JPH05314597A - Reproducing device for digital signal - Google Patents

Abstract

PURPOSE:To miniaturize and reduce the cost of the mechanical deck in an R-DAT, etc. CONSTITUTION:The subject device is the reproducing device to reproduce digital data from a magnetic tape 2 in which an address signal is recorded together with the digital data. A reproduction processing circuit 15 to reproduce an original signal from the digital data is provided. A take-up motor 21 to take up a magnetic tape is provided. A circuit 22 (and 30) to detect the rotation cycle of a take-up hub 3T taking up the magnetic tape 2 is provided. A speed control loop to control the rotation of take-up motor 21 so that the rotation cycle of the take-up hub 3T becomes a prescribed value, is provided. A phase control loop to control the rotation of take-up motor 21 so that the changing speed of address signal becomes a standard changing speed regardless of the reproducing position of magnetic tape 2, is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal reproducing apparatus such as R-DAT.

[0002]

2. Description of the Related Art In a general R-DAT, a magnetic tape is driven by a so-called capstan drive system like an analog tape recorder, and a tape is run at a constant speed by a capstan and a pinch roller. At the same time, the tape is taken up by a take-up hub (take-up reel).

Reference: Illustrated DAT Reader (Ohm Company 1988
Issued on July 25, etc.)

[0004]

However, the capstan drive system requires a mechanism for pressing the tape to the capstan by a pinch roller during reproduction. Moreover, the crimping mechanism, the capstan, and the pinch roller must not interfere with the attachment / detachment of the tape cassette.

Further, while the tape speed is constant during reproduction, the winding diameter of the tape of the take-up hub gradually increases with the playing time, so that the rotation speed of the take-up hub is the same as that of the take-up diameter. It must be gradually delayed in response. Also, the winding torque of the tape must be constant. Further, it is necessary to wind the tape at high speed during fast-forwarding. That is, a winding mechanism that satisfies these winding conditions is also required.

[0006] For the above reasons, it is difficult to reduce the size and cost of the mechanical deck in the R-DAT, and a headphone stereo such as Walkman (registered trademark), that is, a sufficiently small size is used. Lightweight, affordable digital headphone stereos are in a state where they cannot be put to practical use.

The present invention solves these problems,
It is intended to realize digital headphone stereo.

[0008]

Therefore, in the present invention, the tape is driven by a so-called reel drive in which the winding hub is rotated without using the capstan and the pinch roller.

At this time, a speed servo is applied to the take-up motor (reel motor) to rotate the take-up hub at a standard speed. However, with this alone, the winding diameter of the take-up hub increases as the tape runs. Since the tape speed gradually increases and the tape speed increases, phase servo is applied using the frame address recorded on the tape (details will be described later) to keep the tape speed constant.

That is, when the reference numerals of the respective parts are made to correspond to the embodiments described later, in the reproducing device for reproducing the digital data from the magnetic tape 2 on which the address signal FADR is recorded together with the digital data, the original data from the digital data is reproduced. A reproduction processing circuit 15 for reproducing a signal and a magnetic tape 2
Winding motor 21 for winding the tape and magnetic tape 2
Circuit 22, 31-33 that detects the rotation cycle of the winding hub 3T that winds the winding hub, and a speed control loop that controls the rotation of the winding motor 21 so that the rotation cycle of the winding hub 3T becomes a predetermined value. 40 and the changing speed of the address signal FADR regardless of the reproducing position of the magnetic tape 2,
A phase control loop 50 for controlling the rotation of the winding motor 21 is provided so as to obtain a standard change speed.

[0011]

The magnetic tape 2 is reel-driven by the winding motor 21 and runs. At this time, the tape speed is ensured by the speed control loop 40, and the tape speed is maintained at the standard value by the phase control loop 50 using the frame signal FADR.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, 1 is an R-DAT tape cassette, 2 is its magnetic tape, 3S is a supply hub, and 3 is a supply hub.
T is a winding hub. And in this figure,
For reproduction, the tape 2 is pulled out from the hub 3S to the outside of the cassette 1, circulated around a rotary magnetic head device 11 described later over a predetermined angular range, and then wound on a winding hub 3T.

