Trigger device for an electronic flash unit

Claim 2

In an electronic flash unit including first and second electrical conductors, a flashtube containing an ionizable gas having (1) a normal, first state in which said gas constitutes an electrically non-conductive medium, and (2) an ionized, second state in which said gas constitutes an electrically conductive medium, said flashtube further including two opposed primary electrodes, and an external trigger electrode responsive to an electrical trigger-control signal for ionizing said flashtube gas, said trigger electrode being connected to said first electrical conductor and one of said primary electrodes being connected to said second conductor, an improved trigger mechanism for said electronic flash unit comprising: (a) a piezoelectric generator having first and second electrical output contacts coupled to said first and second conductors, respectively; and (b) an inductor interconnecting said first and second output contacts, said inductor having an inductance of a magnitude for producing upon actuation of said piezoelectric generator a trigger-control signal having a series of oscillations that occur over an extended period of time, said trigger-control signal being effective to change said flashtube gas from said first state to said second state to produce an electrically conductive path between said primary electrodes.

Claim 3

In an electronic flash unit including first and second electrical conductors, a flashtube containing ionizable gas having (1) a normal, first state in which said gas constitutes an electrically non-conductive medium, and (2) an ionized, second state in which said gas constitutes an electrically conductive medium, said flashtube including two primary electrodes, and an external trigger electrode responsive to an electrical trigger-control signal for ionizing said flashtube gas, said trigger electrode being connected to said first electrical conductor and one of said primary electrodes being connected to said second conductor, an improved trigger mechanism for said electronic flash unit comprising: (a) a piezoelectric generator including a piezoelectric crystal having first and second output contacts connected to said first and second conductors, respectively, said crystal having a particular equivalent electrical impedance characteristic; and (b) electrical control means connected between said first and second electrical conductors, said control means having a predetermined reactive impedance characteristic for forming a resonant electrical circuit with said piezoelectric crystal, said resonant circuit operating to produce an oscillatory signal having an extended period in which oscillations occur to convert said flashtube gas from said first state to said second state to provide an electrically conductive path between said primary electrodes.

Claim 4

In an electronic flash unit including first and second electrical conductors, a flashtube containing ionizable gas having (1) a normal, first state in which said gas constitutes an electrically non-conductive medium, and (2) an ionized, second state in which said gas constitutes an electrically conductive medium, said flashtube including two primary electrodes, and an external trigger electrode responsive to an electrical trigger-control signal for ionizing said flashtube gas, said trigger electrode being connected to said first electrical conductor and one of said primary electrodes being connected to said second conductor, an improved trigger mechanism for said electronic flash unit comprising: (a) a piezoelectric generator including a piezoelectric crystal having first and second output contacts connected to said first and second conductors, respectively, said crystal having a particular equivalent electrical impedance characteristic; and (b) electrical control means connected between said first and second electrical conductors, said control means having a predetermined reactive impedance characteristic for forming a resonant electrical circuit with said piezoelectric crystal, said resonant circuit operating to produce an oscillatory signal having an extended period in which oscillations occur to convert said flashtube gas from said first state to said second state to provide an electrically conductive path between said primary electrodes.

Claim 5

In an electronic flash unit including a flashtube containing an ionizable gas having (1) a normal, first state in which said gas constitutes an electrically non-conductive medium and (2) an ionized second state in which said gas constitutes an electrically conductive medium, said flashtube further including (1) an external trigger electrode responsive to an electrical trigger signal for ionizing said flashtube gas, and (2) two primary electrodes, an improved trigger mechanism for said electronic flash unit comprising: (a) a piezoelectric crystal having a particular equivalent electrical impedance characteristic; (b) means electrically coupling said piezoelectric crystal to said trigger electrode and one of said primary electrodes; (c) auxiliary electrical control means having an impedance characteristic for effectively forming a resonant circuit in combination with said piezoelectric crystal, said resonant circuit operating to produce upon actuation of the piezoelectric crystal an oscillatory voltage signal having an extended period in which oscillations occur; and (d) means for supplying said oscillatory voltage signal to said trigger electrode, said oscillatory signal being effective to change said flashtube gas from said first state to said second state to establish an electrically conductive path between said primary electrodes.

Claim 6

In an electronic flash unit including a flashtube containing an ionizable gas having (1) a normal, first state in which said gas constitutes an electrically non-conductive medium and (2) an ionized second state in which said gas constitutes an electrically conductive medium, said flashtube further including (1) an external trigger electrode responsive to an electrical trigger signal for ionizing said flashtube gas, and (2) two primary electrodes, an improved trigger mechanism for said electronic flash unit comprising: (a) a piezoelectric crystal having a particular equivalent electrical impedance characteristic; (b) means electrically coupling said piezoelectric crystal to said trigger electrode and one of said primary electrodes; (c) auxiliary electrical control means having an impedance characteristic for effectively forming a resonant circuit in combination with said piezoelectric crystal, said resonant circuit operating to produce upon actuation of the piezoelectric crystal an oscillatory voltage signal having an extended period in which oscillations occur; and (d) means for supplying said oscillatory voltage signal to said trigger electrode, said oscillatory signal being effective to change said flashtube gas from said first state to said second state to establish an electrically conductive path between said primary electrodes.

Claim 7

In an ignition arrangement for a discharge tube containing an ionizable gas having (1) a normal, first state in which said gas constitutes an electrically non-conductive medium, and (2) an ionized second state in which said gas constitutes an electrically conductive medium, said flashtube further including (1) an external trigger electrode responsive to an electrical signal for ionizing said gas, and (2) two primary electrodes, an improved mechanism for ionizing said gas comprising: (a) a piezoelectric crystal, having a particular equivalent electrical impedance characteristic, for producing an electrical voltage signal; (b) electrical control means having an electrical impedance for effectively forming a resonant circuit in combination with said piezoelectric crystal to produce an oscillatory voltage; and (c) means for applying said oscillatory voltage to said trigger electrode to change said gas from said first state to said second state whereby an electrically conductive path between said primary electrodes is reliably established.

Claim 8

In an ignition arrangement for a discharge tube containing an ionizable gas having (1) a normal, first state in which said gas constitutes an electrically non-conductive medium, and (2) an ionized second state in which said gas constitutes an electrically conductive medium, said flashtube further including (1) an external trigger electrode responsive to an electrical signal for ionizing said gas, and (2) two primary electrodes, an improved mechanism for ionizing said gas comprising: (a) a piezoelectric crystal, having a particular equivalent electrical impedance characteristic, for producing an electrical voltage signal; (b) electrical control means having an electrical impedance for effectively forming a resonant circuit in combination with said piezoelectric crystal to produce an oscillatory voltage; and (c) means for applying said oscillatory voltage to said trigger electrode to change said gas from said first state to said second state whereby an electrically conductive path between said primary electrodes is reliably established.