JPH07177932A - Motor-driven toothbrush - Google Patents

Abstract

PURPOSE:To provide the motor-driven toothbrush, which can use a battery power source at a low voltage, with respect to the motor-driven toothbrush for controlling the rotating speed of a motor. CONSTITUTION:Among respective switches SW1-SW4 consisting of a forward/ backward rotation switching circuit 1, the switches positioned at counter sides are provided with interlocking functions for simultaneously performing the same operation. A control element Q1 is controlled by a control circuit 2, and the control circuit 2 turns on/off a driver transistor Q2 inserted into the base circuit of the control element Q1. When the driver transistor Q2 is turned on, the control element Q1 is turned on through forward biasing of the base with the bias circuit of resistors R1 and R2 and with this ON operation, a motor M is connected through the forward/backward operation switching circuit 1 to a battery power source VB and operated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric toothbrush.

[0002]

2. Description of the Related Art An electric toothbrush is provided in which a motor is driven by using a battery as a power source, the rotation of the motor is reduced by a speed reducer, and the rotary motion is converted into the motion of a toothbrush through a motion conversion mechanism. There is no one that uses a mechanical switch as a switch to control the rotation speed of a motor.

There is also provided an electric toothbrush for switching the rotation direction of a motor using a bridge circuit composed of semiconductor switch elements.

[0004]

As described above, when the direction of rotation of the motor is switched by the bridge circuit composed of semiconductor switch elements, when the power source is a battery, the power source voltage is low, so that the semiconductor of the bridge circuit is changed. The voltage drop in the switch element cannot be ignored, and as a result, it is necessary to reduce the motor voltage specifications to allow current to flow in order to achieve the same torque, but the drive current becomes large, so the voltage drop in the semiconductor switch element There was a problem that it became even more vicious.

The present invention has been made in view of the above problems, and an object thereof is to provide an electric toothbrush capable of using a low-voltage battery power source in an electric toothbrush for controlling the rotation speed of a motor. It is in.

[0006]

According to a first aspect of the present invention, in an electric toothbrush having a battery power source, a motor, a speed reducer, and a motion converting mechanism, between output terminals of a bridge circuit composed of four mechanical switches. A motor and a control element for controlling the rotation speed of the battery-powered motor as well as switching the rotation direction of the motor by switching the energization direction to the motor by turning on / off switches located on opposite sides of the bridge circuit. Is turned on / off by a contact signal of a switch of the bridge circuit.

According to the second aspect of the present invention, the forward / reverse rotation direction of the motor is determined by determining the contact signal of the switch. In the invention of claim 3, a preset load curve is set in accordance with the forward and reverse directions of the rotation direction of the motor, and the load curve and the motor current are compared to control the rotation speed of the motor. A control circuit is provided.

According to another aspect of the invention, there is provided a PWM control circuit for driving the control element with a PWM signal, and the control circuit supplies power to the PWM control circuit when the load detected from the motor current exceeds a certain value. Alternatively, it controls the rotation speed setting unit that adjusts the reference voltage applied to the PWM control circuit to change the duty of the PWM signal, or controls the generated duty or the generated frequency of the PWM signal output from the PWM control circuit.

According to a fifth aspect of the invention, the control circuit for controlling the generated duty or the generated frequency stepwise is provided. In the invention of claim 6, after the motor is stopped, the generated duty or the generated frequency is increased stepwise so that the rotation speed of the motor is increased stepwise and returned to the predetermined rotation speed when the load on the motor disappears. The above-mentioned control circuit for controlling is provided.

According to a seventh aspect of the invention, the electric toothbrush according to the fourth aspect is provided with a control circuit for intermittently repeating the stop and operation of the motor. In the eighth aspect of the invention, the control circuit makes the repetition cycle variable. In the invention of claim 9, the control circuit automatically changes the repetition cycle.

In the tenth aspect of the present invention, during the stepwise change of the generated duty or the generated frequency, the motor current is sampled and it is detected that the load applied to the motor is less than the set value by the current value. The control circuit for controlling to return to a predetermined rotation speed at times is provided. According to the eleventh aspect of the present invention, a certain period is set after the motor is started to prohibit the detection of the motor current.

According to a twelfth aspect of the present invention, the control circuit comprises:
When the switch is turned on, the drive of the control element is delayed until the operation of the PWM control circuit becomes stable.
It has a function of controlling the M control circuit. According to a thirteenth aspect of the present invention, a certain period of time during which the detection of the motor current is prohibited after the motor is restarted is set, and the presence or absence of a load is detected by controlling the motor to rotate at a low speed after the certain period. Is.

According to a fourteenth aspect of the present invention, there is provided a PWM control circuit for driving the control element with a PWM signal, and means for detecting a counter electromotive voltage of the motor by a resistance bridge. An error amplifier for taking in the electromotive voltage is provided, and means for comparing the output of the error amplifier with the triangular wave generated by the triangular wave generating circuit to output a PWM signal whose duty is controlled so that the counter electromotive voltage becomes constant. It is a thing.

According to a fifteenth aspect of the present invention, a pulse voltage is applied to the motor through the control element and the PW is applied.
The back electromotive force is input to the error amplifier of the M control circuit through a filter. In the sixteenth aspect of the present invention, a rechargeable battery is used as the battery power source, and the control element is held in the off state when there is a signal for detecting that the rechargeable battery is being charged.

According to a seventeenth aspect of the present invention, the charger and the electric toothbrush body are separated from each other, and a secondary coil that is electromagnetically coupled to the primary coil provided on the charger side in a non-contact manner is provided in the electric toothbrush body. The charging is detected by the voltage induced in the secondary coil. In the invention of claim 18, the secondary coil also serves as a charging coil for charging the rechargeable battery.

