Dental handpiece

Abstract

To reduce a burden on an operator's fingers when attaching and detaching a cutting tool in a dental handpiece.SOLUTION: A dental handpiece according to the present disclosure includes a head, a holding mechanism that holds a cutting tool, and a release mechanism that brings the cutting tool held by the holding mechanism into a released state. The release mechanism includes a cap 71, a cap ring 72 that surrounds an end portion of the holding mechanism, a push cap 73 that covers the cap ring and the end portion and is capable of pressing in a direction in which the holding mechanism is provided, a protrusion that is provided on a surface of the push cap facing the end portion and that brings the holding mechanism into the released state by pressing the end portion, and a wave washer 74 that is provided between the cap ring and the push cap and biases the protrusion in a direction opposite to a direction in which the protrusion presses the end portion. A height difference is provided in a shape of the holding mechanism or the cap ring such that an inner diameter of the wave washer does not come into contact with the holding mechanism or the cap ring.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to dental handpieces. [Background technology]

[0002] 2. Description of the Related Art A dental handpiece is a cutting instrument known in the field of dentistry, which cuts teeth by rotating a chuck provided inside a head at high speed while holding a cutting tool.

[0003] Generally, dental handpieces are provided with a release mechanism that releases the chuck from the outside to remove the cutting tool so that the cutting tool can be attached or detached depending on the treatment content.

[0004] This release mechanism is realized by a configuration in which a push cap is provided on the housing of the head, and the surgeon releases the chuck by pressing the push cap, as disclosed in Japanese Patent No. 4088475 (Patent Document 1), for example. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4088475 Summary of the Invention [Problem to be solved by the invention]

[0006] The push cap is biased by an elastic body in the direction opposite to the cutting edge of the cutting tool. This can put a lot of strain on the surgeon's fingers when pushing the push cap. In such cases, the process of attaching and detaching the cutting tool becomes complicated, and replacing the cutting tool can take a long time.

[0007] The present disclosure has been made in consideration of the above-mentioned problems, and its purpose is to reduce the burden on the operator's fingers when attaching or detaching a cutting tool in a dental handpiece. [Means for solving the problem]

[0008] The dental handpiece of the present disclosure is a dental handpiece that detachably holds a cutting tool and includes a head, a holding mechanism housed in the head and holding the cutting tool, and a release mechanism that releases the cutting tool held by the holding mechanism. The release mechanism includes a cap attached to the face of the head opposite the face where the cutting tool is attached or detached, a cap ring fixed to the cap and surrounding the end of the holding mechanism, a push cap that covers the cap ring and the end and can be pressed in the direction of the holding mechanism, a convex portion provided on the face of the push cap opposite the end and that releases the holding mechanism by pressing the end, and a wave washer provided between the cap ring and the push cap and that biases in the direction opposite to the direction in which the convex portion presses the end, and the shape of the holding mechanism or the cap ring has a height difference so that the inner diameter of the wave washer does not abut against the holding mechanism or the cap ring. [Effects of the Invention]

[0009] According to the present disclosure, the burden on the fingers of the operator when attaching or detaching a cutting tool in a dental handpiece can be reduced. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is an external view showing the appearance of the dental handpiece. [Figure 2] FIG. 2 is a diagram illustrating the internal structure of the head. [Figure 3] FIG. 2 is an exploded perspective view schematically illustrating a release mechanism. [Figure 4] 10A and 10B are diagrams for explaining an increase in load near the close contact point of the wave washer. [Figure 5] FIG. 10 is a cross-sectional view illustrating a state of the release mechanism before the push cap is pushed. [Figure 6] 10 is a cross-sectional view illustrating the state of the release mechanism when the push cap is pressed. FIG. [Figure 7]10 is a diagram showing the relationship between the amount of movement of the push cap and the load. FIG. [Figure 8] FIG. 10 is a cross-sectional view illustrating a release mechanism according to a comparative example. [Figure 9] 10A and 10B are diagrams illustrating the internal structure of a head according to a modified example. [Figure 10] 10A and 10B are diagrams illustrating the internal structure of a head according to another modified example. [Figure 11] FIG. 10 is an external view of a wave washer according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and their description will not be repeated.

