GB2295058A - Strobe lamp system - Google Patents

Description

2295058 ARCHITECTURAL STROBE FIXTURE The present invention relates

generally to controlled lamp flashing systems, and more particularly to a microprocessor controlled plurality of flash lamp fixtures to be operated in a periodic and controlled manner from a single controller.

Present xenon flash lamp fixtures, or strobes, are primarily f or indoor use. An unlimited number of such units can be linked together to provide the desired lighting effect. Strobes are used to produce a lighting effect which is pulsed at a desired rate and intensity.

One such system can use hundreds of strobes each individually addressable and dimmable. The strobes provide short duration bursts of substantial lighting intensity but are also dimmable to a sof t hue f or more subtle ef f ects. The parameter of projected light can be changed from an omnidirectional source to a narrow angle spot. Colour can be accomplished and the lamp can be used with dichroic filters. This system contains its own microprocessor which reads incoming data to determine its intensity and rate.

Present units however have a limited intensity level, that is, the pulsed light is not as bright as may be desired for some uses. Also, present units are adapted for drawing their power from a prescribed voltage source, usually 120 or 230 volts, and can only be used where a particular voltage source is available, or they may use an adapter.

Further, present devices do not operate in multiple modes such as the stand-alone mode where the microprocessor in the unit generates timing and intensity from a dip switch setting and also the controlling mode where the unit receives data f rom a central controller. In addition, present devices have a limited firing rate, i.e. seventeen flashes per second. Also, present devices will not accept multiple protocols such as where one serial protocol sends a single byte for intensity and duration, the rate being derived from the serial refresh rate and the other protocol using two bytes per strobe, one being for intensity and one being for rate, but will only accept either one or the other.

According to one aspect of the present invention, there is provided a microprocessor controlled flash lamp system comprising at least one lamp fixture; means for operating the fixture from an AC power input of between 90 volts and 255 volts without a configuration change; said means including a high voltage boost regulator circuit; and a CPU connected to receive input from the boost regulator circuit to determine the voltage that the fixture is connected to and also connected to receive input from the zero-cross detector to determine the frequency of the AC power supply by measuring the length of time between zero-cross signals.

According to another aspect of the present invention there is provided a flash lamp system including a plurality of microprocessor controlled flash lamps comprising a CPU connected to fire the lamps at a certain intensity and duration, the CPU including internal time bases and a program, and being connected to receive data from a serial link, the CPU also being connected to read a binary setting of a first dip switch which instructs the CPU to read the serial link signal for intensity, duration and time base signals, and the CPU also internally generating intensity, duration and time base signals; and a second dip switch connected to determine which serial signals are for each lamp, the CPU being connected to read the second dip switch when the CPU internally generates its own intensity, duration and time base signals.

According to a further aspect of the present invention there is provided a microprocessor controlled flash lamp system comprising a CPU connected to generate firing signals to a lamp; a trigger circuit; a f irst one shot circuit to AC couple the CPU to the trigger circuit; an SCR circuit; a boost gating circuit; and a second one shot circuit to AC couple the CPU to both the boost gating circuit and the SCR circuit, whereby the lamp is protected by both one shot circuits from a runaway firing in response to one of the firing signals being stuck in a firing state.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:- Figure 1 is a block diagram of a microprocessor controlled flashing system; Figure 2 is a view in partial cross-sectional side elevation of a strobe fixture; Figure 3 is a block diagram illustrating circuit components of the strobe fixture; and Figure 4 is a circuit diagram illustrating circuit components of the strobe fixture.

Referring to the drawings, the microprocessor controlled lamp flashing system indicated generally at 10 in Figure 1 includes a central controller 12 which provides control signals to a plurality of flash lamp assemblies or strobe fixtures 14 over a serial data link 16. This data link is capable of transmitting serial data, and this permits up to 512 flash lamp assemblies to be individually addressed. As will be noted in Figure 1, the strobe fixtures 14, three of which are shown, are serially connected by the data link 16, and each f lash lamp assembly is connected to an AC power line by an AC input 18. Each flash lamp assembly includes a housing 19 which houses a lamp control circuit. The present system includes cooldown protection of the type described in US-A-5 078 039.

The central controller 12 includes a control panel 20 which provides control buttons and indicators for the system. Thus, the control panel includes a power control switch 22 which is activated to provide power to the unit, and situated above the power control switch is a stand-by switch 24 which selectively activates or disables the output of the central controller over the serial data link 16. Normally, the lamp intensity and address data to be transmitted over the serial data link is preprogrammed in one of four memories which may be selected by switches 26. Each preprogrammed memory constitutes a group of pages wherein each page provides a scene and contains stored information concerning lamp identification addresses and intensities. An enable switch 28 initiates the preprogrammed memory operation while an advance switch 30 may be operated to manually control page advance from a selected memory.

