| 摘要 |
PROBLEM TO BE SOLVED: To prevent a push button from being brought into contact with a tool holding means rotating at high speed if the push button is carelessly pressed while a dental hand-piece is used. SOLUTION: An annular groove 12 is formed along the inner circumference of a guide surface 3a on a head cap 3 side for guiding the push button 10 to be pressed, and a resistance member 13 composed of an annular elastic member is retractively fitted into the groove 12. With this structure, air pressure during the rotational driving is divided to be fed to the back side of the annular resistance member 13, and the annular resistance member 13 is made to project into the guide surface 3a with the fed air pressure. Accordingly, even if a user tries to press the push button 10, the push button 10 abuts to the resistance member 13 projecting into the guide surface 3a while the dental hand-piece is rotating, so that the user is prevented from pressing the push button. If the rotation is stopped, air pressure is reduced and the projecting resistance member 13 retracts into the groove with its own elasticity, so that the push button 10 can be pressed to attach/detach a cutting bar 4. COPYRIGHT: (C)2011,JPO&INPIT
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