JPH04163758A - Cylinder controller for magnetic recording/reproducing apparatus - Google Patents

Abstract

PURPOSE:To achieve a higher speed in drawing of phase by detecting a phase error of a rotary cylinder with respect to a rotation reference signal with the counting of a speed detection signal to be outputted from a frequency generator FG to perform a phase control detecting the current phase error. CONSTITUTION:In obtaining of a phase error of a rotary cylinder 3 with respect to a rotation reference signal at the start of a phase control of the rotary cylinder 3, not only a phase detection signal is used as outputted from a phase signal generator (PG)10 but also a speed detection signal outputted from an FG5 is counted and the resulting phase difference is detected with a first phase difference detection circuit 13 and a second phase difference detection circuit 17 to perform a phase control. As a result, the phase error can be fed back to a control system at a shorter cycle as compared with the phase detection signal thereby allowing the drawing of a phase quickly. This also enables addressing to even altering of the rotational speed of the rotary cylinder 3 simply by changing a software without the addition and changing of a hardware.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic recording and reproducing apparatus for recording and reproducing information on a magnetic tape using a rotating head, which can be used in video tape recorders (VTRs), digital audio recorders (DATs), etc. The present invention relates to a cylinder control device.

2. Description of the Related Art In recent years, recording and reproducing apparatuses for recording and reproducing information on a magnetic tape (recording medium) using a rotating head such as a VTR or DAT have been put into practical use.

Hereinafter, a conventional cylinder control device for a magnetic recording/reproducing device will be explained with reference to the drawings.

FIG. 6 is a block diagram of a cylinder control device of a conventional magnetic recording/reproducing apparatus, and FIG. 7 is a waveform diagram of main parts in a phase detection signal waveform shaping circuit and a delayed pulse output circuit. Figure 6,
In FIG. 7, 1 is a magnetic tape, 2a and 2b are heads for recording and reproducing, and 3 is a recording and reproducing head 2 symmetrically about the rotation axis.
4 is a magnetic tape drive circuit that stably drives the magnetic tape 1 at a variable speed; 5 is a rotating cylinder that outputs a signal with a frequency proportional to the rotational speed of the rotating cylinder 3; (frequency generator), 6 is a first waveform shaping circuit that shapes the output signal of PG5 into a rectangular wave, 7 is a first waveform shaping circuit that rotates the period of the output signal of 6 by counting the internal clock. a speed detection circuit that outputs the speed of the cylinder 3 as a digital value, a subtractor 9 that calculates the difference between the speed target value V corresponding to the set target rotation speed of the rotating cylinder 3 and the output value of the speed detection circuit 7; 1
0 is the head 2 al when the rotating cylinder 3 rotates.
2 signal once per rotation with always the same phase difference with respect to b (7th
11 is a second waveform shaping circuit that shapes the output signal of the PGIO into a rectangular wave (see FIG. 7G) using a Schmitt comparator or the like. 12 is a delayed pulse output circuit that outputs the output signal of the second waveform shaping circuit 11 as a pulse (see the seventh diagram) with a pulse width (To) determined by a delay time set from the outside using a monostable multivibrator or the like. By adjusting this pulse width, the phase during reproduction of the head 2a is accurately defined. That is, the positional deviation between the output signal of PGlo and the head 2a is adjusted by this pulse width,
The mounting of the head 2a absorbs positional variations. 13 is a phase difference detection circuit that counts the phase difference between the output of the delayed pulse output circuit 12 and the rotation reference signal 26 using an internal clock and outputs it as a digital value; A subtracter that takes the difference from the output, 22 is a subtracter 9
23 is a digital filter that filters the output data of the adder 22 and has integral filter characteristics to improve the control characteristics in the low frequency range. 24 is a digital filter. A D/A conversion circuit 25 converts the output data of the filter 23 into an analog voltage.
This is a cylinder drive circuit that drives the rotary cylinder 3 based on the output of the A conversion circuit 24.

The operation of the cylinder control device for the magnetic recording/reproducing apparatus configured as described above will be described below.

In FIG. 6, FG5. a first waveform shaping circuit 6;
Speed detection circuit 7. Subtractor 9. Digital filter 23. D
/A conversion circuit 24. In the speed control loop formed by the cylinder drive circuit 25, the output frequency of the FG 5 becomes a value corresponding to the speed target value V, and the rotating cylinder 3 stably rotates at a substantially constant rotation.

