US4564868A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Video tape recorder having improved audio characteristics
Assignee: Toshiba Corp
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Filing: 1983-02-02
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Granted: 1986-01-14
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Expires: 2003-02-02
Abstract
Abstract Audio signals to be recorded on a video cassette tape are frequency modulated by a frequency modulator. A subsequent pair of frequency converters produce audio signals whose carrier frequencies are different from each other. The audio signals are recorded on A and B tracks of a video cassette tape. In the playback mode, the audio signal reproduced by the video head is frequency reconverted using the same carrier frequencies that were used to frequency convert the signals. These frequency reconverted signals are then demodulated by an FM demodulator. The audio signals from the FM demodulator thus produce identical signals to the original audio signals which were recorded.
Inventors
- 👤 Yasunari Arafune
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 11:59
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/76; H04N5/91; H04N5/92; H04N9/00; H04N9/79; H04N9/80; H04N9/82; H04N9/83; H04N9/835; H04N9/8355
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
273 words
A video tape recorder comprising: first and second video heads adapted to helically scan a magnetic tape to record a sigal thereon or to reproduce a signal therefrom; frequency modulating means for frequency-modulating an audio source signal in a recording mode to produce a first audio recording signal; first frequency-converting means for frequency-converting the first audio recording signal in the recording mode to produce a second audio recording signal adapted to be recorded on said magnetic tape, and for frequency-converting a second audio playback signal reproduced from said magnetic tape in a playback mode to produce a first audio playback signal; second frequency converting means for frequency-converting the first audio recording signal in the recording mode to produce a third audio recording signal to be recorded on said magnetic tape and for frequency-converting a third audio playback signal reproduced from said magnetic tape in the playback mode to produce a first audio playback signal; FM demodulating means for FM-demodulating the first audio playback signals from said first and second frequency-converting means to reproduce an audio source signal; switching means for supplying the second and third audio recording signals from said first and second video heads, in the recording mode, and for supplying the second and third audio playback signals reproduced by said first and second video heads to said first and second frequency converting means, respectively, in the playback mode; and carrier generating means for generating first and second carrier signals for frequency conversion which are supplied to said first and second frequency converting means, respectively, the frequency of said first carrier signal being different from the frequency of said second carrier signal.
Claim 2
Dependent Claim
273 words
A video tape recorder comprising: first and second video heads adapted to helically scan a magnetic tape to record a sigal thereon or to reproduce a signal therefrom; frequency modulating means for frequency-modulating an audio source signal in a recording mode to produce a first audio recording signal; first frequency-converting means for frequency-converting the first audio recording signal in the recording mode to produce a second audio recording signal adapted to be recorded on said magnetic tape, and for frequency-converting a second audio playback signal reproduced from said magnetic tape in a playback mode to produce a first audio playback signal; second frequency converting means for frequency-converting the first audio recording signal in the recording mode to produce a third audio recording signal to be recorded on said magnetic tape and for frequency-converting a third audio playback signal reproduced from said magnetic tape in the playback mode to produce a first audio playback signal; FM demodulating means for FM-demodulating the first audio playback signals from said first and second frequency-converting means to reproduce an audio source signal; switching means for supplying the second and third audio recording signals from said first and second video heads, in the recording mode, and for supplying the second and third audio playback signals reproduced by said first and second video heads to said first and second frequency converting means, respectively, in the playback mode; and carrier generating means for generating first and second carrier signals for frequency conversion which are supplied to said first and second frequency converting means, respectively, the frequency of said first carrier signal being different from the frequency of said second carrier signal.
Claim 3
Dependent Claim
34 words
A video tape recorder according to claim 1, wherein said second and third audio recording signals are mixed with a video signal and are recorded together with said video signal on the magnetic tape.
Claim 4
Dependent Claim
51 words
A video tape recorder according to claim 2, wherein the video signal includes a luminance signal and a chrominance signal which have different frequency bands, and frequency bands of second and third recording and playback audio signals lie in a gap between the frequency bands of the luminance and chrominance signals.
Claim 5
Dependent Claim
53 words
A video tape recorder according to claim 1, wherein said carrier generating means comprises: said first carrier generating means for generating first carrier signals to be used in said first frequency converting means; and second carrier generating means for generating said second carrier signals to be used in said second frequency converting means.
