KR910003016B1 - Control circuit for reel motor - Google Patents

Abstract

Controller senses signals from the head when high speed searching, which results in controlling the speed of the reel motor. Envelope signal (S2) from the head (1) is changed into square wave (S3) through Schmit Trigger (4) and the square wave is transduced into corresponding voltage signal at F/V converter (5). Differential amplifier (8) compares the voltage signal outg of (5) with reference voltage signal from (7) and produces driving signals to match the speed of the headdrum (14) with running speed of the magnetic tape (2). And then precision controller (11), composed of DSP IC, is able to control drum motor driver (13) accurately, tracing the sound signal track.

Description

DAT reel motor controller

1 is a configuration diagram of a control device according to the present invention.

2A to 2C are output waveform diagrams of the circuit portions of FIG.

* Explanation of symbols for main parts of the drawings

1 head 2 magnetic tape

3: low pass filter 4: Schmidt trigger

5, 7: F / V converter 6: Frequency generator

8: differential amplifier 9: fixed signal generator

10: reel motor drive circuit 11: precision control circuit

12: mode selection switch 12: drum motor drive circuit

14: head drum 15: reel motor

The present invention relates to a circuit device for controlling a reel motor of a DAT, and more particularly, to a reel motor controller of a DAT capable of controlling the speed of a reel motor by using a signal detected from a head during a high speed driving. It is about.

[Traditional Technology and Problems]

In general, the DAT (Digital Audio Taperecorder) system is capable of recording or reproducing a voice signal while the head on the head drum is connected to the magnetic tape, where the operation such as during high-speed search, high-speed driving and high-speed rewinding can be performed. In this case, the magnetic tape must be driven at a speed of 150 to 200 times that of normal recording and reproducing, so the reel motor speed must be controlled to a predetermined rotational speed. That is, in order to increase the relative connection speed with the head, the audio signal is recorded while the magnetic tape is inclined at a certain angle, and the head on the drum tracks the voice signal track inclined at a certain angle on the magnetic tape while the voice signal is recorded. In the case of high-speed search, the speed of the magnetic tape is relatively high. Therefore, if the head rotates at the speed of normal driving, the voice signal track of the tape cannot be accurately tracked. The rotational speed of the head should also be changed to correspond with the speed of the magnetic tape. However, it is very difficult to shift the speed of the head drum motor linearly, and it also adversely affects the motor. Therefore, the rotational speed of the motor is shifted only in two ways. Since the running speed of the tape, that is, the rotational speed of the reel motor, cannot be increased to the required speed instantaneously, it has to be accelerated linearly. Therefore, the speed of the reel motor can be accelerated quickly to change the head drum motor. The speed should correspond to the speed, and the driving speed of the tape should be controlled so that the head can accurately track the audio signal track of the magnetic tape.

Meanwhile, in order to control the speed of the reel motor as described above, a method of controlling the speed of the reel motor by generating a frequency proportional to the rotational speed of the reel motor and applying it to the control device is adopted. Since the speed of the tape is variable according to the thickness of the tape wound on the reel, the relative speed with the head changes, so the head accurately tracks the audio signal track of the tape during high-speed driving and high-speed search. There was a problem that you can not.

In addition, instead of using a fixed servo control system to precisely control the reel motor corresponding to the rotational speed of the head drum, there is also a method of performing optimal control by using a microcomputer to achieve the most suitable driving state. Since the price of the peripheral device is very expensive, there was a problem that the unit price of the product increases significantly, especially during mass production.

[Purpose of invention]

The present invention has been invented in view of the above, by converting the signal detected from the magnetic tape into a square wave and converting it into a voltage signal, and comparing the converted voltage signal with the voltage generated from the reference frequency signal, The output of the DAT reel motor control device enables the head to accurately track the voice signal track even during high-speed search by controlling the rotation speed of the reel motor while maintaining the speed stably. The purpose is.

[Configuration of Invention]

The present invention for achieving the above object is a low pass filter (3) for removing the high frequency components from the read signal (S1) detected by the magnetic tape (2) head 1, and the low pass filter (3) Schmitt trigger (4) for generating a square wave (S3) from the envelope signal (S2) passing through the), F / V converter (5) for generating a voltage signal corresponding to the frequency based on the square wave (S3) A frequency generator 6 for generating a reference frequency for high-speed driving, an F / V converter 7 for generating a voltage signal corresponding to the frequency from the reference frequency, and the F / V converters 5 and 7 A differential amplifier 8 for comparing the outputs and amplifying the difference between the output values and a fixed signal generator 9 for generating a reel motor fixed signal when the output of the differential amplifier 8 reaches a predetermined value. Supplying control signals to the reel motor driving circuit 10 and the precision control circuit 11 It is structured to give.

Here, reference numeral 12 denotes a mode selection switch, 13 a drum motor driving circuit, 14 a head drum, and 15 a reel motor.

