JPH03179485A - Lighting device - Google Patents

Abstract

PURPOSE:To hold the mercury vapor pressure in a lamp constant by installing a circuit board at one end of a casing while a gap is left, and projecting a thin pipe which contains the amalgam of a fluorescent lamp from the casing and positioning it in the space between the casing and circuit board. CONSTITUTION:Both end parts of the lamp 6 penetrate a lamp holder 13 and are led out of the casing 1, and the thin pipe 11 which contains the amalgam also projects from the casing 1. High-frequency illumination circuit components are mounted on the wiring board 20, which is fixed to a support stay to one end wall of the casing 1 across the gap 25. Then the electrodes 10 of the fluorescent lamp 6 which are led out of the casing 1 and the thin pipe 11 are positioned in the gap 25 between the wiring board 20 and casing 1. This space 25 is surrounded with the casing 1 and circuit board 20 and the influence of external temperature, i.e. disturbance is hardly generated. Consequently, temperature variation of the amalgam put in the thin pipe is reducible and variance in the mercury vapor pressure in an illumination state is also reducible.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is used for backlights of liquid crystal display devices, etc., and uses a fluorescent lamp filled with amalgam as a mercury vapor source as a light source. The present invention relates to a lighting device.

(Prior art) Backlights for liquid crystal display devices, etc. house a light source in a casing, reflect the light emitted from the light source on a reflective surface inside the casing, and send this reflected light to an illumination section on the top surface of the casing. The light is diffused through a light diffusion plate and illuminated on the back of the liquid crystal display panel.

As the light source, hot cathode or cold cathode fluorescent lamps are widely used. Fluorescent lamps have various advantages over incandescent light bulbs, such as superior luminous efficiency, less heat generation, and longer lifespan.Furthermore, because they have a long light-emitting section, they can ensure a large light-emitting area with uniform brightness.

By the way, when a fluorescent lamp is used as a backlight for the above-mentioned liquid crystal display device, the lamp is housed in a sealed or nearly sealed casing, which impairs the lamp's heat dissipation and causes the temperature of the bulb to rise. Rise.

For this reason, when pure mercury is used as a mercury vapor supply source in the fluorescent lamp, the mercury vapor pressure within the bulb exceeds the optimum value, resulting in a problem of low luminous efficiency and reduced luminous flux.

To prevent such problems, amalgam is used instead of pure mercury as the mercury vapor source. Since the vapor pressure of amalgam is lower than that of pure mercury, the lamp cannot be used under the above-mentioned high temperature conditions. It is possible to control the mercury vapor pressure within an appropriate range, and the luminous efficiency can be increased.

In such a fluorescent lamp, a stem is attached to each end of a bulb with a phosphor coating formed on the inner surface, electrodes are attached to these stems, and one stem has a thin tube that communicates with the discharge space inside the bulb. A structure is adopted in which the amalgam is housed within the thin tube.

By the way, when the above-mentioned fluorescent lamp is housed in a casing, if the thin tube part containing the above-mentioned amalgam is housed in the casing, the temperature of the amalgam may still become too high, and the mercury vapor pressure inside the lamp may exceed the appropriate pressure. .

Also, when the electrode part of the lamp is housed in the casing,
This electrode section faces the back surface of the liquid crystal display panel, and there is a fear that heat generated at the electrode section will be transmitted to the liquid crystal and cause thermal deterioration of the liquid crystal. For this reason, it is desirable that the electrode be disposed so as to protrude outside the casing. In this case, the capillary portion containing the amalgam also protrudes from the casing.

(Problem to be Solved by the Invention) As described above, when the capillary portion containing amalgam is made to protrude from the casing, if the outside temperature changes rapidly, the temperature of the capillary will not be constant, and the temperature of the amalgam will change greatly.
There is a concern that the mercury vapor pressure inside the lamp may vary.

According to the present invention, when the thin tube section containing the amalgam is made to protrude from the casing, the temperature of the amalgam can be kept constant by making it difficult to receive dynamic effects from the outside air temperature, and the mercury vapor pressure inside the lamp can be kept constant. The aim is to provide a lighting device that can.

[Structure of the Invention] (Means for Solving the Problems) A lighting device that uses a fluorescent lamp as a light source requires a lighting circuit to keep the lamp lit, and a high-frequency lighting circuit device, ballast, etc. are used. It will be done. When these lighting circuit components are placed near the lamp, wiring becomes easier. Therefore, it is conceivable to mount the lighting circuit components on a circuit board and install this circuit board at one end of the casing.

Therefore, in order to achieve the above object, the present invention includes a circuit board installed at one end of a casing with a gap between the circuit board and the casing, and a thin tube containing an amalgam of a fluorescent lamp protruding from the casing. It is characterized in that it is located in a space between the casing and the circuit board.

(Function) According to the present invention, the thin tube of the lamp protruding from the casing is located in the space secured between the casing and the circuit board, so it is hardly affected by external disturbances. Temperature changes in the amalgam can be reduced, and variations in mercury vapor pressure during lighting can be reduced.

Furthermore, since the thin tube is arranged in the space between the casing and the circuit board, problems such as damage caused by hitting the thin tube against something during assembly or other handling are prevented.