In this case, the audio signal is recorded on the tape 2 in a track pattern as shown in FIG. 3, for example. That is, in FIG. 3, An, Bn
(N = 0, 1, 2, 3, ...) Denote magnetic tracks, and these tracks An and Bn are formed obliquely to the tape 2 and adjacent to each other. Further, the tracks An and Bn are formed at a rate of 200 lines / 3 seconds, and the track An and the track Bn are
The azimuth angles are opposite to each other.

An arbitrary track Ai and the next track Bi are paired, and the pair of tracks Ai,
One frame of digital audio data is recorded in Bi in a predetermined signal format. In this case, the tracks An and Bn are formed at a rate of 200 lines / 3 seconds, and since one pair of tracks Ai and Bi have digital audio data for one frame, it becomes 100 frames / 3 seconds, which is one frame period. Will be 30 ms.

A frame address FADR indicating the order or number of the frame is added to the digital audio data of the tracks An and Bn for each frame. However, this frame address FADR is represented by 4 bits, and the value of 0 to 15 is repeated for each frame.

Further details and specific numerical values of the tracks An and Bn are not related to the essence of the present invention and are shown in the above-mentioned document. Bn can be formed as follows, for example.

That is, in the recording system, two rotary magnetic heads A and B have a rotary diameter of 30 mm and
It is installed with an angular interval of ° and is rotated at a rate of 2000 rpm. Then, the magnetic tape 2 is slanted around the rotating peripheral surfaces of the heads A and B over an angular range of slightly over 90 ° and is run at a speed of 8.15 mm / sec. Then, these are tapes 2 on the heads A and B.
Digital audio data is 1 while scanning
It is supplied frame by frame.

With the above arrangement, the digital audio data can be recorded on the tape 2 in the track pattern shown in FIG. The rotation diameter, the number of rotations, and the tape winding angle of the rotary head described above are standard values.

In the rotary magnetic head device 11 of the reproducing apparatus shown in FIG. 1, for example, as shown in FIG.
Two rotary magnetic heads 11A and 11B are provided with a rotation diameter of 15 mm and an angular interval of 180 °, and are rotated at a rate of 4000 rpm. The rotational diameter and the rotational speed of the heads 11A and 11B are 1/2 times and 2 times the standard values of the recording system described above.
Further, if the number of rotation diameters and the number of rotations are such, the scanning speed of the heads 11A and 11B is equal to the scanning speed of the standard head of the recording system.

Further, the azimuth angles of the heads 11A and 11B are made equal to those of the tracks An and Bn, and the track width of the heads 11A and 11B is the track A.
For example, it is set to 150% of that of n and Bn.

Then, such rotary heads 11A, 1
The tape 2 described with reference to FIG.
However, the tape 2 is slanted over a range of more than 180 °, and the tape 2 is run at a tape speed equal to that at the time of recording, that is, 8.15 mm / sec by a tape drive system described later.

Therefore, the tracks An and Bn and the reproduction signals of the heads 11A and 11B have a relationship as shown in FIG. 5, for example. That is, FIG. 5A shows a state in which a plurality of tapes 2 are arranged so that equal tracks Ai and Bi are continuous in the width direction of the tape 2. Then, tape 2
Is traveling at a speed equal to that at the time of recording, the scanning loci of the heads 11A and 11B are represented by the symbols Ha and Hb in FIG. 5A.
As shown by, while tilting with respect to the tracks An and Bn, each time the heads 11A and 11B rotate once,
The tape is shifted in the direction opposite to the tape running direction for each track.

At this time, the heads 11A and 11B are located in the shaded areas of the scanning loci Ha and Hb.
Since the azimuth angle of the track An and the azimuth angle of the tracks An and Bn are equal, this hatched area serves as a signal for the head 11.
Reproduced by A and 11B.

Therefore, if the reproduction signal of the heads 11A and 11B is a signal S11, the signal S11 becomes as shown in FIG. 5B, and the digital audio data recorded on the tracks An and Bn are recorded on the heads 11A and 11B. Playback is repeated twice with two rotations as a unit or cycle, and the reproduction is performed while changing the level as shown in FIG. 5B.