[Action]

The control device according to the present invention configured as described above converts the envelope signal detected from the head into a square wave, and then outputs a voltage signal corresponding to the frequency and compares it with a reference frequency at the time of high-speed search to amplify and output the difference. The reel motor's rotational speed can be controlled so that the head can accurately track the audio signal track of the magnetic tape even during high-speed driving and high-speed search, so that the head can detect the tape from the tape without using expensive parts such as a microcomputer. Based on the signal, it is possible to directly control the rotation speed of the reel motor.

EXAMPLE

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a configuration diagram of the reel motor control apparatus of the DAT according to the present invention. In the mode selection switch 12, the constant speed driving (PL), high speed search (HS), and precision control (SC) mode terminals are respectively selected. The drum motor driving circuit 13 according to the selected mode signal drives the head drum 14 so that the head 1 detects the predetermined signal S1 from the magnetic tape 2. In addition, the frequency generator 6 for generating a reference frequency for high-speed search is to generate the respective reference frequency selectively for the fast forward (FF) and rewind (REW) mode, the present invention The operation of the circuit device according to the present invention will be described in detail.

First, when the mode selection switch 12 is selected as the constant speed driving (PL) mode, the head 1 and the magnetic tape 2 run at a normal speed, and the head 1 stops the audio signal track of the magnetic tape 2. Accurately track and read the information recorded on the magnetic tape 2. At this time, if the user selects the high speed search mode, the mode selection switch 12 switches from the constant speed driving (PL) mode to the high speed search (HS) mode, and the drum motor driving circuit 13 receives the drum motion when the high speed search signal is input. By accelerating the rotor, the head drum 14 is rotated at a high speed, so that the head 1 tracks the audio signal track of the magnetic tape 2 at high speed. Since the magnetic tape 2 is in a constant speed driving state which has not yet been accelerated, the traveling speed of the magnetic tape 2 is relatively slow with respect to the head 1, so that the head 1 stops the audio signal track of the magnetic tape 2. Tracking is made while traversing, whereby the head 1 detects the signal S1 as shown in FIG. 2A and outputs it to the low pass filter 3. At this time, for example, when the traveling speed of the magnetic tape 2 is lower than the rotational speed of the head drum 14, a signal S1 having a low frequency is generated, and conversely, the traveling speed of the magnetic tape 2 is set to the head drum 14. If it is faster than the rotation speed, a high frequency signal S1 is generated.

Next, this signal S1 is removed from the low pass filter 3 and the high frequency component is removed and output as an envelope signal S2 as shown in (b) of FIG. 2, and this signal S2 is again used to generate the Schmitt trigger 4. Through the square wave (S3) having the same frequency through the converted square wave signal (S3) is converted into a voltage signal corresponding to the frequency through the F / V converter (5), then one side of the differential amplifier (8) Is applied to the input terminal A.

On the other hand, the frequency generator 6 generates a proper frequency of the signal S1 generated when the head 1 tracks the magnetic tape 2 in the high-speed search (HS) mode, and from the frequency generator 6 Since the proper frequency of is different in the fast-forward (FF) and rewind (REW) modes, each reference frequency is generated for each mode, and the respective reference frequency signal F / V converter 7 for each mode is used. Is converted into a voltage signal and then applied to the other input terminal (B) of the differential amplifier (8).

Next, the differential amplifier 8 compares the output of the detection signal (signal input to terminal A) and the reference signal (signal input to terminal B) applied to both input terminals and amplifies the difference. If the frequency difference between the signal and the reference signal is large, the voltage difference is also large, and the output from the differential amplifier 8 becomes large. In addition, when the detection signal is sufficiently close to the reference signal, the voltage difference is small, so that the output of the differential amplifier 8 also becomes small. At this time, a variable resistor (VR) and a resistor (R1) fed back from the output stage are provided at one input terminal of the differential amplifier (8) so that the value output to the output stage of the differential amplifier (8) can be set to a predetermined value. .

The output signal from the differential amplifier 8 is output to the reel motor driver circuit 10 and the fixed signal generator 9, wherein the reel motor driver circuit 10 is output from the differential amplifier 8; The driving speed of the magnetic tape 2 is accelerated by driving control of the reel motor 15 based on the output signal. That is, when the traveling speed of the magnetic tape 2 is slower than the rotational speed of the head drum 14 as in the initial stage of the high-speed search operation, a reel motor 15 is output because a high level voltage signal is output from the differential amplifier 8. Will increase the rotation speed.

On the other hand, the fixed signal generator 9 determines a matching relationship between the rotational speed of the head drum 14 and the traveling speed of the magnetic tape 2 on the basis of the output signal from the differential amplifier 8 and accordingly output signal accordingly. [In this embodiment, when matching is made, the "H" level) is outputted to the precision control circuit 11.

