JPH0964572A - Earth pattern for protecting against lightning and static electricity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the impedance by forming a closed loop earth pattern around an integrated circuit element among the devices mounted on a main printed board thereby increasing the area of earth pattern on the periphery of IC. SOLUTION: The metal case part 20 of a tuner, a power supply circuit 21, an IC 22, and the like are mounted on a main printed board 19. A loop earth pattern 24 surrounding the peripheral part 23 of IC 22 is formed on the main printed board 19, an earth pattern 25 is formed under the IC 22, and an earth pattern 26 is formed on the periphery of main printed board 19 and then the earth patterns 24, 25, 26 are interconnected. The metal case part 20 is connected with the earth pattern 26 which is coupled through a discharge gap 27 with the power supply circuit 21 being connected with an external AC power supply plug socket. This circuitry prevents erroneous function of electronic device and protects the electronic device against breakdown.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground pattern for protecting electronic equipment from lightning and static electricity.

[0002]

2. Description of the Related Art Conventionally, as is clear from the component layout diagram shown in FIG. 2, components of electronic equipment such as a television receiver are mainly arranged in a metal case portion 1 of a tuner, a main printed circuit board 2, a power supply circuit 3 and the like. The components are individually arranged on the metal chassis 4, and the metal case portion 1 of the tuner 1 and the main printed circuit board 2
The exposed metal parts of the main parts such as the upper ground pattern 5 are connected to the ground line 6 of the metal chassis 4 by the braided wire 7,
Discharge gap 9 from earth line 6 to AC power supply line 8
Had to be discharged through. Reference numeral 10 is a power input terminal on the main printed circuit board 2, and 11 is an AC power outlet.

In general, lightning and static electricity are likely to be applied to exposed metal parts such as a metal case of a tuner, an AV terminal (AV JACK), an outer case such as an antenna terminal, and such exposed metal parts are AC power supply lines. It discharges to the outside of the electronic device. In FIG. 2 showing the above-mentioned conventional example, the metal case portion 1 of the tuner and the earth pattern 5 on the main printed circuit board 2 are connected to the earth line 6 of the metal chassis 4, respectively. For example, the metal case portion 1 of the tuner is charged. The generated static electricity is directly discharged to the ground line 6 of the metal chassis 4 without passing through the ground pattern 5 on the main printed board 2, and finally discharged to the external AC power supply line 8.

Therefore, static electricity charged in the metal case portion 1 of the tuner may be discharged to the earth pattern 5 on the main printed circuit board 2 to cause malfunction of an integrated circuit element (hereinafter referred to as IC) on the main printed circuit board 2. Almost never.

However, in the recent parts arrangement of electronic equipment such as a television receiver, all the main parts from the electronic parts such as ICs, resistors, capacitors and coils to the tuner are arranged on the main printed circuit board. All exposed metal parts such as the metal case of the tuner arranged on the main printed circuit board are connected to the ground pattern on the main printed circuit board. The routing becomes more diverse,
The exposed metal part to which lightning and static electricity are applied and the part of the ground pattern connected to it and the part far from the ground pattern may have different potentials, and discharge between the ground patterns will also occur. It was not possible to prevent the electronic parts connected to the ground pattern from being damaged by lightning and electrostatic potential difference by simply discharging the AC power line through the ground pattern.

Further, conventionally, in order to prevent static electricity from entering the IC, the impedance of the ground pattern is made small so that the area of the ground pattern is made as large as possible. In order to increase the area of the ground pattern, specifically, as shown in the component layout diagram of the electronic device of FIG. 3, the ground pattern 14 is also provided on the lower surface of the IC 13 provided on the main printed circuit board 12. Then, the impedance of the ground pattern 14 in the peripheral portion of the IC 13 is reduced, and discharge is generated between the other ground pattern 16 input from the line 15 which is at a high potential due to lightning, static electricity, etc. and the ground pattern 14. Even so, the potential is prevented from instantaneously varying depending on the position in the ground pattern 14. However, due to the discharge between the earth patterns 14 and 16,
It was difficult to completely prevent a potential difference from occurring between the respective positions in the ground pattern 14 which should have the same potential. That is, the IC signal terminal 17 which has a high potential and I
The IC 13 may malfunction due to the potential difference between the ground pattern 14 on the lower surface of C13. Reference numeral 18 is a ground terminal of the IC 13 connected to the ground pattern 14. Further, in order to prevent a potential difference from occurring between the earth patterns 14 and 16, only common measures (printed board technical standard, design standard, etc.) such as maintaining the distance between the earth patterns 14 and 16 for a predetermined distance or more. The malfunction of the IC due to static electricity such as lightning has not completely disappeared, and it is necessary to take separate measures separately. For each chassis, a lightning test or the like is performed and cut and try measures are taken.

