JP2001157480A - Brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a brushless motor 1a on/off controlled in response to the rotation/stop of a rotor 6 to supply a power to a rotation detecting means 7 for detecting the rotating position of the rotor 6 without increasing the number of wirings to the motor. SOLUTION: A communication managing means 4a for turning on, off the supply of a power to the rotation detecting means 7 in response to the change of the period, the duty ratio or the amplitude of a clock signal 19 as the reference of controlling the rotational speed of the rotor 6 by externally inputting is provided in the brushless motor 1a. This can remarkably conduct a power conservation in an equipment complicately repeating the rotation/the stop of the rotor 6 and having a large ratio of the stopping state such as in a floppy disk driver or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor provided with a driving circuit, and more particularly to a power-saving brushless motor which performs control so as to reduce power consumption during standby when the motor is not rotating.

[0002]

2. Description of the Related Art A conventional brushless motor (20) will be described with reference to FIG. FIG. 5A is a configuration diagram of a brushless motor (20) according to the related art, and FIG. 5B is a table for describing setting of a rotation speed in the brushless motor (20) according to the related art.

A brushless motor (20) according to the prior art shown in FIG. 5 (A) has a rotor (6) having a magnet (2) for magnetizing a multipole in a circumferential direction to generate a field magnetic field.
And a stator having a polyphase drive coil (3) opposed to the magnet (2) and linked to the field magnetic field, and a field magnetic field generated by the magnet (2) using the Hall element (15). Rotation detecting means (7) for detecting the rotational position of the rotor (6) and applying a driving current to the driving coil (3) in accordance with the detection output of the rotation detecting means (7) to generate a rotating magnetic field. And a driving circuit (8) for generating a rotating force by an interaction between a field magnetic field of the magnet (2) and a rotating magnetic field of the driving coil (3) to rotate the rotor (6). ing.

Further, the brushless motor (20) has a frequency generator magnet (not shown) which is magnetized in multiple directions in the circumferential direction on the outer periphery of the rotor (6), and faces the frequency generator magnet. A frequency generator coil (16) provided on the stator, and a motor speed detection circuit (9) connected to the frequency generator coil (16).

[0005] When the rotor (6) rotates, a signal having a frequency corresponding to the number of rotations is transmitted to the frequency generator coil (1).
6), the motor speed detection circuit (9) detects the rotation speed of the rotor (6) from the induced signal.

[0006] The brushless motor (20) includes a frequency dividing circuit (21) and a control circuit (14). These functions will be described later.

FIG. 5B is a table for explaining control for switching the rotation speed of the rotor (6) to two speeds.

In general, a brushless motor is provided with a frequency dividing circuit for dividing a clock signal supplied from outside to a predetermined frequency when controlling by switching a plurality of rotation speeds. The configuration is such that the frequency division ratio is switched according to the logical value (H or L) of the switching signal to realize a plurality of different rotational speeds.

In the brushless motor (20),
An output of a motor speed detection circuit (9) connected to a frequency generator coil (16) for generating an induction signal having a frequency proportional to the rotation speed of the rotor (6), and a speed switching signal (11)
And a frequency-divided clock signal (12) obtained by dividing the clock signal (10) into different frequency division ratios according to the logical value of the control circuit (1).
4), and the control circuit (14) outputs a speed control signal (13) corresponding to the input to the drive circuit (8). The drive circuit (8) controls the level of the drive current applied to the drive coil (3) according to the input speed control signal (13).

As a result, the rotation speed of the rotor (6) is feedback-controlled, and is controlled to a constant speed in accordance with the frequency of the frequency-divided clock signal (12).

The table shown in FIG. 5 (B) shows that the brushless motor (20) has the following characteristics in accordance with changes in the state of the speed switching signal (11) and the clock signal (10).
It has different control states. That is, the brushless motor (20) is in the stopped state when the clock signal (10) is in the off state and regardless of the logical value of the speed switching signal (11).

When the clock signal (10) is on and the speed switching signal (11) is H (state), the brushless motor (20) has a rotation speed N1 and a clock signal (1).
When (0) is ON and the speed switching signal (11) is L (state), it indicates that the vehicle is controlled at the rotational speed of N2. The frequency of the clock signal (10) is constant at a value fo.

Power is supplied to each circuit and each means included in the configuration shown in FIG. 5A from a power supply (17) outside the brushless motor (20) through a power supply line shown in the figure.

