JPH01268472A - motor control circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a motor control circuit, and more particularly to a motor control circuit that performs feedback control of the motor rotation speed by comparing a motor rotation detection signal with a reference frequency signal. .

[Prior art]

Conventionally, in this type of motor control circuit, there are two methods of obtaining a reference frequency signal by dividing a reference clock from an oscillation circuit including a crystal oscillator connected to the control circuit, and a method of obtaining a reference frequency signal from an external part of the motor control circuit, for example, a microcomputer. There is a method of obtaining a frequency signal [Problem to be solved by the invention] In the method of obtaining a reference frequency signal by dividing a reference clock, the motor can be controlled by a motor control circuit alone, but for example, a microcomputer Unification, that is, chronological linkage, with peripheral devices such as

On the other hand, in the method of applying a reference frequency signal from the outside, a common clock is used, so uniformity with peripheral devices can be maintained, but the motor cannot be controlled by the motor control circuit alone. Furthermore, if both methods are attempted to be achieved with a single IC, the number of IC pins will increase, which is not desirable for IC implementation.

Therefore, the main purpose of this invention is to
It is an object of the present invention to provide a motor control circuit in which a reference frequency signal can be generated internally or supplied externally.

[Means for Solving the Problems] The present invention provides a motor control circuit that controls the number of rotations of a motor by comparing a motor rotation detection signal with a reference frequency signal. When an oscillator is connected, the first path divides the clock from the oscillation circuit that includes the oscillator and outputs a reference frequency signal, and when a pulse signal is input to the input terminal, the pulse signal is directly referenced. a second path for outputting as a frequency signal;
an output terminal for outputting a reference frequency signal, and a first
The motor control circuit includes switching means for selectively connecting the output of the first path and the second path to the output terminal.

[Effect]

When the oscillator is connected to the input terminal, the output of the first path is connected to the output terminal by the switching means. Therefore, the clock from the oscillation circuit including the oscillator is frequency-divided in the first path, and the obtained reference frequency signal is output from the output terminal through the switching means.

On the other hand, when a pulse signal is input to the input terminal, the output of the second path is connected to the output terminal by the switching means. Therefore, in this case, the pulse signal is directly output from the output terminal as the reference frequency signal through the switching means.

〔Effect of the invention〕

According to this invention, a reference frequency signal can be obtained by connecting an oscillator to the input terminal, or a pulse signal input to the input terminal can be used as it is as the reference frequency signal. Therefore, depending on the application, the motor can be controlled by the motor control circuit alone, or the motor control circuit can be controlled by a microcomputer, for example, and the motor cannot be controlled without maintaining chronological consistency with other circuits. can also be controlled.

In other words, when controlling the motor with the motor control circuit alone, it is sufficient to connect an oscillator to the input terminal, and when controlling the motor while maintaining connection with peripheral circuits, it is necessary to input pulse signals output from, for example, a microcomputer. Just give it to the terminal.

In this way, even when inputting a reference frequency signal from the outside, it is only necessary to apply the reference frequency signal to the input terminal to which the oscillator can also be connected.
Therefore, it is advantageous for IC implementation.

The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

〔Example〕

FIG. 1 is a block diagram showing one embodiment of the present invention.

The motor control circuit 10 includes a drive circuit 12, and the rotation speed of the motor 14 is controlled by the drive circuit 12.

The rotation speed of the motor 14 is detected by a magnetic sensor 16 made of, for example, a Hall IC.

The output of the magnetic sensor 16, ie, a signal indicating the rotation speed of the motor 14, is input to the signal processing circuit 18.

The signal processing circuit 18 amplifies the manually input signal and performs waveform shaping, and then outputs it to the comparison circuit 20 as a rotation detection signal. The comparison circuit 20 also receives a reference frequency signal.

A crystal oscillator 24 or a pulse signal source 26 such as a microcomputer can be connected to the input terminal 22 of the motor control circuit 10 via a switch 23. By switching the switch 23,
A crystal oscillator 24 can be connected to the input terminal 22, or a pulse signal from a pulse signal source 26 can be applied.

When controlling the motor 14 by the motor control circuit 10 alone, a crystal oscillator 24 is connected to the input terminal 22. on the other hand,
When this motor control circuit 10 is controlled by, for example, a microcomputer (not shown), a pulse signal is output from a pulse signal source 26 such as a microcomputer.

The reference frequency generation/supply circuit 28 becomes an oscillation circuit and a frequency dividing circuit when the crystal oscillator 24 is connected to the input terminal 22, and outputs an oscillation signal with a frequency determined according to the crystal oscillator 24 to the frequency dividing input terminal 28b. The frequency is divided according to the frequency division ratio data applied to. Note that a frequency division command is input to the switching terminal 28a, and a reference frequency signal is output to the output terminal of the reference frequency generation/supply circuit 28.

On the other hand, when the input terminal 22 is supplied with a pulse signal from the pulse signal source 26, that is, a reference frequency signal,
Since there is no need to perform frequency division, a low level is applied to the switching terminal 28a, and the frequency division function is stopped. therefore,
At this time, the pulse signal from the pulse signal source 26 is directly output from the reference frequency generation/supply circuit as a reference frequency signal.

