KR19980059129A - How to measure the rotational speed of V-Cal drum motor - Google Patents

Abstract

The present invention relates to a method for measuring the rotational speed of a BC head drum motor, and in particular, by comparing and measuring the time at which the counter electromotive force generated from the coil reaches an arbitrary reference voltage to determine the rotational speed of the drum motor according to the result. The present invention relates to a rotational speed measurement method of a V-Cal drum drum motor.

To this end, the present invention, in the V-Cal head drum motor for supplying a drive signal to the three-phase coil wound on the core of the stator, determining whether the back electromotive force generated from the three-phase coil is zero crossing, zero in the step Measuring the voltage of the counter electromotive force in the case of crossing; determining whether the difference between the reference voltage and the counter electromotive force voltage output is 0 in the step; and if it is determined that the difference between the reference voltage and the counter electromotive force voltage is 0 in the step, stopping the voltage measurement of the counter electromotive force; Comparing the time between the reference voltage and the counter electromotive force voltage difference and the set reference time after the step; controlling the speed of the drum motor slowly when the measurement time is less than the reference time; If it is faster than the reference time it consists of a step of controlling the speed of the drum motor fast.

Description

How to measure the rotational speed of V-Cal drum motor

The present invention relates to a method for measuring the rotational speed of a BC head drum motor, and in particular, by comparing and measuring the time at which the counter electromotive force generated from the coil reaches an arbitrary reference voltage to determine the rotational speed of the drum motor according to the result. The present invention relates to a rotational speed measurement method of a V-Cal drum drum motor.

In general, the VR signal system has a very small dimension of recording a video signal, a track width of about 0.2-0.02 mm, a recording wavelength of about several microns, and is recorded in the tape width direction.

Therefore, during recording and playback, it is necessary to control the head drum rotation so as not to change as the time axis of the video signal changes.In order to maintain precise tracking control during playback, the head drum rotation and the tape running state (speed and position relationship) It is necessary to hold it as in recording, and a pulse generator (PULSEGENERAROR: hereinafter referred to as FG) is used for VRC for accurate speed control.

Looking at the FG generator and process as described above with reference to Figure 1, the head drum 71, the head of the V-Cal 70 is mounted, the drum motor 72 for driving the head drum 71, and A FG detection pattern 75 formed on the rotor 73 and the stator 74 side of the drum motor 72 to generate a speed pulse signal, and a sinusoidal speed pulse signal generated from the FG detection pattern 75. A hysteresis amplifier 76 for converting and amplifying a square wave into a square wave, and a microcomputer 77 for calculating the timing of the speed pulse signal input from the hysteresis amplifier 76 to control the speed of the drum motor 72.

In addition, the FG detection pattern 75 has a plurality of rotor magnets, that is, a plurality of permanent magnets on the rotational circumference of the cylindrical member formed with a plurality of permanent magnets, for example, magnets rotating in 24 permanent magnets having different polarities. And a detection pattern 80 arranged in a circle on the fixed printed circuit board 79 so as to face the magnetizing surface of the rotary magnet 78. As shown in FIG.

Here, the rotating magnet 78 is formed integrally with the rotor 73 to generate a voltage having a frequency of 1/2 the number of poles of the rotating magnet 78 each time the rotor 73 rotates, and The detection pattern 80 is formed on the stator 74 side and is integrally formed on the fixed printed circuit board 79 on which the armature coil, the position detection element, and the electronic component for driving are disposed.

On the other hand, looking at the operation of the conventional FG circuit configured as described above, when the playback mode or recording mode is set first, the microcomputer 77 drives the drum motor 72 to rotate the head drum (71).

That is, the rotor 73 rotates due to the electromagnetic action of the stator 74 and the rotor 73 of the drum motor 72, and thus the head drum 71 also rotates through the rotation shaft 81. The rotation magnet 78 of the FG detection pattern 75 integrally formed in the rotor 73 also rotates according to the rotation of the rotor 73.

Accordingly, a rotation detection voltage, that is, a sinusoidal speed pulse voltage is generated in the detection pattern 80 of the FG detection pattern 75 at a position opposite to the rotation magnet 78, and is input to the hysteresis amplifier 76. The equation amplifier 76 performs waveform conversion amplification on the input sinusoidal speed pulse voltage and inputs the waveform to the microcomputer 77 as a square wave pulse signal.

Therefore, the microcomputer 77 compares and judges the input speed pulse signal (720 pulses per second in the normal case) to stably control the current drum motor 72 according to the set mode.

In such a conventional head drum motor, the FG generator forms a complex detection pattern 80 on the fixed printed board 79. Since the rotating magnet 78 must be formed with a certain gap (GAP) facing the detection pattern, the manufacturing cost increases accordingly, and the rotating magnet 78 is placed on the rotation circumference of the rotor 73 by N, The problem is that the FG generator becomes considerably complicated by multiple division magnetization with the S pole.

In order to solve the above problems, the present invention compares and measures the time when the counter electromotive force generated from the coil reaches an arbitrary reference voltage and determines the rotational speed of the drum motor according to the result. It is an object of the present invention to provide a method for measuring the rotational speed of a V-Cal drum drum motor that simplifies the structure of the drum motor by removing the FG pattern formed in the drum motor.

