JPH0612958B2 - DC motor drive circuit - Google Patents

Description

Description: (a) Technical Field of the Invention The present invention relates to a drive circuit related to DC motor control, which is effective when applied to an input / output terminal device.

(b) Background of technology In a line printer installed in an OA device input / output terminal, a recording paper feeding mechanism is one of the main driving mechanisms. The present invention is
In particular, the present invention is presented for a motor drive source intended to increase the precision and speed of recording paper feeding.

(c) Prior art and problems The target motor is a DC motor driven by an armature control system, especially a dual power supply drive.

Conventionally, such a DC motor is provided with an electronic control circuit including a comparator (circuit element) that freely controls the rotation direction, a transistor that performs rotation activation and speed control, and
Or, generally, reverse rotation control or constant speed control is performed.

In this case, for control, the motor is started or the braking is stopped by the signal input of the microprocessor. Therefore, two power supplies are required for motor control, a main power supply for excitation and a logic power supply for driving the electronic control circuit. Therefore, depending on these initial conditions when the power is turned on, there is a problem in that the reverse rotation may start and the positioning accuracy on the motor load side is likely to collapse. Further, in the case of intermittently feeding the paper, it is difficult to keep the line spacing constant in the DC motor drive.

(d) Object of the Invention The object of the present invention is to solve the above problems. Therefore, the motor is driven at a high speed at a predetermined interval in the forward direction (row direction) of feeding the recording paper.

(e) Configuration of the invention The above-mentioned object is to provide a constant voltage circuit for generating a predetermined voltage from a motor excitation main power source, a drive control circuit having a logic power source for exciting a motor by a motor drive signal, and continuing the motor drive signal. A forward rotation drive circuit that excites the forward rotation of the motor, a differential circuit that detects disconnection of the motor drive signal and performs brake control, and a brake time setting comparator that outputs a predetermined time control signal based on the output of the differential circuit A DC motor drive circuit comprising a brake signal generation circuit including a motor reverse rotation prevention circuit including a resistor and a capacitor inserted on the input reference side of the comparator, and a brake drive circuit operated by the control signal. Can be achieved by

(f) Embodiment of the Invention Hereinafter, the present invention will be described in detail with reference to the DC motor drive circuit diagrams of FIGS. 1 to 3.

FIG. 1 is an overall circuit configuration block diagram. In the figure, 1 is a DC motor to be controlled, 2 is a main power source of the motor, that is, a power source input section, 3 is a logic power source input terminal for drive control of the motor, and 4 is a microprocessor or the like for direct control. This is a signal input terminal. Reference numeral 5 is a constant voltage circuit for adjusting the input voltage from the main power supply 2, 6 is a drive control circuit for exciting the motor drive by the signal input of the terminal 4, 7 is a signal generation circuit for performing brake control by the signal input of the terminal 4, and 8 is It is a brake drive circuit that operates according to a brake signal from the signal generation circuit 7. Reference numeral 9 is a constant voltage power supply circuit 5 of the motor 1 and a forward rotation drive circuit which operates according to the motor drive control circuit signal.

FIG. 2 is a circuit that further embodies the circuit block diagram of the previous figure. The input Vdd of the main power supply 2 is DC12V, DC24
A constant voltage circuit 5 composed of a constant voltage diode ZD ₁ , a resistor R ₁ and a Darlington transistor Tr _{1 which} can easily obtain a predetermined output voltage Vdd ′ according to a motor rating such as voltage is inserted.

Multiple transistors Tr _2, Tr ₃ of cliff output Vdd 'is diagonally become near-motor arranged via outgoing a constant voltage circuit 5 (sash),
Connected to Tr ₄ and Tr ₅ . In Figure 2 circuit, since L ₁ and the output of the L ₂ is not when the other logic power Vcc3 not turned, the bridge connection points b ₁ of the transistor Tr ₂ to Tr ₅
Both b ₂ are lifted by resistors R ₂ and R ₄ , and the motor does not rotate.

In the above state, when the motor signal 10 is input from the signal input terminal 4 of the motor control, that is, the positive logic control pulse 11 of an appropriate time width is input from the microprocessor, the operation is performed in the following order to perform the paper feeding operation.

The input of the control pulse 11 grounds the output line V ₁ of the comparator L ₁ directly connected to the input terminal 4. As a result, the electric potential at the bridge connection point b ₁ side becomes lower than that at the bridge connection point b ₂ side, and the motor 1 starts to rotate in the normal direction. In this case, the pair of transistors Tr ₃ and Tr ₄ connected in a cross-connect operation (the forward rotation drive circuit 9 operates). The resistor R ₂ and the variable resistor R ₃ are dividing resistors with respect to the stabilizing voltage Vdd ′. At the same time, the control pulse 11 is also introduced to the brake signal generation circuit 7 side that performs brake control. The inversion control pulse 12 is input to the brake side circuit 7 via the inverter IC ₁ connected to the input terminal 4. The brake control pulse 12 is composed of a brake signal generator by an input differentiating circuit of the circuit 7 and a comparator L ₂ which compares the generated brake signal with a reference voltage and outputs a brake drive pulse.

