JPS637196A - Pulse motor driving circuit - Google Patents

Abstract

PURPOSE:To obtain a sufficient driving current even when a pulse motor is driven at a high speed by forming a path of a current due to an induced power generated in a coil. CONSTITUTION:When a transistor 2 is turned from ON to OFF, a voltage V1 is generated in a first coil 4. A voltage V2 is generated in a second coil 5 by means of electromagnetic induction between the first and second coils 4 and 5. In order to rapidly drop the voltage V2, a transistor 11 is turned ON immediately after the transistor 2 is turned OFF to feed a current in the path of the coil 5, a resistor 12, the transistor 11, a diode 8 and the coil 5 to drop a voltage. Thus, the starting of a driving current fed to a pulse motor can be accelerated.

Description

[Detailed description of the invention] Technical field The present invention relates to a pulse motor drive circuit.

Conventional technology An example of a conventional pulse motor drive circuit is shown in FIG.

This circuit, after the second transistor 2 is turned off,
When the first and third transistors 1 and 3 are turned on to cause current I2 to flow through the second coil 5 of the pulse motor, the electromagnetic induction of the first coil 4 of the pulse motor causes the current I2 to flow through the second coil 5. Voltage ■2 is generated and the second coil 5
It is possible to prevent the current I2 from flowing to the current I2. For this purpose, the first and third diodes 6 and 8 are connected in parallel with the first and second transistors 1 and 3, respectively, and the voltage is consumed by the resistance valve of the coil of the pulse motor and the internal resistance of 119. was lowering.

In this conventional pulse motor drive circuit, this voltage V2 is consumed through the first and third diodes 6 and 8 and the power supply 9, so that the power supply voltage E
Since this flow is suppressed, the voltage ■2 applied to the second coil 5 does not drop suddenly, and the start of the current 1□ is delayed.

This is a drawback in that a sufficient drive current cannot be obtained, especially when driving a pulse motor at high speed.

OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to provide a pulse motor drive circuit that can obtain a sufficient drive current even when driving a pulse motor at high speed.

Composition of the Invention According to the present invention, there is provided a pulse generating means that starts at the trailing edge of a drive pulse signal and outputs a pulse shorter than the drive pulse width; A pulse motor drive circuit characterized in that it has a current path control means for forming a path for electric current.

Next, the present invention will be explained in more detail with reference to the drawings showing one embodiment of the present invention.

Referring to FIG. 1, the pulse motor drive circuit of one embodiment of the present invention further outputs a pulse that starts at the trailing edge of the drive pulse signal and is shorter than the drive pulse width in the drive circuit shown in FIG. monostable multivibrator 10,
A fourth transistor 11 that is turned on/off by this monostable multivibrator 10 and this transistor 1
A circuit having a resistor 12 connected in series with the resistor 1 is provided. Note that this circuit is shown for one phase of the pulse motor.

Next, the operation of this embodiment will be explained with reference to FIG. When the common signal a and the drive signal S are both high level and the first and second transistors 1 and 2 are on, when the drive signal S is set low level and the second transistor 2 is turned off, the first coil 4, voltage ■1 is generated. FIG. 2 shows a time chart from the time when this voltage (1) is generated. Due to electromagnetic induction between the first and second coils 4 and 5, the second coil 5
A voltage V2 is generated. While this voltage (2) is higher than the power supply voltage E, no current flows through the second coil 5, so in order to quickly drop the voltage (2), the fourth transistor 11 is turned off immediately after the second transistor 2 is turned off. In other words, the trailing edge of the drive signal triggers the monostable multivibrator 10 to obtain the output signal d (■4), and this signal d turns on the fourth transistor 11, causing the second Current flows through the path of coil 5 → resistor 12 → fourth transistor 11 → third diode 8 → second coil 5, and the voltage is dropped. In this way, as shown in FIG. 2, the start of the drive current flowing through the pulse motor can be made faster.

In FIG. 2, the dotted line waveform of the current I2 is the current waveform of the conventional circuit shown in FIG.

As described in detail, the pulse motor drive circuit according to the present invention includes a pulse generating means such as a monostable multivibrator that starts at the trailing edge of a drive pulse signal and outputs a pulse shorter than the drive pulse width; By providing a current path control means that forms a path for current caused by the induced power generated in the coil of the motor only during the existence period of this short pulse output, the drive flowing through the pulse motor is increased. This has the effect of making it possible to speed up the start of the current flow, thereby increasing the motor torque.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the present invention, FIG. 2 is an operation timing diagram thereof, and FIG. 3 is a circuit diagram of a conventional pulse motor drive circuit. Explanation of symbols of main parts 1.2.3...Transistor 4.5...Coil 6.7.8...Diode 10...Monostable multi Vibrator 11...
... Transistor 12 ... Resistor

Claims (1)

[Claims] A pulse generating means that starts at the trailing edge of a driving pulse signal and outputs a pulse shorter than the driving pulse width, and a current that forms a current path due to the induced electromotive force generated in the coil of the motor during the existence of the output pulse of the pulse generating means. What is claimed is: 1. A pulse motor drive circuit comprising: road control means.