JPH0343864B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speed control device for a servo motor. The present invention relates to a speed control device for controlling the speed of a servo motor.

Conventionally, a speed control device for a servo motor combines one control device with one servo motor to control its speed.

Therefore, when simultaneously controlling the speed of two or more servo motors separately, two or more control devices are required, and the number of parts of the device is large, resulting in a decrease in reliability. It has the drawbacks of being expensive, large, and expensive.

In addition, in controlling the rotation speed ratio of multiple motors to a constant value, each rotation speed detection signal is taken into each control section separately, and since there is no relationship between each control section, each rotation speed control configuration This has the disadvantage that the control must be made more precise than necessary, making the control complex and expensive.

In addition, Japanese Patent Application Laid-open No. 1973 entitled "Driving method of electric motor"
Publication No. 128215 discloses a technique in which one or more electric motors constitute one motor group, and the electric motors of the plurality of groups constituted in this way are simultaneously rotated at the same rotation speed. ,
This will be discussed later.

An object of the present invention is to control the speed of a plurality of servo motors when controlling the speed of a drum rotation drive motor and a light source drive motor in a copy machine, for example. The speed of the servo motor is controlled by one control unit, and the control unit can be shared, and the speed of two or more motors can be controlled simultaneously with a small number of parts. In order to keep the rotation speed ratio of each servo motor constant, the rotation speed detection signal of each servo motor is input into each control section separately, and unrelated individual rotation speed control configurations between each control section are unnecessary. To provide an inexpensive and highly reliable speed control device for a servo motor, which can eliminate the problem of complicated and expensive control that requires precision.

The object is to provide a servo motor, a two-phase encoder that is provided on the servo motor and has a mutual phase difference and that generates a frequency proportional to the number of rotations of the servo motor, and a two-phase encoder that generates a two-phase signal from the encoder. a rotational direction determining unit that determines the rotational direction of the servo motor based on advance/lag, a counter that measures a rotational speed detection signal obtained from the encoder for a predetermined period of time, and a motor rotational direction determination signal from the encoder and the rotational speed from the counter. A control section that outputs a new motor rotation direction signal and speed signal based on the detection signal and further an external command, and a drive section that drives the servo motor based on the motor rotation direction signal and speed signal from the control section. A speed control device for a servo motor, wherein the servo motor is composed of a plurality of servo motors, and the encoder, a motor rotation direction determining section,
The counter and motor drive section are configured by a plurality of encoders, a motor rotation direction determination section, a counter, and a motor drive section corresponding to the plurality of servo motors; servo motors, encoders,
It is composed of a servo motor rotation direction determination section, a counter, and one control section common to the motor drive section, and further, between the plurality of counters and one control section, there is a motor control section from each of the counters. one rotational speed detection signal switching section that switches the rotational speed detection signal in response to a switching signal from the control section and stores it in the control section, and the one control section and the plurality of motor drive sections and a command value switching section for selectively switching the control signal from the control section to one of the controlled servo motors; When controlling the speed of each servo motor by reading _{an output} proportional to motor V _F ′
(rotation speed proportional output), and if the above-mentioned V _F and V _F ′ are V _F = V _F ′, then the only servo motor
Compare V _F with the external speed command value, and if V _F = external speed command value, send it to the previous command value switching section as V _F = V _F ′ = external speed command value, and conversely, V If _F ≠ external speed command value, then V _F = external speed command value, that is, V _F = V _F ′ = external speed command value, and send it to the previous command value switching section, and on the other hand, V _F and V _F ′ is V _F ≠V _F ′, then V _F of the only servo motor is compared with the external speed command value, and if V _F = external speed command value, this V _F is further compared. As a standard, V _F = V _F ′, that is, V _F = V _F ′ = corrected to the external speed command value and sent to the previous command value switching section.On the contrary, if V _F ≠ external speed command value , this is also the only servo motor mentioned above.
Using V _F as a reference, V _F = external speed command value. Further, using this V _F as a reference, V _F = V _F ′, that is, V _F = V _F ′ = external speed command value, and then correct it to the previous command value switching section. Along with sending
When changing the rotation speed ratio between the only servo motor and other servo motors, input only the ratio of the other servo motors to the rotation speed of the only servo motor into the control unit, and change the rotation speed ratio between the only servo motor and the other servo motor. This is achieved by providing means for driving the motor and the other servo motor at a constant rotation speed ratio.

