JPS61172245A - Control method of magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To control variable speed reproduction by controlling a head drum motor and a capstan motor on time-division basis, detecting the simultaneous input of rotation detection signals of both motors, and modifying time-division processing according to the detection result. CONSTITUTION:Detection pulses obtained from a rotating speed detector 125 for the head drum motor 124 are inputted to the external interrupt terminal INT0 of a microcomputer 12. Detection pulses obtained from a rotating speed detector 129 for the capstan motor 128, on the other hand, are amplified and inputted to the external interrupt terminal INT1 of the microcomputer 21. The microcomputer 11 compares it with a reference value to generate a speed error signal. The error signal is added to a tracking error signal obtained by digitizing the output of a tracking error generating circuit 131 through an A/D converter 130 and filter operation is further performed, so that the result is outputted to a converter 126 as a motor driving command. The motor driving command which is converted into an analog value by the converter 126 drives the capstan motor 128 by a driving circuit 127.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to rotating helidene magnetic recording and reproducing devices, such as VTRs.
The present invention relates to a method for controlling rotation of a head drum and controlling tape feeding in a device such as the above.

2. Description of the Related Art Conventionally, in a VTR, as shown in FIG. 9, a head drum motor 100. Head drum control circuit 101. Capstan motor 102. Capstan control circuit 103
Each has its own dedicated control system. That is, a speed signal is obtained from the rotational speed detector 1o4 (for example, a frequency generator) of the henodotask, and the speed comparison circuit 105
A speed error signal is obtained by comparing with the reference speed. The speed error signal is sent to a drum motor drive circuit 107 through a filter 106 to drive the head drum motor 100. In this way, the head drano motor 100 rotates at a constant speed.

On the other hand, the same method is used for tape feeding. That is, a speed signal is obtained from the capstan's rotational speed detector 108, and compared with a reference speed by a speed comparison circuit 109 to obtain a speed error signal. After adding the speed error signal to the tracking error signal, the speed error signal is sent to the capstan motor drive circuit 111 through a filter 110, and then is sent to the capstan motor drive circuit 111.
to drive. and the capstan motor 10
2 speed control and knocking control.

Here, the filters 106 and 110 are used to enhance control performance in each control system. Note that the method for obtaining the trunking error varies greatly depending on the VTR standard, but in FIG.
The tracking error generation circuit 113 obtains the tracking error based on the signal obtained from the above.For example, there is a method of using a pyro-soto signal for tracking.

FIG. 4 is a block diagram of a general one-chip microcomputer used in the present invention. ALU (Arith
metic Logical Unit), instruction RO
M'.

Pointer register, data RAM, input/output ports.

Serial input/output interface, timer counter A,
B. External interrupt interfaces 0 and 1, interrupt control unit,
and system control are built into one chi knob. Here, the serial input/output interface, timer counters A, B, and external interrupt interfaces Q, 1 can function as interrupts. This one-chip microcomputer is a general one, and there is no problem even if it includes an AD converter, a DA converter, etc. in addition to the blocks shown in the figure.

FIG. 5 shows the hardware configuration of an embodiment of the present invention and a conventional example. A rotational speed detection pulse obtained from a rotational speed detector 125 of the head drum motor 124 is input to an external interrupt terminal (INTO) of a 1-chip microcomputer 121 (hereinafter abbreviated as microcomputer). Inside the microcomputer 121, after comparing the speed with a reference value and performing filter calculations as a speed error, the DA converter 12
2, the result is output as a motor drive command. The motor drive command converted into an analog quantity by the DA converter 122 drives the head drum motor 124 by the head drum motor drive circuit 123 .

The above is an outline of the head drum motor control section.

The rotation speed detection pulse obtained from the rotation speed detector 129 of the capstan motor 128 is amplified and then input to the external interrupt terminal (I NT 1) of the microcomputer 121.

Inside the microcomputer 121, a speed error is obtained by comparing with a reference value. This C speed error signal and the tracking error signal obtained by converting the output of the tracking error generation circuit 131 into Dipantal 9 by the AD converter 130 are added, and after further filtering is performed, the result is used as a motor drive command. Output to DA converter 126. DA converter 126
The motor drive command converted into an analog quantity by the capstan motor drive circuit 127 drives the capstan motor 128 . The above is an outline of the capstan motor control section.

