Microprocessor-controlled strobe light

• US 5,341,069 A
• Filed: 05/14/1993
• Issued: 08/23/1994
• Est. Priority Date: 05/14/1993
• Status: Expired

• Current Assignee: Wheelock Incorporated (Eaton Corporation PLC.)
• Original Assignee: Wheelock Incorporated (Eaton Corporation PLC.)
• Inventors: Kosich, Joseph, Applegate, Edward V.
• Primary Examiner(s): Pascal, Robert J.
• Assistant Examiner(s): Philogene, Haissa
• Application Number:
  US08/061,965
• Time in Patent Office: 466 Days
• Field of Search: 315/241 S, 315/241 P, 315/241 R, 315/292, 315/294, 315/323, 340/384 E, 340/518, 340/628, 340/52 F, 358/214, 364/141
• US Class Current: 315/241.00S
• CPC Class Codes: H05B 41/34 to provide a sequence of flashes

Abstract

A flashtube circuit includes a switch which in a first position regulates the storage over time of energy in a first energy storage device and in a second position allows the transfer of energy from the first energy storage device to a second energy storage device. A microcontroller receives the input voltage and then samples and digitizes it for input into a lookup table. The microcontroller repeatedly cycles the switch between flashes by controlling the time the switch is in its first position. The lookup table output provides the signal for determining the time the switch remains in its first position. The time interval from the last flash controls the time the switch is in its second position. The cycling of the switch is controlled accordingly such that the second energy storage device acquires the predetermined amount of energy for the flash just as the triggering circuit is initiated by the microcontroller. Moreover, the microcontroller controls the switch in a way such that the time the switch is in its first position is maximized and the time the switch is in its second position is generally decreased relative to the time since the last flash. This helps to minimize the peak current drawn by the first energy storage device. In addition, the strobe light circuit is capable of determining if the input voltage is D.C. or is full wave rectified and controls the switch accordingly.

Claims

1. A strobe light circuit powered by an input voltage, for flashing a flashtube at a predetermined flash rate with a predetermined amount of energy in each flash, comprising:

first means for storing energy supplied from said input voltage;

second means for storing energy, connected in shunt with said flashtube and capable of storing energy at a rate faster than said first storing means;

switching means for regulating the storage over time of energy in said first storing means and for allowing transfer of energy from said first storing means to said second storing means, said switching means having a first position and a second position such that when said switching means is in said first position, energy is stored in said first storing means and when said switching means is in said second position, energy from said first storing means is transferred to said second storing means, and such that a relative peak current drawn by said first storing means is attained as said switching means switches from said first position to said second position;

means for permitting current flow from said first storing means to said second storing means and for blocking current flow from said second storing means to said first storing means or said switching means;

means for triggering said flashtube at said predetermined flash rate;

means for regulating said input voltage into a regulated voltage supply; and

microcontroller means powered by said regulated voltage supply, for initiating said triggering means at the predetermined flash rate, for receiving said input voltage, for sampling and digitizing said input voltage into a lookup table input having a corresponding D.C. lookup table output, and for repeatedly cycling said switching means between flashes of said flashtube by controlling the time said switching means is in said first position in accordance with the lookup table output, and controlling the time said switching means is in said second position in accordance with the time expended since the last flash of said flashtube, such that said second energy storing means acquires said predetermined amount of energy as the triggering means is initiated by the microcontroller means and such that the time said switching means is in said first position is maximized and the time said switching means is in said second position is generally decreased relative to the time since the last flash of said flashtube, to minimize the peak current drawn by the first storing means.

2. The strobe light circuit according to claim 1, wherein said microcontroller means is capable of sampling and digitizing said input voltage each time said switching means cycles.

3. The strobe light circuit according to claim 2, wherein the microcontroller means segregates the time between said flashes into a plurality of periods, such that said microcontroller means controls the time during each cycle of the switching means in which said switching means is in said second position to be substantially the same throughout the same period.

4. The strobe light circuit according to claim 3, wherein the time during each cycle of the switching means in which said switching means is in said second position is decreased in subsequent periods.

5. The strobe light circuit according to claim 4, wherein said switching means cycles in a range substantially between 3 khz and 30 khz.

6. The strobe light circuit according to claim 5, wherein said flash rate is substantially one flash per second.

7. The strobe light circuit according to claim 6, wherein said input voltage is in a range substantially between 20 volts and 31 volts D.C.

8. The strobe light circuit according to claim 4, wherein said periods are substantially multiples of a fraction of the flash rate.

9. The strobe light circuit according to claim 8, wherein said fraction is one-fifteenth.

10. The strobe light circuit according to claim 4, further comprising an input feed network for reducing the input voltage to the microcontroller means.

11. The strobe light circuit according to claim 10, wherein said input feed network includes a potentiometer for finely controlling the reduction of said input voltage.

12. The strobe light circuit according to claim 4, wherein the switching means is a field effect transistor.

13. The strobe light circuit according to claim 12, wherein the means for permitting and blocking current flow is a diode.

14. The strobe light circuit according to claim 13, wherein the first energy storing means is an inductor.

15. The strobe light circuit according to claim 14, wherein the second energy storing means is a capacitor.

16. The strobe light circuit according to claim 1, wherein said microcontroller is capable of determining if said input voltage is D.C. or is full wave rectified.

17. The strobe light circuit according to claim 16, wherein said microcontroller after digitizing said input voltage has a full wave rectified lookup table output corresponding to said lookup table input when said input voltage is determined to be full wave rectified, for controlling the time said switching means is in said first position instead of said switching means being controlled by said D.C. lookup table output.

18. The strobe light circuit according to claim 17, wherein said microcontroller means varies said full wave rectified lookup table output only if said input voltage sampled and digitized is greater than the previous input voltage sampled and digitized.

19. The strobe light circuit according to claim 18, wherein said microcontroller means samples and digitizes said input voltage at a frequency less than the frequency in which said switching means cycles, utilizing the previous full wave rectified lookup table output to control the switching means until the next input voltage is sampled and digitized.

20. The strobe light circuit according to claim 19, wherein said microcontroller means samples and digitizes said input voltage at a frequency approximately one order of magnitude greater than the frequency of said flash rate.

21. The strobe light circuit according to claim 20, wherein the microcontroller means segregates the time between said flashes into a plurality of periods, such that said microcontroller means controls the time during each cycle of the switching means in which said switching means is in said second position to be substantially the same throughout the same period.

22. The strobe light circuit according to claim 21, wherein the time during each cycle of the switching means in which said switching means is in said second position is decreased in subsequent periods.

23. The strobe light circuit according to claim 22, wherein said switching means cycles in a range substantially between 3 khz and 30 khz.

24. The strobe light circuit according to claim 23, wherein said periods are substantially multiples of a fraction of the flash rate.

25. The strobe light circuit according to claim 24, wherein said input voltage is sampled and digitized at a frequency which is substantially a multiple of said fraction.