JPH0544905Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial field of application> The present invention relates to a fast-forwarding speed control device, and is particularly applicable to high-speed searches in digital audiotape devices.
The present invention relates to a fast forwarding speed control device suitable for application to FF fast forwarding, REW rewinding, etc.

<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).

As shown in FIG. 7, the rotating head configuration used in such an R-DAT device includes two heads HD1 and HD2 for both recording and playback, which are arranged at an interval of 180 degrees from each other on a rotating body (cylinder) RB. The relative positional relationship between the magnetic tape and each head is determined so that the running trajectory of each head HD1, HD2 on the surface of the magnetic tape MT is inclined with respect to the longitudinal direction of the magnetic tape MT. And cylinder RB is
Each time the heads HD1 and HD2 rotate by 180 degrees, each head HD1 and HD2 alternately contacts the magnetic tape MT for 90 degrees each time, so that 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) synchronized with the rotation of the cylinder (rotating head) shown in Fig. A synchronized contact signal HTC is generated, and signal processing and recording/reproduction processing are performed in synchronization with the 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.

<The problem that the invention is trying to solve> Now, if the relative speed between the tape and the head fluctuates, it becomes impossible to read the subcode accurately. For this reason, the tape feed speed and cylinder rotation speed are each servo-controlled so that the relative speed does not fluctuate.

By the way, in conventional tape feed speed control, a pulse generator is provided that comes into contact with the tape, and each time the tape moves by a predetermined amount, the pulse generator generates one pulse to generate a pulse train corresponding to the actual speed. The pulse train is used to generate a speed error signal corresponding to the difference between the actual speed and the commanded speed to control the tape feeding speed.

However, such a tape contact type pulse generator may cause slippage or poor contact, and there is a problem in that it cannot generate an accurate pulse train corresponding to the actual speed.

In light of the above, an object of the present invention is to provide a fast-forward speed control device that can control the fast-forward speed of a tape by generating a pulse train according to the fast-forward speed of the tape without using a tape contact type pulse generator. .

<Means for Solving the Problems> FIG. 1 is a block diagram showing an embodiment of a rapid traverse speed control device when the present invention is applied to an R-DAT device.

11 is a reading identification unit, 12 is an envelope detector, 13 is an actual speed pulse generation circuit, 14 is a command speed pulse generation circuit, and 15 is a tape feed speed control unit, which includes a selection circuit 15a and a digital speed control unit 15b. have.

16 is a motor drive circuit, and 17 is a reel motor that rotates the reel.

<Operation> A rotating head type magnetic recording/reproducing device performs azimuth recording. Therefore, when a head scans across a track by fast forwarding or rewinding, the playback signal will be large for tracks recorded by the scanning head, and small for tracks recorded by a head other than the scanning head. Become.

Therefore, while the head is reading data from the tape, the envelope waveform signal EVS output from the envelope detector 12 can be sliced at a predetermined level in the actual speed pulse generation circuit 13 to generate a pulse train PS corresponding to the actual speed. can.

However, if the head is not reading data from the tape, the envelope waveform signal cannot be used.

Therefore, during that time, assuming that the motor is rotating at the commanded speed, a pulse train PC corresponding to the commanded speed output from the commanded speed pulse generation circuit 14 is inputted to the digital speed control section 15a to perform speed control.

<Embodiment> FIG. 1 is a block diagram showing an embodiment of a rapid traverse speed control device when the present invention is applied to an R-DAT device, and FIG. 2 is a waveform diagram of each part.

Reference numeral 11 denotes a read-in-progress discrimination unit for discriminating between a period when the head is reading a signal from the magnetic tape and a period when the head is not reading a signal. The read-in-progress discrimination unit 11 is, for example, a magnetic piece 32a, 32b attached to a rotor 31 which rotates together with the heads HD1, HD2 as shown in FIG.
A magnetic sensor (pickup coil, Hall element, etc.) 33 is disposed so as to face the magnet pieces 32a, 32b at a predetermined distance, and further the rotating body 31 is magnetized at a predetermined distance (= a°), and a magnetic sensor 35 is disposed so as to face the magnetization 34 at a predetermined distance.
The magnet piece 32a is aligned in the direction of rotation of the first head.
The magnet piece 32b is similarly arranged at the same position as the second head HD2 in the rotational direction. The magnetic sensor 33 is connected to the magnet pieces 32a,
32b are arranged so as to be able to detect when they reach the reading start position.

