JP2016220521A - Motor drive circuit, driving method, vibration device, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress reverse rotation of a rotor with reverse braking.SOLUTION: A controller 110 generates a drive signal S3 for controlling energization to a coil of a motor 2 to be driven on the basis of a rectangular signal S2 representing a position of a rotor of the motor 2. A drive unit 130 drives the coil on the basis of the drive signal S3. The controller 110 monitors a period of the rectangular signal S2 during reverse braking, and, when the period becomes short, the reverse braking is terminated.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a motor driving technique.

  In a driver for a brushless motor, a brake function may be mounted in order to stop a normally rotating rotor. There are regenerative brakes and reverse brakes. In regenerative braking, a loop is formed by the output stage of the driver and the motor coil, and current is passed through the loop to dissipate the energy of the motor coil.

  When it is desired to stop the rotor with a braking force stronger than that of the regenerative brake, a reverse brake is employed. In the reverse brake, the motor coil is driven so that torque is generated in the rotor in the opposite phase to the normal drive state (forward rotation state), in other words, in the reverse direction to the forward rotation direction.

JP 2006-234208 A JP 2009-018654 A Japanese Patent Laid-Open No. 8-191591

Problem 1. The present inventors examined the following reverse brake control (referred to as a study technique).

  The study technique monitors the period of the hall signal during reverse braking. When the cycle exceeds a predetermined threshold value, it is assumed that the rotor has sufficiently decelerated, and the reverse brake is terminated.

  When the brushless motor is controlled in synchronization with the Hall signal from the Hall element, the minimum reverse brake time is restricted by the period of the Hall signal. Therefore, when the torque of the rotor in the forward rotation direction immediately before the reverse rotation brake is small, the torque applied to the rotor by the reverse rotation brake for a certain minimum time or more may exceed, and the rotor may reversely rotate.

  If the period of the Hall signal exceeds the threshold immediately after starting reverse rotation, the reverse brake termination condition is not satisfied, the reverse brake cannot be released, and the rotor may be further accelerated in the reverse direction. .

Problem 2 Furthermore, as a result of examining the reverse brake, the present inventors have recognized the following problems. When the brushless motor is controlled in synchronization with the Hall signal from the Hall element, the minimum reverse brake time is restricted by the period of the Hall signal. Therefore, when the torque of the rotor in the forward rotation direction immediately before the reverse rotation brake is small, the torque applied to the rotor by the reverse rotation brake for a certain minimum time or more may exceed, and the rotor may reversely rotate. This problem should not be regarded as a general recognition of those skilled in the art.

  An aspect of the present invention has been made in view of any of the above-described problems, and one of exemplary purposes thereof is a motor drive circuit capable of preventing, suppressing, or preventing reverse rotation of the rotor due to reverse brake. On offer.

1. One embodiment of the present invention relates to a motor drive circuit. The motor drive circuit includes a control unit that generates a drive signal for controlling energization of the motor coil based on a rectangular signal indicating the position of the rotor of the motor to be driven, and a drive unit that drives the coil based on the drive signal. . The control unit monitors the period of the rectangular signal during the reverse brake period, and ends the reverse brake when the period becomes shorter.

  According to this aspect, it is possible to immediately detect the rotation of the rotor in the reverse direction based on the relative change in the cycle indicating the rotation speed of the rotor, thereby suppressing the reverse rotation of the rotor due to the reverse brake.

  The control unit may end the reverse brake based on the magnitude relationship between the current cycle and the past cycle.

When the current period is T _CUR , the past period is T _PRE , and a correction value of 0 or more is T _CORR ,
T _CUR + T _CORR ≦ T _PRE
The reverse brake may be terminated when the condition is satisfied.

When the current cycle is T _CUR and the past cycle is T _PRE , the control unit T _CUR <T _PRE
The reverse brake may be terminated when the condition is satisfied.

  The past cycle may be a cycle measured once before. The past cycle may be based on a plurality of cycles measured over the most recent predetermined number of times.

  The controller may end the reverse brake when the period of the rectangular signal becomes longer than a predetermined threshold during the reverse brake period. The control unit may include an edge counter that measures the number of edges of the rectangular signal during the reverse brake period, and the reverse brake may be terminated when the count value of the edge counter exceeds a predetermined threshold value. The control unit may include a timer circuit that measures the length of the reverse brake period, and the reverse brake may be terminated when the reverse brake period reaches a predetermined time. A plurality of reverse brake termination conditions may be combined.

2. Another aspect of the present invention relates to a motor drive circuit. The motor drive circuit includes a control unit that generates a drive signal for controlling energization to the coil of the motor based on a rectangular signal indicating the position of the rotor of the motor to be driven, a hall comparator that generates a rectangular signal, and a rectangular signal A control unit that controls energization of the coil of the motor based on the drive unit, and a drive unit that drives the coil based on a drive signal from the control unit. When receiving a motor stop instruction in the normal driving state of the motor, the control unit applies a reverse brake with an output corresponding to the normal driving state up to that time.

  In one aspect, the control unit can estimate how much torque the motor rotor has in the forward rotation direction by monitoring the normal driving state before applying the reverse brake. Therefore, when it is estimated that the rotor has a sufficiently large torque in the forward direction, the reverse brake is applied with a large output, and when the torque in the forward direction is estimated to be small, the reverse brake The output is reduced, or the output is zero, that is, the reverse brake is not applied, so that the rotor can be prevented from rotating in the reverse direction.