(Example) The present invention will be described below based on a first example shown in FIGS. 1 to 4.

In the figure, reference numeral 1 denotes a shallow dish-shaped casing with an open top, and is made of metal such as aluminum or synthetic resin such as polycarbonate, and the opening on the top is used as an irradiation part 2.

The entire inner surface of the casing 1 is a reflective surface 3, and the light reflected by the reflective surface 3 is directed toward the irradiation section 2.

A lamp lead-out notch 4 is provided on the side wall at one end of the casing 1.
．． These notches 4.4 are formed by cutting down the side wall, and these cut down portions extend outward to form support stays 5.5.

A bent fluorescent lamp 6 is accommodated in the casing 1 . The lamp 6 of this embodiment is a W-shaped cold cathode fluorescent lamp. That is, 7 is a valve bent into a W-shape, and this valve 7 is provided with straight portions that are substantially parallel to each other, and these straight portions are U-shaped bent portions ga and 8b.

Conducted at 8C.

Both ends of the bulb 7 are sealed with button stems 9.9, which are equipped with cold cathode type electrodes 10.
10 is installed.

The cold cathode type electrode 10.10 is constructed by joining an electrode shaft 10b to an electrode head portion 10a, for example, as shown in FIG. 4, and the electrode head portion 10a of this embodiment has a roof shape. There is.

Normally, the life of an electrode is related to the electrode surface area and the lamp current, and for cold cathodes, the electrode surface area/lamp current is 1.5.
It is necessary to satisfy the condition +a+e2/■^. For this reason, we want to increase the electrode surface area.

In the above embodiment, the protruding pieces 100, 100 are formed on the side surfaces of the roof-shaped electrode head portion 10a to increase the electrode surface area. It satisfies the condition of 5mm2/mA.

The structure of the cold cathode electrode may be a cylindrical electrode head portion 10aa as shown in FIG. 101 may be formed.

The fluorescent lamp 6 has thin tubes 11.11 protruding from the button stem 9°9.
1 is electrically connected to the inside of the valve 7.

Note that one of the thin tubes is formed of an exhaust pipe.

At least one of these thin tubes 11.11 houses amalgam (not shown).

A phosphor film (not shown) is formed on the inner surface of the bulb 7, and a predetermined amount of a starting rare gas such as argon or xenon is sealed inside the bulb 7.

The fluorescent lamp 6 having such a structure is housed in the casing 1. In this case, lamp holders 12.13.13 are attached to the casing 1, and the lamp 6 is supported on these lamp holders 12.13.13.

These lamp holders 12, 13, 13 are made of an elastic material such as rubber, and are fixed to the casing 1 by suitable means such as adhesive. The lamp holder 12 is arranged inside the other end of the casing 1, and has two U-shaped bent portions 8a of the bulb 7 bent into a W-shape.

It has recesses 12a and 12b into which the recesses 8b fit. Further, the other lamp holder 13.13 is attached to the casing 1.
An insertion hole 13 is fitted into a lamp lead-out notch 4.4 formed at one end, and through which both ends of the lamp 6 are passed.
a, 13a.

Therefore, the fluorescent lamp 6 has two U points on the bulb 7.
The shaped bent portions 8a, 8b and both ends are the lamp holder 12.1.
3.13, so it can be attached to the casing 1.

In this case, both ends of the lamp 6 are attached to lamp holders 13.13.
The electrode 10.10 is located outside the casing 1 through the insertion holes 13a, 13a, and the thin tube 11.11 containing the amalgam also projects outside the casing 1. .

I'm being kicked. The wiring board 20 has high-frequency lighting circuit components mounted thereon, and the high-frequency lighting circuit components include, for example, an inverter transformer 21, a capacitor 22, and a choke 23.
, noise filter 24, etc.

Such a wiring board 20 faces one end wall of the casing 1 and is fixed to the support stays 5, 5 with a gap 25 between the wiring board 20 and the one end wall of the casing 1.

Then, the electrode 10.10 of the fluorescent lamp 6 led out of the casing 1 and the thin tube 1 containing the amalgam
1.11 is located in a gap 25 secured between the wiring board 20 and the casing 1.

On the other hand, a light diffusing and transmitting plate 15 is provided at the upper opening of the casing 1.
is installed. The light diffusing and transmitting plate 15 is made of a milky white material such as acrylic resin and has a diffusive and transmitting effect on light. Thick portions 16 are formed in opposing portions. These thick parts 16...
The wall thickness gradually decreases as the distance from the valve 7 increases.

Furthermore, a liquid crystal display panel 17 is disposed above the light diffusing and transmitting plate 15. The liquid crystal display panel 17 has a liquid crystal display surface 18 facing the light diffusing and transmitting plate 15 .

The operation of the embodiment with such a configuration will be explained.

When the fluorescent lamp 6 is energized, the lamp 6 emits light in a shape along the W-shaped bulb 7.

