JPH06217574A - Controller for dc motor - Google Patents

Abstract

PURPOSE:To make a brake to be surely actuated when the first switching element of a driving electric circuit is turned off by providing a by-pass circuit composed of a third switching element and diode in a controller provided with a second switching element which is controlled by an electronic governor circuit. CONSTITUTION:When a motor driving signal DRV is turned off, a motor driving circuit 10 outputs a stop signal STR and, after a time lag, outputs a braking signal BRK. Therefore, a first switching element Tr1 is turned off and a DC motor 1 continues rotation by inertia. Then a third switching element Tr3 is turned on and short-circuits the motor 1 through electric circuits 3 and 4 in cooperation with a diode 30. As a result, a brake is actuated. While the control signal CNT of an electronic governor circuit 20E is repeatedly set at an L and H levels and a second switching element Tr2 repeats turning off and turning on, the brake is surely actuated due to the parallel connection of the diode 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control device for a DC motor having a braking function.

[0002]

2. Description of the Related Art For example, a DC motor used as a rotational power source for feeding a print head or a sheet of a printer is driven and controlled at a constant rotational speed. The drive control device employed in such a case includes a motor drive circuit (10) and
It is generally composed of the centrifugal force detection governor 20M shown in FIG. 6 or the electronic governor circuit 20E shown in FIG.

In FIG. 4, a motor drive circuit 10 receives a motor drive signal DRV as an input, outputs a start signal STR (L level), turns on a first switching element Tr1 connected to a motor drive circuit 2, and turns on a DC motor. 1 is rotationally driven. Then, the centrifugal force detection governor 20M controls the rotation speed of the DC motor 1 to be constant. Vm is
It is a motor drive power supply.

On the other hand, the electronic governor circuit 20E shown in FIG.
Is the input of the rotation speed (pulse signal) SPD of the DC motor 1 detected by the speed detector 5 and the set speed signal,
A second switching element (not shown) connected to the motor drive circuit 2 is ON-OFF controlled to control the DC motor 1 to be equal to the set speed. Motor drive circuit 1
0 is the same as in the case of FIG.

By the way, for example, when it is applied to the above printer, it is necessary to shorten the start / stop time of the DC motor 1, especially the stop time, in order to increase the printing speed. Thus, when the centrifugal force detection governor 20M is adopted, as shown in FIG. 4, the electric line 3 connecting the first switching element Tr1 of the motor drive electric line 2 and the DC motor 1 to the ground.
A third switching element Tr3 that forms a brake circuit in the
Is connected to turn off the first switching element Tr1 and then turn on the third switching element Tr3 by the brake signal BRK to apply the brake.

That is, when the motor drive signal DRV is cut off (L level) at time t2 shown in FIG. 5, the motor drive circuit 10 outputs a stop signal (STR) (H level) to turn on the first switching element Tr1. The power is turned off and the motor drive power supply Vm is turned off. Therefore, the DC motor 1 rotates by inertia. Then, after the lapse of the time lag Δ2, the brake signal BRK is output (H level), the third switching element Tr3 is turned on, and the brake is applied. When the motor drive signal DRV is output (H level) at time t1, first, the brake signal BRK is cut off (L
Level), and after the time lag Δ1 has elapsed, the start signal STR
Is output (L level).

[0007]

However, when the electronic governor circuit 20E shown in FIG. 6 is adopted, even if the same brake circuit (10, Tr3) as in FIG. 4 is provided as shown by the chain double-dashed line. However, due to the characteristics of the electronic governor circuit 20E, a reliable brake cannot be applied. This is because the second switching element repeats ON-OFF. Therefore, it is necessary to provide a special and complicated brake circuit or brake device.

An object of the present invention is to provide a drive control device for a direct-current motor, which has a simple structure and can apply a reliable brake, and which is low in cost.

