JPH0574136B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a tape speed control method, particularly
The present invention relates to a tape speed control method suitable for application to tape speed control at the start of a high-speed search in a DAT device (digital audio tape recording and reproducing device).

<Prior Art> In a DAT device, a head is rotated diagonally with respect to the longitudinal direction of a magnetic tape, audio data is digitally recorded on the magnetic tape by the head, and the audio data is read and reproduced from the magnetic tape. Two recording/playback heads are arranged on a rotating body (cylinder) at an interval of 180 degrees from each other, and the magnetic head is moved so that the trajectory of each head on the magnetic tape surface is inclined with respect to the longitudinal direction of the magnetic tape. The relative positional relationship between the tape and each head is determined. Each time the cylinder rotates 180 degrees, each head alternately contacts the magnetic tape to record audio data on the magnetic tape or read audio data from the magnetic tape. The read signal (playback signal) is input to the PLL circuit,
Here, the clock signal included in the reproduced signal is reproduced, and the demodulator reads the reproduced signal in synchronization with the reproduced clock signal and stores it in the built-in RAM.
Thereafter, the audio data stored in the RAM is subjected to error detection and correction processing, DA converted, and output.

Such a DAT device uses subcode information recorded together with audio data to have search functions based on track number, index, and absolute time. For example, when searching by song number, by reading and counting the subcode information, a desired song can be searched and the beginning of the song can be searched, or intro scans and other plays can be performed at high speed.
This search is performed at 200 times the tape feed speed during normal playback, and the cylinder rotation speed is 3023 revolutions/min during fast forwarding and 960 revolutions/min during unwinding.

<Problems to be Solved by the Invention> Considering the rise in tape feed speed during a search, it would be ideal for the tape feed speed to instantly rise to the target speed, but in reality, the tape speed does not reach the target speed (e.g.
It takes a certain amount of time to stabilize at 200x speed). During this rising period, the relative speed between the head and tape is not constant. Therefore, a certain amount of time is required from the start of the search until the subcode can actually be read. In other words,
The subcode cannot be read for a certain period of time from the start of the search, which may result in malfunctions during searches, etc.

For example, with a DAT device, at the beginning of a song, there are 9 seconds,
A start ID indicating the beginning of a song is recorded, and when searching by song number, the start ID is used to locate the beginning, perform an intro scan, and perform other plays. For this reason, in the conventional method, when searching for a track number from the current tape running position, depending on the current tape running position, the start ID may not be readable due to the rise time. Malfunctions occur during play.

In light of the above, an object of the present invention is to provide a tape speed control method that allows subcode information to be read even when a high-speed search is started.

<Means for solving the problems> FIG. 1 is a block diagram of an embodiment of the present invention. 1
1 is a signal processing section, 11a is a PLL circuit, 11b is a demodulation section, 11c is a lock detection circuit, 11d is a subcoat processing section, 12 is a tape speed control section, 12a
12 is a tape speed data storage memory, 12b is a microcomputer, 12c is a reel speed servo circuit, 13 is a reel motor, 14 is a recording/reproducing head, and 15 is a magnetic tape.

<Function> The PLL stores the speed data at each step when the search speed is gradually increased in a stepwise manner in the memory 12a, and reproduces the clock signal included in the reproduction signal read from the magnetic tape 15.
The lock detection circuit 1 detects that the circuit 11a is locked.
Detected by 1c, microcontroller 12b uses PLL during search
Each time the circuit locks, speed data one step higher is read from the memory 12a, and the speed data is applied to the reel speed servo circuit 12c to drive the reel motor 13 and control the tape speed in a stepwise manner.

According to this method, the PLL circuit is intermittently locked even when the search is started (while the tape speed is increasing), so the subcode information can be read even before the tape speed reaches the search speed, and the search There is no malfunction when

<Embodiment> FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 is an explanatory diagram of the control method of the present invention.

In FIG. 1, 11 is a signal processing section, 12 is a tape speed control section, 14 is a recording/playback head, 15 is a magnetic tape, and 16 is a playback amplifier.

