Dynamic information storage or retrieval – Editing of stored information
Patent
1989-09-11
1992-02-25
Levy, Stuart S.
Dynamic information storage or retrieval
Editing of stored information
360 143, 360 361, G11B 2700, G11B 2702, H04N 578
Patent
active
050918990
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a time code recording and reproducing apparatus recording and reproducing signals of sounds, images, and others, and time codes corresponding thereto in an R-DAT (a rotary head type digital audio tape recorder), a digital VTR, and others.
BACKGROUND ART
Recently, digital techniques have been used in many fields such as an audio or a video field, and techniques of a CD player, and R-DAT, a digital VTR, and others have been established.
Among them, a time code control technique has been important together with a basic technique of recording and reproducing a PCM signal, the time code control technique recording time codes in correspondence with the PCM signal and performing sync recording, sync reproducing, and sync editing by connecting a plurality of recording and reproducing apparatuses searching a head of a point of the recording or the reproducing.
In a prior art time code recording and reproducing apparatus, PCM samples are divided into frames, a time code having a minimal unit of a frame number is recorded for each frame, and one time code is given to a plurality of PCM samples belonging to one frame.
Ways of recording time codes which are defined as mentioned above are classified into two types, that is, (1) a rotary head type and (2) a fixed head type.
(1) The rotary head type
The R-DAT records time codes by a rotary head. In the R-DAT, since the frame frequency is generally 2000/60 Hz, time codes of 2000/60 frames are recorded during one second. In this case, since the time codes are recorded and reproduced by the rotary head and thus variations in relative speeds of the head and the tape are small when the tape speed varies, the range of the tape speeds which can be reproduced is large.
In the R-DAT, the reproduction of the time codes is possible between a stationary state and a 200-times speed.
(2) The fixed head type
In general, a rotary head type VTR uses a fixed head in recording time codes. Also in this case, the recording is generally performed in synchronism with a track period recorded by the rotary head. However, in the case where the time codes are recorded by the fixed head, since the recording is possible even when it is out of synchronization with the track recorded by the rotary head, the recording is possible even when time codes having different frame periods are inputted. The collection of preliminary papers of AES Tokyo Convention '87, pages 93 to 94, discloses a way of recording SMPTE time codes into an R-DAT optional track by a fixed head, the time codes having a frame frequency of about 29.97 Hz for a VTR.
(1) Problem in the fixed head type
The time code recording of the fixed head type suits to the transfer of time codes between apparatuses of different types since it can perform the recording independent of the recording frame of the rotary head even when the frame period and the phase of the input time codes disagree with the frame period and the phase of the recording apparatus. However, in the time code recording by the fixed head, since the relative speeds of the head and the tape are determined by the tape speed, there is a problem that the range of the tape speeds which can be reproduced is narrow. In addition, in the case of a recording and reproducing apparatus such as an R-DAT which has a low standard tape speed (8.15 mm/SEC), the reproduction of the time codes at the standard tape speed is difficult. In addition, in the fixed head type, since the accuracy of the attachment location of the fixed head directly affects the accuracy of the recording phase of the time codes, it is difficult to maintain the accuracy. Furthermore, the fixed head type needs the fixed head in addition to the rotary head, and it has a problem that miniaturizing the mechanism is difficult.
Therefore, it is understood that the time code recording by the rotary head type suits to an apparatus such as an R-DAT or a rotary head type VTR which records a main signal by a rotary head.
(2) Problem in the rotary head type
The time code recording of the rot
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Patents Abstracts of Japan, vol. 14, No. 25 (P-991) (3968) 16 Jan. 1990, JP-A-01 264686 (Matsushita Electric IND CO LTD) 20 Oct. 1989.
Adachi Tatsuya
Ejima Naoki
Nagai Kiyotaka
Nakajima Yasushi
Nikaido Masataka
Levy Stuart S.
Matsushita Electric - Industrial Co., Ltd.
Nguyen Tan
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