However, it is desired that the brushless motor (20) is rotated when the device on which the motor is mounted requires a rotational driving force, and is stopped and in a standby state when the rotational driving force is unnecessary. Conventionally, even in this standby state, the rotation detecting means (7) and other circuits continue to consume power.

On the other hand, in a brushless motor according to the prior art, a configuration described below which is different from FIG. 5A is also known (not shown).

That is, in the configuration, a drive current level control signal is externally input to the brushless motor, and the magnitude of the drive current flowing through the drive coil is controlled according to the drive current level control signal. It is configured. Such a brushless motor is hereinafter referred to as a current level control type brushless motor.

The current level control type brushless motor also includes rotation detecting means similarly to the above-described brushless motor (20) according to the prior art, and detects the rotation detecting means even in a standby state where the rotor is stopped. Is also consuming unnecessary power.

[0018]

As described above, in the brushless motor according to the prior art, the rotation detecting means continues to consume power even when the rotor (6) is stopped and in the standby mode.

As shown in FIG. 5A, a brushless motor (2) configured to detect rotation using a Hall element is used.
In (0), a large current of, for example, 10 mA continues to flow through the rotation detecting means (7) for driving the Hall element (15). If the brushless motor (20) continues to be operated for a long time, a large electric power is generated. Waste it,
There was a problem.

In particular, when this brushless motor (20) is used as a spindle motor of a floppy disk drive (hereinafter referred to as FDD), the rotor is stopped and waits compared to the time during which the rotor is rotating due to the characteristics of the FDD. Because the time was overwhelmingly long, it consumed a lot of unnecessary power.

When the FDD is driven by a battery, the operable time is shortened by consuming wasteful power, and the increase in wasteful power consumption leads to an increase in CO2 emission in the environment and a global warming. There was a problem that the

In order to solve this problem, it is conceived to provide a configuration in which a power supply management means, which is a new control means, is provided inside the motor, and control is performed to turn on / off the power supply to the rotation detection means (7). Is easy. However, in the case of the above-described configuration, the power management unit needs a new control signal input from outside of the motor in order to determine on / off of the power supply. This will be described below.

First, without using an external signal, rotation / stop of the rotor (6) is determined based on the detection result of the rotation detection means (7) in the motor itself. Consider a configuration that shuts off power to 7). In this configuration, in order to start the rotation again from the stop state, it is necessary to turn on the power of the rotation detecting means (7) to make it detectable (the driving circuit (8) applies the rotating magnetic field to the driving coil (3)). Rotation detection circuit (7)
(6) A rotor (6) position detection signal output from the controller is required), and it is necessary to input some control signal from outside to turn on the power.

This means that, other than the rotation detecting means (7),
For example, using the detection result of the motor speed detection circuit (9),
If the detection result indicates that the rotor (6) is stopped, the power to the rotation detection circuit (7) is cut off.

That is, when the rotation is to be resumed from the standby state (rotor (6) stopped), it is necessary to re-supply the power to the rotation detecting means (7) used for controlling the rotation of the rotor (6) to make full use of it. It is necessary to turn on the power supply to the rotation detecting means (7) by a signal input from the controller.

That is, if it is attempted to turn on / off the power supply to the rotation detecting means (7) in accordance with the rotation / stop of the rotor (6), the spindle motor (2
In (0), it is necessary to newly provide a control signal input from the outside to the motor, and to control on / off of electric power supplied to the rotation detecting means (7) in accordance with a command of the input control signal. there were.

However, in the above configuration, a signal line for a control signal to be newly added is required, so that the number of wirings is increased and the circuit configuration is complicated, and the brushless motor and a device equipped with the brushless motor are increased in size and complexity. There was a problem that the cost was increased.

In the above-described brushless motor of the current level control type, for the purpose of cutting off the supply of power to the rotation detecting means while the rotor (6) is stopped, without increasing the number of wirings inputted from the outside. The level of the drive current indicated by the drive current level control signal is monitored, and when the level falls below a predetermined value, for example, the power supplied to the rotation detecting means when the level is substantially zero is cut off, and the level is reduced to a predetermined level. It is also conceivable to provide a configuration in which power is supplied when the power exceeds the threshold. However, in this configuration, there is a possibility that normal operation control of the motor may be hindered as described below.

