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R501 Bluel GREEN! United States Patent ' on 3,585,280 [72] Inventor Renville 11.. McMann, Jr. [56] References Cited New Canaan, Colo. [211' Appl. No. 832,404 UNITED STATES PATENTS [22] Filed June 11, 1969 3,479,447 11/1969 Goldmark et al. .......... .. 178/52 [45] Patented June 15, I971 Primary Examiner—-Robert L. Richardson [731 Assignee Columbia Broadcasting System. Inc. Attorney-Brumbaugh, Graves. Donohue 62 Raymond New York, N.Y. ‘ABSTRACT: In the illustrative embodiment of the invention described herein, the superimposed pilot signal of a color in formation signal is supplied to a detector which produces a [54] GAIN CORRECTION APPARATUS FOR COLOR pulse each time the pilot signal crosses its zero axis. The pulses PICTURE INFORMATION SIGNALS are delayed in time to align the pulses with the pilot signal at REPRODUCED FROM A RECORD MEDIUM 90° from the axis crossing points and the delayed pulses are 5 Claims, 1 Drawing Fig. thereafter utilized to enable a sampling gate to which the pilot signal is also supplied. The output signal from the gate is [52] U.S. CI ...................................................... .. l78/5.2, smoothed and then supplied across a potentiometer to a varia 178/5.4 ble gain ampli?er to which the color carrier signal com [51] Int. Cl. ...................................................... .. ll04n 9/48 ponents of the color information signal are supplied to [50] HField of Search .......................................... .. 178/5.2, eliminate amplitude ?uctuations in the color carrier signal 5.4, 5.2 A, 5.2 D, 7.2, 6.7, 6.7 A, 5.4 components. I’ — _ _ — _ _ _ _ “ . _ _ _ _ * _ * _ _ _ _ _’ _l 30—-i a /46 I l CHROMA VAR'A "E | | “U” D,“ A Y AMPLIFIERGAIN : l 32 4a 36 45 t I I 352 44 I snow I_ 35 \ GATE | I4 22\CHROMA l PILOT _L 42 | CAMERA I FILTER I’ : /49 I l 3713 38 40 "' | '75" “'8' I ZERO om: - QUARTER | [0 A CROSSING l ,6 I DETECTOR PERIOD DELAY | TELEVISION l |—Y— ~ — ~ — — - ~ —'— — — — — — — — — — — ——-' MOTION PICTURE CAMERA A I PROJECTOR I2 24 25 17- --I8 I 352 SYNCHRONIZATION _ GENERATOR 26 VIDEO 20 CONVERTER R501 BLUEl GREEN! 3,585,280 1 2 medium including a typical correction circuit therefore ar GAIN CORRECTION APPARATUS FOR COLOR PICTURE ranged according to the present invention. INFORMATION SIGNALS REPRODUCED FROM A RECORD MEDIUM DESCRIPTION OF THE PREFERRED EMBODIMENT BACKGROUND OF THE INVENTION In the illustrative apparatus for scanning color picture infor mation recorded on a record medium in a succession of This invention relates to apparatus for reproducing color frames, each frame having a portion carrying luminance pic picture information signals recorded in monochrome on a ture information and a portion carrying color picture informa record medium in a succession of frames and, more particu 10 tion, as shown in FIG. 1, there is provided a standard motion larly, to a new and improved correction circuit for correcting picture projector 10 which is adapted to operate at, for exam the color picture information signals reproduced by such ap ple, 24 frames per second with the usual three~two pulldown paratus. ' relationship. Preferably, the ?lm contained in the projector 10 In the pending patent application entitled “Color Film is one of the types described in the above~mentioned patent Recording and Reproducing Apparatus," Ser. No. 519,106, application entitled “Color Film Recording and Reproducing now abandoned assigned to the assignce of the present inven Apparatus,"Ser. No. 5l9,l06. ‘ tion, there is described apparatus for recording luminance in Generally, one type ?lm comprises a succession of frames formation in one frame portion of a ?lm strip and coded color with each frame being divided into two adjacent parts contain information in a separate frame portion of the same ?lm strip. ing luminance and color information respectively, from a sin The luminance information may be in pictorial form and the 20 gle frame of an original color motion picture ?lm. The color information takes the form of a record including a ?rst brightness may be recorded optically or electronically with the carrier signal component modulated in phase and amplitude top to bottom dimension of the picture extending in the according to the color saturation and hue in the original scene direction of movement by the ?lm strip. The color information and a superimposed pilot signal occurring at one-half the color preferably comprises a succession of parallel lines which ex carrier signal frequency. Also described in the application is 25 tend transversely of the ?lm and spaced longitudinally thereof apparatus for scanning the information recorded on the with each line comprising a record of the modulation side above-described‘ type ?lm strip to produce signals represent bands of a suppressed color carrier signal modulated as a func ing brightness and color. Generally, the apparatus includes a tion of the color information in the picture. Also recorded