[0009]

A drive control device for a DC motor according to the present invention includes a motor drive circuit for turning on / off a first switching element connected to a motor drive circuit to stop driving the DC motor, and a motor. A drive control device for a DC motor, comprising: an electronic governor circuit for controlling ON / OFF of a second switching element connected to a drive circuit to make an actual rotation speed of the DC motor equal to a set rotation speed, The first of the motor drive circuit
A third switching element connected to one of an electric path connecting the switching element and the DC motor to the ground and a bypass electric path of the second switching element, and a diode connected to the other are provided, and 1
A brake signal generating circuit for generating a brake signal for turning on the third switching element after the switching element is turned off is provided.

[0010]

In the present invention having the above structure, when the first switching element is turned off, a brake signal is generated and output from the brake signal generating circuit to turn on the third switching element. Therefore, the electric path connecting the first switching element of the motor drive electric path and the DC motor to the ground is closed by, for example, the third switching element, and the bypass electric path of the second switching element is closed by the diode. Therefore, the second switching element in the electronic governor circuit is turned on.
The DC motor can be reliably braked even if it is repeatedly turned OFF.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the drive control circuit of the present DC motor has a basic structure including a motor drive circuit 10 and an electronic governor circuit 20E as in the conventional example (FIG. 6), and further includes a third switching element Tr3 and a diode 30. Even if the second switching element Tr2 in the electronic governor circuit 20E is repeatedly turned on and off when the first switching element Tr1 is turned off, the brake signal generating circuit (10) and the brake signal generation circuit (10) are provided. It is formed so that the brake can be applied.

The same parts as those of the conventional example (FIGS. 6 and 4) are designated by the same reference numerals, and the description thereof will be simplified or omitted.

In FIG. 1, the electronic governor circuit 20E
Is an F / V converter 21 for converting an actual rotational speed signal (pulse signal) SPD from the speed detector 5 connected to the DC motor 1 into a detected speed voltage signal E, the detected speed voltage signal E and a set speed signal. Vref. It is formed by a comparator 22 which receives and outputs as input and generates and outputs a control signal CNT, and a second switching element Tr2 which is turned on by the output (H level) of the comparator 22.

The F / V converter 21 receives the actual rotation speed signal (pulse signal) E as shown in FIGS.
When the frequency of becomes short, the detection speed voltage signal E is increased,
It is designed to be lowered as it becomes longer. In addition, the comparator 22 receives the inverted detection speed voltage signal E
And non-inverted input set speed signal (reference voltage signal) Vr
ef. And E> Vref. In the case of L level, E <Vref. In the case of
Is output. Therefore, the second switching element Tr2 connected to the motor drive circuit 2 (2B) is turned on and off.
The DC motor 1 can be controlled to have a constant speed. Set speed signal Vref. Is generated by the Zener diode ZD forming the reference voltage signal generating circuit.

Here, the motor drive circuit 2 (2A)
The third switching element Tr is provided in the electric path 3 connecting the first switching element Tr1 and the DC motor 1 to the ground.
3 is connected, and the diode 30 is connected to the bypass circuit 4 of the second switching element Tr2. Third
It can also be implemented by connecting the switching element Tr3 to the bypass circuit 4 and the diode 30 to the circuit 3.

Further, the motor drive circuit 10 is formed so as to output the start signal STR with the motor drive signal DRV as an input, as well as the brake signal BRK, as in the case of the conventional example. That is, the motor drive circuit (10) also forms a brake signal generation circuit. The output timings of the start signal STR and the brake signal BRK are shown in FIGS.
Shown in.

That is, when the motor drive signal DRV is input (H level) at time t1 in FIG. 2, the brake signal BRK is cut off (L level) and the start signal STR is output (L level) after the lapse of the time lag Δ1. To do. on the other hand,
At time t2 in FIG. 3, the motor drive signal DRV is OFF.
When (L level), the stop signal STR is output (H level) and after the time lag Δ2 has elapsed, the brake signal B
RK is output (H level).

