JPS6066678A - Rotating body control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a control device for a rotating body, and particularly to a control device for a rotating body for changing the motor rotation speed in a capstan motor of a magnetic recording/reproducing device (hereinafter referred to as a VTR). It is something.

Conventional Structure and Problems Therein FIG. 1 is a block diagram of a capstan motor control device during VTR playback. In FIG. 1, the magnetic tape 3 is transferred by pressing the capstan shaft 1 and the pinch roller 2, and a frequency generator 5 (hereinafter referred to as FC) is installed in a capstan motor 4 directly connected to the capstan shaft 1.
The signal obtained by the above is inputted to the digital period measuring circuit 7 via the first frequency divider 6, and the output of the digital period measuring circuit 7 is inputted to the first digital-to-analog conversion circuit 8 (hereinafter referred to as a D/mu conversion circuit). ) to obtain a speed system error signal corresponding to the rotation speed of the capstan motor 4. In addition, the control head 9fmlfjL and the roll signal recorded on the magnetic tape 3 are input to the digital phase measuring circuit 11 via the Z component 10 of the output metal 2, and the reference signal from the signal generating circuit 12 is inputted to the digital phase measuring circuit 11. The output of the digital phase measurement circuit 11 is inputted to the second D/A conversion circuit 13 to obtain a phase system error signal of the control signal of the magnetic tape 3 with respect to the reference signal. The speed system and position obtained in this way (・[1 system error signal is input to the mixing circuit 14 to obtain a mixed error signal, and this mixed error signal total compensation circuit 1
After the gain compensation is performed in step 6, the tape speed of the magnetic tape 3 is controlled by manually inputting power to the motor drive circuit 16 and driving the capstan motor 4. In addition to standard playback, which occurs at the same tape feed speed as the tape feed speed, there is a high-speed playback mode that is N times the tape feed speed during recording (N: an integer). In that case, in the capstan motor control device, the first frequency divider 6 divides the frequency of the signal sound from the FGs by N and inputs it to the digital frequency constant circuit 7, and the second frequency divider 10 divides the frequency of the signal sound from the FGs into the magnetic tape. The control 1-roll signal from 3 is divided by N and the digital phase a
++1 constant circuit 11 is inputted to the mixing circuit 14 via the respective error output circuits 1 and 2nd D-A conversion circuits 8 and 13, and the output is outputted to the motor drive circuit 16 via the compensation circuit 16. Then, the capstan motor 4 is driven to transport the magnetic tape at a tape speed that is N times the normal speed. In this case, since the frequency is divided by 2N in the first frequency division F%6, the round transfer function of the speed system becomes as low as 1/N during j1n normal playback, making the tape running unstable. It is necessary to compensate the function. In that case, the compensation circuit 16 shown in FIG. Since the signal is converted into a DC voltage using a low-pass filter, the gain is completely increased in the compensation circuit 16 when fππ is regenerated, so the carrier wave component of the PWM output is also 2111, and the motor drive circuit 16 , there is a phenomenon in which parts of the motor drive σU+ current do not flow, and the controllability of the capstan motor 4 deteriorates, and in the worst case, the position J'l control is not applied, and a noise bar flows on the playback screen. In addition, since the compensation circuit is generally constructed from an analog integrated circuit, there is also the problem that the gain value varies.

OBJECTS OF THE INVENTION The present invention is intended to solve all of these conventional problems, and aims to provide a stable screen even during high-speed playback.

Structure of the Invention The present invention provides a digital period measuring circuit (a digital phase measuring circuit) by inserting a digital gain correction circuit into the output, so that even if the gain is completely changed in accordance with high-speed playback speed, the carrier wave component of the PWM output is An embodiment will be described which provides a control device for a rotating body that can obtain stable reproduced images even during high-speed reproduction by preventing the increase in . FIG. 2 is a block diagram of a capstan motor control device in the VTR playback system 11 of the present invention.

