Nakanishi Dental Mfg. Co., Ltd.

Nakanishi Dental Manufacturing Co., Ltd.

Toshimasa Nakanishi

A dental handpiece having a handle portion, a powerhead assembly integrally and perpendicularly linked to the handle portion, a holding sleeve fixedly inserted in the handle portion, a driving shaft journaled in a bushing in the holding sleeve, the driving shaft including an integral disc at its outer end, the outer end surface of the integral disc being concave, the concave surface carrying at its periphery a guide pin which is directed toward the point of intersection of the axis of the driving shaft and that of a cylindrical hollow driven shaft having a spherical middle portion, the cylindrical driven shaft being rotatably mounted in the powerhead assembly in bushings, the spherical middle portion of the cylindrical driven shaft having a longitudinal concave guide slot and the guide pin being slidably inserted into the longitudinal concave guide slot to couple the driving shaft with the cylindrical driven shaft, and a dental tool on the cylindrical driven shaft, whereby the dental tool is driven so as to rotate in one direction and in the opposite direction alternately by the circular rotation of the driving shaft.

Dental handpiece

The present transmission gear for a dental handpiece generally has a handle portion including a biased guide slot and a holding sleeve fixedly held in the handle portion, a first cylindrical hollow driven shaft, a second driven shaft having at its rear end portion an axial central cavity and fixedly inserted into the first driven shaft, a shiftable clutch shaft having a drive pin, a collar bearing including a slidable pin and a crossed male lug and journaled rotatably in the central hollow, a planetary gear train provided at the rear end portion of the clutch shaft, and a drive gear coupled to the motor to be engaged with the clutch shaft whereby the clutch shaft is either coupled to the drive shaft or disengaged therefrom by the alternative rotation of an operating ring to deliver either a direct transmission of the motor rotation or reduced speed rotation thereof to a dental tool.

Transmission gear for a dental handpiece

A dental handpiece of the present invention is provided with a head extending at substantially a right angle to said handpiece having a hollow therein. The head is also provided with a hollow vertically communicating with the hollow of the handpiece. A semispherical groove is cut into the hollow wall longitudinally and partially adjacent an orifice of the head. A cartridge having an elongated opening cut through at a mid-portion of a bottom thereof and also a small opening at a top wall near a lower orifice and at the same position as the semispherical groove is mounted into its hollow with a rotatable bushing through metal bearings inserted into a lower and upper orifices of the hollow. A gear is secured to the bushing at a position to form an entry into the elongated opening of the cartridge. Together with the spherical groove of the head and the small opening of the cartridge, a semispherical cavity cut into the lower metal bearing defines a spherical space for a metal ball. Accordingly, when the cartridge having a reamer is inserted into the head, the metal ball is fitted in a protruding fashion into the semispherical groove to prevent idling between the gear and metal bearings. The gear secured to the bushing can be easily adapted to mesh with a gear of the driving gear rotatably mounted within the handpiece, thus enabling the dentist to easily exchange the cartridge comprising the worn out parts.

Dental handpiece and a cartridge for a head thereof

A cylindrical member of the present dental handpiece is provided with a cup bearing held into an opening adjacent its upper end and also with an annular bearing disposed into said opening adjacent its lower end. A metallic member having a substantially inclined bottom face is secured to the cup bearing. A top end face of a bushing having a worm wheel is coincidentally inclined to fit to said inclined bottom face of the metallic member so as to form a cam mechanism. The bushing is formed with an annularly widened opening therein adjacent its lower end to receive a collet chuck and also a screw thread around said bushing, which is rotatably inserted into the cylindrical member through the cup and annular bearings. A reamer is firmly held into the bushing through a collet chuck, and a worm gear is associated with the worm wheel. According to the dental handpiece, the reamer is driven to rotate slowly once at its each vertical mot motion, enabling to carry out a finger touch operation.

Growing community of inventors

Kanuma, Japan

Toshimasa Nakanishi