The capacitor C ₂ and the diode D ₁ and the diodes D ₂ and R ₁₀ form a pair of the control pulses 12 connected in cascade.
Is a differentiating circuit.

Here, the edge on the stop side of the motor signal is detected and shaped into a differential waveform, which makes it possible to set an arbitrary braking time by the comparator in the next stage.

The resistor R ₉ and the capacitor C ₃ are a compensating resistor on the input side of the comparator L ₂ and a noise absorbing capacitor. The variable resistor R ₈ on the other input side of L _{2 is} a reference voltage adjusting resistor that divides the Vcc logic power supply voltage. Furthermore, the capacitor C ₄
And the resistor R ₇ are inserted to prevent reverse rotation of the motor when the logic power supply Vcc is turned on. When the power is turned on, the voltage between the terminals of the capacitor C ₄ is almost 0 V, and reaches a stable voltage after a time determined by the time constant of the capacitor C ₄ and the resistor R ₇ . First, set the voltage across the capacitor C ₄ to 0.
If V is set, + of comparator L ₂ at power-on
The input on the polarity side momentarily becomes Vcc, and the input signal (4) becomes "Lo".
It becomes possible for the comparator L _{2 to} ignore the positive pulse signal generated through the inverter IC ₁ at the time of w ″. The brake signal generated by the input signal (4) during the stable operation is the positive pulse. Although the signal is in phase with the signal, as described above, the capacitor C ₄
Since the pulse signal when the power is turned on can be ignored by the circuit including the resistor R ₇ and the resistor R ₇ , the reverse rotation of the motor can be prevented.

The brake signal generator 7 for controlling the motor detects the rising edge 13 of the control pulse 12 with a differentiating circuit and outputs it to L
₂ and a control pulse having an appropriate time width is output to the output side of the comparator L ₂ . That is, the potential of the bridge connection point b ₂ is divided by the dividing resistors R ₄ and R ₄ due to the grounding of the output line V ₂ of the L _2.
It drops to divided voltage of ₅ more determined power Vdd ', the motor braking allowed operation and a set of the transistors Tr ₂ and Tr ₅ of cliff the sash (brake driving circuit 8 of FIG. 1) is performed. The capacitor C ₁ inserted in parallel with the motor 1 is an external surge absorbing capacitor.

FIG. 3 is a circuit diagram showing another modification of the motor drive circuit. The circuit diagram basically has the same configuration as in FIGS. 1 and 2.

That is, the configuration itself of the transistor Tr _2, or system circuitry for cross-coupled arrangement of Tr ₅ or the brake signal generating circuit 8, for the control target motor 1 constituting the forward drive and brake drive is the same as Figure 2.

However, for example, in order to improve the motor start-up start-up property during normal rotation driving, a transistor Tr ₆ is inserted on the output stage side of the drive control circuit 6 that performs motor drive excitation, and a transistor Tr ₈ is also inserted on the Vdd ′ side. This improves the motor startability and adds stability to the crossing transistor circuit.

(g) Effects of the Invention According to the DC motor drive circuit of the present invention described above,
The erroneous rotation at the time of turning on the power, which has been a problem in the related art, is eliminated, the positioning accuracy with respect to the printer paper is maintained high, and the forward feed is performed extremely quickly.

[Brief description of drawings]

FIG. 1 is an overall block diagram of a motor drive circuit according to the present invention, and FIGS. 2 and 3 are circuit diagrams of the embodiment of FIG. In the figure, 1 is a DC motor, 2 is a main power supply, 3 is a logic power supply input terminal, 4 is a motor signal input terminal, 5 is a constant voltage circuit,
6 is a drive control circuit, 7 is a brake signal generation circuit, 8 is a brake drive circuit, and 9 is a normal rotation drive circuit.

Claims (1)

[Claims] 1. A constant voltage circuit for generating a predetermined voltage from a main power source for motor excitation, a drive control circuit having a logic power source for exciting a motor by a motor drive signal, and a positive rotation excitation of a motor while the motor drive signal continues. Eggplant forward rotation drive circuit,
A differential circuit that detects a disconnection of the motor drive signal and performs brake control, a brake time setting comparator that outputs a control signal for a predetermined time based on the output of the differential circuit, a resistor inserted on the input reference side of the comparator, A DC motor drive circuit comprising: a brake signal generation circuit including a motor reverse rotation prevention circuit including a capacitor; and a brake drive circuit that operates according to the control signal.