6 to 8 are flowcharts of the processing procedure in the microcomputer 121 of FIG. 5, and the explanation will be made along these flowcharts. FIG. 6 shows processing from power-on (reset) and processing other than the speed detection pulse. Microcomputer 12
1 starts the initialization program 200 without switching when the power is turned on. The initialization program includes initialization of the built-in RAM, initialization of the output port, initialization of the DA converter, and the like. Next, the built-in timer counter A is set (block 201). The timer counter A is not used as an interrupt, but an internal clock is counted, and the process continues even if an overflow occurs. Next, at block 202, speed reference values for the head drum motor 124 and capstan motor 128 are set. In reality, it corresponds to the period of the pulse from each rotation speed detector,
For example, a value equivalent to 1x speed playback is set. Next, in block 203, the microcomputer 121 is enabled to receive head drum motor speed detection pulses and capstan motor speed detection pulses by allowing interrupts from INTo and lNT1. In the above explanation, everything except the interrupt processing is basically completed, and the microcomputer 121 does not do anything except when an interrupt occurs.

Therefore, other processing (completely different processing) can be performed between one interrupt processing and the next interrupt processing. As an example, as shown in block 204, a speed change command is read from the input port, and if there is a speed change command, the processor 1. Then, the process moves to block 205, where the speed reference value set in block 202 is changed, for example, for slow motion. If there is no change command, nothing is done and the process returns to block 204 again. The above processing is the processing when no interrupt occurs.

Next, using FIG. 7, we will explain the processing at the time of an INTO interrupt, that is, when a pulse is input from the head drum rotation speed detector 125.When an INTO interrupt occurs, block 2o , prohibits other interrupts. (Depending on the type of microcomputer 121, other interrupts may be automatically prohibited. In that case, this block 210 is unnecessary.) This means that other interrupts may be disabled before the interrupt time is known. This is to prevent the time that you want to know from changing significantly due to the time being entered.

Next, in block 211, the value of counter A, which was set in block 201 to repeat the built-in overflow, is read. The value is stored in memory T0.

Block 212 then allows another interrupt, here lNT1. (INTO itself is not permitted.) Next, in block 213, the difference between the read time TA and the previous read time TA' is determined, ie, the pulse period PA is determined.

Next, in block 214, the resulting pulse period PA
The difference between the period reference PAref and the period reference PAref, that is, the period error is determined. This periodic error corresponds to the speed error. Next, in block 215, a filter calculation is performed based on the obtained speed error to obtain a motor drive command. Then, in block 216, preparations are made for the next time by transferring the currently read time value TA to the previous time value TA', and in block 217, an interrupt of INTo is enabled,
Ends the INTo interrupt processing.

Next, with reference to FIG. 8, a description will be given of the processing at the time of the lNT1 interrupt, that is, when a pulse from the capstan rotational speed detector 129 is input. ! First, when the lNT1 interrupt occurs, in block 220, the value of timer counter A is read and the value is stored in memory TB. Engineering NT1
For interrupts, INTo interrupts are not prohibited so that the head drum pulse may be input at any time. Next, in block 221, the difference between the currently read value TB and the previous value TB', that is, the period PB, is determined.

Then, in block 222, the difference between the period PB and the reference period PBref, that is, the period error is determined. The period error corresponds to the speed error. Then, in block 223, a tracking error is added to this error value, and based on this value, a filter operation is performed in block 224 to obtain a motor drive command value. Next, in block 225, the time value TB read this time is transferred to the previous value TB', and in block 226, preparations are made for the next interrupt occurrence by enabling interrupts of lNT1, and Finish the process.

Problems to be Solved by the Invention In the example shown in Fig. 9, there are two motors: a drum motor and a capstan motor.
A dedicated control circuit was required for each motor. Further, in each dedicated circuit, when performing special reproduction (slow motion or high speed reproduction), it is necessary to perform speed reference switching, and it is necessary to prepare the reference value. Therefore, in order to perform various special reproductions, it is necessary to prepare many reference values. In this way, in the example of FIG. 9, circuits are required depending on each function, resulting in a lack of flexibility and versatility.

In addition, in the examples shown in FIGS. 5, 6, 7, and 8,
Since two motors are controlled simultaneously using a single-chip microcomputer, there is almost no need for each circuit, and the same circuit can be used in a time-sharing manner.

Furthermore, it is easy to handle various special reproductions. In other words, it is only necessary to switch the reference value using software, which provides flexibility and versatility.

If two signals are input at the same time, only one of them can be processed, resulting in a problem in which the accuracy of the control system deteriorates. For example, as described in the conventional example, when drum control is given priority, if a capstan pulse is detected and the drum pulse processing is started immediately after the INT1 interrupt occurs, an INTQ interrupt is generated without being able to read the time of the capstan pulse. and starts drum control processing. After the drum control process is completed, the process returns to the capstan control process. Therefore, the time reading of the capstan pulse may be significantly delayed. Also, for this reason, there is a method to prohibit processing using drum pulses during the capstan pulse time reading period, but this method does not allow drum pulse processing. An adverse effect occurs on lj control. This is because in a rotating head helical scan VTR, there are two functions: head rotation speed control (drum control) and tape feed control (capstan control).
This is because the control accuracy required for each control is different.