Next, an embodiment of the speed control device according to the present invention will be described based on FIGS. 1 and 2.
FIG. 1 is a block diagram showing the overall configuration, and FIG. 2 is a flowchart showing the operating system of the speed control device shown in FIG.

In FIG. 1, 1 is a control unit, 2 is a rotation command value switching unit, 3 and 3' are drive units, 4 and 4' are rotation direction determination units, and 5 and 5' are counters related to motor rotation speed detection means; 6 is a V _F /V _F ' switching unit related to the output switching device of the counter 5, M ₁ and M ₂ are servo motors, and E ₁ and E ₂ are encoders related to the rotation signal generating device.

In other words, an encoder E ₁ is attached to the motor M 1, which generates frequency signals φ _A1 and φ _B1 that have different phases and are proportional to the rotation speed of _the motor M ₁ , and an encoder E ₂ is attached to the motor M ₂ as well. and generates the same signals φ _A2 and φ _B2 . These signals φ _A1 , φ _B1 and φ _A2 , φ _B2 are determined by rotation direction determining sections 4' and 4, respectively, from the phase difference of the signals, and the rotation direction of the motor is inputted into the control section 1. Further, φ _A1 , φ _B1 and φ _A2 , φ _B2 are counted by counters 5', 5 for a time Ts specified by the control section 1, and the outputs V _F ', V _F are as follows.
The V _F /V _F ' switching unit 6 sequentially inputs the switching signal C ₂ from the control unit 1 into the control unit 1 .

The control unit 1 outputs an output signal for determining the rotation direction;
V _F /V _F ′, and the speed command value from outside the control system,
Depending on the normal rotation/reverse rotation signal, for example, in the case of normal rotation, both the rotation command A and signal are output, and in the case of reverse rotation, both the rotation command signal B is output. In this case, signals such as A and B are
In other words, in the case of forward rotation or reverse rotation, the energization time is controlled so that the motor rotation speed matches the speed command value by comparing V _F /V _F ' with the speed command value (PWM control, that is, pulse width control). ).

The command value switching unit 2 switches the speed command values to the drive circuit 3 of the motor M ₁ and the drive circuit 3' of the motor M ₂ in response to the switching signal C ₁ .

The drive units 3 and 3' receive a latch signal from the control unit 1.
It consists of a latch circuit that latches the speed command value using L ₁ and L ₂ , and a power amplification circuit that amplifies the signal enough to drive the motors M ₁ and M ₂ . In addition to the above-mentioned external command signal, the control unit 1 receives
Start, stop, motor M ₁ , M ₂ commands, N
₁ /N ₂ (speed ratio signal of motors M ₁ and M ₂ ), etc. are input from the outside.

The present invention has the above configuration, and according to the present invention, the following control is possible.

First, the rotation speeds of motor M ₁ and motor M ₂ can be controlled to be exactly the same by external input (N ₁ /N ₂ =1).

Second, the rotation speeds of motor M ₁ and motor M ₂ can be controlled at a certain ratio.

Thirdly, motor M ₁ and motor M ₂ can be controlled completely separately and at independent rotation speeds.

An example of controlling the rotation speed of motor M ₁ to be the same based on the rotation speed of motor M ₂ will be explained with reference to the control flowchart of FIG. 2. It goes without saying that the rotation speed of the motor _M1 may be used as a reference.

First, the control unit 1 selects the following from the counters 5 and 5'.
Read V _F /V _F ′, which is proportional to the motor rotation speed. Next, compare V _F and V _F ′, and if V _F = V _F ′, that is, when motors M ₂ and M ₁ rotate at the same time, V _F
is compared with the external speed command value. If V _F is not equal to the speed command value, a comparison is made to see if V _F is larger or smaller than the speed command value.

Therefore, in the case of V _F = V _F ′, calculation processing is performed for each of the cases where V _F is equal to the speed command value, when it is greater than the speed command value, and when it is smaller than the speed command value.
The speed command value to be given to the motor is calculated by (5), (3), and (4), and is output from A, B, or in Figure 1.

In this case, for example, calculation processing (3) is
Since V _F is large, that is, the rotational speed is high, it goes without saying that a speed command value that reduces the rotational speed is issued.