That is, with the above configuration, if the rotation of the rotor continues to rotate due to overshoot even though the drive current is substantially zero, it is necessary to detect the rotational position of the rotor. Nevertheless, there was a problem that the power to the rotation detecting means was cut off and detection was not possible.

Similarly, even when the rotor rotates under a light load and the drive current decreases, the power supply to the rotation detecting means is cut off, and the rotational position of the rotor may not be detected.

The present invention has been made in view of the above circumstances, and cuts the power supply to the rotation detecting means (7) while the rotor (6) is stopped without increasing the number of wirings input from the outside. An object of the present invention is to provide a brushless motor that suppresses power consumption and realizes downsizing and cost reduction.

Further, the present invention provides a brushless motor of a current level control type which suppresses power consumption without increasing the number of externally input wires and without hindering normal operation of the motor. That is the purpose of the invention.

[0033]

In order to solve the above-mentioned problems, the invention described in claim 1 of the present application is directed to a “rotor (6) having a magnet (2) magnetized in multiple poles in the circumferential direction. ,
A stator having a multi-phase driving coil (3) facing the magnet (2); rotation detecting means (7) (15) for detecting a rotational position of the rotor (6); and the rotation detecting means (7) A drive circuit (8) that supplies a drive current to the drive coil (3) in accordance with the rotational position of the rotor (6) detected by (15) to generate a rotating magnetic field for rotating the rotor (6); Clock signal (1
In a brushless motor (1a) provided with speed control means (16) (9) for controlling the rotation speed of the rotor (6) by using (9), the cycle or amplitude or duty ratio of the clock signal (19) is A brushless motor (1a) comprising an energization management means (4a) for stopping energization of the rotation detection means (7) (15) accordingly. "I will provide a.

In order to further solve the above-mentioned problem, the invention according to claim 2 of the present application is directed to a “rotor (6) having a magnet (2) magnetized in multiple poles in the circumferential direction; ), A rotation detecting means (7) (15) for detecting a rotational position of the rotor (6), and a rotation detecting means (7).
A drive circuit (8) for generating a rotating magnetic field for rotating the rotor (6) by passing a drive current through the drive coil (3) according to the rotational position of the rotor (6) detected by (15).
And a drive current level control signal (22) input from the outside
A brushless motor (1b) including current level control means (23) for varying the magnitude of the drive current in accordance with the speed, and speed detection means (16) (9) for detecting the rotation speed of the rotor (6). Wherein the level of the driving current indicated by the driving current level control signal (22) is lower than a predetermined value, and the rotation speed of the rotor (6) detected by the speed detecting means (16) (9) is predetermined. A brushless motor (1b) comprising an energization management means (4b) for stopping energization of the rotation detection means (7) (15) when the value is lower than the value. "I will provide a.

In order to further solve the above-mentioned problem, the invention according to claim 3 of the present application is directed to a method for controlling the drive circuit (8) and the power supply management means (4a) (4b) by using a one-chip integrated circuit. 3. The method as claimed in claim 1, wherein
The brushless motors (1a) and (1b) according to (1). "I will provide a.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A brushless motor (1a) according to a first embodiment of the present invention will be described below with reference to FIGS. The same components as those of the brushless motor (20) according to the related art described above are denoted by the same reference numerals, and a description thereof will be partially omitted to avoid repetition.

FIG. 1 is a configuration diagram of a brushless motor (1a) of the present embodiment. In FIG. 1, the brushless motor (1a) is configured as follows.

That is, the brushless motor (1a) comprises a rotor (6) having a magnet (2), a stator having a drive coil (3), a rotation detecting means (7) connected to a Hall element (15), and a drive. A circuit (8) and a motor speed detection circuit (9) to which the frequency generator coil (16) is connected, wherein a mutual relationship between the field magnetic field of the magnet (2) and the rotating magnetic field of the drive coil (3) is provided. The configuration in which a rotational force is generated by the action to rotate the rotor (6) is common to the brushless motor (20) according to the related art described above with reference to FIG.

Further, the brushless motor (1
The characteristic of a) is that it has an energization management means (4a) for managing power supply to the rotation detection means (7) and a control circuit (18) for controlling the rotation speed of the rotor (6).

The power management means (4a) includes a state determination circuit (4a-1), a bias circuit (4a-2), and an electronic switch (4a-3). Operations and functions of these configurations will be described later.

