US3705272A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Noise diminishing switching circuit for magnetic recording-reproducing device
Assignee: Canon Inc
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Filing: 1970-07-15
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Granted: 1972-12-05
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Expires: 1990-07-15
Abstract
Abstract A magnetic recording-reproducing device comprises at least one switchable recording-reproducing head and at least one erase head. In a high-frequency bias recording system, high-frequency bias is applied to the recording-reproducing head in addition to the signals to be recorded on the magnetic recording medium. Also in a high-frequency erasing system, high-frequency erasing current is applied to the erase head. In both cases, in switching the operation modes of each head from one to the other and vice versa, the annoying noise is recorded on the recording medium because of the high-frequency current applied to the respective heads. In order to eliminate the noise, prior to mode switching of the heads, the high-frequency current is interrupted and thereafter high-frequency current is supplied to the heads.
Inventors
- 👤 Takao Tsuji
- 👤 Minoru Yoshikawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 14:26
CPC Classifications
G; G11; G11B; G11B23/00; G11B23/0007; G11B5/00
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
307 words
A magnetic recording-reproducing device having a magnetic recording medium upon which is recorded the information, an erase head and a recording and reproducing head, comprising; a high frequency signal generating circuit electrically coupled to said head for generating high frequency signals for bias and erasing current, the frequency of which signals is higher than a frequency range of the information signals; a switching circuit electrically coupled between said high frequency generating circuit and the erase and recordingreproducing heads for interrupting the output of said high frequency signal generating circuit; an information signal source electrically coupled to said head for producing an electrical signal to be recorded on said medium; recording and reproducing mode selection switches having a first switch and a second switch which are turned over simultaneously, the first switch being electrically connected between said erase head and said switching circuit, and the second switch being electrically connected between said recording head and said information signal source, said erase head and said recording and reproducing head being juxtaposed each other in the direction of transfer of the recording medium; time delay circuit means operatively connnected to said switching circuit and having a trigger to turn-off and to delay to turn-on the switch circuit, said time delay circuit means having a trigger actuating member associated operatively with said mode selection switches in a timed relation so as to trigger said delay circuit before the turn-over of said mode selection switches, the delay time being so selected that said delay circuit interrupts said switching circuit prior to the switching of said first and second switches whereby when said first and second switches are being switched, no high frequency signals at high level are applied to said erase and recordingreproducing heads, thereby preventing the noise due to said high frequency signals from being recorded on said magnetic recording medium.
Claim 2
Dependent Claim
307 words
A magnetic recording-reproducing device having a magnetic recording medium upon which is recorded the information, an erase head and a recording and reproducing head, comprising; a high frequency signal generating circuit electrically coupled to said head for generating high frequency signals for bias and erasing current, the frequency of which signals is higher than a frequency range of the information signals; a switching circuit electrically coupled between said high frequency generating circuit and the erase and recordingreproducing heads for interrupting the output of said high frequency signal generating circuit; an information signal source electrically coupled to said head for producing an electrical signal to be recorded on said medium; recording and reproducing mode selection switches having a first switch and a second switch which are turned over simultaneously, the first switch being electrically connected between said erase head and said switching circuit, and the second switch being electrically connected between said recording head and said information signal source, said erase head and said recording and reproducing head being juxtaposed each other in the direction of transfer of the recording medium; time delay circuit means operatively connnected to said switching circuit and having a trigger to turn-off and to delay to turn-on the switch circuit, said time delay circuit means having a trigger actuating member associated operatively with said mode selection switches in a timed relation so as to trigger said delay circuit before the turn-over of said mode selection switches, the delay time being so selected that said delay circuit interrupts said switching circuit prior to the switching of said first and second switches whereby when said first and second switches are being switched, no high frequency signals at high level are applied to said erase and recordingreproducing heads, thereby preventing the noise due to said high frequency signals from being recorded on said magnetic recording medium.
Claim 3
Dependent Claim
32 words
A magnetic recording-reproducing device as defined in claim 1 wherein said time delay circuit has a second switching means which are actuated prior to the actuation of said first and second switches.
Claim 4
Dependent Claim
76 words
A magnetic recording-reproducing device as defined in claim 2 wherein said switching means comprises an electronic switch employing semiconductive elements; said delay circuit comprises a monostable multivibrator which is triggered by said second switching means which in turn is actuated prior to the switching of said mode seleCtion switches, the time constant which determines a reset time of said monostable multivibrator being slightly longer than a time interval required for switching of said mode selection switches.
Claim 5
Dependent Claim
84 words
A magnetic recording-reproducing device as defined in claim 2 wherein said second switching means is a mechanical switch whose contacts are closed and opened by a switch actuating member which in turn is actuated in unison with an operating member; said mode selection switches have a switch actuating member, said second switch actuating member engages with said mode selection switch actuating member so as to be driven after said second switching means is activated by said operating member, thereby switching said mode selection switches.
Claim 6
Dependent Claim
249 words
A switching noise diminishing device for a magnetic recording and reproducing apparatus including at least one magnetic conversion head for recording signals upon magnetic recording medium and reproducing said signals, comprising; means electrically coupled to said head for generating high frequency bias signals whose frequency is higher than the frequency range of the signals to be recorded upon said magnetic recording medium; switching means electrically coupled between said generating means and the magnetic conversion head for interrupting the output of said high frequency bias signal to the head, said switching means having a turn-over actuating member; an information signal source electrically coupled to said head for producing an electrical signal to be recorded on said medium; recording and reproducing mode selection switches different from said switching means and having a first switch and a second switch which are turned over simultaneously, the first switch being electrically connected between said head and said switching means, and the second switch being electrically connected between said head and said information signal source, the mode selection switches being arranged to disconnect the bias signal from said head when its reproducing mode is selected; said mode selection switches being operative-engageably connected with said actuating member of said switching means for turn-over in sequentially delayed timed relation; whereby the high level, high frequency bias signals applied to said magnetic conversion head are interrupted while said selection switches are being switched, thereby preventing the noise due to turn-over of said mode selection switches from being recorded.