In one aspect, the control unit may change the output of the reverse brake in accordance with the number of switching of the rectangular signal generated in the normal driving state.
If the number of level transitions of the rectangular signal is small, it can be estimated that the torque in the forward direction of the rotor is small, and the output of the reverse brake can be reduced.

  In one aspect, the control unit may include an edge counter that measures the number of edges of the rectangular signal in the normal driving state, and may change the output of the reverse brake according to the count value of the edge counter.

  In a certain aspect, when the control unit receives an instruction to stop the motor, when the number of edges of the rectangular signal measured so far is smaller than a predetermined threshold value, the output of the reverse brake is reduced compared to when it is large. You may let them.

  In one aspect, the control unit does not need to apply the reverse brake when the motor stop instruction is received and the number of edges of the rectangular signal measured so far is smaller than a predetermined threshold value.

In one aspect, the control unit may change the output of the reverse brake according to the length of the normal drive state.
If the normal driving state is short, it can be estimated that the torque in the forward direction of the rotor is small, and the output of the reverse brake can be reduced.

  In one aspect, the control unit may include a timer circuit that measures the length of the normal driving state, and may change the output of the reverse brake according to the measurement time of the timer circuit.

  In a certain aspect, the control unit may reduce the output of the reverse brake when the measurement time is shorter than a predetermined threshold when the motor stop instruction is received, compared to when the measurement time is longer.

  In a certain aspect, the control unit does not have to apply the reverse brake when the measurement time is shorter than the predetermined threshold when receiving the instruction to stop the motor.

  The controller may end the reverse brake when the period of the rectangular signal becomes longer than a predetermined threshold during the reverse brake period. The control unit may include an edge counter that measures the number of edges of the rectangular signal during the reverse brake period, and the reverse brake may be terminated when the count value of the edge counter exceeds a predetermined threshold value. The control unit may include a timer circuit that measures the length of the reverse brake period, and the reverse brake may be terminated when the reverse brake period reaches a predetermined time. A plurality of reverse brake termination conditions may be combined.

In one embodiment, the motor drive circuit may be integrated on a single semiconductor substrate.
“Integrated integration” includes the case where all of the circuit components are formed on a semiconductor substrate and the case where the main components of the circuit are integrated. A resistor, a capacitor, or the like may be provided outside the semiconductor substrate.
By integrating the circuit on one chip, the circuit area can be reduced and the characteristics of the circuit elements can be kept uniform.

  Another embodiment of the present invention relates to a vibration device. The vibration device may include a vibration motor having an eccentric weight attached to a rotor, and a motor drive circuit that rotates the vibration motor.

  Another embodiment of the present invention relates to an electronic device. The electronic device may include the above-described vibration device.

  Note that any combination of the above-described constituent elements and the constituent elements and expressions of the present invention replaced with each other among methods, apparatuses, systems, and the like are also effective as an aspect of the present invention.

  According to an aspect of the present invention, it is possible to suppress or prevent reverse rotation of the rotor accompanying reverse brake.

It is a block diagram of the motor drive circuit concerning a 1st embodiment. It is a block diagram which shows the specific structural example of a motor drive circuit. 3A and 3B are operation waveform diagrams of the motor drive circuit of FIG. It is a block diagram which shows the structural example of a reverse brake control part. It is a block diagram of the reverse brake control part which concerns on a 2nd modification. It is a block diagram of the motor drive circuit which concerns on 1st Example of 2nd Embodiment. 7A and 7B are operation waveform diagrams of the motor drive circuit of FIG. It is a block diagram of the motor drive circuit which concerns on 2nd Example. 9A and 9B are operation waveform diagrams of the motor drive circuit of FIG. FIG. 10A is a perspective view of an electronic device including a motor drive circuit, and FIG. 10B is a cross-sectional view of the vibration motor unit. It is a perspective view of an electronic device provided with a motor drive circuit.

  The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent components, members, and processes shown in the drawings are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate. The embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

In this specification, “the state in which the member A is connected to the member B” means that the member A and the member B are electrically connected to each other in addition to the case where the member A and the member B are physically directly connected. It includes cases where the connection is indirectly made through other members that do not substantially affect the general connection state, or that do not impair the functions and effects achieved by their combination.
Similarly, “the state in which the member C is provided between the member A and the member B” refers to the case where the member A and the member C or the member B and the member C are directly connected, as well as their electric It includes cases where the connection is indirectly made through other members that do not substantially affect the general connection state, or that do not impair the functions and effects achieved by their combination.

(First embodiment)
FIG. 1 is a block diagram of a motor drive circuit 100 according to the first embodiment. The motor drive circuit 100 drives a single-phase brushless motor (hereinafter simply referred to as a motor) 2. The hall element 4 generates a pair of hall signals H + and H− according to the position of the rotor of the motor 2. The hall signals H + and H− are out of phase with each other.

  The motor drive circuit 100 receives a control command S1 for instructing rotation / stop of the motor 2 from a host processor (not shown). When the hall signals H + and H− are input to the motor drive circuit 100 and the control command S1 instructs rotation, the coil of the motor 2 is energized in synchronization with the hall signals H + and H−.

