JPH0444009A - Illuminator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a lighting device used as a backlight of a liquid crystal display device or the like.

(Prior art) Instrument panels with liquid crystal displays, liquid crystal display televisions, etc. are designed to emit light from the back of the liquid crystal panel, and as such a back lighting device, the conventional device shown in Fig. 7 is used. It has been known.

That is, 50 is a light guide, and this light guide 50 is formed in the shape of a plate or block of a light transmitting material having a milky white light diffusing effect, such as acrylic resin.

Reference numeral 51 denotes a low-pressure discharge lamp as a light source, which is formed of, for example, a straight-tube hot cathode or cold cathode fluorescent lamp. The fluorescent lamp 51 is disposed outside the light guide 50 facing one end surface of the light guide 50, and the light emitted from the lamp 51 is transmitted from the one end surface of the light guide 50 to the light guide 50. Light enters the light guide 50, is diffused by the light guide 50, and is emitted from one side, for example, the top surface.

The outer peripheral surface of the light guide 50 is surrounded by a casing 52, except for the light introduction end surface and the upper irradiation surface, and the inner surface of the casing 52 is a reflective surface 53.

Therefore, the light introduced from one end surface of the light guide 50 is
In the process of passing through the light guide 50, the light is diffused, reflected by the surrounding reflective surface 53, and emitted from the upper surface. This diffused light is transmitted to a liquid crystal display plate 54 disposed opposite to the upper surface of the light guide 50.
Illuminates the bottom, or back, of the

In this case, since the light emitted from the lamp 51 is emitted in the radial direction of the straight tube type bulb, there is a problem that the amount of light directed toward the light introduction end face of the light guide 50 is reduced. Efforts have been made to surround the area with reflective mirrors or use aperture-shaped fluorescent lamps. The illustrated example shows a case where an aperture-type fluorescent lamp is used as the fluorescent lamp 51, and by covering the outer periphery of the bulb except for a part in the circumferential direction with a light shielding film 55 or a reflective film, only one side of the bulb is exposed to light. This is a light opening 56 that can transmit light.

Therefore, the light emitted from the lamp 51 is emitted only from the light opening 56, and this light heads toward one end surface of the light guide 50,
The light is introduced into this light guide 50. Therefore, the light guide 50
The amount introduced will increase, and the effective utilization rate will improve.

(Problem to be Solved by the Invention) However, as in the past, an aperture-type fluorescent lamp is used as a light source, or the light emitted from the lamp is reflected by a reflecting mirror and directed toward one end surface of the light guide 50. Even if devised to dodge the lamp, a gap may occur between the lamp 51 and the light guide 50 and the light may leak outside through this gap, reflection loss may occur in the light-shielding film 55 surrounding the lamp, a reflective film, or a reflecting mirror, and furthermore. Due to factors such as reflection at the light-introducing end face of the light guide 50, the effective utilization rate of the light emitted from the lamp is not necessarily sufficient.

Furthermore, since the fluorescent lamp 51 is installed outside the light guide 50, there is also the problem that the overall space becomes large.

Therefore, an object of the present invention is to provide a lighting device that can further improve the effective utilization rate of light emitted from a lamp without causing leakage loss or reflection loss to the outside, and can be made smaller. It is something.

[Configuration of the Invention (Means for Solving Problems) The present invention is characterized in that an insertion hole is formed in the light guide, and a low-pressure discharge lamp is inserted through the insertion hole.

(Function) According to the present invention, the light emitted from the low-pressure discharge lamp inserted into the insertion hole formed in the light guide directly and entirely enters the light guide surrounding the entire circumference, and is emitted to the outside. No leakage or reflection loss occurs.

Therefore, the effective utilization rate of light increases. Furthermore, since the ζ discharge lamp is inserted into the insertion hole, the overall configuration becomes compact.

(Example) The present invention will be described below based on a first example shown in FIGS. 1 and 2.

In the figure, reference numeral 1 denotes a light guide, and the light guide 1 is made of a milky white light diffusing and transmitting material such as acrylic resin, and is formed into a plate shape or a block shape. This light guide 1 is surrounded by a casing 2 except for one side, that is, the top surface, and the inner surface of this casing 2 is a reflective surface 3.

For example, two through holes 4, 4 are formed in the light guide 1. These insertion holes 4, 4 are parallel to each other and penetrate horizontally. That is, the insertion hole 4° 4 is parallel to the upper surface of the light guide 1.

In the case of this embodiment, the dimension a from the insertion holes 4, 4 to the top surface of the light guide 1 is larger than the XJ dimension from the insertion holes 4, 4 to the bottom surface of the light guide 1 (a>b ) is formed.

A low-pressure discharge lamp serving as a light source, for example, a straight tube cold cathode fluorescent lamp 5, passes through these insertion holes 4, 4, respectively. These cold cathode fluorescent lamps 5.5 each have cold cathodes 6, 6 sealed at both ends of a straight bulb, and a phosphor coating (not shown) formed on the inner surface. Predetermined amounts of mercury and rare gas are sealed inside these bulbs.

Such straight tube cold cathode fluorescent lamps 5, 5 are inserted into the insertion hole 4 with their respective ends protruding to the outside of the light guide 1.
, 4 through it.

Note that 7 is a liquid crystal display plate disposed opposite to the upper surface of the light guide 1, and is irradiated with light emitted from the upper surface of the light guide 1.

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

When the fluorescent lamps 5, 5 are turned on, these lamps 5,
5 emits light in the radiation direction of the bulb. The light emitted from these lamps 5, 5 enters the light guide 1 through the inner surface of the insertion holes 4, 4 surrounding the lamps.

