JPH0584582B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a speed control method, and is particularly suitable for controlling the tape feed speed and head rotation speed at the start of a high-speed search in a digital audio tape device. This invention relates to a speed control method.

<Prior art> A head is rotated while being inclined relative to the longitudinal direction of the magnetic tape, and audio data is digitally recorded on the magnetic tape by the head,
and a digital audio tape device (R-DAT) that reads audio data from magnetic tape and plays it back.
There is a device (called a device).

The rotary head configuration used in such an R-DAT device has substantially the same configuration as the rotary head in a VTR. That is, as shown in Fig. 5, two recording/playback heads HD1 and HD2 are arranged on a rotary body (cylinder) RB at an interval of 180 degrees from each other, and the magnetic tape MT surface of each head HD1 and HD2 is placed on the rotating body (cylinder) RB. The relative positional relationship between the magnetic tape MT and each head is determined such that the running trajectory of the magnetic tape MT is inclined with respect to the longitudinal direction of the magnetic tape MT. Then, every time cylinder RB rotates 180°, each head HD
1. The HD 2 alternately contacts the magnetic tape MT for 90 degrees each time, and audio data is recorded on the magnetic tape or audio data is read from the magnetic tape.

In addition, in the R-DAT device, a clock generator built in the signal processing circuit 1 generates a signal CLC (T
is the rotation period), and a contact signal HTC is generated in synchronization with the contact between the head and the tape, and signal processing and recording/reproduction processing are performed in synchronization with this signal.

Furthermore, the R-DAT device uses subcode information to have search functions by song number, index, and absolute time. For example, when searching by song number, a desired song can be searched and the beginning of the song can be searched for, or an intro scan or other play can be performed at high speed. This search is performed at 200 times the tape feed speed during normal playback.

By the way, subcodes must be read during high-speed search. For this reason, it is necessary to keep the relative speed between the tape and the head constant, and the cylinder rotates at 3023 revolutions/min during fast forwarding (FF) (2000 revolutions during normal), and during rewinding (REW).
must rotate at 960 revolutions/min.

<Problems to be solved by the invention> Now, considering the rise in the tape feed speed during a search, it would be ideal for the tape feed speed to rise instantly to the target speed, but in reality, the tape speed is at a certain speed (for example, 200x speed). It will take some time for it to stabilize. Further, the rotational speed of the cylinder requires a certain period of time to rise to a relative speed at which data can be read. 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 data (subcode) can actually be read. In other words, data cannot be read for a certain period of time from the start of the search.

By the way, with the R-DAT device, 9 is displayed at the beginning of the song.
The start ID indicating the beginning of the song is recorded for every second.
When searching by song number, the start ID is used to cue, intro scan, and other plays.

For this reason, when searching for a track number from the current tape running position, depending on the current tape running position, the start ID of the next track may not be read due to the rise time. This causes malfunctions when playing.

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a speed control method that can keep the relative speed of the head and tape constant even at the start of a high-speed search, and therefore can read subcodes accurately even at the start of a search.

<Means for Solving the Problems> FIG. 1 is a block diagram of a speed control device according to the present invention.

11 is a counter, 12 is a tape speed data storage memory, 13 is a reel speed servo circuit, 14 is a cylinder speed data storage memory, and 15 is a cylinder speed servo circuit.

<Function> During a high-speed search, if the relative speed between the head and the tape can be kept constant during the speed rise period until the target speed is reached, data can be read during that period, and accurate searches can be performed.

Therefore, in the present invention, the time from the start of the search until reaching the target speed is divided into a plurality of times, and the correspondence between each time and the speed of the tape and cylinder at that time is determined to be constant.
During a high-speed search, the time from the start of the search is monitored by counting clock pulses with the counter 11, and the tape speed and cylinder speed at that time are determined from the memories 12 and 14, and the speed servo circuit 13 calculates the tape speed and cylinder speed at that time. .

<Embodiment> FIG. 1 is a block diagram of a speed control device that implements the speed control method according to the present invention.

11 is a 4-bit counter; 12 is a tape speed data storage memory; 13 is a reel speed servo circuit; 14 is a cylinder speed data storage memory;
5 is a cylinder speed servo circuit.

The counter 11 counts the clock pulses _PC after the search start signal SRS is generated, and monitors the time after the start of the search. Furthermore, the period of the clock pulse P _C is
It is 50msec.