  The motor driving circuit 100 includes a Hall comparator 102, a control unit 110, and a driving unit 130, and is a functional IC (Integrated Circuit) integrated on a single semiconductor substrate. The Hall comparator 102 compares the Hall signals H + and H− from the Hall element 4 and generates a rectangular signal (also referred to as FG signal) S2. The control unit 110 generates a drive signal S3 that controls energization of the coil of the motor 2 based on the rectangular signal S2. The drive unit 130 drives the coil based on the drive signal S3 from the control unit 110. The configuration of the drive unit 130 is not particularly limited, and a known circuit may be used.

A control command S1 for instructing rotation / stop of the motor 2 is input to the control unit 110. When receiving a stop instruction for the motor 2 in the normal driving state in which the motor 2 is rotated in a certain direction (normal rotation direction), the control unit 110 applies a reverse brake. Control unit 110, during the reverse rotation brake, Hall signals H +, the period of H-, namely to monitor the period T _P of the rectangular signal S2 _(a half period in the present embodiment), when the period T _P becomes shorter, End reverse brake.

  The control unit 110 includes an energization control unit 112 and a reverse brake control unit 114. The energization control unit 112 performs commutation control synchronized with the rectangular signal S2. The reverse brake control unit 114 controls the end of the reverse brake.

Reverse brake control unit 114 specifically, the duration of the reverse brake, measures the period _{T P} of the rectangular signal S2, compared to the current period _{T CUR} and past period _{T PRE,} the present period _{T CUR} past When the period becomes shorter than the period _TPRE , the reverse brake is terminated. This is the first condition. The past cycle T _PRE may be the immediately preceding cycle T _P. Alternatively, the past period T _PRE may be a value calculated from a plurality of periods T _P measured over a plurality of past cycles. For example, the past cycle T _PRE may be a simple average or a moving average of a plurality of past cycles T _P.

The reverse brake control unit 114 ends the reverse brake when a predetermined time _TEND has elapsed after the reverse brake is started. This is the second condition. The reverse brake control unit 114 ends the reverse brake when either the first condition or the second condition is satisfied.

  The invention related to the first embodiment is understood as the block diagram and circuit diagram of FIG. 1 or extends to various devices and circuits derived from the above description, and is limited to a specific configuration. is not. Hereinafter, more specific configuration examples will be described in order not to narrow the scope of the present invention but to help understanding and clarify the essence and circuit operation of the present invention.

  FIG. 2 is a block diagram illustrating a specific configuration example of the motor drive circuit 100. The reverse brake control unit 114 includes a period measurement unit 118 and a determination unit 120. The period measuring unit 118 measures the period of the rectangular signal S2 (the length of each of the high level section and the low level section, that is, a half period), and outputs data (period data) S5 indicating the measured period to the determination unit 120. .

The determination unit 120 compares the current cycle T _CUR indicated by the cycle data S5 with the past cycle T _PRE held in the memory, and when the magnitude relationship satisfies a predetermined condition (first condition), the end signal S7 Is asserted (eg, high level). The determination unit 120 asserts an end signal S7 when a predetermined time _TEND elapses after the reverse brake is started. The energization control unit 112 ends the reverse brake when the end signal S7 is asserted.

  Next, the operation of the motor drive circuit 100 will be described. 3A and 3B are operation waveform diagrams of the motor drive circuit 100 of FIG. First, with reference to FIG. 3A, the end of the reverse rotation brake according to the second condition will be described. At time t0, the control command S1 becomes a high level instructing rotation. As a result, the control unit 110 starts energizing the motor 2. As the rotation speed of the motor 2 increases, the cycle of the rectangular signal S2 becomes shorter.

When the control command S1 becomes a low level instructing to stop at time t1, the energization control unit 112 starts reverse brake. The rotor is decelerated by the reverse brake, and the cycle of the rectangular signal S2 becomes longer. Then from time t1 to the time t2 after a predetermined time _{T END} course, termination signal S7 is asserted, reverse braking is terminated.

  Next, with reference to FIG. 3B, the end of the reverse rotation brake according to the first condition will be described. At time t0, the control command S1 becomes a high level instructing rotation. As a result, the control unit 110 starts energizing the motor 2. Immediately after that, at time t3, before the rotational speed of the motor 2 increases, the control command S1 becomes a low level, the stop of the motor 2 is instructed, and the energization control unit 112 starts reverse braking.

The period measuring unit 118 measures the periods T _P0 , T _P1 , T _P2 , T _P3 ... Of the rectangular signal S2 for each cycle. In the i-th cycle, the current period T _CUR (= T _Pi ) is compared with the past period T _PRE (= T _Pi−1 ). Here, it is assumed that the past cycle T _PRE is the cycle T _P of the immediately preceding cycle.

In the period Ta immediately after the start of the reverse brake, T _Pi > T _Pi−1 is established. That is, the period of the rectangular signal S2 is gradually increased, and the rotor is decelerated. When T _P3 > T _P2 is detected at time t4 and the first condition is satisfied, the end signal S7 is asserted and the reverse brake is ended.

The above is the operation of the motor drive circuit 100. If the reverse brake is continuously applied after a short normal drive, the rotor is accelerated in the reverse direction. On the other hand, according to the motor drive circuit 100 according to the first embodiment, by measuring the period T _P of the rectangular signal S2, the T _{CUR <T PRE} is detected, the rotor is inverted into the opposite direction The reverse brake can be stopped immediately.

