JPH03215148A - Motor rotation direction detection device - Google Patents

Abstract

PURPOSE:To simplify the constitution by providing a means for generating a signal, whose waveform differs according to the rotational direction of a motor, so as to judge the rotational direction from the difference of the waveform. CONSTITUTION:A speed control signal is supplied to a driving circuit 2 from an input terminal 3, and a motor 1 rotates at an optional speed. A magnetizing pattern, whose intensity changes cyclically, is provided at the periphery of the rotary part of the motor 1, and a rotation signal generator 4 detects the magnetic flux by this magnetizing pattern so as to get a rotation signal. The rotation signal is supplied to the differentiation circuit 6 consisting of a capacitor 7 and a resistance 8, to get a straight polarity pulse at the point of time of steep rise of waveform at an output terminal 9. When the motor 1 rotates reversely, a negative polarity pulse is gotten.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotational direction detection device for a motor used as a capstan motor of a VTR (video tape recorder) or the like.

[Conventional technology]

Slow-motion playback on a VTR is performed by scanning each track on a magnetic tape multiple times. One method of slow-motion playback is to advance the magnetic tape intermittently one track pitch at a time, and play back at each track. A method called so-called fine-slow reproduction is known in which the head is kept in a good tracking state and the reproduction scan is performed multiple times. In this system, the magnetic tape is fed through a series of operations of acceleration, constant speed, and deceleration, and when the magnetic tape is stopped due to the deceleration operation, the playback head converts the 1-lanone on the magnetic tape into a good tranokink. Make the playback scan in the state.

By the way, in this series of operations of the J-reservoir of the magnetic tape, the deceleration of the magnetic tape is caused by the capstan motor
This is done by supplying a drive signal in the f-turn direction, but it is desirable to cut off the supply of this drive signal in the reverse direction when the magnetic tape stops due to deceleration. If the supply period of this drive signal is too short, the deceleration effect will disappear before the magnetic tape stops, causing the magnetic tape to move further in the feeding direction.If the supply period of the drive signal is too long, the magnetic tape will It passes through the stopped state and moves in the opposite direction to the feeding direction. As a result, even if the playback head is designed to playback scanning from 1-ranok in a good tracking state when the magnetic tape stops, the playback head will play back the tracking in a good tracking state. It will be scanned.

For this purpose, the period for supplying the urging signal in the reverse direction is set to VT
It is necessary to adjust each R with high precision, which is very time-consuming.

On the other hand, when decelerating the magnetic tape by supplying a driving signal in the reverse direction to the capstan motor, if this driving signal continues to be supplied, the magnetic tape will stop and then start running in the opposite direction. . Therefore, if the rotation direction of the capstan motor is detected and the supply of the drive signal in the reverse direction to the capstan motor is cut off at the moment when the rotation direction of the capstan motor is reversed when the magnetic tape is decelerated, the magnetic tape can be decelerated. The tape will stop accurately.

The method of detecting the rotation direction of the capstan motor is rNαt.
ional2 Technicafl Report
tJ Vow. 28 No. 3 (, June, 1982
)PP. It is described in the "4.4 Capstan Motor Brake" column of 36-37. This is because the capstan motor is equipped with two FGs (frequency generators), and these FGs
The phase difference of the signals is made to vary depending on the rotational direction of the capstan motor. That is, if the phase relationship between the two FG signals is set so that when the capstan motor is rotating in the normal direction, the phase of the second FG signal is shifted by 90 degrees with respect to the first FG signal, then when the capstan motor is rotating in the normal direction, the phase of the second FG signal will be shifted by 90 degrees. The second FG signal has a phase shift of 180° with respect to the first FG signal, and by sampling the level of the other at the rising edge or falling edge of one of these first and second FG signals, Different levels of detection signals are obtained when the capstan motor rotates forward and reverse.

[Problem to be solved by the invention]

However, in the above conventional technology, two FGs are required, and along with this, a sampling circuit consisting of a processing circuit such as a dedicated amplifier and a flip-flop circuit for detecting the rotation direction is also required. , the number of means and circuits added for detecting the rotational direction of the capstan motor increases significantly, resulting in an increase in scale and an increase in the cost of the VTR.

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and provide a motor rotation direction detection device with a simple configuration.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a first means for generating a signal having a different waveform depending on the rotational direction of the motor;
A second means is configured to detect the waveform of the signal and determine the rotation direction of the motor.

[Effect]

When the motor rotates, a signal is output from the first means, and the waveform of this signal varies depending on the rotational direction of the motor. An example of such a signal is a sawtooth wave, which repeats a waveform in which the level gradually rises and then rapidly drops when the motor rotates in the forward direction.When the motor rotates in the reverse direction, the level suddenly decreases. The waveform rises and then gradually falls.

Such a difference in waveforms is detected by a second means,
The direction of rotation of the motor is determined. When the above-mentioned sawtooth wave signal is output from the first means, by using a differentiation circuit as the second means, when the motor rotates in the normal rotation direction, a sudden and drastic change in Le/Lucani is caused. When the motor moves in the reverse direction, a negative pulse is obtained, and when the motor moves in the reverse direction, a positive pulse or 'I'f 'i . It will be k. Depending on the polarity of this pulse, it is possible to determine the four-way rotation direction of the motor.