[0016]

According to the first aspect of the present invention, a switch that doubles as a motor forward / reverse switching and a power switch is mechanically constructed, and the contact signal of the switch is used for controlling the energization of the control element. Since a switching driver circuit is not required and the voltage drop at the switch can be almost ignored, it is not necessary to consider the voltage drop even when using a low-voltage battery power supply. Therefore, make the motor voltage specifications compatible with the power supply voltage used. Therefore, the current consumption of the motor can be reduced and the circuit loss can be reduced. As a result, the cost and the size can be reduced.

According to the second aspect of the present invention, since the forward and reverse of the rotation direction of the motor is determined by determining the contact signal of the switch, it is not necessary to perform complicated signal processing, and the switch is not required. Since it can be determined at the same time as the input of, the quick processing can be performed when the control utilizing the forward and reverse rotation is performed. In the invention of claim 3, a preset load curve is set in accordance with the forward and reverse directions of the rotation direction of the motor, and the load curve and the motor current are compared to control the rotation speed of the motor. Since the control circuit is provided, it is possible to control the rotation speed of the motor corresponding to the rotation direction of the motor.

According to another aspect of the invention, there is provided a PWM control circuit for driving the control element with a PWM signal, and the control circuit supplies power to the PWM control circuit when the load detected from the motor current exceeds a certain value. Alternatively, it controls the rotation speed setting unit that changes the duty of the PWM signal by adjusting the reference voltage applied to the PWM control circuit or controls the generated duty or the generated frequency of the PWM signal output from the PWM control circuit. When the motor is stopped when the load increases due to an increase in pressure or the like, the toothbrush user can perform a smooth stop with little discomfort.

According to the fifth aspect of the present invention, since the control circuit for controlling the generated duty or the generated frequency stepwise is provided, the motor of the toothbrush can be stopped more smoothly without making the user feel uncomfortable. Can be made. In the invention of claim 6, after the motor is stopped, the generated duty or the generated frequency is controlled stepwise so that the rotation speed of the motor is increased stepwise and returned to the predetermined rotation speed when the load on the motor is lost. Since the above control circuit is provided, the motor can be smoothly restarted without surprise to the user of the toothbrush.

According to the seventh aspect of the invention, since the control circuit for intermittently repeating the stop and operation of the motor is provided, a massage effect can be provided when brushing teeth. According to the eighth aspect of the invention, since the control circuit makes the repetition cycle variable, the massage effect can be adjusted to the user. In the invention of claim 9, since the control circuit automatically changes the repetition cycle, it is possible to automatically enhance the massage effect.

In the tenth aspect of the present invention, during the stepwise change of the generated duty or the generated frequency, the motor current is sampled and it is detected that the load applied to the motor is equal to or less than the set value by the current value. Since a control circuit for controlling to return to the predetermined rotation speed at times is provided, the rotation speed of the motor is quickly returned to the predetermined rotation speed in the middle of the stop operation, or the motor is quickly activated when the load increases in the return process. Can be stopped and does not irritate the user.

According to the eleventh aspect of the present invention, since a fixed period of time during which the detection of the motor current is prohibited from when the motor is started is set, even if a large motor current flows at the time of starting the motor, it can be regarded as an increase in load. Therefore, it is possible to prevent an accidental stop of the motor at the time of starting. In the invention of claim 12, the control circuit has a function of controlling the PWM control circuit so as to delay the drive of the control element until the operation of the PWM control circuit is stabilized when the switch is turned on. It is possible to eliminate erroneous control when the operation is unstable at the time of turning on.

According to the thirteenth aspect of the present invention, the presence or absence of a load is detected by setting a fixed period during which the detection of the motor current is prohibited after the motor is restarted and controlling the motor to rotate at a low speed after the fixed period. Since it does so, it can be restarted without surprising the toothbrush user. Claim 1
In the invention of 4, the PW for driving the control element by the PWM signal
The PWM control circuit includes an M control circuit and means for detecting the back electromotive force of the motor by a resistance bridge, and the PWM control circuit includes an error amplifier that takes in the back electromotive force of the motor, and the output of the error amplifier and the triangular wave generated from the triangular wave generation circuit. Since a means for outputting a PWM signal whose duty is controlled so that the detected back electromotive force is constant by comparing with, is provided, the characteristics of the electronic governor method and the characteristics of the PWM control method can be utilized, The circuit configuration can be downsized and the circuit loss can be reduced.

According to the fifteenth aspect of the present invention, the pulse voltage is applied to the motor through the control element, and the counter electromotive voltage is input to the error amplifier of the PWM control circuit through the filter. The filter can be downsized and the cost can be reduced. In the invention of claim 16,
A rechargeable battery is used as the battery power source, and the control element is held in the off state when there is a signal to detect that the rechargeable battery is being charged. Therefore, in the rechargeable electric toothbrush, it is possible to prevent charging mistakes due to forgetting to turn off the switch. .

According to a seventeenth aspect of the present invention, the charger and the electric toothbrush main body are separated from each other, and a secondary coil that is electromagnetically coupled to the primary coil provided on the charger side in a non-contact manner is provided in the electric toothbrush main body. Since the charging is detected by the voltage induced in the secondary coil, the waterproof electric toothbrush main body can be easily realized, and the charging can be started only in the vicinity of the charger and the electric toothbrush main body. Further, since the electric signal generated at the time of charging is used as a signal for maintaining the OFF state of the control element, it is possible to automatically stop the energization of the motor at the same time as the start of charging.

