Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the record
Reexamination Certificate
1998-11-05
2002-07-23
Sniezek, Andrew L. (Department: 2650)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the record
C360S048000, C360S018000
Reexamination Certificate
active
06424482
ABSTRACT:
FIELD OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording or reproducing apparatus of the rotary head type which can magnetically record a digital signal, and more particularly to a digital VCR (Video Cassette Recorder) which can record and reproduce plural signals of different data rates and surely reproduce data even when data are searched at a high speed.
2. Description of the Related Art
Conventionally, as a method of recording and reproducing plural signals of different data rates in a VCR, known is a method which is described in a publication of IEEE Transactions on Consumer Electronics, Vol. 40, No. 3, P. 263-268. This publication shows a technique of conducting multirate recording in a digital VCR without changing a recording density.
In the method, two heads of different azimuth angles are mounted on a rotary drum so as to be opposed to each other at a central angle of 180°. These heads are called a first head and a second head, respectively. When the rotary drum rotates, the first and second heads alternately scan a tape. Hereinafter, the description is made only on the recording operation. The reproducing operation is conducted in the same manner.
In normal record and reproduction (1-speed record and reproduction) in which an image is recorded and reproduced at a normal speed, a magnetic tape (hereinafter, referred to as merely “tape”) is caused to run at a predetermined speed (1-speed). First, the first head scans the tape, and the second tape then scans the tape so that signals are sequentially recorded.
In the ⅓-speed record and reproduction mode (⅓-speed record and reproduction) in which the rate of data to be recorded is one third that of the normal record and reproduction, the tape speed is reduced to ⅓. First, the first head scans the tape and records a signal. Next, the second head scans the tape and the first head then conducts the second scan. In the scan of the second head and the second scan of the first head, a signal is not recorded. When the second head then scans the tape, a signal is recorded. Similarly, when the first and second heads then scan the tape in sequence, a signal is not recorded. In the next scan of the first head, a signal is recorded. Then, the operation state returns to the initial state. The recording at the ⅓-data rate is conducted by repeating the above operation. In a similar manner, a signal can be recorded and reproduced at a 1
-data rate (where n is a positive odd number).
In addition to the configuration, a third head of an azimuth angle which is different from that of the first head may be colocated or placed at the same position so that, even when n is an even number, record and reproduction are enabled. Since the first and third heads are colocated, the scan operations conducted by the two heads are substantially coincident with each other.
When a signal of the data rate which is one half that of the normal record and reproduction is to be recorded and reproduced, for example, record and reproduction are conducted in the following manner. First, the tape speed is reduced to one half that of normal speed reproduction. When the first and third heads scan the tape, the first head conducts the signal recording but the third head does not conduct it. When the first and third heads scan the tape at the next time, the third head conducts signal record but the first head does not conduct it. Signal record at the ½-fold data rate is conducted by repeating the operation.
Even when n is a positive even number, signals can be generally recorded and reproduced at a 1
-fold data rate in a similar manner.
In such a prior art recording and reproducing apparatus, the first and third heads are to be colocated. Actually, however, it is difficult to dispose two heads at the same position, and hence the two heads are located at positions which are close to each other, respectively.
However, a prior art magnetic recording and reproducing apparatus is not provided with a measure against a problem which may be produced by the close arrangement of two heads. As a result, there arise problems in that the track width varies because the tape speed is changed in record modes of different data rates, and that the tracking margin which is tolerance for deviation of a head is reduced in search speed reproduction in which reproduction is conducted at a speed different from the normal one.
Conventionally, as a method of conducting search speed reproduction in a digital VCR, known is a method disclosed in Japanese Patent Publication (Kokai) No. HEI 2-94071.
In the disclosed method, when a video signal is to be recorded, a subcode area is formed on a tape. The subcode area is formed on the scanning locus of a head which is to be produced in search speed reproduction, and still image information extracted from the video signal is recorded in the subcode area in a distributed manner. In search speed reproduction, data recorded in the subcode area are reproduced so as to reproduce the still image information, thereby improving the image quality of variable speed reproduction.
In such a configuration, however, a speed at which still image information can be stably reproduced in search speed reproduction is restricted only to one kind. In a VCR at present, a speed of one kind is not sufficient for search speed reproduction. According to the prior art method, in order to cope with plural variable reproduction speeds, data must be recorded in a duplicate manner on all the scanning loci of heads which are to be produced in the plural variable reproduction speeds. This produces problems in that duplication of data is required so that reproduction of data is complicated, and that data are wasted.
In the prior art method, the record track must be made positionally coincident with the heads. Furthermore, the track in which the subcode area is formed must be selected in search speed reproduction, thereby producing a problem in that the mode shift from normal speed reproduction in which an image is reproduced at the normal speed to search speed reproduction requires a prolonged time period. In the prior art method, there is a further problem in that an AUX area in which additional information such as a program is to be recorded is disposed in the normal data area and hence information of the AUX area cannot be reproduced in search speed reproduction.
OBJECT AND SUMMARY OF THE INVENTION
It is an object of the present invention to suppress the variation in track width when plural signals of different data rates are recorded.
It is another object of the invention to reduce the failure in obtaining search information and surely reproduce search data in search speed reproduction.
The present invention is to easily realize search speed reproduction of a high image quality in a simple data arrangement.
The present invention is to reduce wasted search data and realize search speed reproduction of plural speeds.
The present invention is to provide a recording and reproducing apparatus which can surely reproduce search data even when the phase indicative of positional deviation between a head and a record track is not controlled in search speed reproduction.
The present invention is to provide a recording and reproducing apparatus in which it is not required to select a track to be scanned in search speed reproduction and the mode can be smoothly shifted from normal speed reproduction to search speed reproduction.
The present invention is to provide a recording and reproducing apparatus in which even a head of a width substantially equal to a track pitch can reproduce all effective search data.
The present invention is to provide a recording and reproducing apparatus which can reproduce information of an AUX area also in search speed reproduction.
In order to attain the objects, the recording and reproducing apparatus of the invention comprises: tape driving means for driving a tape; a rotary drum around which the tape is to be slantly wound; three heads, first, second, and third heads which are mounted on th
Gotoh Katsumi
Kobayashi Masa-aki
Kunihira Tadashi
Matsuura Kenji
Motosugi Masahiro
Akin Gump Strauss Hauer & Feld L.L.P.
Sniezek Andrew L.
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