1. Technical Field
The present invention relates to an angle measurement device, and more particularly, to an angle measurement device for measuring a blade angle of a dental instrument and an angle-measurement assist device therefor.
2. Related Art
In dental treatments, various types of bladed dental instruments are employed. Especially, scalers are widely employed for scaling tartar and dental plaque on the teeth and for root-planing periodontal faces of the teeth. A scaler has a handle grasped by an operator and a shank extending therefrom and having a distal end portion thereof formed with a bladed portion of a semi-cylindrical shape in cross section. The bladed portion has a flat upper face and a semi-cylindrical face that has flat opposite edge portions crossing the flat upper face to form two ridge lines which constitute two tips of the blade. To meet conditions for dental treatments which vary in dependence on types of dental treatments as well as shapes and parts of the teeth subject to dental treatments, a distal half of the shank is formed into a simple straight-line shape, a complicated shape curved in three dimensions, or the like.
In order to efficiently carry out dental treatments such as scaling and root planing to enhance therapeutic effects, it is important to maintain the sharpness of a scaler. When a scaler is in use, however, the sharpness of the scaler blade is liable to be deteriorated. Thus, the sharpness of the scaler blade is checked before and during the use of the scaler, and the scaler is sharpened manually or with the use of an electric sharpening apparatus, as required, to maintain a desired sharpness.
A typical electric sharpening apparatus, having a sharpening stone rotated by an electric motor and adapted to be pressed against the scaler, can excessively sharpen the scaler blade and cannot achieve easy sharpening during the dental treatment. On the contrary, manual sharpening can be carried out with ease during the dental treatment by sliding a sharpening stone along a scaler. However, manual sharpening requires skills since the scaler blade is extremely small having about a 2.0 mm length and about a 0.5 mm thickness at the minimum and the scaler may have a complicated shape as mentioned above. Thus, it is difficult for an unskilled operator to uniformly and smoothly sharpen the entirety of the scaler blade.
In this respect, the present inventors proposed a manually-operated sharpening apparatus as disclosed in Japanese provisional patent publication no. 2000-24889, which permits easy sharpening of a bladed dental instrument. However, difficulties are encountered in making a visual inspection to promptly and accurately determine whether a dental instrument is sharpened to have a proper blade angle.
An object of the present invention is to provide an angle-measurement assist device for assisting a visual angle measurement with respect to a measurement object having a portion made of a magnetic material.
Another object of the present invention is to provide an angle measurement device for promptly and easily carrying out an angle measurement with accuracy with respect to such a measurement object.
Still another object of the present invention is to provide a manually-operated sharpening apparatus provided with an angle measurement device of the just-mentioned type.
According to one aspect of the present invention, there is provided an angle-measurement assist device which comprises: a holder having a first flat face thereof adapted to be in contact with a measurement object portion of a measurement object, the measurement object portion being subject to an angle measurement and made of a magnetic material; a permanent magnet mounted to said holder for permitting said device to be magnetically retained on the measurement object portion; and a straight member projecting from a second face of said holder and having a size sufficiently greater than that of the measurement object portion.
According to the angle-measurement assist device of this invention, when the holder mounted with the permanent magnet is in contact at its first flat face with a measurement object portion made of a magnetic material, the assist device is magnetically retained on the measurement object portion and the first flat face of the holder extends in substantially the same direction as an extending direction of the measurement object portion. Since the straight member has a size sufficiently greater than that of the measurement object portion and extends at a known angle relative to the first face of the holder, an operator is enabled to make a visual inspection to determine an angle of the measurement object portion, which angle is indicated under magnification by the extending direction of the straight member.
In the present invention, preferably, said straight member extends in parallel with the first flat face of said holder. According to this preferred embodiment, the straight member of the assist device retained on the measurement object portion extends substantially the same direction as an extending direction of the measurement object portion, so that an operator is permitted to make a visual measurement on the angle of the measurement object portion based on the extending direction of the straight member.
