided on one flat side surface of the flat valve 11 as shown in the figure.
, A large area can be effectively used.

Further, a fine unevenness is formed on the surface of the light transmitting portion 21 to form a diffusion surface (not shown), or the light is transmitted to the outer surface of the light transmitting portion 21 as in another embodiment shown in FIG. When the diffusion film 22 is formed, the above-described light diffusion plate 5 can be omitted.

The present invention is not limited to a cold cathode fluorescent lamp, but can be applied to a hot cathode fluorescent lamp.
Further, in the case of the above embodiment, the heat-resistant insulating film 17 was adhered to the lower surface of the bulb 11 with an adhesive, but a heat-shrinkable tube (not shown) was put on the outside of the bulb and the heat-shrinkable tube contracted. The sheet heater 15 may be pressed so as to be in close contact with the lower surface of the valve 11.

In the case of a mercury low-pressure discharge lamp in which mercury is sealed in the bulb 11, it is effective to provide the heater 15 because the mercury vapor pressure is highly temperature-dependent. However, the present invention can be applied to a rare gas discharge lamp in which only a rare gas such as xenon discharges and emits light.

Further, a lamp without the phosphor coating 14 may be used. Further, the lamp is not limited to the U-shape but may be a W-shape, a ring shape or a straight tube shape, and the cross-sectional shape is not limited to a flat shape.

According to the low-pressure discharge lamp of the first aspect, the metal sheet heating element formed on one surface of the heat-resistant insulating film comprises:
As one side of the film was placed outside the bulb excluding the illumination direction so that it touched the non-illumination direction of the bulb outer surface,
It is easy to manufacture a planar heater, can improve the heating efficiency of the bulb, and has a film in the illumination direction.
Since there is no light output, a decrease in light output can be suppressed. According to the low-pressure discharge lamp of the second aspect, in addition to the function of the first aspect, the adhesion of the planar heater can be facilitated.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a lighting device of an instrument showing an embodiment of the present invention.

FIG. 2 is a sectional view of the assembled state of the embodiment.

FIG. 3 is a sectional view of the fluorescent lamp of the embodiment.

FIG. 4 is a sectional view of a fluorescent lamp showing another embodiment of the present invention.

FIG. 5 is a sectional view of a fluorescent lamp showing still another embodiment of the present invention.

[Explanation of symbols]

10: cold cathode fluorescent lamp, 11: bulb, 12: cold cathode, 14: phosphor coating, 15: sheet heater, 16: sheet heating element, 17: insulating film.

Continuation of the front page (56) References JP-A-63-34846 (JP, A) JP-A-4-155743 (JP, A) JP-A-2-86046 (JP, A) Jpn. , U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01J 61/52

Claims (2)

(57) [Claims] 1. A bulb in which a discharge medium is sealed; and a metal sheet heating element formed on one surface of a heat-resistant insulating film, wherein the heating element contacts a non-illumination direction of an outer surface of the bulb. one side is divided illumination direction of the valve of
And a sheet heater disposed outside. 2. The low-pressure discharge lamp according to claim 1, wherein the planar heater is bonded via an adhesive outside the bulb.