In FIG. 2, the magnetic tape 3 is transferred by pressure bonding between the capstan shaft 1 and the pinch roller 2, and the capstan motor 4VcT'G is driven by the capstan motor 4VcT'G, which is directly connected to the capstan shaft 1.
5! 7 Divide the obtained signal into the 10th frequency by
The digital frequency aa++j constant circuit 7 inputs the digital frequency υJ6111 constant 1 to the digital gain correction circuit 21 of the first digital gain correction circuit 21, and the output of the first digital gain correction circuit 21 The signal is inputted to the D-A conversion circuit 8 of the engine 1 to obtain a speed system error signal corresponding to the rotation speed of the capstan motor 4. 1. The control signal recorded on the magnetic tape 3 is detected by the control head 9,
The output is transferred to the digital position J via the second circuit KN1oi.
il measurement 11]), (from the quasi-signal generating circuit 12, li(/l/4 signal ÷ 3 and phase ratio 11 The output signal of the second digital gain correction circuit 22 is inputted to the shift gain correction circuit 22 to obtain a phase system error signal with respect to the reference signal of the first control signal outputted from the second digital gain correction circuit 22.The speed system and phase system error signals obtained in this manner are input to the total mixing circuit. 14, obtain a mixed error signal, and send this mixed error signal to the motor drive circuit 1.
6 and drives the capstan motor 4 to control the tape speed of the magnetic tape 3.

FIG. 3 shows a main circuit block diagram of the digital gain correction circuit of this embodiment, and FIG. 4 shows all the output waveforms of the PWM circuit 34 in FIG. 3. In FIG. 3, the digital error signal of the digital period measuring circuit 7 (or digital phase measuring circuit 11) is m (m is a positive integer) bit ratio.
The output of the m-bit latch circuit 31 is manually inputted to the notch circuit 31, and the output of the m-bit latch circuit 31 is n(nIdO, ±1.±2.
It is input to the bit bit shift circuit 32 and according to the command from the bit shift command circuit 33! l1m bit error signal 6n
In the case where digital gain correction is performed in the n-bit p1-shift circuit 32 that performs bit shift by B-1- and no focus shift is performed (n=o)
The gain is 20-1, and the gain is 21-2 when carried by 1 bit (n=1).

In addition, the n-bit bit shift signal +, PWM to convert the output to an analog signal
The input to the circuit 34 is synchronized with the carrier wave signal of 4 for the PWMN path 34, and the gain is changed by repeating n=o and n=1 shifts alternately. =-2°10-21=1.5 (1) 2 2 is a1). Figure 4 shows the output waveform of the PWM circuit 34 (
When bit shift is returned) ff: Indicates. The PWMN path 34 is input to the low-pass filter 36 and converted to an analog signal. Figure 6 shows the human output lh characteristic of the gain correction circuit.
In the n-bit bit shift circuit 32, n-0, n=1,
Effects of the Invention According to the present invention described above, the loop transfer function of the speed system of the capstan motor is converted into a digital gain even in high-speed playback of a VTR. The compensation circuit compensates for the carrier wave component of the PWM output without amplifying it, and as a result fluctuations in the rotational speed of the capstan motor are extremely small, the reproduced image during high-speed reproduction is extremely stable, and digitally Due to gain correction, there is no gain variation il-j,
Furthermore, it is possible to provide a rotating body control device suitable for digital integrated circuits.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional example of a capstan motor control device during VTR playback, and FIG. 2 is a block diagram of a capstan motor control device during 411 playback of a VTR according to an embodiment of the present invention. Figure 3 is a block diagram of the main circuit in Figure 2, Figure 4 is a waveform diagram of the PWM circuit output waveform in Figure 3, and Figure 6 is a characteristic diagram showing the input/output characteristics of the digital gain correction circuit. ... Capstan shaft, 2 ... Pinch roller, 3 ... Magnetic tape, 4 ... Capstan motor, ... Digital period measuring circuit, 8 ...
...First D/man'RmLTJ path, 9...Control head, 1o...Second clock frequency, 1
1...Digital phase i1111 constant circuit, 12
...Reference signal generation circuit, 13...2nd
D-A conversion circuit, 14... Mixing circuit, 15.
River: Compensation circuit, 16: Motor drive circuit,
21...First digital gain correction circuit, 22
...Second digital gain correction circuit, 31...
...m-bit latch circuit, 32...n-bit bit shift circuit, 33...bit shift command circuit, 34...PWM circuit, 36...low band pass filter

Claims (2)

[Claims] (1) The signal obtained by the speed detection 2g provided on the rotating body is input to a digital period measurement circuit, the output of the digital period measurement circuit is input to a digital gain correction circuit, and the output of the digital gain correction circuit is digitally The analog conversion circuit is manually inputted into the rotary body drive circuit, and the rotary body control device part in which the rotary body is driven, the digital gain correction circuit has a unit of 11.5
By dividing the block into one or more blocks and providing a gain of 2n (n=o, ±1, ±2...) times within each block, the gain correction value can be adjusted to the desired value. A control device for a rotating body, characterized in that it is configured to be able to set a value. (2) The gain of the digital gain correction circuit is ==2
The control device for a rotating body according to claim 1, characterized in that n+-z2n+1 (n=o, -1=1.±2...).