JPH03274604A - Illuminating device - Google Patents

Abstract

PURPOSE:To prevent a lamp current from leaking through a radial noise preventing mesh by forming a transparent electric insulation layer on the surface of a radiated noise preventing mesh at last on a surface facing a lamp. CONSTITUTION:Electric insulation films 20 are laminated on the under-side surface of a radiated noize preventing mesh 15, that is a surface facing a lamp 6, so that mesh 15 and the lamp 6 are electrically insulated and isolated from each other. Leak of a lamp current to the radiated noise preventing mesh 15 can thus be prevented, and the lamp current is given to the lamp effectively, thereby the light emission efficiency is improved, and the illuminance is improved.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Field of Industrial Application) The present invention uses a low-pressure discharge lamp such as a fluorescent lamp as a light source,
The present invention relates to a lighting device suitable for backlights of liquid crystal televisions and liquid crystal meters.

(Conventional technology) LCD televisions, LCD meters, etc. are designed to illuminate the LCD surface by shining light from the back of the transmissive LCD panel.
Such a backlight requires an illumination device that can illuminate a liquid crystal surface having a predetermined spread with uniform brightness as a whole.

This type of backlight has traditionally housed a hot cathode or cold cathode fluorescent lamp in a shallow dish-shaped casing.
A lighting device is used in which the light emitted from the lamp is reflected by a reflective surface formed in the casing and illuminated on the back side of the liquid crystal panel through a light diffusing and transmitting plate installed in the opening of the casing.

When a hot cathode or cold cathode fluorescent lamp is used as a light source, compared to an incandescent lamp, these fluorescent lamps have superior luminous efficiency, generate less heat, have a longer lifespan, and have a longer discharge path, so their light emitting area is smaller. It has the advantage that it is large and the light distribution can be easily made uniform. In particular, in the case of a fluorescent lamp, it is easy to configure the discharge path into a bent shape, such as a U-shape or a W-shape, and a fluorescent lamp with such a bent shape has a planarly wider light-emitting surface. Therefore, it is advantageous to illuminate a display surface having a predetermined spread with uniform brightness.

By the way, when a fluorescent lamp is lit using a high frequency power source, flickering is reduced and the lamp life is extended. For this reason, lighting is performed by connecting to a high frequency lighting circuit device such as an inverter circuit.

However, when a fluorescent lamp is lit at a high frequency, there is a concern that high frequency noise will be emitted from the lamp.

When such a lamp is housed in a casing, high-frequency noise from the lamp can be shielded by forming the casing from a conductive material and covering the opening of the casing, that is, the irradiation part, with a conductive material.

Therefore, a structure is adopted in which the casing is made of conductive aluminum and a conductive mesh for preventing radiation noise is provided in the opening.

(Problem to be Solved by the Invention) However, when the conductive mesh for preventing radiation noise is provided at the opening of the casing as described above, the lamp current leaks from the lamp through the mesh for preventing radiation noise, which reduces the luminous efficiency. A problem was observed in which the brightness of the lamp decreased.

The present invention aims to provide a lighting device that prevents lamp current from leaking through a mesh for preventing radiation noise.

[Structure of the Invention] (Means for Solving the Problems) The present invention is characterized in that a transparent electrically insulating layer is formed on the radiation noise prevention mesh at least on the surface facing the lamp.

(Function) According to the present invention, since the transparent electrical insulating layer provides electrical insulation between the radiation noise prevention mesh and the lamp, lamp current will not leak from the lamp toward the radiation noise prevention mesh side. .

This improves luminous efficiency and increases brightness.

(Embodiment 1) The present invention will be described below based on an embodiment shown in the drawings.

In the figure, reference numeral 1 denotes a tray-shaped casing with an open top, made of a metal such as conductive aluminum, and has a reflective surface 2 formed on its inner surface.

The upper surface opening of the casing 1 is used as an irradiation part, and a fixed circumferential flange 3... is formed in this opening, and a screw hole 4... is formed in the fixed circumferential flange 3... There is.

A bent fluorescent lamp 6 is accommodated in the casing 1 . The fluorescent 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 8a8b, 8c, and 8d that are substantially parallel to each other, and these straight portions ga, 8b, 8c, and 8d are bent into a U-shape. Part 9a
.

9b and 9c are electrically connected. Cold cathode type electrodes 10.10 are sealed to both ends of the bulb 7, and a base 11.11 is attached to the ends.

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

The fluorescent lamp 6 having such a structure is housed in the casing 1, and the caps 11 and 11 at both ends are fitted into the mounting holes 12 formed in the side wall of the casing 1, and then applied with an appropriate means such as adhesive. is fixed.

Further, the fluorescent lamp 6 is electrically connected to a high frequency lighting circuit device (not shown) so that it can be lit at high frequency.

A mesh 15 for preventing radiation noise is provided at the opening of the casing 1. This radiation noise prevention mesh 15 is formed by punching conductive metal and integrally forms a surrounding frame part 16 and a central mesh part 17. It is designed to cover the opening of the A collar 18 is attached to the frame 16 of the radiation noise prevention mesh 15.
are formed, and holes 19 are formed in the flange 18 for attaching these.