[0012] [Dental handpiece configuration] In dental handpieces, when the push cap is pressed by the operator, the cutting tool is released. If the push cap comes into contact with the oral cavity during treatment and the operator unintentionally releases the cutting tool, the cutting tool may come into contact with parts of the oral cavity other than the teeth, potentially causing injury to the oral cavity. Therefore, the push cap is biased by an elastic body in the direction opposite to the direction in which the cutting tool is released, preventing the operator from unintentionally releasing the cutting tool.

[0013] The elastic body that biases the push cap is, for example, a wave washer. A wave washer is a ring-shaped thin plate with a wave-shaped deflection. By using a wave washer as the elastic body, it is possible to bias the push cap without increasing the height of the head.

[0014] When a wave washer is pushed in, its deflection flattens, and stress is applied in the opposite direction to the direction of the push. When the wave washer is pushed in, the area that can deflect is reduced, making the wave washer less likely to deform. Therefore, for example, if a surgeon pushes a push cap and the wave washer comes into close contact with another component, the wave washer cannot deflect, and the load on the push cap increases. In such cases, the strain on the surgeon's fingers when pushing the push cap may increase.

[0015] In the dental handpiece according to the present disclosure, the shape of the holding mechanism or the cap ring is provided with a height difference so that the inner diameter of the wave washer does not abut against the holding mechanism of the cutting tool or the cap ring surrounding the end of the holding mechanism when the surgeon pushes the push cap. This prevents the wave washer from coming into close contact with other components even if it is pushed and deformed. Therefore, even if the push cap is pushed to a position where the cutting tool is released, the wave washer can bend, preventing an increase in the load on the push cap.

[0016] In the first embodiment, an example in which a recess is provided in the holding mechanism or the cap ring will be described. In the first embodiment, the recess provided in the holding mechanism or the cap ring is an example of providing a height difference in the shape of the holding mechanism or the cap ring.

[0017] FIG. 1 is an external view showing the appearance of a dental handpiece 1 according to the first embodiment. Referring to FIG. 1, the dental handpiece 1 according to the first embodiment is configured to detachably hold a cutting tool 3 and rotate the cutting tool 3 at high speed. In the first embodiment, the dental handpiece 1 is an air turbine handpiece that rotates the cutting tool 3 at high speed using an air turbine. The dental handpiece 1 may also be a motor handpiece that rotates the cutting tool 3 at high speed using a motor.

[0018] A driving unit 2 is connected to one longitudinal end (base end) of the dental handpiece 1. The driving unit 2 is configured to be detachable from the base end of the dental handpiece 1. The driving unit 2 supplies driving air to the head. A cutting tool 3 is held at the other longitudinal end (tip end) of the dental handpiece 1. The cutting tool 3 is configured to be able to cut teeth by rotating.

[0019] The dental handpiece 1 includes a body 4, a neck 5, and a head 6. The body 4, neck 5, and head 6 are arranged in this order from the base end to the tip end in the longitudinal direction of the dental handpiece 1.

[0020] The body 4 is configured to be detachable from the drive unit 2. The body 4 is disposed on the base end side of the dental handpiece 1. The diameter of the body 4 gradually decreases toward the tip end side of the dental handpiece 1. The body 4 has a substantially cylindrical housing. The body 4 is the part that is held by users such as practitioners and maintenance workers.

[0021] When the practitioner holds the dental handpiece 1 with the cutting tool 3 downward, the head 6 upward, and the body 4 horizontal, the neck 5 bends upward in the longitudinal center. The diameter of the neck 5 gradually decreases toward the tip of the dental handpiece 1. The neck 5 has a substantially cylindrical housing.

[0022] The head 6 is connected to the body 4 via the neck 5. The head 6 has a substantially cylindrical housing whose axial direction is substantially perpendicular to the longitudinal direction of the neck 5 (the vertical direction in FIG. 1).