Further, the brushless motor (1
In a), unlike the brushless motor (20) according to the related art described above, a frequency dividing circuit (21) for dividing a clock signal is not included.

Next, the operation and function of the power supply management means (4a) will be described. For this brushless motor (1a),
A clock signal (19) is supplied from outside.

In the brushless motor (20) according to the prior art described above, the clock signal (10) supplied from the outside has a constant and invariable period fo, and the rotor (6)
The clock signal (19) in the present embodiment has a variable frequency, and has a function of varying the rotation speed of the rotor (6) according to the frequency.

Further, the clock signal (19) has a function of changing its cycle, duty ratio or amplitude to control on / off of electric power supplied to the rotation detecting means (7) via the power supply managing means (4a). It has.

The clock signal (19) supplied from outside the motor (1a) is input to the state determination circuit (4a-1). The state determination circuit (4a-1) checks the waveform of the input clock signal (19), determines information indicated by the clock signal (19), and controls the bias circuit (4a-2) according to the determination result. . The detailed operation will be described later.

The bias circuit (4a-2) includes a power supply (17)
And an electronic switch (4a-3) for connecting / disconnecting a power supply line from the power supply line to the rotation detecting means (7).

The above-described configuration is, for example, a clock signal (1
If the period of 9) is longer than the predetermined period, or if the amplitude of the clock signal (19) is smaller than the predetermined amplitude, or if the duty ratio of the clock signal (19) is The power supply to the rotation detecting means (7) can be stopped when the value is larger than a predetermined value. The operation in these configurations will be specifically described with reference to FIGS.

FIG. 2 is a waveform diagram of the clock signal (19) in the present embodiment. FIG. 3 is a circuit diagram of the state determination circuit (4a-1) (FIG. 3A) and a waveform diagram at each point of the state determination circuit (4a-1) (FIG. 3B) in the present embodiment. .

In FIG. 2, (a) -1 to (a) -3
Shows a waveform of the clock signal (19) in a configuration in which power supply to the rotation detecting means (7) is stopped when the cycle of the clock signal (19) is longer than a predetermined cycle.

In FIG. 2 (a) -1, an alternating waveform in which the logical value "H" and the same "L" repeat at a frequency f1, that is, a cycle 1 / f1, is shown in FIG. 2 (a) -2. 2A shows an alternating waveform in which the same "L" repeats at a frequency f2, that is, a period 1 / f2 (f1> f2). FIG. .

When the above three waveforms are input to the point A in the state determination circuit (4a-1) shown in FIG. 3A, integration is performed by the resistor R1 and the capacitor C1.
The average value of the output at point B in (A) is substantially equal to the voltage value obtained by multiplying the duty ratio of the waveform by the power supply voltage Vcc as described below.

2 (a) -1 and 2 (a)
When the waveform shown in FIG. 2 (assuming that the duty ratios of both waveforms are equal as shown) is input to point A, the waveform shown in FIG.
As shown in (b) -1, a triangular waveform having a bias component appears at point B, and its average voltage is V2D. As shown, when the duty ratio of the waveform at point A is 50%, V2D is substantially equal to (1/2) Vcc.

When the waveform shown in FIG. 2 (a) -3 is input to the point A, the waveform appearing at the point B has a voltage value of V2S close to Vcc as shown in FIG. 3 (B) (b) -3. Has a DC waveform.

Further, in FIG. 3A, the comparator (24) included in the state determination circuit (4a-1) determines the magnitude of the voltage value at point B and the threshold value Vt determined by the power supply voltage Vcc and the resistance value in the circuit. And outputs a logical value “H” or “L” to the point C according to the comparison result.

By setting the threshold value Vt so as to satisfy the relationship of V2D <Vt <V2S, as shown in FIGS. 3 (B) (c) -1, FIG. 2 (a) -1 and FIG. 2 (a) -2. 2 (a) is output in response to the input of the waveform (alternating waveform) shown in FIG. 2A, and an "H" value of V3s is output in response to the input of the waveform (DC waveform) shown in FIG. Thus, the comparator (2
4) is configured.

When the output at the point C of the state determination circuit (4a-1) is "H", the bias circuit (4a-2) to which the output value is input is connected to the electronic switch (4a-
3) is cut off, and the power supply to the rotation detecting means (7) is stopped.

When the output at the point C of the state determination circuit (4a-1) is "L", the bias circuit (4a-2) to which the output value is input is connected to the electronic switch (4
a-3) is turned on, and control is performed so that power is supplied to the rotation detecting means (7).

