Dental handpiece

Abstract

A dental handpiece comprising a body portion and a forward tool receiving end portion and detachably attached to said body portion. The body portion has an axial bore with an axial slot in the inner surface thereof and a lateral recess in the slot, and the forward end portion has a shaft with an engaging pin thereon. The shaft is inserted into the axial bore with the pin sliding in the slot, and the shaft is turned to engage the pin in the recess for secure connection of the two portions of the handpiece.

Description

This invention relates to a dental handpiece and more particuraly to a mechanism for connecting the forward end portion of a dental handpiece to the body portion thereof.

As is well known, the dental handpiece comprises a body portion enclosing therein a micromotor or a turbine rotor and a forward end portion detachably attached to the body portion and having a tool at the fore end thereof. As occasions demand in treatment, various types of forward portions are alternatively attached to the common body portion of the handpiece. It is necessary in view of efficiency and safety in treatment that the forward end portion of the handpiece should remain firmly attached to the body portion and not fall off inadvertently therefrom while in use for treatment.

In one known type of handpiece, the forward end portion is connected to the body portion by frictional contact. However, such a way of connection cannot ensure 100 % firmness in connection. To improve the firmness in connection, a screw may be used to clamp the forward portion of the dental instrument to the body portion thereof. With this arrangement, however, two actions are required to connect the two portions, that is, first the forward end portion is inserted to the body portion and then the screw must be put in place, so that speedy operation cannot be expected.

It is one object of the invention to provide a dental handpiece wherein firm and secure connection between the foward end and body portions of the handpiece can be easily effected by a single action of inserting the former into the latter portions and subsequent relative rotation of the two portions.

The invention will be described in detail with reference to the accompanying drawings, wherein:

FIG. 1 is a perspective view of the handpiece of the invention, with the forward end portion thereof being disconnected from the body portion thereof;

FIG. 2 is an enlarged perspective view in longitudinal section, of the forward end of the body portion;

FIGS. 3a, 3b and 3c are schematic views illustrating the operation of the connecting mechanism of the invention.

Referring to the drawings, there is shown in FIG. 1 a dental handpiece comprising a body portion 1 and a forward end portion 2 detachably attached to the body portion in the manner to be described later in detail. The body portion 1 encloses a micromotor, not shown, which rotates a tool 3 detachably attached to the tip of the forward end portion 2 when the two portions 1 and 2 are connected. The power transmission between the motor and the tool is so well-known that it is neither shown nor requires further explanation.

The body portion 1 is provided at its forward end with an axial bore 11 adapted to receive the rear end of the forward end portion 2 of the handpiece in the manner to be described later. The bore 11 is provided in its inner surface with an axial slot 12 which a slide key 13 engages. The key is rigidly connected by means of a pin 15 to a slide member 14 provided on the outer surface of the body portion 1. By sliding the member 14 from outside the handpiece it is possible to move the key 13 along the slot 12 inside the instrument body 1.

A spring 16 normally urges the member 14 and consequently the key 13 toward the forward end of the body 1. The slot 12 is provided at a predetermined longitudinal position thereof with a lateral recess or notch 17 extending in the circumferential direction of the bore 11. The recess 17 is normally closed by the spring-urged key 13 as shown in FIG. 3a.

The forward end portion 2 of the handpiece has a connecting shaft 21 adapted to be inserted into the bore 11 of the body portion 1 for connection of the two portions 1 and 2. The shaft 21 has an outer diameter a little smaller than the inner diameter of the bore 11, so that the shaft can be rotated inside the bore 11. The shaft 21 is provided on the outer surface thereof with a small engaging pin 22 having a diameter a little smaller than the width of the slot 12 and the recess 17, so that the pin 22 can freely move in the slot 12 and the recess 17. The length of the recess 17 in the circumferential direction of the bore 11 is much the same as the diameter of the pin 22.

Without the forward end portion 2 in the bore 11, the slide key 13 is urged forwardly by the spring 16 to close the recess 17 as previously mentioned with reference to FIG. 3a. When the forward end portion 2 is to be connected to the body portion 1, the shaft 21 of the former portion 2 is inserted into the bore 11 of the latter portion 1, with the pin 22 engaging in the slot 12. As the shaft 21 is moved inwardly, the pin 22 hits against the slide key 13 in the slot 12 and pushes the key 13 against the resiliency of the spring 16 further inwardly in the slot as far as the key 13 is stopped by the inner end of the slot 12, where the key 13 opens the recess 17 as shown in FIG. 3b. The length of the slide key 13 is the same as the distance between the inner end of the slot 12 and the inner side edge of the recess 17. Under the condition that the key 13 opens the recess, the forward end portion 2 of the handpiece and consequently the shaft 21 is turned in the direction as indicated by arrows in FIG. 3b, so that the pin 22 engages in the recess 17, whereupon the pin 22 no longer exists in the slot 12 so that the key 13 is pushed by the spring 16 back to the original position as shown in FIG. 3c. Now the portions 1 and 2 of the handpiece have been connected, and with the slide key 13 confining the pin 22 within the recess 17, no axial pulling or rotation of the forward end portion 2 relative to the body 1 is allowed, so that the two portions 1 and 2 are securely connected.