FIG. 4 is a block diagram illustrating a configuration example of the reverse brake control unit 114. The determination unit 120 includes a first determination unit 120a and a second determination unit 120b that determine the first condition and the second condition, respectively. The second determination unit 120b includes a timer circuit 160 measures the time elapsed after the start of reverse rotation brake, after a predetermined time _{T END} elapsed, asserts an end signal S7b. The predetermined time _TEND is set based on the value of the register 162 at a predetermined address. The predetermined time T _END is preferably settable from an external host processor via an interface such as an I ² C (Inter IC) bus.

The first determination unit 120a includes a memory 150, a comparator 152, an adder 154, and a register 156. The memory 150 holds the past cycle T _PRE . As described above, the past cycle T _PRE may be the immediately preceding cycle T _P or may be an average value of a plurality of past cycles T _P.

And mounting position of the Hall element, the variation of the magnetic field, when the rotor is rotating at a constant speed, the period T _P of the rectangular signal S2 not constant, may vary. This means that the reverse rotation of the rotor can be erroneously detected when the current cycle T _Pi and the previous cycle T _Pi-1 are simply compared. In order to prevent such erroneous detection, the first determination unit 120a corrects the cycle _TCUR .

The adder 154 adds the correction value _{T CORR} in the current period _{T CUR,} to produce a corrected period _{T CUR} '. The correction value T _CORR is 0 or more (≧ 0), and is set based on the value of the register 156 at a predetermined address. The predetermined value T _CORR is preferably settable from an external host processor via an interface such as an I ² C (Inter IC) bus. The optimum value of the correction value T _CORR may be determined according to the type of motor 2, the number of poles, the load connected to the rotor, the moment of inertia, and the like.

The comparator 152 compares the corrected current period T _CUR ′ with the past period T _PRE ,
T _CUR '≦ T _PRE
When satisfying, in other words, T _CUR + T _CORR ≦ T _PRE
When the condition is satisfied, the end signal S7a is asserted.

  The logic gate 164 asserts the end signal S7 when at least one of the end signals S7a and S7b is asserted. For example, logic gate 164 may be composed of an OR gate.

According to the reverse brake control unit 114, the sensitivity of the reverse _rotation detection of the rotor can be adjusted according to the correction value T _CORR . By making it possible to set the correction value T _CORR from the outside using the register 156, it is possible to realize optimal control for the platform on which the motor drive circuit 100 is used.

  As described above, a certain aspect of the present invention has been described based on the first embodiment. The first embodiment is an exemplification, and it is understood by those skilled in the art that various modifications can be made to the combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. It is a place. Hereinafter, such modifications will be described.

(First modification)
In FIG. 4, the current cycle T _CUR is corrected, but the past cycle T _PRE may be corrected. In this case, the correction value T _CORR may be subtracted from the value read from the memory 150 to generate a corrected period T _PRE ′, and T _PRE and T _CUR may be compared.

(Second modification)
In the first embodiment, the reverse brake is terminated when a predetermined time _TEND elapses after the reverse brake is started. However, the present invention is not limited to this. FIG. 5 is a block diagram of the reverse brake control unit 114a according to the second modification. In the second modification, the second condition may be that the number of times of switching (the number of edges) of the rectangular signal S2 generated during the reverse brake period exceeds a threshold value.

The second determination unit 120b includes an edge counter 170, a comparator 172, and a register 174. The edge counter 170 counts the number of edges of the rectangular signal S2 after the reverse brake is started. The comparator 172 compares the count value S4 of the edge counter 170 with a predetermined threshold value D, and asserts an end signal S7b when S4> D. The threshold value D is set based on the value of the register 174 at a predetermined address. The threshold D is preferably settable from an external host processor via an interface such as an I ² C (Inter IC) bus.

(Third Modification)
In the first embodiment, the reverse brake is terminated when either the first condition or the second condition is satisfied, but the second condition may be omitted. In this case, the timer circuit 160 and the logic gate 164 of FIG. 4 may be omitted.

(Fourth modification)
In the first embodiment, the reverse brake is terminated based on the magnitude relationship between the current cycle T _CUR and the past cycle T _PRE , but the present invention is not limited to this. For example, paying attention to a plurality of consecutive (for example, three or more) cycles, the reverse brake may be terminated when a shortening tendency is seen in the cycle.

(5th modification)
The Hall comparator 102 may be built in the Hall IC including the Hall element 4. Alternatively, the Hall element 4 may be built in the motor drive circuit 100.

(Sixth Modification)
In the first embodiment, the motor drive circuit 100 that performs the commutation control using the Hall signal from the Hall element and controls the reverse rotation prevention has been described. You may use the signal containing rotation speed information.

(Second Embodiment)
A second embodiment will be described with reference to FIG. Since the basic configuration is the same as that of the first embodiment, the description regarding the common points is omitted, and the differences will be described.

  A control command S1 for instructing rotation / stop of the motor 2 is input to the control unit 110. When the control unit 110 receives an instruction to stop the motor 2 in the normal driving state in which the motor 2 is rotated in a certain direction (forward rotation direction), the control unit 110 performs reverse braking with an output according to the normal driving state up to that point. Multiply.