More preferably, the measurement object is a dental scaler having a handle adapted to be grasped by an operator and a shank extending therefrom and having a distal end portion thereof formed with a bladed portion which constitutes the measurement object portion. With this preferred embodiment, a visual measurement on the blade angle of the scaler can be made based on the extending direction of the straight member of the assist device retained on the bladed portion of the scaler.
According to another aspect of the present invention, there is provided an angle measurement device which comprises an angle-measurement assist device and a scale plate. The assist device comprises: a holder having a first flat face adapted to be in contact with a measurement object portion of a measurement object, the measurement object portion being subject to an angle measurement, made of a magnetic material, and provide in a distal end portion of a shank of the measurement object which extends from the main body of the shank at a shank angle; a permanent magnet mounted to said holder for permitting said assist device to be magnetically retained on the measurement object portion; and a straight member projecting from a second face of said holder and sufficiently greater in size than the measurement object portion. The scale plate has a central portion thereof formed with a hole permitting the distal end portion of the shank to pass therethrough and is provided with a first scale indicative of a target positioning angle for the main body of the shank and a second scale indicative of a target angle of the measurement object portion which is to be established when the main body of the shank is positioned at the first scale.
Preferably, the angle measurement device further includes a base plate for supporting the scale plate in a state that the scale plate vertically extends from the base plate.
According to the angle measurement device of this invention, an operator is enabled to easily and accurately determine whether the angle of the measurement object portion such as a blade angle coincides with a target angle on the basis of an extending direction, relative to the second scale, of the straight member of the assist device retained on the measurement object portion, with the main body of the shank of the measurement object positioned at the target angle indicated by the first scale and the distal end portion of the shank passing through the hole of the scale plate.
According to still another aspect of the present invention, there is provided an angle measurement device which comprises an angle-measurement assist device and a base plate. The angle-measurement assist device comprises: a holder having a first flat face thereof adapted to be in contact with a measurement object portion of a measurement object, the measurement object portion being subject to an angle measurement, made of a magnetic material, and provided in a distal end portion of a shank of the measurement object which extends from a main body of the shank at a shank angle; a permanent magnet mounted to said holder for permitting said angle-measurement assist device to be magnetically retained on the measurement object portion; and a straight member projecting from a second face of said holder and having a size sufficiently greater than that of the measurement object portion. The base plate is provided with a first scale indicative of a target positioning angle for the main body of the shank and a second scale indicative of a target angle of the measurement object portion which is to be established when the main body of the shank is positioned at the first scale.
Preferably, first and second lines serving as the first and second scales are drawn on the base plate. Alternatively, the angle measurement device includes a scale plate provided with the first and second scales and adapted to be disposed on the base plate.
According to the angle measurement device of this invention, an operator is enabled to determine whether the angle of the measurement object portion coincides with a target angle on the basis of an extending direction of the straight member of the assist device retained on the measurement object portion, with the main body of the shank of the measurement object positioned at the first scale.
Alternatively, the base plate is provided with angle graduations instead of the second scale. With such an angle measurement device, a visual measurement on the angle of the measurement object portion can be made by comparing the angle graduations with an extending direction of the straight member of the assist device retained on the measurement object positioned at the first scale.
In the angle measurement device of this type, preferably, a rod member is disposed on the base plate so as to be pivotable around one end of the rod member. More preferably, an arcuate member is fixed on the base plate, and another end of the rod member moves along the arcuate member as the rod member is pivoted. With this preferred embodiment, a visual measurement on the angle of the measurement object portion can be made by pivoting the rod member to coincide with an extending direction of the straight member of the assist device retained on the measurement object positioned at the first scale and then comparing the angle graduations with the extending direction of the rod member which indicates the extending direction of the straight member.