As described above, the brushless motor (1a) controls on / off of power supply to the rotation detecting means (7) (15) according to the length of the cycle of the clock signal (19). Therefore, there is an effect that the brushless motor (1a) which does not consume unnecessary electric power and is environmentally friendly can be configured without adding a new control signal wiring.

FIG. 4 shows an example of an equivalent circuit for realizing the state determination circuit (4a-1) shown in FIG. Points "A", "B" and "C" in FIG.
(A) corresponds to points “A”, “B”, and “C”.

In this embodiment, the clock signal (19) is supplied to the control circuit (1) in addition to the power supply management means (4a).
8) is also branched and input, and is used for controlling the rotation speed of the rotor (6).

That is, when the frequency of the clock signal (19) is f1, the rotation speed of the rotor (6) is N1, and when the frequency is f2, the rotation speed of the rotor (6) is N2. Perform control. The rotation speed of the rotor (6) may be, for example, proportional to the frequency of the clock signal (19).

When the clock frequency (19) has a sufficiently long period and has a substantially DC waveform within a predetermined time, the control circuit (18) stops the rotation of the rotor (6),
Set to the standby mode.

With the above-described configuration, the wiring of the frequency dividing circuit (21) and the speed switching signal (11), which are necessary components in the brushless motor (20) according to the prior art described above, are required. Since the related circuits are not required, the effect of promoting downsizing and cost reduction of the brushless motor is also achieved.

Next, in this embodiment, on / off control of the power supply to the rotation detecting means (7) and the rotor (6) using the cycle of the clock signal (19) in the same manner as described above.
A configuration in which the rotation speed control is performed but the waveform of the clock signal (19) is different from that described above will be described.

FIG. 2B shows waveforms of the clock signal (19) in the configuration. FIG. 2 (b) -1
The waveforms shown in FIG. 2B and FIG. 2B-3 are substantially the same as the waveforms shown in FIG. 2A-1 and FIG. 2A-3 described above, and their operations are the same.

The waveform shown in FIG.
(B) The waveform shown in (-1) lacks one cycle of alternation every six cycles. In this case as well, the threshold value Vt is set so that the energization management means (4a) performs the same control as the waveform of FIG. 2 (b) -1. FIG. 2B-2
Is input, the control circuit (18), for example,
It is configured to control the rotor (6) at a rotation speed proportional to 1 · (5/6).

If the control is performed with the waveforms shown in FIGS. 2B-1, 2 and 3, since the basic clock frequency does not change, the configuration relating to transmission and reception of the clock signal (19) is simpler. There is an effect that can be configured.

Next, FIGS. 2C-1, 2 and 3 show the case where the power supply to the rotation detecting means is stopped when the duty ratio of the clock signal (19) is larger than a predetermined value. It is a waveform of a clock signal (19).

2 (c) -1 and FIG.
When the signal of (c) -2 is input, the motor is operated at a predetermined speed according to the wave number within a certain time. Fig. 2 (c)-
When signals with different duty ratios shown in Fig. 3 are input,
The motor is put into a standby state by the control circuit (18), and the output “C” of the state determination circuit (4a-1) becomes “H”,
The bias circuit (4a-1) is connected to the rotation detecting means (7) (1
Control is performed so as to stop the power supply to 5).

In this case, in order to stabilize the operation,
It is desirable that the above-mentioned threshold value Vt is set to about (1/2) · Vcc. At this time, the control circuit (18)
If the power supply is stopped, no extra operation occurs.

Next, FIGS. 2D-1 to 3D-3 show that the energization of the rotation detecting means (7) and (15) is stopped when the amplitude of the AC component of the clock signal (19) is smaller than a predetermined amplitude. It is a waveform of a clock signal (19) when configured.

FIG. 2D-3 shows an alternating waveform in which the signal repeats at a frequency f1, that is, at a period of 1 / f1, at a level substantially between Vcc and (3/4) Vcc.

In this case, the average value at point B of the state determination circuit (4a-1) integrated by C1 and R1 in FIG. 3A is approximately 7/8 Vcc, and the state determination circuit (4a-1)
Output "C" becomes "H" and the bias circuit (4a-
2) controls to stop the energization of the rotation detecting means (7) (15). At this time, if the control circuit (18) also stops the energization at the same time, no extra operation occurs.