The reproduced signal S11 is supplied to the PCM equalizer circuit 13 through the head amplifier 12 for waveform equalization, and the waveform-equalized signal S11 is supplied to the digital signal reproduction processing circuit 15 through the limiter 14. , In this processing circuit 15, the heads 11A, 11B
Of the reproduced signal S11, reproduction processing such as 10-8 demodulation, deinterleaving, error correction and error correction is performed using an appropriate portion to reproduce the original digital audio signal and subcode.

Then, the reproduced original digital audio signal is supplied to the D / A converter 16 to be converted into the original left and right channel analog audio signals.
/ A converted, this analog audio signal is terminal 17
It is taken out to L and 17R.

In the present invention, the tape 2 is run by the reel drive. Therefore, the tape drive system is constructed as follows.

That is, 21 indicates a winding motor,
The motor 21 is rotatably coupled to the winding hub 3T, and is rotationally coupled to the hub 3T or the motor 21 to provide a frequency generator 22. From the frequency generator 22, the frequency of the winding hub 3T is increased. An alternating signal S22 having a frequency corresponding to the rotation speed is taken out, and this signal S22 is supplied to a shaping circuit 23 and shaped into a rectangular wave signal S23 as shown in FIG. 6A, for example.

Reference numeral 30 represents a microcomputer. The details of the microcomputer 30 are shown in FIG. 2, but in FIG. 2, the processing contents (software) are equivalently shown by hardware. However, the circuits 31 to 33 are hardware built in the microcomputer 30.

Then, in the clock forming circuit 31,
A clock CK with a predetermined frequency is formed, and this clock CK
Is supplied to the counter 32 as its count input, and the signal S23 from the shaping circuit 23 is supplied to the counter 32.
Are supplied as reset signals.

Therefore, the counter 32 has the clock CK.
Is counted and reset at each rising edge of the signal S23, the count value C32 of the count 32 changes at the period τ of the signal S23, as shown in FIG. 6B, and the count value CTAU immediately before resetting. Indicates the period τ of the signal S23, that is, the rotation period of the winding hub 3T.

Therefore, the speed servo is performed by the speed control loop 40 using the count value CTAU. That is, the count value C32 of the counter 32 is supplied to the latch 33, and the signal S23 is supplied to the latch 33 as a latch signal. Although not shown, the counter 32
The signal S23, which is supplied as a reset signal to S1, is slightly delayed.

Therefore, the count value C of the counter 32
32 is latched in the latch 33 by the signal S23 and the counter 32 is reset by the signal S23 immediately after the latching. Therefore, the latch 33 counts the count value CTAU indicating the period τ at each rising edge of the signal S23. Will be latched.

Then, the count value CTAU of the latch 33
Is supplied to the subtraction circuit 41, the reference value CREF is extracted from the signal forming circuit 42, and the reference value CREF is supplied to the subtraction circuit 41. In this case, this reference value CREF
Is, for example, a value equal to the count value CTAU when the beginning of the tape 2 is running at the same speed as when recording.

Therefore, the subtraction circuit 41 provides a signal S41 indicating the speed error of the running speed of the tape 2 (strictly speaking, the speed of the tape speed when the beginning of the tape 2 is being reproduced. A signal S41 indicating an error is output). If there is no speed error, S41 = 0.

The speed error signal S41 is supplied to the adder circuit 44 through the multiplier circuit 43 having a multiplier of K1, and the multiplier circuit 45 and the adder circuit 46 having a multiplier of K2.
Is supplied to the integration circuit 47 through and integrated, and the integrated output is supplied to the addition circuit 44.

Thus, the signal S41 is output from the adding circuit 44.
The filtered signal S44 is taken out, this signal S44 is supplied to the PWM modulation circuit 48 as its modulation signal, and the PWM signal S48 modulated by the signal S44 is taken out, and this signal S48 is sent to the low-pass filter 61. The DC voltage V61 is supplied, the carrier component is removed, and the level changes in response to the signal S44. This voltage V61 is supplied to the motor 21 through the drive circuit 62 as its drive voltage.

