JP2001343642A - Backlight unit for liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify return wiring of a lead wire in housing a straight tube type CCFT(cold-cathode fluorescent tube) in a case. SOLUTION: In attaching the straight tube type CCFT 2 in the case 10 the upper surface of which is opened, one lead line 62 out of the first and the second lead lines 61, 62 connected to respective electrode terminals of the CCFT 2 is return-wired along the CCFT 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit for illuminating a liquid crystal display element from the back side, and more particularly, to a technique for routing lead wires connected to a straight tube type cold cathode fluorescent tube.

[0002]

2. Description of the Related Art In order to obtain a bright display even in a dark place, a transmissive or transflective liquid crystal display element is provided with an illuminating device called a backlight unit on the back side thereof.

The light source is a cold cathode fluorescent tube (CCFT)
And EL (electroluminescence) panel, and LED, etc., but in the case of a relatively large liquid crystal display device, a CCFT (cold cathode f) capable of obtaining a sufficient light emission amount
Fluorescent tube) is generally adopted.

[0004] There are also a U-tube type and a straight-tube type CCFT.
In the case of a U-shaped tube, both electrode terminals are on the same side, so that the lead wires connected to the respective electrode terminals can be easily wired from the case to the socket. On the other hand, in the case of the straight pipe type, it is necessary to lead the lead wire connected to one of the electrode terminals to the socket via somewhere in the case. The conventional example will be described with reference to FIGS.

FIG. 5 is a plan view of the first conventional example, when the inside of the case 1 of the backlight unit is viewed from above (the liquid crystal display panel side). In the first conventional example, the lead wires of the straight tube type CCFT 2 are routed using the circuit board 3.

That is, the circuit board 3 is formed with lead patterns 31 and 32 to be soldered to the electrode terminals 21 and 22 at both ends of the CCFT 2. The connection electrodes 31a and 32a are gathered at one end of the circuit board 3 and lead wires from a socket (not shown) are soldered to these electrodes.

FIG. 6 shows a second conventional example. In this case, unlike FIG. 5, the inside of the case 1 of the backlight unit is shown in cross section. In this second conventional example, a straight pipe type CCFT2
Is connected to one of the electrode terminals 21 in advance by a lead wire 41.
Is inserted into the case 1 from the side of the case 1 in a state of being soldered.

The other electrode terminal 22 is connected to the case 1
Are soldered to the lead wires 42 wired along the bottom surface of. The lead wire 42 and the lead wire 41 together with the case 1
And is connected to a socket (not shown).

[0009]

However, the first conventional example requires a separate component such as the circuit board 3, which is not only unfavorable in terms of cost, but also involves a large number of soldering points, and thus the productivity is not good. Has a problem in terms of environmental pollution due to lead contained in solder.

In this regard, according to the second conventional example, although the circuit board 3 is not required, the case 1 must be turned upside down in order for the lead wire 32 to follow the bottom surface of the case 1, and the number of operations is increased. It is undeniable that the work becomes complicated. After attaching CCFT2 to case 1,
In the case where the CCFT 2 is exchanged, a complicated operation is similarly required. In any case, improvement of the assembling workability has been desired.

[0011]

According to a feature of the present invention,
The lead wiring of the straight tube type CCFT can be simplified with a very simple operation.

That is, according to the present invention, a straight-tube cold-cathode fluorescent tube (CCFT) is housed in a case having an open upper surface, and light is directed from the cold-cathode fluorescent tube toward the rear side of the liquid crystal display panel. In the backlight unit for a liquid crystal display device for irradiating light, one of the first and second lead wires connected to each electrode terminal provided at both ends of the cold cathode fluorescent tube is connected to one of the electrode terminals. The first lead wire is wired along the cold cathode fluorescent tube toward the other electrode terminal side, and both the first and second lead wires are drawn out of the case from the other electrode terminal side. It is characterized by having.

As described above, by arranging one of the lead wires along the cold cathode fluorescent tube, there is no need to use a circuit board as in the first conventional example, and the lead wire as in the second conventional example. Need not be wired to the bottom side of the case.

In the present invention, one of the lead wires is preferably wired just above the cold cathode fluorescent tube,
According to this, it is easy to flatten the luminance distribution of the cold cathode fluorescent lamp.

According to the present invention, the mounting operation can be completed only by inserting the cold cathode fluorescent tube into the case. However, in the case, the first lead wire for the first lead wire is provided above the main insertion portion for the cold cathode fluorescent tube. By providing a guide plate having an insertion hole formed by forming a series of sub insertion portions, the cold cathode fluorescent tube and the first lead wire can be reliably held.

