Electronic interval timing device

Claim 2

An elapsed-time reminder circuit, comprising: (a) a pair of electrolytic timing cells, each having first and second operating states, said timing cells having a relatively low resistance in said first operating state and a relatively high resistance in said second operating state, said timing cells being configured and arranged so as to change state from said first operating state to said second operating state in response to the application thereto for a known time interval of a current having a first polarity, and further to change state from said second operating state to said first operating state in response to the application thereto of a current having a second polarity opposite to said first polarity; (b) means supplying a current of said first polarity to one of said timing cells when said one timing cell is in said first operating state; (c) electrical circuit means for detecting when said one timing cell changes state from said first operating state to said second operating state, including means generating an output signal upon detection thereof; (d) means operative simultaneously with said detecting means for applying a current of said second polarity to the other timing cell when said other timing cell is in said second operating state, and changing the state of said other timing cell to a first operating state such that said other timing cell has been changed to a first operating state when said one timing cell changes state from said first operating state to said second operating state; (e) indicator means responsive to said output signal for indicating to an operator when said one timing cell changes state from said first operating state to said second operating state and hence, when said known time interval has elapsed; and (f) means adapted to permit alternating reversal of said pair of timing cells, respectively, between a first connection in said detecting means and a second connection in said applying means.

Claim 3

An apparatus of claim 1, including means for varying said known time interval.

Claim 4

An apparatus of claim 1, wherein said means adapted to permit reversal of said timing means is adapted so as to permit simultaneous reversal of said timing cells between said first connection in said detecting means and said second connection in said applying means.

Claim 5

An apparatus of claim 1, wherein said alarm means includes means responsive to said output signal for providing a visual indication that said known time interval has elapsed.

Claim 6

An apparatus of claim 1, including means for preventing larger amplitude voltage spikes from affecting the operation of said applying means.

Claim 7

An apparatus of claim 5, wherein said preventing means include a zener diode which is connected in said applying means so that it is parallel with said other timing cell.

Claim 8

An apparatus of claim 1, wherein said detecting means includes first and second transistors connected in Darlington with said one timing cell being connected between the emitter and the base of said first transistor, and wherein the emitter-collector circuit of said second transistor is connected intermediate a source of energizing voltage and said alarm means.

Claim 9

An elapsed-time reminder circuit, comprising: (a) electrolytic timing means having first and second operating states, said timing means having a relatively low resistance in said first operating state and a relatively high resistance in said second operating state, said timing means being configured and arranged so as to change state from said first operating state to said second operating state in response to the application thereto for a known interval of a current having a first polarity and further operative to change state from said second operating state to said first operating state in a response to the application thereto of a current having a second polarity opposite to said first polarity; (b) means supplying a current of said first polarity to said timing means when said timing means is in said first operating state; (c) electrical circuit means for detecting when said timing means changes state from said first operating state to said second operating state, including means generating an output signal upon detection thereof; (d) means applying a current of said second polarity to said timing means when said timing means is in said second operating state, thereby changing the state of said timing means to said first operating state; (e) indicator means responsive to said output signal for indicating to an operator when said timing means changes state from said first operating state to said second operating state and hence, when said known time interval has elapsed; and (f) means adapted to permit alternate connection of said timing means in said detecting means when said timing means is in said first operating state and in said applying means when said timing means is in said second operating state.

Claim 10

An elapsed-time reminder circuit, comprising: (a) electrolytic timing means having first and second operating states, said timing means having a relatively low resistance in said first operating state and a relatively high resistance in said second operating state, said timing means being configured and arranged so as to change state from said first operating state to said second operating state in response to the application thereto for a known interval of a current having a first polarity and further operative to change state from said second operating state to said first operating state in a response to the application thereto of a current having a second polarity opposite to said first polarity; (b) means supplying a current of said first polarity to said timing means when said timing means is in said first operating state; (c) electrical circuit means for detecting when said timing means changes state from said first operating state to said second operating state, including means generating an output signal upon detection thereof; (d) means applying a current of said second polarity to said timing means when said timing means is in said second operating state, thereby changing the state of said timing means to said first operating state; (e) indicator means responsive to said output signal for indicating to an operator when said timing means changes state from said first operating state to said second operating state and hence, when said known time interval has elapsed; and (f) means adapted to permit alternate connection of said timing means in said detecting means when said timing means is in said first operating state and in said applying means when said timing means is in said second operating state.