In the eighteenth aspect of the present invention, since the secondary coil also serves as the charging coil for charging the rechargeable battery, the charging power and the signal extraction for turning off the control element are the same. Since the coil can be used in common, the cost can be reduced and the size can be reduced.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 shows a circuit configuration of this embodiment.
In this embodiment, the motor between the four mechanical switches SW ₁ to SW ₄ constitutes a normal and reverse rotation switching circuit 1 of the motor M being a DC motor by a bridge connecting the bridge circuit, the input terminal of the normal and reverse rotation switching circuit 1 A battery power source V _B is connected through a control element Q ₁ for controlling the rotation speed of M.

Each switch S constituting the forward / reverse switching circuit 1
The switches located on opposite sides of W _{1 to} SW ₄ have the interlocking function to perform the same operation at the same time, and the connection point of the switches SW ₁ and SW ₃ connected in series and the switch SW.
₄ , the current flowing in the motor M connected between the connection point of SW ₄ and SW ₄ is switched SW ₁ → a terminal of the motor M → b terminal of the motor M → current I ₁ flowing through the switch SW ₄ and switch SW ₂ → b terminal of the motor M → a terminal of the motor M → switch the switch SW ₃ and the flowing current I ₂ to the motor M
Can be rotated forward / backward.

Control element Q₁Is controlled by the control circuit 2
The control circuit 2 includes a control element Q₁The ba
Driver transistor Q inserted in the circuit₂The
Turn off. Control element Q₁Is the driver transistor Q
₂When turned on, the resistance R₁, R ₂Bias circuit
The base is forward-biased and turned on.
From the forward / reverse rotation switching circuit 1, the motor M is powered by a battery.
V_BTo operate the motor M.

The control circuit 2 is intended to receive a power supply from the battery power source V _B via the transistor Q _3, transistor Q ₃ are the resistances R _3, R ₄ and base respectively through in the forward and reverse switching circuit 1 switches Connected to the connection point of SW ₁ and SW _{2 and} the connection point of switches SW ₃ and SW _{4, respectively} , and when the switch SW ₃ or SW ₄ is turned on, the base current flows through the switch SW ₃ or SW ₄ and turned on. , The switches SW ₃ and SW ₄ are off, the base current is cut off and turned off.

That is, the switch S of the forward / reverse switching circuit 1
The transistor Q ₃ is turned on / off according to the contact signals of W ₃ and SW ₄ to control the energization of the control circuit 2, and as a result, the energization of the control element Q ₁ is controlled by the forward / reverse switching circuit 1. ON / OFF according to the contact signals of switches SW ₃ and SW _4.
It will be cut. Then, when the switches SW ₁ , SW ₄ or SW ₂ , SW ₃ of the forward / reverse switching circuit 1 are turned on,
The transistor Q ₃ turns on and the control circuit 2 receives the battery power V
Power is supplied from _B. The control circuit 2 generates an output in response to the power supply and turns on the driver transistor Q ₂ . When the driver transistor Q ₂ is turned on, the control element Q ₁ is driven by the base current flowing. Therefore, the motor M, to which the battery power source V _B is connected to the forward / reverse switching circuit ₁ through the control element Q ₁ , rotates.

The switch SW in the ON state of the forward / reverse switching circuit 1.
_{When 1} , SW ₄ or SW ₂ , SW ₃ is turned off, the transistor Q ₃ is turned off and the power supply of the control circuit 2 is stopped,
As a result, the drive of the control element Q ₁ is stopped, and the motor M stops rotating. Here, the switches SW _{1 to} S of the forward / reverse switching circuit ₁
Since W ₄ is composed of a mechanical switch, its voltage drop can be almost ignored, and the voltage drop between the battery power source V _B and the motor M is only the voltage drop V _ce between the emitter and collector of the control element Q _1. Become. That is, when the switch of the bridge circuit is composed of, for example, a transistor, the control element Q ₁
For emitter-collector voltage drop between the emitter and collector of the two transistors to the voltage drop V _ce of V _ce content but is added, which in the case of this embodiment this amount is not applied, the voltage of the battery power source V _B Can be lowered. Further, since the control circuit 2 does not need to drive the transistor that constitutes the switch of the bridge circuit, the circuit configuration can be simplified.

As described above, in the present embodiment, since the forward / reverse switching is achieved by the mechanical switch and the rotation speed of the motor M is electronically controlled, a low voltage battery power source can be used and the motor consumption can be reduced. Current can be reduced and efficiency improved,
It is possible to reduce costs and downsize. (Embodiment 2) FIG. 2 shows the circuit of this embodiment. In this embodiment, the rotation direction of the motor M is fed back to the rotation control of the motor M, and the control circuit 2 is normally rotated. It has a signal input end FF and a reverse rotation signal input end REW. The forward rotation signal input end FF is connected to the b terminal of the motor M via the resistor R ₆ , and the reverse rotation signal input end REW is connected to the motor via the resistor R _7. It is connected to the a terminal of M, and the switch SW ₁ ,
When SW ₄ is turned on and the current for rotating the motor M in the forward direction is flowing, the voltage at the terminal a becomes “H” and a forward signal is given, and the switches SW ₂ and SW ₃ are turned on. When a current for rotating the motor M in the reverse rotation direction is flowing, the voltage at the terminal b becomes "H" and a reverse rotation signal is given.

The control circuit 2 controls the speed of the motor M by changing the control condition of the control element Q ₁ depending on whether the forward rotation signal is input or the reverse rotation signal is input. . (Embodiment 3) In addition to the circuit of Embodiment 2, this embodiment is similar to FIG.
The motor current flowing in the motor M is converted into a voltage by the resistor R ₅ , and this voltage value is amplified by the amplifier 3 as shown in
A circuit for inputting to the A / D conversion terminal of the control circuit 2 is provided, and the control circuit 2 has load curves FF and R showing the relational characteristics of the torque and motor current corresponding to the forward rotation signal and the reverse rotation signal, respectively.
The function of presetting EW (shown in FIG. 4) and the above A /
The current detection function of converting the voltage input to the D conversion terminal into a digital value to detect the motor current value, the load curve selected by the input signal, and the detected current value are compared to correspond to the predetermined torque T1. A comparison function is provided to turn off the driver transistor Q ₂ when a current value is detected.

