US 4,365,164 A · Vital contact isolation circuit

Abstract

A contact monitoring circuit for producing a dynamic signal representative of the state of a contact. The circuit includes a control signal generator for generating a pair of optical pulse streams comprised of alternate and sequential optical pulses. A pair of gating means, each responsive to one of the pair of pulse streams, connects each of two conductors to one of a positive and negative source of potential in time coincidence with the associated pulse stream. A circuit means, including an optical coupler, the contact being monitored and a fixed potential, has a complete supply circuit during times coincident with only one of the pulse streams, the condition of the contact determines which of the pulse streams will complete the supply circuit. Therefore, the optical coupler produces a dynamic signal representative of the contact state.

Claims14

Dependent claims

A coupling arrangement for coupling an indication of the state of a contact in the form of a dynamic signal without electrically connecting a representation of said dynamic signal to said contact or any circuit electrically connected thereto, said coupling arrangement comprising:

control means for generating two streams of alternate sequential control pulses,
a pair of control pulse responsive switches, each responsive to a different one of said stream of pulses,
a pair of conductors,
a pair of gating means each responsive to a different one of said switches for connecting one of said two conductors to one of two different potential sources in time coincidence with said two streams of optical pulses,
circuit means, including said contact and connected to said two different conductors, including isolator means for energizing an output of said isolator means in coincidence with one or another of said control pulse streams depending on the condition of said contact,
whereby when said contact is in one state, said output of said isolator means is energized coincident with one stream of said pulses, and when said contact is in another state, said output of said isolator means is energized coincident with said other of said pulse stream.

3 more elements

A dynamic contact check circuit for monitoring the state of a contact which, in one state is at a given potential, and in the other state is not at said given potential comprising:

optical signal generator means for generating a first optical pulse stream and a second optical pulse stream complementary to said first optical pulse stream,
first and second optically responsive switches responsive, respectively to said first and second optical pulse stream,
first and second conductors,
first and second gating means responsive, respectively, to said first and second switches and connected respectively between a first potential and said first conductor and a second potential and said second conductor, for connecting said conductors to said associated potentials in coincidence with said associated pulse streams,
circuit means connected to said conductors and said contact and including an optical pulse generator for completing a current supply circuit through said optical pulse generator in coincidence with said first or second optical pulses depending on whether said contact is or is not at said given potential,
and an output circuit with an optically responsive switch which is or is not closed depending on whether or not current flows in said optical pulse generator,
whereby said optically responsive switch is energized in coincidence with said first or second optical pulse stream depending on whether said contact is or is not at said given potential.

4 more elements

Dependencies are inferred from the claim text.

Vital contact isolation circuit

Life of this patent

Vital contact isolation circuit

Life of this patent

Abstract

Claims14