Therefore, the motor 21 is driven so that S41 = 0 with reference to the reference value CREF, and at this time, if the beginning is reproduced, the tape 2 is made to run at the same speed as that at the time of recording. It will be.

However, with the above speed control loop 40 alone, the tape 2 travels at the same speed as at the time of recording at the beginning according to the reference value CREF, but as the tape 2 travels, the tape winding diameter of the hub 3T increases. As it gets bigger, the tape speed gets faster.

For this reason, the phase control loop 50 is provided, and the tape 2 is phase-servoed so as to run at the same speed as that at the time of recording, other than at the beginning. That is, in the reproduction processing circuit 15, for example, as shown in FIG. 5C, the frame address FA which changes every frame period
DR is playing. Further, in the reproduction processing circuit 15, by counting the oscillation signals of the crystal oscillation circuit, a frame address FREF that changes at the reference frame frequency is formed and used, for example, as shown in FIG. 5D. The reference frame address FREF is also represented by 4 bits, and the value of 0 to 15 is repeated for each frame.

Therefore, the difference ΔFA ΔAR = FADR−FREF between the reproduction frame address FADR and the reference frame address FREF is extracted from the reproduction processing circuit 15. In this case, both frame addresses
Since FREF and FADR can only take values from 0 to 15, for example FA
In the next frame where DR = 15, the sign of the difference ΔAR is inverted due to FADR = 0, but when such a sign inversion occurs, for example, by adding a value 16 Values shall be corrected.

Therefore, if the difference ΔAR is constant, the reproduction frame address FADR changes at the standard speed and is synchronized with the reference frame address FREF, which is the same as when the tape 2 was recorded. Indicates that you are traveling at speed.

Therefore, the difference ΔAR is taken out from the reproduction processing circuit 15 as frame error data, the taken difference ΔAR is supplied to the subtraction circuit 51, and the offset value OFST is taken out from the signal forming circuit 52. , The offset value OFST is supplied to the subtraction circuit 51,
From the subtraction circuit 51, the frame error signal S51 represented by S51 = ΔAR-OFST is taken out.

In this case, if the tape 2 is running at the same speed as during recording, the difference ΔAR is constant, so the error signal S51 is constant, and the tape 2 is running at a speed different from that during recording. If the difference ΔAR changes, the error signal S
51 also changes. That is, when S51 = 0, the tape speed is equal to that during recording. When S51> 0, the tape speed is faster than during recording. When S51 <0, the tape speed is lower than during recording.

Therefore, the frame error signal S51 is supplied to the addition circuit 54 through the multiplication circuit 53 having a multiplier of K3, and is also supplied to the integration circuit 56 through the multiplication circuit 55 having a multiplier of K4 to be integrated and the integrated output thereof. Are supplied to the adder circuit 54.

In this way, from the adder circuit 54, the filtered signal S54 of the frame error signal S51 is taken out, and this signal S54 is supplied to the adder circuit 46.

Therefore, the rotation speed of the motor 21 is controlled so that S51 = 0, that is, the reproduction frame address FADR is synchronized with the reference frame address FREF. Then, during S51 = 0, the speed control loop 40 maintains the rotational speed of the motor 21 at that time. Therefore, at this time, the tape 2 is run at the same speed as at the time of recording.

Thus, according to the present invention, when the tape 2 is reproduced, a capstan drive mechanism, that is, a capstan, a capstan motor, a pinch roller, a pinch roller crimping mechanism, etc., is completely unnecessary. Since the capstan and the pinch roller do not hinder the attachment / detachment of the cassette 1, the mechanical deck can be downsized and the cost can be reduced.

Further, reproduction, stop, fast-forward or high-speed search can be realized only by rotating, stopping or rotating the motor 21 at high speed. Moreover, in order to control the rotation of the motor 21 in this way, it is only necessary to change the drive voltage supplied to the motor 21. From this point as well, the mechanical deck can be downsized and the cost can be reduced.

