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US 4,376,292 AGranted
Apparatus for erasing and reproducing audio signals
AssigneeU.S. Philips Corporation
InventorGeorges M. A. Mignolet
Life of this patent
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Abstract
A passage of a previously recorded audio signal is erased from a magnetic tape such that a substantially linear decrease or increase of the sound level is perceived by the operator when the signal is reproduced by a reproducing head. The erase current is increased as a function of time from a minimum to a maximum amplitude, sequentially, through three ranges, and decreased in reverse order. The slopes of current versus time within the first and third ranges have a value substantially greater than the slope within the second range.
Claims13
An apparatus for reproducing audio signals recorded on a magnetic recording medium, which comprises:
- a head for reproducing the audio signals;
- a head for erasing the audio signals;
- means associated with said erasing head for providing relative motion of the medium past said erasing head, and
- erase current generator means electrically connected to said erasing head for applying an erase current to said erasing head, said generator means including means for switching said generator means on and off such that, after switching on, said generator means applies to said erasing head a current whose amplitude increases as a first function of time and, after switching off, applies to said erasing head a current whose amplitude decreases as a second function of time, at least one of said functions of time having first, second and third sequential ranges, in each of said ranges the current having a respective slope as a function of time, which slope is determined primarily by respective first, second and third time constants, said first and third time constants each being substantially greater than the second time constant.
1 more element
A device for erasing a passage of audio signals recorded on a magnetic recording medium, which comprises:
- a head for erasing the audio signals;
- means associated with said erasing head for providing relative motion of the medium past said erasing head, and
- erase current generator means electrically connected to said erasing head for applying an erase current to said erasing head, said generator means including means for switching said generator means on and off such that, after switching on, said generator means applies to said erasing head a current whose amplitude increases as a function of time and, after switching off, applies to said erasing head a current whose amplitude decreases as a function of time,
- characterized in that said generator means includes means for producing an erase current whose amplitude, after switching on,
- (1) increases from a minimum to a maximum amplitude sequentially through a first range, a second range and a third range and,
- (2) after switching off, decreases through said ranges in reverse order from the maximum to the minimum amplitude,
- (3) has a slope as a function of time, which slope, in said first range, is determined primarily by a first constant;
- in said second range, is determined primarily by a second constant;
- in said third range, is determined primarily by a third constant;
- (4) the first and third constants each have a value substantially greater than the second constant.
7 more elements
An apparatus for reproducing audio signals recorded on a magnetic recording medium, which comprises:
- a head for reproducing the audio signals;
- a head for erasing the audio signals
- means associated with said erasing head for providing relative motion of the medium past said erasing head, and
- erase current generator means electrically connected to said erasing head for applying an erase current to said erasing head, said generator means including means for switching said generator means on and off such that, after switching on, said generator means applies to said erasing head a current whose amplitude increases as a function of time and, after switching off, applies to said erasing head a current whose amplitude decreases as a function of time,
- characterized in that said generator means includes means for producing an erase current whose amplitude, after switching on,
- (1) increases from a minimum to a maximum amplitude sequentially through a first range, a second range and a third range and,
- (2) after switching off, decreases through said ranges in reverse order from the maximum to the minimum amplitude,
- (3) has a slope as a function of time, which slope, in said first range, is determined primarily by a first constant;
- in said second range, is determined primarily by a second constant;
- in said third range, is determined primarily by a third constant;
- (4) the first and third constants each have a value substantially greater than the second constant, at least the boundary between the first and the second ranges as well as the ratio of the values of the first and the second constants being selected such that, upon reproduction of an audio signal erased by said generator means, the amplitude of the reproduced signal varies substantially in accordance with a single logarithmic function of time.
8 more elements
Dependencies are inferred from the claim text.