JP2535035Y2 - Surge current bypass device in electronic circuit board - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a surge current bypass device for an electronic circuit board, and particularly to an electronic circuit board provided with a balun transformer such as an electronic tuner. The present invention relates to a surge current bypass device in an electronic circuit board which prevents a circuit element from being deteriorated or damaged by a surge voltage applied to a balanced input section.

[Prior Art] Conventionally, an electronic circuit board provided with a balanced input section such as a 300Ω antenna connector is provided with a balanced-unbalanced transformer and converts a balanced input into unbalanced and connected to a circuit. No measures have been taken to prevent surge current such as static electricity applied through the unit.

[Problem to be Solved by the Invention] In the above-described conventional electronic circuit board, when a human body or the like comes into contact with the contact of the balanced input unit and the charged static electricity is applied to the human body, the balanced input unit is Since it is not grounded, it discharges to circuit elements such as capacitors exposed on the circuit pattern near the balanced input section. Therefore, a surge current flows to the circuit element, which has an adverse effect such as deteriorating or destroying the performance.

Therefore, a technical problem to be solved in order to prevent the discharge of the balanced input section and the circuit element, to eliminate the adverse effect of the surge current, and to improve the reliability of the electronic circuit board arises. The idea is to solve the problem.

[Means for Solving the Problems] The present invention has been proposed to achieve the above object, and a balun is provided on one side of a circuit board.
The balanced input section of the balun transformer includes a coil, and the unbalanced circuit is configured such that a signal is input from the coil of the balanced input section to an unbalanced circuit by inductive coupling. An electronic device in which a ground pattern is arranged between a circuit element of a circuit and a coil of a balanced input section to form a discharge section, and a surge voltage flying from the balanced input section to the air is absorbed by the discharge section. It is an object to provide a surge current bypass device in a circuit board.

[Operation] In the present invention, a ground pattern is arranged between a coil of a balanced input portion of a balun transformer provided on one side of an electronic circuit board and a circuit element of a circuit pattern of an unbalanced circuit facing the coil. And a discharge section. Therefore, when a surge voltage is applied to the balanced input section, the current is discharged from the coil of the balanced input section to a nearby discharge section, bypassed to the chassis, and the surge current flows to the circuit element on the board. Absent.

Embodiment An embodiment of the present invention will be described below in detail with reference to FIGS. 1 and 2 of the accompanying drawings. For convenience of explanation, technical matters belonging to the related art will be described at the same time.

FIG. 1 is a plan view of an electronic tuner (1) for receiving a VHF / UHF broadcast, the electronic tuner (1) being a chassis (2).
And an electronic circuit board (3). On one side of the chassis (2), terminals (4) (4)... For IF signal output and power input are arranged, and on the front side (left in the figure).
A balanced input section (5) for a UHF antenna and an unbalanced input section (6) for a VHF antenna protrude.

A contact (7) is provided at the rear of the balanced input section (5).
(7) A coil (8) for connecting the rear end portion is wound, and the coil (8) and the inductor element (9) disposed on the electronic circuit board (3) so as to face the coil (8). ) Etc. from 300
A balanced-unbalanced transformer (10) for converting a Ω balanced input to a 75Ω unbalanced output is formed.

The electronic circuit board (3) is disposed below the balanced input section (5), and has a + pattern (11) and a ground pattern (12) of an unbalanced circuit on the back as shown in the bottom view of FIG.
Is printed, and the solder resist (14) is coated on the entire surface except for the lands (13) (13) for soldering. or,
The ground pattern (12) is disposed on the side edge of the substrate,
The inner surface of the chassis (2) is grounded by solder (S), and a ground pattern (12) is extended along the front edge of the substrate facing the coil (8). Then, the solder resist is removed to expose the copper foil to form a discharge part (15). The discharge part (15) may be plated with solder or the like to prevent oxidation of the copper foil.

Thus, the contact (7) of the balanced input section (5)
For example, when a human body or the like comes into contact with (7) and static electricity charged on the human body is applied, the static electricity is applied to the discharge unit (1) closest to the coil (8) because the balanced input unit (5) is not grounded.
Discharge to 5) and bypass to chassis (2) via ground pattern (12). Accordingly, no discharge is caused from the coil (8) to the chip capacitor (16) of the unbalanced circuit, and the circuit elements such as the chip capacitor (16) are prevented from being broken or the performance is deteriorated.

The present invention can be variously modified without departing from the spirit of the present invention, and it is natural that the present invention extends to the modified one.

[Effects of the Invention] The present invention is designed such that when a signal is input from a coil of a balanced input section to an unbalanced circuit provided on a circuit board by inductive coupling, a ground is provided between the coil of the balanced input section and the unbalanced circuit. A pattern is provided, and a discharge unit for absorbing a surge voltage flying from the coil of the balanced input unit to the air is provided on the ground pattern. The flying surge voltage is discharged to the discharge portion and bypassed to the chassis, so that the surge voltage is not applied to the circuit element of the unbalanced circuit mounted on the circuit board, Therefore, circuit elements such as capacitors may deteriorate,
Or it will not be destroyed.

That is, when a signal is input from the coil of the balanced input section to the balun transformer by inductive coupling, the surge voltage flying from the coil to the air does not flow to the circuit elements on the circuit board, and various voltages due to the surge voltage are generated. Can be prevented beforehand.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, FIG. 1 is a partially cutaway plan view of an electronic tuner, and FIG. 2 is a cutaway bottom view of the same part. (3) ... electronic circuit board, (5) ... balanced input section (8) ... coil (10) ... balanced unbalanced transformer (11) ... + pattern (12) ... ground pattern (15) …… Discharge part (16) …… Chip capacitor

Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H04B 1/18 H04N 5/44 K H04N 5/44 7/16 A 7/16 H01L 23/56 C (56) References Japanese Utility Model Sho-64-37340 (JP, U) Japanese Utility Model Sho-63-7936 (JP, U) Japanese Utility Model Sho-55-131086 (JP, U)

Claims (1)

(57) [Scope of request for utility model registration] 1. A balanced-unbalanced transformer is provided on one side of a circuit board, and a balanced input section of the balanced-unbalanced transformer comprises a coil, and the coil of the balanced input section is inductively coupled to an unbalanced circuit. In an electronic circuit board configured to receive a signal, a ground pattern is provided between a circuit element of the unbalanced circuit and a coil of a balanced input section to form a discharge section, and the balanced input A surge current bypass device in an electronic circuit board, wherein a surge voltage flying from a portion to the air is absorbed by the discharge portion.