In the embodiment having such a configuration, time t1 in FIG.
When the motor drive signal DRV is input (H level) at, the brake signal generation circuit (10) causes the brake signal B
RK is turned off (L level) to release the brake, and the motor drive circuit 10 starts the start signal S after the time lag Δ1 has elapsed.
Output TR (L level). Therefore, the third of FIG.
Since the switching element Tr3 is OFF and the first switching element Tr1 and the second switching element Tr2 are ON, the DC motor 1 starts to rotate by the motor drive power source Vm. The output voltage (detected speed voltage signal) SPD from the speed detector 5 during acceleration of the DC motor 1 and F
The waveforms of the output signal E from the / V converter 21 and the output signal (control signal) CNT from the comparator 22 are
This is as shown in FIG. The relationship between the actual speed (E) of the DC motor 1 and the set speed (Vref.) Is E> Vr.
ef. And the control signal CNT becomes L level, and E <Vre
f. Becomes H level. By repeating this, the second switching element Tr2 is ON-OFF controlled and the DC motor 1 is controlled at a constant speed.

Next, at time t2 in FIG. 3, the motor drive signal D
When the RV is OFF (L level), the motor drive circuit 1
0 outputs the stop signal STR (H level), and the brake signal generation circuit (10) outputs the brake signal BRK (H level) after the lapse of the time lag Δ2. Therefore, the first switching element Tr1 is turned off and the DC motor 1
Continues to rotate due to inertia. On the other hand, the third switching element T
Since r3 is turned on, in cooperation with the diode 30, the DC motor 1 is shot through the electric paths 3 and 4, whereby the brake is applied.

At this time, since the control signal CNT repeats L level and H level, the second switching element Tr2 becomes OF.
Although F-ON is repeated, the diode 30 is connected in parallel with the second switching element Tr2, so that the brake can be reliably applied.

According to this embodiment, however, the third switching element Tr3 is connected to the electric path 3 connecting the first switching element Tr1 of the motor drive electric path 2 (2A) and the DC motor 1 to the ground. A brake signal generation circuit (10) is provided which connects the diode 30 to the bypass circuit 4 of the second switching element Tr2 and turns on the third switching element Tr3 after the first switching element Tr1 is turned off. In terms of characteristics, that is, since the brake can be continuously applied even when the second switching element Tr2 is in the OFF state, reliable braking can be applied, and the structure is simple and the cost is low.

Further, the brake signal generating circuit (10) is
The motor drive circuit 10 is also used as the motor drive circuit 10, and the start signal STR and the brake signal BRK have time lags Δ1 and Δ2.
Since it is formed so as to output with, it is possible to smoothly start and stop.

[0023]

According to the present invention, the first motor drive circuit is provided.
A third switching element connected to either one of an electric path connecting the switching element and the DC motor to the ground and a bypass electric path of the second switching element, and a diode connected to the other, and first switching A brake signal generating circuit for generating a brake signal for turning on the third switching element after the element is turned off is provided, and the characteristic of the electric governor circuit, that is, the second
Since the brake can be continuously applied even when the switching element is in the OFF state, reliable braking can be applied, and the structure is simple and the cost is low.

[Brief description of drawings]

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

FIG. 2 is likewise a timing chart at the time of startup.

FIG. 3 is likewise a timing chart when stopped.

FIG. 4 is a circuit diagram for explaining a conventional example using a centrifugal force detection governor.

FIG. 5 is likewise a timing chart.

FIG. 6 is a circuit diagram for explaining a conventional example using an electronic governor circuit.

[Explanation of symbols]

 1 DC motor 2, 2A, 2B Motor drive circuit 3 Circuit 4 Bypass circuit 5 Speed detector 10 Motor drive circuit (brake signal generation circuit) 20E Electronic governor circuit 20M Centrifugal force detection governor 21 F / V converter 22 Comparator 30 Diode Tr1 Tr3 First to third switching elements

Claims (1)

[Claims] 1. A motor drive circuit for turning on and off a first switching element connected to a motor drive circuit to stop driving a DC motor, and an on-off control for a second switching element connected to the motor drive circuit. And a DC motor drive control device for controlling the actual rotation speed of the DC motor so as to equalize the actual rotation speed with the set rotation speed. A third switching element connected to either one of the electric path connecting the ground and the ground and the bypass electric path of the second switching element, and the diode connected to the other side, and the first switching element is OF
A drive control device for a DC motor, comprising a brake signal generating circuit for generating a brake signal for turning on the third switching element after being turned off.