Copy timing control circuit for double-deck video cassette recorder

Abstract: A copy timing control circuit capable of concurrently controlling a copy operation timing of one video deck by application of control signals supplied from a mode switch of the other video deck as well as a timing signal thereof. The copy timing control circuit used in a double-deck video cassette recorder having at least two video cassette decks capable of tape-to-tape copying of video data therebetween, is provided with a mode signal input means for receiving a plurality of mode selection signals produced by application of mode switches in either one of the video cassette decks, a copy signal input means for receiving a copy signal produced by application of a copy key, a microprocessor (15) operably connected to the mode signal input means and the copy signal input means for producing a servo control signal dependent upon receipt of a given state of the mode selection signals and the copy signal, and two servo motor drivers (5,10), connected to receive the servo control signal, for controlling the drive of the respective video cassette deck in response to the servo control signal.

Description: BACKGROUND OF THE INVENTION The present invention relates to a copy timing control circuit for use in a double-deck video cassette recorder (VCR), particularly to a timing control in a desired operation mode during execution of tape-to-tape copying operation in the VCRs. In case a tape-to-tape copying operation is carried out with a double-deck VCR or two VCRs connected to each other, one of a prior art requires to have one deck or one VCR set to a playback mode and other deck or VCR set to a record mode, when a video signal from the former deck in playback mode is recorded onto the latter deck in record mode. Such prior art however, has a drawback that a precise position control of tape upon copying between both decks or VCRs is hardly provided because of lack of synchronism therebetween. This drawback mostly results in not only waste of tape in using the copy mode, but also occurrence of discontinuity in recording or playback of video signal. Published US patent number US 4,792,867 discloses a dual deck video cassette recorder system having the features of the pre-characterising portion of Claim 1. SUMMARY OF THE INVENTION The present invention generally aims to provide a copy timing control circuit capable of concurrently controlling a copy operation timing of one video deck by application of control signals supplied from a mode switch of the other video deck as well as a timing signal thereof. According to a first preferred embodiment of the present invention, a copy timing control circuit in a double-deck video cassette recorder having at least a first video cassette deck and a second video cassette deck capable of tape-to-tape copying of video data therebetween, is provided with a mode signal input means for receiving first mode selection signals from said first video cassette deck and second mode selection signals from said second video cassette deck produced by application of mode switches in said respective video cassette decks, a copy signal input means for receiving a copy signal produced by application of a copy key, a control means operably connected to said mode signal input means and a said copy signal input means, for producing a servo control signal dependent upon receipt of a given state of said mode selection signals and said copy signal, and motor driving means, connected to receive said servo control signal, for controlling the drive of said other video cassette deck in response to said servo control signal; characterised in that said control means produces said servo control signal when said first mode selection signals are indicative of a record pause mode of said first video cassette deck and said second mode selection signals are indicative of a playback mode or a still mode of said second video cassette deck, and said control means is for producing said servo control signal to enable a record mode of said second video cassette deck in response to receipt of said copy signal when said first mode selection signals are indicative of a stop mode of said first video cassette deck. According to a second preferred embodiment of the present invention, a method for controlling a double-deck video cassette recorder having at least a first video cassette deck and a second video cassette deck capable of tape-to-tape copying of video data therebetween, said method comprising the steps of: receiving mode signal inputs of first mode selection signals from said first video cassette deck and second mode selection signals from said second video cassette deck produced by application of mode switches in said respective video cassette decks; receiving a copy signal input of a copy signal produced by application of a copy key, producing a servo control signal from a control means (15) operably connected to said mode signal input means and a said copy signal input means, said servo control signal being dependent upon receipt of a given state of said mode selection signals and said copy signal; and controlling the drive of said other video cassette deck by motor driving means (5 or 10), connected to receive said servo control signal, in response to said servo control signal; characterised in that said control means procedures said servo control signal when said first mode selection signals are indicative of a record pause mode of said first video cassette deck and said second mode selection signals are indicative of a playback mode or a still mode of said second video cassette deck, and said method includes the steps of producing said servo control signal to enable a record mode of said second video cassette deck in response to receipt of said copy signal when said first mode selection signals are indicative of a stop mode of said first video cassette deck. BRIEF DESCRIPTION OF THE DRAWINGS A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily enjoyed as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like members indicate the same or similar components, wherein: Figure 1 shows a block diagram of a preferred embodiment according to the present invention; Figures 2A and 2B respectively show by way of example input signals at respective mode switches A, B and C, and a schematic diagram, similar to a truth table, defining the various operation modes of a video cassette deck with respect to the input signals at the mode switches; and Figures 3 through 6 are various waveform diagrams to explain a part of the operation according to the present invention. DETAILED DESCRIPTION OF THE INVENTION Referring to Figure 1, a preferred embodiment of a copy timing control circuit according to the present invention is disclosed. The circuit is used in a double-deck video cassette recorder having at least two video cassette decks capable of tape-to-tape copy of video data therebetween, wherein the circuit includes a mode signal input means for receiving a plurality of mode selection signals produced by application of mode switches in either one of said video cassette decks. The circuit further includes a copy signal input means for receiving a copy signal produced by application of a copy key, and a microprocessor 15 operably connected to said mode signal input means and said copy signal input means, for producing a servo control signal dependent upon receipt of a given state of said mode selection signals and said copy signal. The circuit further includes two servo motor driver 5 and 10, connected to receive said servo control signal, for controlling the drive of said respective video cassette deck in response to said servo control signal. A mode selection logic signal as shown in Figure 2A, generated by the mode switch input according to operation modes of the deck, is applied to the microprocessor 15, which operation modes are shown in the diagram of Figure 2B. For example, if the mode switches A and B are at logic low state, while the mode switch C is at logic high state, then "EJECT" mode is selected. Likewise, if the mode switches A and C are at logic high state, while the mode switch B is at logic low state, then "PLAY", or "RECORD" mode is operated. Therefore, in order that the operation mode of deck is change from "EJECT" mode to "RECORD" or "PLAYBACK" mode, the input signals from the mode switches A, B and C, as shown in the diagram of Figure 2B, are applied to the microprocessor 15. Thereafter, the microprocessor checks whether to receive a copy key input, and when a desired mode selection signal is received from the mode switches in one cassette deck, generates a servo motor control signal to enable operation of the other deck in response to the key input. Here, the following five occasions are assumed as regards the respective output state of the servo control signal: (1) when one deck is in STOP mode, the other deck is operated into RECORD mode; (2) when one deck is in PLAY mode, the other deck is operated into RECORD mode; (3) when one deck is in RECORD & PAUSE mode, the other deck is operated into PLAY mode; (4) when one deck is just in REWIND PICTURE SEARCH (RPS) or RECORD & PAUSE mode, the other deck is driven; and (5) after one deck is in RECORD & PAUSE mode and the other deck is in PLAY or STILL mode, both decks are operated in playback and record modes. To describe the above occasion (1) with reference to Figure 3, when a first deck is in STOP mode, the mode switches A and C is at logic low and the mode switch B is at logic high, when a copy key input is received to the microprocessor and thereafter a video record signal of a second deck is outputted. Hence, it is possible to place the second deck in RECORD mode while placing the first deck in STOP mode. In the second occasion (2) mentioned above, when the first deck is in PLAY mode, the mode switches A and C, as shown in Figure 4, is at logic high state and the mode switch B is at logic low state, by checking which mode signals the video record signal of the second deck is outputted. Further, in the occasions (3) and (4), as shown in Figure 5, when inputs of the mode switches A, B and C of the first deck are received as desired, a record drive signal of the second deck is provided. Furthermore, in the occasion (5), as shown in Figure 6, when the inputs of the mode switch A, B and C in the first deck are applied into a RECORD PAUSE mode and the inputs of the mode switches A, B and C in the second deck are applied into PLAY or STILL mode, then the first deck provides a playback signal and the second deck provides a record signal, thereby enabling a copying operation in the double-deck VCR. As is understood in the foregoing description, the copy timing control circuit according to the present invention may be used to prevent the waste of video tape and further to enable the correct tape positioning upon tape-to-tape copying mode. Further, this and other advantages of the invention can be achieved by checking mode switch inputs in one cassette deck and, when a desired mode switch input is received, enabling drive of the other cassette deck to record the video signal from the one cassette deck. That is, synchronism between both decks are effectively obtained.

