BUILT-IN DISSOLVE UNIT FOR SLIDE PROJECTORS

Abstract: A multiple projector control system for synchronizing the operation of the advance mechanisms of said projectors (201, 202) with an audio program by means of projector change pulses (1007, 1008) recorded on a track of a magnetic tape and an audio program recorded on the same track on the tape. In addition, on the same track of the tape is a signal (1005, 1006) to control the intensity of the lamp in each projector to provide a fade-in fade-out projection from each projector.

Description: BUILT-IN DISSOLVE UNIT FOR SLIDE PROJECTORS Background of the Invention Automatic and manual dissolve systems for photographic slide projectors are presently in use today, however, all of said systems are external control units, using complex electronics. In addition they are limited in the functions they offer, namely slide change, continuous dissolve facilities with variable speed or fixed speed and fixed sequence, super imposed or flash options and have the drawback of requiring complex electrical connections. The objections of the present invention is to el minate the drawbacks of the prior art and to provide a system that has: 1. Simple interconnections with respect to tape or cassette recorders, and the dissolve unit contained within one of the projectors. 2. Automatic operation without the need of expensive recorders by recording all needed information on one track of a tape. 3. Means to allow exchanging programmed cassettes. 4. Means to allow interrupting the programming or playback mode without causing distortion or bad synchronization. 5. Means during dissolve to maintain the total light intensity of the projectors at a constant. 6. Inexpensive and simple testing and assembling requirements. It is a further object of this invention to provide an improved system allowing the slide change operation and lamp OMPI • fa WIPO intensity control of a photographic slide projector kit to composed signals reproduced by a sound apparatus, in particular by a tape-recorder or cassette-recorder. SUMMARY OF THE INVENTION A built-in dissolve system for photographic projectors having a control system in which a complex signal produced for recording on a single track of a recording medium can be used to independently control the image advance and total light intensity of the photographic projectors. A second signal of different frequency but of the same magnitude recorded on a second track of the same recording medium is used for controlling an audio system for said projectors. This allows good channel separation on normal consumer recording devices using a frequence based less than 2K Hz. The complex signal which is placed on the tape or cassette recorders is placed on said tape or cassette by means of a "voltage controlled oscillator", obtaining a triangle signal. This signal is recorded on tape and is also fed to a "frequence to voltage converter" obtaining a voltage corresponding to a frequence. In addition to the automatic dissolve system the control system has manual override capability that operates the audio, advance and dissolve of each project by hand-held remote control means. This override capability may be used for both total operation or to interrupt the automatic system without effecting the automatic sequence of the playback or dissolve. Both the automatic and the manual dissolve control system is designed to maintain the total light intensity of all the projectors at a constant during the dissolve function even though the characteristics of the lamps in the projectors are non-linear with respect to the voltage change which is in effect during the dissolve function. OMPI Brief Description of the Drawings Fig. 1 is a basic block diagram of the system minus the projectors. Fig. 2A is a schematic diagram of part of the system. Fig. 2B is a schematic diagram of the rest of the system. Fig. 3 is a block diagram of two projectors with remote control attached to the projectors. Description of a Preferred Embodiment Referring now to the drawings in detail, Fig. 3 shows conventional projector 202 electrically attached to projector 201. Projector 201 in addition to having standard features of a slide projector, contains electrical circuiting for built-in synchronization of audio and projection as well as built-in projection dissolve circuitry as shown in detail in Fig. 2. Also shown in Fig. 3 is standard remote control unit 203 for manual override of the automatic synchronization and dissolve circuitry shown in Fig. 2. Turning now to Fig. 2 the following is a detailed description of each individual component of Fig. 2 and how it interacts with the other components of Fig. 2 to create signals for operating the conventional electric circuit of the standard projector 202 and that portion of projector 201 that is standard in order that said projectors are able to project images on screen 204 in proper sequence and in synchronization with an audio program so that as one image fades out on