Electronic products with improved surge protecting circuit

• US 5,892,669 A
• Filed: 11/26/1997
• Issued: 04/06/1999
• Est. Priority Date: 11/29/1996
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Shin, Ki-Ho
• Primary Examiner(s): Hecker, Stuart N.
• Application Number:
  US08/978,950
• Time in Patent Office: 496 Days
• Field of Search: 363/34, 363/50, 361/40, 361/56, 361/111, 361/119, 361/120, 361/126, 361/138
• US Class Current: 363/50
• CPC Class Codes: H01Q 1/50 Structural association of antennas with earthing switches, lead-in devices or lightning protectors
• CPC Class Codes: H02H 7/12 for static converters or rectifiers for discharge lamp power supplies using static converters H05B41/2851, H05B41/2921, H05B41/2981
• CPC Class Codes: H02H 9/06 using spark-gap arresters

Abstract

An improved surge protecting circuit which can protect the power source and the internal and external circuit elements of an electronic product by absorbing external surges through ground. The protecting circuit according to the present invention is connected between an AC input terminal and an AC ground pattern. The protecting circuit includes surge absorption patterns having an arc discharge gap of preferably 0.25 mm, which is less than a specified safety distance, which is typically 5 mm, so as to absorb the external surges transmitted through the terminal to the AC ground pattern and a varistor connected between the surge absorption patterns and the AC ground patterns.

Claims

1. An improved surge protection circuit for an electronic product, the circuit comprising:

an alternating current (AC) input circuit responsive to an AC power source, having an AC ground pattern associated therewith, the AC input circuit including;

(a) a rectifying circuit connected to said AC power source for rectifying AC power from said AC power source, said rectifying circuit being connected to said AC ground pattern;

(b) a switch regulating circuit responsive to said rectified AC power, said switch regulating circuit being connected to said AC ground pattern;

(c) a transformer having a primary winding and a secondary winding, said primary winding being connected to said regulating circuit for receiving said rectified power, said primary winding being connected to said AC ground pattern;

(d) a surge absorption pattern having a pair of terminals, said terminals of said surge absorption pattern being separated by an arc discharge gap which is smaller than a safety distance, one of said terminals of said surge absorption pattern being connected to an AC input terminal of said AC input circuit; and

(e) a varistor, said varistor being connected in series between one of said terminals of said surge absorption pattern and said AC ground pattern for isolating noise generated by said AC power source; and

a direct current (DC) operating circuit being electromagnetically coupled to said AC input circuit through said transformer and having a DC ground pattern associated therewith which is separated from said AC ground pattern by said safety distance or more, the DC operating circuit including;

(a) a DC circuit, said DC circuit receiving power from said secondary winding of said transformer, said DC circuit and said secondary winding being connected to said DC ground pattern; and

(b) a terminal to which external surges are transmitted, said terminal being connected to said DC circuit, whereby external surges received by said terminal of said DC circuit are transmitted through said DC operating circuit to said AC input circuit through said transformer to said AC ground pattern wherein the external surge is then absorbed by an arc discharge in said arc discharge gap of said surge absorption patterns.

2. The improved surge protecting circuit as claimed in claim 1, wherein said arc discharge gap of said surge absorption patterns is about 0.25 mm.

3. In an electric device having an AC input circuit with an AC ground pattern associated therewith and AC input terminals for receiving commercial AC power, and a DC operating circuit with a DC ground pattern associated therewith and having a terminal for receiving external electrical surges, said device having a surge protection circuit which comprises:

a surge absorption pattern having a pair of terminals, said terminals of said surge absorption pattern being separated by an arc discharge gap which is smaller than a safety distance, wherein one of said terminals of said surge absorption pattern being connected to one of said AC input terminals of said AC input circuit; and

a varistor, said varistor being connected in series between one of said terminals of said surge absorption pattern and said AC ground pattern for isolating noise generated by said AC power from said DC operating circuit;

whereby external surges received by said terminal of said DC operating circuit are transmitted through said DC operating circuit to said AC input circuit through a transformer to said AC ground pattern wherein the external surge is then absorbed by an arc discharge in said arc discharge gap of said surge absorption patterns.

4. The improved surge protecting circuit as claimed in claim 3, wherein said arc gap of said surge absorption patterns is about 0.25 mm.