Method and apparatus for controlling flash tube discharge

Claim 2

A circuit for firing a strobe light flash tube, comprising: electronic clock means for generating a first output pulse train having a modulated pulse width and a second output pulse train having said modulated pulse width, a transformer having a primary winding and a secondary winding having an electrical energy output, an FET switch connected between said electronic clock means and said transformer, said FET receiving said first output pulse train and producing a rapidly changing input current in said primary winding, firing capacitor storage means connected between said secondary winding and said flash tube for storing said electrical energy output by said secondary winding, pulse counter means connected to said electronic clock means for receiving said second output pulse train, said pulse counter means producing control pulses at selected intervals, and control means connected between said pulse counter means and said flash tube to receive said control pulses, said control means providing trigger pulses to said flash tube to enable said stored electrical energy to discharge through said flash tube.

Claim 3

The circuit of claim 1, further comprising: a resistive feedback circuit connected between said transformer and said electronic clock means for generating a modulation signal functionally related to said input current of said primary winding, and means connected between said feedback circuit and said electronic clock means for receiving said modulation signal and for modulating said first output pulse to a width effective to maintain said input current at a level less than a saturation current for said transformer.

Claim 4

The circuit of claim 1, further comprising: transient damping circuits of resistor, capacitor and diode combinations connected across both said primary winding and said secondary winding to reduce self-induced transient voltages in said primary and secondary windings.

Claim 5

The circuit of claim 1, further including: shutdown means connected between said control means and said electronic clock means and responsive to said control pulses for inhibiting generation of said first output pulse train for a selected interval after said discharge through said flash tube.

Claim 6

The circuit of claim 1, wherein said feedback circuit further includes: a photocell circuit for regulating said stored electrical energy as a function of ambient lighting.

Claim 7

The circuit of claim 1, wherein said pulse counter means further includes: a binary counter for producing pulses at an increased interval relative to said second output pulse train, and a decade counter connected to said binary counter, said decade counter having a plurality of selectable output states for deriving said control pulses from said increased interval pulses.

Claim 8

Strobe light firing circuit for triggering a flash tube, comprising: electronic clock means for generating a first output pulse train having a modulated pulse width and a second output pulse train having said modulated pulse width, a transformer having a primary winding and a secondary winding having an electrical energy output, an FET switch connected between said electronic clock means and said transformer, said FET receiving said first output pulse train and producing a rapidly changing input current in said primary winding, firing capacitor storage means connected between said secondary winding and said flash tube for storing said electrical energy output by said secondary winding, a first counter connected to said electronic clock means for receiving said second output pulse train and for providing increased interval pulses functionally related to said second output pulse train, a second counter connected to said first counter for receiving said increased interval pulses, said second counter having a plurality of selectable output states for producing control pulses, and control means connected between said second counter and said flash tube to receive said control pulses, said control means providing trigger pulses to said flash tube to enable said stored electrical energy to discharge through said flash tube.

Claim 9

Strobe light firing circuit for triggering a flash tube, comprising: electronic clock means for generating a first output pulse train having a modulated pulse width and a second output pulse train having said modulated pulse width, a transformer having a primary winding and a secondary winding having an electrical energy output, an FET switch connected between said electronic clock means and said transformer, said FET receiving said first output pulse train and producing a rapidly changing input current in said primary winding, firing capacitor storage means connected between said secondary winding and said flash tube for storing said electrical energy output by said secondary winding, a first counter connected to said electronic clock means for receiving said second output pulse train and for providing increased interval pulses functionally related to said second output pulse train, a second counter connected to said first counter for receiving said increased interval pulses, said second counter having a plurality of selectable output states for producing control pulses, and control means connected between said second counter and said flash tube to receive said control pulses, said control means providing trigger pulses to said flash tube to enable said stored electrical energy to discharge through said flash tube.

Claim 10

The firing circuit of claim 7, further including: a resistive feedback circuit connected between said transformer and said electronic clock means for generating a modulation signal functionally related to said input current of said primary winding, and means connected between said feedback circuit and said electronic clock means for receiving said modulation signal and for modulating said first output pulse to a width effective to maintain said input current at a level less than a saturation current for said transformer.

Claim 11

The firing circuit of claim 7, further including: transient damping circuits of resistor, capacitor and diode combinations connected across both said primary winding and said secondary winding to reduce self-induced transient voltages in said primary and secondary windings.

