United States Patent [191 [11] Patent Number: 4,477,841 Chen et al. [45] Date of Patent: Oct. 16, 1984 [54] VIDEO PLAYER WITH CAPTION [56] References Cited GENERATOR HAVING CHARACTER BACKGROUND PROVISIONS U'S' PATENT DOCUMENTS 3,984,828 10/1976 Beyers, Jr. ................. .. 340/324 AD 4,122,488 10/1978 Mikado ............................... .. 358/l9 [75} Inventors: Thomas Y. Chen, East Brunswick; . Walter G. Gibson’ Princeton’ both of Przmary Exammer——Raymond F. Cardrllo, Jr. Ni Attorney, Agent, or Firm-E. M. whitacre; P. J. Rasmussen; R. G. Coalter [73] Assignee: RCA Corporation, New York, N.Y. [57] ABSTRACT A ?lter limits the bandwidth of a caption video signal in a video disc player to minimize color beats when the [21] APPL N04 309,192 caption signal is displayed along with a picture video signal on a television receiver. The ?lter delay, which . _ would otherwise cause offset between the caption and [22] Flled' Oct‘ 6’ 1981 an associated background signal used to enhance visibil ity of the caption, is compensated for by extending the [51] Int. Cl.3 ............................................. .. H04N 5/76 time duration of each occurrence of the background [52] US. Cl. ................................... .. 358/335; 358/342 signal by a multiple of the ?lter delay. [58] Field of Search .............................. .. 358/335—348, 358/310-334; 360/331, 37.1 9 Claims, 7 Drawing Figures 011i I6 18 $20 l0* '2 D AUDIO/VIDEO a TV ‘ I4 I PROCESSOR —S|> MODULATOR <~—s2 26~ I so ~28 30 i DATA 5 INFORMATION STATUS MICROPROCESSOR SWITCH 34 BUFFER - CONTROLLER UNIT I VIDEO BLANKING S4 —>s5 ’ ii 60 _ ACT F“; GENERATOR 50 CAPTION VIDEO l Lcw__ ‘T56 F“ PASS 80 FILTER W &s{ s93 #N’w VIDEO SWITCH COMPOSITE VIDEO» - 32 US. Patent Oct. 16, 1984 4,477,841 JET l6 l8\ <r~20 l0» '2 D ~AUDI0/VIDE0 » TV ‘ l4 PROCESSOR 3T- MODULATOR <W———S2 26* I 3208 E ’“ 30 L DATA | 5 INFORMATION W M|CROPROCESSOR+SWITCH 34 BUFFER 5' U§ CONTROLLER UNIT 4’ lvmEo BLANKING ““ TIMINGUNIT “'58 2 25"" 434 60 —*s5 ' “ lg] EvI DIGITALDISPLAY : CHARACTER FH; GENERATOR 50 CAPTION VIDEO | ‘j- ‘ Low 56 F" FILTERPASS ——5\60 I H, 4,5; 70 391... 4N” vmEoswncN COMPOSITE VIDEO» ' 22 oNE TIMING “X54 NNN 1-1 _I F"! F‘! r“: I“ BACKGROUND ‘ r - -_ SIGNALS? CENT‘ERED CAPTION C - SIGNAL,56VIDEO TWOPIXELé I Fig-2. HLTEREDCAPUOND ‘- l2 PIXEL FILTER DELAY EXTENDED I 4 BACKGROUNDS|GNAL,S8 _ M PIXEL EXTENSION TIMINGSIGNAL s3 57 EXTENSION BACKGROUND " BACKGROUND IN OUT 4,477,841 ll 2 harmonics of the wideband caption video signal falling VIDEO PLAYER WITH CAPTION GENERATOR within the chrominance signal passband of the receiver. HAVING CHARACTER BACKGROUND If one were aware of this new problem and also of its PROVISIONS probable cause, one might consider limiting the caption 5 video signal bandwidth by suitable means, for example, This invention relates to video players and particu such as a low pass ?lter. This can lead to yet another larly to video disc or tape players of the type having a problem. Speci?cally, limiting the bandwidth of the caption generator for producing numeric or alphanu caption video signal will result in a delay relative to the meric characters for simultaneous display along with a background signal which will cause the background recovered “picture" signal on the screen of a raster scan signal to be asymmetrical with respect to the character display device such as a video monitor or television pixels when displayed on the television‘ receiver. An receiver and in which the character visibility is en- _ other possibility would be to separately ?lter the back hanced by means of background shading or bordering. ground and the caption signals but this approach is In video disc or tape players, particularly of the re unsatisfactory because it requires two ?lters and it may motely controlled variety, it is desirable to provide a 15 degrade the performance of the video switch (con display of information such as playing time, video frame trolled by the background signal) which provides the numbers or other information recovered from the tape function of interleaving (time division multiplexing) the or disc or otherwise generated within the player. One caption and picture video signals. Yet‘another solution approach that may be utilized involves displaying the which might be considered would be to ?lter the inter information as numeric or alphanumeric characters on 20 leaved captionand picture signals. This, however, can the screen of a television receiver or monitor, Where lead to a loss of resolution of the picture signal which is the character information is displayed simultaneously undesirable. with a “picture” recovered from the record medium Accordingly, it is an object of the present invention (tape or disc), the resultant image may be subject to to provide a video player apparatus in which the