JPH07163584A - Microengine for dental purpose and driving circuit therefor - Google Patents

Abstract

PURPOSE:To cut a tooth by means of a cutting tool freely attachably and detachably mounted at a revolving shaft of a rotor having a pair of magnetic poles N and S symmetrically with the revolving shaft by rotatably disposing this rotor into a head case, disposing >=3 pieces of plural driving coils facing the peripheral surface of the rotor and successively energizing the driving coils, thereby rotating the rotor. CONSTITUTION:A micromotor M is disposed within the head case 2 and the cutting means is freely attachably and detachably mounted at the revolving shaft of the micromotor M to execute cutting, etc., of the tooth. The micromotor M consists of >=3 pieces of odd numbers of coils 31, 32, 33 which are successively pulse driven. The rotor 4 has a pair of the axisymmetrical magnetism and the one magnetic pole moves in follow up to the magnetic pole generated by the coils. Reverse electromotive force is generated at the time of rotating of the rotor 4 in the other coils which are not excited and, therefore, the position of the rotor 4 is detected by detecting the electromotive force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dental microengine, and more particularly to improvement of a microengine used for cutting teeth in dental treatment, and more particularly, to enable the microengine to be incorporated in a head case. A micro engine having a novel structure.

[0002]

2. Description of the Related Art In dental treatment, for cutting teeth,
An air turbine or a micro engine is used.
As is well known, an air turbine is provided with a rotary shaft having turbine blades in a head case, blows air to the turbine blades to rotate the rotary shaft at high speed, and is removably attached to the rotary shaft. The cutting tool is used to cut teeth. On the other hand, the micro engine has a micro motor in the grip case, transmits the rotation of the motor to a rotary shaft arranged in the head case via a spindle or the like, and is detachably mounted on the rotary shaft. The tooth is cut by a cutting tool that is used.

[0003]

However, the air turbine is noisy due to the wind noise of the turbine blades, the noise when air leaks to the outside, etc. Scattered, and even when stopped,
Turbine blades idle and negative pressure is generated inside the head case, dust is sucked into the head case and it is unsanitary.Furthermore, air flushing must be performed to blow out the sucked dust. There were various problems that had to be solved, such as "No". Further, the micro engine requires a power transmission mechanism such as a spindle in order to transmit the rotation of the motor in the grip case to the rotary shaft in the head case, and further increases the rotational speed of the rotary shaft. There is a problem that many members are required such as a speed mechanism, and not only the structure is plural but also the cost is high.

The present invention has been made in view of the above-mentioned circumstances, and in particular, has been made for the purpose of collectively solving the problems of conventional air turbines and micro engines.

[0005]

In order to solve the above-mentioned problems, the present invention provides (1) a rotor rotatably arranged in a head case and having a rotationally symmetrical magnetic pole, and the inside of the head case. And an odd number of drive coils of 3 or more, which are sequentially disposed so as to face the rotating peripheral surface of the rotor, and the drive coils are sequentially excited to rotate the rotor. Or (2) a microprocessor (MPU) or an arithmetic circuit that calculates appropriate power from a plurality of drive pulse fixed data and back electromotive force, and a back electromotive force generated from an external signal or voltage and the drive coil. And sequentially switching the electric power supplied to the drive coil by the microprocessor and controlling the electric energy, or (3) sequentially exciting one of the drive coils to excite the rotor. The magnetic pole is rotated while following the movement of the magnetic pole, and the other magnetic pole (S or N) on the rotor is symmetrically arranged facing one magnetic pole (N or S) on the rotor that follows the exciting magnetic pole. The back electromotive force induced in a pair of drive coils facing each other in the front-back direction of the rotation direction of the rotor is detected, the rotational position of the rotor is detected by the back electromotive force, and the excitation of the drive coil of the rotor is sequentially switched. It is characterized by what was done.

[0006]

[Function] A pair of magnetic poles N, which are symmetrical about the axis of rotation in the head case,
A rotor having S is rotatably disposed, an odd number of drive coils of 3 or more is disposed so as to face the peripheral surface of the rotor, and the drive coils are sequentially excited to rotate the rotor. Tooth is cut with a cutting tool that is detachably attached to the rotating shaft of the rotor.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an overall perspective view and an exploded view of essential parts for explaining an embodiment of a micro engine according to the present invention.
In the figure, 1 is a grip case portion, 2 is a head case portion, and in the present invention, a micro motor M including a stator 3, a rotor 4, bearings 5 and 6 is housed in the head case portion 2. A cutting tool is detachably attached to the rotary shaft 4a of the micromotor.

For example, the rotary shaft 4a has a slit at one end of a tubular body, and the chuck member whose inner diameter changes by changing the opening degree of the slit, and the slit of the chuck member. An opening / closing member for changing the opening degree is housed, and as is well known, a mechanism for pressing the lid member to move the opening / closing member up and down to open / close the chuck member is housed.

The stator 3 has an odd number of coils 3 ₁ , 3 ₂ , 3 ₃ ( _{3 in the} illustrated example) of 3 or more in the circumferential direction,
These coils 3 ₁ , 3 ₂ , 3 ₃ are sequentially excited, and the magnetic poles of N or S poles rotate in the circumferential direction. Further, the rotor 4 is composed of a permanent magnet having a pair of magnetic poles N and S which are axially symmetrical, and as described above, when the coils of the stator 3 are sequentially excited, the S or N pole of the permanent magnet (rotor) is changed. It moves and rotates following the movement of the magnetic pole N or S generated by the excitation of the coil.