Claim 12

The firing circuit of claim 7, further including: shutdown means connected between said control means and said electronic clock means and responsive to said control pulses for inhibiting generation of said first output pulse train for a selected interval after said discharge through said flash tube.

Claim 13

The firing circuit of claim 7, wherein said feedback circuit further includes: a photocell circuit for regulating said stored electrical energy as a function of ambient lighting.

Claim 14

Strobe light firing circuit for triggering a flash tube, comprising: electronic clock means for generating a first output pulse train having a modulated pulse width and a second output pulse train having said modulated pulse width, a transformer having a primary winding and a secondary winding having an electrical energy output, an FET switch connected between said electronic clock means and said transformer, said FET receiving said first output pulse train and producing a rapidly changing input current in said primary winding, firing capacitor storage means connected between said secondary winding and said flash tube for storing said electrical energy output by said secondary winding, a resistive feedback circuit connected between said transformer and said electronic clock means for generating a modulation signal functionally related to said input current of said primary winding, means connected between said feedback circuit and said electronic clock means for receiving said modulation signal and for modulating said first output pulse to a width effective to maintain said input current at a level less than a saturation current for said transformer, transient damping circuits of resistor, capacitor and diode combinations connected across both said primary winding and said secondary winding to reduce self-induced transient voltages in said primary and secondary windings, pulse counter means connected to said electronic clock means for receiving said second output pulse train, said pulse counter means producing control pulses at selected intervals, and control means connected between said pulse counter means and said flash tube to receive said control pulses, said control means providing trigger pulses to said flash tube to enable said stored electrical energy to discharge through said flash tube.

Claim 15

Strobe light firing circuit for triggering a flash tube, comprising: electronic clock means for generating a first output pulse train having a modulated pulse width and a second output pulse train having said modulated pulse width, a transformer having a primary winding and a secondary winding having an electrical energy output, an FET switch connected between said electronic clock means and said transformer, said FET receiving said first output pulse train and producing a rapidly changing input current in said primary winding, firing capacitor storage means connected between said secondary winding and said flash tube for storing said electrical energy output by said secondary winding, a resistive feedback circuit connected between said transformer and said electronic clock means for generating a modulation signal functionally related to said input current of said primary winding, means connected between said feedback circuit and said electronic clock means for receiving said modulation signal and for modulating said first output pulse to a width effective to maintain said input current at a level less than a saturation current for said transformer, transient damping circuits of resistor, capacitor and diode combinations connected across both said primary winding and said secondary winding to reduce self-induced transient voltages in said primary and secondary windings, pulse counter means connected to said electronic clock means for receiving said second output pulse train, said pulse counter means producing control pulses at selected intervals, and control means connected between said pulse counter means and said flash tube to receive said control pulses, said control means providing trigger pulses to said flash tube to enable said stored electrical energy to discharge through said flash tube.

Claim 16

The firing circuit of claim 12, wherein said pulse counter means further includes: a binary counter for producing pulses at an increased interval relative to said second output pulse train, and a decade counter connected to said binary counter, said decade counter having a plurality of selectable output states for deriving said control pulses from said increased interval pulses.

Claim 17

The firing circuit of claim 13, further including: shutdown means connected between said control means and said electronic clock means and responsive to said control pulses for inhibiting generation of said first output pulse train for a selected interval after said discharge through said flash tube.

Claim 18

The firing circuit of claim 14, wherein said feedback circuit further includes: a photocell circuit for regulating said stored electrical energy as a function of ambient lighting.

Claim 21

A method according to claim 16, further including the step of: modulating the width of pulses in said second output pulse train to maintain said primary current less than a saturation current for said primary winding.

Claim 22

A method according to claim 16, further including the steps of: generating an error signal responsive to said increasing average voltage across said capacitor storage means, and generating said first output pulse train at a pulse amplitude functionally related to said error signal to maintain said predetermined firing voltage for delivery to said flash tube.

Claim 23

A method according to claim 16, wherein the step of deriving said trigger pulses comprises the steps of: dividing said second pulse train to form a third output pulse train having a pulse interval substantially longer than said selected pulse interval for said second pulse train, inputting said third pulse train to a decade counter to form sequential signals on output terminals of said decade counter, and selecting signals from said output terminals to form said trigger pulses at said predetermined intervals.

Claim 24

A method according to claim 16, further including: deriving a shutdown pulse in response to a said trigger pulse effective to terminate at least said first pulse train for a time effective for flash tube recovery.

Claim 25

A method according to claim 16, further including: adjusting said firing voltage obtained across said capacitor storage means as a function of ambient light conditions.