Next, a brushless motor (1b) according to a second embodiment of the present invention will be described with reference to FIG.

FIG. 6 is a configuration diagram of the present embodiment.

In FIG. 6, the brushless motor (1b)
A rotor (6) having a magnet (2), a stator having a drive coil (3), a rotation detecting means (7) to which a Hall element (15) is connected, a drive circuit (8), and a frequency generator And a motor speed detecting circuit (9) connected to the motor coil (16). The motor generates a rotational force by an interaction between a field magnetic field of the magnet (2) and a rotating magnetic field of the driving coil (3). The configuration of rotating (6) is common to the brushless motor (20) according to the related art described above with reference to FIG.

Further, the brushless motor (1
In b), an energization management unit (4b) that manages power supply to the rotation detection unit (7), and a current control unit (23) that controls the magnitude of a drive current flowing through the drive coil (3).
And the power management unit (4b) has a different configuration from the power management unit (4a) described in the first embodiment of the present invention.

The drive current level control signal (22) is externally input to the brushless motor (1b). The drive current level control signal (22) is a DC voltage signal whose voltage is variable, and is branched and input to the current control means (23) and the conduction management means (4b).

The current control means (23) sets the drive current to zero when the drive current level control signal (22) is 1 V or less, so that the drive current increases by 0 A at 1 V and 1 A per 1 V increase at 1 V or more. are doing. For example, when the drive current level control signal (22) is 1.5 V, the voltage is set to 0.
It is configured such that a drive current of 5 A flows.

Further, the power supply management means (4b) includes therein a comparator (4b-1), a NAND circuit (4b-2), and an electronic switch (4b-3).

The comparator (4b-1) outputs a logic "L" when the voltage of the input drive current level control signal (22) is equal to or higher than 1.1 V and a logic "H" when the voltage is lower than 1.1 V. Output the value. Here, the reason why the threshold voltage is obtained by adding the offset voltage 0.1 V instead of 1 V as a threshold value is to ensure the operation even if there is a setting error of the external voltage or a temperature change of the threshold value. Is set to be larger than the sum of the setting error of the external voltage and the temperature change of the threshold value.

On the other hand, the motor speed detection circuit (9) included in the brushless motor (1b) detects the rotation speed of the rotor (6) from the period of the induced voltage induced in the frequency generator coil (16), and detects 100 rpm. A logical value of “L” is output when the above is the case, and a logical value of “H” is output when the speed is less than 100 rpm.

The NAND circuit (4b-2) in the conduction management means (4b), which receives the two logical values from the comparator (4b-1) and the motor speed detection circuit (9), Only when both logical values of the system are "H", the output becomes "L". At that time, the electronic switch (4b-3) is controlled so as to stop energizing the rotation detecting means (7).

Further, the NAND circuit (4b-2)
If the logical value of the system is other than that, the logical value "H" is output, and the electronic switch (4b-3) is controlled so that the rotation detecting means (7) is energized.

The brushless motor (1b) of the present embodiment
Is configured as described above, the rotation detection means (7) despite the fact that rotation detection is necessary because the rotor (6) overshoots or is lightly loaded.
The power supply to the rotation detecting means (7) is stopped by stopping the power supply to the motor, and the possibility of hindering the normal operation of the motor is eliminated. Also, there is an effect of providing a brushless motor (1b) without increasing the number of wirings.

In the first and second embodiments of the present invention described above, the power supply management means (4a) (4
The rotation detecting means (7) for controlling the energization by the component (b) is connected to the Hall element (15), and the magnet (2) in the rotor (6).
It has been described above that the rotational position of the rotor (6) is known from the change in the field magnetic field generated by.

However, in implementing the present invention, the rotation detecting means (7) for turning on / off the power supply need not be limited to the above-described configuration. It is obvious that the method of processing the machine signal to detect the rotational position of the rotor also has the same effect unique to the present invention.

In the first and second embodiments of the present invention described above, the drive circuit (8) and the power supply management means (4a) (4b) may be integrated into the same integrated circuit. Good. With this configuration, the brushless motors (1a) and (1b) can be further reduced in size, cost, and power consumption.

In the description of the first and second embodiments of the present invention, as a method of stopping the power supply to the rotation detecting means (7), the power supply (17) is used to stop the rotation detecting means (7). Electronic switch (4a-3) on the power line
(4b-3) is provided, and the method of controlling conduction and non-conduction according to the logical value inside the conduction management means (4a) (4b) has been described.