Furthermore, in the phase control loop of PGIO, second waveform shaping circuit 11° delayed pulse output circuit 129 phase difference detection circuit 13° subtracter 15, the output signal of PGlo is first shaped into a rectangular wave by the waveform shaping circuit 11. Then, the delayed pulse output circuit 12 outputs a pulse having a pulse width of a delay time TO corresponding to the positional deviation with respect to the head 2a, in response to the output signal of the second waveform shaping circuit 11. Next, the phase difference detection circuit 13 determines the phase difference between the pulse and the rotation reference signal 26, the subtracter 15 calculates the difference between the phase difference and the target phase difference value T1, and the output data, that is, the phase difference By controlling ΔT to be zero, the head 2a rotates while maintaining a predetermined phase T1 with respect to the rotation reference signal 26.

Problems to be Solved by the Invention However, in the conventional cylinder control device of the magnetic recording and reproducing device described above, phase control is performed by adding the phase difference between the phase detection signal from the PGIO and the rotation reference signal 26 as data for the cylinder drive circuit 25. Therefore, there is a problem that it is slow for the rotating cylinder 3 to synchronize the phase with the rotation reference signal 26 (this is called phase pull-in) at the time of starting the phase control, especially for rotations with a large moment of inertia. This was noticeable in the cylinder.

The present invention has been made to solve the above-mentioned conventional problems, and it is an object of the present invention to provide a cylinder control device for a magnetic recording/reproducing device that has a simple configuration and can quickly pull in a phase when starting phase control.

Means for Solving the Problems To achieve this object, a cylinder control device for a magnetic recording and reproducing apparatus according to the present invention includes a rotating cylinder to which a recording and reproducing head is attached, and a magnetic tape drive means for running a magnetic tape at a variable speed. and a first waveform shaping means for shaping a speed detection signal generated from the rotary cylinder multiple times per rotation into a rectangular wave and outputting the waveform, and an output signal of the first waveform shaping means being externally settable. delay pulse output means for adding and outputting a delay time; speed detection means for outputting a digital value corresponding to the rotational speed of the rotary cylinder from the period or frequency of the output signal of the delay pulse output means;
speed error calculation means for outputting a difference between the output value of the speed detection means and a value corresponding to a target cylinder rotation speed as a digital value; and a phase detection signal generated once per rotation from the rotating cylinder in a rectangular shape The second waveform is shaped into a wave and output.
a first phase difference calculation means for outputting a phase difference between the rotation reference signal and the phase detection signal as a digital value; a first phase difference target value output means for outputting a target value of the phase difference with the phase detection signal as a digital value; and an output value of the first phase difference target value output means and the first phase difference target value output means.
a first phase difference error detection means for outputting the difference between the output of the phase difference detection means and the output of the phase difference detection means as a digital value; a counter that is reset by the phase detection signal and counts the rotational speed detection signal; second phase difference target value output means for outputting a target value of the phase difference between the rotation speed detection signal and the rotation reference signal as a digital value each time the rotation speed detection signal reaches a predetermined value; a second phase difference detection means for detecting a phase difference between the rotation speed detection signal and the rotation reference signal and outputting it as a digital value; and an output of the second phase difference target value output means and the second phase difference. second phase difference error detection means for outputting a difference with the output of the detection means as a digital value;
switching means for selecting and outputting the output of the first phase difference error detection means or the second phase difference error detection means;
Adding means for adding the output of the switching means and the speed error calculating means; a digital filter for digitally filtering the output of the adding means; and a D/A conversion circuit for converting the output of the digital filter into an analog electrical signal. and cylinder drive means for rotating the rotary cylinder using the output of the D/A conversion circuit as a drive signal.

With the above-described configuration, the present invention detects the phase error of the rotating cylinder with respect to the rotation reference signal not only by the phase detection signal output from the PG but also by the F when phase control of the rotating cylinder is started.
Since the speed detection signals output from the can be drawn in.

Embodiment FIG. 1 is a block diagram of a cylinder control device for a magnetic recording/reproducing apparatus in an embodiment of the present invention, and FIG. 2 is a block diagram.

3 is an operational waveform diagram, FIG. 4 is a block diagram showing an example of the configuration of the speed detection circuit of FIG. 1, and FIG. 5 is a block diagram of an example of the configuration of the phase difference detection circuit of FIG. 1.