Claim 11

An apparatus of claim 8, including means for varying said known time interval.

Claim 12

An apparatus of claim 9, wherein said alarm means includes means responsive to said output signal for providing a visual indicator that said known interval of time has elapsed.

Claim 13

The apparatus according to claim 9 and wherein said electrolytic timing means are a pair of solid coulometric cell means.

Claim 14

The apparatus according to claim 11 and in which said means for permitting alternative connection of said timing means comprises reversible connection for said pair of solid coulometric cell means.

Claim 15

The apparatus according to claim 11 and in which said means for permitting alternate connection of said timing means comprises circuit switching means for selectively applying currents of first and second polarity to said timing means.

Claim 16

An elapsed-time service indicator for installation in motor vehicles for indicating when servicing of the vehicle is required, comprising: (a) a pair of electrolytic timing cells, each having first and second operating states, said timing cells having a relatively low resistance in said first operating state and a relatively high resistance in said second operating state, said timing cells being configured and arranged so as to change state from said first operating state to said second operating state in response to the application thereto for a known time interval of a current having a first polarity, and further to change state from said second operating state to said first operating state in response to the application of a current having a second polarity opposite from said first polarity; (b) battery operated means located in the vehicle for supplying a current of said first polarity to one of said timing cells, when said one timing cell is in said first operating state, said supplying means thus operating substantially only when said motor vehicle is in operation; (c) electrical circuit means for detecting when said one timing cell changes state from said first operating state to said second operating state in response to application of the current of said first polarity thereto, said electrical circuit means including means generating an output signal upon detection that said one timing cell has changed state from said first operating state to said second operating state; (d) battery operated means operative simultaneously with said detecting means to apply a current of said second polarity to the other timing cell when said other timing cell is in said second operating state, thereby changing the state of the other timing cell to said first operating state over the time interval said one timing cell is in said first operating state such that said other timing cell is in said first operating state when said one timing cell changes state from said first operating state to said second operating state; (e) indicator means energized by said output signal for indicating to the operator of the motor vehicle when said one timing cell changes state from said first operating state to said second operating state and hence, when said known time interval has elapsed and servicing of the vehicle is required; and (f) means adapted to permit reversal of said pair of timing cells, respectively, between a first connection in said detecting means and a second connection in said applying means.

Claim 17

An elapsed-time service indicator for installation in motor vehicles for indicating when servicing of the vehicle is required, comprising: (a) a pair of electrolytic timing cells, each having first and second operating states, said timing cells having a relatively low resistance in said first operating state and a relatively high resistance in said second operating state, said timing cells being configured and arranged so as to change state from said first operating state to said second operating state in response to the application thereto for a known time interval of a current having a first polarity, and further to change state from said second operating state to said first operating state in response to the application of a current having a second polarity opposite from said first polarity; (b) battery operated means located in the vehicle for supplying a current of said first polarity to one of said timing cells, when said one timing cell is in said first operating state, said supplying means thus operating substantially only when said motor vehicle is in operation; (c) electrical circuit means for detecting when said one timing cell changes state from said first operating state to said second operating state in response to application of the current of said first polarity thereto, said electrical circuit means including means generating an output signal upon detection that said one timing cell has changed state from said first operating state to said second operating state; (d) battery operated means operative simultaneously with said detecting means to apply a current of said second polarity to the other timing cell when said other timing cell is in said second operating state, thereby changing the state of the other timing cell to said first operating state over the time interval said one timing cell is in said first operating state such that said other timing cell is in said first operating state when said one timing cell changes state from said first operating state to said second operating state; (e) indicator means energized by said output signal for indicating to the operator of the motor vehicle when said one timing cell changes state from said first operating state to said second operating state and hence, when said known time interval has elapsed and servicing of the vehicle is required; and (f) means adapted to permit reversal of said pair of timing cells, respectively, between a first connection in said detecting means and a second connection in said applying means.