Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
1998-05-29
2001-04-03
Grant, William (Department: 2786)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S161000
Reexamination Certificate
active
06212442
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a device for compressing the quantity of information which is obtained in an apparatus for sensing or reading even the complex shape of a model of a dental product or other product related to the human body, or body part, or tool for producing the product or the body part. The compressed quantity of digital information is included in, or forms, control information, which can be transferred by way of a remote link and/or data link, for machining equipment which is arranged in or at premises which are separate from the locality for the sensing or reading. With the aid of the control information, the machining equipment produces, from a blank, the said product, a replacement part for the said body part, or the tool.
STATE OF THE ART
It is previously known, in connection with producing dental products, to carry out a sensing function in both the cartesian and the polar coordinate systems. In this context, it is known that the sensing in, for example, the cartesian coordinate system normally results in large quantities of information.
It is also previously known to utilize the same profiles on a mechanical sensing needle and a tool in the machining equipment in question, which contributes to reducing the quantity of information. As far as the quantity of information which has to be transferred from a sensing unit to a machining unit is concerned, this approach is advantageous when, in the sensing and the machining functions, the model and the sensing needle, and the blank and the tool, respectively, are also rotated and displaced longitudinally in a reciprocal manner and when the same inclinations (45°) between the model and the sensing needle, and the blank and the tool, respectively, are retained.
It is also known that non-mechanical sensing principles, for example optical sensing principles, increase the quantity of information.
It is also previously known to transfer the sensed information from a sensing unit to the machining unit, for the purpose of achieving control information for the latter, on a telecommunication link, for example an established link in the public telecommunication network.
Reference is also made to EP 541500 A1.
ACCOUNT OF THE INVENTION
TECHNICAL PROBLEM
In some cases, there is a need to be able to carry out reading or sensing functions using systems and equipment which yield a relatively large quantity of read-off or sensed information, which quantity can only be handled inefficiently in association with transferring it via the remote and/or data link. In these cases, it is a matter of importance that it should be possible to compress the quantity of information before the transmission to the machining unit takes place without essential machining information being lost for that reason. In this context, it can be noted that the demands on manufacturing precision are high (for example 0.02 mm) in the case of dental products and compressions cannot be permitted which distort the reading. The compression must be carried out in such a way that the characteristics, and complex, individual shape, of the model or equivalent are transferred to the product, tool, etc., which is produced. In addition, quantities of information which give rise to long transfer times on the link are unacceptable. It is only possible to permit transfer times on the link of at most a few minutes. Consequently, there is a need to compress the reading substantially in the case of reading systems which yield large quantities of information. The invention is directed towards solving this problem.
There is a need to reduce the quantity of information, prior to transmission on the link, in the case of, for example, sensing a model, body part (tooth crown, tooth neck, oral cavity, etc.) or tool having complicated internal or external shapes and which is sensed in the cartesian coordinate system. The invention solves this problem as well.
There is also a need to employ non-mechanical principles using light (laser), sound, etc., when reading a model, for example.
An efficient machining function can be achieved by working in the polar coordinate system, where the blank is rotated and the blank and the tool are simultaneously displaced longitudinally in a reciprocal manner, with the inclination between the tool and the blank preferably being selected to be 45°. It should be possible to maintain the arrangement in question despite the reading taking place in a cartesian coordinate system. The invention solves this problem as well.
SOLUTION
A presently proposed device which solves the abovementioned problems can principally be regarded as being characterized in that the compression can be effected by means of the apparatus sensing or reading the model or the body part in a first (for example cartesian) coordinate system for the purpose of extracting first coordinates which can be assigned to this system. In this context, first means are organized for converting the first coordinates which have been obtained in this way to corresponding second coordinates which describe the shape in a second, or polar, coordinate system. The second coordinates form or constitute the basis for the control information.
The new device can also be regarded as being characterized in that second means are supplied information which corresponds to, and is essentially proportional to, a size of a surface by which a tool, for example in the form of a milling cutter, which is included in the machining equipment interacts with the blank when the latter is being machined. In this context, it is characteristic that the said surface size is at least {fraction (1/10)}-{fraction (1/100)} of the surface of the model, body part or tool. Using the said supplied information, the second means reduce the sensing or reading information in dependence on the surface size such that there is a more extensive reduction in the case of a larger surface size, and vice versa.
The new device can also be regarded as being characterized in that the apparatus senses the model or the body part in a first (polar) or second (cartesian) coordinate system in accordance with a non-mechanical (i.e. optical, sound-related, etc.) sensing or reading principle. In this context, third means are arranged to convert the non-mechanical sensing or reading function to a mechanical sensing function which operates with a sensing element which interacts with the shape of the model/replacement part/tool. In this context, the profile of the sensing element which interacts with the shape, and the inclination of the sensing element in relation to the shape, correspond to the profile of a tool part which interacts with the blank or, respectively, the inclination of the tool in relation to the blank.
In one embodiment of the invention concept, the said first or second means include a computer which can be used to simulate both the sensed or read-off shape of the model or body part and a profile which corresponds to the profile of the part of the machining tool which can interact with the blank. In a further embodiment, the first means activate the computer to simulate rotation, around a central axis, of the sensed or read-off model, body part or tool. In a supplementary, or alternative, manner, the computer simulates a sensing function, effected in the polar coordinate system, relative to the surface presentation of the model, body part or tool by means of a profile which bears against the shape or surface of the model, body part or tool and which corresponds to the profile of the tool of the machining equipment. In this context, the first means read the second coordinates, in a manner known per se, using the sensing and reading function and the simulated reciprocal movements of the model/body part/tool in order to obtain the control information.
In a further embodiment, the second means activate the computer to simulate, in a cartesian coordinate system, the movements of the sensing function in relation to the read-off or sensed surface of the simulated model/body part/tool in different sensing positions and to indicate respec
Andersson Matts
Persson Magnus
Grant William
Nobel Biocare AB
Pollock, Vande Sande & Amernick, R.L.L.P.
Rapp Chad
LandOfFree
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