# US 4,393,432 A · Safety device for a conducting path in a load device

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 4,393,432 A
- Document ID: US4393432A
- Status: Granted
- Kind: A
- Application number: 06/123,150
- Filed: 1980-02-21
- Granted: 1983-07-12
- Earliest claimed: 1977-01-27
- Assignees: Robert Bosch GmbH
- Inventors: Dieter Neuhaus; Gerhard Sohner; Walter Ruf; Erich Jesse; Helmut Roth
- Web page: https://patentgrep.com/patent/US4393432A

## CPC

- H05K 10/00: Arrangements for improving the operating reliability of electronic equipment, e.g. by providing a similar standby unit
- H01H 85/046: Fuses formed as printed circuits
- H01H 85/463: {with printed circuit fuse}
- H05K 1/0293: {Individual printed conductors which are adapted for modification, e.g. fusable or breakable conductors, printed switches}
- H05K 1/18: structurally associated with non-printed electric components (H05K1/16 takes precedence)
- H05K 2201/09727: Varying width along a single conductor; Conductors or pads having different widths
- H05K 2201/10181: Fuse
- H05K 2203/168: Wrong mounting prevention
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00)

## Abstract

A safety device is included in a circuit comprising a power source and a user device. The power source has one terminal connected to ground, as does the user device, with the safety device connected in a conducting path leading to the ground in the user device. In the event of an incorrect polarity connection between the power source and user device, a current path through the safety device and to ground is established.

## Claims

### Claim 1

In combination with a user device and a current supply device, each device having at least two terminal connections and a ground connection, one of the terminal connections of the current supply device being connected to its ground connection, one of the terminal connections of the user device being connected to its ground connection, the other terminal connection of the user device being connected to a load element in the user device, a diode means in series with said load element between said other terminal of said user device and said load element; said load element also being connected to the ground connected terminal connection, of the user device said two terminal connections of both devices being engageable to produce a current flow, and a safety device within the user device connected between the ground connected terminal connection of the user device and the ground connection of the user device whereby during correct polarization of said user device, no current flows through said safety device, and during incorrect polarization of said user device said safety device operates to isolate said user device ground connection from said ground connected terminal connection.

### Claim 2 (depends on 1)

The combination as defined in claim 1, wherein the user device includes a housing to which the user device ground connection is connected.

### Claim 3 (depends on 1)

The combination as defined in claim 1, wherein the safety device is formed as part of a printed circuit board including a conducting path.

### Claim 4 (depends on 3)

The combination as defined in claim 3, wherein the safety device is formed as a decreased cross section of the conducting path.

### Claim 5 (depends on 3)

The combination as defined in claim 3, wherein the safety device is formed as a decreased cross sectional portion of the conducting path of a thick layer circuit.

### Claim 6 (depends on 3)

The combination as define in claim 3, wherein the safety device is formed as a decreased cross sectional portion of the conducting path of a thin layer circuit.

### Claim 7 (depends on 1)

The combination as defined in claim 1, wherein the user device includes a thick layer circuit board, and wherein the safety device is formed as part of the thick layer circuit board.

### Claim 8 (depends on 1)

The combination as defined in claim 1, wherein the user device includes a thin layer circuit board, and wherein the safety device is formed as part of the thin layer circuit board.