[0023] Fig. 2 is a cross-sectional view illustrating the internal structure of the head 6. Referring to Fig. 2, the head 6 includes a rotary vane 61, a release mechanism 7, and a holding mechanism 8. The head 6 rotates the cutting tool 3 held by the holding mechanism 8 by the rotation of the rotary vane 61, which rotates upon receiving driving air supplied from the driving unit 2.

[0024] The holding mechanism 8 holds the cutting tool 3. The holding mechanism 8 has a rotating cylinder 81, a slide ring 82, a ring holder 83, a chuck 84, an elastic body 85, a capsule cap 86, and an end portion 87.

[0025] The slide ring 82, the ring holder 83, the chuck 84, and the elastic body 85 are inserted into the rotary cylinder 81. The chuck 84, the elastic body 85, the slide ring 82, and the ring holder 83 are housed inside the rotary cylinder 81 in this order from the cutting edge side to the base side of the cutting tool 3.

[0026] The rotary cylinder 81 is configured so that the cutting tool 3 can be inserted therein. The rotary cylinder 81 is formed in a cylindrical shape, and rotates around an axis along the longitudinal direction of the cutting tool 3 as the rotation axis when the rotary vanes 61 rotate.

[0027] The chuck 84 is configured to be able to detachably mount the cutting tool 3 inserted into the rotary cylinder 81. The chuck 84 is disposed inside the rotary cylinder 81, closer to the cutting edge (lower) than approximately the center in the longitudinal direction of the cutting tool 3. The chuck 84 holds the base shaft of the cutting tool 3 inserted along the longitudinal direction of the cutting tool 3.

[0028] The elastic body 85 is configured to bias the chuck 84 so that the chuck 84 engages with the cutting tool 3. When pressed by the slide ring 82, the elastic body 85 is compressed toward the cutting edge of the cutting tool 3. This makes it possible to remove the cutting tool 3 from the chuck 84.

[0029] The slide ring 82 is configured to be able to move in the axial direction inside the rotary cylinder 81. The slide ring 82 is accommodated on the cutting tool 3 base side relative to the elastic body 85, and is configured to be able to press the elastic body 85.

[0030] The ring holder 83 has a substantially ring shape and is provided on the blade base side of the slide ring 82. The ring holder 83 can regulate the position of the cutting tool 3 when the cutting tool 3 is attached.

[0031] The capsule cap 86 covers the side of the rotary barrel 81 opposite to the cutting edge side of the cutting tool 3. A hole is formed in the center of the capsule cap 86. A recess 86a is formed on the surface of the capsule cap 86 facing the push cap 73. The recess 86a will be described in detail later.

[0032] The end portion 87 is formed on the opposite side to the cutting edge side of the cutting tool 3 inside the rotary cylinder 81. The end portion 87 is connected to the slide ring .

[0033] In the holding mechanism 8, the elastic body 85 before being compressed and deformed presses the end of the chuck 84 on the blade base side, and the chuck 84, which has been reduced in diameter by the pressure of the elastic body 85, can hold the cutting tool 3. On the other hand, when the slide ring 82 moves due to the end 87 being pressed and the elastic body 85 is compressed and deformed, the holding of the cutting tool 3 by the chuck 84 can be released. The state in which the holding mechanism 8 can release the cutting tool 3 is referred to as the holding mechanism 8 being in a released state.

[0034] The release mechanism 7 releases the holding mechanism 8. The release mechanism 7 has a cap 71, a cap ring 72, a push cap 73, and a wave washer 74.

[0035] The cap 71 is attached to the surface of the head 6 opposite to the surface where the cutting tool 3 is attached and detached.

[0036] The cap ring 72 is fixed to the cap 71. The cap ring 72 is provided so as to surround the capsule cap 86 and the end portion 87.

[0037] The push cap 73 covers the cap ring 72 and the end portion 87, and is configured so that it can be pressed in the direction in which the holding mechanism 8 is provided. The push cap 73 has a protrusion 73a that protrudes in the direction in which the holding mechanism 8 is provided. When the push cap 73 is pressed in the direction in which the holding mechanism 8 is provided, the push cap 73 moves in the direction in which the holding mechanism 8 is provided, and the protrusion 73a presses the end portion 87. When the end portion 87 is pressed, the holding mechanism 8 enters a released state.