The signal processing unit 11 includes a PLL circuit 11a that reproduces the clock signal CL included in the reproduced signal AS read from the magnetic tape 15, and a PLL circuit 11a that reproduces the clock signal CL included in the reproduced signal AS read from the magnetic tape 15.
It reads the playback signal AS in synchronization with
The demodulator 11b stores the data in the RAM and then performs error detection/correction processing on the data stored in the RAM and outputs the data, and the PLL circuit 11a detects that the data is locked and outputs the lock detection signal PLD. The lock detection circuit 11c and the demodulation section 11b
A subcode processing unit 11d that identifies subcodes included in data output from and performs predetermined processing.
have.

The tape speed control unit 12 controls the search speed V _s (second
(See figure) A tape speed data storage memory 12a stores the speeds V ₁ , V ₂ , V ₃ , etc. at each step when the speeds are gradually increased in a stepwise manner up to
Every time the PLL circuit 11a locks, the current speed data is
Store speed data V _i+1 one step higher than V _i in memory 1.
a microcomputer 12b that reads from 2a and outputs it;
It has a reel speed servo circuit 12c that controls the rotational speed of the reel 13 based on speed data output from a microcomputer.

When a predetermined key on the operation panel (not shown) is pressed and a desired song number and search command SCC are generated, the microcomputer 12b compares the size of the current song number and the desired song number to identify whether to fast forward or rewind. , the speed data V ₁ (see FIG. 2) of the first step is read from the tape speed data storage memory 12a, and the speed data V ₁ and the rotation direction are applied to the reel speed servo circuit 12c. As a result, the reel speed servo circuit 12c rotates the reel motor 13 in a predetermined direction at a predetermined speed using well-known servo control to feed the tape at _V1 . In addition, in parallel with the tape speed control described above, the rotational speed of the cylinder is also controlled, and the recording/playback head 1 attached to the cylinder is also controlled.
A reproduced signal AS read from the magnetic tape 15 by 4 is applied to the PLL circuit 11a and the demodulator 11b.

In such a state, the lock detection circuit 11c
If the PLL circuit 11a locks, the lock detection circuit
Generates PLD (see Figure 2).

When the lock detection signal PLD is generated, the microcomputer 12b reads the speed data _V2 of one step higher from the memory 12a, applies the speed data _V2 to the reel speed servo circuit 12c, and similarly drives the reel motor to tape the tape. The speed is set to _V2 , and thereafter, the microcomputer 12b reads the speed data one step higher from the memory 12a every time the PLL circuit locks, and controls the tape speed stepwise up to the search speed _Vs.

After reaching the search speed, the search speed V _s
Rotation control of the reel motor 13 is performed so that the reel motor 13 travels at a speed of 1.

On the other hand, the start ID is subcode processing unit 11d
Each time the subcode processing unit 11d generates a start ID detection signal SID, the microcomputer 12b updates the current track number according to the rotation direction.
When the current song number and the target song number become equal, the search control ends, and the tape is then fed at the playback speed to play back the music.

<Effects of the Invention> According to the present invention, the PLL circuit is intermittently locked even at the start of a search (when the tape speed is increasing) to read subcode data recorded on the magnetic tape. This makes it possible to reliably identify the start ID during high-speed searches and eliminate search malfunctions.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the method of the present invention, and FIG. 2 is an explanatory diagram of the control method of the present invention. 11...signal processing unit, 11a...PLL circuit,
11b... demodulation section, 11c... lock detection circuit,
11d...Subcode processing unit, 12...Tape speed control unit, 12a...Tape speed data storage memory, 12b...Microcomputer, 12c...Reel speed servo circuit, 13...Reel motor, 15...Magnetic tape.

Claims (1)

[Claims] 1. Tape speed control at the time of search of a digital audio tape device that feeds a magnetic tape in the tape longitudinal direction and rotates the head to record signals on the magnetic tape or read and reproduce signals from the magnetic tape. In this method, the speed data at each step when the search speed is gradually increased in a stepwise manner is stored in memory, and the PLL circuit that plays back the clock signal included in the playback signal read from the tape during the search is locked. 1. A tape speed control method, comprising: detecting that the PLL circuit is locked, reading speed data one step higher from the storage means every time the PLL circuit locks, and controlling the tape feeding speed based on the speed data.