Thus, in this embodiment, the control circuit 2 selects the load curve FFFF or REW according to the rotation direction of the motor M, compares the relationship characteristic with the detected current value, and responds to the constant torque T1. When the current value I ₀ is detected, that is, when the brushing pressure reaches a constant value, the driver transistor Q
₂ is turned off to stop the driving of the control element Q ₁ , and the motor M
To stop the rotation of.

(Embodiment 4) In this embodiment, the control element Q _{1 is set} to P
The WM control is performed to control the rotation speed of the motor M. As shown in FIG. 5, the control element Q ₁ is a PWM control circuit 4
On / off drive is performed by the PWM signal of. The PWM control circuit 4 includes a stabilizing circuit 40, a triangular wave generating circuit 41, a comparator 42, and an output transistor Q _4, and the stabilizing circuit 40 supplies power to the battery power source V _B via the transistor Q _3. It receives and generates a constant voltage. This constant voltage is divided by the variable resistor VR that adjusts the rotation speed of the motor and becomes the reference voltage Vref of the comparator 42. The comparator 42 compares the triangular wave output from the triangular wave generation circuit 41 with the reference voltage Vref shown in FIG. 6 (a), and as shown in FIG. 6 (b), the reference voltage Vref does not exceed the level of the triangular wave. The output of "L" is generated in the period exceeding the output of "H", and the output transistor Q ₄ is turned on / off by this output. The operation of the comparator 42 is the DT of the control circuit 2.
This is performed when the output DT of the terminal is "L" and stopped when it is "H".

The control circuit 2 switches the forward and reverse points similarly to the second embodiment.
Circuit 1 and battery power V_BResistance R inserted between_Fiveof
The output of the amplifier 3 that amplifies the voltage between both ends is taken from the A / D terminal.
Detects the motor current value by importing and performing A / D conversion
Function and the FF end that is normally lifted to "H" level
Child, REW terminal is switch SW of forward / reverse switching circuit 1₃or
Is SW_FourIs turned to "L" level by turning on the
The rotation direction is detected at the same time when the power-on operation is detected.
When the power-on operation is detected, the transistor Q ₃Turn on
The function to set the ST terminal to "L" for driving, and
Select the load curve FF or REW and select the selected load
The FF or REW and the detected motor current value
Motor current I corresponding to constant torque T1₀Is detected
Equipped with a function to switch the output DT from "L" to "H"
ing.

When the battery power source V _B is connected and the switches SW ₁ , SW ₄ and SW ₂ , SW _{3 of the} forward / reverse switching circuit 1 are not turned on, the FF terminal of the control circuit 2 is turned on. , And REW terminals are both "H", the control circuit 2 sets the ST terminal to "H" and outputs the DT terminal DT.
Is "L". That is, since the transistor Q ₃ is off, power is not supplied to the PWM control circuit 4 and the control element Q ₁ is not driven.

Next, the switches SW _{1 of} the forward / reverse switching circuit ₁
When SW ₄ or SW _2, SW ₃ is turned on, FF terminal or REW terminal is connected to ground through the switch SW ₄ or SW _3, the therefore "L". When either the FF terminal or the REW terminal becomes "L", the control circuit 2 determines that the power-on operation is performed, sets the ST terminal to "L", and the terminal that becomes "L" causes the rotation direction of the motor M to change. Is detected and the relational characteristic FF or REW between the torque and the motor current according to the rotation direction is selected and set.

When the ST terminal of the control circuit 2 becomes "L",
The base current flows through the transistor Q ₃ and the transistor Q _3
3 turns on. By this turning on, the battery power supply V _B is connected to the stabilizing circuit 40 of the amplifier 3 and the PWM control circuit 4 through the transistor Q ₃ , and the amplifier 3 and the PWM control circuit 4 start operating. Here, when the power is turned on, before brushing the teeth, the motor M is not heavily loaded. Therefore, the detected motor current value is the current I ₀ corresponding to the predetermined torque T1 of the selectively set relational characteristic. Since it is smaller, the control circuit 2 holds the output DT at "L". Therefore, the comparator 42 of the PWM control circuit 4 compares the reference voltage Vref with the level of the triangular wave from the triangular wave generation circuit 41, and generates the PWM signal shown in FIG. 6B. The PWM signal turns on / off the transistor Q ₄ to drive the control element Q ₁ . This control element Q
_The pulse voltage PWM-controlled by the drive of ₁ is applied to the motor M through the switches SW ₁ , SW ₄ or SW ₂ , SW ₃ of the forward / reverse switching circuit 1 to control the rotation speed of the motor M.

When the brushing pressure increases and the motor current corresponding to the predetermined torque is detected, the control circuit 2 inverts the output DT from "L" to "H" as shown in FIG. 6 (a),
The output of the comparator 42 of the PWM control circuit 4 is stopped.
If the output DT is oscillated at a frequency lower than the carrier frequency of the PWM control circuit 2 when the torque control is applied so that the rotation of the motor M is gradually slowed to the stop, the user of the toothbrush feels uncomfortable. There will be a smooth feeling of stoppage. In addition to the above method, such control can be performed by controlling the output of the ST terminal of the control circuit 2 that controls the power supply of the PWM control circuit 4 or by changing the reference voltage Vref that is the rotation speed setting unit. It is also possible to change the detail in addition to the cycle of the generation frequency of the output DT.

