JPH05168295A - Driving circuit for motor - Google Patents

Abstract

PURPOSE:To so control a motor as to effectively stop its rotation at a predetermined position in a driving circuit for the motor to control the stepping motor. CONSTITUTION:A brake controller 6 is driven in response to a stop signal. A transistor Q7 connected between coils L1, L2 and a ground is turned ON by the controller 6 to connect the coils L1, L2 to the ground.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive circuit,
Particularly, it relates to a motor drive circuit for controlling a step motor.

[0002]

2. Description of the Related Art FIG. 3 is a diagram for explaining the structure of a PM type (claw pole type) stepping motor. In the figure, reference numeral 1 denotes a structure in which a cylindrical magnet 1a which is multi-pole magnetized by a rotor is fixed to an output shaft 1b.

Two sets of coils L ₁ and L ₂ wound around yoke portions 2a and 2b are arranged around a cylindrical magnet 1a constituting the rotor 1.

The yoke portions 2a, 2b are two yokes 2a _-1 , provided with tooth poles facing the cylindrical surface of the cylindrical magnet 1a.
2a _-2 and 2b _-1 , 2b _-2 ) are arranged so that the tooth poles mesh with each other with a gap.

The stepping motor has two coils L ₁ ,
By supplying the pulse signal to L ₂ , the rotor 1 rotates by an angle corresponding to the phase of the tooth pole each time the pulse signal is input.

FIG. 4 shows a drive circuit for a step motor.
In the figure, L ₁ and L ₂ indicate two coils of the motor. The coils L ₁ and L ₂ are connected in series, and the series circuit including the coils L ₁ and L ₂ is connected between the terminals T _V φ and T _V φ.

Reference numeral 3 represents a drive circuit. The drive circuit 3 includes a buffer operational amplifier 3a, a non-inverting amplifier circuit 3b, and an inverting amplifier circuit 3c. The non-inverting amplifier circuit 3b is an operational amplifier 3b
_-1 and resistors R _s and R _f , which amplifies the input pulse signal and supplies it to one end of the coil that constitutes the stepping motor. The inverting amplifier circuit 3c is an operational amplifier 3b _-1 and a resistor R _s, made of R _f, inversely amplifies the input pulse signal is supplied to the other end of the coil constituting the stepping motor.

FIG. 5 is a circuit diagram of a conventional non-inverting amplifier circuit.

[0009] The transistors Q ₁ to Q ₇ and resistors R ₁ consists differential amplifier, transistors Q ₈ to Q ₁₇ and resistors R ₂ to R _4, the output circuit is constituted by the capacitor C _1, the base of the transistor Q ₁ Is the non-inverting input terminal, the base of transistor Q ₄ is the inverting input terminal, and contact A
Is the output terminal. Inverting input terminal and output terminal have resistance R
They are connected by _f and a voltage is applied to the inverting input terminal via a resistor R _s . An input pulse signal is input to the non-inverting input terminal.

The power supply voltage Vcc is connected to the stop signal input terminal T _CE via the resistor R ₅ .

The stop signal input terminal T _CE is connected to the bias circuit 4. The bias circuit 4 turns off when the stop signal CE input to the stop signal input terminal T _CE becomes high level, cuts off the bias for driving the operational amplifier, and supplies the regulator 5 for controlling the power cut transistor Q ₁₈ . Cut the bias supply.

When the bias to the regulator 5 is cut off, the transistor Q ₁₈ is turned off, the power supply to the terminal T _VPS is cut off, and the power is not supplied to the output circuit.
Therefore, no current flows into the coils L ₁ and L _{2 of} the stepping motor. Therefore, the motor stops.

The inverting amplifier circuit 3c has substantially the same configuration. In the case of the inverting amplifier circuit 3c, a constant voltage is supplied to the non-inverting input terminal and an input pulse signal is applied to the resistor R to the inverting input terminal.
It is configured to be input via ₅ . Since the drive signal stopping operation from the inverting amplifier circuit 3c is the same as that of the non-inverting amplifier circuit 3b, the description thereof will be omitted.

[0014]

However, in the conventional motor drive circuit for the stepping motor, the motor is stopped by turning off the bias to the operational amplifier. Therefore, the output transistors Q ₁₂ and Q ₁₄ are also turned off, and the output is reduced. The terminals are in an open state (high impedance), a back electromotive force is generated due to the inertia of the motor, and the back electromotive voltage causes the motor to rotate, and there is a problem that it does not stop at a predetermined position. ..

The present invention has been made in view of the above points, and an object thereof is to provide a motor drive circuit capable of controlling a motor so as to surely stop rotation at a predetermined position.

[0016]

According to the present invention, an input pulse signal is supplied to a coil constituting a motor through an amplifier to drive the motor and the bias voltage to the amplifier is turned off. A motor drive circuit for stopping rotation of a motor, comprising a brake circuit for grounding the coil when the motor is stopped and absorbing a counter electromotive voltage generated in the motor.