In Figures 1 to 3, 1 is a magnetic tape, 2al
2b is a recording/reproducing head, 3 is a rotating cylinder, 4 is a magnetic tape drive means, 5 is FGl, 6 is a first waveform shaping circuit,
7 is speed detector, 9.15 is subtractor, 10 is PG, 11
12 is a second waveform shaping circuit, 12 is a delayed pulse output circuit, and 1 is a second waveform shaping circuit.
8 is an adder, 23 is a digital filter, 24 is a D/A conversion circuit, and 25 is a cylinder drive circuit, which are the same components as in the conventional example. 8 is a speed target value output circuit that generates data corresponding to the target rotation speed of the rotary cylinder 3; 14 is a speed target value output circuit that corresponds to the target rotation speed of the rotary cylinder 3;
a first phase difference target value output circuit that outputs a target value of the phase difference between the rotation reference signal 26 (see FIG. 2A) and the output signal of the delayed pulse output circuit 12 (see FIG. 2A) as a digital value;
16 is a counter that is reset at the fall of the output signal of the delayed pulse output circuit 12 and outputs a pulse every time the output signal of the first waveform shaping circuit 6 is counted a predetermined number; 17 is a counter that outputs a pulse at a predetermined time after the counter 16 is reset; 18 is an adder that adds the output of the first phase difference detection circuit 13 and the output of the second phase detection circuit 17, and 19 is a counter. 16, outputs a target phase difference from the rising edge of the rotation reference signal 26 until the counter 16 reaches a predetermined value.
20 is a subtracter that takes the difference between the output data of the second phase difference target value output circuit 18 and the output data of the adder 18; 21 is a subtracter 15 based on the value of the counter 16; This is a changeover switch that switches between the output of the subtracter 20 and the output of the subtracter 20.

FIG. 2A shows a waveform diagram of the rotation reference signal 26, in which both H and L are rectangular waves with a period T1. The rotation reference signal 26 is a reference signal during recording and reproduction, and the period T1 is a half period of the rotation of the rotary cylinder. Figure 2A shows a waveform diagram of the signal after waveform shaping of the PGIO output signal (hereinafter referred to as PG multiplied signal), and T11 represents the phase difference from the rising edge of the rotation reference signal 26 to the falling edge of the PG multiplied signal. ΔT1 indicates the error between the phase difference and the target phase difference value. FIG. 2 shows the output signal waveform diagram of the counter 16, and A is the output signal waveform diagram of the counter 16.
ΔTOI indicates the time from the falling edge of the PG double signal until the counter 16 is reset, and ΔTOI indicates the reset position of T2. T3°T4 indicates the target phase difference time from the rising edge of the rotation reference signal 26 for each output pulse of the counter 16, and T12. T13. T14 indicates the time from when the counter 16 is reset to the output pulse, and ΔT2. ΔT3. AT4 indicates the error between the target phase difference value and the actual phase difference for each output pulse of the counter 16.

FIG. 3 shows the timing relationship of the PG multiplied signal and the FG multiplied signal, and shows that there is a time difference of ΔTOI between the reset position of the counter 16 and the falling edge of the PG multiplied signal.

In FIG. 4, 101 is a clock generator, lO2 is a counter that counts the output of the clock generator 102, and 103
104 is a delay circuit, 104 is a latch circuit, and latch circuit 1
04 latches the count data of the counter 102 at the rising edge of the FG multiplication signal. Further, the counter 102 is cleared immediately after the data is latched into the latch circuit 104 via the delay circuit 103. Therefore, the latch circuit 104 holds the number of clock pulses generated by the clock generator 101 during one signal period of the FG signal, and
Counts the double signal period as a digital value and outputs it.

In FIG. 5, to explain the case of the first phase difference detection circuit 13, 201 is a clock generator, 202 is a counter that is cleared at the rising edge of the rotation reference signal 26 and counts the output of the clock generator 201, and 203 is a counter that counts the output of the clock generator 201. This is a latch circuit that latches the count data of the counter 202 at the falling edge of the PG double signal. The number of clock pulses is held and output. Next, to explain the case of the second phase difference detection circuit 17, the counter 202 is cleared at the same timing as the counter 16 is cleared, the output of the clock generator 201 is counted, and the latch circuit 203 is The count data of the counter 202 is latched at the rising edge of , and the latch circuit 203 holds the time from when the counter 16 is cleared until the pulse is output as the number of clock pulses generated by the clock generator 201.
Output.

The operation of the cylinder control Mfll of the magnetic recording/reproducing apparatus of this embodiment configured as described above will be explained below.

