Gas multiplication ultraviolet detector system for fire detection

Claim 2

A fire detecting system comprising: a. a gas multiplication ultraviolet tube for receiving ultraviolet radiation; b. means for supplying a high voltage direct current potential to the said tube to provide ionization of the tube when the tube receives the said radiation; c. means for extinguishing the ionization of the said tube after a predetermined interval of time from the onset of ionization; d. means for sensing the current flow through the said tube and providing a voltage potential responsive to the magnitude of the said current; e. an amplitude discriminator, cooperating with the said voltage potential provided by the current sensing means, for providing an output each time the said voltage potential exceeds a predetermined threshold value; f. a time discriminator cooperating with the output of the said amplitude discriminator for providing an output signal when more than two signals are received from the said amplitude discriminator in a predetermined time period; and g. means responsive to the output of the said time discriminator for indicating the presence of a fire.

Claim 3

The apparatus as claimed in claim 1 wherein the said predetermined time period of the time discriminator is approximately forty milliseconds.

Claim 4

The apparatus as claimed in claim 2 wherein the said predetermined time interval for extinguishing the ionization of the ultraviolet tube after the onset of ionization is approximately 2 milliseconds.

Claim 5

A fire detecting system comprising: a. a gas multiplication ultraviolet tube for receiving ultraviolet radiation; b. means for providing a direct current potential to the said tube to provide ionization of the tube when it receives ultraviolet radiation; c. means for providing approximately a 2-millisecond time interval; d. means for initiating the said 2-millisecond time interval approximately at the onset of the said ionization of the ultraviolet tube; e. means cooperating with the said 2-millisecond time interval and the said direct current potential for substantially removing the said direct current potential from the ultraViolet tube at the end of the said 2-millisecond time interval; f. means for sensing the current flow through the said ultraviolet tube and providing an output when the said current exceeds a predetermined value; g. means for providing approximately a 40-millisecond time interval; h. means cooperating with the output of the said means for sensing current, for initiating the said 40-millisecond time interval when the said current sensing means provides an output; i. a counter responsive to the said output of the means for sensing the current through the ultraviolet tube cooperating with the said 40-millisecond time interval for providng an output upon the occurrence of a third count in the said 40-millisecond time interval; and j. means responsive to the output of the said counter for indicating a fire.

Claim 6

A fire detecting system comprising: a. a gas multiplication ultraviolet tube for receiving ultraviolet radiation; b. means for providing a direct current potential to the said tube to provide ionization of the tube when it receives ultraviolet radiation; c. means for providing approximately a 2-millisecond time interval; d. means for initiating the said 2-millisecond time interval approximately at the onset of the said ionization of the ultraviolet tube; e. means cooperating with the said 2-millisecond time interval and the said direct current potential for substantially removing the said direct current potential from the ultraViolet tube at the end of the said 2-millisecond time interval; f. means for sensing the current flow through the said ultraviolet tube and providing an output when the said current exceeds a predetermined value; g. means for providing approximately a 40-millisecond time interval; h. means cooperating with the output of the said means for sensing current, for initiating the said 40-millisecond time interval when the said current sensing means provides an output; i. a counter responsive to the said output of the means for sensing the current through the ultraviolet tube cooperating with the said 40-millisecond time interval for providng an output upon the occurrence of a third count in the said 40-millisecond time interval; and j. means responsive to the output of the said counter for indicating a fire.

Claim 7

The apparatus as claimed in claim 4 wherein the said predetermined time interval that the direct current potential is removed from the ultraviolet tube is approximately 2 milliseconds.

Claim 8

The apparatus as claimed in claim 5 wherein the said gas multiplication ultraviolet tube is a hydrogen-helium, tungsten photocathode type tube and the said means for sensing current through the tube provides an output when the said current exceeds approximately 1.6 milliamperes.