[0007]

The lightning and electrostatic protection earth pattern of the present invention is applicable to all types of electronic components such as ICs, resistors, capacitors and coils on the main printed circuit board to the tuner. In recent electronic devices with main components installed, the wiring of the ground pattern is diversified in order to connect the exposed metal parts of all the main components to the ground pattern on the main printed circuit board, and lightning and static electricity are generated. Solved the problem that electronic parts such as IC may malfunction or be destroyed due to discharge between the ground patterns caused by different potentials of the ground pattern part connected to the exposed exposed metal part and the distant part of the ground pattern. To do.

[0008]

In order to solve the above problems, the present invention is an electronic device in which an exposed metal portion of a component arranged on a main printed circuit board is connected to a ground pattern on the main printed circuit board. In, in the parts arranged on the main printed circuit board, by forming a closed-loop ground pattern around the IC, the area of the ground pattern around the IC is increased as much as possible to reduce the impedance of the ground pattern. It is a ground pattern for protection against lightning and static electricity that is made small so that the potential does not change depending on the position of the ground pattern.

[0009]

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

FIG. 1 shows a lightning according to an embodiment of the present invention.
FIG. 9 is a component layout diagram of an electronic device using an electrostatic protection ground pattern, in which components such as a metal case portion 20 of a tuner, a power supply circuit 21, an IC 22 are arranged on a main printed circuit board 19, and the main printed circuit board 19 is also provided. In the above, a loop-shaped ground pattern 24 is formed so as to surround the peripheral portion 23 of the IC 22, a ground pattern 25 is formed below the IC 22, and a ground pattern 26 is formed in the peripheral portion of the main printed circuit board 19.
25 and 26 are connected to each other. Further, the metal case portion 20 of the tuner, which is an exposed metal portion, is connected to the earth pattern 26, and the earth pattern 26 is connected to the discharge gap 2
7 to the power supply circuit 21 and further to the power supply circuit 2
1 to the external AC power outlet 28.

In the above structure, static electricity charged on the exposed metal portion of the metal case portion 20 of the tuner is generated by the IC2.
Since the AC power is discharged through the same earth line as the electronic parts such as 2, the earth pattern 24,
Discharge may occur between 25 and 26, but IC2
Loop-shaped ground pattern 2 surrounding the peripheral portion 23 of 2
4, the IC22 by the ground pattern 25 under the IC22
Since the impedance of the ground pattern in the peripheral portion is small, the potential does not momentarily change depending on the position of the ground pattern, and malfunction or destruction of the IC 22 does not occur.

[0012]

As described above, according to the present invention, in an electronic device in which an exposed metal portion of a component arranged on a main printed circuit board is connected to a ground pattern on the main printed circuit board, By forming a closed-loop ground pattern around the IC in the installed components, the area of the ground pattern around the IC is increased, the impedance is reduced, and malfunctions and destruction of electronic components such as ICs are performed. Can be prevented.

[Brief description of drawings]

FIG. 1 is a component layout diagram of an electronic device using a ground pattern for protection against lightning and static electricity according to a first embodiment of the present invention.

FIG. 2 is a component layout diagram of a conventional electronic device.

FIG. 3 is a component layout diagram of a conventional electronic device

[Explanation of symbols]

 1,20 Tuner metal case part 2,12,19 Main printed circuit board 3,21 Power circuit 4 Metal chassis 5,14,16,25,26 Ground pattern 6 Ground line 7 Braided wire 8 AC power line 9,27 Discharge gap 10 Power Input Terminal 11, 28 AC Power Outlet 13,22 IC 15 Line 17 IC Signal Terminal 18 Ground Terminal 23 Peripheral Part 24 Looped Ground Pattern

Claims (1)

[Claims] 1. In an electronic device in which an exposed metal portion of a component arranged on a main printed circuit board is connected to a ground pattern on the main printed circuit board, an integrated circuit among the components arranged on the main printed circuit board. Ground pattern for protection against lightning and static electricity, which consists of a ground pattern formed in a closed loop around the element.