By the way, in the above example, the reference value CREF supplied to the subtraction circuit 41 is a fixed value, for example, the count value CTAU when the beginning of the tape 2 is running at the same speed as during recording. Are equal. Therefore, when the reproduction is started from the middle of the tape 2, the speed error signal S41 is considerably large, and the phase control loop 50 changes the tape speed while the speed control loop 40 is operating by the signal S41. Since it has to be controlled to the standard value, it may take some time until the tape speed reaches the standard value, that is, the tape 2 is properly reproduced.

In the example shown in FIG. 7, such a point is taken into consideration. That is, from the reproduction processing circuit 15, the data ABST indicating the absolute time recorded on the tape 2 (the start time of the tape 2 is 0 second and the time thereafter increases according to the running time of the tape 2) is taken out, This data ABST is supplied to the signal forming circuit 42, and from the forming circuit 42, the reference value CRE that changes corresponding to the data ABST.
F, that is, a reference value CREF that increases as the tape 2 runs is taken out. Then, the reference value CREF is supplied to the subtraction circuit 41.

Therefore, the reference value CREF is always tape 2
Since it becomes a value suitable for the playback position of, it is possible to shorten the time until the tape speed reaches the standard value regardless of the position where the tape 2 is played, and when the playback button is pressed,
Immediately, the tape 2 is correctly reproduced.

In the above description, the motor 21 may be used both for the winding hub 3T and the supply hub 3S. Also, the circuits 31 to 33 can be realized by software to obtain the value CTAU indicating the period τ. further,
Any signal or data other than the absolute time data ABST can be used as long as it is a signal indicating the absolute reproduction position of the tape 2.

[0054]

According to the present invention, when the tape 2 is reproduced, a capstan drive mechanism, that is, a capstan, a capstan motor, a pinch roller, a pinch roller crimping mechanism, etc., is completely unnecessary. Since the capstan and the pinch roller do not hinder the attachment / detachment of the cassette 1, the mechanical deck can be downsized and the cost can be reduced.

Further, reproduction, stop, fast-forward or high-speed search can be realized only by rotating, stopping or rotating the motor 21 at high speed. Moreover, in order to control the rotation of the motor 21 in this way, it is only necessary to change the drive voltage supplied to the motor 21. From this point as well, the mechanical deck can be downsized and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a system diagram showing an example of the present invention.

FIG. 2 is an equivalent circuit diagram showing a part of FIG.

FIG. 3 is a diagram showing a track pattern.

FIG. 4 is a plan view for explaining a rotary magnetic head.

FIG. 5 is a diagram showing a relationship between a scanning locus of a head and a signal.

FIG. 6 is a waveform diagram when detecting the rotation cycle of the winding hub.

FIG. 7 is a system diagram showing another example of the present invention.

[Explanation of symbols]

 1 R-DAT cassette 2 Magnetic tape 3S Supply hub 3T Winding hub 11 Rotary magnetic head device 11A, 11B Rotary magnetic head 15 Digital reproduction processing circuit 16 D / A converter 21 Winding motor 22 Frequency generator 30 Microcomputer 32 Counter 33 Latch 40 Speed control loop 48 PWM modulation circuit 50 Phase control loop 61 Low pass filter 62 Drive circuit

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 5, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction content]

A frame address FADR indicating the order or number of the frame is added to the digital audio data of the tracks An and Bn for each frame. However, this frame address FADR is expressed by 4 bits, and the range of values 0 to 15 is repeated for each frame.
You change.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

[0018] With the above, the tape 2, 3
Digital audio data can be recorded with the track pattern shown in. The rotation diameter, the number of rotations, and the tape winding angle of the rotary head described above are standard values.

[Procedure 3]

[Document name to be amended] Statement

[Item name to be corrected] 0040

[Correction method] Change

[Correction content]

For this reason, the phase control loop 50 is provided, and the tape 2 is phase-servoed so as to run at the same speed as that at the time of recording, other than at the beginning. That is, in the reproduction processing circuit 15, for example, as shown in FIG. 5C, the frame address FA which changes every frame period
DR is playing. Further, in the reproduction processing circuit 15, by counting the oscillation signals of the crystal oscillation circuit, a frame address FREF that changes at the reference frame frequency is formed and used, as shown in FIG. 5D, for example. The reference frame address FREF is also expressed in 4 bits, you then <br/> Rikae Repetitive a range of values 0 to 15 for each frame changes.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0043

