JPH0344853A - Reel servo control system for high-speed search - Google Patents

Abstract

PURPOSE:To smoothly rise tape velocity even when the load of a tape driving system is fluctuated by comparing the tape velocity with prescribed reference velocity when high-speed search is started and applying a driving voltage, which is in proportion to the difference of the velocity, to a reel motor. CONSTITUTION:A system controller 1, reel servo circuit 2, motor driver 3, reel motor 4, and revolution detector (FG) 5 to detect the revolution of the reel motor are provided. When the high-speed search is started, the tape velocity is compared with the prescribed reference velocity and the driving voltage in proportion to the difference of the velocity is applied to the reel motor 4. After the reel motor 4 starts revolution, a ramp voltage is impressed to be increased at a fixed inclined angle, which is determined in advance, toward the specified final search velocity. Thus, when the high-speed search is started, the tape velocity is prevented from being rapidly fluctuated even in case the load of the tape driving system is fluctuated.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a rotary head type digital magnetic recording/reproducing device,
The present invention relates to a road servo control method for high-speed search in a so-called digital audio tape recorder (hereinafter referred to as rDATJ).

[Conventional technology]

One of the characteristic functions of DAT is high-speed search. When performing this high-speed search, it is necessary to always control the relative speed of the tape and drum to be constant so that the reproduced clock extracted from the RF reproduction signal is the same as during normal running (REC/PLAY).

By the way, when performing this high-speed search, it is necessary to start up the tape from speed O to a specified high speed, for example, 200x speed, at the same time as the search starts. A method has been adopted in which a so-called ramp voltage is applied to the reel motor, in which the voltage increases at a predetermined constant angle of inclination toward the reel motor.

FIG. 3 shows an example of a conventional reel servo circuit for high-speed searching constructed by employing the reel servo control method using the above-mentioned lamp voltage. In the figure, 31 is a system controller consisting of a microcomputer, 32 is a reel servo circuit, 33 is a motor driver, and 34 is a reel motor, which is used by the user to select a predetermined song by pressing a search button (not shown). When a search command is given, the system controller 31 sends a search start signal to the reel servo circuit 32. When the reel servo circuit 32 receives this high-speed search start command, as shown in FIG. 4(a), the voltage increases at a predetermined constant inclination angle toward a specified final search speed, for example, 200 times the speed. The lamp voltage is output, the reel motor 34 is rotationally driven through the motor driver 33, and the rotational speed of the reel motor, that is, the tape speed is increased to a prescribed 200 times speed along the slope of the lamp voltage.

(Problems to be Solved by the Invention) When using the above-mentioned conventional glue servo control method, if there is no load fluctuation in the tape drive system, the tape speed will be lower than the reel as shown by the dotted line in FIG. rises smoothly along the ramp voltage applied to the motor 34. However,
If the load on the tape drive system fluctuates before the reel motor 34 starts moving, the tape speed will not increase smoothly along the ramp voltage, as shown by the solid line in FIG. It may happen that the engine suddenly starts rotating from a position where the balance between the load fluctuation and rotational torque is broken.

As mentioned above, if the tape speed changes suddenly at the start of a high-speed search, the drum rotation speed, which is controlled so that the relative speed with the reel motor is constant, will not be able to follow this sudden change. , a predetermined reproduced clock cannot be extracted from the RF regenerated signal, and a search cannot be performed during this period of fluctuation.

For example, if a search command for the next song is given at a position close to the next song between the current song and the next song, and the above problem occurs while the tape speed is ramping up, the tape will pass during the ramp. A situation may occur in which the start ID of the next song cannot be read and the song is skipped over, and the next song, that is, the second song, is mistakenly searched as the next song.

In addition, during high-speed search, the tape is temporarily stopped and then transferred to high-speed running state due to the need to change the gear ratio of the reel, so the above problem may occur even if a high-speed search command is given during playback operation. obtain.

The present invention was made to solve the above problems, and
To provide a reel servo control system for a high-speed search that prevents the tape speed from rapidly changing even if the load on a tape drive system changes at the start of the high-speed search.

[Means for Solving the Problems] In order to achieve the above object, the glue servo control system of the present invention compares the tape speed with a predetermined reference speed at the start of a high-speed search, and performs a drive proportional to the speed difference. After a voltage is applied to the reel motor and the reel motor starts rotating, a ramp voltage is applied that increases at a predetermined constant angle of inclination toward a specified final search speed.

[For production]

Simultaneously with the start of the high-speed search, the tape speed is compared with a prescribed reference speed, and a drive voltage proportional to the speed difference is applied to the reel motor.

At the start of this high-speed search, the reel motor is in a stopped state, so the tape speed is O, the speed difference from the reference speed is maximum, the maximum drive voltage is applied to the reel motor, and the reel motor is at maximum torque. The drive is started by. As a result, even if load fluctuation occurs in the tape drive system, the reel motor starts rotating smoothly at the same time as the high-speed search starts. Therefore, since the rotational speed of the reel motor, that is, the tape speed increases smoothly, it is possible to follow this and accurately control the speed of the drum so that the relative speed remains constant, even when starting a high-speed search. The recovered clock can be extracted and high-speed searches can be performed effectively.

