Burst length proportioning controller

Claim 2

A burst length proportioning controller for regulating the current flow from a voltage source to a condition-controlling load in a manner tending to maintain a condition controlled at a predetermined set point, said condition controller comprising the combination of a sensing means for producing a conditionresponsive DC signal which varies in magnitude from a nominal level substantially solely as a function of any deviation of said condition from its set point, reference means for supplying a reference signal which cyclically varies in magnitude between upper and lower values independently of said condition-responsive signal, a regenerative bistable circuit means which has one input coupled to receive said condition-responsive signal and another input coupled to receive said reference signal to supply an output signal when the magnitude of a predetermined one of said signals exceeds the magnitude of the other of said signals, and a switch means connected between said source and said load and coupled to said bistable circuit means for operation in response to said output signal to complete a circuit for current flow between said source and said load, whereby said load is then energized to return said condition to its set point.

Claim 3

The burst length proportioning controller of claim 1 wherein said source is an AC voltage source of predetermined frequency, and said switch means is a latching type; and further including means coupled between said bistable circuit means and said switch means and responsive to the amplitude of the voltage supplied by said source for gating output signals from said bistable circuit means to said switch means in timed synchronism with the zero crossings of the current from said source to thereby minimize the noise and interference generated by the operation of said switch means.

Claim 4

The burst length proportioning controller of claim 1 wherein said reference means is a sawtooth-generating means which supplies a sawtooth reference signal that cyclically varies in magnitude between predetermined upper and lower values which are respectively above and below the nominal level of said condition responsive signal.

Claim 5

The burst length proportioning controller of claim 3 wherein said source is an AC voltage source of predetermined frequency and said switch means is a bidirectional latching-type switch; and further including a gate means coupled between said bistable circuit means and said switch means, and a zero-crossing detector means coupled between said AC source and said gate means for inhibiting said gate means whenever the current supplied by said source is outside a zero-crossing region, whereby said switch means is operated only when there is an output signal from said bistable circuit means at the same time as the voltage of said source is in a zero-crossing region and is then effective to supply a substantially complete half-cycle of said curreNt to energize said load.

Claim 6

The burst length proportioning controller of claim 4 further including a full-wave rectifying means coupled to said AC source for supplying a pulsating DC potential with a ripple frequency twice the frequency of the AC voltage supplied by said source; and wherein said zero-crossing detector means comprises a breakdown diode having a predetermined breakdown threshold and a dropping resistor connected between said rectifying means and a point of reference potential, and said gate means has one input coupled to said bistable circuit means, another input coupled to a junction between said diode and said dropping resistor, and an output coupled to said switch means, said gate means being enabled when there is an output signal from said bistable circuit means and said DC potential is below the breakdown potential of said diode and then being effective to supply an output pulse of predetermined amplitude for triggering said switch means.

Claim 7

The burst length proportioning controller of claim 1 wherein said source is an AC voltage source of predetermined frequency, said switch means comprises a pair of controlled rectifiers with respective anode-cathode power circuits oppositely poled and connected in parallel between said AC source and said load and having respective gate-cathode firing circuits; and further including a full-wave rectifier means coupled to said AC source for supplying a pulsating DC potential with a frequency twice that of said AC current, a NOR gate means with an output coupled to the gate-cathode firing circuits of said controlled rectifiers, signal-inverting means coupled between said bistable means and a first input to said NOR gate means for applying a first inhibiting signal thereto in the absence of an output signal from said bistable circuit means, and a zero-crossing detector means coupled between said rectifier means and a second input to said NOR gate means for applying a second inhibiting signal thereto when said AC voltage is outside a zero-crossing region, whereby a firing pulse for said controlled rectifiers is produced only when there is an output signal from said bistable circuit means concurrently with the passage of said AC voltage through a zero-crossing region.

Claim 8

The burst length proportioning controller of claim 6 wherein said reference means is a sawtooth generator producing a sawtooth reference signal having a frequency which is substantially less than said predetermined frequency.

Claim 9

In a burst length proportioning controller for use with an AC voltage source, the combinatioN comprising a regenerative bistable circuit means having first and second inputs and means for producing an output signal having first and second logic levels respectively representative of the amplitude of the signal applied to said first input exceeding and being exceeded by the amplitude of the signal applied to said second input, means for applying to said one input a DC signal which varies in amplitude from a nominal level substantially solely as a function of deviations in a controlled condition from a predetermined set point, means for applying to the other of said inputs a repetitive sawtooth reference signal which independently varies between upper and lower limits above and below said nominal level whereby the duration of said output signal at said first and second logic levels varies as a function of the deviations of said controlled condition from its set point, detector means for sensing zero crossings of the AC voltage supplied by said source, and gate means coupled to said bistable means and to said detector means for providing a trigger pulse only when a zero crossing of said AC signal is detected coincidentally with said output signal being at a preselected one of said logic levels.

Claim 10

In a burst length proportioning controller for use with an AC voltage source, the combinatioN comprising a regenerative bistable circuit means having first and second inputs and means for producing an output signal having first and second logic levels respectively representative of the amplitude of the signal applied to said first input exceeding and being exceeded by the amplitude of the signal applied to said second input, means for applying to said one input a DC signal which varies in amplitude from a nominal level substantially solely as a function of deviations in a controlled condition from a predetermined set point, means for applying to the other of said inputs a repetitive sawtooth reference signal which independently varies between upper and lower limits above and below said nominal level whereby the duration of said output signal at said first and second logic levels varies as a function of the deviations of said controlled condition from its set point, detector means for sensing zero crossings of the AC voltage supplied by said source, and gate means coupled to said bistable means and to said detector means for providing a trigger pulse only when a zero crossing of said AC signal is detected coincidentally with said output signal being at a preselected one of said logic levels.

Claim 11

The combination of claim 8 wherein said output signal is at relatively high and low-logic levels when the amplitude of said DC signal respectively exceeds and is exceeded by the ampLitude of said reference signal, said gate means comprises a NOR gate having one input coupled to said detector means and another input coupled to said bistable means, said detector means includes means for applying an inhibiting signal to said gate whenever said AC signal is outside a zero-crossing region, and further including an inverting means between the bistable means and said gate whereby another inhibiting signal is applied to said gate whenever said output signal is at a high-logic level.