  The control unit 110 includes an energization control unit 112 and a reverse brake control unit 114. The energization control unit 112 performs commutation control synchronized with the rectangular signal S2. The reverse brake control unit 114 controls the output of the reverse brake. Specifically, the reverse brake control unit 114 changes the output of the reverse brake based on the normal drive state before the reverse brake is applied. When the motor drive circuit 100 performs PWM control, the reverse brake control unit 114 can change the duty ratio of the drive voltage Vo + / Vo− applied to the motor 2 to change the output of the reverse brake.

The above is the configuration of the motor drive circuit 100 in the second embodiment. Next, the operation will be described.
While the control command S1 instructs the rotation of the rotor, the energization control unit 112 performs commutation control based on the rectangular signal S2, and supplies the motor 2 with the drive voltage Vo + / Vo− having a duty ratio corresponding to the target rotational speed. Supply. The duty ratio in the normal driving state may be a fixed value or 100%.

  The reverse brake control unit 114 monitors the normal drive state. The reverse brake control unit 114 can estimate how much torque the rotor of the motor 2 has in the forward rotation direction based on the monitoring result. Therefore, if it is estimated that the rotor has a sufficiently large torque in the forward rotation direction, the reverse brake is applied with a large output (rated output), and the torque in the forward rotation direction is estimated to be small. The reverse brake is reduced below the rated output, or the output is zero, that is, the reverse brake is not applied.

  Thereby, it is possible to prevent the reverse torque applied to the rotor by the reverse brake from exceeding the forward torque applied to the normal drive state, and to prevent the rotor from rotating backward.

  The invention related to the second embodiment is understood as the block diagram and circuit diagram of FIG. 1 or extends to various devices and circuits derived from the above description, and is limited to a specific configuration. is not. Hereinafter, more specific configuration examples will be described in order not to narrow the scope of the present invention but to help understanding and clarify the essence and circuit operation of the present invention.

FIG. 6 is a block diagram of the motor drive circuit 100a according to the first example of the second embodiment.
The reverse brake control unit 114a of the motor drive circuit 100a changes the output of the reverse brake according to the number of times of switching of the rectangular signal S2 generated in the normal drive state. The reverse brake control unit 114 a includes an edge counter 116, a period measurement unit 118, and a drive unit 130. The edge counter 116 measures the number of edges of the rectangular signal S2 in the normal driving state. The determination unit 120 changes the output of the reverse brake according to the count value S4 of the edge counter 116.

  For example, when the control command S1 instructs the motor to stop, the control unit 110 (determination unit 120) sets the count value S4 indicating the number of edges of the rectangular signal S2 counted so far to a predetermined threshold value A. If larger, apply reverse brake at rated output. For example, the rated output may be a duty ratio in the range of 70 to 100%.

  For example, the threshold value A may be determined so that the rotor is not more than one rotation (360 ° in mechanical angle). For example, in a 3-pole brushless motor, the edge of the rectangular signal S2 is generated 6 times in one rotation of the rotor, and is generated 3 times in half rotation. Therefore, A may be about 3 to 6. In the two-pole brushless motor, the edge of the rectangular signal S2 is generated twice in one rotation of the rotor, and is generated once in half rotation.

  The threshold A may be determined according to the type and number of poles of the motor 2, the load connected to the rotor, the moment of inertia, and the like, and may be about 1 to 20.

  Conversely, the control unit 110 (determination unit 120) (ii) reduces the output of the reverse brake from the rated output when the number of edges of the rectangular signal S2 counted so far is smaller than the predetermined threshold A. In the present embodiment, the control unit 110 does not apply the reverse brake when the number of edges of the measured rectangular signal is smaller than the predetermined threshold A. That is, the output of the reverse brake is set to 0% duty ratio.

  The period measurement unit 118 measures the period of the rectangular signal S2 (the length of each of the high-level section and the low-level section, that is, a half period) while applying reverse braking, and obtains data (period data) S5 indicating the measured period. Output to the determination unit 120. When the period indicated by the period data S5 is longer than the predetermined threshold value B, the determination unit 120 ends the reverse brake.

  The threshold A is desirably settable according to setting data stored in a register at a certain address. Similarly, it is desirable that the threshold value B can be set according to setting data stored in a register at a certain address. Since these thresholds A and B have different optimum values depending on the type, polarity, and application of the motor 2, it is possible for a designer of a device on which the motor drive circuit 100 is mounted to select the thresholds A and B. This makes it possible to achieve optimal control for various platforms.

The above is the configuration of the motor drive circuit 100a. Next, the operation will be described.
FIGS. 7A and 7B are operation waveform diagrams of the motor drive circuit 100a of FIG. The vertical axis and horizontal axis of the waveform diagrams and time charts in this specification are appropriately expanded and reduced for easy understanding, and each waveform shown is also simplified for easy understanding. Or it is exaggerated or emphasized.

  Reference is made to FIG. At time t0, the control command S1 becomes a high level instructing rotation. As a result, the control unit 110 starts energizing the motor 2. As the rotation speed of the motor 2 increases, the cycle of the rectangular signal S2 becomes shorter. The count value S4 increases with the rotation of the motor 2, and reaches the upper limit value N of the edge counter 116 at time t1.