The comparison circuit 20 compares the rotation detection signal given from the signal processing circuit 18 and the reference frequency signal given from the reference frequency generation/supply circuit 38, and calculates the rotation detection signal according to the deviation between the rotation detection signal and the reference frequency signal. Then, for example, a voltage signal having a magnitude corresponding to the deviation is output to the drive circuit 12. The drive circuit 12 controls the motor 14 to rotate at a constant rotation speed by increasing or decreasing the rotation speed according to the voltage signal.

Figures 2 and 3 show the reference frequency generation/
2 is a circuit diagram showing a specific embodiment of the supply circuit, FIG. 2 shows a case where a crystal oscillator 24 is connected to the input terminal 22, and FIG. 3 shows a case where a pulse signal (external pulse signal source) is connected to the input terminal 22. ) from 26 is given.

Input terminal 22 is connected to a series connection point of two resistors 34a and 34b on the negative (-) side of differential amplifier 34. Two resistors 34c are also connected to the positive terminal of the differential amplifier 34.
and 34d are connected in series. The other ends of the resistors 34b and 34d are commonly connected and connected to the output terminal of the differential amplifier 34. In this way, the input terminal 22
An oscillation circuit is constructed by connecting the crystal oscillator 24 to the input terminal 22 by connecting the differential amplifier 34 to the connection point between the negative (-) side resistors 34a and 34b of the four resistors 34a to 34d. Ru.

Furthermore, when the pulse signal source 26 is connected, it operates as an amplifier circuit.

The output from the differential amplifier 34 is a bipolar output type buffer 3.
6, a programmable frequency divider 40 and a comparator 4
given to 2. The programmable frequency divider 40 is a high-speed type, and divides the clock (for example, about 1 to 12 MHz) from the oscillation circuit including the crystal oscillator 24 according to frequency division ratio data output from a microcomputer or the like. and outputs it to one input terminal of the switching circuit 44. Comparator 42 can only operate in a frequency range from direct current to alternating current of about 300 kHz. Therefore, even if a clock is given from the oscillation circuit including the crystal oscillator 24, the frequency of the clock will be 1 to 12 MHz as described above.
z and high frequency, comparator 42 does not respond to that clock. That is, the comparator 42 passes only a relatively low frequency pulse signal (reference frequency signal). The output of the comparator 42 is applied to the other input terminal of the switching circuit 44.

The switching circuit 44 outputs the output of the programmable frequency divider 40 or the output of the comparator 42 as a reference frequency signal depending on the switching signal, that is, the high level or low level of the switching terminal 28a. Therefore, when the crystal oscillator 24 is connected to the input terminal 22 as shown in FIG. It is output from the switching circuit 44 as a reference frequency signal.

Further, as shown in FIG. 3, when a pulse signal source 26 is connected instead of the crystal oscillator 24, the input terminal 22 is connected to the output of the transistor 46. A pulse signal from the pulse signal source 26 is applied to the input or base of this transistor 48 via a resistor. In this way, the pulse signal from the pulse signal source 26 is applied to the input terminal 22. By connecting a transistor circuit as shown in FIG. This allows low-frequency pulse signals to be input.

The pulse signal from the pulse signal source 26 has a frequency of 3
Since it is a low frequency of 00kHz or less, it is within the response range of the comparator 42. Therefore, when a pulse signal is given from the pulse signal source 26, the pulse signal is outputted from the comparator 42 to the switching circuit 44. Ru. When the pulse signal source 26 is connected to the input terminal 22,
Since the switching signal is, for example, at a low level, the output of the comparator 42 is directly output from the switching circuit 44 as a reference frequency signal.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. Figures 2 and 3 are block diagrams showing the main parts of the embodiment shown in Figure 1. Figure 2 shows the case where a crystal oscillator is connected, and Figure 3 shows the case where a pulse signal source is connected. shows. In the figure, 14 is a motor, 22 is an input terminal, 24 is a crystal oscillator, 26 is a pulse signal source, 28 is a reference frequency generation/supply circuit, 34 is a differential amplifier, 34a to 34b are resistors, and 40 is a programmable frequency divider. 42 is a comparator, and 44 is a switching circuit. Patent applicant: Sanyo Electric Co., Ltd. (and 1 other person) Agent: Patent attorney Yama 1) Gijinzo 1 Figure 21. ? 1 447-

Claims (1)

[Claims] 1. In a motor control circuit that controls the number of rotations of a motor by comparing a motor rotation detection signal with a reference frequency signal, an input terminal, when an oscillator is connected to the input terminal. a first path for dividing a clock from an oscillation circuit including the oscillator and outputting the reference frequency signal;
a second path for directly outputting the pulse signal as the reference frequency signal when a pulse signal is input to the input terminal, an output terminal for outputting the reference frequency signal, the first path, and the first path; A motor control circuit comprising switching means for selectively connecting outputs of two paths to the output terminal. 2. An input circuit is connected to the input terminal, and the input circuit includes a differential amplifier, two resistors connected in series between one input and output of the differential amplifier, and the other resistor of the differential amplifier. 2. The motor control circuit according to claim 1, further comprising two resistors connected in series between an input and an output, and wherein the input terminal is connected to a connection point between the two resistors. 3. The motor control circuit according to claim 1 or 2, wherein the second path includes a circuit that passes only low frequency signals. 4. The motor control circuit according to any one of claims 1 to 3, wherein the first path includes a programmable frequency divider for dividing the frequency of the clock.