Claim 6
Dependent Claim
114 words
A video tape recorder according to claim 1, wherein said first frequency converting means comprises a frequency converter and switch means for supplying the first audio recording signal from said frequency modulating means to the frequency converter in the recording mode and for supplying the second audio playback signal produced from said magnetic tape to the frequency converter in said playback mode, and said second frequency converting means comprises a frequency converter and switch means for supplying the first audio signal from said frequency modulating means to the frequency converter in the recording mode and for supplying the third audio signal produced from said magnetic tape to the frequency converter in the playback mode.
Claim 7
Dependent Claim
116 words
A video tape recorder according to claim 1, wherein said FM demodulating means comprises: a switch having a movable contact, a first stationary contact for receiving the first audio playback signal from said first frequency converting means in the playback mode and a second stationary contact for receiving the first audio playback signal from said second frequency converting means in the playback mode, said movable contact being selectively connected to said first and second stationary contacts substantially in synchronism with said helical scanning of said first and second video heads, thereby mixing audio signals from said first and second frequency converting means; and an FM demodulator for FM demodulating the selected audio signal from said switch.
Claim 8
Dependent Claim
68 words
A video tape recorder according to claim 1, wherein carrier generating means comprises: oscillating means for producing an oscillation signal which has a predetermined frequency; and carrier producing means for producing from the oscillation signal a first carrier signal for frequency conversion to be achieved by said first frequency converting means and a second carrier signal for frequency conversion to be achieved by said second frequency converting means.
Claim 9
Dependent Claim
87 words
A video tape recorder according to claim 7, wherein the oscillation signal has the same frequency as that of the first carrier signal; and said carrier producing means supplies the oscillation signal as the first carrier signal for frequency conversion to said first frequency converting means, frequency-divides the oscillation signal to produce a frequency-divided signal having a frequency equal to a difference between the frequencies of the first and second carrier signals, and frequency-converts the oscillation signal by the frequency-divided signal, thereby producing the second carrier signal.
Claim 10
Dependent Claim
34 words
A video tape recorder according to claim 8, wherein the oscillation signal has the frequency which is a natural number multiple of a difference between the frequencies of the first and second carrier signals.
Claim 11
Dependent Claim
207 words
A video tape recorder according to claim 1, wherein the audio signal to be frequency-modulated by said frequency modulating means is a stereophonic signal containing an L channel signal and an R channel signal, said frequency modulating means comprises a first frequency modulating section for frequency-modulating the L channel signal and a second frequency modulating section for frequency-modulating the R channel signal, said first frequency converting means comprises a first frequency converting section for frequency converting the L channel signal and a second frequency converting section for frequency-converting the R channel signal, said second frequency converting means comprises a first frequency converting section for frequency-converting the L channel signal and a second frequency coverting section for frequency-converting the R channel signal, said FM demodulating means comprises a first FM demodulating section for FM demodulating the L channel signal and a second FM demodulating section for FM demodulating the R channel signal, and said carrier generating means comprises means for generating first and second carrier signals of L channel and first and second carrier signals of the R channel, said first and second carrier signals of the L channel and said first and second carrier signals of R channel respectively having frequencies which are different from one another.
Claim 12
Dependent Claim
241 words
A video tape recorder according to claim 10, wherein the first frequency converting section of said first frequency converting means comprises a frequency converter and a switch for supplying the first audio signal of L channel to the frequency converter in the recording mode and for supplying the second audio signal of L channel reproduced from said magnetic tape to the frequency converter in the playback mode, the second frequency converting section of said first frequency converting means comprises a frequency converter and a switch for supplying the first audio signal of R channel to the frequency converter in the recording mode and for supplying the second audio signal of R channel reproduced from said magnetic tape to the frequency converter in the playback mode, the first frequency converting section of said second frequency converting means comprises a frequency converter and a switch for supplying the first audio signal of L channel to the frequency converter in the recording mode and for supplying the third audio signal of L channel reproduced from said magnetic tape to the frequency converter in the playback mode, and the second frequency converting section of said second converting means comprises a frequency converter and a switch for supplying the first audio signal of R channel to the frequency converter in the recording mode and for supplying the third audio signal of R channel reproduced from said magnetic tape to the frequency converter in the playback mode.
Claim 13
Dependent Claim
47 words
A video tape recorder according to claim 10, wherein said carrier generating means comprises a first carrier generating section for generating the first and second carrier signals of L channel and a second carrier generating section for generating the first and second carrier signals of R channel.