The control panel 20 includes several display indicators, such as those indicated at 32 and 34, which display memory information, intensity information and memory page information. The programmed pages or scenes may be displayed by manually operating one of two sequence control switches 36, whereby depression of the top switch advances - the stored sequence while depression of the bottom switch reverses the sequence. The programmed intensity of various lamps may be manually altered by rotating a manual intensity control knob 37.

In some cases, it is desirable to modulate light intensity to an audio input to the central controller 12, rather than in response to prerecorded intensity information in memory. To accomplish this, a modulate switch 38 is activated and the intensity control for the flash lamp assemblies programmed on a memory page changes from the preprogrammed intensities to audio filter control. The modulate control system samples an audio input that has been filtered into different frequencies, and intensity control is no longer provided by a built-in random generator responsive to the filtered frequencies.

Finally, a send switch 40 on the control panel causes control data to be sent over the serial data link 16. Since only this relatively simple serial data control signal is required for the microprocessor controlled lamp flashing system 10, the central controller 12 is not the complex, sophisticated central controller which has been commonly employed in previously known multiple lamp display systems. In previous systems, it has been necessary to utilise complex central processors in the central controller which provide control information over multiple data links to somewhat conventional remote lamp assemblies. Unlike these systems, the microprocessor controlled lamp flashing system 10 includes microprocessors in each of the individual strobe fixtures 14, and therefore these assemblies require only time base, intensity and duration, and address information which can be easily sent over a serial data link.

Referring now to Figure 2, strobe fixture 14 is illustrated mounted on a conduit box 42. Fixture 14 generally comprises a housing 19 including a base portion 44 and a dome portion 46 mounted on the base 44. A board 48 includes the appropriate strobe circuit 50 (discussed below) for the fixture 14. The circuit is operably connected to a lamp 41 mounted within the dome portion 46 in proximity to a reflector 43. The lamp 41 is a commercially available xenon strobe lamp having a quartz tube.

Figures 3 and 4 illustrate the circuit generally designated 50, which is built on the line fired strobe concept. Strobe fixtures are dimmable by conventional means already known with this type of device. AC power source 18 supplies power to the circuit 50. AC power is f ed to a logic supply 54, a zero-cross detector 56, a silicon controlled rectifier (SCR) unit 58 and a high voltage boost regulator circuit 60. The zero-cross detector 56 feeds a zero-cross signal to a central processing unit (CPU) 62, which is a commercially available model 8751, and also to the high voltage boost regulator 60. The SCR unit 58 supplies high current to the lamp 41. The SCR unit 58 is a bridge rectifier comprised of four SCRIs instead of diodes, as has been used in past line fired strobes. The zero- cross detector 56 is a typical zero-cross detector that gives a short duration pulse, i.e., less than 1 millisecond, at the zero-cross. The logic supply 54 is a basic linear supply using a transformer, a bridge rectifier, a filter capacitor and a voltage regulator. The transformer is chosen so as to give an acceptable range of input voltage to the voltage regulator when the AC power source 18 is between 90 volts AC and 255 volts AC.

The main purpose of the high voltage boost regulator 60 is to supply 400 volts to a trigger circuit 64 and boost the voltage supply to the lamp 41 through a boost capacitor circuit 70 and boost gating circuit 72. The 400 volts will be supplied in response to the AC power source 18 being anywhere between 90 volts and 255 volts. This 400 volts is achieved in the regulator 60 by phase regulating the powerin to a voltage multiplier circuit 101 in the regulator - see Figure 4. A sampling of output from the voltage multiplier circuit 101 is divided and compared to a reference voltage. An op-amp 103 in the regulator 60 compares these two voltages and a resulting correction voltage is generated and fed into a phase control circuit in the regulator 60 comprising a ramp generator 105, that is synchronised to the zero-cross detector 56. The ramp generated is fed into one side of a comparator 107 and the correction voltage is fed into another side of the comparator 107. The output from comparator 107 is fed into another comparator 109 makes up a one shot circuit that puts out a short pulse to fire an optocoupler ill that in turn fires a pair of SCRIs 113 that are phase regulating the multiplier circuit 101. All of this comprises a servo loop to control voltage from the multiplier circuit 101 to strobe circuit 50.

The same one shot circuit 109 also sends an output signal to another optocoupler 115 which in turn is sent to CPU 62 so that CPU 62 can determine what the AC power supply voltage is. This is accomplished by measuring the delay between the zero-crossing signal and the one shot signal of the high voltage regulator 60. This time is used to determine what voltage the AC power input 18 actually is because at higher voltages, the time delay will be greater. once the CPU 62 has determined the voltage level, it can change the phase angle at which the main SCR unit 58, the boost gating circuit 72 and the trigger circuit 64 f ires the lamp 41, thus controlling the lamp intensity to compensate for higher voltages.