[Correction method] Change

[Correction content]

Therefore, the difference ΔAR is taken out from the reproduction processing circuit 15 as frame error data, the taken difference ΔAR is supplied to the subtraction circuit 51, and the offset value OFST is taken out from the signal forming circuit 52. , The offset value OFST is supplied to the subtraction circuit 51,
The frame error signal S51 represented by S51 = OFST-ΔAR is taken out from the subtraction circuit 51.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0044

[Correction method] Change

[Correction content]

In this case, if the tape 2 is running at the same speed as during recording, the difference ΔAR is constant, so the error signal S51 is constant, and the tape 2 is running at a speed different from that during recording. If the difference ΔAR changes, the error signal S
51 also changes. That is, when S51 = 0, the tape speed is equal to that during recording. When S51 < 0, the tape speed is faster than during recording. When S51 > 0, the tape speed is slower than during recording.

[Procedure Amendment 6]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

Claims (4)

[Claims] 1. A reproducing apparatus for reproducing the digital data from a magnetic tape on which an address signal is recorded together with the digital data, and a reproducing processing circuit for reproducing the original signal from the digital data, and a winding of the magnetic tape. A winding motor for winding, a circuit for detecting the rotation cycle of the winding hub for winding the magnetic tape, and rotation of the winding motor so that the rotation cycle of the winding hub becomes a predetermined value. Regardless of the speed control loop to control and the reproduction position of the magnetic tape, the changing speed of the address signal becomes a standard changing speed.
A digital signal reproducing apparatus having a phase control loop for controlling the rotation of the winding motor. 2. A reproducing apparatus for reproducing the digital data from the magnetic tape on which an address signal is recorded together with the digital data, and a reproducing processing circuit for reproducing the original signal from the digital data, and winding the magnetic tape. A winding motor for winding, a circuit for detecting the rotation cycle of the winding hub for winding the magnetic tape, a circuit for comparing the rotation cycle of the winding hub with a reference value of this rotation cycle, A circuit for controlling the rotation of the winding motor, a circuit for comparing the address signal with a reference address signal so that the comparison result becomes a predetermined constant value, and the comparison result is the magnetic tape. Of a digital signal having a circuit for controlling the rotation of the winding motor so as to have a predetermined constant value regardless of the reproduction position of Location. 3. A reproducing apparatus for reproducing the digital data from a magnetic tape on which an address signal is recorded together with the digital data, and a reproducing processing circuit for reproducing the original signal from the digital data, and winding the magnetic tape. A winding motor for winding, a circuit for detecting the rotation cycle of the winding hub for winding the magnetic tape, and rotation of the winding motor so that the rotation cycle of the winding hub becomes a predetermined value. A speed control loop for controlling, a circuit for changing the reference value in the speed control loop corresponding to the absolute reproduction position of the magnetic tape, and a speed at which the address signal changes regardless of the reproduction position of the magnetic tape. So that the standard rate of change is
A digital signal reproducing apparatus having a phase control loop for controlling the rotation of the winding motor. 4. A reproducing apparatus for reproducing the digital data from the magnetic tape on which an address signal is recorded together with the digital data, and a reproducing processing circuit for reproducing the original signal from the digital data, and winding the magnetic tape. A winding motor for winding, a circuit for detecting the rotation cycle of the winding hub for winding the magnetic tape, a circuit for extracting a signal indicating the absolute reproduction position of the magnetic tape, and an absolute circuit for the magnetic tape. A circuit that forms data indicating the rotation cycle of the winding hub at the reproduction position, a rotation cycle of the winding hub, and data indicating the rotation cycle of the winding hub from a signal indicating a specific reproduction position. A circuit for comparison, a circuit for controlling the rotation of the winding motor so that the comparison result becomes a predetermined constant value, Circuit for comparing a response signal with a reference address signal, and a circuit for controlling the rotation of the winding motor such that the comparison result becomes a predetermined constant value regardless of the reproducing position of the magnetic tape. And a digital signal reproducing apparatus having.