Photography – Plural image recording – Stereoscopic
Reexamination Certificate
1997-10-30
2001-03-27
Gray, David M. (Department: 2851)
Photography
Plural image recording
Stereoscopic
C396S331000
Reexamination Certificate
active
06208813
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method for taking pictures of the human body, especially of the mouth cavity, or of a model for artificial construction of a tooth, dentine, a pros thesis, etc., here called “objects”, and for taking these pictures from at least two different angles. So-called stereophotography, that is photography for three-dimensional measurement, etc. may be appropriate in this respect. The method uses camera equipment which comprises a camera housing for film or other image-recording material, a lens system, which, when photographs are being taken, is aimed at one or more objects or object parts, for example an implant, tooth remnant, tooth, etc. Possible examples of image-recording material besides film (silver film) are digital video (CCD camera) or digital camera. The invention also relates to a camera for implementing the method.
BACKGROUND OF THE INVENTION
It is already known to use stereophotography in connection with producing dental articles and for dental work, in which case at least two cameras have generally been set up at a distance from one another and have been activated for taking pictures from different angles. It is also already known to use stereophotography in photogrammetric connections for measuring locations and positions of various surfaces, teeth, objects, etc. In order to be able to reach conclusions on the actual positions in space/the actual coordinate system, it is possible to use various aids, such as coordinate-measuring equipment, marked glass discs, etc.
There is a requirement facilitate the production of dental articles (dental bridges, e.g. dental caps, etc.) in a simpler way compared with present-day production methods. The invention is directed to solving this problem.
When producing dental bridges, prostheses and the like, a model is normally made at present by taking an impression with an impression compound in the mouth cavity. An object of the invention is to eliminate such modelling in the production of such dental articles.
The use of stereophotography is not entirely self-evident in this context, even if it does solve the problem of eliminating modelling with an impression compound. The use of two or more cameras for establishing stereophotographs presents problems, since it is difficult to prevent the patient from moving between two exposures. Even very small time delays between exposures and small movements of the patient, have a deleterious effect on the result. As a result, persons skilled in the art have heretofore concluded that the use of multiple cameras is not suited to everyday clinical use. The invention solves this problem and makes it possible for the present invention to be used in a practical application involving a patient.
Stereophotography must be able to provide a greater degree of accuracy or resolution in the dental product compared with previous uses of stereophotographic equipment. The invention solves this problem and also displays a greater degree of accuracy even in comparison with the use of the above mentioned modelling.
It has been shown that methods and arrangements used hitherto have led to static stress forces being built into the dental article/dental bridge in question. Even though these forces are relatively small, they lead in the long term to a collapse of all or part of the jaw bone in question. There is therefore a need for substantially greater accuracy of production than has previously been the case. The invention solves this problem too.
In connection with dental work in and around the mouth cavity, it is important that the photographic equipment employed have small dimensions and be easy to handle when in use. The space available in and around the patient's mouth cavity is limited, and the personnel providing the treatment should not need to possess any photographic expertise in order to perform their dental work. The invention solves this problem as well.
In accordance with the concept of the invention, the mirrors reflecting the optical radiation are used to form virtual lens functions which are arranged at a distance from one another to obtain a stereo imaging effect. In one embodiment, the interaction between the camera parts and the reflection surface(s) are locked in a mutual relationship at the site so that simplified use of the camera is achieved. The invention solves this problem too.
In a further embodiment, it is possible for the measurements in the images to be overdefined and for the positions of the lenses to be determined by means of solution of equation systems. This is also permitted by the invention.
There is a need to render more efficient all the operations surrounding the production of dental articles which are applied in the mouth cavity, with the whole production chain being taken into account, including examination of the patient's mouth and production in the actual material (titanium, for example) in the machine. The novel method and arrangement of the invention reveal new avenues for realizing such methods and arrangements and can be used, in connection with methods and the arrangements known in the art.
When working in the mouth cavity, it should be possible, for example, to effect imaging of a number of implants (2 to 6 implants, for example) in a jaw bone both at the level of the fixture and at the level of the spacer. The invention solves this problem.
SUMMARY THE INVENTION
The feature which can principally be regarded as characterizing a method according to the invention is that optical radiation emanating from a respective object or object part is reflected on one or more radiation-reflecting reflection surfaces, which are situated between the respective object or object part and the lens system, before passing through the lens system to the film in the camera housing to obtain at least two lens functions which are situated at a distance from one another and of which at least one is virtual. Two or more different images of the respective object or object part are generated with the lens functions from the different angles at one and the same exposure.
In a preferred embodiment, the optical radiation from the respective object or object part is made to pass an end surface on a unit which is provided with one or more inner walls, each forming a reflection surface.
The feature which can principally be regarded as characterizing a camera according to the invention is that it is arranged with one or more reflection surfaces situated between the lens system and the respective. object/object part or tooth/tooth replacement, and that the reflection surface(s) reflect optical radiation emanating from the respective object or tooth/tooth replacement, or part thereof, before the optical radiation passes through the lens system and reaches the film or equivalent. Further characteristics are that the one or more reflection surfaces arranged to establish at least two lens functions which are situated at a distance from one another, of which at least one lens function is virtual. The lens functions produce, on film, images from different angles at one and the same exposure.
In a further embodiment, the reflection surfaces are two in number, and the reflection surfaces extend essentially parallel to the viewing direction of the camera. In this way, three images of the respective object or tooth/tooth replacement, or part thereof, are obtained on the film during the same exposure. This is achieved because the two virtual lens functions occur together with the lens function performed by the lens system.
In one embodiment, the camera comprises a standard camera provided with a flash function, for example a 35-mm miniature camera with, for example, a 24-mm wide-angle lens. This basic construction is known per se and is a in this case, provided with the reflection surface(s) or mirror surface(s). The real or actual lens is preferably arranged in a fixed manner on the camera housing, for example by means of glue, to obtain optical and geometric stability. Members, for example a glass disc, can be arranged to ensure that the film is ap
Carlsson Lennart
Jemt Torsten
Lie Anders
Connolly Bove Lodge & Hutz
Gray David M.
Nobelpharma AB
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