Therefore, when the first and second heads HD1 and HD2 each reach a position where they can read data from the magnetic tape MT, a signal is generated from the magnetic sensor 33 and a high level signal is generated, which then corresponds to a 90° rotation. If the signal is set to low level when several pulses are generated from the magnetic sensor 35, this signal becomes the reading signal RDI (see FIG. 2).

Returning to FIG. 1, 12 is an envelope detector that generates an envelope waveform signal EVS having the envelope of the head reproduction signal RS (see FIG. 4). A rotating head type magnetic recording/reproducing device performs azimuth recording, so when the first head HD1 scans across each track, the tracks recorded by the second head HD2, which is separate from the first head, are scanned. The voltage of the reproduced signal is significantly lower than that of the reproduced signal from the track recorded by the head HD1. Therefore, the envelope waveform of the reproduced signal RS becomes larger or smaller for each track.

13 is a pulse train PS according to the actual speed by slicing the envelope waveform signal EVS at a predetermined level VS.
14 is a command speed pulse generation circuit that generates a pulse train PC with a frequency corresponding to the command speed.

Reference numeral 15 denotes a tape feed speed control section, which includes a selection circuit 15a and a digital speed control section 15b. The selection circuit 15a is reading (RDI="1")
In this case, the actual speed pulse PS from the actual speed pulse generation circuit 13 is selectively output, and when reading is not in progress (RDI="0"), the command speed pulse train PC output from the command speed pulse generation circuit 14 is selectively output.
Further, the digital speed control section 15b receives command speed data.
Pulse width modulation is performed using the pulse train inputted through the CMD and the selection circuit to generate a speed error signal V _E having a duty (pulse width) corresponding to the speed difference between the actual speed and the commanded speed. Note that if the actual speed and command speed match, the duty of the speed error signal will be 50%. Since the digital speed control section is well known, a detailed explanation thereof will be omitted, but please refer to, for example, ``Digitization of VTR servo circuits and its optimal design method'' (Japan Industrial Technology Center).

16 is a motor drive circuit, and 17 is a reel motor that rotates the reel.

According to the embodiment shown in FIG. 1, when one of the first and second heads is reading data from the magnetic tape (read signal RDI="1"), the actual speed pulse train PS corresponding to the actual speed is the selection circuit 15a
is input to the digital speed control section 15b via
The digital speed control section 15b inputs a speed error signal V _E having a pulse width corresponding to the speed difference between the commanded speed and the actual speed to the motor drive circuit 16 to drive the reel motor 17 so that the tape fast forward speed changes to the commanded speed. Control so that

If neither the first nor the second head is reading data from the magnetic tape (reading signal RDI="0"), the command speed pulse train PC having a frequency corresponding to the command speed is selected by the selection circuit 15a. The signal is input to the digital speed control section 15b via the digital speed control section 15b, and the digital speed control section outputs a speed error signal V _E having a pulse width of 50% duty. That is, when RDI="1", closed-loop speed control is performed, and when RDI="0", open-loop speed control is performed.

Fig. 5 is a block diagram of another embodiment of the present invention;
The figure is a waveform diagram of each part, and the same parts in FIG. 5 as in FIG. 1 are given the same reference numerals.

The differences from the embodiment shown in FIG. 1 are as follows: (a) The selection circuit 15a is replaced by a digital speed control section 15b.
(b) The pulse train PC output from the command speed pulse generation circuit 14 is a pulse train with a duty of 50%. (c) Only the actual speed pulse train is input to the digital speed control section 15b. (d) The selection circuit 15a includes the digital speed control section 15b.
The speed error pulse train V _E ′ and the command speed pulse train PC are input, and the reading signal DI is “1”, “0”.
A predetermined signal is selectively output as the speed error signal _VE in accordance with the speed error signal VE.

