JPH11249111A - Liquid crystal display device and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the characteristics of an inductor mounted on a printed circuit board especially in the case of thinning. SOLUTION: Concerning a liquid crystal display device provided with a liquid crystal display panel 10, a printed circuit board 40 and frames 31, 32 and 33 for protecting the liquid crystal display panel 40 and the printed circuit board 40 and regulating electromagnetic waves radiated from the printed circuit board 40, an inductor 43b having no magnetic core is mounted on the printed circuit board 40 so that the winding plane of a coil can be almost parallel to the frame 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a liquid crystal display device having stabilized characteristics of an inductor mounted on a printed circuit board, and an electronic apparatus using the liquid crystal display device.

[0002]

2. Description of the Related Art A liquid crystal display device is composed of a liquid crystal display panel in which a liquid crystal material is sealed in a substrate such as glass, but is very weak against external stress by itself. Therefore, it is necessary to protect the liquid crystal display panel from impact or the like.

In a liquid crystal display device, it is necessary to input a power supply voltage, a clock signal, a video signal, and the like, and to appropriately generate a control signal and the like necessary for driving each pixel. A circuit board different from a driving circuit for driving, or a circuit board on which this driving circuit is also mounted is provided. At this time, it is necessary to appropriately prevent noise from entering the circuit board and radiation of electromagnetic waves from the circuit board.

[0004] Therefore, the liquid crystal display device is generally used in a state where the liquid crystal display panel and the circuit board are casing with a frame made of a conductive magnetic material such as iron.

On the circuit board, a PLL (Phase Locked Loop) for a local oscillator or a synchronous circuit is provided.
The oscillation frequency is set by combining values of an inductor mounted on a circuit board, a capacitor, a resistor, and the like. On the other hand, recently, the demand for a thinner liquid crystal display device has been extremely increasing.

[0006]

In order to reduce the thickness of the liquid crystal display device, the distance between the circuit board and the frame must be reduced as much as possible. For this reason, the inductor mounted on the circuit board and the frame as the conductive magnetic material are in a state of being very close to each other. Here, the conventional inductor 43a
As shown in FIG. 4, the winding surface of the coil is in a direction perpendicular to the printed circuit board 40, and therefore also in a direction perpendicular to the frame 32 which is a conductive magnetic material. Therefore, the magnetic flux passing through the coil changes due to the approach of the frame 32, and the inductance of the inductor 43a fluctuates easily. As a result, the frequency characteristics of the PLL are adversely affected, and the operation of the liquid crystal display device is likely to be unstable. was there.

The present invention has been made in view of such circumstances, and an object of the present invention is to stabilize the characteristics of an inductor mounted on a printed circuit board even when the inductor is thinned. It is an object of the present invention to provide a liquid crystal display device capable of performing the above, and an electronic device using the liquid crystal display device.

[0008]

According to the present invention, there is provided a liquid crystal display panel, a circuit board for driving and controlling the liquid crystal display panel, and protection of the liquid crystal display panel and the circuit board. And a frame that regulates electromagnetic waves radiated from the circuit board, wherein the inductor having no magnetic core is arranged such that the winding surface of the coil is substantially parallel to the frame. It is characterized in that it is mounted on the circuit board.

According to the present invention, the coil having no magnetic core is mounted on the circuit board such that the winding surface thereof is substantially parallel to the frame, so that the coil and the frame are extremely close to each other. Also, the magnetic flux penetrating the coil is hard to change,
For this reason, the characteristics of the inductor hardly fluctuate. Therefore, the operation of the liquid crystal display device can be stabilized.

Further, as the electronic equipment to which the liquid crystal display device according to the present invention is applied, for example, a car navigation system, a portable information terminal equipment, and other various electronic equipments can be considered.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1A is a schematic end view showing the structure of the liquid crystal display device according to the present embodiment.

As shown in FIG. 1, the liquid crystal display panel 10
Has a structure in which an element substrate 11 and a counter substrate 12 are bonded to each other, and a fluorescent tube 21, a light guide plate 22,
A backlight unit 20 including a diffusion plate 23, a reflection plate 24, and the like is provided. The backlight unit 2
In the case of 0, the fluorescent tube 21 is disposed on the side surface and the diffusion plate 23 is provided to make the light intensity uniform so as to realize a uniform surface light source with a thin structure.

Here, the liquid crystal display panel 10 has pixels arranged in a matrix, and these pixels are driven by a simple matrix type, an active matrix type, or the like, and the pixels from the backlight unit 20 are transmitted. By controlling the amount of light transmission, desired display is performed.
Further, the liquid crystal display panel 10 is housed in the frame 31,
The backlight unit 20 is fixed on a frame 32.

Next, the printed circuit board 40 receives a power supply voltage, a clock signal, a video signal, and the like, and supplies a drive control signal such as a power supply, a data signal, and a control signal to the drive circuit of the liquid crystal display panel 10. Therefore, in the figure, components 4 such as IC, resistor, inductor, etc.
1 is implemented. Although a drive circuit of the liquid crystal display panel 10 is not shown, a COG (Chip On Gras
s) and TAB (Tape Automated Bonding).

The printed circuit board 40 is fixed in a frame 33, and an insulating sheet 45 is laid so that a circuit pattern, a mounted component 41 and the like do not make electrical contact with the frames 32 and 33. This insulating sheet can be omitted as long as the space between the terminal of the mounting component and the frame is ensured and the circuit pattern and the frame are not in electrical contact.

