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EP-4039219-B1 - DENTAL HANDPIECE

EP4039219B1EP 4039219 B1EP4039219 B1EP 4039219B1EP-4039219-B1

Inventors

  • TANAKA, HITOSHI
  • MURATA, TOMOYA
  • NAKAYAMA, SHOZO

Dates

Publication Date
20260506
Application Date
20200821

Claims (6)

  1. A dental handpiece (1) comprising: a main body (5, 6) to be held by a user; and a head (7) connected to the main body (5, 6), wherein the head (7) includes a tool rotating mechanism (50) that holds a cutting tool (3) for operating a region to be operated, rotates based on rotation of a drive unit (2a) that is rotationally driven, and rotates the cutting tool (3), wherein the main body (5, 6) includes a first rotary shaft (22) to which rotation of the drive unit (2a) is transmitted, a second rotary shaft (33) to which rotation of the first rotary shaft (22) is transmitted, and a third rotary shaft (43) to which rotation of the second rotary shaft (33) is transmitted, a first gear mechanism (10A) that increases and transmits rotation of the first rotary shaft (22) to the second rotary shaft (33) is provided between the first rotary shaft (22) and the second rotary shaft (33), a second gear mechanism (10B) that increases and transmits rotation of the second rotary shaft (33) to the third rotary shaft (43) is provided between the second rotary shaft (33) and the third rotary shaft (43), a third gear mechanism (10C) that increases and transmits rotation of the third rotary shaft (43) to the tool rotating mechanism (50) is provided between the third rotary shaft (43) and the tool rotating mechanism (50), the first gear mechanism includes a gear with 23 teeth and a gear with 7 teeth, the second gear mechanism includes a gear with 13 teeth and a gear with 8 teeth, and the third gear mechanism includes a gear with 16 teeth and a gear with 12 teeth.
  2. The dental handpiece (1) according to claim 1, wherein at least one of the first gear mechanism (10A) and the second gear mechanism (10B) includes an internal gear (34) that transmits rotation and an external gear (41) to which rotation is transmitted, the external gear (41) having a smaller diameter than the internal gear (34).
  3. The dental handpiece (1) according to claim 2, wherein a tooth (41b) of the external gear (41) is configured such that a tooth surface has an arc protruding toward a radially outer side of the external gear (41).
  4. The dental handpiece (1) according to any one of claims 1 to 3, wherein the main body (5, 6) includes a substantially cylindrical first main body provided with the second rotary shaft (33) and a substantially cylindrical second main body provided with a distal end of the third rotary shaft (43), and the second main body has a head side smaller in diameter than the first main body side.
  5. The dental handpiece (1) according to claim 4, wherein the second rotary shaft (33) and the third rotary shaft (43) form an obtuse angle.
  6. The dental handpiece (1) according to any one of claims 1 to 5, wherein the drive unit (2a) has a maximum rotation speed of 40,000 rpm, and the tool rotating mechanism (50) has a maximum rotation speed of 285,000 rpm.

Description

Technical Field The present invention relates to a dental handpiece that holds a cutting tool for cutting caries, which is an affected part, and rotates the cutting tool at a high speed in the field of dental treatment. Background Art As a cutting instrument in the field of dental treatment, a motor handpiece that cuts caries which is an affected part of a patient by a drive force of a motor, or an air turbine handpiece that cuts caries by a rotational force of an air turbine is known. These handpieces can cut a tooth by rotating a cutting tool held by a chuck provided inside a head at a high speed. The faster the revolution speed (rpm) of the cutting tool per minute, that is, the higher the rotation speed, the smoother a tooth can be cut. However, although the rotation of the cutting tool by a typical motor used in the motor handpiece has rotational torque as compared with the rotation of the air turbine handpiece, high-speed rotation as in the air turbine handpiece cannot be obtained. As such, for example, in the motor handpiece disclosed in Patent Literature 1, two speed-increasing gear mechanisms are provided in a rotation transmission mechanism that transmits the rotation of a motor to a cutting tool, to accelerate the rotation of the motor and rotate the cutting tool at a high speed. This allows a smooth cutting of a tooth. However, even with the conventional motor handpiece devised to increase the speed as described above, a sufficient rotation speed for efficiently cutting a tooth cannot be obtained, and further increase in the rotation speed is desired. Citation List Patent Literature Patent Literature 1: JP 2009-28512 A Further technological background can be found in US 2009/004622 A1 and JP 2015 006488 A. Summary of Invention Technical Problem In view of the above problem, an object of the present invention is to provide a dental handpiece capable of rotating a cutting tool at a high speed as compared with the conventional technique. Solution to Problem The invention is set out in the appended set of claims. The present invention is a dental handpiece including a main body to be held by a user and a head connected to the main body, wherein the head includes a tool rotating mechanism that holds a cutting tool for operating a region to be operated, rotates based on rotation of a drive unit that is rotationally driven, and rotates the cutting tool, and the tool rotating mechanism has a rotation speed of at least 5.5 times or more a rotation speed of the drive unit. The rotation speed is also referred to as revolution speed per unit time. As an aspect of the present invention, the main body includes a first rotary shaft to which rotation of the drive unit is transmitted, a second rotary shaft to which rotation of the first rotary shaft is transmitted, and a third rotary shaft to which rotation of the second rotary shaft is transmitted, a first gear mechanism that transmits rotation of the first rotary shaft to the second rotary shaft is provided between the first rotary shaft and the second rotary shaft, a second gear mechanism that transmits rotation of the second rotary shaft to the third rotary shaft is provided between the second rotary shaft and the third rotary shaft, and a third gear mechanism that transmits rotation of the third rotary shaft to the tool rotating mechanism is provided between the third rotary shaft and the tool rotating mechanism. As an aspect of the present disclosure, the first gear mechanism may transmit rotation of the drive unit to the second rotary shaft such that a rotation speed of the second rotary shaft becomes 1.64 to 4.50 times a rotation speed of the drive unit transmitted to the first rotary shaft, the second gear mechanism may transmit rotation of the drive unit to the third rotary shaft such that a rotation speed of the third rotary shaft becomes 1.00 to 2.43 times the rotation speed of the second rotary shaft, and the third gear mechanism may transmit rotation of the drive unit to the tool rotating mechanism such that a rotation speed of the tool rotating mechanism becomes 0.80 to 2.00 times the rotation speed of the third rotary shaft, to rotate the cutting tool. The present disclosure may be a dental handpiece including a main body to be held by a user and a head connected to the main body, wherein the main body includes a first rotary shaft to which rotation of a drive unit that is rotationally driven is transmitted, a second rotary shaft to which rotation of the first rotary shaft is transmitted, and a third rotary shaft to which rotation of the second rotary shaft is transmitted, the head includes a tool rotating mechanism that holds a cutting tool for treating a region to be treated, rotates based on rotation of the drive unit, and rotates the cutting tool, the dental handpiece includes: a first gear mechanism that transmits rotation of the first rotary shaft to the second rotary shaft such that a rotation speed of the second rotary shaft becomes 1.64 t