JPH0352583A - Controller for drum motor - Google Patents

Abstract

PURPOSE:To remove the nonuniformity of FG by controlling a drum motor by a phase signal and a speed difference section signal from the phase signal at the initial stage of control while storing the 1/K times of the speed control signal of a frequency signal and controlling the drum motor by a deviation- section removal-speed difference section signal from the frequency signal a phase difference section after the initial stage. CONSTITUTION:A phase difference section signal 200 and a speed difference section signal 100 are detected by detectors 7, 6 from a D-PG signal from a pulse generator 2 at the initial stage of the control of a drum motor 1, and an addition result by an adder 11 of both signals 100, 200 is integrated by a loop filter 13, thus controlling the motor 1. A speed difference section signal 300 is detected by a detector 8 from the D-FG signal from a frequency generator 3 during that time, and the value of the signal 300 is multiplied by 1/K by a signal nonuniformity removal circuit 9 and stored. The circuit 9 forms a feedback type comb-shaped filter and removes the nonuniformity of FG after a fixed period, a signal 400, in which there is no nonuniformity, and the signal 200 are added by an adder 10, and the result is integrated by a loop filter 12, thus controlling the motor 1.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to a drum control device for controlling the rotational speed and phase of a rotating magnetic head used in a video tape recorder (VTR), and particularly relates to a drum control device for controlling the rotational speed and phase of a rotating magnetic head used in a video tape recorder (VTR). This invention relates to removing deviations in control signals.

(Prior Art) A household VTR is provided with a drum motor control device that controls the rotational speed and phase of a drum motor that drives a rotating drum mounted with a magnetic head. The drum motor includes a frequency generator (FG) that generates a signal having a frequency proportional to its rotational speed, and a pulse generator (FG) that generates a pulse when its rotational phase reaches a predetermined phase.
PG) is installed. Therefore, the drum motor control device inputs these FG pulses and PG pulses to control the rotational speed and phase of the drum motor. However, since these frequency generators and pulse generators are attached to the rotating shaft of the drum motor, the amplitude and phase of the generated pulses may vary depending on the mounting accuracy, eccentricity of the rotating shaft, and the influence of the motor's field. The so-called FG unevenness occurs. Therefore, even though the number of rotations of the drum motor is constant, the frequency of the FG signal is controlled to be constant by the control device for the drum motor, so that the number of rotations of the drum motor conversely changes. There was a problem with this.

Therefore, as a method to solve this problem, a control method that removes the component (ys difference component) that is an integral multiple of the drum motor's rotational speed due to installation errors and eccentricity, which are the causes of FG unevenness, is proposed in a technical report by the Television Society of Japan. Figure 3 is a block diagram showing this control system. This method detects the amount of deviation between the period of the FG signal and its target value (the center value when there is no FG unevenness), and subtracts the amount corresponding to the deviation from the FG signal period measurement result. It is called a digital comb type filter. To explain the operation of this feedback type digital comb filter in detail, registers 181 to 186 each hold deviation data p1 to D6 due to FG unevenness, and deviation data D66 held in register 8 is multiplied by K by multiplier 19. be done. After that, this KxD
6 is subtracted from the input data X by the subtractor l6, and the obtained result is output as a signal Y.
The deviation data D6 held in the register 86 is added by the adder 19, and this becomes the new data held in the register 81. Therefore, if the input data Corrections are made to increase or decrease. For example, input data
If there is a positive steady-state deviation, the value of register 86 is
The output signal Y increases until it becomes a negative number, and then settles to a value that increases or decreases around θ.

However, the above filter is an example in which six FG pulses are output per rotation of the drum motor, and K is a constant such that O<K<1. In this filter, by making K sufficiently smaller than 1, it is possible to obtain a high Q characteristic with as little influence on the drum servo system as shown in FIG. 4. In addition, in FIG. 4, when each transfer function of registers 181 to 186 is set to Z-1, Y/X=(1-Z)/(1-(1
-K)Z'}T-6 The indicated frequency characteristics are displayed.

Although the conventional FG unevenness removal method using a feedback type digital comb filter can effectively remove FG unevenness that is synchronized with the motor rotation speed,
Since a feedback method is adopted, there is a drawback that the time required for the effect to appear varies depending on the degree of FG unevenness. Moreover, if there is FG unevenness that exceeds the control range of the drum servo system, there is a drawback that no effect can be expected.

