Nakanishi Dental Mfg. Co., Ltd.

Tadashi Baba

Yuichi Shibata

Norimasa Kaneko

A rotational coupling device for a cordless dental instrument including a motor housing which has a pair of semi-annular projections integrally provided at a rear end thereof with a pair of arc-shaped recesses formed between the coupling projections and semi-annular slot provided around the inner peripheries of the semi-annular projections. A battery housing has a pair of semi-annular around an outer periphery adjacent its front end, a pair of arc-shaped projections coinciding with the arc-shaped recesses of the motor housing and a pair of semi-annular flanges coinciding with the pair of semi-annular projections of the motor housing so as to form a rotational coupling between the motor housing and the battery housing. An insulating disc having a pair of contacts connected to a motor fits into a rear opening of the motor housing. Another insulating disc having a pair of arc-shaped guide slots fits into a forward opening of the battery housing, each slot including a positive contact, a negative contact and a neutral non-contact point which are selectively connected to the pair of contacts of the motor housing. The motor housing has a standard marking, which is rotatably aligned with a normal marking, a reverse marking and a neutral, marking on the battery housing to drive the drive motor in a normal direction, in a reverse direction or to stop the motor, respectively.

Rotational coupling device for a dental handpiece having a built-in

A dental handpiece has a handle portion including a powerhead assembly integrally supported on a front end of the handle portion and a base cylindrical member located in a cylindrical hollow portion of the handle portion. The base cylindrical member has a first axial central passage for a fiberscope, a second side passage for supplying air under pressure, a third side passage for supplying water and a fourth passage for exhaust. A middle connector has a large diameter front hollow portion and a small diameter rear hollow portion having internal threads, three radial openings provided through the connector at equally spaced locations, passages corresponding to the passages in the base cylindrical member and a tubular plunger slidably mounted thereon. A driven ball and a driving ball are slidably located in each radial opening for engaging a circumferential slot around an external rear end portion of a hollow mount insert threadedly fitted into the rear end portion of the base cylindrical member. A rear connector has passages corresponding to those of the base cylindrical member and the middle connector. An electric lamp is located in the larger diameter front hollow portion of the middle connector and has a plurality of fluid pressure passages for removing heat from the electric lamp. The tubular plunger is slidably movable for radially displacing the driven and driving balls to disconnect or assemble the dental handpiece.

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Kanuma, Japan

Tadashi Baba