A part of the light emitted from the fluorescent lamp 6 is reflected by the reflective surface 2 formed on the inner surface of the casing 1 and directed to the light diffusing and transmitting plate 15 in the opening, and the remaining light is directly reflected by the light diffusing and transmitting plate 15. heading to Therefore, all the light emitted from the lamp 6 is irradiated to the outside through the light diffusing and transmitting plate 15.

In this case, since the thick portions 16 are formed on the outer surface of the light diffusing and transmitting plate 15 facing the substantially parallel linear portions of the W-shaped bulb 7, the thick portions 16 are directly above the bulb 7.・ exists, and this thick part】6... reduces the amount of light transmission, and
Since the wall thickness becomes thinner as the distance from the thick portion 16 increases, the amount of light transmitted increases. Therefore, the light diffusing and transmitting plate 15 eliminates uneven brightness.

For this reason, the brightness distribution on the light diffusing and transmitting plate 15 is equalized, and the liquid crystal display surface 1 of the liquid crystal display panel 17 is
8 can be irradiated with uniform brightness throughout without causing uneven brightness.

In addition, since the lamp 6 is housed in the casing 1, heat dissipation cannot be expected, so even if the temperature of the bulb 7 becomes high, since amalgam is used as the mercury vapor supply source, the mercury vapor pressure can be kept within an appropriate range. can be controlled to,
Luminous efficiency can be increased.

The amalgam has a thin tube 1 protruding from the valve 7.
Since the thin tube 11 is arranged to protrude outside the casing 1, the temperature of the thin tube 11 does not rise, and the coldest part occurs in the thin tube 11, so that the mercury vapor pressure is appropriately suppressed.

In this case, since the thin tube 11 is located in the space 25 secured between the casing 1 and the circuit board 20, this space 25 is surrounded by the casing 1 and the circuit board 20, so that the influence of external temperature is reduced. In other words, it is difficult to receive disturbances, and therefore, it is possible to reduce temperature changes in the amalgam housed in the thin tube 11, and it is possible to reduce variations in mercury vapor pressure during lighting.

Further, since the thin tube 11 is arranged in the space 25 between the casing 1 and the circuit board 20, the circuit board 20
1 and prevents problems such as the thin tube 11 hitting something and being damaged during handling such as assembly.

Furthermore, in the case of this embodiment, since the electrodes 10, 10 sealed at the ends of the bulb 7 are also located outside the casing 1, the electrodes 10, 10, which are heat sources, are connected to the liquid crystal display panel 1.
7, the heat generated at the electrodes 10 and 10 is prevented from being transmitted to the liquid crystal, and thermal deterioration of the liquid crystal is prevented.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and for example, the fluorescent lamp is not limited to a bent shape such as a W shape or a U shape, but may be a straight tube shape, etc., and one lamp may be used. You may also use more than one.

Furthermore, the cross-sectional shape of the bulb 7 in the lamp 6 (the cross-sectional shape of the discharge space) is not limited to a circular shape, but may be a flat shape. If the lamp has a flat shape, the side surface with a large light emitting area can face the light diffusing and transmitting plate 15, and the effective utilization rate of the light emitted from the lamp becomes high.

Furthermore, the present invention is not limited to cold cathode fluorescent lamps.
It may be a hot cathode type.

Furthermore, the circuit board 20 is not necessarily one on which the high-frequency lighting circuit components 21 to 24 are mounted; for example, in this type of lighting device, a heater may be used to warm the lamp, and in that case, a temperature sensor or temperature fuse may be used. Therefore, a wiring board may be used as a wiring terminal for these heaters, temperature sensors, and temperature fuses (Japanese Patent Application No. 1999).
253563), such a wiring board may be used.

[Effects of the Invention] As explained above, according to the present invention, the thin tube of the lamp protruding from the casing is located in the space formed between the casing and the circuit board, so it is not affected by disturbances. Therefore, it is possible to reduce temperature changes in the amalgam housed in the capillary tube, and it is possible to reduce variations in mercury vapor pressure during lighting. Furthermore, since the thin tube is arranged in the space between the casing and the circuit board, problems such as the thin tube being damaged by hitting something during assembly or other handling can be prevented.

[Brief explanation of drawings]

1 to 4 show an embodiment of the present invention, in which FIG. 1 is an exploded perspective view of the whole, FIG. 2 is a plan view with the light diffusion and transmission plate removed, FIG. 3 is a cross-sectional view, and FIG. FIG. 4 is a perspective view of a cold cathode, and FIG. 5 is a perspective view of a cold cathode showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Casing, 3... Reflective surface, 4... Notch, 5... Support stay 6... Fluorescent lamp, 7...
・Valve, 9...button stem, 10...cold cathode,
11... Thin tube, 15... Light diffusing and transmitting plate, 17...
Liquid crystal display panel, 20... wiring board, 25... gap.

Claims (1)

[Claims] A casing houses a fluorescent lamp comprising amalgam contained in a thin tube protruding from the end of the bulb, and the light emitted from the lamp is emitted from an irradiation part formed on one surface of the casing. In the lighting device, a circuit board is installed at one end of the casing with a gap between it and the casing, and a thin tube containing the amalgam of the fluorescent lamp protrudes from the casing. A lighting device characterized in that it is located in a space between the casing and the circuit board.