FIG. 2 is a diagram showing the relationship between the magnetic poles of the stator 3 and the rotor 4 as described above. As shown in FIG.
Are coils 3 ₁ , 3 ₂ , 3 ₃ arranged in a cylindrical shape, and these coils 3 ₁ , 3 ₂ , 3 ₃ are sequentially pulse-driven, and the N (or S) pole is inside the stator 3 and the outside is outside. An S (or N) pole is generated. Now, taking the case where the N pole is generated on the inside as an example, the coil 3 ₁ is excited, the magnetic pole N ₁ is generated in the stator 3 by the coil 3 _1, stator 4 to the magnetic pole N ₁ Of the rotor 4 is pulled, and the S pole of the rotor 4 faces the coil 3 ₁ as shown in the figure. At this time, the N pole of the rotor 4 is
It is at the boundary point between the coils 3 ₂ and 3 ₃ .

Next, when the coil 3 ₂ is excited, a magnetic pole N ₂ is generated by the coil 3 ₂ , and the S pole of the rotor 4 is attracted by the magnetic pole N ₂ and moves (rotates) in the direction of arrow A. At this time, the N pole of the rotor 4 also moves at the same time, but at that time, a counter electromotive force is generated in the coils 3 ₂ and 3 ₃ . Therefore, the rotational position of the rotor 4 can be detected by detecting this counter electromotive force. This relationship holds when the number of coils is an odd number of 3 or more, such as when there are 5 coils and when there are 7 coils. In this way, if the counter electromotive force generated in the pair of coils on the side facing the exciting coil is detected to detect the rotational position of the rotor, without providing a sensor for detecting the rotational position of the rotor, The rotational position of the rotor can be detected. When the rotational position of the rotor can be detected, the coil to be excited next can be determined. In the illustrated example, when the counter electromotive force of the coils 3 ₂ and 3 ₃ is detected and then the coil 3 ₂ is excited, the rotor 4 is excited. Continue to rotate, then coils 3 ₃ , 3 ₁
The coil 3 ₃ is excited after the back electromotive force of 1 is detected. In the same manner, the rotor 4 can be rotationally controlled by sequentially exciting the coils 3 ₁ , 3 ₂ , 3 ₃ in the same manner, and the rotational speed of the rotor can be controlled by changing the cutting speed of the excitation. it can.

FIG. 3 is a diagram showing an example of an electric circuit for controlling a micro engine based on the above-mentioned principle. In the figure, 10 is a variable resistor (foot controller) and 11 is A / D conversion. Reference numeral 12 is a microprocessor MPU, which changes the resistance value of the variable resistor 10 by a foot operation to change the digital value of the A / D converter 11 to the MPU 12
Read, and the MPU 12 generates a drive signal for the motor driver circuit 13 according to the digital value.

The motor driver circuit 13 receives the drive signals sequentially generated from the MPU 12 according to the program, and sequentially generates the exciting pulses to be supplied to the coils 3 ₁ , 3 ₂ , 3 ₃ of the stator 3 of the motor M, and In this way, the rotor 4 is rotated. When the rotor 4 rotates, the counter electromotive force is generated in the pair of unexcited coils as described above.
Detected by and supplied to the MPU 12. MPU12
Supplies a signal for driving the coil to be excited next to the motor driver circuit 13 based on the detection signal from the rotor rotational position sensor 14, and thereafter, the same operation as described above is repeated to control the rotation of the motor M. .

[0014]

As is apparent from the above description, according to the present invention, since the micromotor is arranged in the head case of the handpiece, the dental treatment is performed with the same feeling as that of the conventional air turbine. be able to. Moreover,
Suction by noise and negative pressure, like an air turbine,
Alternatively, there is no scattering of cutting powder fog. Further, as compared with the conventional micro engine, it is possible to reduce the weight and cost without requiring a power transmission means such as a spindle.

[Brief description of drawings]

FIG. 1 is an exploded view of a motor in a grip case portion and a head case portion for explaining an embodiment of a micro engine according to the present invention.

FIG. 2 is a diagram for explaining a rotation operation of the motor and a rotor position detection operation shown in FIG.

FIG. 3 is a diagram for explaining an example of an electric circuit for controlling rotation of the motor shown in FIGS. 1 and 2.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Gripping case part, 2 ... Head case part, 3 ... Stator, 4 ... Rotor, 5,6 ... Bearing, 7 ... Lid member, 1
0 ... Variable resistor (foot controller), 11 ... A / D
Converter, 12 ... MPU, 13 ... Motor driver circuit,
14 ... Rotor rotational position sensor, M ... Micromotor.

Claims (3)

[Claims] 1. A head case is rotatably disposed in the head case,
And a rotor having rotationally symmetrical magnetic poles, and an odd number of drive coils of 3 or more, which are disposed in the head case and are sequentially disposed so as to face the rotational peripheral surface of the rotor,
A dental micro engine characterized in that the drive coil is sequentially excited to rotate the rotor. 2. A microprocessor (MPU) or an arithmetic circuit for calculating an appropriate power from a plurality of fixed drive pulse data and a back electromotive force, and reading a signal or voltage from the outside and a back electromotive force generated from a drive coil. 2. The microprocessor controls sequential switching of power supplied to the drive coil and control of the amount of power.
A drive circuit for a dental micro-engine according to. 3. One of the drive coils is sequentially excited to cause the rotor to rotate following the movement of the exciting magnetic pole, and one of the magnetic poles (N or S) on the rotor that follows the exciting magnetic pole. The counter electromotive force induced in the pair of drive coils facing each other in the front-back direction of the rotation direction of the other magnetic pole (S or N) on the rotor that is symmetrically arranged to face is detected. The drive circuit for a dental micro engine according to claim 1, wherein the rotational position of the rotor is detected and the excitation of the drive coil of the rotor is sequentially switched.