In other words, the fixed signal generator 9 is composed of comparators Amp1 and Amp2 to which reference voltages of Vref1 and Vref2 are applied to the inverting terminal (−), as shown in FIG. Here, Vref1 and Vref2 are experimental voltage values corresponding to the upper limit value and the lower limit value of the optimum driving speed range of the magnetic tape 2, respectively.

That is, Vref1 = Vcc · (R3 + r4) / (R2 + R3 + R4)

Vref2 = Vcc · R4 / (R2 + R3 + R4). (Vref1〉 Vref2)

Therefore, when the running speed of the tape is slower than the rotational speed of the head drum 14, that is, when Vin &lt; Vref2, the output of the comparator Amp1 becomes " L " level so that the comparator Amp2 is enabled and Since the output of Amp2 is at the "L" level, the "L" level is output from the fixed signal generator 9, and the traveling speed of the tape is within a predetermined range which is set. When Vref2 <Vin <Vref1, the comparator (Amp2) The output of the comparator Amp2 becomes the "L" level and the output of the comparator Amp2 becomes the "H" level, so that the "H" level is output from the fixed signal generator 49. On the other hand, when the driving speed of the tape 2 is faster than the rotational speed of the head drum 14 and Vin &gt; Vref1, the output of the comparator Amp1 becomes the &quot; H &quot; level so that the comparator Amp2 is disabled and the fixed signal generator From "9", the "L" level is output.

Next, the precision control circuit 11 determines whether the running speed of the head drum 14 and the tape 2 is matched based on the output signal from the fixed signal generator 9, and executes a predetermined process accordingly. do.

That is, the precision control circuit 11 is composed of a conventional DSP IC (Digital Signal Processing IC), which is output when the signal of the "H" level from the fixed signal generator 9 (head drum 14 and When the traveling speed of the magnetic tape 2 is matched], the mode selection switch 12 described above is controlled to switch the connection terminal with the drum motor drive circuit 13 from the HS terminal to the SC terminal, and Although not, the phase of the signal input from the head and the signal from the VCO circuit provided therein is compared, and this is input to the SC terminal of the mode selection switch 12 as a tracking signal.

Therefore, in this case, the drum motor driving circuit 13 accurately tracks the voice signal track by precisely controlling the rotation speed of the head drum 14 according to the tracking signal.

As described above, according to the present invention, in the high-speed search mode, the reel motor driving circuit 10 drives and controls the reel motor in accordance with the output signal from the differential amplifier 8 so that the rotation speed of the head drum 14 After the matching of the traveling speed of the magnetic tape 2 and the matching is made, the precision control circuit 11 precisely controls the drum motor driving circuit 13 so that the voice signal track can be accurately tracked.

[Effects of the Invention]

As described above, according to the present invention, the envelope signal detected from the head is converted into a square wave, and then a voltage signal corresponding to the frequency is output and compared with a reference frequency in high-speed search to amplify and output the difference. It is possible to control the rotation speed of the rotor, and the head can accurately track the audio signal track of the magnetic tape even during high-speed driving and high-speed search, so the envelope detected from the tape by the head without using expensive parts such as microcomputer Based on the signal, it is possible to directly control the rotation speed of the reel motor.

Claims (4)

In the reel motor control apparatus used for the DAT, a low pass filter (3) for removing high frequency components from the read signal (S1) detected by the magnetic tape (2) by the head (1), and the low pass filter. Schmitt trigger (4) for generating a square wave (S3) from the envelope signal (S2) passed through (3), F / V converter for generating a voltage signal corresponding to the frequency based on the square wave (S3) ( 5), a frequency generator 6 for generating a reference frequency in high-speed driving, an F / V converter 7 for generating a voltage signal corresponding to the frequency from the reference frequency, and the F / V converters 5 and 7 A differential amplifier 8 that compares the output of the amplifier and amplifies the difference, and a fixed signal generator 9 that generates a reel motor fixed signal when the output of the differential amplifier 8 reaches a predetermined value. The control signal is supplied to the reel motor driving circuit 10 and the precision control circuit 11. For DAT, it characterized in that to give the reel Motor control device. 2. The reel motor control of the DAT according to claim 1, wherein the frequency generator 6 is capable of selectively generating respective reference frequencies according to the mode selection of fast forward (FF) and rewind (REW). Device. According to claim 1, wherein the head (1) is installed in the head drum 14 is rotated by the drum motor driving circuit 13, the drum motor driving circuit has a constant speed (PL) and high-speed search ( A reel motor control device for a DAT, characterized in that a mode selector switch (12) for selecting an HS) and a precision control (SC) mode is connected. 2. The reel motor control apparatus according to claim 1, wherein the differential amplifier (8) is provided with a gain adjusting feedback resistor (VR) between one input terminal and one output terminal.

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