FAIL TO FLASH INDICATOR CIRCUIT

• US 3,626,401 A
• Filed: 03/19/1969
• Issued: 12/07/1971
• Est. Priority Date: 03/19/1969
• Status: Expired due to Term

• Current Assignee: Robert A. Flieder, Sumner S. Averett
• Original Assignee: Robert A. Flieder, Sumner S. Averett
• Inventors: Flieder, Robert A., Averett, Sumner S.
• Primary Examiner(s): Caldwell, John W.
• Assistant Examiner(s): Wannisky, William M.
• Application Number:
  US04/808,583
• Time in Patent Office: 993 Days
• Field of Search: 340/251,253,252 315/129 314/9 324/20,21 95/11.5R,11.5A
• US Class Current: 340/641
• CPC Class Codes: H05B 41/46 Circuits providing for substitution in case of failure of the lamp

Abstract

A fail to flash alarm circuit including a main capacitor flash supply means and flash initiating means to discharge the capacitor into a discharge lamp. Control means includes alarm means so arranged as to be responsive to the actuation of the flash initiating means in the absence of current flow to the discharge lamp, this condition being determined by a current sensing resistor which is connected in the circuit to the discharge lamp to actuate switching means to block actuation of the alarm means. Bias means for the switching means may include a supervised charging circuit arranged so that bias means is not available to prevent a fail to flash alarm in the event the main capacitor is not fully charged. The bias means is connected through a voltage dropping resistor for normally dropping the control voltage to the second switching means. The drop in voltage is nullified current passed to the discharge lamp as sensed through the current sensing means and used to back bias the diodes to prevent the voltage drop and block actuation of the alarm. The circuit provides an alarm in the event the discharge lamp fails to be powered by current or in the event the main capacitor is not fully charged.

Claims

1. A fail to flash alarm circuit for a discharge lamp circuit including flash supply means incorporating a main capacitor and flash initiating means to discharge the flash supply means to the discharge lamp, the fail to flash circuit comprising alarm means responsive to the actuation of said flash initiating means, and alarm override means responsive to the current flowing in said discharge lamp and coupled to said alarm means for preventing actuation of said alarm means when current flows from said flash supply means to said discharge lamp and for allowing actuation of said alarm means when current fails to flow from said flash supply means to said discharge lamp, whereby said alarm circuit signals a fail to flash condition by the absence of current flow to the discharge lamp upon the actuation of said flash initiating means.

2. A fail to flash circuit according to claim 1 in which said alarm means normally responsive to the actuation of said flash initiating means includes transistor switching means, control means for said transistor responsive to said flash initiating means, and time delay means holding off actuation of said alarm means for a predetermined time.

3. A fail to flash circuit according to claim 2 in which said time delay means is a RC circuit.

4. A fail to flash alarm circuit for a discharge lamp circuit including flash supply means incorporating a main capacitor and flash initiating means to discharge the flash supply means to the discharge lamp, said fail to flash circuit comprising alarm means normally responsive to the actuation of said flash initiating means, and means responsive to current flow from said flash supply means to the discharge lamp for preventing actuation of said alarm means whereby said alarm circuit signals a fail to flash condition by the absence of current flow to the discharge lamp upon the actuation of said flash initiating means, said means responsive to current flow from said flash supply means to said discharge lamp including a current sensing resistor adapted to be connected in series with said discharge lamp.

5. A fail to flash circuit according to claim 4 in which said means responsive to current flow from said flash supply means includes switching means, circuit means connected to said switching means so that actuation of said switching means blocks normal operation of said alarm means, bias means for said switching means, means normally causing current flow in one direction to said current sensing resistor thereby reducing said bias means, said circuit so arranged that current flow from said current sensing means responsive to current flow from said flash supply means to said discharge lamp is in the opposite direction from said one direction so that the effect on said bias means is nullified when discharge current flows to said lamp, said unreduced bias means effective to control said switching means to block normal operation of said alarm means.