[P::Jj”ti fノj]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the motor rotation direction detection device according to the present invention, in which 1 is the motor, 2 is the north moving concave path, 3 is the input terminal for the speed control signal, and 1 is the rotation A signal generator, 5 an amplifier, 6 a differential concave path, 7 a capacitor, 8 a resistor, and 9 an output terminal.

In the figure, a speed/reverse control signal is supplied from the input terminal T3 to the motion circuit 2, and in response to this, the motor rotates in either forward or reverse direction at an arbitrary speed. A magnetic flux whose strength changes periodically is provided around the rotating part of the motor 1, and the rotation signal generator 4 detects the magnetic flux generated by this 2j magnetic pattern, thereby controlling the rotation of the motor 1. A rotation signal whose level changes at a period inversely proportional to the rotation speed is obtained.

Here, is the circumference of the rotating part of motor 1 divided into equal intervals? In each section, as shown in Figure 2, the S magnetic poles are arranged so that the strength gradually decreases to SL+52, and after passing through the non-magnetized part of O, the magnetic poles are arranged as N,, N3, N2, N, and so on. N magnetic poles are arranged with gradually increasing strength.

When the rotational signal generator 4 detects such a magnetization pattern in the direction of arrow A, it rises sharply as shown in FIG. S (occurs at the boundary with the magnetic pole), a sawtooth wave-like rotation signal whose level gradually decreases is obtained.

After the rotation signal is amplified by an amplifier 5, it is supplied to a differentiating circuit 6 consisting of a capacitor 7 and a resistor 8. Therefore, at the output terminal 9, as shown in FIG. 3(C),
A pulse of positive polarity is obtained at the steep rise of the waveform shown in FIG. 3 (α).

On the other hand, the speed control signal from input terminal 3 causes motor 1 to
When rotates in the opposite direction to the above, the rotation signal generator 4 detects the magnetization pattern shown in FIG. 2 in the direction of arrow B, and the level gradually increases as shown in FIG. 3(b). After that, the rotation signal falls sharply (this fall occurs at the boundary between the S and N1 magnetic poles of the second layer 1), and a sawtooth rotation signal is obtained. The waveform of this rotation signal is different from the rotation signal shown in FIG.
As shown in fi(d), a pulse of negative polarity is obtained at each point in time when the waveform of FIG. 3(b) steeply falls.

In this way, rotation signals with different waveforms are obtained depending on the rotational direction of the motor 1.
The rotation direction of the motor 1 can be determined by being detected as pulses of different polarities.

The rotation signal generator 4 includes a magnetoresistive element, a Hall element,
It is possible to use a magnetic flux sensing element with a magnetic field. However, when using magnetism, changes in magnetic flux are detected, so the pulses shown in Figure 3 (C) and (d) can be obtained directly by detecting the magnetization pattern, and the differential circuit 6 can be omitted.

Although the embodiments of the present invention have been described above, the present invention is not limited only to these embodiments.

For example, in the above embodiment, a sawtooth wave-like rotation signal is generated, but the waveform may be made up of a part where the level changes stepwise and a part where the level changes sharply, or one N Any waveform can be used as long as the waveform of the rotation signal generated depending on the rotational direction of the motor 1 is generated by forming a pair of S magnetic poles and arranging a plurality of pairs around the rotating part of the motor 1, etc. rotation signals can be used. Needless to say, a means for detecting the difference in waveform of the rotation signal is provided accordingly.

〔Effect of the invention〕

As described above, according to the present invention, the rotational direction of the motor can be detected with a small number of parts and a simple configuration, which greatly improves reliability and improves economic efficiency.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a motor rotation direction detecting device according to the present invention, FIG. 2 is a diagram showing an example of a magnetization pattern around the rotating part of the motor in FIG. 1, and FIG. FIG. 1 is a leak diagram showing signals of each part in FIG. 1; 1 motor, 4 rotation signal generator, 6 differentiation circuit.纂Z 3rd V (d) ]]]]]]

Claims (1)

[Claims] 1. A rotational direction detection device for a motor capable of rotating in forward and reverse directions, which includes means for generating a signal having a different waveform depending on the rotational direction of the motor as the motor rotates. A motor rotation direction detection device characterized in that the rotation direction of the motor can be determined from a difference in waveform of the signal. 2. In claim 1, the means is a rotating member that rotates integrally with the motor and has an outer circumferential surface divided at equal intervals and provided with a magnetization pattern such that the polarity strength increases in the same direction for each division. and a magnetic flux detection element that detects magnetic flux from the magnetized pattern. 3. The rotational direction detection device for a motor according to claim 2, wherein each of the sections is formed by sequentially arranging an N-pole magnetized section, a non-magnetized section, and an S-pole magnetized section. 4. A motor rotation direction detecting device according to claim 2 or 3, wherein the output signal of the means is supplied to a differentiating circuit.