Claim 7
Dependent Claim
249 words
A switching noise diminishing device for a magnetic recording and reproducing apparatus including at least one magnetic conversion head for recording signals upon magnetic recording medium and reproducing said signals, comprising; means electrically coupled to said head for generating high frequency bias signals whose frequency is higher than the frequency range of the signals to be recorded upon said magnetic recording medium; switching means electrically coupled between said generating means and the magnetic conversion head for interrupting the output of said high frequency bias signal to the head, said switching means having a turn-over actuating member; an information signal source electrically coupled to said head for producing an electrical signal to be recorded on said medium; recording and reproducing mode selection switches different from said switching means and having a first switch and a second switch which are turned over simultaneously, the first switch being electrically connected between said head and said switching means, and the second switch being electrically connected between said head and said information signal source, the mode selection switches being arranged to disconnect the bias signal from said head when its reproducing mode is selected; said mode selection switches being operative-engageably connected with said actuating member of said switching means for turn-over in sequentially delayed timed relation; whereby the high level, high frequency bias signals applied to said magnetic conversion head are interrupted while said selection switches are being switched, thereby preventing the noise due to turn-over of said mode selection switches from being recorded.
Claim 8
Dependent Claim
274 words
A switching noise diminishing device for a magnetic recording and reproducing apparatus including at least one magnetic conversion head for recording signals upon magnetic recording medium and reproducing said signals, comprising; means electrically coupled to said head for generating high frequency bias signal whose frequency is higher than the frequency range of signals to be recorded upon said magnetic recording medium; switching means electrically coupled between said generating means and the magnetic conversion head for interrupting the output of said high frequency bias signal to the head; an information signal source electrically coupled to said head for producing an electrical signal to be recorded on said medium; recording and reproducing mode selection switches different from said switching means and having a first switch and a second switch which are turned over simultaneously, the first switch being electrically connected between said head and said switching means, and the second switch being electrically connected between said head and said information signal source, the mode selection switches being arranged to disconnect the bias signal from said head when its reproducing mode is selected; delay means associated with said switching means to turn-off and delay its turn-on, said delay means have a trigger switching means for starting the delay operation and having a predetermined time delay in which said mode selection switches are turned-over, the trigger switching means being Operatively connected with said mode selection switches in sequentially delay timed relation, whereby the high level frequency bias signals applied to said magnetic conversion head are interrupted while said selection switches are being switched, thereby preventing the noise due to turn-over of said mode selection switches from being recorded.
Claim 9
Dependent Claim
274 words
A switching noise diminishing device for a magnetic recording and reproducing apparatus including at least one magnetic conversion head for recording signals upon magnetic recording medium and reproducing said signals, comprising; means electrically coupled to said head for generating high frequency bias signal whose frequency is higher than the frequency range of signals to be recorded upon said magnetic recording medium; switching means electrically coupled between said generating means and the magnetic conversion head for interrupting the output of said high frequency bias signal to the head; an information signal source electrically coupled to said head for producing an electrical signal to be recorded on said medium; recording and reproducing mode selection switches different from said switching means and having a first switch and a second switch which are turned over simultaneously, the first switch being electrically connected between said head and said switching means, and the second switch being electrically connected between said head and said information signal source, the mode selection switches being arranged to disconnect the bias signal from said head when its reproducing mode is selected; delay means associated with said switching means to turn-off and delay its turn-on, said delay means have a trigger switching means for starting the delay operation and having a predetermined time delay in which said mode selection switches are turned-over, the trigger switching means being Operatively connected with said mode selection switches in sequentially delay timed relation, whereby the high level frequency bias signals applied to said magnetic conversion head are interrupted while said selection switches are being switched, thereby preventing the noise due to turn-over of said mode selection switches from being recorded.
Claim 10
Dependent Claim
58 words
A switching noise diminishing device as defined in claim 6, wherein said switching means has a switch actuating member for activating the trigger switching means and mode selection switches in a timed relation and, said switching means and trigger switching means are simultaneously actuated prior to the switching of said mode selection switches by operating said actuating member.
Claim 11
Dependent Claim
78 words
A switching noise diminishing device as defined in claim 6 wherein said switching means comprises an electronic switch employing semiconductive elements; said delay means comprises a monostable multivibrator which is triggered by said trigger switching means which in turn is actuated prior to the switching of said mode selection switches, the time constant which determines a reset time of said monostable multivibrator being slightly longer than a time interval required fro the switching of said mode selection switches.
Claim 12
Dependent Claim
85 words
A switching noise diminishing device as defined in claim 6 wherein said trigger switching means is a mechanical switch whose contacts are closed and opened by functions; switch actuating member which in turn is actuated in unison with an operating member, said mode selection switches have a switch actuating member, said trigger switch actuating member engages with said mode selection switch actuating member so as to be driven after said trigger switching means is activated by said operating member, thereby switching said mode selection switches.
Claim 13
Dependent Claim
60 words
A noise diminishing device as defined in claim 6 wherein said magnetic conversion head comprises a magnetic head having both of the erasing and recording fucntions; the high frequency signals are applied from said high frequency signal generating means to said magnetic head in case of recording and the signals to be recorded are superposed upon the high frequency signals.
References Cited (Backward Citations)
US2531141A
Cited
US2596621A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-12-05 | 1976-06-05 | 1976-12-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-12-05 | 1980-06-05 | 1980-12-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-12-05 | 1984-06-05 | 1984-12-05 | $7700.00 | Window Closed / Lapsed |