[0038] The wave washer 74 is provided between the cap ring 72 and the push cap 73. The wave washer biases the push cap 73 in the direction opposite to the direction in which the protrusion 73a presses the end portion.

[0039] Fig. 3 is an exploded perspective view illustrating the configuration of the release mechanism 7. As shown in Fig. 3, a cap ring 72 is fixed to a cap 71, and a push cap 73 is coupled to the cap 71 so as to cover the cap ring 72. A wave washer 74 is provided between the cap ring 72 and the push cap 73.

[0040] 3, wave washer 74 has a protrusion 74a that protrudes toward push cap 73 and a protrusion 74b that protrudes away from push cap 73. When protrusions 74a and 74b are crushed and deformed flat, an elastic force is generated that causes them to return to their original shape.

[0041] [Relationship between pressing amount and load for wave washers] FIG. 4 is a diagram for explaining the relationship between the pressing amount and the load in the wave washer.

[0042] FIG. 4 shows the magnitude of the load that flat plate X receives from wave washer Z when wave washer Z is sandwiched between flat plates X and Y and crushed.

[0043] The surfaces of plates X and Y are flat. The case where an object is crushed between plates X and Y is called the case where there is no space.

[0044] When flat plate X is pushed and displaced, wave washer Z comes into close contact with flat plate X and flat plate Y. The amount of displacement of flat plate X when wave washer Z comes into close contact with flat plate X and flat plate Y is V. Figure 4 shows the state of flat plate X, flat plate Y, and wave washer Z when the amount of displacement of flat plate X is V. When there is no space, wave washer Z comes into close contact with flat plate X and flat plate W, as shown from views A and B in Figure 4.

[0045] As the wave washer is pressed in, the area that can bend becomes smaller. As the area that can bend becomes smaller, the wave washer becomes less likely to deform, and the load relative to the amount of pressing becomes larger. As shown in Figure 4, when the displacement of plate X exceeds V, the increase in load relative to the displacement of plate X increases.

[0046] Figure 4 also shows the magnitude of the load that flat plate X receives from wave washer Z when wave washer Z is sandwiched and crushed between flat plates X and W. Flat plate W has a circular hole H that is smaller than the outer diameter of wave washer Z but larger than the inner diameter. In Figure 4, the case where flat plates X and W sandwich and crush wave washer Z is represented as a case where there is a gap.

[0047] When there is a space, even if the displacement of the flat plate X exceeds V, the magnitude of the load that the flat plate X receives from the wave washer Z changes almost linearly.

[0048] This is because, as shown in views A and B when there is a space in Figure 4, when wave washer Z is sandwiched between flat plate X and flat plate W and crushed, part of the inner diameter of wave washer Z protrudes into hole H formed in flat plate W, allowing the wave washer to bend further. When there is a space, particularly as seen in view B, part of the inner diameter of wave washer Z enters hole H formed in flat plate W, and wave washer Z does not come into close contact with flat plate X and flat plate W. Therefore, by using flat plate W, it is possible to prevent a sudden increase in the amount of change in the magnitude of the load on the wave washer.

[0049] [Avoiding adhesion of wave washers in the released state] 5 and 6, the state of the wave washer 74 when the holding mechanism 8 is in the released state in the dental handpiece 1 according to this embodiment will be described. Fig. 5 is a cross-sectional view showing the state of the release mechanism 7 when the push cap 73 is not pressed. Fig. 6 is a cross-sectional view showing the state of the release mechanism 7 when the push cap 73 is pressed.

[0050] Referring to FIG. 5, the recess 86a is formed at a position corresponding to the inner diameter of the wave washer 74.

[0051] 5, when the push cap 73 is not pressed, the protrusion 74a of the wave washer 74 abuts against the push cap 73. In this state, the protrusion 74b of the wave washer 74 abuts against the cap ring 72.