The 400 volts from regulator 60 is used to feed the trigger circuit 64 and to recharge a boost capacitor circuit 70. The trigger circuit 64 is well known but the RC time constant has been reduced to allow for faster firing, e.g. up to 120 flashes per second.

A boost capacitor 119 is recharged by the 400 volts via a pair of resistors 117 in the boost capacitor circuit 70. The time constant of these resistors 117 and capacitor 119 must be very low to allow the circuit 50 to fire at a 120 Hz rate. In the past, a boost capacitor was directly across the lamp. With the recharge circuit being so fast, there is a side effect of having too much current available through the resistors 117 to the lamp 41 to keep the lamp 41 conducting. This is overcome by adding a boost gating circuit 72 between the boost capacitor circuit 70 and lamp 41 to gate off circuit 70 from the lamp 41. This allows for a very fast recharge time of about 8 milliseconds without the above-mentioned side effect.

In operation, CPU 62 decides that lamp 41 should be fired at a certain intensity and duration. The CPU 62 decision is based on either data from the serial link 16, via EIA 422 link transceiver 76, or derived from its internal time bases and program. A personality dip switch 151 is used to determine where these intensity, duration and time base signals are derived from. The binary setting of personality dip switch 151 is read directly by CPU 62. The settings tell CPU 62 to look at the serial link 16 for the intensity, duration and time base signals or to generate them internally. The settings of personality dip switch 151 also tell the CPU 62 how to interpret the data on the serial link 16. This data can come in by way of several data protocols, e.g. DMX 512, Lightwave Research data f lash protocol.

When the CPU 62 is looking at the serial link 16 f or its data, an address dip switch 153 is used to determine which serial signals are for each f ixture 14. When CPU 62 is generating its own intensity, duration and time base signals, it also uses address dip switch 153 to determine these signals. The binary number that CPU 62 reads in from address dip switch 153 is a representation of the intensity, duration and time base that the CPU 62 will generate.

The intensity signals for lamp 41 must now be converted to a phase conduction angle of the AC power input 18. A longer conduction angle will provide a brighter f lash. The CPU 62 looks at information from the regulator 60 to determine what voltage the fixture 14 is connected to. It also looks at the zero-crossing detector 56 signals to determine the frequency of the AC power source. This is accomplished by measuring the length of time between zerocrossing signals. Once the voltage and frequency determination is made, the conduction angle for that intensity at that voltage and frequency is determined.

An internal timer in CPU 62 is started at zero-cross, i.e. whenever the zero-cross detector 56 f ires, the timer is set to time out at the proper starting point of the conduction angle. Once the timer times out, the SCR unit 58 and the boost gating circuit 72 are enabled. Nothing happens in the lamp 41 at this point. After a time delay of approximately 10 microseconds, the trigger circuit 64 is activated. The 10 microsecond timedelay gives the boost gating circuit 72 and SCR unit 58 time to become enabled. After the delay, trigger circuit 64 energizes trigger coil 121 to fire a high voltage pulse causing lamp 41 to become ionized. Energy from the capacitor 119 is discharged through the boost gating circuit 72 into the lamp 41 to start conduction. once the voltage on the boost capacitor 119 f alls below the voltage of the SCR unit 58, the SCR unit 58 becomes forward biased and begins conducting with a large amount of current, e.g. 200 amps peak. The current of SCR unit 58 causes the intense flash that is emitted by lamp 41. SCR unit 58 shuts off once the line voltage of the AC power source 18 causes the lamp current to fall below the holding current of SCR unit 58, which happens at approximately the next zero-crossing point.

The firing signals from CPU 62, which are delayed by 10 microseconds as mentioned above, are each sent through one shot circuits 141, 143, so they are AC coupled to SCR unit 58, boost gating circuit 72, and trigger circuit 64. The duration of the one shot circuits 141, 143 is approximately 100 microseconds. The first reason for this is so that the boost capacitor 119 and trigger circuit 64 can recharge while lamp 41 is f iring through SCR unit 58. The second reason is so that the lamp 41 cannot go into a runaway firing if one of the firing signals ever becomes stuck in the firing position.

Claims (12)

CLAIMS:

1. A microprocessor controlled flash lamp system comprising at least one lamp fixture; means for operating the fixture from an AC power input of between 90 volts and 255 volts without a configuration change; said means including a high voltage boost regulator circuit; and a CPU connected to receive input from the boost regulator circuit to determine the voltage that the fixture is connected to and also connected to receive input from the zero-cross detector to determine the frequency of the AC power supply by measuring the length of time between zero-cross signals.