That is, precision is required for head rotational speed control, and if the rotational unevenness is large, the reproduced image on the TV screen will be shaken, making it extremely difficult to view.

For this reason, priority is given to drum pulse processing.

Means for Solving the Problems In the present invention, in order to solve the second problem, the throat drum morph and capstan motor are controlled in a time-sharing manner, and the rotation detection signals of the two motors are input at the same time. is detected, and the time-sharing processing method is modified based on the detection result.

In the present invention, the timing at which the rotation detection pulse of the head drum will be obtained is predicted, and if the rotation detection pulse of the capstan is detected during the period immediately before the timing when the rotation detection pulse is obtained, the timing at which the rotation detection pulse of the capstan will be obtained is predicted. Instead of using the capstan detection pulse, the next capstan detection pulse is used, and the capstan detection pulse is frequency-divided and used with equal constraints to eliminate processing delays due to time-division processing.

EXAMPLE An example of the present invention will be described below. The configuration of this embodiment, particularly the hardware configuration, is as shown in FIG. 5. That is, it is the same as that described in the conventional example. The internal configuration of the one-chip microcomputer 121 in FIG. 5 is as shown in FIG. 4.

This is also the same as that explained in the conventional/conventional example. Furthermore, among the processing procedures in the microcomputer 121, processing procedures that do not respond to interruptions are shown in FIG. That is, this is also the same as before. Therefore, the explanation regarding the above is omitted,
In the following, we will mainly describe the parts that are different from the conventional method, that is, the processing procedures using interrupts.

FIG. 1, FIG. 2, and FIG. 3 are flowcharts showing the processing procedure in this embodiment. This procedure will be explained below. Figure 1 shows an interrupt caused by drum rotation pulse detection, I
This is the NTO processing procedure.

First, when an interrupt is accepted, other interrupts are processed.

It is prohibited in R1. As a result, other interrupts are not accepted, and the process immediately moves to block 2, reads the value of timer counter B, and stores it in memory TA. Next, in block 3, timer B is started. The constant of timer B is set to a value slightly shorter than the drum rotation pulse period.

Next, in block 4, other interrupts are enabled. This allows the capstan pulse, that is, the interrupt of the NT1. Then, in block 5, a flag indicating that lNT1 has been in a prohibited state is cleared. Then, in block 6, the pulse period is calculated, and in block 7, it is compared with the reference value to obtain an error value.
In block 8, a filter calculation is performed based on the error value to obtain a drum motor drive command. Furthermore, in block 9, the value TA read this time is transferred to the previous value TA', and the process 1. At step 10, the INTo interrupt is permitted, preparations for the next time are made, and the interrupt processing is completed.

FIG. 2 shows the interrupt processing procedure of timer B started as shown in FIG. When a timer B interrupt occurs, lNT
1, that is, interrupts caused by capstan pulses are prohibited, and then a flag indicating that lNT1 is prohibited is set. This completes the timer B interrupt processing. That is, this timer B does not process capstan pulses during the period immediately before drum pulse input and outside of detection.

Therefore, when a drum pulse is input, the microcomputer is used exclusively for drum control, and the drum is controlled with high precision.

FIG. 3 shows the interrupt processing by NT1, that is, the capstan rotation pulse.

This is because when an interrupt occurs, the period of the rotation pulse when reading the value of the timer counter A becomes long, and even without taking the measures described below, the ratio of the detection delay time to the period becomes small. Furthermore, the low speed means that the amount of tape transported per unit time is small, so the influence of relative rotational speed fluctuations is extremely small.

If it is low speed mode in block 21, block 2
Proceed to step 2. That is, as in the prior art, the pulse interval is measured in block 22, the speed error is obtained by comparing it with the reference value in block 23, the tracking error signal is added in block 24, and the filter calculation is performed in block 25. and obtain the motor drive command value. Next, in block 26, the current time TB is transferred to the previous time TB', and in block 27, the INT1 interrupt is re-enabled to prepare for the next interrupt, and the interrupt processing ends.

If it is not the low speed mode in block 21, the process proceeds to block 28, where it is checked whether the flag set by timer B, that is, the NT1 unused flag is set. That is, it is checked whether the pulse that causes the current interrupt is generated while the lNT1 interrupt is disabled.