(Embodiment 5) In this embodiment, when the output DT of the control circuit 2 is oscillated as shown in FIG. 7, the cycle and duty thereof are switched stepwise to slow the rotation speed of the motor M stepwise. In this way, a smooth stop feeling is provided and after the motor M is stopped, the output DT is oscillated so that the rotation speed is increased stepwise when the load is removed and the motor M is rotated again. It was designed to give you a smooth start.

(Embodiment 6) In this embodiment, when the output DT of the control circuit 2 is oscillated as described above, FIG.
As shown in (b), the period is delayed or the width of the duty is changed to make it intermittent so that a massage effect on the gum can be provided. It is also possible to further enhance the massage effect by automatically adopting 1 / f fluctuation, fuzzy control or the like when changing the cycle or duty.

(Embodiment 7) In the above-mentioned Embodiment 4, the motor current I ₀ corresponding to the constant torque T1 is increased by increasing the tooth brushing pressure and the like.
9 is detected, the rotation speed of the motor M is gradually reduced and stopped. However, in the present embodiment, when the rotation speed of the motor M becomes lower than a certain torque T1 while the rotation speed of the motor M is being reduced, as shown in FIG. As shown in, the control circuit 2 increases the rotation speed of the motor M stepwise and returns it to the set rotation speed.
Controls the output DT in accordance with the detected motor current value.
Even when the rotation speed of the motor M is increased stepwise at the time of restarting after the stop, when the motor current value I ₀ corresponding to the constant torque T1 is detected, the rotation speed of the motor M is changed stepwise from that point. The output DT may be controlled so as to be lowered.

By doing so, the rotational speed of the motor M can be quickly returned to the set rotational speed or stopped, and an effect that does not annoy the user can be obtained. In the control circuit 2 as in the third to sixth embodiments, when the current value of the motor M reaches the preset current value I ₀ , the control is performed so as to stop the rotation of the motor M. , When the switches SW ₁ , SW ₄ or SW ₂ , SW ₃ of the forward / reverse switching circuit 1 are turned on, the starting current value flowing in the motor M exceeds the current value I _0, and the control for stopping the motor M is performed. Therefore, the operation program of the control circuit 2 may be set so as to set a period in which the operation of A / D converting the NO output of the amplifier 3 and sampling the motor current value is prohibited at the time of startup. Further, instead of setting the prohibition period, it may be restricted by the magnitude of the starting current.

(Embodiment 8) Since the electric toothbrush can be used in different toothbrushes, the shape and mechanism of the toothbrush may change, and the torque without load may change. In this embodiment, the torque under no load is added when setting the constant torque T1 (motor current value I ₀ ) which is the threshold value for stopping the motor M. The specific circuit is shown in FIG. As shown in FIG. 10, it is basically the same as the circuit of the fourth embodiment, and the control circuit 2 has the above-mentioned function.

By the way, when using an electric toothbrush, most people use switches SW ₁ , SW ₄ or SW ₂ , SW ₃
Immediately after the operation, start brushing. Therefore, as described above, the period in which the motor current without load corresponding to the torque without load can be detected is only a short time immediately after the start of the motor M. Further, if the operation of the control circuit 2 is not stable when the motor M is started, even if the period for prohibiting the sampling of the motor current is provided as described above, if the transient phenomenon continues for a long time and bounting or the like occurs, the original no load occurs. A value lower than the current is detected, which may adversely affect the control.

Therefore, in the present embodiment, the switches SW ₁ , S
When there is an operation of W ₄ or SW ₂ , SW ₃ , first the control circuit 2
The output of the ST terminal is changed from "H" to "L" as in the fourth embodiment.
To supply power to the PWM control circuit 4 and the amplifier 3,
After that, the output DT is switched from "H" to "L" and PW
A PWM signal is generated from the comparator 42 of the M control circuit 4. That is, since the operation of the reference voltage Vref and the triangular wave generating circuit 41 is stabilized, the control element Q ₁ is driven to operate the motor M, and the transient phenomenon time at the time of startup is minimized. The information on the power supply voltage of the PWM control circuit 4 and the reference voltage Vref may be fed back through another A / D terminal of the control circuit 2 to determine whether the operation of the PWM control circuit 4 is stable. The inversion timing of the output DT may be set based on the time measured in advance.

In this embodiment, as described above, the torque under no load is detected by detecting the motor current under no load.
Since the constant torque T1 that is the threshold value for torque control is taken into consideration, the motor M that is appropriate even if the toothbrush changes
The rotation speed of can be controlled. (Embodiment 9) In each of the above embodiments, when the toothbrushing pressure reaches a certain value or more, the rotation of the motor M is stopped, the motor M is restarted after the stop, and the toothbrushing pressure at that time is smaller than the certain value. It is sufficient to keep the rotation of the motor M at the set speed, but if the motor M is suddenly rotated at the time of restarting, a load is applied in the mouth, which may cause a user to be surprised. Therefore, in the present embodiment, as shown in FIG. 11, the FB terminal of the PWM control circuit 4 to which the reference voltage Vref for setting the rotation speed is connected is connected to the SL terminal of the control circuit 2 via the resistor R ₈ , and the control circuit 2 is connected. When the motor M is restarted, the SL terminal is set to "L" to lower the reference voltage Vref given to the PWM control circuit 4, that is, the reference voltage Vref is lowered so as to lower the rotation speed of the motor M, and a sudden rotation is performed. We try to avoid surprises to the user due to increased speed. Further, by doing so, it is possible to eliminate the discomfort caused by the repeated stop and start of the motor M, which is a drawback of the control of the electric toothbrush.