At time t2, the control command S1 becomes a low level instructing the stop. Since N> A at time t2, reverse brake is applied at the rated output. The rotor is decelerated by the reverse brake, and the cycle of the rectangular signal S2 becomes longer. At time t3, the period T _P of the rectangular signal S2 exceeds the threshold B, reverse braking period ends.

  Reference is made to FIG. At time t0, the control command S1 becomes a high level instructing rotation. As a result, the control unit 110 starts energizing the motor 2. At time t1 immediately after that, the control command S1 becomes a low level before the rotation speed of the motor 2 increases, and the stop of the motor 2 is instructed.

  At time t1, the edge count value S4 is 2, which is smaller than the threshold value A (for example, 3). Therefore, without applying the reverse brake, the rotor is stopped by the regenerative brake, or the rotor is naturally stopped.

The above is the operation of the motor drive circuit 100a. In FIG. 7B, the torque in the forward direction of the motor at time t1 is very small. Therefore, if the reverse brake is applied when the control command S1 becomes low level, the rotor starts to rotate in the reverse direction. Then immediately after starting to rotate in opposite directions, if the period T _P of the rectangular signal S2 is shorter than the threshold value B, mired reverse brake, which may further accelerate the rotor in the opposite direction.

  On the other hand, according to the motor drive circuit 100a of FIG. 6, when the number of edges of the rectangular signal S2 measured in the normal drive state is smaller than the threshold value A, the torque in the forward rotation direction is sufficiently small. It is possible to prevent the reverse rotation of the rotor by presuming that the brake is not applied and applying the reverse brake.

  Further, the first embodiment has the following advantages over the second embodiment described below. In the second embodiment, based on the length of the normal driving state, the rotational state in the forward rotation direction of the motor is estimated, and whether or not the reverse brake should be applied is switched. However, an abnormality such as a foreign object caught in the rotor has occurred. Sometimes, even if the length of the normal driving state is sufficiently long, the torque in the forward rotation direction is small, and the reverse rotation brake may cause the rotor to reverse. On the other hand, if the number of edges of the rectangular signal S2 is larger than the threshold value A, it is the basis that the motor is reliably rotating in the forward rotation direction. Can be prevented.

FIG. 8 is a block diagram of a motor drive circuit 100b according to the second embodiment.
The reverse brake control unit 114b of the motor drive circuit 100b changes the output of the reverse brake according to the length of the normal drive state. The reverse brake control unit 114b includes a timer circuit 122 instead of the edge counter 116 of FIG. The timer circuit 122 measures the length in the normal driving state, and generates section length data S6 indicating the measured length. The timer circuit 122 may be a digital timer that counts up (or counts down) the clock signal during the normal driving state. In another embodiment, the timer circuit 122 may be an analog timer. The determination unit 120 changes the output of the reverse brake according to the measurement time of the timer circuit 122.

  For example, when the measurement time of the timer circuit 122 exceeds a predetermined threshold C, the determination unit 120 applies reverse braking at the rated output, and when the stop is instructed in a state where the measurement time is shorter than the threshold C, Do not apply reverse brake or reduce reverse brake output.

The above is the configuration of the motor drive circuit 100b in FIG. Next, the operation will be described.
9A and 9B are operation waveform diagrams of the motor drive circuit 100b in FIG. Reference is made to FIG. At time t0, the control command S1 becomes a high level instructing rotation. As a result, the control unit 110 starts energizing the motor 2. As the rotation speed of the motor 2 increases, the cycle of the rectangular signal S2 becomes shorter. The section length data S6 indicating the length of the normal driving state increases with time. Since the bit width of the timer circuit 122 is finite, the count-up is stopped when the section length data S6 reaches a certain upper limit value.

At time t2, the control command S1 becomes a low level instructing the stop. At time t2, since S6> C, the reverse brake is applied at the rated output. The rotor is decelerated by the reverse brake, and the cycle of the rectangular signal S2 becomes longer. At time t3, the period T _P of the rectangular signal S2 exceeds the threshold B, reverse braking period ends.

  Reference is made to FIG. At time t0, the control command S1 becomes a high level instructing rotation. As a result, the control unit 110 starts energizing the motor 2. At time t1 immediately after that, the control command S1 becomes a low level before the rotation speed of the motor 2 increases, and the stop of the motor 2 is instructed.

  At time t1, the section length data S6 is smaller than the threshold value C. Therefore, without applying the reverse brake, the rotor is stopped by the regenerative brake, or the rotor is naturally stopped.

  The above is the operation of the motor drive circuit 100b. The same effect as the motor drive circuit 100a of FIG. 6 can be obtained by the motor drive circuit 100b.

  As described above, an aspect of the present invention has been described based on the second embodiment. The second embodiment is an exemplification, and it is understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. It is a place. Hereinafter, such modifications will be described.

(Seventh Modification)
In the second embodiment, the output of the reverse brake is set to zero when there is a possibility of reverse rotation, but the present invention is not limited to this. For example, when there is a possibility of reversal, the output of the reverse brake may be a value larger than zero and smaller than the rated output, for example, about 5 to 30%.

(Eighth modification)
Alternatively, the output of the reverse brake when there is a possibility of reverse may be adaptively changed according to the previous normal driving state. For example, the smaller the number of edges of the rectangular signal S2 measured in the normal drive state, the lower the reverse brake output may be, or the shorter the normal drive state length, the lower the reverse brake output. Also good.