If the NT1 unused flag is set to seven, the NT1
This means that an interrupt factor has occurred while interrupts are disabled. If the NT1 unused flag is set in block 28, the process advances to block 29. At block 29, the 5KIP flag is set. This flag indicates that the timing TB read this time is not accurate, so the subsequent processing is to be skipped. Furthermore, in block 30, the NTi unused flag is cleared since it is no longer needed. The process then proceeds to block 27, where the next interrupt can be accepted, and the interrupt processing ends.

On the other hand, if the lNT1 unused flag continues to be set in block 28, the process advances to block 31 to check whether the 5KIP flag is set. That is, it is checked whether the previous process was skipped. If the 5KIP flag is not set, the process proceeds to block 22, where processing similar to the conventional one is performed, that is, comparison of one cycle (speed) of period calculation, addition of torrent king error, and filter calculation. Then, preparations are made for the next interrupt processing and the interrupt processing is ended. If the 5KIP flag is set in block 31, the process proceeds to block 32. 5K thereafter
Since the IP flag is unnecessary, it is cleared in block 32. Next, in block 33, the current time TB
and the previous time TB'.

Unlike the others, the values obtained here are not periodic. This is because the previous time TB' has been skipped in the previous process, so it remains the same as the time before the previous one. Therefore, the obtained difference has a value equivalent to twice the period. Therefore, the error is calculated by processing shown in blocks 34 and 35. That is, the reference value PBref is subtracted twice from the value PB obtained in block 33. This is treated as an error and the process proceeds to block 24, where the tracking error is added and filter calculation is performed to obtain the cab stylus motor drive command value. Then, preparations for the next interrupt processing are performed in blocks 26 and 2a, and the interrupt processing is completed.

In other words, the process shown in FIG. 3 uses speed information averaged using the previous time and the next time when the obtained time TB cannot be accurate. This average is equivalent to dividing the output of a conventional rotational speed detector. In addition, this method divides the frequency of this signal to remove the influence only when an inconvenient signal or a signal that has an adverse effect on accuracy is received as an input signal.

Effects of the Invention From the above description, the present invention can improve the performance of the capstan control system without increasing the circuit scale, without reducing the performance of the head drum control system, which is the key to the performance of a helical scan VTR. It is possible to provide a method that can easily maintain the same speed and control such as variable speed playback, and its effects are great.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing a processing procedure for drum rotation control in an embodiment of the present invention, and FIG. 2 is a flowchart 1 showing a prediction timer interrupt processing procedure in the same embodiment.
, FIG. 3 is a flowchart showing the processing procedure of capstan control in the same embodiment. Fig. 4 is a block diagram showing an example of the internal configuration of the one-knob microcomputer used in the present invention, Fig. 5 is a circuit diagram of the control section used in the present invention, and Fig. 6 is a diagram showing the control procedure used in the present invention. , Flowchart 1 showing the procedure of the part that does not process interrupts. FIG. 7 is Flowchart 1 showing the drum control processing procedure according to the conventional processing procedure in the configuration of FIG. 5.
8 is a flowchart showing a capstan control procedure according to the conventional procedure in the configuration of FIG. 5, and FIG. 9 is a block diagram of a control circuit in a conventional VTR. 121...One-chip microcomputer, 122
．． 126...DA converter, 123,127...
...Motor drive circuit, 124...Head drum motor, 128...Capstan motor, 125゜1
29...Rotation speed detector. Figure 1 Figure 2 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] A magnetic head is mounted on a rotating drum, a magnetic tape is wound around the rotating drum, and the magnetic tape is transported at a constant speed to record and reproduce information signals on the magnetic tape as a group of discontinuous recording tracks. In a magnetic recording and reproducing apparatus having a rotational speed detection means of the rotary drum and a tape transport speed detection means, the time of the output signal from the rotational speed detection means of the rotary drum is measured, and the time interval between the measured times is used to determine the time of the output signal. Calculate the rotation speed of the rotating drum, measure the time of the output signal from the tape transfer speed detection means, calculate the tape transfer speed based on the interval between the measured times, and calculate the rotation speed of the rotating drum and the tape transfer speed. A method of controlling the rotational speed of the rotating drum in a time division manner, the method predicts the time at which a signal is output from the rotational speed detection means of the rotating drum, and the signal output from the rotational speed detection means of the rotating drum is controlled from a time immediately before the predicted time. The time measurement of the output signal from the tape transport speed detection means is stopped during the period up to the time, and if the output signal from the tape transport speed detection means is detected during this stop period, the previously detected tape transport speed detection the time value of the output signal from the means;
1. A method of controlling a magnetic recording/reproducing apparatus, characterized in that a tape transport speed is calculated based on a difference between a time value of an output signal from a tape transport speed detecting means to be detected next time.