JPH06121580A - Number of revolution controller for motor - Google Patents

Abstract

PURPOSE:To start a motor positively by widening the range of output current to the motor with respect to the control current. CONSTITUTION:A current control transistor Tr1 is connected in series between a power supply E and a motor M and the output current I to the motor M is controlled by controlling the base current IB1 of the current control transistor Tr1. Two transistors Tr2, Tr3 are connected in parallel between the base of the transistor Tr1 and the negative pole of the power supply E and collector currents IB2, IB3 of the transistors Tr2, Tr3 are controlled by a control circuit l depending on the driving voltage of the motor M. Base current IB1 of the transistor Tr1 is shared by the collector currents IB2, IB3 of the transistors Tr2, Tr3 thus widening the range of the output current I with respect to the control current Is fed from the control circuit 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor rotation speed control circuit for controlling an output current to a motor according to a driving voltage of the motor to control a rotation speed of the motor.

[0002]

2. Description of the Related Art Conventionally, the rotation speed control of a DC motor is performed when the rotation speed is kept constant in accordance with the load or when the drive voltage corresponding to the rotation speed change instruction is supplied. Is used.

FIG. 11 is a diagram showing a circuit for controlling the rotation speed of the DC motor. In the conventional DC motor, a transistor Tr1 is connected in series between the power source E and the motor M, and the output current to the motor M is controlled by the transistor Tr1. A transistor Tr2 is provided between the base of the transistor Tr1 and the negative electrode of the power source E, and the base current I _B2 of the transistor Tr2 is controlled by the control circuit 1 according to the drive voltage of the motor M.

When the current amplification factor of the transistor Tr1 is h _FE1 and the base current is I _B1 , the collector current, that is, the output current I to the motor M becomes h _FE1 · I _B1 , and the base current I _B1 is controlled. The output current I is controlled by. On the other hand, the current amplification factor of the transistor Tr2 is h _FE2 , and the base current (control current from the control circuit 1) is I _S.
Then, since the collector current of the transistor Tr2 becomes the base current I _B1 of the transistor Tr1, the output current I becomes h _FE1 · h _FE2 · I _S. Therefore, the output current I to the motor M is controlled by controlling the base current I _S of the transistor Tr2.

By the way, the DC motor is generally shown in FIG.
The start-up output current is several times larger than the output current during rotation. For this reason, when the power switch SW is turned on, the control circuit 1 causes the motor M to output a starting current that is several times the load current, and starts the motor M. After the start, the output current I becomes the load current. Limit the number of rotations of the motor M to a required value.

FIG. 13 is a diagram showing another circuit for controlling the rotation of a conventional DC motor. In FIG. 11, a transistor T3 is provided between the transistor Tr1 and the transistor Tr2 in FIG. 11 to increase the amplification degree of the base current I _B1 of the transistor Tr1. That is, the transistors Tr2 and Tr3 are Darlington-connected, and the current amplification factors of the transistors Tr2 and Tr3 are h _FE2 and h _FE3 , respectively.
A current _{obtained by} multiplying the base current I _S of the transistor Tr2 by h _{F E2} · h _FE3 becomes the base current I _{B1 of the} transistor Tr1. Therefore, the output current I becomes h _FE1 · h _FE2 · h _FE3 · I _S , which makes it possible to supply a large output current I as compared with the circuit shown in FIG. 11.

[0007]

The former one of the conventional DC motor rotation speed control circuits is a transistor Tr1.
Of the base current I _B1 of the transistor Tr2 is the current amplification factor h of the transistor Tr2.
_Since it is limited by _FE2 , when the load is large, when the power switch SW is turned on, the necessary starting current cannot be supplied to the motor M, and the motor M may not start.

On the other hand, the latter one of the conventional DC motor rotation speed control circuits has a larger output current I than the former one.
Therefore, the motor M can be started even when the load is large, but since the fluctuation of the drive voltage of the motor M with respect to the control current I _S output from the control circuit 1 to the base of the transistor Tr2 becomes large, after the start. However, there is a problem that it becomes difficult to control the driving voltage of the motor M to be constant.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a motor rotation speed control circuit which is excellent in motor starting characteristics and can perform stable rotation speed control.

