Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
  • H05B41/14—Circuit arrangements
  • H05B41/30—Circuit arrangements in which the lamp is fed by pulses, e.g. flash lamp
  • H05B41/34—Circuit arrangements in which the lamp is fed by pulses, e.g. flash lamp to provide a sequence of flashes

Definitions

• This invention relates, in general, to warning systems for emergency vehicles and, in particular, to an improved warning system employing one or more flash tubes being triggered to produce two or more light flashes in rapid succession.
• this invention relates to a warning system having one or more flash tubes which are flashed in rapid succession for a duration of approximately 30-90 milliseconds for greatly improving the perception of brightness and the warning light conspicuity. Because the two or more light flashes are closely spaced, they appear as a single flash of light to the observer.
• a flash tube has been found to be a greatly effective warning light producing a brief, but highly intense flash.
• strobe lights are gas filled tubes which may produce brief flashes having a duration of around 200 microseconds.
• Another object of this invention is to create two or more strobe flashes at the Broca-Sulzer duration to enhance appearance of brightness and warning light conspicuity.
• an improved flash tube system taking advantage of the Broca-Sulzer effect in a manner that enhanced brightness of flash is attained by increased awareness of a warning light by an observer.
• the invention of the application uses two or more flashes in rapid succession generated by a flash tube having a flash duration of 30-90 milliseconds to conform to the Broca-Sulzer effect.
• the two flashes create an apparent brightness in accordance with the present invention of 5-6 times what is possible with a steady light of similar illumination, because the time interval between the two or more pulses is within a critical range. Because the frequency of the flashes is higher than the so-called "flicker fusion frequency", the two flashes appear as a single flash.
• the invention of the application is capable of attaining a greater perceptible brightness using a standard flash tube than is possible in prior art devices using either multiple pulse light flashes or moving reflectors.
• Figure 1 is an electrical circuit diagram of one embodiment of the invention of the application for a double flash flash tube
• Figure 2 is a timing chart showing representative operation of the circuit of Figure 1.
• circuit and method for operating one or more flash tubes in a manner that an enhancement of perceived brightness is attained of. up to 5-6 times Although many similar circuits and arrangements may be employed, the circuit shown in Figure 1 is illustrative of one technique of attaining the objects of the invention. It is within the scope of the invention to utilize other circuits and systems to attain the improved results of the invention, such that two or more brief flashes produced by a flash tube are created during a selected time interval for enhanced brightness appearing as a single flash.
• the flash tube of Figure 1 is arranged to create two or more flashes spaced by successive intervals of 30-90 milliseconds. It is found that a warning light system employing the technique in the invention appears to be approximately 5-6 times as bright as a light of equal lumens having a steady output, dependent on the magnitude of the duration in the approximate range of 30-90 milliseconds. Because the flashes from the flash tube of the invention are so closely spaced, they appear as a single flash of light having a duration approximately equal to intervals between flashes.
• flash lamp 10 is shown therein comprising a flash tube 12, a transformer 14, and a capacitor 16 mounted in conjunction with a contact base and body portion (not shown).
• Flash tube 12 may comprise a conventional flash tube having a first electrode 20 which, for convenience, will be designated an anode; a second electrode 22 which, for convenience, will be designated a cathode; and a trigger electrode 24 which extends from metal trigger band (not shown).
• first electrode 20 which, for convenience, will be designated an anode
• second electrode 22 which, for convenience, will be designated a cathode
• trigger electrode 24 which extends from metal trigger band (not shown).
• flash tube 12 may be General Electric Model FT-106C.
