Device for testing the continuity of an electrical network deposited on a glass sheet

• US 3,911,357 A
• Filed: 03/04/1974
• Issued: 10/07/1975
• Est. Priority Date: 03/13/1973
• Status: Expired due to Term

• Current Assignee: Amos Adam
• Original Assignee: Amos Adam
• Inventors: Adam, Amos
• Primary Examiner(s): Strecker, Gerard R.
• Application Number:
  US05/448,044
• Time in Patent Office: 582 Days
• Field of Search: 324/51,52
• US Class Current: 324/505
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: G01R 31/54 Testing for continuity
• CPC Class Codes: H05B 1/0236 for vehicles
• CPC Class Codes: H05B 2203/017 Manufacturing methods or apparatus for heaters
• CPC Class Codes: H05B 2203/035 Electrical circuits used in resistive heating apparatus
• CPC Class Codes: H05B 3/84 Heating arrangements specially adapted for transparent or reflecting areas, e.g. for demisting or de-icing windows, mirrors or vehicle windshields

Abstract

A set of resistive strips each divided into two portions by a test point is connected to two terminals and constitutes a network to be tested for electrical continuity. The end terminals of two current sources mounted in series are connected to the network terminals, the junction point of the two sources is connected to one terminal of a detector and the other terminal is connected to a test point of one resistive strip. A flow of current through the detector indicates a discontinuity within one portion of the corresponding resistive strip.

Claims

1. A device for testing the continuity of a two-terminal electrical network deposited on a glass sheet and comprising at least two resistive strips connected in parallel to each other and in series between the terminals of said network and each having at least one accessible test point which divides said strips into two portions having ohmic values which are in a ratio K relative to each other, said device comprising at least one detecting system, wherein said device comprises a frame for holding the glass sheet on which the electrical network is deposited, two end terminals connected to end terminals of two direct current sources in series and one intermediate supply terminal connected to the intermediate terminal between said sources, said sources having electromotive forces in said ratio K relative to each other, detachable connecting means between each end supply terminal and the terminals of the network, a feeler for establishing an electrical contact between the test point of one resistive strip of said network and said detecting system, which is connected on the one hand to said feeler and on the other hand to said intermediate supply terminal, a fourth supply terminal connected to one end of an auxiliary current source whilst the other end of said source is connected to said intermediate supply terminal, and means for connecting said fourth supply terminal to said feeler.

2. A device according to claim 1, wherein said device comprises two resistors mounted in series between the end supply terminals, the junction point of said resistors being connected to the intermediate supply terminal and the ohmic values of said resistors being in a ratio of K relative to each other so as to constitute two current sources from a single current source which is connected to the end supply terminals.

3. A device for testing the continuity of a two-terminal electrical network deposited on a glass sheet and comprising at least two resistive strips connected in parallel to each other and in series between the terminals of said network and each having at least one accessible test point which divides said strips into two portions having ohmic values which are in a ratio K relative to each other, said device comprising at least one detecting system, wherein said device comprises a frame for holding the glass sheet on which the electrical network is deposited, two end terminals connected to end terminals of two direct current sources in series and one intermediate supply terminal connected to the intermediate terminal between said sources, said sources having electromotive forces in said ratio K relative to each other, detachable connecting means between each end supply terminal and the terminals of the network, a feeler for establishing an electrical contact between the test point of one resistive strip of said network and said detecting system, which is connected on the one hand to said feeler and on the other hand to said intermediate supply terminal, and detecting systems which are equal in number to the resistive strips of the network, each detecting system being connected on the one hand to said intermediate supply terminal and on the other hand to a said feeler, each feeler comprising a plunger slidably mounted within a stationary cylinder and subjected to the action of an elastic restoring system, the plunger supporting at one end a bUndle of wires in contact with the network and at the other end a rod providing a connection with a said detecting system.

4. A device according to claim 3, wherein all the feelers are mounted in line on an insulating support, the spacing between the feelers being equal to the spacing between the resistive strips of the network and wherein the feeler support is fixed on said frame in order that the line of feelers should coincide with the line of test points of the resistive strips of said network when the glass sheet is applied on said frame.

5. A device according to claim 4 and comprising a fourth supply terminal to be connected to one end of an auxiliary current source whilst the other end of said source is connected to the intermediate supply terminal, and means for connecting said fourth supply terminal to all the feelers, wherein the plunger rod of each feeler is adapted to actuate a switch connected between said feeler and the fourth supply terminal, said switch being normally closed and being opened when the glass sheet is applied on said frame.

6. A device according to claim 5, wherein the switch associated with each feeler comprises a metallic strip secured to the feeler support and disposed along the line of feelers and a contact strip connected elastically to the plunger rod of the corresponding feeler.

7. A device according to claim 3, wherein said device comprises two resistors mounted in series between the end supply terminals, the junction point of said resistors being connected to the intermediate supply terminal and the ohmic values of said resistors being in a ratio of K relative to each other so as to constitute two current sources from a single current source which is connected to the end supply terminals.