[0010]

The invention according to claim 1 is
In a motor rotation speed control circuit in which a current control transistor is connected in series between a power source and a motor, and the output current to the motor is controlled by controlling the base current of the current control transistor, the base of the current control transistor and the power source. Two drive control transistors which are connected in parallel between the negative electrodes of the two and control the drive of the current control transistors, and a control circuit which controls the base currents of the two drive control transistors according to the drive voltage of the motor. Be prepared.

According to a second aspect of the present invention, a current control transistor connected in series between the power supply and the motor to control an output current to the motor, and a base between the current control transistor and a negative electrode of the power supply are interposed. A drive control transistor for controlling the drive of the current control transistor, and a control circuit for controlling the base current of the drive control transistor according to the drive voltage of the motor. A resistor is connected in parallel to the control transistor.

According to a third aspect of the invention, a current control transistor is connected in series between the power supply and the motor, and the base current of the current control transistor is controlled to control the output current to the motor. In the control circuit, a capacitor is connected between the positive electrode of the power source and the base of the current control transistor.

The invention according to claim 4 comprises a current control transistor connected in series between the power supply and the motor, and a control circuit for controlling the base current of the current control transistor according to the drive voltage of the motor. In the motor rotation speed control circuit, the control circuit has a timer and increases the base current of the current control transistor to a preset current value for a predetermined time after starting.

The control circuit preferably has a detection circuit for detecting the drive voltage of the motor, and releases the increase control of the base current of the current control transistor in response to the detection by the detection circuit. (Claim 5).

[0015]

According to the DC motor of the first aspect, a part of the control current output from the control circuit is input to the base of one drive control transistor, and the rest is input to the base of the other drive control transistor. . Collector currents corresponding to the input base currents flow through the collectors of the double-acting control transistors, and the sum of these collector currents flows through the bases of the current control transistors. Then, a current obtained by amplifying this base current by the current amplification factor of the current control transistor is output to the motor. Since the base current of the current control transistor is shared by the collector currents of the two drive control transistors, the control range of the output current from the current control transistor with respect to the control signal of the control circuit becomes large.

According to another aspect of the DC motor of the present invention, the base current of the current control transistor is the sum of the current flowing through the resistor and the collector current of the drive control transistor.
As the base current of the current control transistor increases by the amount of current flowing through the resistor, the output current from the current control transistor increases and the control range of the output current for the control signal of the control circuit increases.

According to the third aspect of the present invention, when the power switch is turned on, a charging current flows through the capacitor, and a control current (base current) for controlling the current control transistor is supplied until the charging of the capacitor is completed. Current)
Increases by the charging current. The charging current may be supplied directly to the base of the current control transistor, and a drive control transistor is provided between the base of the current control transistor and the negative electrode of the power source to control the drive of the current control transistor. You may make it flow to the base of. As a result, when starting the motor,
The control range of the output current with respect to the control current is increased.

According to another aspect of the DC motor of the present invention, when the power switch is turned on, the control circuit increases the base current of the current control transistor to a preset large current value and starts measuring a predetermined time. To do. Then, after a lapse of a predetermined time, the base current of the current control transistor is controlled to a value according to the drive voltage of the motor.
As a result, the output current of the current control transistor increases for a certain period of time when the motor is started, and the motor is reliably started.

According to the DC motor of the fifth aspect, when the power switch is turned on, the control circuit increases the base current of the current control transistor to a preset current value and starts counting for a predetermined time. . If the drive voltage of the motor rises above a preset starting voltage before the elapse of a predetermined time, the base current of the current control transistor is controlled to a value according to the drive voltage of the motor. As a result, when the motor is started, the output current of the current control transistor increases and the motor is started reliably, and after the motor is started, the output current is limited to an appropriate output current according to the load.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing the configuration of a motor rotation speed control circuit according to the present invention. In the figure, E is a power supply and SW
Is a power switch and M is a motor. Further, Tr1 is a pnp type transistor for controlling the output current to the motor M, and is connected in series between the power switch SW and the motor M. Further, Tr2 and Tr3 are npn-type transistors that control the base current I _B1 of the transistor Tr1 and are connected in parallel between the base of the transistor Tr1 and the negative electrode of the power source E. Reference numeral 1 is a control circuit for controlling the collector current of the transistor Tr1, that is, the output current I to the motor M via the transistors Tr2 and Tr3. The control circuit 1 is
The motor M is connected in parallel and the drive voltage of the motor M is input. Further, the control circuit 1 outputs a control current I _S according to the drive voltage of the motor M to the bases of the transistors Tr2 and Tr3.