Claim 14
Dependent Claim
56 words
A video tape recorder according to claim 10, wherein said carrier generating means comprises oscillation means for generating an oscillation signal of a predetermined frequency and carrier producing means for producing the first and second carrier signals of said L channel and the first and second carrier signals of said R channel from said oscillation signal.
Claim 15
Dependent Claim
106 words
A video tape recorder according to claim 13, wherein any two adjacent ones of said carrier signals of said first and second carrier signals for said L channel and said first and second carrier signals for said R channel have the same frequency difference in the L and R channels, and said oscillation signal has a same frequency as one of said carrier signals, and wherein said carrier producing means produces a frequency-divided signal which has the same frequency as the frequency difference between the any two adjacent ones of said carrier and produces said carrier signals by frequency-converting said oscillation signal by said frequency-divided signal.
Claim 16
Dependent Claim
25 words
A video tape recorder according to claim 14, wherein said oscillation signal has a frequency which is a natural number multiple of said frequency difference.
Claim 17
Dependent Claim
39 words
A video tape recorder according to claim 14, wherein frequencies fa, fb, fc and fd of said carrier signals have a relation fa<fb<fc<fd, and said frequency of said oscillation signal is set to be one of fb and fc.
Claim 18
Dependent Claim
113 words
A video tape recorder according to claim 16, wherein the oscillation signal is frequency-converted by a frequency-divided signal corresponding to the oscillation signal which has one of the frequencies fb and fc, thereby producing carrier signals for frequency conversion which have one of a set of the frequencies fa and fc and a set of the frequencies fb and fd, and the carrier signal for frequency conversion which has one of the frequencies fc and fb is frequency-converted by the frequency-divided signal to produce the carrier signals for frequency conversion which have the other one of the set of the frequencies fb and fd and the set of the frequencies fa and fc.
Claim 19
Independent Claim
81 words
A method of recording high quality audio signals on a video tape, comprising the steps of: frequency modulating said audio signal to produce a single frequency modulated signal; first frequency converting said frequency modulated signal; independently of and simultaneously with said first frequency converting, second frequency converting said frequency modulated signal, said second frequency converting occurring at a different carrier frequency than said first frequency converting; selectively recording signals produced by said first and second frequency steps on said video tape.
Claim 20
Independent Claim
81 words
A method of recording high quality audio signals on a video tape, comprising the steps of: frequency modulating said audio signal to produce a single frequency modulated signal; first frequency converting said frequency modulated signal; independently of and simultaneously with said first frequency converting, second frequency converting said frequency modulated signal, said second frequency converting occurring at a different carrier frequency than said first frequency converting; selectively recording signals produced by said first and second frequency steps on said video tape.
Claim 21
Independent Claim
162 words
A method for recording high quality audio signals on a video tape and playing them back from the tape, comprising the steps of: frequency modulating said audio signal to produce a single frequency modulated signal; first frequency converting said frequency modulated signal; independently of and simultaneously with said first frequency converting, second frequency converting said frequency modulated signal, said second frequency converting occurring at a different carrier frequency than said first frequency converting; selectively recording signals produced by said first and second frequency converting steps on said video tape; sensing a signal on said video tape and producing signals indicative thereof; filtering said produced signal; first frequency re-converting said produced signal using a same carrier frequency as said first frequency converting; independently of and simultaneously with said first frequency re-converting, second frequency re-converting said produced signals using a same carrier frequency as in said second frequency converting; and selectively demodulating said frequency reconverted signals to thus obtain a playback audio signal therefrom.
Claim 22
Independent Claim
162 words
A method for recording high quality audio signals on a video tape and playing them back from the tape, comprising the steps of: frequency modulating said audio signal to produce a single frequency modulated signal; first frequency converting said frequency modulated signal; independently of and simultaneously with said first frequency converting, second frequency converting said frequency modulated signal, said second frequency converting occurring at a different carrier frequency than said first frequency converting; selectively recording signals produced by said first and second frequency converting steps on said video tape; sensing a signal on said video tape and producing signals indicative thereof; filtering said produced signal; first frequency re-converting said produced signal using a same carrier frequency as said first frequency converting; independently of and simultaneously with said first frequency re-converting, second frequency re-converting said produced signals using a same carrier frequency as in said second frequency converting; and selectively demodulating said frequency reconverted signals to thus obtain a playback audio signal therefrom.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-01-13 | 1989-07-15 | 1990-01-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-01-13 | 1993-07-15 | 1994-01-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-01-13 | 1997-07-15 | 1998-01-14 | $7700.00 | Window Closed / Lapsed |