Similarly, when V _F ≠ V _F ′, the external speed command value and V _F are first compared, and when the external speed command value = V _F , the motor M ₂
The speed command value for motor M 1 is calculated first, and then the speed command value for motor M ₁ is calculated based on the magnitude of V _F and V _F ′. In this case, in calculation processes (6) and (7),
V _F ' is used as the value to be compared with the speed command value from outside the control system. The same applies when the command value≠V _F. In this way, V _F and V _F ' can be read into the control unit 1 at the same time and controlled to always have the same rotational speed.

Next, the external signals input to the control section 1 will be explained.

The start signal is a signal that starts the motor operation, the stop signal is a signal that stops the motor operation, the forward/reverse signal is a signal that causes the motor to rotate forward or reverse, and the speed command value is a signal that specifies the rotational speed of the motor.

Further, the M ₁ and M ₂ commands are signals for determining whether the four external signals are directed to motor M ₁ or motor M ₂ . N ₁ /N ₂ is motor M ₂
(or M ₁ ), the motor
This is a speed ratio signal that indicates the speed ratio of M ₁ (or M ₂ ).

The N ₁ /N ₂ signal in the previous example (motor M ₂
(based on the rotation speed), use as follows. That is, a constant rotation speed command is given to the motor _M2 , and the motor M2 is rotated at a constant rotation speed. Then, N ₁ /N
From the ₂ command, the rotation command of motor M ₁ is
Given as a ratio of _M2 .

In this case, the control unit 1 controls so that N ₁ /N ₂ becomes a constant ratio. For example, even if the standard N ₂ changes due to sudden changes in load, N ₁ and N
Changes to maintain the ₁ / _N2 ratio.

As described above, according to the embodiment specifically illustrating the present invention, the number of rotations of two or more servo motors can be controlled simultaneously using one control unit 1, so the circuit configuration is simplified. In addition to being cheaper,
Reliability can be improved.

In addition, by simultaneously storing rotation information V _F /V _F ', command values, etc. of multiple motors in the control unit 1, it is possible to control the rotation speed ratio to a constant value, as described in detail above. Its practical value is extremely great. For example, it becomes an optimal control device for a copy machine that can be reduced in size. For reducible copy machines, for example Motor M ₁
is used to drive the rotation of the drum, and Motor _M2 is used to drive the light source. Note that when the copy size is 1:1, the rotation speeds of motor M ₁ and motor M ₂ may be controlled to be the same. In such a case, if the rotational speed of the drum changes due to changes in the load, conventionally, the rotational speeds of the drum rotation drive motor and the light source drive motor are controlled separately to a constant value. Therefore, fluctuations in the rotation speed of one cannot be detected by the other control device. Therefore, in the past, in order to keep the rotation speed ratio of the plurality of servo motors constant as described above, it was necessary to control the rotation speed of each individual motor extremely precisely, which increased the number of parts in the control section. ,
This led to larger sizes, higher prices, and lower reliability.

On the other hand, in the present invention, the rotation speeds of a plurality of servo motors are controlled simultaneously by one control section, and the control section always captures the rotation speed of each motor. By comparing the motor rotation speed from moment to moment, it is possible to always control the rotation speed to a constant ratio. Therefore, the control precision of each rotation speed is not required so much, and with a simple configuration,
Accurate control is possible at low cost.

In addition, in the case of the previous example (based on the rotation speed of motor M ₂ ), if you want to change the rotation speed ratio of motor M ₁ to motor M ₂ in order to make a reduced copy, the rotation speed of motor M ₂ Since it is only necessary to input the ratio of the motor M ₁ to the number and there is no need to input the speed command value of the motor M ₁ again, the input device can also be simplified.

In addition, Japanese Patent Application Laid-open No. 1973 entitled "Driving method of electric motor"
Publication No. 128215 discloses a technique in which one or more electric motors constitute one motor group, and the electric motors of the plurality of groups constituted in this way are simultaneously rotated at the same rotation speed. ,
The technology disclosed in this publication relates to speed control of electric motors that have a very large inertial load that continues to rotate for several to tens of hours even after the power is turned off after acceleration, and is divided into the aforementioned multiple groups. This method connects each group to the power supply in a time-divided manner, and not only is the means for solving the problem completely different from the present invention, but it also uses the power on/off control described in the same publication. In the end,
It is impossible to control a fast rise time and reach a target speed quickly, such as with a servo motor with small inertia, such as in a copy machine.