The tape speed data storage memory 12 discretely stores the relationship between time and tape speed V _T in 16 stages from the search start time until the tape speed reaches the target speed.
4 stores the relationship between time and cylinder speed V _C discretely in 16 stages from the search start time until the cylinder speed reaches the target speed. Note that the tape speed and cylinder rotation speed at each time are determined so that the relative speed between the head and the tape is constant, and at the initial stage the tape is played back at a playback speed S (=8.15 mm/
S), and the cylinder is rotating at 2000 rpm.

Figure 2A shows the count value N of the counter 11, the tape speed V _T , and the cylinder rotation speed V _C during fast forwarding.
FIG. 2B is a correspondence table between the count value N of the counter 11 during rewinding, the tape speed V _T , and the cylinder rotation speed V _C . Count value N=1~
14, V _T and V _C can be any number as long as the relative speed is a constant value, but when N = 0, the tape speed V _T during fast forwarding and rewinding, and the cylinder rotation speed V _C are the speed S during normal playback. , 2000 rpm, and when N=15, V _T and V _C must be 200·S, 3023 rpm during fast forwarding, and 200·S, 960 rpm during rewinding.

When the performance of a certain song is finished and the next song is to be searched, a search start signal SRS is generated. After this search start signal SRS is generated, a clock pulse is generated.
When P _C occurs and N=1, the tape speed V _T and cylinder speed V _C at N=1 are set to the tape speed data storage memory 12 and the cylinder speed data storage memory 14, respectively, depending on fast forwarding or rewinding. The reel speed servo circuit 13
is output to the cylinder speed servo circuit 15.

As a result, the reel speed servo circuit 13 and the cylinder speed servo circuit 15 respectively control the tape speed and the cylinder rotation speed so that they become the target speeds. That is, when the tape runs due to the rotation of the reel, a pulse _PR is generated from a pulse generator (not shown) every time the tape moves for a predetermined time, and the pulse PR is fed back to the reel speed servo circuit 13, and the pulse _PR is fed back to the reel speed servo circuit 13. 13 controls the tape speed so that it becomes the commanded speed V _T .

On the other hand, when the cylinder rotates _, a pulse P _S is generated from a pulse generator (not shown) every predetermined rotation of the cylinder.
5, and the cylinder speed servo circuit 15 controls the cylinder rotational speed to the commanded speed V _C .

As a result of the above, the tape speed and cylinder rotational speed become the commanded speeds for a short time, during which time the relative speed between the head and the tape is kept constant.

In this state, when a clock pulse P _C is generated and the count value N of the counter 11 becomes 2, the tape speed V _T and cylinder speed V _C at N=2 are stored in the tape speed data storage memory 12 and the cylinder speed data storage memory, respectively. 14 and output to the reel speed servo circuit 13 and the cylinder speed servo circuit 15. Thereafter, under the same control as described above, the reel speed servo circuit 13 rotates the reel so that the tape speed becomes the command value V _T. Further, the cylinder speed servo circuit 15 rotates the cylinder to a commanded speed V _C .

From then on, the above speed control is performed until N=15, and finally the tape speed is 200 of the normal speed.
The cylinder speed is doubled in case of rapid traverse.
3023rpm, 960rpm when rewinding. still,
If the period of clock pulse P _C is 50 msec, then 50
After ×15 msec, the tape speed and cylinder rotational speed reach the target speed, and during that time the relative speed between the head and tape becomes approximately constant.

FIG. 3 is a block diagram of a speed control device according to another embodiment of the present invention, in which the same parts as in FIG. 1 are given the same reference numerals.

In the figure, 11 is a counter, 12 is a tape speed data storage memory, 13 is a reel speed servo circuit, 1
5 is a cylinder speed servo circuit, 21 is a tape speed measurement counter, and 22 is a cylinder speed data storage memory.

The tape speed measuring counter 21 counts pulses _PR generated from a pulse generator (not shown) for a predetermined time every time the tape moves by a predetermined distance, and generates digital data _DV corresponding to the actual tape speed.

The cylinder speed data storage memory 22 discretely stores the relationship between the tape speed V _T and the cylinder speed V _C for fast forwarding and rewinding, respectively. still,
The cylinder rotational speed corresponding to the tape speed is determined so that the relative speed of the head and tape is constant. Figure 4 A shows the tape speed during fast forwarding.
This is a correspondence table between V _T and cylinder speed V _C , and Fig. 4B
is a correspondence table between tape speed V _T and cylinder rotation speed V _C during rewinding.

