JPH0125319B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive control circuit for a DC motor, and the steady rotation of the DC motor is controlled by supplying a control signal to two Darlington-connected transistors through resistors each having a different resistance value. An object of the present invention is to provide a drive control circuit for a DC motor that does not consume unnecessary power.

Generally, a DC motor requires a large current when starting, and is driven with a small current during steady rotation.

A conventional drive control circuit for controlling starting and stopping of a DC motor is shown in FIG. 1A. In the figure, one end of a DC motor 1 is supplied with positive power from an input terminal 2, and the other end is connected to the collector of an NPN transistor _Tr1 . The emitter of the transistor Tr ₁ is grounded, and the base is connected to the input terminal 3 via the resistor R _1. When a high-level control signal is supplied from the input terminal 3, the transistor Tr ₁ becomes conductive and the signal is input from the input terminal 2. The current flows through the DC motor 1 to ground, causing the DC motor 1 to rotate. Since the current flowing through the DC motor 1 requires a large current at the time of starting, the current supplied from the input terminal 3 to the base of the transistor _Tr1 must always be large enough to flow the large current at the time of starting to the DC motor 1. Therefore, during steady rotation of the DC motor 1, the large current required at the time of starting is not required, and a wasteful current flows through the resistor _R1.This is especially true when the DC motor 1 is used in portable tape recorders, video tape recorders, etc. The disadvantage is that the power consumption becomes large when the

Furthermore, conventionally, there is a drive control circuit using Darlington-connected transistors Tr ₂ and Tr ₃ as shown in FIG. 1B, in which the control signal supplied from the input terminal 3 is made to have a small current. However, in order to make the transistor Tr ₃ conductive in order to rotate the DC motor 1 in this circuit, a voltage of approximately 0.7 V or more is required between the base and emitter of the transistor Tr ₃ , and a voltage of approximately 0.7 V or more is required between the collector and emitter of the transistor Tr ₃ . The voltage was approximately 0.7V, and the disadvantage was that electric current was wasted due to the current flowing there.

The present invention eliminates the above-mentioned drawbacks, and one embodiment thereof will be described with reference to FIG. 2 and the following figures. In this figure, the same parts as in FIGS. 1A and 1B are given the same reference numerals. In Figure 2, 1 is a DC motor, one end of which is connected to input terminal 2 and supplied with positive power.
The other end is connected to the NPN type first transistor Tr ₄ and
It is connected to the collector of the second NPN transistor _Tr5 . The base of the first transistor Tr ₄ is connected to the input terminal _{3 via the first resistor R 3} , and the emitter of the first transistor Tr 4 is connected to the input terminal 3 through the first resistor R ₃ .
It is connected to the input terminal 3 via the resistor R ₄ and also to the base of the second transistor Tr ₅ , and the emitter of the second transistor Tr ₅ is grounded.

When a high level control signal is supplied from the input terminal 3 of the first transistor circuit shown in FIG.
The current flows through the resistor _R4 as the base current of the second transistor _Tr5 , making the second transistor _Tr5 conductive. When the DC motor 1 starts, a large current larger than the collector current of the second transistor Tr ₅ corresponding to the base current flows through the DC motor 1, so the second transistor Tr ₅ acts as a resistor and the collector of the transistor Tr ₅ , Abbreviation for emitter voltage
The voltage exceeds 0.7V and the first transistor Tr ₄ becomes conductive.
The emitter current of the first transistor Tr ₄ is supplied to the base of the second transistor Tr ₅ and the second
A large current necessary for starting the DC motor 1 flows from the collector of the transistor Tr ₅ to the emitter.

When the DC motor 1 performs steady rotation, the current flowing through the DC motor 1 is resisted by the second transistor _Tr5 .
The collector current of the second transistor Tr ₅ corresponding to the base current supplied from R ₄ decreases to the same extent as the collector current of the second transistor Tr ₅ , and the voltage between the collector and emitter of the second transistor Tr 5 becomes approximately 0V, and the first transistor Tr ₄ It becomes non-conductive.

In this way, in the circuit shown in FIG. 2, the control signal supplied from the input terminal 3 directs the current flowing through the DC motor 1 during steady rotation to the second transistor Tr ₅
A transistor with enough current to flow as the collector current of
The base current of Tr ₅ may be sufficient, and at this time, the voltage between the collector and emitter of the second transistor Tr ₅ is approximately 0V, and there is almost no power consumption here. Also, when starting the DC motor 1, the second
The voltage between the collector and emitter of the first transistor Tr ₅ temporarily becomes approximately 0.7V, and the voltage between the collector and emitter of the first transistor Tr ₄ becomes approximately 0.7V.
conducts and the collector of the second transistor Tr ₅ ,
A large current is passed between the emitters.