However, the practice of the present invention is not limited to the above-described method. For example, while the power line from the power supply (17) to the rotation detecting means (7) is kept conductive, the power management means (4a) (4b) ), A transistor (not shown) constituting the rotation detecting means (7) according to the logical value output
In a cut-off state so that substantially no energization occurs.

With such a configuration, the electronic switch (4a
-3) Since there is no need to use a configuration having a relatively large current capacity of (4b-3), the effect of reducing the voltage drop from the power supply (17) to the rotation detecting means (7) is newly produced.

[0092]

According to the first aspect of the present invention, in the brushless motor (1a), the power supplied to the rotation detecting means (7) according to the cycle or duty ratio or amplitude of the clock signal (19) is turned on / off. Therefore, the power supply to the rotation detecting means (7) (15) while the rotor (6) is stopped is cut by suppressing power consumption without increasing the number of wirings input from the outside. This has the effect of realizing cost reduction.

According to a second aspect of the present invention, in the brushless motor (1b) capable of controlling the level of the driving current, the level of the driving current indicated by the driving current level control signal (22) is lower than a predetermined value, and Speed detection means (9)
When the detected rotation speed of the rotor (6) falls below a predetermined value, the power supply to the rotation detecting means (7) is stopped, so that the number of wirings input from the outside is not increased, and the motor is operated normally. This has the effect of suppressing power consumption and realizing size reduction and cost reduction without hindering operation.

According to the third aspect of the present invention, in addition to the effects of the first or second aspect, the brushless motors (1a) and (1b) are further reduced in size, cost and power consumption. It has the effect of further promoting the conversion.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a brushless motor according to a first embodiment of the present invention.

FIG. 2 is a waveform diagram of a clock signal according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram of a state determination circuit and a waveform diagram at each point according to the first embodiment of the present invention.

FIG. 4 is an example of an equivalent circuit of the state determination circuit according to the first embodiment of the present invention.

FIG. 5 is a configuration diagram of a brushless motor according to the related art and a table for explaining speed setting thereof.

FIG. 6 is a configuration diagram of a brushless motor according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1a brushless motor 1b brushless motor 2 magnet 3 drive coil 4a conduction management means 4b conduction management means 6 rotor 7 rotation detection means 8 drive circuit 9 motor speed detection circuit 10 clock signal 11 speed switching signal 12 frequency division clock signal 13 speed control signal 14 Control circuit 15 Hall element 16 Frequency generator coil 17 Power supply 18 Control circuit 19 Clock signal 20 Brushless motor 21 Divider circuit 22 Drive current level control signal 23 Current control means 24 Comparator

Claims (3)

[Claims] 1. A rotor having a magnet multipolarized in the circumferential direction, a stator having a multi-phase drive coil facing the magnet, rotation detecting means for detecting a rotational position of the rotor, and the rotation. A drive circuit that supplies a drive current to the drive coil in accordance with the rotation position of the rotor detected by the detection means and generates a rotation magnetic field for rotating the rotor; and a rotation speed of the rotor using a clock signal input from outside. A brushless motor provided with speed control means for controlling the rotation of said clock signal, comprising: a power supply management means for stopping power supply to said rotation detecting means in accordance with a cycle or an amplitude or a duty ratio of said clock signal. . 2. A rotor having a magnet which is magnetized to have multiple poles in a circumferential direction; a stator having a multi-phase drive coil facing the magnet; rotation detecting means for detecting a rotational position of the rotor; A drive circuit for supplying a drive current to the drive coil in accordance with the rotational position of the rotor detected by the detection means to generate a rotating magnetic field for rotating the rotor; and a drive current in response to a drive current level control signal input from outside. In a brushless motor comprising: a current level control unit that varies the magnitude of the motor; and a speed detection unit that detects a rotation speed of the rotor, the level of the precursor drive current indicated by the drive current level control signal falls below a predetermined value. And when the rotation speed of the rotor detected by the speed detection means is lower than a predetermined value, the power supply to the rotation detection means is stopped. Brushless motor, comprising the management unit. 3. The control circuit according to claim 1, wherein
2. The integrated circuit according to claim 1, wherein the integrated circuit is integrated on a chip.
Or a brushless motor according to claim 2.