prob appearing washed out when a character is generated in lem of cross color or color beats is substantially reduced a region of the displayed picture image having bright and in which the caption character of a displayed image ness and/or color similar to that of the displayed char remains symmetrically disposed within a background area of contrasting brightness. acter. It is known that one may enhance the visibility of A video disc player embodying the invention in captions displayed simultaneously with a picture by 30 cludes signal recovery means for providing a composite video signal and character generator means for provid providing a contrasting background in the immediate ing a caption video signal and a caption background region of the caption. Such a background may be in the signal. A ?lter means, coupled to the generator means form of a “box” which completely surrounds each char and having a characteristic delay, limits the bandwidth acter or character grouping or it may be in the form of 35 of the caption video signal to a predetermined value. A shading or edging of each individual character. As an circuit means, coupled to the generator means, extends example,'in US. Pat. No. 3,984,828 of Beyers Jr., a . the background signal for a predetermined time subse character generator is shown in a television receiver quent to each occurrence thereof, the predetermined application wherein a caption background signal and a time corresponding to a multiple'of the characteristic caption video signal are generatedhThe-‘caption video 40 delay. Switch means, responsive to the extended back signal is added to the picture video signal for display on ground signal, ‘ combines the composite video signal a kinescope and the background signal (symmetrically ' with the bandwidth limited caption video signal in in disposed with respect to borders of the caption video terleaved fashion to form a resultant signal for applica signal) is used for blanking of the picture video signal tion to an output means. " whereby caption characters having contrasting black 45 In the drawings: borders appear in the displayed picture. FIG. 1 is a block diagram of a video disc player em The present invention resides in part in recognition of - bodying the invention; ‘ a new problem which can arise in video disc or tape FIG. 2, consisting of A-E, is a waveform diagram players having caption generators which provide con~ illustrating certain aspects of operation of the player of trasting background (shading or boxing) for enhancing 50 FIG. 1; and ' the visibility of characters displayed with a recovered FIG. 3 is a diagram of a character background exten composite (picture) video signal. More speci?cally, der logic circuit suitable for use in the player of FIG. 1. conventional character generators are digital devices The player 10 of FIG. 1 includes a turntable mecha which produce character dots or picture elements (pix nism for rotating a video disc record 12 at'a predeter7 els) having edges with very fast rise times as compared 55 mined substantially constant angular velocity and a with a composite “picture” video signal. The process in ' pickup transducer 14 for recovering information signals a video player of interleaving the wide bandwidth cap from the disc. Illustratively,iit will be assumed that the tion signal with the narrower bandwidth video signal by player is intended for use with records in which infor time division multiplexing, modulating an RF carrier mation is stored in the form of topological variations with the resultant signal and then demodulating the RF 60 and recovered by sensing capacitance variations be carrier in a TV receiver can result in objectional “cross tween a stylus in transducer 14 and the record 12. The color" or “color beat” effects in the displayed image. output of transducer 14 is applied to a capacitance-to This problem is not likely to occur where the caption voltage converter in player 10 which produces an FM generator is in a television receiver because the com output signal voltage representative of the recorded bined or multiplexed signal format does not exist and 65 information. Such ‘records and suitable circuits‘for im the caption does not pass through the color demodula plementing capacitance-to-voltage conversion are well tor, the caption being applied to the kinescope directly. known. See, for example, US. Pat. No. 3,783,196 enti It is believed that the cross color effect may be due to tled “HIGH DENSITY CAPACITIVE INFORMA 4,477,841 3 4 TION RECORDS AND PLAYBACK APPARATUS stylus lift signal activates a stylus lifter solenoid in THEREFORE” which issued to T. 0. Stanley, Jan. 1, player 10 which lifts the stylus in transducer 14 from 1974; US. Pat. No. 3,842,194 entitled “INFORMA record 12 to avoid unnecessary wear. The squelch sig TION RECORDS .