According to the embodiment of FIG. 5, the reading signal RDI
Regardless of the actual speed pulse generation circuit 13, the actual speed pulse train PS (see FIG. 6) is input to the digital speed control section 15b, and the digital speed control section 15b receives the command speed data CMD and the input pulse train. is used to generate a speed error pulse train V _E ' having a pulse width corresponding to the speed difference between the actual speed and the command speed. Note that when data is not being read (RDI = "0"), there is no pulse in the actual speed pulse train PS (actual speed = zero), so the speed error pulse V _E ' is at a high level during that time. There is.

Now, when either the first or second head reads data from the magnetic tape (RDI="1"), the selection circuit 15a outputs the speed error pulse train V _E ' as the speed error signal V _E to the motor drive circuit 16. When neither the first nor the second head is reading data from the magnetic tape (reading signal RDI = "0"), the duty is 50% and the frequency corresponds to the command speed. Command speed pulse train
Motor drive circuit 16 using PC as speed error signal V _E
Output to.

In other words, as in Fig. 1, when RDI="1", closed-loop speed control is performed, and RDI="1".
In the case of 0'', open-loop speed control will be performed.

Although the case where a digital speed control section is used has been described above, the present invention is not limited to such a case.

<Effects of the invention> According to the invention, during data reading, the pulse train obtained by slicing the envelope waveform signal having the envelope of the reproduced signal is used as the actual speed pulse train to perform closed-loop speed control. If not, the speed is controlled in an open loop using a command pulse train with a frequency and duty corresponding to the command speed, so it is possible to adjust the tape fast-forward speed without using a tape contact type pulse generator. It became possible to control the fast forwarding speed of the tape by generating a corresponding pulse train.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of a rapid traverse speed control device when the present invention is applied to an R-DAT device, Fig. 2 is a waveform diagram of each part of Fig. 1, and Fig. 3 is a diagram of the identification section during reading. 4 is a waveform diagram showing the principle of actual speed pulse generation, FIG. 5 is a block diagram of the second embodiment of the present invention, FIG. 6 is a waveform diagram of each part of FIG. 5, and FIGS. FIG. 8 is a schematic explanatory diagram of the R-DAT device. 11...Reading identification unit, 12...Envelope detector, 13...Actual speed pulse generation circuit, 1
4... Command speed pulse generation circuit, 15... Tape feed speed control section, 15a... Selection circuit, 15b...
...Digital speed control unit, 16...Motor drive circuit, 17...Reel motor.

Claims (1)

[Claims for Utility Model Registration] (1) Recording signals on the magnetic tape or reading signals from the magnetic tape by feeding the magnetic tape in the longitudinal direction of the tape and rotating the head at an angle with respect to the longitudinal direction of the tape. A fast-forwarding speed control device for a reproduction audio device includes a reading identification section that identifies a period when a head is reading a signal from a magnetic tape and a period when it is not reading a signal, and an envelope waveform signal having an envelope of a head reproduction signal. An envelope detector, an actual speed pulse generation circuit that slices the envelope waveform signal at a predetermined level and generates a pulse train according to the actual speed, a command speed pulse generation circuit that generates a pulse train according to the command speed, and a magnetic head. A tape that generates a speed error signal using the actual speed pulse train while the head is reading a signal from the tape, and generates a speed error signal using the command speed pulse train when the head is not reading a signal from the magnetic tape. 1. A rapid feed speed control device comprising a feed speed control section. (2) The fast-forward speed control device includes: a selection circuit that selects and outputs one of the actual speed pulse train and the command pulse train based on the signal from the reading identification unit; Utility model registration claim No. (1) characterized by having a digital speed control section that generates a speed error signal having a pulse width according to the speed difference between the commanded speed and the actual speed.
The rapid traverse speed control device described in Section 3. (3) The rapid traverse speed control device performs pulse width modulation according to the speed difference between the actual speed and the command speed using the command speed data and a pulse train corresponding to the actual speed output from the actual speed pulse generation circuit. A digital speed control section that generates a speed error signal, a speed error signal output from a pulse width modulation circuit based on a signal from a reading identification section, and a duty 50 output from a command speed pulse generation circuit.
Utility model registration claim No. (1) characterized by having a selection circuit that selectively outputs one of the pulse trains of %.
The rapid traverse speed control device described in Section 3.