An electrical insulating layer is formed on at least the lower surface side (upper and lower surfaces may be used) of the radiation noise prevention mesh 15, that is, the surface facing the lamp 6.

In this embodiment, the electrical insulating layer is formed of a transparent insulating film 20, and this insulating film 20 is laminated on the lower surface of the radiation noise prevention mesh 15 using, for example, an adhesive.

Note that the insulating film 20 does not cover the flange 18 when the radiation noise prevention mesh 15 is attached;
... is a fixed circumferential collar 3 provided at the top opening of the casing 1
It is designed to polymerize and come into contact with...

Further, a light diffusing and transmitting plate 25 is attached to the upper opening of the casing 1 on the mesh 15 for preventing radiation noise. The light diffusing and transmitting plate 25 is made of acrylic resin or the like and has a milky white color and has a light diffusing and transmitting function. , 8b, 8c, and 8d are formed with thick portions 26.... The thickness of these thick portions 26 gradually becomes thinner as they move away from the valve 7.

Connecting holes 27 are formed at the four corners of the light diffusing and transmitting plate 25, and screws 28 are inserted into these holes 27.

The screws 28 pass through the connection holes 27 of the light diffusion and transmission plate 25, and pass through the radiation noise prevention mesh 1.
5 is attached by passing through one hole and screwing into a screw hole 4 formed in the upper opening of the casing 1.

Therefore, the light diffusing and transmitting plate 25 and the radiation noise prevention mesh 15 are fastened together to the screw casing 1 by screws 28.

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

When the fluorescent lamp 6 is turned on by applying high frequency power, 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 transmitted to the casing 1.
The remaining light is reflected by the reflective surface 2 of the opening and directed toward the light diffusing/transmitting plate 25 at the opening, and the remaining light is directed directly toward the light diffusing/transmitting plate 25. Therefore, almost all of the light emitted from the lamp 6 is irradiated to the outside through the light diffusing and transmitting plate 25.

In this case, the substantially parallel straight portion 8a of the W-shaped valve 7,
8b, 8c, and 8d are formed on the outer surface of the light diffusing and transmitting plate 25, so that the thick portion 26 exists directly above the bulb 7, and this thick portion 26 prevents light from flowing. In addition to reducing the amount of light transmitted, since the wall thickness becomes thinner as the distance from the thick portion 26 increases, the amount of light transmitted increases. Therefore, the light diffusing and transmitting plate 25
has the effect of eliminating brightness unevenness by itself.

For this reason, the brightness distribution on the light diffusing and transmitting plate 25 is equalized, uneven brightness is reduced, and uniform brightness can be achieved over the entire surface.

The casing 1 is made of a metal such as conductive aluminum, and the opening of the casing 1 is provided with a mesh 15 for preventing radiation noise, so that high frequency noise emitted from the fluorescent lamp 6 during lighting is prevented. It can be shielded and prevent high frequency radiation disturbance.

An electrically insulating film 20 is laminated on the lower surface of the radiation noise prevention mesh 15, that is, the surface facing the lamp 6, so that the mesh 15 and the lamp 6 are electrically insulated and isolated. Therefore, the lamp current is prevented from leaking into the radiation noise prevention mesh 15, and the lamp current is effectively applied to the lamp, resulting in improved luminous efficiency and brightness.

Note that the radiation noise prevention mesh 15 is attached to the collar 18.
... is a fixed circumferential collar 3 provided at the top opening of the casing 1
..., so both the radiation noise prevention mesh 5 and the casing 1 are electrically connected, and if only one of them is connected to the ground, it can be used for the ground connection of both. be able to.

Furthermore, the present invention is not limited to the above embodiments,
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 or the like, and one or a plurality of fluorescent lamps may be used.

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 25, and the effective utilization rate of the light emitted from the lamp becomes high.

Furthermore, the present invention may be a rare gas discharge lamp in which the bulb is not filled with mercury but only with a rare gas.

The insulating layer of the radiation noise prevention mesh: L15 is
The electrical insulating film 20 is not limited to being laminated, but may be coated with an insulating paint.

Further, the casing 1 may be made of a resin such as polycarbonate, and may be provided with a conductive structure for preventing radiation noise by providing a conductive coating or forming a reflective surface of a conductive material.

[Effects of the Invention] As explained above, according to the present invention, a transparent electrically insulating layer is provided on the radiation noise prevention mesh facing the lamp, so that the radiation noise prevention mesh and the lamp are electrically insulated. This prevents lamp current from leaking from the lamp toward the radiation noise prevention mesh side. This improves luminous efficiency and increases brightness.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show one embodiment of the present invention, in which FIG. 1 is an exploded perspective view of the whole, and FIG. 2 is a sectional view. 1...Casing, 6...Fluorescent lamp, 7...
Bulb, 10... Electrode, 15... Radiation noise prevention mesh, 20... Insulating film, 25...
Light diffusion and transmission plate.

Claims (1)

[Claims] A lighting device in which a low-pressure discharge lamp lit by a high-frequency power source is housed in a conductive casing having an irradiation part on one side, and a conductive mesh for preventing radiation noise is provided in the irradiation part of the casing. A lighting device characterized in that a transparent insulating layer is formed on the surface of the prevention mesh facing the discharge lamp.