According to still another aspect of the present invention, there is provided a manually-operated sharpening apparatus which comprises a sharpening section, an angle-measurement assist device, and a scale plate. The sharpening section includes a base plate having a substantially flat face; a sharpening member for sharpening a workpiece portion of a workpiece, the workpiece portion to be sharpened being made of a magnetic material and provided in a distal end portion of a shank of the workpiece extending from a main body of the shank at a shank angle; a guide member, fixed on the substantially flat face of the base plate, for guiding the sharpening member attached thereto so as to permit the sharpening member to move therealong; a positioning-assist element including a positioning line drawn on the substantially flat face of the base plate and extending at a predetermined angle with respect to the guide member, for permitting an operator to orient the workpiece in a state where the predetermined angle is formed between the workpiece portion and the sharpening member. The angle-measurement assist device includes: a holder having a first flat face thereof adapted to be in contact with the workpiece portion to be subject to an angle measurement; a permanent magnet mounted to said holder for permitting said angle-measurement assist device to be magnetically retained on the workpiece portion; and a straight member projecting from a second face of said holder and having a size sufficiently greater than that of the workpiece portion. The scale plate has a central portion thereof formed with a hole permitting the distal end portion of the shank to pass therethrough, and is provided with a first scale indicative of a target positioning angle for the main body of the shank and a second scale indicative of a target angle of the measurement object portion which is to be established when the main body of the shank is positioned at the first scale.
According to the manually-operated sharpening apparatus, an operator is enabled to manually sharpen a workpiece portion such as a bladed portion of a scaler to have a proper angle by simply moving the sharpening member along the guide member in a state that the sharpening member attached to the guide member is abutted against a workpiece properly positioned with use of the positioning-assist element. Before and in the course of a sharpening operation, the operator is enabled to determine whether the angle of the workpiece portion coincides with a target angle on the basis of an extending direction of the straight member, relative to the second scale, of the assist device retained on the workpiece portion, with the shank of the workpiece positioned at the first scale. Furthermore, the assist device can be accurately retained on the workpiece portion sharpened flat by use of the sharpening member. In other words, the sharpening section cooperates with the assist device to achieve a synergistic effect of improving the assist-device retaining accuracy, i.e., the measurement accuracy.
According to still another aspect of the present invention, there is provided a manually-operated sharpening apparatus which comprises a sharpening section and an angle-measurement assist device. The sharpening section includes a base plate having a substantially flat face; a sharpening member for sharpening a workpiece portion of a workpiece, the workpiece portion to be sharpened being made of a magnetic material and provided in a distal end portion of a shank of the workpiece extending from a main body of the shank at a shank angle; a guide member, fixed on the substantially flat face of the base plate, for guiding the sharpening member attached thereto so as to permit the sharpening member to move therealong; a positioning-assist element including a positioning line drawn on the substantially flat face of the base plate and extending at a predetermined angle with respect to the guide member, for permitting an operator to orient the workpiece in a state where the predetermined angle is formed between the workpiece portion and the sharpening member. The angle-measurement assist device includes: a holder having a first flat face thereof adapted to be in contact with the workpiece portion to be subject to an angle measurement; a permanent magnet mounted to said holder for permitting said angle-measurement assist device to be magnetically retained on the workpiece portion; and a straight member projecting from a second face of said holder and having a size sufficiently greater than that of the workpiece portion.
According to the manually-operated sharpening apparatus, an operator is enabled to sharpen the workpiece portion to have a target angle by moving the sharpening member along the guide member and enabled to determine whether the angle of the workpiece portion coincides with the target angle based on an extending direction of the straight member of the assist device retained on the workpiece portion. Further, the angle-measurement assist device can be accurately retained on the workpiece portion sharpened flat to improve the measurement accuracy.
Preferably, the guide member is formed on the flat face of the base plate integrally therewith. Alternatively, the guide member is disposed on the flat face of the base plate so as to be pivotable around one end of the guide member, and is adapted to be fixed at an arbitrary pivotal angular position. More preferably, the guide section includes an arcuate member fixed to the flat face of the base plate. As the guide member is pivoted, another end of the guide member moves along the arcuate member.
According to the latter embodiment having the pivotable guide member, a manually-operated sharpening apparatus is provided, which is suitable for the sharpening and angle measurement of various workpieces having different shank shapes from one another. By using the guide member in the same manner as the rod member in the aforementioned angle measurement device, a visual measurement on the angle of the workpiece portion can be made.