6. A fail to flash alarm circuit for a discharge lamp circuit including flash supply means incorporating a main capacitor and flash initiating means to discharge the flash supply means to the discharge lamp, the fail to flash circuit comprising alarm means normally responsive to the actuation of said flash initiating means, and means responsive to current flow from said flash supply means to the discharge lamp for preventing actuation of said alarm means whereby said alarm circuit signals a fail tO flash condition by the absence of current flow to the discharge lamp upon the actuation of said flash initiating means, said means responsive to current flow from said flash supply means to said discharge lamp including a current sensing resistor adapted to be connected in series with said discharge lamp, transistor switching means, means connecting said transistor switching means in a circuit with said alarm means normally responsive to the actuation of said flash initiating means so that normal alarm operation is blocked by operation of said switching means, bias means normally effective to actuate said switching means, voltage dropping means connected to said bias means, said current sensing resistor adapted to produce a voltage responsive to said current flow, circuit means to apply said voltage in opposition to the voltage of said bias means whereby upon a failure to flash of said discharge lamp said switching means is inoperative and said alarm is actuated.

7. A fail to flash circuit according to claim 6 in which said bias means includes a source of current, a voltage dropping resistor and a diode connected in series to said voltage sensing resistor, said switching means controlled through said voltage dropping resistor, so that normally the bias on the switching means is the junction voltage of the diode, the voltage dropping resistor so connected that potential therefrom is in opposition to the junction voltage of the diode so that the diode is back biased whereby the bias voltage on the switching means rises causing actuation thereof and the blocking of said fail to flash alarm.

8. A fail to flash circuit according to claim 7 in which said source of current includes means responsive to current flow from said charging circuit to said capacitor below a predetermined amount, and switching means for said source of current controlled by said last mentioned means so that said source of current is not available until the desired amount of charge is on the capacitor bank, whereby a fail to flash signal is provided in the absence of potential from said source upon the actuation of said flash initiating means.

9. A fail to flash circuit according to claim 7 in which said source of current includes a main current sensing resistor adapted to be connected in series with the main capacitor for sensing current flow thereto, a capacitor and a diode connected in series across said current sensing resistor, a pair of transistors connected as s direct coupled amplifier and controlled by the potential on said capacitor to provide closed switching means in the absence of a potential on said capacitor so that the source of current is not connected to said voltage dropping resistor until current flow has ceased to said main capacitor whereby an actuation of the flash initiating means will produce a fail to flash alarm.

10. A fail to flash alarm circuit for a discharge lamp circuit including flash supply means incorporating a main capacitor and flash initiating means to discharge the flash supply means to the discharge lamp, the fail to circuit comprising alarm means normally responsive to the actuation of said flash initiating means, and means responsive to current flow from said flash supply means to the discharge lamp for preventing actuation of said alarm means whereby said alarm circuit signals a fail to flash condition by the absence of current flow to the discharge lamp upon the actuation of said flash initiating means, said alarm means normally responsive to the actuation of said flash initiating means including first transistor means control means for said first transistor responsive to said flash initiating means, and time delay means, a current sensing resistor adapted to be connected in series with said discharge lamp, second transistor switching means connected in opposition to said first transistor switching means and blocking operation of said alarm means, bias means effective to operate said second switching means, voltage dropping means for said bias means, diode meAns connected between said voltage dropping means and said current sensing means, said bias means poled with respect to said current sensing means so that current flow through said diode is blocked by current from said current sensing means whereby upon the usual operation of said discharge by said flash initiating means the failure to flash alarm is not given but is given in the event of the absence of current flow in said current sensing means.

11. A fail to flash circuit according to claim 10 in which said bias means includes a main current sensing resistor adapted to be connected in series with the main capacitor for sensing current flow thereto, a capacitor and a diode connected in series across said current sensing resistor, a pair of transistors connected as a direct current amplifier and controlled by the potential on said capacitor to provide closed switching means in the absence of a potential on said capacitor so that the source of current is not connected to said voltage dropping resistor until current flow has ceased to said main capacitor.