in pair of cameras which are responsive to the light transmitted each line is a pilot signal which is adapted to be utilized sub through the two frame portions, respectively, for developing a sequently during playback to provide a carrier for extraction luminance signal and a chrominance signal, the chrominance of the color information contained in the color modulation signal including the modulated ?rst carrier signal component and the pilot signal. > sidebands. Preferably, the pilot signal frequency is outside the frequency band occupied by the color sidebands and it may be On occasion, the pictures reproduced from the signals 35 one-half the color carrier frequency. developed by the above-described apparatus contain un The projector 10 directs an image of the recorded informa desirable ?icker. The reason for the ?icker is that there is a tion to a beam splitter which comprises a half mirror 12 and a certain amount of signal retention by the camera handling the full mirror 14. One-half the light from the projector 10 passes chrominance information so that a preceding ?eld produces a signal having an effect which tends to amplitude modulate the through the half mirror 12 to a standard vidicon camera 16 which may be operated under standard television broadcast~ next chrominance ?eld signal. Both the modulated ?rst carrier signal component and the pilot signal are amplitude modu ing conditions, namely, at a horizontal line rate of 15,734 lines lated because of this signal carryover. per second,- and at a vertical frame rate of 29.97 frames per second. To this end, the camera 16 is supplied with suitable SUMMARY OF THE INVENTION horizontal and vertical de?ection and blanking signals over 45 the conductors l7 and 18 from a synchronization generator Accordingly, it is an object of the present invention to pro 20. The other one-half the light from the projector 10 is vide a correction circuit which overcomes the above-men re?ected from the mirror 12 to the mirror 14 and from the tioned problem of ?icker in the pictures reproduced from the latter to another standard monochrome television camera 22. chrominance signals developed by apparatus of the above A pair of branch conductors 17a and 18a of the conductors l7 described type. 50 and 18 supply synchronizing and blanking voltage signals to This and other objects are accomplished by the correction the camera 22 from the synchronization generator 20. apparatus of the present invention. The correction apparatus The brightness picture signal output (Y) from the television comprises a pair of ?lters for dividing the modulated ?rst car camera 16 is supplied through an ampli?er 24 and via a con rier signal and the pilot signal into separate channels and a de ductor 25 to a video converter 26 which may be of the type tector circuit which detects predetermined amplitude varia described in the above-mentioned patent application and ac tions in the pilot signal to produce correction pulses. Also in cordingly, decodes the chrominance signals and encodes the cluded is a delay circuit for delaying the correction pulses for decoded chrominance signals with the luminance signal to a predetermined period of time with respect to the pilot signal produce red, blue and green color component signals. and a gate circuit which is responsive to the pilot signal and to The chrominance signal output from the camera 22 with the the delayed correction pulses for transmitting selective por superimposed pilot signal is similarly ampli?ed by an ampli?er tions of the pilot signal. The selectively transmitted portions of 28 and supplied to a color picture information signal cor the pilot signal are thereafter utilized as gain control signals to rection circuit 30 which is arranged according to the present vary the amplitude of the ?rst modulated carrier signal to invention. As above mentioned, the chrominance signal con eliminate therefrom the ?icker producing amplitude modula tion. 65 tains the color carrier modulation sidebands and the superim~ posed pilot signal preferably has a frequency which is one-half In a preferred embodiment of the invention, the detector the frequency of the color ‘carrier modulation sideband com circuit comprises a zero-crossing detector and a potentiome ponents. Also, because of the inherent memory of the camera ter is provided to vary the amplitude of the transmitted por tions of thepilot signal. 22, the chrominance signal and the pilot signal will, on occa sion, be amplitude modulated. The modulation in the BRIEF DESCRIPTION OF THE DRAWINGS chrominance signal will produce ?icker in a reproduced pic~ ture. In the drawing: In the correction circuit 30, the color picture information The F IGUREis a schematic block diagram of a system for . signal is supplied concurrently to a chroma ?lter 32 and a pilot reproducing color picture information signals from a record 75 ?lter 34 which separate the chrominance and pilot signals.
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