Control for synchronizing projectors with an audio program

Claim 2

A control unit for controlling a plurality of slide projectors, each having a lamp, a blower and a slide change mechanism, in response to slide change pulses and an off pulse recorded on a magnetic tape and wherein the control unit is constructed to be connected to the projectors and to the output of a playback recorder which plays the tape, said control unit comprising, frequency sensing means for sensing each slide change pulse and the off pulse, a plurality of slide change relay means, each operatively associated with the frequency sensing means for actuating the slide change mechanism of a particular projector in response to the sensing of a slide change pulse having a frequency corresponding to that projector, lamp relay means operatively associated with the frequency sensing means for shutting off all of the projector lamps immediately on the sensing of the off pulse, blower relay means operatively associated with the frequency sensing means for shutting off all of the blowers on the sensing of the off pulse, time delay means for delaying the actuation of the blower relay means for a fixed period of time after the sensing of the shutoff pulse to permit the blowers to cool the projector lamps, and a line voltage relay means operatively associated with the blower relay mEans and wherein the time delay means includes a holding circuit which holds the line voltage relay closed for said fixed period of time.

Claim 3

The invention claimed in 1 wherein the holding circuit includes a capacitor and the size of the capacitor determines the duration of said fixed period of time.

Claim 4

A control unit for controlling a plurality of slide projectors, each having a lamp, a blower and a slide change mechanism, in response to slide change pulses and an off pulse recorded on a magnetic tape and wherein the control unit is constructed to be connected to the projectors and to the output of a playback recorder which plays the tape, said control unit comprising, frequency sensing means for sensing each slide change pulse and the off pulse, a plurality of slide change relay means, each operatively associated with the frequency sensing means for actuating the slide change mechanism of a particular projector in response to the sensing of a slide change pulse having a frequency corresponding to that projector, lamp relay means operatively associated with the frequency sensing means for shutting off all of the projector lamps immediately on the sensing of the off pulse, blower relay means operatively associated with the frequency sensing means for shutting off all of the blowers on the sensing of the off pulse, and a line voltage relay means operatively associated with all of said other relays to shut down all circuits in said control unit in the event of a power failure.

Claim 5

A control unit for controlling a plurality of slide projectors, each having a lamp, a blower and a slide change mechanism, in response to slide change pulses and an off pulse recorded on a magnetic tape and wherein the control unit is constructed to be connected to the projectors and to the output of a playback recorder which plays the tape, said control unit comprising, frequency sensing means for sensing each slide change pulse and the off pulse, a plurality of slide change relay means, each operatively associated with the frequency sensing means for actuating the slide change mechanism of a particular projector in response to the sensing of a slide change pulse having a frequency corresponding to that projector, lamp relay means operatively associated with the frequency sensing means for shutting off all of the projector lamps immediately on the sensing of the off pulse, blower relay means operatively associated with the frequency sensing means for shutting off all of the blowers on the sensing of the off pulse, and a line voltage relay means operatively associated with all of said other relays to shut down all circuits in said control unit in the event of a power failure.

Claim 6

A control unit for controlling a plurality of slide projectors, each having a lamp, a blower and a slide change mechanism, in response to slide change pulses and an off pulse recorded on a magnetic tape and wherein the control unit is constructed to be connected to the projectors and to the output of a playback recorder which plays the tape, said control unit comprising, frequency sensing means for sensing each slide change pulse and the off pulse, a plurality of slide change relay means, each operatively associated with the frequency sensing means for actuating the slide change mechanism of a particular projector in response to the sensing of a slide change pulse having a frequency corresponding to that projector, lamp relay means operatively associated with the frequency sensing means for shutting off all of the projector lamps immediately on the sensing of the off pulse, blower relay means operatively associated with the frequency sensing means for shutting off all of the blowers on the sensing of the off pulse, and off pulse relay means operatively associated with the lamp relay means and the blower relay means for shutting off the lamp and blower on the sensing of the off pulse and wherein the frequency for the slide change pulse of one particular projector is a master pulse frequency and the frequency sensing means for that frequency are operatively associated with off pulse relay to trigger the off pulse relay in the event the volume level of the master pulse frequency is too high.

Claim 7

A control unit for controlling a plurality of slide projectors, each having a lamp, a blower and a slide change mechanism, in response to slide change pulses and an off pulse recorded on a magnetic tape and wherein the control unit is constructed to be connected to the projectors and to the output of a playback recorder which plays the tape, said control unit comprising, frequency sensing means for sensing each slide change pulse and the off pulse, a plurality of slide change relay means, each operatively associated with the frequency sensing means for actuating the slide change mechanism of a particular projector in response to the sensing of a slide change pulse having a frequency corresponding to that projector, lamp relay means operatively associated with the frequency sensing means for shutting off all of the projector lamps immediately on the sensing of the off pulse, blower relay means operatively associated with the frequency sensing means for shutting off all of the blowers on the sensing of the off pulse, and off pulse relay means operatively associated with the lamp relay means and the blower relay means for shutting off the lamp and blower on the sensing of the off pulse and wherein the frequency for the slide change pulse of one particular projector is a master pulse frequency and the frequency sensing means for that frequency are operatively associated with off pulse relay to trigger the off pulse relay in the event the volume level of the master pulse frequency is too high.

