Patent Application
20080094325
The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
Reference now should be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components.
Before the technical concept applied to the present invention is described, the procedure in which static electricity is introduced into an LCD module and systematic errors occur due to the static electricity is described with reference to
Since the panel guide 3 for fastening an LCD panel and a hole for fastening the TCP board illustrated in the accompanying
It is apparent that the metal pattern around the hole for fastening the board does not contact the metal patterns within the TCP board, but, in view of the fact that the static electricity has characteristics of high-voltage noise and the electric metal patterns of the TCP board into which the static electricity is introduced are very close, the static electricity is substantially introduced into the electric metal circuit patterns of the TCP board though the metal pattern having the certain area around the hole for fastening the board.
Therefore, if the static electricity is introduced into the connections of a main board through the respective elements illustrated in
Therefore, if it is possible to drop the characteristic of the introduced static electricity from high voltage to low voltage, to convert instantaneous impact voltage into a signal having a predetermined time interval, and to conduct static electricity to a ground included in a circuit rather than en external ground, internal circuits can be protected from static electricity without use of the conventional metal casing or copper shield.
A preferred embodiment of the present invention is described below in detail with reference to the accompanying drawings.
The procedure of performing a static-electricity resistance function in the TCP board 60 which is applied to the LCD module according to the present invention constructed as described above is described. Static electricity is introduced through the hole FH for fastening the board as described above.
In this case, the static electricity having high-frequency components introduced through the hole FH for fastening the board is first introduced to the ground terminal within the TCP board 60 through the BC.
As a result, some of the frequency components are filtered out and attenuated through the bead core BC. At this time, 600 Ω(ohm)/100 MHz is selected from a range of 100 to 1,000 Ω(ohm)/100 MHz as the impedance of the bead core BC.
Thereafter, although the static electricity is conducted to the ground terminal within the TCP board 60, voltage which is higher than a predetermined value is introduced through respective elements within the TCP board. In this case, a problematic one of the cases where the static electricity leaks to the outside through the TCP board 60 is the case where the static electricity flows through the main board connection element 61 due to counter electromotive force.
The reason for this is that, since voltage flowing through the LCD panel has a high frequency when static electricity leaks through the LCD connection element 68, a small amount of screen flickering occurs even if a large amount of static electricity is introduced. In contrast, when static electricity leaks through the main board connection element, the shutdown or reset of a system occurs and, at worst, damage to a main board is caused. Furthermore, in view of the characteristic of electric current, the static electricity introduced into the TCP board 60 may be introduced both through the main board connection element 61 and the LCD connection element 68, but, because the resistance of the LCD panel is high, more static electricity is introduced into the main board element 61.
The static electricity introduced into the main board connection element 61 is introduced into a power supply terminal connected to the first resistance elements 62 and the fuse F, so that, in the present invention, the varistor V is provided to the output terminal of the fuse F.
The vasistor V for 5V is used because the power supply voltage of the panel is 3.3 V. Therefore, if static electricity occurs, the resistance value of the varistor V dramatically decreases, and thus a great deal of counter electromotive force is eliminated.
Furthermore, conventionally, a resistance element having an impedance of 22 Ω(ohm) is used as each of the first resistance elements 62, but, in the present invention, a resistance element having an impedance of 100˜200 Ω(ohm) is used as each of the first resistance elements 62.
Therefore, the magnitude of voltage introduced into the main board due to the counter electromotive force decreases.
Data about the results of between a safety solution to static electricity according to the present invention, a conventional method and several experimental groups, is listed in the following table.
Furthermore, the test method at this time is identical to the method illustrated in
In the table, the general LCD module means an LCD module in which no anti-static method is used, or, in a copper shielding method, a copper foil and a lead line are eliminated. Furthermore, the increase of a TCP resistance value is a comparative example in the case where the input resistor of the conventional TCP board of
As described above, there are advantages in that elements having high resistance to static electricity impact are used as circuit elements of a PCB inside a TCP connecting a front LCD panel to a rear main board, and static electricity introduced via the front LCD panel is dropped to a voltage that the main board can withstand when the static electricity is delivered to the main board, thereby having resistance to high voltage static electricity without requiring the formation or addition of a separate static electricity discharge path.
Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