In this case, since the lamp 5.5 is surrounded by the light guide 1, all the light emitted in the radial direction enters the light guide 1. Therefore, before the light enters the light guide 1, there is no leakage to the outside or reflection loss, and the effective utilization rate of the light is increased.

The light that has entered the light guide 1 in this way is diffused inside the light guide 1 by the light diffusion effect of the light guide, and this light guide 1
After being reflected by the reflective surface 3 of the casing 2 surrounding the casing 2, it is emitted to the outside from the upper surface. Therefore, the back surface of the liquid crystal display board 7 is illuminated.

Since the fluorescent lamp 5 of this embodiment is of a cold cathode type, the temperature rise of the bulb is smaller than that of a hot cathode lamp, and therefore, even if it is inserted into the insertion holes 4, 4, thermal deterioration is less likely to occur. Less is. Moreover, since the ends of each lamp 5, 5 protrude outside the light guide 1, the coldest part occurs at the end of the bulb outside the light guide 1, and mercury condenses. Therefore, the proportion of mercury remaining in the portions of the lamps 5, 5 located inside the respective insertion holes 4, 4 is small, and therefore the light absorption effect of mercury is small, so that the luminous efficiency is improved.

In addition, in the case of this embodiment, the position where the insertion holes 4, 4 are formed is below the middle of the light guide 1, and the dimension a from the insertion hole 4°4 to the upper surface of the light guide 1 is The dimension from the holes 4, 4 to the bottom of the light guide l is larger than ((a>b)
Therefore, variations in the illuminance distribution on the upper surface of the light guide 1 can be reduced. That is, on the light emitting surface of the upper surface of the light guide 1, the position closest to each lamp 5, 5, that is, directly above the insertion holes 4, 4 is the brightest, and the light becomes farther from this position in the direction perpendicular to the bulb axis. The brightness tends to decrease as the time increases. However, by increasing the wall thickness a directly above the insertion hole 4.4, the light that goes directly from the lamp 5.5 toward the top surface of the light guide 1 is diffused as much as possible, thereby increasing the brightness on the top surface of the light guide 1. It is possible to approach equalization.

Therefore, the back surface of the liquid crystal display board 7 is evenly irradiated.

Furthermore, since the lamps 5, 5 are disposed so as to penetrate through the insertion hole 4.4 of the light guide 1, a small space is required and the overall structure is made small and compact.

Note that the present invention is not limited to the first embodiment described above.

That is, in the case of the second embodiment shown in FIG.
In order to further increase the thickness directly above the insertion holes 4, 4, a protruding thick portion 10,]0 is formed on the upper surface of the holder. In addition, the insertion hole 4
, By cutting off the other parts except for the part directly above 4,
A similar shape may be configured.

With this configuration, the light guide 1 can be directly connected to the lamp 5.5.
The light directed toward the upper surface can be further diffused, and the luminance distribution on the upper surface of the light guide 1 can be made even more uniform.

In addition, in the case of the third embodiment shown in FIG. 4, the insertion hole 20.
20 has a flat shape such as an ellipse or an ellipse in cross section,
Lamps 21.21 inserted into these insertion holes 20.20
It also has an oblate shape such as an ellipse or an ellipse in cross section.

Even in this case, it is effective to equalize the luminance distribution on the upper surface of the light guide 1.

Furthermore, in the case of the fourth embodiment shown in FIG. 5, the light guide 1 is divided into upper and lower halves with the insertion holes 4, 4 as boundaries, and these divided light guides 1a and 1b are brought together to form a light guide. 1 was formed.

According to such a structure, the insertion holes 4, 4 can be easily formed, the light guide 1 can be made of not only resin but also other glass materials, and the lamp can be easily attached.

Furthermore, in the case of the fifth embodiment shown in FIG.
4 is inserted.

In this way, there are fewer electrodes than when using two straight tube lamps, making it easier to connect the power supply.
Stabilizers etc. become easier.

The lamp is not limited to a cold cathode fluorescent lamp, but may be of a hot cathode type, or may be a rare gas discharge lamp such as a xenon lamp.

[Effects of the Invention] As explained above, according to the present invention, since the low pressure discharge lamp is inserted into the insertion hole formed in the light guide, the light emitted from the low pressure discharge lamp is transmitted through the guide surrounding the entire circumference in the circumferential direction. The light enters the light body directly and completely, and there is no leakage to the outside or reflection loss. Therefore, the effective utilization rate of light increases. Furthermore, since the discharge lamp is inserted into the insertion hole, the overall configuration becomes compact.

[Brief explanation of drawings]

1 and 2 show a first embodiment of the present invention, FIG. 1 is a sectional view, FIG. 2 is a plan view, and FIG. 3 is a second embodiment of the present invention.
4 is a sectional view showing the third embodiment of the present invention, FIG. 5 is a sectional view showing the fourth embodiment of the present invention, and FIG. 6 is a sectional view showing the fourth embodiment of the present invention. FIG. 7 is a plan view showing the fifth embodiment of the present invention, and FIG. 7 is a sectional view showing the conventional structure. 1... Light guide, 2... Casing, 4.20...
Insertion hole, 5.21.30... Fluorescent lamp, 7...
LCD display board. Applicant's Representative Patent Attorney Takehiko Suzue

Claims (1)

[Claims] A lighting device comprising a low-pressure discharge lamp and a light guide that conducts light emitted from the discharge lamp and emits it from one side, wherein an insertion hole is formed in the light guide, A lighting device characterized in that the discharge lamp is inserted through the insertion hole.