(Ninth Modification)
In the second embodiment, the period T _P of the rectangular signal S2 exceeds the threshold B, and to complete the reverse brake period is not the invention limited thereto. In the ninth modified example, the reverse brake is terminated when the number of switching (number of edges) of the rectangular signal S2 generated during the reverse brake period exceeds a threshold value. When the ninth modification is applied to the first embodiment of FIG. 6, the edge counter 116 can be used to count the number of edges of the rectangular signal S2 during the reverse braking period. When the number S4 of edges generated during the reverse brake exceeds the threshold value D, the determination unit 120 ends the reverse brake.

  When the ninth modification is applied to the second embodiment of FIG. 8, an edge counter 116 may be added to the reverse brake control unit 114b.

(10th modification)
In the tenth modification, when the length of the reverse brake period reaches a predetermined time _TEND , the reverse brake is terminated. When the tenth modification is applied to the second embodiment of FIG. 8, the timer circuit 122 may be used to measure the length of the reverse brake period. The determination unit 120 compares the reverse brake period measured by the timer circuit 122 with a predetermined time _TEND .

  When the tenth modification is applied to the first embodiment of FIG. 6, a timer circuit 122 may be added to the reverse brake control unit 114a.

(Eleventh modification)
The Hall comparator 102 may be built in the Hall IC including the Hall element 4. Alternatively, the Hall element 4 may be built in the motor drive circuit 100.

(Twelfth modification)
In the second embodiment, the motor drive circuit 100 that performs the commutation control using the Hall signal from the Hall element and controls the reverse rotation has been described. However, instead of the Hall element to the Hall signal, other than that, You may use the signal containing rotation speed information.

  Any feature of the first embodiment and any feature of the second embodiment can be combined, and the combination is also effective as one aspect of the invention.

(Use)
Next, the application of the motor drive circuit 100 described in the first or second embodiment will be described. FIG. 10A is a perspective view of an electronic apparatus 300a including the motor drive circuit 100, and FIG. 10B is a cross-sectional view of the vibration motor unit.

  The electronic device 300 is a device having a vibration function, and examples thereof include a mobile phone terminal, a smart phone, a tablet PC, a mobile game device, a game console controller, and the like. FIG. 10A shows a smart phone as a representative.

  The electronic device 300 includes a vibration device 302 and a host processor 304. The vibration device 302 is a vibration motor unit in which the motor 2 and the motor drive circuit 100 are integrally formed and covered with a cover. As shown in FIG. 10B, the motor drive circuit 100 and the coil 312 are mounted on the substrate 310. A washer 314 is attached to the shaft 316 and is rotatably supported. A rotor 318 having an eccentric weight 318a and a permanent magnet 318b embedded in the inner periphery thereof is attached to the tip of the shaft 316. The entire vibration device 302 is covered with a cover 320.

  The motor drive circuit 100 rotates the motor 2 in response to the control command S1 from the host processor 304. The host processor 304 can be a baseband processor or an application processor.

  FIG. 11 is a perspective view of an electronic apparatus 300b having another configuration. An eccentric weight 306 is attached to the rotor of the motor 2. The motor 2 has a configuration that does not require a Hall element.

  The above is the configuration of the electronic devices 300a and 300b. By employing the motor drive circuit 100 according to the embodiment in the vibration device 302, it is possible to prevent the rotor from rotating backward due to the reverse rotation brake and to keep the vibration, and to immediately stop the vibration.

  Although the present invention has been described using specific terms based on the embodiments, the embodiments only illustrate the principles and applications of the present invention, and the embodiments are defined in the claims. Many variations and modifications of the arrangement are permitted without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 2 ... Motor, 4 ... Hall element, 100 ... Motor drive circuit, 102 ... Hall comparator, 110 ... Control part, 130 ... Drive part, S1 ... Control command, S2 ... Rectangular signal, S3 ... Drive signal, S4 ... Count value, S5: Period data, S6: Section length data, S7: End signal, 112 ... Energization control unit, 114 ... Reverse brake control unit, 116 ... Edge counter, 118 ... Period measurement unit, 120 ... Determination unit, 120a ... First determination , 120b ... second determination unit, 122 ... timer circuit, 150 ... memory, 152 ... comparator, 154 ... adder, 156 ... register, 160 ... timer circuit, 162 ... register, 164 ... logic gate, 170 ... edge counter 172, a comparator, 174, a register, 300, an electronic device, 302, a vibration device, 304, a host processor.

Claims (33)