In the above structure, a part of the control signal I _S output from the control circuit 1 is input to the base of the transistor Tr2 and the rest is input to the base of the transistor Tr3. If the current amplification factor and base current of the transistor Tr2 are h _FE2 and I _b2 , and the current amplification factor and base current of the transistor Tr3 are h _FE3 and I _b3 , then h _{FE2
Currents of} I _b2 and h _FE3 · I _b3 flow. Transistor Tr
Since 2 and Tr3 are connected in parallel to the base of the transistor Tr1, the transistors Tr2 and Tr3 are
The sum of collector currents (h _FE2 · I _b2 + h _FE3 · I _b3 ) is
It becomes the base current I _{B1 of the} transistor Tr1. Therefore,
Assuming that the current amplification factor of the transistor Tr1 is h _FE1 , the output current I to the motor M is h _FE1 · I _B1 = h _FE1 · (h
_FE2 · I _b2 + h _FE3 · I _b3 ).

As described above, the base current I _B1 of the transistor Tr1 is supplied to the transistors Tr2 and Tr2.
Since it is shared by 3, the amplification degree of the output current I with respect to the control signal I _S can be increased, and the motor M can be reliably started even when the load is large. Further, the amplification factor of the output current I with respect to the control signal I _S is determined by the conventional transistor Tr2 and transistor Tr3.
Since it is smaller than the one with Darlington connected,
The stability of the rotation speed control of the motor M is not reduced.

FIG. 2 is a diagram showing the configuration of a second embodiment of the motor rotation speed control circuit according to the present invention. In addition, FIG.
It is a wave form diagram which shows the output current I in a 2nd Example. In the figure, instead of the transistor Tr3 of FIG. 1, a resistor R is connected in parallel to the transistor Tr2. In this embodiment, when the power switch SW is turned on, the resistance R
As a result, the base current I _R of the transistor Tr1 flows, and the current of h _FE1 · I _R is output to the motor M. However, the resistance R is set so that the output current h _FE1 · I _R becomes smaller than the current that can start the motor M, and even if the power switch SW is turned on, the control circuit 1 outputs the control signal I _{If S} is not output, the motor M will not start.

When the power switch SW is turned on and the control signal I _S is output from the control circuit 1, the transistor Tr
2 the collector current I _B2 of h _FE2 · I _S flows, and this current I
The sum of the current _B2 and the current I _R flowing through the resistor R becomes the base current I _{B1 of the} transistor Tr1. Therefore, the maximum value of the output current I increases as compared with the case where the resistor R is not connected in parallel with the transistor Tr2, because the resistor R partially shares the base current I _B1 . That is, as shown in FIG. 3, when the resistor R is not connected in parallel to the transistor Tr2, the maximum value of the output current I when the motor M is started is at the level (h _FE1 · h _FE2 · I _S ). However,
When the resistor R is connected in parallel with the transistor Tr2, the level becomes higher than the above level by h _FE1 · I _R (h _FE1 · (h _{F E2} · I _S + I _R )).

On the other hand, in controlling the rotation speed of the motor M after starting, the base current I _B2 shared by the transistor Tr2 is used.
Since the base current I _R shared by the resistor R is small in comparison with the above, the influence of the current I _{R on the} rotation speed control by the control signal I _S is small, and the stability of the rotation speed control is not deteriorated.

FIG. 4 is a diagram showing the configuration of a third embodiment of the motor rotation speed control circuit according to the present invention. In addition, FIG.
It is a wave form diagram which shows the output current I in a 3rd Example.

In FIG. 4, a capacitor C1 is provided instead of the resistor R of FIG. In this embodiment, when the power switch SW is turned on, a charging current I _C1 flows through the capacitor C1 and the base of the transistor Tr1 has a transistor Tr2 until charging of the capacitor C1 is completed.
Collector current I _B2 (= h _FE2 · I _S ) and the charging current I
The sum current of _C1 flows, and the base current I _B1 of the transistor Tr1 can be increased when the motor M is started. Therefore, the capacitance value of the capacitor C1 is appropriately set so that the maximum value of the output current I at the time of starting the motor (point A in FIG. 5) exceeds the maximum current required for starting the motor M (point B in FIG. 5). By setting, the motor M can be surely started.