The present invention for realizing the above object is to determine whether the reverse electromotive force generated from the three-phase coil is zero crossing in the V-Cal head drum motor for supplying a drive signal to the three-phase coil wound on the stator core in the microcomputer Step, measuring the voltage of the counter electromotive force in the case of zero crossing, determining whether the output voltage difference between the reference voltage and the counter electromotive force voltage is 0 in the step, if it is determined that the difference between the reference voltage and the counter electromotive force voltage is 0 in the step Stopping the measurement, comparing the time when the difference between the reference voltage and the counter electromotive force voltage becomes zero and setting the reference time, controlling the speed of the drum motor slowly when the measurement time is less than the reference time; In this step, if the measurement time is earlier than the reference time, the speed of the drum motor is controlled quickly. It is made up of steps.

1 is a block diagram of a pulse generator of a general BC head drum motor.

2 is a waveform diagram of back EMF and FG generated from a three-phase coil according to the present invention.

Figure 3 is a voltage rise waveform with respect to the time of the back EMF in accordance with the present invention.

Figure 4 is a flow chart of the rotational speed measurement according to the present invention.

* Explanation of symbols for main parts of the drawings

71: head drum 72: drum motor

73: rotor 74: stator

75: FG pattern 76: hysteresis amplifier

77: micom 78: rotating magnet

79: fixed printed circuit board 80: FG detection pattern

Hereinafter, described in detail by the accompanying drawings as follows.

When the rotor is rotated by applying a current to the three-phase coil of the drum motor in the microcomputer (not shown), a sinusoidal counter electromotive force having a U, V, and W three phase is generated from the three phase coil as shown in FIG. Zero crossing appears.

In other words, the zero crossing portion of the sine wave of U, V, and W phases is used to obtain the FG signal with the same on / off period, and zero crossing is used as a reference for the rotational speed measurement. This makes it possible to determine the speed faster even if the actual FG is not one or half cycle time.

Therefore, the sine waves of U, V, and W phases have the same period or zero crossing, and at this time, the counter electromotive force waveform has a calculated time to reach a certain value with respect to the reference rotational speed. The period at which the back EMF reaches a certain value is also faster or later.

Therefore, the slope of the counter electromotive force is also changed, and there is a difference in the time to reach the reference voltage. If this time is judged by the microcomputer, the rotation speed of the drum motor can be judged before the period of FG or within the desired electric angle. .

Referring to FIG. 3 in detail, T2 is a time at which the reference voltage is reached at normal rotation, T1 is a time when the rotation speed is fast, and T3 is a time at which the reference voltage is reached when the rotation speed is slow, and the counter electromotive force is zero. When crossing, the measurement is started by sending the time measurement signal to the microcomputer.The counter electromotive force is input to the same circuit as the differential amplifier, and when the difference with the reference voltage becomes 0, it sends the time measurement stop signal to the microcomputer. The speed of rotation can be determined.

This process will be described in detail with reference to the flowchart shown in FIG. 4.

First, the microcomputer (not shown) detects the counter electromotive force generated from the three-phase coil, determines whether the counter electromotive force is a zero crossing point (S1), and then, in the case of zero crossing, measures the voltage of the counter electromotive force (S2).

At this time, it is determined whether the difference between the reference voltage and the counter electromotive voltage is 0 (S3). When it is determined that the difference between the reference voltage and the counter electromotive force voltage is 0, the voltage measurement of the counter electromotive force is stopped (S4), and then the comparison time between the reference voltage and the counter electromotive force voltage difference becomes zero and the set reference time from zero crossing point (S5). )

Therefore, when the time when the reference voltage and the counter electromotive force voltage difference becomes zero from the time of zero crossing in the step is less than the reference time, the rotation speed of the drum motor is judged to be fast and the speed is controlled slowly (S6) while the reference voltage from the time of zero crossing. If the time when the over EMF voltage difference becomes zero is greater than the reference time, it is determined that the rotational speed of the drum motor is slow to control the speed quickly (S6).

As described above, the present invention compares and measures the time at which the counter electromotive force generated from the coil reaches an arbitrary reference voltage and determines the rotational speed of the drum motor according to the result. The structure of the drum motor can be simplified by removing the formed FG pattern.

Claims (1)

In the V-Cal head drum motor which supplies a driving signal to the three-phase coil wound on the stator core in the microcomputer, it is determined whether or not the counter electromotive force generated from the three-phase coil is zero crossing (S1), and zero in the step. In the case of crossing, the step of measuring the voltage of the counter electromotive force (S2), and the step of determining whether the output voltage difference between the reference voltage and the counter electromotive force voltage is 0 (S3), and if it is determined that the difference between the reference voltage and the counter electromotive force voltage is 0 in the step Stopping the voltage measurement of step (S4), and comparing the time when the difference between the reference voltage and the counter electromotive force voltage becomes zero (S5) after the step (S5), and when the measurement time is less than the reference time in the step Slowly controlling the speed of the drum motor (S6), and if the measuring time is faster than the reference time in the step of controlling the speed of the drum motor ( S7) rotational speed measuring method of the BC head drum motor, characterized in that consisting of.