A control unit that generates a drive signal for controlling energization of the coil of the motor based on a rectangular signal indicating the position of the rotor of the motor to be driven;
A drive unit for driving the coil based on the drive signal;
With
The control unit monitors a cycle of the rectangular signal during a reverse brake period, and terminates the reverse brake when the cycle becomes shorter.   2. The motor drive circuit according to claim 1, wherein the control unit ends the reverse brake based on a magnitude relationship between a current cycle and a past cycle. When the current period is T _CUR , the past period is T _PRE , and a correction value of 0 or more is T _CORR ,
T _CUR + T _CORR ≦ T _PRE
The motor drive circuit according to claim 2, wherein the reverse brake is terminated when the condition is satisfied. When the current period is T _CUR and the past period is T _PRE ,
T _CUR <T _PRE
The motor drive circuit according to claim 2, wherein the reverse brake is terminated when the condition is satisfied.   The motor driving circuit according to claim 2, wherein the past cycle is a cycle measured once before.   5. The motor drive circuit according to claim 2, wherein the past cycle is based on a plurality of cycles measured over the most recent predetermined number of times.   The motor drive circuit according to claim 1, further comprising a hall comparator that compares a pair of hall signals having opposite phases from the hall element and generates the rectangular signal.   8. The motor drive circuit according to claim 1, wherein the controller ends the reverse brake when the period of the rectangular signal becomes longer than a predetermined threshold during the reverse brake period. 9. .   The control unit includes an edge counter that measures the number of edges of the rectangular signal during a reverse brake period, and ends the reverse brake when a count value of the edge counter exceeds a predetermined threshold value. A motor drive circuit according to any one of claims 1 to 7.   8. The control unit according to claim 1, wherein the control unit includes a timer circuit that measures the length of the reverse brake period, and ends the reverse brake when the reverse brake period reaches a predetermined time. The motor drive circuit described.   11. The motor drive circuit according to claim 1, wherein the motor drive circuit is integrated on a single semiconductor substrate. A vibration motor having an eccentric weight attached to the rotor;
The motor drive circuit according to any one of claims 1 to 11, wherein the vibration motor is rotated;
A vibration device comprising:   An electronic apparatus comprising the vibration device according to claim 12. A motor driving method,
Comparing a pair of Hall signals of opposite phase from the Hall element to generate a rectangular signal;
Energizing the coil of the motor in synchronization with the rectangular signal;
When the stop of the motor is instructed, applying a reverse brake;
Monitoring the period of the rectangular signal during the reverse brake period, and ending the reverse brake when the period becomes shorter;
A driving method comprising: A control unit that generates a drive signal for controlling energization of the coil of the motor based on a rectangular signal indicating the position of the rotor of the motor to be driven;
A drive unit for driving the coil based on the drive signal;
With
When the control unit receives an instruction to stop the motor in a normal driving state of the motor, the control unit applies a reverse brake with an output corresponding to the normal driving state until then.   The motor drive circuit according to claim 15, wherein the control unit changes the output of the reverse brake according to the number of times of switching of the rectangular signal generated in the normal drive state.   The control unit includes an edge counter that measures the number of edges of the rectangular signal in the normal driving state, and changes the output of the reverse brake according to a count value of the edge counter. Item 17. The motor drive circuit according to Item 16.   When the controller receives an instruction to stop the motor, when the number of edges of the rectangular signal measured so far is smaller than a predetermined threshold, the controller outputs the reverse brake output compared to when it is larger. The motor drive circuit according to claim 17, wherein the motor drive circuit is lowered.   The control unit, when receiving an instruction to stop the motor, does not apply a reverse brake when the number of edges of the rectangular signal measured so far is smaller than a predetermined threshold value. Item 18. A motor drive circuit according to Item 17.   The motor drive circuit according to claim 15, wherein the control unit changes an output of the reverse brake according to a length of the normal drive state.   The motor according to claim 16, wherein the control unit includes a timer circuit that measures a length of the normal driving state, and changes an output of the reverse brake according to a measurement time of the timer circuit. Driving circuit.   The control unit, when receiving an instruction to stop the motor, reduces the output of the reverse brake when the measurement time is shorter than a predetermined threshold as compared with when the measurement time is long. The motor drive circuit described in 1.   The motor drive circuit according to claim 21, wherein the control unit does not apply the reverse brake when the measurement time is shorter than a predetermined threshold when receiving an instruction to stop the motor.   The motor drive circuit according to any one of claims 15 to 23, further comprising a hall comparator that compares a pair of hall signals having opposite phases from the hall element and generates the rectangular signal.   The motor drive circuit according to any one of claims 15 to 24, wherein the control unit ends the reverse brake when a period of the rectangular signal becomes longer than a predetermined threshold during the reverse brake period. .   The control unit includes an edge counter that measures the number of edges of the rectangular signal during a reverse brake period, and ends the reverse brake when a count value of the edge counter exceeds a predetermined threshold value. The motor drive circuit according to any one of claims 15 to 25.   27. The control unit according to claim 15, further comprising a timer circuit that measures the length of the reverse brake period, and ends the reverse brake when the reverse brake period reaches a predetermined time. The motor drive circuit described.   28. The motor drive circuit according to claim 15, wherein the motor drive circuit is integrated on a single semiconductor substrate. A vibration motor having an eccentric weight attached to the rotor;
The motor drive circuit according to any one of claims 15 to 28, wherein the vibration motor is rotated;
A vibration device comprising:   An electronic apparatus comprising the vibration device according to claim 29. A motor driving method,
Comparing a pair of Hall signals of opposite phase from the Hall element to generate a rectangular signal;
Energizing the coil of the motor in synchronization with the rectangular signal;
When an instruction to stop the motor is generated in the normal driving state of the motor, applying a reverse brake with an output according to the normal driving state until then;
A driving method comprising:   32. The driving method according to claim 31, wherein the step of applying the reverse brake changes the output of the reverse brake according to the number of times the rectangular signal is switched in the normal driving state.   32. The drive method according to claim 31, wherein the step of applying the reverse brake changes the output of the reverse brake according to the length of the normal drive state.

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