(Problems to be Solved by the Invention) As described above, in the signal unevenness removing device using the conventional feedback type digital comb filter, the FG is synchronized with the rotational speed of the motor.
Although it is possible to effectively remove unevenness, since a feedback method is adopted, there is a drawback that the time required for the effect to appear varies depending on the degree of FG unevenness. Moreover, if there is FG unevenness to the extent that it deviates from the control range of the drum servo itself, there is a drawback that the effect cannot be expected at all.Therefore, the present invention eliminates the above-mentioned drawback, and the present invention aims to reduce the degree of FG unevenness. It is an object of the present invention to provide a control device for a drum motor equipped with a feedback type digital comb filter that always has a constant response and an effect of removing FG unevenness without dependence.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a signal detecting means for obtaining a speed signal corresponding to the rotational speed of a drum motor and a phase signal corresponding to the rotational phase of the motor, a first speed detection means for detecting a speed difference signal between the phase signal and a target rotational phase of the drum motor; and a phase detection means for detecting a phase difference signal between the phase signal and a target rotational phase of the drum motor, a storage means for storing the deviation component included; a signal obtained by subtracting data obtained by multiplying the deviation component stored in the storage means by K from the speed difference signal as a speed feedback signal; In a drum motor control device equipped with a digital comb-shaped filter, the control device includes means for storing a value obtained by adding the deviation component in the storage means as a new deviation component. a second speed detection means for deriving a certain speed difference signal from the phase signal; a second speed difference signal obtained from the second speed detection means for a certain period of time as a speed feedback signal; a first control means for controlling the drum motor using a phase difference signal obtained as a phase feedback signal; an initial value setting means for storing a signal obtained by multiplying the speed control signal obtained from the detection means by 1/K in the storage means of the digital comb filter; and a signal obtained by multiplying the speed control signal by 1/K by the initial value setting means. After storing the first speed difference signal in the storage means, the first speed difference signal obtained from the first speed detection means is supplied to the comb filter, and the obtained deviation component removed speed difference signal is used as the speed feedback signal, and the phase difference signal is set as the speed feedback signal. and second control means for controlling the drum motor using a phase difference signal obtained from the detection means as a phase feedback signal.

(Function) In the drum motor control device of the present invention, the second speed detection means derives a speed difference signal, which is the difference between the drum motor and the target rotational speed, from the phase signal. The first control means controls the drum motor by using the second speed difference signal obtained from the second speed detection means as a speed feedback signal for a certain period of time and using the phase difference signal obtained from the phase detection means as a phase feedback signal. do. The initial value setting means generates a signal obtained by multiplying the speed control signal obtained from the signal detection means by 1/K in a digital comb shape during a period when the drum motor is controlled based on the second speed difference signal and the phase difference signal. It is stored in the storage means of the filter.

This initial value setting means changes the speed control signal to 1/K.
After storing the multiplied signal in the storage means, the second control means supplies the first speed difference signal obtained from the first speed detection means to the comb filter to generate a deviation component removed speed difference signal. is used as a speed feedback signal, and the phase difference signal obtained from the phase detection means is used as a phase feedback signal to control the drum motor.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings, in which the same parts as those of the conventional example are denoted by the same reference numerals. FIG. 1 is a block diagram showing an embodiment of a drum motor control device of the present invention. 1 is a drum motor that drives a rotating drum equipped with a magnetic head; 2 is a pulse generator that generates a pulse D-PG that corresponds to the rotational phase of drum motor 1; and 3 is a frequency that corresponds to the rotational speed of the drum motor. signal D with
- A frequency generator that generates FG, 4 a Schmitt circuit that shapes the waveform of the pulse D-PG, 5 a Schmidt circuit that shapes the waveform of the signal D-FG, and 6 rotation of the drum motor 21 from the pulse D-PG. A speed detector 7 detects a speed difference signal 100 that controls the speed, and 7 is a phase difference signal 20 that controls the rotational phase of the drum motor 1 from the pulse D-PG.
8 is a speed detector that detects a speed difference signal 300 that controls the rotational speed of the drum motor 1 from the signal D-FG, and 9 is a signal unevenness remover that removes FG unevenness of the speed difference signal 300. circuit (feedback type digital comb filter); 10 is an adder that adds the speed difference signal 400 output from the signal unevenness removal circuit 9 and the phase difference signal 200 output from the phase detector 7; l1 is the speed detector 6; an adder 12 for adding the speed difference signal 100 outputted from the phase difference signal 100 and the phase difference signal 200 outputted from the phase detector 7;
is a loop filter that integrates the addition result of the adder 10, 1
3 is a loop filter that integrates the addition result of the adder 1l;
14 is a switch that selects and outputs the output of either the loop filter 12 or 13, and l5 is a driver circuit that amplifies the rotation control signal output from the switch 14.

FIG. 2 is a block diagram showing a detailed example of the signal unevenness removing circuit 9 shown in FIG. 1. 16 is a subtracter that subtracts the output signal of multiplier 17 from input signal 300, 17 is a multiplier that multiplies the signal held in register l86 by K, and 181 to 186 sequentially hold data input from terminal C of switch 20. Register 19 is an adder that adds the output signal 400 of subtracter 6 and the holding signal of register 186, and outputs the addition result to terminal a of switch 20; 21 is a multiplier that multiplies the input signal 300 by 1/K and outputs the result to terminal b of the switch 20.

Next, the operation of this embodiment will be explained. In FIG. 1, the switch 14 is switched to the terminal b side when controlling the drum motor at an initial stage such as after the power is turned on or the system is turned on. The speed detector 6 and the phase detector 7 detect a speed difference signal 100 and a phase difference signal 200 from the pulse D-PG output from the pulse generator 2, respectively, and output these signals to the adder 11. The result of addition of the two signals outputted from the adder 11 is integrated by the loop filter 13 and inputted to the driver circuit 15 via the switch 14. Therefore, the driver circuit 15 amplifies the input pulse D-PG system rotation control signal and outputs it to the drum motor 1. In this way, when the phase and speed of the drum motor 1 are controlled by the pulse D-PG system, the speed detector 8 detects the speed difference signal 300 from the D-FG signal output from the frequency generator 3 and uses it. It is output to the signal unevenness removal circuit 9.