(Embodiment 10) Conventionally, an electronic governor system is often used to control the rotation speed of a small motor to a constant value, but this system is very effective in simplifying the circuit, and is similar to an electric toothbrush. Although it is convenient to mount it in a narrow shape, since the control element is operated in series, there is a problem that heat generation is large. Therefore, such an electronic governor system could not be adopted for an electric toothbrush with a large motor current.

In this example, the PW used in Examples 4 to 9 was used.
M control system and this electronic governor system are used together
The rotation speed of the is controlled to be constant, and further downsizing and loss reduction are achieved. FIG. 12 shows the circuit of this embodiment. In this embodiment, the counter electromotive voltage generated in the motor M is taken out, and the motor current is controlled so that the counter electromotive voltage becomes constant. Is kept constant.

That is, when the motor current is IM when the motor M is rotating, EM = Ra.IM at both ends of the motor M.
A voltage of + EG is generated. The voltage EG included in this voltage EM is the above-mentioned counter electromotive voltage, and the counter electromotive voltage EG is the resistance R ₅ , the internal resistance Ra of the motor M, and the resistances R ₁₀ and R _11.
It is designed to be extracted by the resistance bridge circuit of and to be taken into the error amplifier 43 provided in the PWM control circuit 4. Here, the resistance ratios of the resistors R ₅ and R ₁₀ and the internal resistors Ra and R ₁₁ are set to be the same, and the error amplifier 4 of the PWM control circuit 4 is set.
The voltage input to 3 is normally kept in balance and the back electromotive force EG
The component is output to the error amplifier 43. The rotation speed of the motor M can be adjusted by changing the reference voltage Vref by adjusting the variable resistor VR to adjust the counter electromotive voltage EG.

In the PWM control circuit 4, the output of the error amplifier 43 is compared with the level of the triangular wave of the triangular wave generating circuit 41 to create a PWM signal, and the control element Q ₁ is driven in the same manner as in the fourth to ninth embodiments. It has become. At this time, the input voltage of the error amplifier 43 becomes a pulse, and in principle, the counter electromotive voltage EG can be taken out, but in the embodiment, the resistance R ₁₂ ,
A filter composed of a resistor R ₁₃ and a capacitor C _{2 is used} for phase adjustment of ± input voltages. Normal PWM
In the case of control, an LC filter is used after the control element, but in this embodiment, for downsizing and cost reduction,
The filter as described above is used because the influence of the noise of the electric toothbrush is small. It is a thing.

The rotation stop control of the motor M by the control circuit 2 is performed.
Power supply operation by turning on the power, and further forward / reverse rotation
The operation based on the detection of the direction is similar to those in the fourth to ninth embodiments.
Therefore, the description is omitted. (Embodiment 11) In each of the above embodiments, the battery power source V_BUsing
However, it is not enough for daily use like an electric toothbrush.
Many are electric. However, the battery capacity of the rechargeable battery is exhausted
If it does, it will not operate and the user
If you try to charge the rechargeable battery with the power switch turned on,
There is a match. In this case, the charging current flows to the motor and the charging battery
I can't charge the battery
Then, the rechargeable battery may not be charged at all.
There were many. Therefore, mechanical switches, reed switches, etc.
Has been used, but in the case of a mechanical switch, a toothbrush
From the unique structure of the
If you use a hard switch,
There was a problem. In this embodiment, the circuit of the control system of the motor M is
Adopts a circuit similar to that of the first embodiment, and uses the battery power source V_BAs
It uses a rechargeable battery, but the charger 5 side and electric teeth
Separated into the brush main body 6 and charged to the electric toothbrush main body 6 side.
Primary coil L provided on the electric appliance 5 side ₁Electromagnetically coupled with
Secondary coil L₂Is equipped with an electric tooth bra for the charger 5.
When the chargers are placed close to each other, the primary
IL L₁The magnetic flux generated in the secondary coil L₂Chained to 2
Next coil L₂Output to the rectifier
Rectify with REF and charge battery V_BGot to charge
There is. In addition, the secondary output is diode D₀With half-wave rectification
And capacitor C₀The voltage smoothed by is supplied to the control circuit 2.
Transistor Q for supplying power₃Connect to the base of
ing.

Therefore, in this embodiment, even if charging is performed with the switches SW ₁ , SW ₄ or SW ₂ , SW ₃ of the forward / reverse switching circuit 1 being turned on, the resistor R ₉ and the resistor R ₄ or R _{4 are used.
A} voltage obtained by dividing the voltage across the capacitor C _{1 by 3} and is applied to the base of the transistor Q ₃ so that the base voltage is 0.6V.
By maintaining the above, the reverse bias is applied and the off state is maintained.

That is, the resistance R₉And resistance R₃Or R_FourWith
Set the coercive ratio to reverse bias as above.
Switch SW even while charging the rechargeable battery 2.₁，
SW _FourOr SW₂, SW₃Is turned on even if
Register Q₃Power to the control circuit 2 by holding the power off state
Stop supply and control element Q₁To the motor M through the charging current
Is prevented from flowing. At this time, the resistance R₉And resistance R_Four
Or R₃The current flowing through the motor M through
Since it can be set with a value that has almost no effect when compared,
Ji SW₁, SW_FourOr SW₂, SW₃I forgot to cut
Even rechargeable battery V _BWill be able to charge.

Since the operation of the control circuit 2 is the same as that of the first embodiment, its explanation is omitted.

[0058]

According to the first aspect of the present invention, the switch that doubles as a motor forward / reverse switching and a power switch is mechanically configured, and the contact signal of the switch is used for controlling the energization of the control element. Since a switching driver circuit is unnecessary and the voltage drop at the switch can be almost ignored, it is not necessary to consider the voltage drop even when using a low-voltage battery power supply. Therefore, make the motor voltage specifications compatible with the power supply voltage used. Therefore, the current consumption of the motor can be reduced and the circuit loss can be reduced. As a result, the cost and the size can be reduced.