2. A flash lamp system including a plurality of microprocessor controlled flash lamps comprising a CPU connected to fire the lamps at a certain intensity and duration, the CPU including internal time bases and a program, and being connected to receive data from a serial link, the CPU also being connected to read a binary setting of a first dip switch which instructs the CPU to read the serial link signal for intensity, duration and time base signals, and the CPU also internally generating intensity, duration and time base signals; and a second dip switch connected to determine which serial signals are for each lamp, the CPU being connected to read the second dip switch when the CPU internally generates its own intensity, duration and time base signals.

3. A microprocessor controlled flash lamp system comprising a CPU connected to generate firing signals to a lamp; a trigger circuit; a first one shot circuit to AC couple the CPU to the trigger circuit; an SCR circuit; a boost gating circuit; and a second one shot circuit to AC couple the CPU to both the boost gating circuit and the SCR circuit, whereby the lamp is protected by both one shot circuits from a runaway f iring in response to one of the firing signals being stuck in a firing state.

4. A microprocessor controlled flash lamp system, substantially as described herein with reference to the accompanying drawings.

X - 1:5 - Amendments to the claims have been filed as follows 1. An AC powered line fired strobe lamp system comprising a logic supply, a zero-cross detector, an SCR unit and a high voltage boost regulator connected to receive the AC power, the zero-cross detector being connected to feed a zero-cross signal to a CPU to f ire the lamp at a certain intensity and duration, the SCR unit being connected to supply current to the lamp and the logic supply capable of accepting a range of input voltage when AC power supplied is between 90 volts and 255 volts.

2.

A strobe system according to claim 1, wherein the high voltage boost regulator is adapted to supply enhanced voltage, greater than the AC power supply voltage, to a trigger circuit and boosts the voltage supply to the lamp through a boost capacitor circuit and a boost gating circuit.

3. A strobe system according to claim 2, wherein the voltage from the high voltage boost regulator feeds the trigger circuit and recharges the boost capacitor circuit, the trigger circuit including a reduced time constant recharge circuit to permit faster firing, the boost gating circuit being between the boost capacitor circuit and the lamp to gate off the boost capacitor from the lamp allowing for an enhanced recharge time and limiting the current available to the lamp through the boost capacitor circuit.

4. A strobe system according to claim 2 or 3, wherein the enhanced voltage is achieved in the high voltage boost regulator by phase regulating the AC power to the boost regulator.

1 A 3 _f 4. -

5. A strobe system according to claim 4, wherein the phase regulated AC power to the high voltage boost regulator produces a one shot signal to the CPU which permits the CPU to determine the AC voltage by measuring a time delay between the zero-crossing signal and the one shot signal.

6. A strobe system according to claim 5, wherein, when the CPU has determined the AC voltage, the CPU changes a phase conduction angle at which the SCR unit, the boost gating circuit and the trigger circuit fire the lamp, whereby lamp intensity is controlled.

7. A strobe system according to claim 6, wherein the CPU includes an internal timer which is started when the zero-cross detector fires, whereby the timer is set to time out at the starting point of the phase conduction angle and the SCR unit and the boost gating circuit are enabled, and whereby after a time delay, the trigger circuit is activated.

8. A strobe system according to claim 1, wherein the zero-cross detector in connected to feed zero-cross signals to the CPU and also to the high voltage boost regulator, the CPU being connected to receive input from the high voltage boost regulator to determine the voltage at the AC input and also connected to receive input from the zero-cross detector to determine the frequency of the AC power by measuring the length of time between the zero-cross signals,' whereby when the voltage and frequency are determined, a phase conduction angle for that intensity at that voltage and frequency, is determined.

- 1,!5 -- is

9. A strobe system according to any one of the preceding claims, wherein the CPU includes time bases and a program, the CPU being connected to receive data from a serial link, the CPU also being connected to read a binary setting of an operating mode dip switch which instructs the CPU to read the serial link for intensity, duration and time base signals, and depending on the setting of the operating mode dip switch, the CPU also internally generates intensity, duration and time base signals.

10. A strobe system according to claim 9, wherein an address dip switch is connected to supply a binary signal to the CPU to determine a serial signal for each lamp when the CPU is looking at the serial link for data, and depending on the setting of the operating mode dip switch, when the CPU generates its own intensity, duration and time base signals.

11. A strobe system according to claim 1, wherein the high voltage boost regulator is adapted to supply enhanced voltage, greater than the AC power supplied voltage, to a trigger circuit and boosts the voltage supply to the lamp through a boost capacitor and a boost gating circuit, and wherein delayed firing signals from the CPU, resulting from zero- cross detector firing signals, are sent through a pair of one shot circuits AC coupled to the SCR unit, the boost gating circuit and the trigger circuit.

12. An AC powered line fired strobe lamp system, substantially as described herein with reference to the accompanying drawings.