[0016]

Next, an embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, this backlight unit is mounted on the back of a liquid crystal display panel (not shown), and a case 1 whose upper surface on the back side of the panel is open.
0 is provided. One of the side walls of the case 10 has a through hole 11 for inserting a straight pipe type CCFT 2 into the case 10.
Are drilled.

In this example, a rubber elbow cap 50 is attached to one end of the CCFT 2. The elbow cap 50 is forcibly fitted into the through hole 11, and
It also functions as a holder for holding CFT 2 in case 10.

The CCFT 2 has two lead wires 61 and 62.
Are connected, but as shown in FIG.
One electrode terminal 21 is connected to one of the two lead wires 61 and 62 in the elbow cap 50.

The remaining lead 62 is CCFT2
In this case, the other lead wire 62 is routed directly above the CCFT 2 and passes through the inside of the elbow cap 50 to a socket (not shown) together with the one lead wire 61. Connected.

Therefore, according to this configuration, the wiring for returning the lead wire 62 to the one electrode terminal 21 side is simplified, and the mounting operation can be completed only by inserting the CCFT 2 through the through hole 11. Note that the same effect can be obtained even if the lead wire 62 is arranged alongside or below the CCFT 2.

According to this example, the case 10 contains the CC
A guide plate 12 for holding the FT 2 and the lead wire 62 in an appropriate positional relationship is provided upright on an extension of the through hole 11.
Referring also to the cross-sectional view of FIG.
An insertion hole formed by forming a series of sub-insertion portions 122 for the lead wire 62 is formed above the main insertion portion 121 for CCFT2.

According to this, the CCFT 2 and the lead wire 62
Can be inserted into the guide plate 12 together, and even if vibration or impact is received, there is no deviation in the positional relationship between the CCFT 2 and the lead wire 62.

As shown in FIG. 3, a light diffusing plate 13 is provided on the upper surface of the case 10 to make the luminance distribution of the CCFT 2 uniform. As shown in FIG. By arranging the line 62 directly above the CCFT 2, as shown in FIG. 4, a luminance distribution with a concave central portion is obtained, so that more uniform light can be given to the liquid crystal display panel. Become like

[0025]

As described above, according to the present invention,
When storing the straight pipe type CCFT in the case, the return wiring of the lead wire is simplified, and the straight pipe type CCFT can be mounted in the case by a very simple operation, and the replacement work due to a failure of the CCFT. Can be easily replaced even when the operation is performed, and workability is improved. In addition, by arranging the lead wire directly above the CCFT, more uniform light can be given to the liquid crystal display panel.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a backlight unit according to the present invention.

FIG. 2 is a plan view showing a straight tube type CCFT used in the embodiment.

FIG. 3 is a cross-sectional view showing the inside of a case in which a CCFT is stored in the embodiment.

FIG. 4 is a graph showing a luminance distribution of CCFT obtained in the above embodiment.

FIG. 5 is a plan view showing a first conventional example.

FIG. 6 is a sectional view showing a second conventional example.

[Explanation of symbols]

 2 Straight tube type CCFT 21, 22 Electrode terminal 10 Case 11 Through hole 12 Guide plate 121 Main insertion part 122 Sub insertion part 50 Elbow cap 61, 62 Lead wire

Claims (3)

[Claims] 1. A liquid crystal for irradiating light from a cold-cathode fluorescent tube (CCFT) to a rear side of a liquid crystal display panel by housing a straight tube-type cold-cathode fluorescent tube (CCFT) in a case having an open upper surface. In the backlight unit for a display device, the first lead connected to one of the electrode terminals of the first and second lead wires connected to each electrode terminal provided at both ends of the cold cathode fluorescent tube. A wire is wired along the cold cathode fluorescent tube toward the other electrode terminal side,
A backlight unit for a liquid crystal display device, wherein the first and second lead wires are both drawn out of the case from the other electrode terminal side. 2. The backlight unit for a liquid crystal display device according to claim 1, wherein the first lead wire is wired just above the cold cathode fluorescent tube. 3. A guide plate having an insertion hole formed by serially forming a sub-insertion portion for the first lead wire above a main insertion portion for the cold-cathode fluorescent tube in the case. The backlight unit for a liquid crystal display device according to claim 1 or 2, wherein