According to the second aspect of the present invention, since the forward and reverse of the rotation direction of the motor is determined by determining the contact signal of the switch, it is not necessary to perform complicated signal processing, and the switch is turned on. Since it is possible to make a determination at the same time, there is an effect that a quick process can be performed when performing control using forward and reverse rotation. According to a third aspect of the present invention, a preset load curve is set according to the forward and reverse directions of the rotation direction of the motor, and the rotation speed of the motor is controlled by comparing the load curve with the motor current. Since the control circuit is provided, it is possible to control the rotation speed of the motor corresponding to the rotation direction of the motor.

According to a fourth aspect of the invention, the drive of the control element is PWM.
A PWM control circuit for performing a signal is provided, and the control circuit adjusts the reference voltage applied to the power supply of the PWM control circuit or the PWM control circuit when the magnitude of the load detected from the motor current exceeds a certain value to adjust the duty of the PWM signal. Use of a toothbrush when the motor is stopped when the load increases due to an increase in toothbrushing pressure, etc., because it controls the generation duty or frequency of the PWM signal output from the PWM control circuit that controls the rotating speed setting unit to be changed. There is an effect that a smooth stop can be performed so that the person does not feel uncomfortable.

According to the invention of claim 5, the control circuit for controlling the generated duty or the generated frequency stepwise is provided. Therefore, the motor of the toothbrush can be stopped more smoothly without giving a feeling of strangeness to the user. The effect is that it can be done. According to a sixth aspect of the present invention, the generated duty or the generated frequency is controlled stepwise so that the motor rotation speed is increased stepwise and returned to a predetermined rotation speed when the load on the motor is lost after the motor is stopped. Since the above control circuit is provided, there is an effect that the motor can be restarted smoothly without surprise to the user of the toothbrush.

According to the seventh aspect of the invention, since the control circuit for intermittently repeating the stop and operation of the motor is provided, there is an effect that a massage effect can be provided when brushing teeth. The invention of claim 8 has an effect that the massage effect can be adjusted to the user because the control circuit makes the repetition cycle variable.

According to the ninth aspect of the invention, since the control circuit automatically changes the repetition cycle, there is an effect that the massage effect can be automatically enhanced. According to a tenth aspect of the present invention, during the stepwise change of the generated duty or the generated frequency, the motor current is sampled and a predetermined rotation is detected when it is detected that the load applied to the motor is equal to or less than a set value by the current value. Since a control circuit for controlling to return to the speed is provided, the rotation speed of the motor is quickly returned to a constant rotation speed during the stop operation, or the motor is stopped early when the load becomes large in the return process. Therefore, there is an effect that the user is not irritated.

According to the eleventh aspect of the present invention, the fixed period for prohibiting the detection of the motor current is set after the motor is started. Therefore, even if a large motor current flows at the start of the motor,
There is an effect that it is possible to prevent an erroneous motor stop at the time of startup without being regarded as an increase in load. Claim 1
According to a second aspect of the invention, the control circuit has a PW
Since the M control circuit has a function of controlling the PWM control circuit so as to delay the drive of the control element until the operation of the M control circuit becomes stable, it is possible to eliminate erroneous control at the time of unstable operation at power-on. There is.

According to a thirteenth aspect of the present invention, the presence or absence of a load is detected by setting a fixed period during which the detection of the motor current is prohibited after the motor is restarted, and controlling the motor to rotate at a low speed after the fixed period. Therefore, there is an effect that the restart can be performed without astonishing the user of the toothbrush. According to a fourteenth aspect of the present invention, a PWM control circuit for driving a control element for controlling the motor rotation speed by a PWM signal is provided, and a means for detecting a counter electromotive voltage of the motor by a resistance bridge is provided. An error amplifier which takes in the counter electromotive voltage and means for comparing the output of the error amplifier and the triangular wave generated from the triangular wave generation circuit and outputting a PWM signal whose duty is controlled so that the detected counter electromotive voltage becomes constant Therefore, the characteristics of the electronic governor method and the characteristics of the PWM control method can be used to the advantage that the circuit configuration can be downsized and the circuit loss can be reduced. There is an effect that the pulse voltage is applied to and the counter electromotive voltage is input to the error amplifier of the PWM control circuit through the filter.

According to the fifteenth aspect of the present invention, the pulse voltage is applied to the motor through the control element and the counter electromotive voltage is input to the error amplifier of the PWM control circuit through the filter. Miniaturization of
This has the effect of reducing costs. According to the sixteenth aspect of the present invention, the rechargeable battery is used as the battery power source, and the control element is held in the off state when there is a signal for detecting that the rechargeable battery is being charged. Therefore, in the rechargeable electric toothbrush, the switch is forgotten to be turned off. There is an effect that it is possible to prevent a charging error due to.

According to a seventeenth aspect of the present invention, the charger and the electric toothbrush main body are separated from each other, and a secondary coil which is electromagnetically coupled to the primary coil provided on the charger side in a non-contact manner is provided in the electric toothbrush main body. Since the charging is detected by the voltage induced in the secondary coil, the waterproof electric toothbrush main body can be easily realized, and the charging can be performed only by the close arrangement of the charger and the electric toothbrush main body. Further, since the electric signal generated at the time of charging is used as a signal for maintaining the OFF state of the control element, there is an effect that the power supply to the motor can be automatically stopped at the same time as the start of charging.

According to the eighteenth aspect of the invention, since the secondary coil also serves as a charging coil for charging the rechargeable battery, the charging power and the signal extraction for turning off the control element are the same. Since the coil can be used in common, there is an effect that the cost can be reduced and the size can be reduced.