In FIG. 1, FG5. a first waveform shaping circuit 6;
Speed detection circuit 7. Speed target value output circuit 8. Subtractor 9. Digital filter 23. In the speed control loop consisting of the D/A conversion circuit 24 and the cylinder drive circuit 25, the output frequency of the FG 5 becomes a value corresponding to the speed target value ■, and the rotating cylinder 3 stably rotates at a substantially constant rotation.

After the speed control is performed as described above, when starting the phase control loop, first, the output signal of the PG generator 0 is waveform-shaped into a rectangular wave by the second waveform shaping circuit 11, and then the first phase difference detection circuit 13 The phase difference Tll with the rotation reference signal 26 is detected. Next, the subtracter 15 calculates the difference from the target phase difference value T1, that is, the phase difference error ΔT1, and the adder 22 adds the phase difference error ΔT1 to the output data of the subtracter 9 through the changeover switch 21. The counter 16 is cleared at the first rising edge of the FG multiplied signal after the fall of the rotation reference signal 26, and immediately starts counting the FG multiplied signal. Next, the second phase difference detection circuit 17
A time T12 from the time when the counter 16 is cleared to the rising edge of the output pulse generated after counting the signal multiplied by a predetermined number of FG is detected. Next, the adder 18 adds the output data T11 of the first phase difference detection circuit 13 and the output data T12 of the second phase difference detection circuit 17. next,
The subtracter 20 calculates the difference between the output data of the second phase difference target value output circuit 19 and the output data of the second phase difference detection circuit 17 according to the value of the counter 16, that is, ΔT2,
The phase difference error ΔT2 is added to the adder 2 through the changeover switch 21.
2 is added to the output data of the subtracter 9. Similarly, the above process is repeated every time the counter 16 counts a predetermined number of FG multiplied signals and outputs a pulse until the next falling edge of the PG multiplied signal arrives.

Here, if the time difference between the falling edge of the rotation reference signal 26 and the reset of the counter 16 when the rotating cylinder 3 is accurately rotating at the target speed is ΔT, then
Since the time difference ΔT varies depending on the rotary cylinder 3, the counter 1 starts from the rising edge of the rotation reference signal 26.
The target phase difference T until 6 reaches a predetermined value is a value obtained by adding the time difference ΔT. Taking the target phase difference at the first output pulse of the counter 16 as an example, T=T2+ΔT (1). Furthermore, since the measured phase difference TT corresponding to the actual target phase difference T is from the rising edge of the rotation reference signal 26 to the output pulse of the counter 16, TT=T11+ΔT
O1+T12...(2). However, in reality, during phase control, the time difference ΔT and the time difference ΔT01 can be considered to be almost equal due to speed control, and the phase difference error ΔT
2 is expressed as ΔT2=T−TT=72−(Tl 1+T12) (3).

As described above, phase difference errors ΔTl, ΔT2°・
The cylinder 3 is controlled so that . After drawing in the phase, switch 21 is switched to subtracter 15.
By fixing it to the side, the head 2a is stably rotated while maintaining a predetermined phase difference T1 with respect to the rotation reference signal 26.

As described above, according to this embodiment, when the phase control of the rotary cylinder 3 is activated, the phase error of the rotary cylinder 3 with respect to the rotation reference signal 26 is detected not only by the phase difference detection signal output from the PGIO but also by the output from the FG5. The speed detection signal is counted and the phase difference at that time is detected to perform phase control. Therefore, the phase error can be fed back to the control system in a shorter cycle than the phase detection signal, and the phase can be quickly drawn in. .

In addition, in FIG. 1, the part surrounded by the broken line, that is,
Speed detection circuit 7, speed target value output circuit 8, subtracter 9.
15. 20, counter 16, first phase difference detection circuit 1
3. Second phase difference detection circuit 17, first phase difference target value output circuit 14, second phase difference target value output circuit 19, adder 18.22, changeover switch 21, digital filter 23
, the D/A conversion circuit 24 can be configured as one IC,
Furthermore, it can also be configured as a microcomputer.

In particular, the speed detection circuit 7, the speed target value output circuit 8, the subtracter 9. 15. 20, counter 16, first phase difference detection circuit 13, second phase difference detection circuit 17, first phase difference target value output circuit 14, second phase difference target value output circuit 19,
By configuring the adders 18 and 22, the changeover switch 21, and the digital filter 23 as microcomputer software, even when changing the rotational speed of the rotary cylinder 3, the change can be made only by changing the software without adding or changing hardware. be able to.