In order to disconnect the foward end portion 2 from the body portion 1, the slide member 14 is simply moved toward the rear end of the body against the force of the spring 16 so as to remove the key 13 from in front of the recess 17 and then the forward end portion 2 is simply turned to disengage the pin 22 from the recess 17 and then axially pulled out of the body portion 1.

Thus, in accordance with the invention, a simple action suffices to connect the two portions of the handpiece, that is, to simply insert the forward end portion into the body portion and turn the two portions relative to each other. Under the connected condition, unless the slide member 14 is moved, the two portions are never separated, and in view of the position of the slide member 14 there is no likelihood that the dentist handling the handpiece inadvertently touches the slide member 14 to effect separation of the two portions. Disconnection of the two portions when necessary can be effected as simply and easily as the connecting operation .

Claims

What I claim is:

1. A dental handpiece comprising: a body portion and a forward end portion detachably connected to said body portion; said body portion being provided with an axial bore which opens at the forward end of said body portion, an axial slot formed in the inner surface of said bore, a lateral recess formed in said slot and a slide key in said slot normally urged to a position to close said recess, said slide key being normally urged by a spring to said recess closing position and being movable out of said position against the force of spring to a recess opening position; and said forward end portion having means for supporting a rotary dental tool and a shaft removably inserted into said axial bore of said body portion and being provided with a pin slidably engageable in said slot in said axial bore when said shaft is inserted into said axial bore so that said pin pushes said key out of said recess closing position and, upon relative rotation of said forward end portion to said body portion, engages in said recess, whereupon said key is restored to said original recess closing position and said pin and thereby said forward end portion are securely connected with said body portion so as to prevent relative axial and rotative movement therebetween.

2. The handpiece of claim 1, further including a slide member provided on the outside of said body portion and connected to said slide key, so that when said slide member is moved, said slide key is moved out of said recess closing position.

3. The handpiece of claim 1, wherein said axial bore of said body portion functions as a bearing for said shaft of said forward end portion.

4. A dental handpiece, comprising: a body portion having an axially centered bore at the forward end thereof; detachable dental tool supporting means including rearwardly extending shaft means on the rear end thereof insertable into the axial bore, and means for receiving a dental tool on the forward end thereof; transverse extension means projecting transversely outwardly from the side of the shaft means; means defining a slot extending lengthwise along the interior of the axial bore; means defining a notch in communication with the slot, the transverse extension means being guided by the slot into the notch during insertion of the shaft means into the axial bore; and means for preventing escape of the transverse extension means from the notch once the shaft means are inserted into the axial bore so as to restrain the dental tool supporting means against rotative and axial movement relative to the body portion, wherein the escape prevention means includes a reciprocative member mounted for sliding movement along the lengthwise slot between a locking position blocking passage of the transverse extension means between the lengthwise slot and the notch and a release position permitting passage of the transverse extension means between the lengthwise slot and the notch.

5. The dental handpiece according to claim 4, wherein the slot extends axially along the interior of the axial bore.

6. The dental handpiece according to claim 4, wherein the lengthwise slot has a width representing the width of the shaft transverse extension means, and wherein the notch is disposed intermediate the ends of the lengthwise slot transversely to the length thereof, the depth and width of the notch representing, respectively, the length and width of the shaft transverse extension means.

7. The dental handpiece according to claim 6, wherein the notch extends depthwise circumferentially of the axial bore and widthwise longitudinally of the axial bore.

8. The dental handpiece according to claim 4 wherein the reciprocative member comprises a slide key mounted for sliding movement inside the lengthwise slot.

9. The dental handpiece according to claim 8, wherein the slide key is nestled conformably within the lengthwise slot to fair together the interior of the axial bore and the outer surface of the slide key, whereby unobstructed insertions of the shaft means into the axial bore is permitted.

10. The dental handpiece according to claim 8, wherein the lengthwise slot includes an extension portion to the rear of the notch, the slide key in the release position thereof being slidably mounted inside the rearward slot extension.

11. The dental handpiece according to claim 4, including means for displaceably positioning the escape prevention means for engagement with the transverse extension means, the escape prevention means being temporarily displaceable by the transverse extension means so as to permit entry of the transverse extension means from the lengthwise slot into the notch during insertion of the shaft means into the axial bore.

12. The dental handpiece according to claim 4, including an operator member slidably mounted on the outer surface of the body portion, and means for interconnecting the operator member with the reciprocative member whereby the reciprocative member is moved conjointly with the operator member.

13. The dental handpiece according to claim 12, including means for normally biasing the reciprocative member to the locking position.