The present invention is as described above, and the present invention is directed to controlling the speed of a plurality of servo motors, such as when controlling the speed of a drum rotation drive motor and a light source drive motor in a copy machine, for example. In doing so, the speeds of the plurality of servo motors are controlled by a single control section, the control section is shared, and the speeds of two or more motors are controlled simultaneously with a small number of parts. According to the present invention, like conventional devices of this type,
In order to keep the rotation speed ratio of multiple servo motors constant, the rotation speed detection signal of each servo motor is input into each control section separately, and an unrelated individual rotation speed control configuration is required between each control section. It is possible to provide an inexpensive and highly reliable servo motor speed control device that can eliminate problems that require higher precision, complicated control, and higher costs. The effects obtained are very large.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a block diagram showing the overall configuration of the speed control device according to the present invention, and FIG. 2 is a flowchart showing the operating system of the speed control device shown in FIG. be. DESCRIPTION OF SYMBOLS 1... Control part, 2... Command value switching part, 3, 3'... Drive part, 4, 4'... Rotation direction determination part, 5, 5'... Counter, V _F ... Output of counter 5, V _F '... Counter 5' output, 6...V _F /V _F ' switching section, M ₁ , M ₂
…Servo motor, E ₁ , E ₂ … Encoder.

Claims (1)

[Scope of Claims] 1. A servo motor, a two-phase encoder that is provided on the servo motor and that generates a frequency proportional to the number of rotations of the servo motor and that has a mutual phase difference, and A rotation direction determination unit that determines the rotation direction of the servo motor based on the advance or delay of the phase signal, a counter that measures the rotation speed detection signal obtained from the encoder for a predetermined period of time, and a motor rotation direction determination signal from the encoder and the counter. a control unit that outputs a new motor rotation direction signal and a speed signal based on the rotation speed detection signal and further an external command; and a drive that drives the servo motor based on the motor rotation direction signal and speed signal from the control unit. In the servo motor speed control device, the servo motor is configured by a plurality of servo motors, and the encoder, motor rotation direction determination section, counter, and motor drive section are also configured by the plurality of servo motors. The controller includes a plurality of encoders, a motor rotation direction determination section, a counter, and a motor drive section corresponding to the servo motors, and the control section includes a plurality of servo motors, encoders, and a servo motor rotation direction determination section. , counter, common to motor drive unit 1
The motor rotation speed detection signal from each of the counters is switched between the plurality of counters and the one control section by a switching signal from the control section. A rotation speed detection signal switching section is provided to capture and store the rotation speed detection signal in the control section, and a control signal from the control section is provided between the one control section and the plurality of motor drive sections. The control unit includes one command value switching unit that selectively switches the controlled servo motors, and the control unit reads an output proportional to the rotation speed of the controlled servo motors to control the speed of each servo motor. In this case, based on the output V _F proportional to the rotation speed of one servo motor,
Compare V _F of this only servo motor with V _F ′ (rotation speed proportional output) of other controlled servo motors, and if V _F and V _F ′ are V _F =V _F ′, Furthermore, the only servo motor
Compare V _F with the external speed command value, and if V _F = external speed command value, send it to the previous command value switching section as V _F = V _F ′ = external speed command value; If V _F ≠ external speed command value, then V _F = external speed command value, that is, V _F = V _F ′ = external speed command value, and send it to the previous command value switching section _. If _F ′ is V _F ≠V _F ′, also compare V _F of the only servo motor with the external speed command value, and if V _F = external speed command value, then this V _F is corrected to V _F = V _F ′, that is, V _F = V _F ′ = external speed command value, and sent to the previous command value switching section. Conversely, if V _F ≠ external speed command value, This is also the only servo motor mentioned above.
Using V _F as a reference, V _F = external speed command value. Further, using this V _F as a reference, V _F = V _F ′, that is, V _F = V _F ′ = external speed command value, and then correct it to the previous command value switching section. Along with sending
When changing the rotation speed ratio between the only servo motor and other servo motors, input only the ratio of the other servo motors to the rotation speed of the only servo motor into the control unit, and change the rotation speed ratio between the only servo motor and the other servo motor. 1. A servo motor speed control device comprising means for driving a servo motor and another servo motor at a constant rotation speed ratio.