The second transistor circuit shown in Figure 3 is a PNP
It is composed of a third type transistor Tr ₆ and a fourth PNP type transistor Tr ₇ . The above third transistor Tr ₆ and the fourth transistor
Tr ₇ corresponds to the first transistor Tr ₄ and the second transistor Tr ₅ , respectively, and the third resistor R ₅ and the fourth resistor R ₆
correspond to the first resistor R ₃ and the second resistor R ₄ , respectively, and the control signal supplied to the input terminal 4 has an equal negative absolute value to the control signal of the input terminal 3 shown in the second diagram. It is polar. The circuit shown in Fig. 3 is
The circuit operates in the same way as the illustrated circuit, and its explanation will be omitted.

The circuit of the present invention shown in FIG. 4 is constructed using first and second transistor circuits. In Fig. 4, positive and negative control signals are supplied to input terminals 3 and 4, respectively, and a current I is caused to flow through DC motor 1 to rotate it in the forward direction (or reverse direction). Alternatively, positive and negative control signals may be supplied respectively to cause current I' to flow through the DC motor 1 to rotate it in the reverse direction (or forward direction). Here, for example, when the DC motor 1 is being rotated by supplying positive and negative control signals to the input terminals 3 and 4, respectively, the supply of the negative control signal from the input terminal 4 is stopped and the input terminal 3' It is possible to apply an electromagnetic brake to the DC motor 1 by supplying a positive control signal to the DC motor 1. However, in this case, the transistors Tr ₅ and Tr ₆ are not simply connected by Darlington, so the voltage between the collector and emitter of the transistor Tr ₅ is 0.7V. Therefore, the electromagnetic brake can be sufficiently applied until the DC motor 1 stops, and the DC motor 1 can be stopped quickly.

As described above, the drive control circuit for a DC motor according to the present invention includes first and second motors connected to each other in Darlington.
resistance values of an NPN transistor, a first resistor connected to the base of the first transistor, and a first resistor connected to the connection point between the emitter of the first transistor and the base of the second transistor. a second resistor having a sufficiently smaller resistance value;
and an input terminal for supplying a control signal to the second resistor, a first transistor circuit is provided between the first power source and one end and the other end of the DC motor, respectively;
Darlington-connected third and fourth PNP transistors, a third resistor connected to the base of the third transistor, and a connection point between the emitter of the third transistor and the base of the fourth transistor. a fourth resistor having a resistance value sufficiently smaller than the resistance value of the third resistor, and the third and fourth resistors.
A second transistor circuit having an input terminal for supplying a control signal to the resistor is provided between a second power source having a higher potential than the first power source and one end and the other end of the DC motor. By supplying control signals to the respective input terminals of the first transistor circuit at one end and the second transistor circuit at the other end or one end, the first to fourth transistors are made conductive to start the DC motor and maintain steady rotation. In this case, in order to drive and control the DC motor by making only the second and fourth transistors conductive, a very small base current corresponding to the current flowing from the collector to the emitter of the second and fourth transistors during steady rotation is used as a control signal. In addition, during steady rotation, the voltage between the collector and emitter of the second and fourth transistors is approximately 0V, so no unnecessary power is consumed.
Furthermore, even when an electromagnetic brake is applied to the DC motor to stop it, the electromagnetic brake can be applied sufficiently until the DC motor stops.

[Brief explanation of drawings]

1A and 1B are circuit diagrams of a first example and a second example of a conventional DC motor drive control circuit, FIGS. 2 and 3 are circuit diagrams of each part of the circuit of the present invention, and FIG. 1 is a circuit diagram of one embodiment of the inventive circuit; FIG. 1...DC motor, 2, 3, 3', 4, 4'...
Input terminal, Tr ₁ to Tr ₇ ...Transistor, R ₁ to _{R 6}
……resistance.

Claims (1)

[Claims] 1 Darlington connected first and second
an NPN transistor; a first resistor connected to the base of the first transistor; and a first resistor connected to a connection point between the emitter of the first transistor and the base of the second transistor. A first transistor circuit is connected to a first power source and a DC motor, and includes a second resistor having a resistance value sufficiently smaller than the resistance value of The third and fourth terminals are provided between one end and the other end, and are connected to each other by Darlington.
a PNP transistor, a third resistor connected to the base of the third transistor, and a third resistor connected to the connection point between the emitter of the third transistor and the base of the fourth transistor. A second transistor circuit including a fourth resistor having a resistance value sufficiently smaller than the resistance value of the resistor and an input terminal for supplying a control signal to the third and fourth resistors is connected to a voltage higher than the first power supply. Provided between a second potential power source and one end and the other end of the DC motor, and input terminals of the first transistor circuit at the one end or the other end and the second transistor circuit at the other end or the one end, respectively. By supplying a control signal, the first to fourth
A drive control circuit for a DC motor, characterized in that the DC motor is started by turning on a transistor, and when steady rotation is achieved, only the second and fourth transistors are turned on to drive and control the DC motor.