Once the reel motor has started rotating as described above, load fluctuations in the tape drive system will no longer have an extreme effect on the tape speed, and the reel motor will be driven by the ramp voltage as in the past. All you have to do is start up towards the final search speed of .

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of a reel servo circuit for high-speed searching constructed by applying the reel servo control system of the present invention.

In the figure, ■ is a system controller consisting of a microcomputer, 2 is a reel servo circuit, 3 is a motor driver, 4 is a reel motor, and 5 is a rotation speed detector (FG) that detects the rotation speed of the reel motor. The reel servo circuit 2 includes a lamp voltage control circuit 21 that outputs a lamp voltage that increases at a predetermined inclination angle, and a speed control circuit that controls the tape speed according to the rotation speed of the reel motor 4 detected by the rotation speed detector 5. 22, and a changeover switch 23 for selectively switching the drive of the reel motor between speed control and lamp voltage control. The speed control circuit 22 is
An F-V converter 24 that converts the rotation speed of the reel motor 4 detected by the rotation speed detector 5 into a voltage proportional to the rotation speed of the reel motor 4;
A subtracter 25 that compares the converted voltage of the V converter 24 and the reference speed voltage VREF and outputs the difference voltage as a drive voltage.
It is composed of.

The operation will now be explained with reference to FIG.

When the user presses a search button (not shown) to issue a search command, the system controller I sends a search start signal to the reel servo circuit 2 as in the conventional case.

The reel servo circuit 2 receives this search start signal, sets the changeover switch 23 to the speed control circuit 22 side, and starts driving the reel motor 4.

The rotation speed detector 5 detects the rotation speed of the reel motor 4,
The F-V converter 24 is manually operated. Since the rotational speed of the reel motor 4 is 0 at the start of the search, the F-V conversion device 24
The output voltage of is O. Therefore, at the same time as the start of the high-speed search, the subtracter 25 outputs the reference speed voltage V REF as it is as the drive voltage, and the reel motor 4
As shown in FIG. 2(a), driving is started at the maximum driving voltage. As a result, the rotational torque of the reel motor reaches its maximum at the same time as the high-speed search starts, and even if the load on the tape drive system fluctuates, the rotational speed of the reel motor 4, that is, the tape speed, remains as shown in FIG. 2(b). , starts to rise smoothly.

The increase in the rotational speed of the reel motor 4 is detected by the rotational speed detector 5, converted into a voltage proportional to the rotational speed by the F-V converter 24, and sent to the subtracter 25. As a result, the output voltage of the subtracter 2 decreases as the tape speed increases, as shown in FIG. 2(a), and the speed of the reel motor 4 is controlled so as not to change suddenly.

When the reel motor 4 starts rotating as described above and reaches a predetermined tape speed, for example, 1x speed, the reel servo circuit 2 switches the changeover switch 23 from the speed control circuit 22 side to the ramp control circuit 21 side. After this, as shown in FIG. 2(a), a ramp voltage having a predetermined constant inclination angle is applied to drive the reel motor 4 toward a specified final search speed, for example, 200 times the speed.

Therefore, as shown in Figure 2 (b), the tape speed increases smoothly from the start of the high-speed search to 200 times the speed, and the relative speed between the tape and the drum can always be maintained at a constant value. .

〔Effect of the invention〕

As is clear from the above, when using the reel servo control method of the present invention, at the start of a high-speed search, the tape speed is compared with a predetermined reference speed, and a drive voltage proportional to the speed difference is applied to the reel motor. After the reel motor starts rotating, a ramp voltage is applied that increases at a predetermined constant inclination angle toward the specified final search speed. Even if the load on the tape varies, the tape speed can be smoothly increased regardless of this, and accurate search can be achieved over the entire high-speed search range.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment of a high-speed reel servo circuit constructed by applying the method of the present invention, Fig. 2 is an explanatory diagram of the operation of the same embodiment, Fig. 3 is a block diagram of a conventional example, and Fig. 4 The figure is an explanatory diagram of the operation of the conventional example. DESCRIPTION OF SYMBOLS 1... System controller, 2... Reel servo circuit, 3... Reel driver, 4... Reel motor, 5... Rotation speed detector, 21... Lamp voltage control circuit, 22...・Speed control circuit, 23...Switch switch, 24...F-V converter, 25...Subtractor, V
IIEF...Reference speed voltage.

Claims (1)

[Claims] In a rotary head type digital magnetic recording and reproducing device, at the start of a high-speed search, the tape speed is compared with a predetermined reference speed, and a drive voltage proportional to the speed difference is applied to the reel motor. A reel servo control system for high-speed search, characterized in that after the reel starts rotating, a ramp voltage is applied that increases at a predetermined constant angle of inclination toward a specified final search speed.