screen 204 another image is fading in on said screen 204 and whereby the total intensity of light 205 from projector 201 and 202 is a constant. The current layout of Fig. 2 follows the layout of the block diagram of Fig. 1. Block 1001 corresponds with the remote control device. Block 1002 corresponds with the VCO: voltage controlled oscillator. Block 1003 corresponds with the F/V: frequence to voltage converter. Block 1004 corresponds with the complementer. Blocks 1005 & 1006 correspond with fase control systems for lamp intensity control. Blocks 1007, 1008, 1009 correspond with the zero detector and control systems for slide change. Block 1010 is the main supply. The remote control device 1001 consisting out of: resistors 121, 122, 123, 124, 127, 129, 130, 131, 133, 126 and switches 132, 123, 128 provides dissolve. The input signal for VCO 1002 allowing dissolve and slide change possibilties. The voltage controlled oscillator 1002, consisting out of: integrated circuit 11, the reference voltage obtaining by resistor 5 and voltage reference diode 6 and further the frequence determining part, resistor 8, 9, 4, 7, 12. The variable output signal is obtained by resistors 13, 15, 17, 16 and decoupling capacitor 14, produces an AC signal with a determined frequence spectrum for instance from 200 Hz to 1400 Hz. Switch 20A provides the play and playback mode. he frequence to voltage converter 1003, consisting out of integrated circuit 23; timing components; capacitors 18, 20 and resistors 21, 22; and biasing resistor 24, converts the frequence to a DC voltage, suitable for further manipulation. The complementer 1004 consisting out of integrated circuit 34 in conjection with resistors 28, 27, 29, 30, 33 31, 32 produces the inverted signal. The control systems 1007, 1008 consisting out of, respectively: Integrated circuit 85; resistors 89, 91, 88, 86, 84, 82, 81; capacitor 87; transistors 83, 80, diodes 79, 90 and integrated circuit 113; resistors 112, 111, 114, 115, 116, 118, 119; capacitor 110; transistors 117A, 117, 78; diode 106 provide slide change for the corresponding slide projectors. Block 1009 consisting out of integrated circuits 98, 101; resistors 99, 100, 97, 95, 96, 102, 104, 107, 94, 92; diodes 96, 105; capacitors 93, 106 disables the control devices 1007, 1008 when there is any input signal from the recording device. The control systems 1005, 1006 consisting out of respectively integrated circuits: Differential amplifiers 42, 66, zero cross detectors 35, 68; ramp generators 46, 60; output stage amplifiers 49, 57; in conjunction with timing capacitors 40, 67; trigger impulse capacitors 45, 61; timing resistors 38, 39, 71, 70; trigger impulse resistors 44, 43, 62, 63 and biasing resistors 36, 41, 47, 48, 50, 52, 69, 64, 59, 58, 56, 55 providing lamp intensity control, this in conjection with power triacs 51, 53. The circuit 1010 consisting out of transformer 148; integrated voltage regulator 145; capacitors 138, 143, 144, 139, 146; rectifier diodes 142, 138 provides the desired AC and DC voltages for operating the total circuitry. The above different circuits receive from each other the following impulses to control the fade-in fade-out feature, the synchronizing of slide change with audio, as well as maintaining light intensity. In addition each of the following components have the following capacities. In view of the above, the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification as indicating the scope of the invention. OMPI _ 'A,f- IPO

Claims: WE CLAIM : 1. Apparatus for providing a composite signal for recording on a single track of a recording medium, said composite signal being comprised of slide change and lamp intensity and audio control signals for multiple projector and comprising a slide changing mechanism and a projection lamp for alternatively projecting images onto a common screen area, a programming device contained within only one of said projectors producing slide changeover pulses synchronized with audio output signals, pulse controlled means operatively connected to said slide changing mechanisms for operation thereof in response to said changeover pulses, means operatively connected to said projection lamps for simultaneously dimming one of the lamps and illuminating the other of the lamps during a changeover cycle of the pulse controlled means, dissolve control means responsive to the duration of said pulses for controlling the time interval during which said lamps are respectively dimmed toward extinction and illuminated toward maximum brilliance while maintaining a total illumination on the common screen at a constant. 2. Apparatus according to Claim 1 wherein one of the projectors has electrically connected to it a remote control means for overriding programming device without interrupting the sequence of the dissolve and audio program.

Inventors: DE PRIJCKER W, DE SMET E, DE SMET L
Applicants: GAF CORP
Application year: 1981
Main classification: G03B31
IPC codes: G03B23, G03B31