[0052] When the push cap 73 is pressed toward the holding mechanism 8, the wave washer 74 is deformed. Specifically, the protrusions 74a and 74b are deformed so as to approach a flat state. As a result, a repulsive force is generated in the wave washer 74. This repulsive force applies a load to the push cap 73 on the side opposite to the surface on which the holding mechanism 8 is located.

[0053] When the push cap 73 is pressed further, the convex portion 73a of the push cap 73 is pressed against the holding mechanism 8, as shown in Fig. 6. Although not shown in Fig. 6, at this time, the convex portion 73a presses the end portion 87 of the holding mechanism 8. This causes the chuck 84 of the holding mechanism 8 to release the cutting tool 3, allowing the surgeon to remove the cutting tool 3.

[0054] 6, when the retention mechanism 8 is in the released state, the wave washer 74 deforms so that the inner diameter of the wave washer 74 enters the recess 86a. As a result, when the retention mechanism 8 is in the released state, the wave washer 74 does not come into close contact with the cap ring 72 and the capsule cap 86. Therefore, by providing the recess 86a, the dental handpiece 1 can prevent the wave washer 74 from coming into close contact with the cap ring 72 and the capsule cap 86 when the wave washer 74 is crushed by the push cap 73.

[0055] [Load magnitude relative to push cap movement] 7 and 8, the change in the magnitude of the load on the push cap 73 when the surgeon pushes in the push cap 73 will be described. FIG. 7 is a diagram showing the magnitude of the load relative to the amount of movement of the push cap 73. FIG. 8 is a cross-sectional view for explaining the dental handpiece shown as a comparative example in FIG. 7. The magnitude of the load on the push cap 73 when the surgeon pushes in the push cap 73 corresponds to the magnitude of the strain on the surgeon's fingers.

[0056] In the dental handpiece 1 according to the first embodiment and the dental handpiece according to the comparative example, when the amount of movement of the push cap reaches R, the holding mechanism is released.

[0057] As shown in Fig. 7, the magnitude of the load applied to the push cap 73 in the dental handpiece 1 according to the first embodiment does not increase significantly until the amount of movement of the push cap 73 reaches R. As shown in Fig. 7, when the holding mechanism 8 of the dental handpiece 1 according to the first embodiment is released, a force of W1 is applied to the operator's finger.

[0058] The capsule cap 88 of the dental handpiece according to the comparative example shown in Fig. 8 does not have a recess 811. Therefore, when the push cap 73 is pressed, the wave washer 74 comes into close contact with the capsule cap 88. As shown as a comparative example in Fig. 7, the magnitude of the load on the push cap 73 according to the comparative example increases before the amount of movement of the push cap 73 reaches R. As shown in Fig. 7, when the holding mechanism of the dental handpiece according to the comparative example is released, a force W2 larger than W1 is applied to the operator's finger.

[0059] As described above, in the dental handpiece 1 according to the first embodiment, it is possible to reduce the burden on the operator's fingers when the holding mechanism 8 is released.

[0060] [Variation 1] In the first embodiment, an example in which the capsule cap has a recess is described. In the first modification, an example in which a recess corresponding to a height difference provided in the shape of the holding mechanism or the cap ring is provided in the cap ring so that the inner diameter of the wave washer does not abut against the holding mechanism or the cap ring is described.

[0061] Fig. 9 shows a cross-sectional view of a dental handpiece according to Modification 1. Referring to Fig. 9, a cap ring 75 according to Modification 1 has a recess 75a.

[0062] When the push cap 73 is pressed and the holding mechanism 8 is released, the wave washer 74 deforms so that the inner diameter of the wave washer 74 enters the recess 75a. As a result, when the holding mechanism 8 is released, the wave washer 74 does not come into close contact with the cap ring 72 and the capsule cap 86. Therefore, by providing the recess 75a to the dental handpiece 1, the wave washer 74 can bend when it is crushed by the push cap 73.

[0063] In the dental handpiece 1 according to the first embodiment, the recesses are annular, but are not limited thereto. For example, if the position of the wave washer is fixed inside the head, the recesses may be provided only at positions corresponding to the inner diameter of the protrusions of the wave washer.