[0017]

When the motor is stopped, the coil is grounded by the brake circuit according to the stop signal, so that the counter electromotive voltage generated in the motor can be absorbed by the ground and the motor can be braked.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a circuit diagram of a main part of an embodiment of the present invention. In the figure, the same components as those in FIGS. 2 and 3 are designated by the same reference numerals, and the description thereof will be omitted.

A brake control circuit 6 includes PNP transistors Q ₁₉ , Q ₂₂ , Q ₂₃ , NPN transistor Q ₂₀ ,
Q _21, consisting of resistors R ₆ to R _9. When the stop signal CE becomes low (L), first, the transistors Q ₁₉ and Q ₂₀ are turned on.

Transistor Q₁₉, Q₂₀When is turned on,
Langista Q_{twenty one}Base potential of transistor Q_{twenty one}Saturation of
Voltage V_SaTQ20Approximately 0.2 (V), so the transition
Q _{twenty one}Turn off.

Therefore, the transistor Q_{twenty two}, Q_{twenty three}Is off
And transistor Q₁₃, Q₁₄Current I at the base of_CQ23
Does not flow. Therefore, the brake control circuit
Dista Q₁₃, Q₁₄Is not controlled, the braking action is
Not done. Next, the stop signal CE goes high (H).
And Transis Q₁₉, Q₂₀Turns off. Transis Q₁₉，
Q₂₀Turns off, the transistor Q_{twenty one}The base of the resistance
R₈Through I_BQ21= (V_PS-V_BEQ21) / R₈…
(1) is supplied, transistor Q _{twenty one}Turns on.

When the transistor Q ₂₁ is turned on, a current I _CQ22 = (V _PS −V _BEQ22 −) _flows through the collector of the transistor Q _21.
V _CEQ21 ) / R ₉ (2) flows.

[0023] Since the transistor Q _22, Q ₂₃ is that constitute a current mirror circuit, the current I _CQ22 flows to the collector of the transistor Q _22, the same current I _CQ23 and current I _CQ22 the collector of the transistor Q ₂₃ flows , The base current of the transistor Q ₁₄ .

[0024] When the base to the current I _CQ23 of the transistor Q ₁₄ flows through the transistor Q ₁₄ is turned on. Transistor Q
_{When 14} is turned on, the output terminal T _V φ has a voltage Vφ = V _SaTQ14
The impedance is as low as 0.2 V. Therefore, the current due to the back electromotive force of the coil is passed to the ground through the transistor Q ₁₄ and brakes the motor.

The same brake control circuit is also provided in the inverting amplifier circuit 3c connected to the other end of the coil, and the same operation is performed.

[0026] In addition, CE is biased also off at the same time regulator 5 when it comes to high, transistor Q ₁₈ is turned off, V _PS is not supplied by the external capacitor C _PS, V _PS is supplied immediately to the It does not become the GND potential, and as shown in FIG. 2, time t = (C _PS · ΔV _PS ) / ΔI
_PS (3) (I _PS : current consumption during operation) gradually decreases.
Further, according to the equation (2), V _PS −I _BQ21 × R ₈ = V _{BEQ21 ≈0} .
7 to the transistor Q ₂₁ until (V) is supplied base current, transistor Q ₂₁ is in the ON state, it is possible to continue to put a brake on the stepper motor.

[0027] Then the current is not supplied to the _{V PS -I BQ21 × R 8 <} V BEQ21 to become the transistor Q _21, the brake for the OFF state is released.

At the same time as CE = H, both ends of the motor are set to low impedance to set the brake mode, the counter electromotive voltage is absorbed to the ground, and the brake circuit is maintained for a time t (= 170 msec) determined by the impedance of the capacitor and the circuit. After the operation, the circuit turns off naturally and the current consumption at the time of stop can be reduced to 0 μA by the stepping motor to stop (standby).

As described above, when the stepping motor is stopped, the brake can be applied to surely stop the rotational position of the stepping motor at a predetermined position, and after the stop, the brake is naturally released and current is not consumed. ..

[0030]

As described above, according to the present invention, it is possible to brake the motor by making both ends of the motor have a low impedance and significantly reducing the generation of the counter electromotive force.
Further, since the brake can be released by discharging the capacitor, there is no power consumption at the time of stop, and the power consumption can be reduced.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a main part of an embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of the embodiment of the present invention.

FIG. 3 is a configuration diagram of a stepping motor.

FIG. 4 is a circuit diagram of a drive circuit of a stepping motor.

FIG. 5 is a circuit diagram of a main part of a conventional example.

[Explanation of symbols]

L ₁ and L ₂ coil 3 drive circuit 3a buffer amplifier 3b non-inverting amplifier circuit 3c inverting amplifier circuit 6 brake control circuit

Claims (1)

[Claims] 1. The motor is rotated by supplying an input pulse signal to a coil constituting a motor through an amplifier to drive the motor and turning off a bias voltage to the amplifier in response to a stop signal. A motor drive circuit for stopping the motor drive circuit, comprising a brake circuit that grounds the coil according to the stop signal and absorbs a counter electromotive voltage generated in the motor.