Claim 8

A control unit for controlling a plurality of slide projectors, each having a lamp, a blower and a slide change mechanism, in response to slide change pulses and an off pulse recorded on a magnetic tape and wherein the control unit is constructed to be connected to the projectors and to the output of a playback recorder which plays the tape, said control unit comprising, frequency sensing means for sensing each slide change pulse and the off pulse, a plurality of slide change relay means, each operatively associated with the frequency sensing means for actuating the slide change mechanism of a particular projector in response to the sensing of a slide change pulse having a frequency corresponding to that projector, lamp relay means operatively associated with the frequency sensing means for shutting off all of the projector lamps immediately on the sensing of the off pulse, blower relay means operatively associated with the frequency sensing means for shutting off all of the blowers on the sensing of the off pulse, and a start switch which is momentarily depressed to turn on the control unit by connecting the control unit to a power supply, a line holding relay means for holding the line voltage on, a holding circuit relay means for the line holding relay means and a momentary relay means effective to provide momentary connection of voltage to the terminals of the holding relay means on depression of the start switch to eliminate the need for line voltage and dc relay voltage to share the same start switch.

Claim 9

A control unit for controlling a plurality of slide projectors, each having a lamp, a blower and a slide change mechanism, in response to slide change pulses and an off pulse recorded on a magnetic tape and wherein the control unit is constructed to be connected to the projectors and to the output of a playback recorder which plays the tape, said control unit comprising, frequency sensing means for sensing each slide change pulse and the off pulse, a plurality of slide change relay means, each operatively associated with the frequency sensing means for actuating the slide change mechanism of a particular projector in response to the sensing of a slide change pulse having a frequency corresponding to that projector, lamp relay means operatively associated with the frequency sensing means for shutting off all of the projector lamps immediately on the sensing of the off pulse, blower relay means operatively associated with the frequency sensing means for shutting off all of the blowers on the sensing of the off pulse, and a start switch which is momentarily depressed to turn on the control unit by connecting the control unit to a power supply, a line holding relay means for holding the line voltage on, a holding circuit relay means for the line holding relay means and a momentary relay means effective to provide momentary connection of voltage to the terminals of the holding relay means on depression of the start switch to eliminate the need for line voltage and dc relay voltage to share the same start switch.

Claim 10

The invention defined in claim 5 including a capacitor connected to the momentary relay means for supplying current to the coil of the momentary relay means only until the capacitor is charged and for diverting current from the blower relay means until the capacitor is charged to provide a time delay which allows all relays to lock in place before the full load of the projectors drops the line voltage.

Claim 11

The invention defined in claim 6 wherein the line holding relay means close only if the initial line voltage is sufficiently high to switch the line holding relay means during the time delay provided by said capacitor so that said control unit will not start operation with too low line voltage.

Claim 12

The invention defined in claim 5 including a resistor between the power supply and the blower relay means in series with the power supply and the coil of the blower relay means and sufficiently large to hold the blower relay means on if the contacts of the momentary relay means are jarred during operation so that the blower relay means are held fully latched during such instants.

Claim 13

A control unit for controlling a plurality of slide projectors, each having a lamp, a blower and a slide change mechanism, in response to slide change pulses and an off pulse recorded on a magnetic tape and wherein the control unit is constructed to be connected to the projectors and to the output of a playback recorder which plays the tape, said control unit comprising, frequency sensing means for sensing each slide change pulse and the off pulse, a plurality of slide change relay means, each operatively associated with the frequency sensing means for actuating the slide change mechanism of a particular projector in response to the sensing of a slide change pulse having a frequency corresponding to that projector, lamp relay means operatively associated with the frequency sensing means for shutting off all of the projector lamps immediately on the sensing of the off pulse, blower relay means operatively associated with the frequency sensing means for shutting off all of the blowers on the sensing of the off pulse, time delay means for delaying the actuation of the blower relay means for a fixed period of time after the sensing of the shutoff pulse to permit the blowers to cool the projector lamps, and a line voltage relay means, a holding relay means operatively associated with the line voltage relay means for holding voltage to the line voltage relay means, off pulse relay means actuated on sensing of the off pulse and wherein the off pulse relay means are operatively associated with the holding relay means to actuate the lamp relay means to shut off the lamps by shorting across the coil of the holding relay means whereby the off pulse relay means need be only momentarily actuated and need not be continuously supplied with current.

Claim 14

A control unit for controlling a plurality of slide projectors, each having a lamp, a blower and a slide change mechanism, in response to slide change pulses and an off pulse recorded on a magnetic tape and wherein the control unit is constructed to be connected to the projectors and to the output of a playback recorder which plays the tape, said control unit comprising, frequency sensing means for sensing each slide change pulse and the off pulse, a plurality of slide change relay means, each operatively associated with the frequency sensing means for actuating the slide change mechanism of a particular projector in response to the sensing of a slide change pulse having a frequency corresponding to that projector, lamp relay means operatively associated with the frequency sensing means for shutting off all of the projector lamps immediately on the sensing of the off pulse, blower relay means operatively associated with the frequency sensing means for shutting off all of the blowers on the sensing of the off pulse, time delay means for delaying the actuation of the blower relay means for a fixed period of time after the sensing of the shutoff pulse to permit the blowers to cool the projector lamps, and a line voltage relay means, a holding relay means operatively associated with the line voltage relay means for holding voltage to the line voltage relay means, off pulse relay means actuated on sensing of the off pulse and wherein the off pulse relay means are operatively associated with the holding relay means to actuate the lamp relay means to shut off the lamps by shorting across the coil of the holding relay means whereby the off pulse relay means need be only momentarily actuated and need not be continuously supplied with current.

Claim 15

The invention defined in claim 9 including a resistor in series with the holding relay means for preventing damage to the power supply during shorting across the coil of the holding relay means.

Claim 16

The invention defined in claim 9 wherein the off pulse relay contacts are normally open and close only when the off pulse is sensed so that any shaking of the control unit cannot cause the contacts of the off pulse relay means to lose contact and to shut off the operation too soon.

Claim 17

The invention defined in claim 11 incLuding a capacitor in the off pulse relay means to prevent instantaneous, low frequency pulses lower than the frequency of the off pulse from accidentally shutting down the system.