[0064] Furthermore, in the dental handpiece 1 according to the first embodiment described above, the recess is provided at a position corresponding to the inner diameter of the wave washer, but this is not limited thereto, and the recess may be provided at a position corresponding to the outer diameter of the wave washer.

[0065] [Variation 2] In the above-described first embodiment and first modification, an example was described in which a recess is provided in the retaining mechanism or the cap ring as an example of a height difference provided in the shape of the retaining mechanism or the cap ring to prevent the inner diameter of the wave washer from contacting the retaining mechanism or the cap ring. In the second modification, an example is described in which a height difference is provided in the shape of the retaining mechanism or the cap ring between the surface where the cap ring and the wave washer contact and the surface of the retaining mechanism that covers the end portion.

[0066] Fig. 10 shows a cross-sectional view of a dental handpiece according to Modification 2. Referring to Fig. 10, the surface of capsule cap 89 according to Modification 2 facing push cap 73 is spaced apart from push cap 73 compared to the surface of capsule cap 86 according to Embodiment 1 facing push cap 73.

[0067] 10 , the surface where the wave washer 74 and cap ring 72 come into contact is separated by a length L from the surface of the capsule cap 89 that faces the push cap 73. If the length L is equal to or greater than a predetermined value determined by the outer and inner diameters of the wave washer 74, the inner diameter of the wave washer 74 can be prevented from coming into contact with the holding mechanism 8 when the wave washer 74 is crushed. This predetermined value is, for example, 10% of half the difference between the outer and inner diameters of the wave washer 74.

[0068] According to the present disclosure, a height difference is provided in the shape of the retaining mechanism or the cap ring so that the inner diameter of the wave washer does not abut against the retaining mechanism or the cap ring. This height difference prevents the wave washer from coming into close contact with the retaining mechanism or the cap ring, thereby reducing the strain on the surgeon's fingers.

[0069] Furthermore, according to the present disclosure, the stress that the cap ring and capsule cap receive from the wave washer can be reduced, thereby reducing wear on the cap ring and capsule cap and improving the durability of the dental handpiece.

[0070] It should be noted that simply using a wave washer with a small spring constant can reduce the burden on the surgeon's fingers. However, if a wave washer with a small spring constant is used, the push cap may come into contact with the oral cavity during treatment, causing the cutting tool to be released at a time unintended by the surgeon. Therefore, it may be difficult to use a wave washer with a small spring constant to reduce the burden on the surgeon's fingers. According to the present disclosure, it is possible to suppress an increase in the load near the contact point while maintaining the magnitude of the spring force applied to the push cap at the beginning of pressing.

[0071] [Embodiment 2] In the first embodiment, it has been explained that the increase in load occurring near the contact point of the wave washer is reduced by providing a space into which part of the inner diameter of the wave washer enters when the wave washer is pressed.

[0072] In the second embodiment, a dental handpiece will be described in which the shape of the wave washer is changed to reduce the increase in load occurring near the contact point of the wave washer.

[0073] In the first embodiment, when wave washer 74 is pressed, convex portion 74b is first flattened. Then, when wave washer 74 is further pressed, convex portion 73a is flattened. Therefore, the load applied to push cap 73 in the first half of the pressing period is based on the stress of convex portion 74b attempting to return to its original shape, and the load applied to push cap 73 in the second half of the pressing period is based on the stress of convex portion 74a attempting to return to its original shape.

[0074] In the wave washer according to the second embodiment, the difference between the outer diameter and the inner diameter of the wave washer at the convex portion that protrudes away from the push cap is smaller than the difference between the outer diameter and the inner diameter of the wave washer at the convex portion that protrudes toward the push cap. This makes it possible to reduce the load on the push cap in the latter half of the pressing period, thereby reducing the strain on the operator's fingers while maintaining the magnitude of the spring force on the push cap at the beginning of pressing.

[0075] Fig. 11 is a diagram showing an example of a wave washer according to embodiment 2. Referring to Fig. 11, wave washer 9 has an outer diameter 91 that is circular and an inner diameter 92 that is elliptical. Width 93 corresponds to the convex portion that protrudes toward the push cap. Width 94 corresponds to the convex portion that protrudes away from the push cap.