Here, each of the frames 31 to 33 protects the liquid crystal display panel 10, the backlight unit 20, the printed circuit board 50, and the like from shocks and noises and the like.
It plays a role in regulating electromagnetic waves radiated from. Therefore, each frame is made of a conductive magnetic material such as iron.

The frames 31 to 33 are electrically connected to each other in the region 50 and are grounded.

As described above, in order to reduce the size and thickness of the liquid crystal display device, it is desirable that the distance between the frame 32 and the printed circuit board 50 be as short as possible.

On the other hand, the oscillation frequency of the PLL mounted on the printed circuit board 50 may be set using an inductor.

In such a case, as shown in FIG. 4, the use of an inductor 43a whose winding surface is perpendicular to the printed circuit board 40 adversely affects the frequency characteristics of the PLL, resulting in a liquid crystal display device. The reason why the operation is likely to be unstable is as described above.

Therefore, in the present embodiment, as shown in FIG. 1B (the insulating sheet 45 is not shown), an inductor 43b whose winding surface is parallel to the printed circuit board 40 is used. Thereby, the winding surface of the coil is
Since the direction is parallel to the frame 32, the magnetic flux penetrating the coil hardly changes even when the frame 32 approaches. Therefore, since the frequency characteristics of the PLL are hardly affected, the operation of the liquid crystal display device is stabilized.

It should be noted that there is a type of inductor whose coil winding surface is parallel to the printed circuit board 40, which has a screw-in type magnetic core and whose inductance is variable. However, in such an inductor, after the printed circuit board 50 is incorporated in the frame, it is necessary to finely adjust the magnetic core position of the inductor disposed in the frame 32 from the outside. The hole must be opened, which requires an extra step. Furthermore, if there is an opening in the frame 32,
There is no magnetic material in that part. Therefore, an inductor having a magnetic core essentially does not have the problem of the present invention.

The liquid crystal display device according to the embodiment has a backlight unit 20 because it is a transmission type, but the backlight unit 20 may be omitted as a reflection type. As a result, it is possible to further reduce power consumption and reduce the size, weight, and thickness.

In the present embodiment, the circuit board 4
0 is fixed to the frame 33 side and the mounting surface of the electronic component such as the inductor is on the frame 32 side. However, the circuit board 4 may be fixed on the frame 32 side and the mounting surface may be on the frame 33 side.

<Electronic Equipment: Part 1> Next, some examples in which such a liquid crystal display device is used in electronic equipment will be described.

First, an example in which the liquid crystal display device is applied to a personal computer will be described. FIG. 2 is a front view showing the configuration of the personal computer. In the figure, a personal computer 1200 includes a main body 1204 having a keyboard 1202 and a liquid crystal display device 12.
06. This liquid crystal display device 1206
Are the liquid crystal display panel 10 and the backlight 20 described above.
It is composed of

<Electronic Equipment: Part 2> Next, an example in which a liquid crystal display panel is applied to a pager will be described. FIG.
FIG. 2 is an exploded perspective view showing the structure of the pager. As shown in this figure, the pager 1300 includes a metal frame 130
2, the liquid crystal display panel 10 is
Light guide 1306 including 06a, circuit board 130
8, the first and second shield plates 1310 and 1312 are housed together. The liquid crystal display panel 10 and the circuit board 10 are electrically connected to each other by the two elastic conductors 1314 and 1316 for the counter substrate 32 and by the film tape 1318 for the element array substrate 30. .

In addition, other than the above, a liquid crystal television, a viewfinder type, a monitor direct-view type video tape recorder,
Car navigation devices, electronic organizers, calculators, word processors, workstations, mobile phones, video phones,
Examples of the electronic device include a POS terminal, a device including a touch panel, and the like. It goes without saying that the present invention can be applied to these various electronic devices.

[0030]

As described above, according to the present invention,
Since the coil without magnetic core was mounted on the circuit board so that the winding surface was in a direction substantially parallel to the frame,
Even if the coil and the frame are extremely close to each other, the magnetic flux penetrating through the coil hardly changes, and therefore, the characteristics of the inductor hardly change. Therefore, the operation of the liquid crystal display device can be stabilized.

[Brief description of the drawings]

FIG. 1A is an end view showing a schematic configuration of a liquid crystal display device according to an embodiment of the present invention, and FIG. 1B is a diagram showing a positional relationship among an inductor, a printed circuit board, and a frame. .

FIG. 2 is a front view illustrating a configuration of a personal computer as an example of an electronic apparatus to which the liquid crystal display device is applied.

FIG. 3 is an exploded perspective view showing a configuration of a pager as an example of an electronic apparatus to which the liquid crystal display device is applied.

FIG. 4 is a diagram showing a configuration of a conventional inductor.

[Explanation of symbols]

 10 liquid crystal display panel, 20 backlight, 40 printed circuit board (circuit board), 31, 32, 33 frame 43b inductor

Claims (2)

[Claims] 1. A liquid crystal display panel, a circuit board for driving and controlling the liquid crystal display panel, and a frame for protecting the liquid crystal display panel and the circuit board and for regulating electromagnetic waves radiated from the circuit board. A liquid crystal display device comprising: an inductor having no magnetic core mounted on the circuit board such that a winding surface of the coil is substantially parallel to the frame. 2. An electronic apparatus comprising the liquid crystal display device according to claim 1.