Claims: A copy timing control circuit for use in a double-deck video cassette recorder having at least a first video cassette deck and a second video cassette deck capable of tape-to-tape copying of video data therebetween, said circuit comprising: a mode signal input means for receiving first mode selection signals from said first video cassette deck and second mode selection signals from said second video cassette deck produced by application of mode switches in said respective video cassette decks; a copy signal input means for receiving a copy signal produced by application of a copy key, a control means (15) operably connected to said mode signal input means and a said copy signal input means, for producing a servo control signal dependent upon receipt of a given state of said mode selection signals and said copy signal; and motor driving means (5 or 10), connected to receive said servo control signal, for controlling the drive of said other video cassette deck in response to said servo control signal; characterised in that said control means (15) produces said servo control signal when said first mode selection signals are indicative of a record pause mode of said first video cassette deck and said second mode selection signals are indicative of a playback mode or a still mode of said second video cassette deck, and said control means is for producing said servo control signal to enable a record mode of said second video cassette deck in response to receipt of said copy signal when said first mode selection signals are indicative of a stop mode of said first video cassette deck. A method for controlling a double-deck video cassette recorder having at least a first video cassette deck and a second video cassette deck capable of tape-to-tape copying of video data therebetween, said method comprising the steps of : receiving mode signal inputs of first mode selection signals from said first video cassette deck and second mode selection signals from said second video cassette deck produced by application of mode switches in said respective video cassette decks; receiving copy signal input of a copy signal produced by application of a copy key, producing a servo control signal from a control means (15) operably connected to said mode signal input means and a said copy signal input means, said servo control signal being dependent upon receipt of a given state of said mode selection signals and said copy signal; and controlling the drive of said other video cassette deck by motor driving means (5 or 10), connected to receive said servo control signal, in response to said servo control signal; characterised in that said control means produces said servo control signal when said first mode selection signals are indicative of a record pause mode of said first video cassette deck and said second mode selection signals are indicative of a playback mode or a still mode of said second video cassette deck, and said method includes steps of producing said servo control signal to enable a record mode of said second video cassette deck in response to receipt of said copy signal when said first mode selection signals are indicative of a stop mode of said first video cassette deck.

Inventors: CHO NAM-YOUNG, CHO, NAM-YOUNG
Applicants: SAMSUNG ELECTRONICS CO LTD, SAMSUNG ELECTRONICS CO., LTD.
Application year: 1991
Main classification: G11B27
IPC codes: G11B27, G11B15