[0076] As shown in FIG. 11, width 94 is smaller than width 93. The force generated when the wave washer is crushed depends on the difference between the outer diameter and the inner diameter of the wave washer. Therefore, in wave washer 9, the load applied to the push cap in the latter half of the pressing period is smaller than the load applied to the push cap in the first half of the pressing period.

[0077] By providing the wave washer 9, the dental handpiece can reduce the strain on the operator's fingers while maintaining the magnitude of the spring force acting on the push cap at the beginning of pushing.

[0078] 11 illustrates a wave washer having a circular outer diameter and an elliptical inner diameter. This is an example of a wave washer in which a plurality of first protrusions and a plurality of second protrusions protruding on the opposite side of the plurality of first protrusions are alternately formed in the circumferential direction, and the difference between the outer diameter and the inner diameter of each of the plurality of first protrusions is shorter than the difference between the outer diameter and the inner diameter of each of the plurality of second protrusions. Therefore, the shape of the wave washer in embodiment 2 is not limited to this. For example, the wave washer in embodiment 2 may have an elliptical outer diameter and a circular inner diameter.

[0079] The dental handpiece 1 described in the first embodiment may also include a wave washer having the shape described in the second embodiment.

[0080] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0081] 1 Dental handpiece, 2 Drive unit, 3 Cutting tool, 4 Body, 5 Neck, 6 Head, 7 Release mechanism, 8 Holding mechanism, 9, 74 Wave washer, 61 Rotating blade, 71 Cap, 72, 75 Cap ring, 73 Push cap, 81 Rotating cylinder, 82 Slide ring, 83 Ring holder, 84 Chuck, 85 Elastic body, 86, 88, 89 Capsule cap, 87 End.

Claims

1. A dental handpiece that removably holds a cutting tool, comprising: Head and a holding mechanism housed in the head and holding the cutting tool; a release mechanism for releasing the cutting tool held by the holding mechanism, The release mechanism includes: a cap attached to a surface of the head opposite to a surface where the cutting tool is attached and detached; a cap ring fixed to the cap and surrounding an end of the retention mechanism; a push cap that covers the cap ring and the end portion and can be pressed in a direction in which the holding mechanism is provided; a protrusion provided on a surface of the push cap facing the end portion, the protrusion pressing the end portion to release the holding mechanism; a wave washer provided between the cap ring and the push cap, and biasing the end portion in a direction opposite to the direction in which the protrusion presses the end portion; A dental handpiece, wherein the retaining mechanism or the cap ring has a height difference in its shape so that the inner diameter of the wave washer does not come into contact with the retaining mechanism or the cap ring.

2. 2. The dental handpiece according to claim 1, wherein the height difference provided in the shape of the holding mechanism or the cap ring is 10% or more of half the difference between the outer diameter and the inner diameter of the wave washer.

3. 2. The dental handpiece according to claim 1, wherein the holding mechanism having a height difference is a recess provided on the side of the end portion.

4. The holding mechanism includes a capsule cap provided on the end portion side, The dental handpiece of claim 3 , wherein the recess is provided in the capsule cap.

5. 2. The dental handpiece according to claim 1, wherein the cap ring has a shape with a height difference, the shape being a recess provided on the side of the end portion.

6. In the wave washer, a plurality of first protrusions and a plurality of second protrusions protruding on an opposite side to the plurality of first protrusions are alternately formed in a circumferential direction, 4. The dental handpiece according to claim 1, wherein a difference between an outer diameter and an inner diameter of each of the plurality of first protrusions is smaller than a difference between an outer diameter and an inner diameter of each of the plurality of second protrusions.

7. The dental handpiece according to claim 6 , wherein the plurality of first protrusions protrude toward the push cap, and the plurality of second protrusions protrude toward the cap ring.

8. The dental handpiece of claim 7 , wherein the inner diameter of the wave washer is generally oval and the outer diameter of the wave washer is generally circular.

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