[Brief description of drawings]

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

FIG. 2 is a circuit diagram of a second embodiment of the present invention.

FIG. 3 is a circuit diagram of Embodiment 3 of the present invention.

FIG. 4 is a torque-motor current relationship characteristic diagram used in the above.

FIG. 5 is a circuit diagram of a fourth embodiment of the present invention.

FIG. 6 is a timing chart for explaining the above operation.

FIG. 7 is an operation explanatory diagram of the fifth embodiment of the present invention.

FIG. 8 is a timing chart for explaining the operation of the sixth embodiment of the present invention.

FIG. 9 is an operation explanatory diagram of the seventh embodiment of the present invention.

FIG. 10 is a circuit diagram of Embodiment 8 of the present invention.

FIG. 11 is a circuit diagram of Embodiment 9 of the present invention.

FIG. 12 is a circuit diagram of Embodiment 10 of the present invention.

FIG. 13 is a circuit diagram of Embodiment 11 of the present invention.

[Explanation of symbols]

1 forward / reverse switching circuit 2 control circuit SW _{1 to} SW ₄ switch Q ₁ control element Q ₂ driver transistor Q ₃ transistor V _B battery power supply M motor

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[Procedure amendment]

[Submission date] May 16, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction content]

Thus, in this embodiment, the control circuit 2 selects the load curve FF or REW according to the rotation direction of the motor M, compares the relational characteristic with the detected current value, and responds to the constant torque T1. When the current value I ₀ is detected, that is, when the toothbrushing pressure reaches a certain value, the driver transistor Q ₂ is turned off to stop the driving of the control element Q ₁ and stop the rotation of the motor M.

Claims (18)

[Claims] 1. An electric toothbrush equipped with a battery power source, a motor, a speed reducer, and a motion conversion mechanism, wherein a motor is connected between output ends of a bridge circuit composed of four mechanical switches, and an opposite side of the bridge circuit is connected. By switching ON / OFF of the switches located at, the direction of energization to the motor is switched to switch the direction of rotation of the motor, and the energization of the control element for controlling the rotation speed of the battery-powered motor is switched to the contact signal of the switch of the bridge circuit. Electric toothbrush that is turned on / off by. 2. The electric toothbrush according to claim 1, wherein the forward / reverse direction of rotation of the motor is determined by determining a contact signal of the switch. 3. A control circuit for setting a preset load curve according to the forward and reverse directions of the rotation direction of the motor and comparing the load curve with the motor current to control the rotation speed of the motor. The electric toothbrush according to claim 2, further comprising: 4. A P for driving the control element with a PWM signal.
The WM control circuit is provided, and the control circuit adjusts the reference voltage applied to the power supply of the PWM control circuit or the PWM control circuit when the magnitude of the load detected from the motor current exceeds a certain value to change the duty of the PWM signal. 4. The electric toothbrush according to claim 3, wherein the number of setting parts is controlled or the generation duty or the generation frequency of the PWM signal output from the PWM control circuit is controlled. 5. The electric toothbrush according to claim 4, further comprising the control circuit for stepwise controlling the generated duty or the generated frequency. 6. The generated duty or the generated frequency is controlled stepwise so that after the motor is stopped, when the load applied to the motor disappears, the rotational speed of the motor is increased stepwise and returned to a predetermined rotational speed. The electric toothbrush according to claim 4, wherein the control circuit is provided. 7. A control circuit is provided for intermittently repeating the stop and operation of the motor.
Electric toothbrush as described. 8. The electric toothbrush according to claim 7, wherein the control circuit has a variable repeating period. 9. The electric toothbrush according to claim 8, wherein the control circuit automatically changes the repetition period. 10. The rotational speed of the motor when the motor current is sampled during the stepwise change of the generated duty or the generated frequency and it is detected from the current value that the load applied to the motor is below a set value. The electric toothbrush according to claim 4, wherein the control circuit is provided to control the motor to return to a predetermined rotation speed. 11. The electric toothbrush according to claim 3, wherein a fixed period of time during which the detection of the motor current is prohibited after the motor is started is set. 12. The control circuit has a function of controlling the PWM control circuit so as to delay the drive of the control element until the operation of the PWM control circuit becomes stable when the switch is turned on. The electric toothbrush according to claim 3. 13. A method for detecting the presence or absence of a load by setting a fixed period of time during which the detection of the motor current is prohibited after the motor is restarted, and controlling the motor to rotate at a low speed after the fixed period. The electric toothbrush according to claim 12. 14. A PWM control circuit for driving the control element with a PWM signal and means for detecting a back electromotive force voltage of a motor by a resistance bridge, wherein the PWM control circuit includes an error for taking in the back electromotive force voltage of the motor. An amplifier and means for comparing the output of the error amplifier with the triangular wave generated by the triangular wave generating circuit and outputting a PWM signal whose duty is controlled so that the counter electromotive voltage becomes constant are provided. The electric toothbrush according to claim 1. 15. The electric motor according to claim 14, wherein a pulse voltage is applied to the motor through the driving control element, and the back electromotive force is input to an error amplifier of the PWM control circuit through a filter. toothbrush. 16. The electric toothbrush according to claim 1, wherein a rechargeable battery is used as the battery power source, and the control element is held in an off state when there is a signal for detecting that the rechargeable battery is being charged. 17. A charger and an electric toothbrush body are separated from each other,
A secondary coil, which is electromagnetically coupled to the primary coil provided on the charger side in a non-contact manner, is provided in the electric toothbrush body, and the charging is detected by the voltage induced in the secondary coil. 16. The electric toothbrush according to 16. 18. The electric toothbrush according to claim 17, wherein the secondary coil also serves as a charging coil for charging the rechargeable battery.