• Transformer 14 is generally a miniature transformer and although no limitation is intended, transformer 14 may comprise a Siemens ZS-1062 transformer.
• Capacitor 16 is preferably a disc ceramic capacitor and although no limitation is intended, capacitor 16 may comprise a Sprague 5GAS-S10 capacitor.
• Electrical lead 30 couples anode 20 to lead 32 of capacitor 16, while lead 34 of capacitor 16 is connected to one side 36 of transformer primary 38.
• Lead 40 connects the other side of transformer primary 40 to the ground contact of lamp 10 and to one side of the transformer secondary 42, while lead 44 connects trigger electrode 26 to the other side of the transformer secondary 48.
• Lead 45 connects the latter elements to the ground of the power supply PSx.
• the cathodes of a pair of silicon controlled rectifiers SCRi and SCR2 are connected together by electrical leads 46 and 48 extending from lead 30.
• the anodes of SCRi and SCR are respectively connected to a power supply PS through leads 50 and 52 having diodes CRi and CR2 in series with SCRi and SCR2.
• Flash capacitors Ci and C2, respectively, are connected between lead 50 and 52; and lead 45 by leads 54a, b and 56 a, b.
• the gates 60 and 62 of SCRi and SCR2 are each connected to a timing circuit 64 through transformer 66.
• the timing circuit 64 can comprise any suitable device such as the timer of National Semiconductor, Model LM555.
• the power supply PSi charges capacitor Ci and C2 to the desired energy level through diodes CRi and CR2 during a time interval, tj.
• a positive going edge occurs on terminal 1 of the timing circuit 64 causing SCRi to conduct.
• SCRi goes into conduction, a positive pulse appears on the trigger capacitor 16 causing flash tube 12 to fire, discharging capacitor C -
• time t2 the Broca-Sulzer interval
• a negative going edge occurs on terminal 1 of the timing circuit 14 causing SCR2 to conduct.
• Flash tube 12 again fires discharging capacitor C2.
• Capacitors C and C2 discharge in approximately 2 milliseconds, thereby limiting the minimum value of time interval t2 «
• timing graph is shown providing an example of energy levels and time intervals provided by the circuit of Figure 1. It should be understood that other energy levels and time intervals, ti and t2, may be employed, by which the flash tube 12 is flashed sequentially within an interval equal to the critical ranges of approximately 30-90 milliseconds in accordance with the invention, where optimum brightness generally occurs in the mid portion of this range.
• timer 64 produces an output of 5 volts during interval t2 of 75 milliseconds.
• Both capacitors Ci and C2 may be charged to a voltage of 450 volts through diodes CRi and CR2.
• the circuit then applies as voltage across capacitor 16 of 450 volts for a period to produce two successive flashes of about 2 milliseconds spaced by a time period of about 75 milliseconds within the critical range.
• the flashes then occur at a frequency greater than "flicker fusion frequency" to appear as a single flash of light having a duration of 75 milliseconds and perceived brightness of 5-6 times normal brightness and, thus, increased warning light conspicuity.
• the flash lamp 12 operated in accordance with the invention may be used with other similar flash lamps in a warning system of any appropriate design.
• the invention herein disclosed may also accomplish the objects of invention by flashing a strobe light for more than two successive flashes as long as the time between flashes is within the separation of 30-90 milliseconds.

Landscapes

• Non-Portable Lighting Devices Or Systems Thereof (AREA)
• Discharge-Lamp Control Circuits And Pulse- Feed Circuits (AREA)
• Audible And Visible Signals (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=24084941

Family Applications (1)

Country Status (6)

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Citations (1)

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• 1984
  • 1984-07-18 GB GB08506902A patent/GB2155710B/en not_active Expired
  • 1984-07-18 JP JP59502978A patent/JPS61500086A/ja active Pending
  • 1984-07-18 WO PCT/US1984/001129 patent/WO1985000950A1/en not_active Application Discontinuation
  • 1984-07-18 EP EP84902986A patent/EP0153345A1/en active Pending
  • 1984-07-20 CA CA000459364A patent/CA1235210A/en not_active Expired
  • 1984-08-08 KR KR1019840004732A patent/KR890003061B1/ko active IP Right Grant

Patent Citations (1)

Non-Patent Citations (1)

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