On the other hand, after the charging of the capacitor C1 is completed, the collector current I _B2 (= h _FE2 · I _S ) of the transistor Tr2
Since the output current I is controlled only by itself, the rotation speed control of the motor M can be performed as in the conventional example shown in FIG. 11, and the stability of the rotation speed control is not deteriorated. In particular, even when the motor M is locked, the output current I is suppressed and does not become abnormally high.

FIG. 6 is a diagram showing the configuration of a fourth embodiment of the motor rotation speed control circuit according to the present invention. In the figure, a capacitor C2 is connected between the emitter of the transistor Tr1 and the base of the transistor Tr2 except for the capacitor C1 of FIG. 4, and the same effect as the third embodiment can be obtained.

In the fourth embodiment, when the power switch SW is turned on, the charging current I _{C2 of the} capacitor C2 flows to the base of the transistor Tr2, and when the motor M is started, the base current of the transistor Tr2 is the charging current I _C2.
And the control current I _S from the control circuit 1 is the sum of the currents. Therefore, at the time of starting the motor M, the transistor Tr
As the base I _{B1 of} 1 increases by _FE2 · I _C2, the output current I also increases by h _FE1 · h _{FE 2} · I _C2 .

In this embodiment, since the charging current I _C2 of the capacitor C2 flows through the base of the transistor Tr2 and can be made smaller than the charging current I _C1 of the capacitor C1 in the third embodiment, the capacity of the capacitor C2 is reduced. Can be smaller than the capacity.

FIG. 7 is a diagram showing the configuration of a fifth embodiment of the motor rotation speed control circuit according to the present invention. In addition, FIG.
It is a wave form diagram which shows the output current I in a 5th Example.

In FIG. 7, a switching transistor Tr4 is connected in series between the resistor R of FIG. 2 and the negative electrode of the power source E, and a timer 2 for controlling the driving of the transistor Tr4 is provided. The output terminal P of the timer 2 is connected to the base of the transistor Tr4, and the transistor Tr4 is on / off controlled by a control signal from the timer 2.

The timer 2 outputs the output terminal P when the power switch SW is turned on and the drive voltage is supplied from the power source E.
Outputs a high-level control signal from the transistor Tr
4 is turned on and the preset time T1
Start timing. Then, when the time measurement of the time T1 ends, a low-level control signal is output from the output terminal P to turn off the transistor Tr4. That is, the timer 2 increases the base current I _B1 of the transistor Tr1 by the amount of the current I _R flowing through the resistor R for the time T1 after the power switch is turned on.

Therefore, as shown in FIG. 8, the maximum current of the output current I at the time of start-up increases by the amount of the current I _R flowing through the resistance of the base current I _B1 , and accordingly increases by h _FE1 · I _R. However, similar to the fourth and fifth embodiments, the starting current required to start the motor M can be supplied sufficiently.

FIG. 9 is a diagram showing the configuration of a sixth embodiment of the motor rotation speed control circuit according to the present invention. In addition, FIG.
FIG. 6 is a timing chart showing the control of the output current I in the sixth embodiment, (a) is the output current, (b) is the motor drive voltage, and (c) is the timer output.

In FIG. 10, a voltage detection circuit 3 for detecting the drive voltage of the motor M is added in FIG. 7, and the operation of the timer 2 is controlled by the voltage detection circuit 3.

In the above fifth embodiment, the power switch SW
Since the base current I _B1 of the transistor Tr1 is increased until T1 elapses for a predetermined period after turning on,
As shown in FIG. 8, even when the motor M is started at the point C within the time T1, the output outflow I becomes larger than the current required to drive the motor M (the dotted line portion in FIG. 5), and from the point C The rotational speed of the motor M may become unnecessarily high until T1 elapses. In the present embodiment, the control for increasing the base current I _B1 of the transistor Tr1 is stopped at the timing when the motor M is completely started to prevent the rotation speed of the motor M from becoming higher than necessary. .

When the drive voltage of the motor M exceeds the threshold voltage V _{TH at} which the motor M is activated, the voltage detection circuit 3 outputs a control start signal to the timer 2 and forcibly ends the timer 2 timing operation. Then, the transistor Tr4 is turned off. That is, as shown in FIG. 10, when the power switch SW is turned on, the timer 2 outputs a high-level control signal from the output terminal P to turn on the transistor Tr4, and at the same time for a preset time T1. Start counting. Then, when the driving voltage V of the motor M rises to the threshold voltage V _TH while the timer 2 is measuring the time T1, a control stop signal is input from the voltage detection circuit 3 to the timer 2 and the timer 2 measures the time. After the forced termination, a low level control signal is output from the output terminal P to turn off the transistor Tr4.