Claim 28

The firing circuit of claim 22, further including: generating an error signal responsive to said increasing average voltage across said capacitor storage means, and generating said first output pulse train at a pulse width functionally related to said error signal to maintain said predetermined firing voltage for delivery to said flash tube.

Claim 29

The firing circuit of claim 23, further including: deriving a shutdown pulse in response to a said trigger pulse effective to terminate at least said first pulse train for a time effective for flash tube recovery.

Claim 30

The firing circuit of claim 24, further including: adjusting said firing voltage obtained across said capacitor storage means as a function of ambient light conditions.

Claim 31

In a strobe light flashing system having a control circuit for delivering stored power to a flash tube at selected intervals, power generation and storage circuitry comprising: electronic clock means for generating a first output pulse train having a modulated pulse width effective to controllably generate high voltage for application to said strobe light and a second output pulse train for use in deriving a control pulse effective to deliver said stored power for flashing said strobe light, a transformer having a primary winding for receiving an input current and a secondary winding having an output voltage related to the rate of change of said input current in said primary winding, an FET switch controlled by said first output pulse train for rapidly reducing said input current in said primary winding, and firing capacitor storage means connected across said secondary winding for storing electrical energy produced by said secondary winding when said FET reduces said current in said primary winding.

Claim 32

In a strobe light flashing system having a control circuit for delivering stored power to a flash tube at selected intervals, power generation and storage circuitry comprising: electronic clock means for generating a first output pulse train having a modulated pulse width effective to controllably generate high voltage for application to said strobe light and a second output pulse train for use in deriving a control pulse effective to deliver said stored power for flashing said strobe light, a transformer having a primary winding for receiving an input current and a secondary winding having an output voltage related to the rate of change of said input current in said primary winding, an FET switch controlled by said first output pulse train for rapidly reducing said input current in said primary winding, and firing capacitor storage means connected across said secondary winding for storing electrical energy produced by said secondary winding when said FET reduces said current in said primary winding.

Claim 33

The circuit of claim 26, further including: a resistive circuit for generating a modulation signal functionally related to said input current of said primary winding, and means responsive to said modulation signal for modulating said first output pulse to a width effective to maintain said input current at a level less than a saturation current for said transformer.

Claim 34

The circuit of claim 27, further including: transient damping circuits of resistor, capacitor and diode combinations across said primary winding and said secondary winding to reduce self-induced transient voltages in said primary and secondary windings.

Claim 35

In a strobe light flashing system having an energy generation and storage system for storing energy at a voltage effective to discharge a flash tube, a circuit for controlling delivery of said stored energy to said flash tube, comprising: electronic clock means for generating a first output pulse train having a modulated pulse width effective to generate said energy for storage and a second output pulse train for use in deriving a control pulse effective to deliver said energy to said flash tube, pulse counter means connected to said electronic clock means for receiving said second output pulse train, said pulse counter means producing control pulses at selected intervals, and control means connected between said pulse counter means and said flash tube to receive said control pulses, said control means providing trigger pulses to said flash tube to enable said stored electrical energy to discharge through said flash tube.

Claim 36

In a strobe light flashing system having an energy generation and storage system for storing energy at a voltage effective to discharge a flash tube, a circuit for controlling delivery of said stored energy to said flash tube, comprising: electronic clock means for generating a first output pulse train having a modulated pulse width effective to generate said energy for storage and a second output pulse train for use in deriving a control pulse effective to deliver said energy to said flash tube, pulse counter means connected to said electronic clock means for receiving said second output pulse train, said pulse counter means producing control pulses at selected intervals, and control means connected between said pulse counter means and said flash tube to receive said control pulses, said control means providing trigger pulses to said flash tube to enable said stored electrical energy to discharge through said flash tube.

Claim 37

The circuit of claim 29, further including: shutdown means connected between said control means and said electronic clock means and responsive to said control pulses for inhibiting generation of said first output pulse train for a selected interval after said discharge of energy through said flash tube.

Claim 38

The circuit of claim 29, wherein said feedback circuit further includes: a photocell circuit for regulating said stored energy delivered to said flash tube as a function of ambient lighting.

Claim 39

The circuit of claim 29, wherein said pulse counter means further includes: a first counter connected to said electronic clock means for receiving said second output pulse train and for providing pulses at an increased interval relative to said second output pulse train, and a second counter connected to said first counter for receiving said increased interval pulses, said second counter having a plurality of selectable output states for producing said control pulses.