Effects of the Invention As described above, the present invention detects the phase error of the rotating cylinder with respect to the rotation reference signal at the time of activation of phase control of the rotating cylinder using not only the phase detection signal output from the PG but also the speed detection output from the FG. Since the phase control is performed by counting the signals and detecting the phase difference at that time, the phase error can be fed back to the control system in a cycle shorter than the phase detection signal, and the phase can be quickly drawn in. Furthermore, a speed error detection means, a counter, a first . a second phase difference detection means; a first phase difference detection means; The second phase difference target value output means, switching means, addition means, and digital filter are configured as microcomputer programs, and the counter and D/A conversion circuit are all configured as hardware built into the microcomputer. As a result, it is possible to realize an excellent magnetic recording and reproducing apparatus that can handle changes in the rotational speed of the rotary cylinder only by changing the software without adding or changing hardware.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a cylinder control device of a magnetic recording/reproducing apparatus in an embodiment of the present invention, FIG.
4 is a block diagram showing a configuration example of the speed detection circuit 7 of FIG. 1, and FIG. 5 is a phase difference detection circuit 13.17 of FIG. 1. 6 is a block diagram showing a configuration example of a cylinder control device of a conventional magnetic recording/reproducing apparatus. FIG. 7 is an operation waveform diagram for explaining the operation of the conventional example. 1... Magnetic tape, 2a, 2b... Head, 3
... Rotating cylinder, 4... Magnetic tape drive circuit, 5... FG, 6... First waveform shaping circuit,
7...Speed detection circuit, 9.15.20...
Subtractor, 10...PG, 11...Second waveform shaping circuit, 13...First phase difference detection circuit, 14
...First phase difference target value output circuit, 17... Second phase difference detection circuit, 19... Second phase difference target value output circuit, 18.22... Adder, 23.・・・
Digital filter, 24...D/A conversion circuit, 2
5... Cylinder drive circuit. Name of agent: Patent attorney Akira Okaji and 28 other 2
Figure 3 Figure 4 Figure 5

Claims (2)

[Claims] (1) A cylinder control device for a magnetic recording/reproducing device that performs recording/reproduction by scanning a track formed diagonally on a recording medium with a head attached to a rotating cylinder, which comprises: a rotating cylinder to which the recording/reproducing head is attached; , a magnetic tape drive means for running the recording medium at a variable speed; a first waveform shaping means for shaping a speed detection signal generated from the rotary cylinder multiple times per revolution into a rectangular wave and outputting the waveform; Delayed pulse output means for externally adding and outputting a settable delay time to the output signal of the waveform shaping means of No. 1, and a digital pulse outputting means that corresponds to the rotation speed of the rotary cylinder from the period or frequency of the output signal of the delay pulse output means. speed detection means for outputting a value; speed error calculation means for outputting a difference between the output value of the speed detection means and a value corresponding to a target cylinder rotation speed as a digital value; a second waveform shaping means that shapes the phase detection signal generated twice into a rectangular wave and outputs the waveform, and a first phase difference calculation means that outputs the phase difference between the rotation reference signal and the phase detection signal as a digital value. , a first phase difference target value output means for outputting a target value of a phase difference between the rotation reference signal and the phase detection signal as a digital value according to a target rotation speed of the rotary cylinder; first phase difference error detection means for outputting the difference between the output value of the phase difference target value output means and the output of the first phase difference detection means as a digital value; a counter that counts detection signals; and a second phase difference target value output means that outputs a target value of the phase difference between the rotation speed detection signal and the rotation reference signal as a digital value each time the counter reaches a predetermined value. and a second phase difference detection means for detecting a phase difference between the rotation speed detection signal and the rotation reference signal every time the counter reaches a predetermined value, and outputting the detected phase difference as a digital value; and the second phase difference. a second output unit for outputting the difference between the output of the target value output means and the output of the second phase difference detection means as a digital value;
phase difference error detection means; switching means for selecting and outputting the output of the first phase difference detection means or the second phase difference detection means; and the output of the switching means and the speed error calculation. a digital filter that digitally filters the output of the adding means; a D/A conversion circuit that converts the output of the digital filter into an analog voltage; and the D/A conversion circuit. A cylinder control device for a magnetic recording/reproducing device, comprising: cylinder drive means for rotating the rotary cylinder using the output of the drive signal as a drive signal. (2) The speed error detection means, the counter, the first and second phase difference detection means, the first and second phase difference target value output means, the switching means, the addition means, and the digital filter are configured as microcomputer programs. 2. A cylinder control device for a magnetic recording/reproducing device according to claim 1, wherein the , counter, and D/A conversion circuit are all built into a microcomputer as hardware.