In the above embodiment, the transistor Tr
1 is composed of a pnp type transistor, and a transistor Tr
Although 2 and Tr3 are configured by npn type transistors, the transistors Tr2 and Tr3 may be configured by pnp type transistors and the transistor Tr1 may be configured by npn type transistors.

[0041]

As described above, according to the present invention,
Connect a current control transistor in series between the power supply and the motor,
In a motor rotation speed control circuit for controlling an output current to the motor by controlling a base current of the current control transistor, controlling driving of the current control transistor between a base of the current control transistor and a negative electrode of the power supply. Since each drive control transistor is connected in parallel and the collector currents of both drive control transistors share the base current of the current control transistor, the range of output current to the motor with respect to the control current output from the control circuit Is increased and the motor can be reliably started even when the load is large.

Further, since the range of the output current with respect to the control current is smaller than that of the conventional two drive control transistors connected in Darlington, the rotation speed control of the motor after starting can be stably performed. .

Further, since the drive control transistor and the resistor are connected in parallel between the base of the current control transistor and the negative electrode of the power supply, the base current of the current control transistor is increased by the amount of current flowing through the resistor. The same effect as above can be obtained.

Further, in a motor speed control circuit in which a current control transistor is connected in series between the power supply and the motor and the output current to the motor is controlled by controlling the base current of the current control transistor, A capacitor is connected between the positive electrode and the base of the current control transistor, and the base current of the current control transistor is increased by the charging current of the capacitor while the capacitor is being charged. The output current to the motor becomes large only when the motor is running, and the motor can be reliably started. Further, after the motor is started, the rotation speed of the motor is controlled according to the load, so that the output current to the motor does not become abnormally high even when the motor is locked.

The control circuit has a timer,
Since the base current of the current control transistor is increased to a preset current value for a predetermined time after startup, the same effect as above can be obtained.

The control circuit has a detection circuit for detecting that the drive voltage of the motor exceeds a preset starting voltage, and the base current of the current control transistor is responsive to the detection of the detection circuit. Since the increase control of the motor is canceled, the output current to the motor increases only when a large current is required at the time of starting the motor, and the motor is reliably started, while the output current after starting depends on the load. It is limited to the current value, and the rotation speed does not become abnormally high.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a motor rotation speed control circuit according to the present invention.

FIG. 2 is a diagram showing a configuration of a second embodiment of a motor rotation speed control circuit according to the present invention.

FIG. 3 is a waveform diagram showing an output current in the second embodiment.

FIG. 4 is a diagram showing a configuration of a third embodiment of a motor rotation speed control circuit according to the present invention.

FIG. 5 is a waveform diagram showing an output current in the third embodiment.

FIG. 6 is a diagram showing the configuration of a fourth embodiment of the motor rotation speed control circuit according to the present invention.

FIG. 7 is a diagram showing the configuration of a fifth embodiment of the motor rotation speed control circuit according to the present invention.

FIG. 8 is a waveform diagram showing an output current in the fifth embodiment.

FIG. 9 is a diagram showing a configuration of a sixth embodiment of the motor rotation speed control circuit according to the present invention.

FIG. 10 is a timing chart showing the control of the output current in the sixth embodiment, where (a) is the output current, (b) is the motor drive voltage, and (c) is the timer output.

FIG. 11 is a diagram showing a circuit for controlling the rotation speed of a conventional DC motor.

FIG. 12 is a diagram showing a starting characteristic of a DC motor.

FIG. 13 is a diagram showing another circuit configuration of a conventional DC motor.

[Explanation of symbols]

 1 Control Circuit 2 Timer 3 Voltage Detection Circuit C1, C2 Capacitor E Power Supply R Resistance SW Power Supply Switch Tr1 to Tr4 Transistor

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[Procedure amendment]

[Submission date] December 7, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 4

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0005

[Correction method] Change

[Correction content]

By the way, the DC motor is generally shown in FIG.
The starting current is as shown in (1), and the current required at the time of starting is several times larger than the load current during rotation.
For this reason, when the power switch SW is turned on, the control circuit 1 causes the motor M to output a starting current that is several times the load current, and starts the motor M. After the start, the output current I becomes the load current. Limit the number of rotations of the motor M to a required value.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

The invention according to claim 4 comprises a current control transistor connected in series between the power supply and the motor, and a control circuit for controlling the base current of the current control transistor according to the drive voltage of the motor. the motor speed control circuit, the control circuit includes a timer, electrostatic
The base current of the current control transistor is increased to a preset current value for a predetermined time after the power switch is turned on .

