Dynamic magnetic information storage or retrieval – Monitoring or testing the progress of recording
Reexamination Certificate
1998-09-28
2001-12-04
Hindi, Nabil (Department: 2651)
Dynamic magnetic information storage or retrieval
Monitoring or testing the progress of recording
C360S128000
Reexamination Certificate
active
06327104
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic recording and reproducing apparatus having a function of detecting clogging of a magnetic head occurring when recording or reproducing video or audio signals on a magnetic recording tape through the magnetic head.
Clogging of a magnetic head is a phenomenon that dust or magnetic powder accumulates on the area contacting with a magnetic recording tape around a gap of the magnetic head. Clogging of magnetic head impedes normal contact of the magnetic head and the magnetic recording tape, or changes magnetic characteristics of the magnetic head. As a result, normal magnetic recording is disabled.
A technology of detection of clogging of magnetic head is disclosed, for example, in Japanese Laid-open Patent No. 59-104707 (laid open on Jun. 16, 1984). Herein, a reproducing magnetic head is disposed at a position on a rotary cylinder, different from that of a recording magnetic head, and clogging of the magnetic head in recording operation is detected by continuously monitoring the output of the reproducing magnetic head.
Including this example, in the method of detecting clogging of magnetic head, the amplitude value of reproduced signal at the time of deterioration of video recording quality and the envelope of reproduced signal are compared. In this method, when the envelope of reproduced signal is small, it is judged that recording abnormality due to clogging of magnetic head occurs, and a detection signal (alarm signal) is issued.
In this method, however, to detect clogging of magnetic head when recording, the magnetic head clogging detecting device is being operated continuously. It increases the power consumption of the magnetic recording and reproducing apparatus. In particular, in the case of a video tape recorder with a built-in camera which is often driven by a battery, this problem is troublesome. The increase in power consumption of the video tape recorder with a built-in camera has a substantial effect on the battery life.
A more specific example is given below.
Battery-driven portable video tape recorders with a built-in camera are widely used recently for broadcasting and professional use, in news gathering activities, and the like. In such applications, detection of clogging is necessary for recording securely. At the same time, in order to record for a longer time, it is also necessary to suppress the increase of power consumption due to detection of clogging.
Moreover, in the portable video tape recorder with a built-in camera, in order to reduce its size, the body of apparatus is required to be smaller. Downsizing of the body of apparatus is a troublesome condition for temperature rise due to power consumption in the electric circuit. Therefore, also for the purpose of reducing the size of the body of apparatus, it is demanded to suppress increase of power consumption due to detection of clogging.
SUMMARY OF THE INVENTION
It is hence an object of the invention to provide a magnetic recording and reproducing apparatus capable of reducing power consumption when recording.
In the invention, detection of clogging of magnetic heads in recording is done intermittently only for predetermined periods, and while clogging of magnetic head is not detected, the operation of the detecting unit of clogging of magnetic head is stopped. The invention also discloses to turn off the power source of the detecting unit in the periods not detecting clogging of magnetic heads. As a result, power consumption can be saved. Therefore, the battery-operated video tape recorders can be used for a longer time. The invention further allows the user to set freely the periods for detecting clogging of magnetic heads, or the detecting sensitivity of clogging of magnetic head.
The invention also relates to a magnetic recording and reproducing apparatus having a plurality of sets, each set including a recording magnetic head and a reproducing magnetic head disposed at a position different from that the recording magnetic head disposed at, on a rotary cylinder, for drawing plural track patterns on a magnetic recording tape. In the magnetic recording and reproducing apparatus above, by switching the outputs of the reproducing magnetic heads, the detecting unit of clogging of magnetic head in the constitution described above is shared. As a result, the rise of power consumption due to the increase of number of magnetic heads does not occur owing to sharing of the detecting unit of clogging of magnetic head. Therefore, in addition to the effect of reducing the power consumption in the detecting unit of clogging of magnetic head in the constitution described above, the power consumption can be further kept low.
Examples of magnetic recording system for drawing plural track patterns on magnetic recording tape mentioned above include a system of recording television signals by separating into luminance signals and chrominance signals.
REFERENCES:
patent: 4827361 (1989-05-01), Yoshioka
patent: 5193033 (1993-03-01), Shimoi et al.
patent: 5694263 (1997-12-01), Miyahara et al.
patent: 59-104707 (1984-06-01), None
Kase Tsutomu
Kataoka Kazuhiro
Hindi Nabil
Matsushita Electric - Industrial Co., Ltd.
Neal Regina Y
Ratner & Prestia
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