Next, the operation of the signal unevenness removing circuit 9 at this time will be explained. First, the switch 20 shown in FIG. 2 is connected to the drum motor 1 because the switch 14 shown in FIG.
When the servo is locked, it is switched to the terminal b side.

Therefore, the speed difference signal 300 output from the speed detector 8 in FIG. The registers 181 to 186 operate in synchronization with the pulse D-FG, and the output signal of the multiplier 21 is sequentially transmitted to the registers 181 to 18.
6. After that, switch l is synchronized with D-PG.
4 and 20 are switched to the terminal a side in conjunction. As a result, the signal unevenness removing circuit 9 forms a feedback comb filter, the subtracter 16 removes the FG unevenness component from the speed difference signal 300, and the speed difference signal 400 without deviation is sent to the adder 10.
is output to. On the other hand, when the phase detector 7 detects the phase detection signal 200 from the pulse D-PG, it is sent to the adder 10.
Output to. Therefore, the adder 10 outputs the speed difference signal 40
0 and the phase difference signal 200 and output the result to the loop filter 12.

The result of addition of both signals outputted from the adder 10 is integrated by the loop filter 12 and inputted to the driver circuit 115 via the switch 14. Therefore, the driver circuit 15 amplifies the input signal D-FG and pulse D-PG system rotation control signal and outputs the amplified signals to the drum motor 1. In this way, the phase and speed of the drum motor 1 are controlled by the pulse D-PG system and the signal D-FG.

According to this embodiment, the rotational speed and rotational phase of the drum motor 1 are initially controlled only by the pulse D-PG, and the speed detection signal of the signal D-FG system obtained at that time is sent to the registers 181 to 181 of the signal unevenness removal circuit 9. 186 and the signal D-FG
After determining the initial value of the amount of deviation that Since the signal unevenness removing circuit 9 is operated to remove the FG unevenness component from the speed difference signal 300, the FG unevenness removal effect can be obtained within a certain period of time regardless of the degree of FG unevenness, and the drum control device can be controlled. Even if FG unevenness exists to the extent that it deviates from the range, the above-mentioned FG unevenness removal effect can be obtained. Further, by using the above method, the accuracy of the signal D-FG can be lowered, and costs can be reduced. Therefore, for example, it is also possible to use a switching pulse for phase switching of the drum motor 1 as a D-FG signal.

〔Effect of the invention〕

As described above, according to the drum motor control device of the present invention, constant responsiveness and F
It is possible to obtain the effect of removing G unevenness.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the drum motor control device of the present invention, FIG. 2 is a block diagram showing a detailed example of the signal removal circuit shown in FIG. 1, and FIG. 3 is a block diagram showing a detailed example of the signal removal circuit shown in FIG. FIG. 4 is a block diagram showing an example of a control device for a drum motor, and FIG. 4 is a characteristic diagram showing signal removal characteristics of the circuit shown in FIG. 3. ■...Drum motor 3...Frequency generator 2.
...Pulse generator 6, 8...Speed detector 7...
・Phase detector 9...signal unevenness removal circuit 10,
IL19... Adder 12, 13... Loop filter l4, 20... Switch 15... Driver circuit 16... Subtractor 17, 21... Multiplier 1
81-186...Register

Claims (1)

[Claims] a signal detection means for obtaining a speed signal corresponding to the rotational speed of the drum motor and a phase signal corresponding to the rotational phase of the motor; and a first signal detection means for detecting a speed difference signal between the speed signal and a target rotational speed of the drum motor. a speed detecting means; a phase detecting means for detecting a phase difference signal between the phase signal and a target rotational phase of the drum motor; A signal obtained by subtracting data multiplied by the deviation component stored in this storage means from the difference signal is used as a speed feedback signal, and a value obtained by adding this speed feedback signal and the deviation component is used as a new deviation. In a drum motor control device comprising a digital comb filter having means for storing components in the storage means, a speed difference signal, which is a difference from a target rotational speed of the drum motor, is derived from the phase signal. and a second speed difference signal obtained from the second speed detection means for a certain period of time as a speed feedback signal, and a phase difference signal obtained from the phase detection means as a phase feedback signal to drive the drum motor. and a first control means for controlling the speed control signal obtained from the signal detection means during a period in which the drum motor is controlled based on the second speed difference signal and the phase difference signal. initial value setting means for storing the multiplied signal in the storage means of the digital comb filter; and after the initial value setting means stores in the storage means a signal obtained by multiplying the speed control signal by 1/K; A deviation component removed speed difference signal obtained by supplying the first speed difference signal obtained from the speed detection means to the comb filter is used as a speed feedback signal, and a phase difference signal obtained from the phase detection means is used as a phase feedback signal. a second controlling said drum motor as
1. A control device for a drum motor, comprising: control means.