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

A rotation speed control circuit for the DC motor according to claim 1.
According to the path , a part of the control current output from the control circuit is input to the base of one drive control transistor, and the rest is input to the base of the other drive control transistor.
Collector currents corresponding to the input base currents flow through the collectors of the double-acting control transistors, and the sum of these collector currents flows through the bases of the current control transistors. Then, a current obtained by amplifying this base current by the current amplification factor of the current control transistor is output to the motor. Since the base current of the current control transistor is shared by the collector currents of the two drive control transistors, the control range of the output current from the current control transistor with respect to the control signal of the control circuit becomes large.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

The rotation speed control circuit of the DC motor according to claim 2
According to the path , the base current of the current control transistor is the sum of the current flowing through the resistor and the collector current of the drive control transistor. As the base current of the current control transistor increases by the amount of current flowing through the resistor, the output current from the current control transistor increases and the control range of the output current for the control signal of the control circuit increases.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

The rotation speed control circuit of the DC motor according to claim 3
According to the road, when the power switch is turned on, a charging current flows into the capacitor, until the charging of the capacitor is completed, the control current for controlling the current control transistor (base current), only the charging current component Increase. The charging current may be supplied directly to the base of the current control transistor, and a drive control transistor is provided between the base of the current control transistor and the negative electrode of the power source to control the drive of the current control transistor. You may make it flow to the base of. As a result, when the motor is started, the control range of the output current with respect to the control current becomes large.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

The rotation speed control circuit of the DC motor according to claim 4
According to the path , when the power switch is turned on, the control circuit increases the base current of the current control transistor to a preset large current value and starts counting a predetermined time. Then, after a lapse of a predetermined time, the base current of the current control transistor is controlled to a value according to the drive voltage of the motor. As a result, the output current of the current control transistor increases for a certain period of time when the motor is started, and the motor is reliably started.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

The rotation speed control circuit of the DC motor according to claim 5
According to the path , when the power switch is turned on, the control circuit increases the base current of the current control transistor to a preset current value and starts counting for a predetermined time. If the drive voltage of the motor rises above a preset starting voltage before the elapse of a predetermined time, the base current of the current control transistor is controlled to a value according to the drive voltage of the motor. As a result, when the motor is started, the output current of the current control transistor increases and the motor is started reliably, and after the motor is started, the output current is limited to an appropriate output current according to the load.

Claims (5)

[Claims] 1. A motor rotation speed control circuit in which a current control transistor is connected in series between a power supply and a motor, and the output current to the motor is controlled by controlling the base current of the current control transistor. Of two drive control transistors connected in parallel between the base of the power source and the negative electrode of the power source and controlling the drive of the current control transistor, and the two drive control transistors according to the drive voltage of the motor.
And a control circuit for controlling the base current of each drive control transistor. 2. A current control transistor that is connected in series between a power supply and a motor and controls an output current to the motor, and is provided between a base of the current control transistor and a negative electrode of the power supply. In a motor rotation speed control circuit including a drive control transistor that controls drive and a control circuit that controls a base current of the drive control transistor according to a drive voltage of the motor, a resistor is connected in parallel to the drive control transistor. A motor rotation speed control circuit characterized in that. 3. A positive pole of the power source in a motor rotation speed control circuit in which a current control transistor is connected in series between the power source and the motor, and the base current of the current control transistor is controlled to control the output current to the motor. And a capacitor connected between the base of the current control transistor and the base of the current control transistor. 4. A motor rotation speed control circuit comprising a current control transistor connected in series between a power supply and a motor, and a control circuit for controlling a base current of the current control transistor according to a drive voltage of the motor, The control circuit includes a timer, and increases the base current of the current control transistor to a preset current value for a predetermined time after starting, the motor rotation speed control circuit. 5. The control circuit includes a detection circuit for detecting that the drive voltage of the motor exceeds a preset starting voltage, and the base of the current control transistor is responsive to the detection of the detection circuit. The motor rotation speed control circuit according to claim 4, wherein the increase control of the current is canceled.