When the performance of a certain song is finished and the next song is to be searched, a search start signal SRS is generated. After this search start signal SRS is generated, a clock pulse is generated.
When P _C occurs and N=1, the tape speed V _T at N=1 is read out from the tape speed data storage memory 12 and output to the reel speed servo circuit 13, depending on whether it is fast forward or rewind. Ru. This causes the reel speed servo circuit 13 to rotate the reel. When the tape runs due to the rotation of the reel, a pulse _PR is generated from a pulse generator (not shown) every time the tape moves for a predetermined time, and the pulse _PR is fed back to the reel speed servo circuit 13, and the reel speed servo circuit 13 command tape speed
Control the speed so that V _T.

Further, the pulse _PR generated by the pulse generator is input to a tape speed measuring counter 21, which counts the pulse _PR for a predetermined period of time and generates digital data _DV corresponding to the actual speed of the tape.
As a result, cylinder rotational speed data corresponding to the actual speed data D _V is stored in the cylinder speed storage memory 22.
V _C is read and cylinder speed servo circuit 15
is input, and the cylinder rotates. When the cylinder rotates, a pulse P _S is generated from a pulse generator (not shown) every predetermined rotation of the cylinder, and the pulse P _S is fed back to the cylinder speed servo circuit 15, which controls the cylinder at a commanded speed. Control the speed to match V _C.

As a result of the above, the tape speed and cylinder rotational speed become the commanded speeds within a short time.

In this state, when a clock pulse P _C is generated and the count value N of the counter 11 becomes 2, the tape speed V _T at N=2 is read out from the tape speed data storage memory 12 and output to the reel speed servo circuit 13. Thereafter, by the same control as described above, the reel speed servo circuit 13 rotates the reel so that the tape speed becomes the commanded value, and the cylinder speed servo circuit 15 rotates the cylinder so that the tape speed becomes the commanded speed.

From then on, the above speed control is performed until N=15, and finally the tape speed is 200 of the normal speed.
The cylinder speed is doubled in case of rapid traverse.
3023rpm, 960rpm when rewinding.

<Effects of the Invention> According to the present invention, the tape speed and cylinder speed are controlled in stages so that the relative speed between the head and the tape is constant at the start of a high-speed search. The relative speed between the head and the tape can be kept constant even when a search is started, so the subcode can be read accurately even at the start of a search, making it possible to perform a search accurately.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a speed control device according to the present invention, Fig. 2 is a diagram showing the correspondence between time, tape speed, and cylinder rotation speed, and Fig. 3 is a block diagram of a speed control device according to another embodiment of the present invention. , FIG. 4 is a chart showing the correspondence between tape speed and cylinder rotation speed, and FIGS. 5 and 6 are explanatory diagrams of the R-DAT device. 11... Counter, 12... Tape speed data storage memory, 13... Reel speed servo circuit, 1
4... Cylinder speed data storage memory, 15...
Cylinder speed servo circuit, 21... Tape speed measurement counter, 22... Cylinder speed data storage memory.

Claims (1)

[Scope of Claims] 1. A digital audio system that records signals on the magnetic tape by feeding the magnetic tape in the longitudinal direction of the tape and rotating the head while tilting the tape with respect to the longitudinal direction of the tape, or reads and reproduces signals from the magnetic tape. In a speed control method during a high-speed search of a tape device, the time from the start of the search until the target speed is reached for one of the magnetic tape start-up speed and head start-up rotation speed is divided into multiple periods and each time is set. and the desired speed at that time is stored in a memory, and during a high-speed search, the time from the start of the search is monitored, the desired speed at that time is determined from the memory, and the command is given to the speed servo circuit. The speed is controlled step by step up to the target speed, and for the other speed, the correspondence between the time from the start of the search and the desired speed at that time is discretely stored in the memory, and the desired speed at the current time is retrieved from the memory. 1. A speed control method, comprising: determining the desired speed, and instructing a speed servo circuit to control the speed in stages. 2. During high-speed search of a digital audio tape device that records signals on the magnetic tape by feeding the magnetic tape in the longitudinal direction of the tape and rotates the head while tilting it with respect to the longitudinal direction of the tape, or reads and reproduces signals from the magnetic tape. In the speed control method, one of the magnetic tape start-up feed speed and the head start-up rotation speed,
The time from the start of the search until reaching the target speed is divided into multiple parts, and the correspondence between each time and the desired speed at that time is stored in memory, and during high-speed search, the time from the start of the search is monitored and the corresponding By determining the desired speed at the time from the memory and instructing the speed servo circuit, the speed is controlled step by step up to the target speed, and regarding the other speed, the correspondence relationship between the one speed and the other speed is determined. is stored in the memory, the actual speed of the one is detected, the speed of the other corresponding to the actual speed is determined from the memory, and the speed of the other is set as the target speed by commanding the speed servo circuit of the other. A speed control method characterized by stepwise control.