Source: https://patents.justia.com/patent/5131844
Timestamp: 2019-10-21 07:18:00
Document Index: 763964515

Matched Legal Cases: ['art 117', 'art 117', 'arts 117', 'art 127', 'art 185', 'art 127', 'art 127']

US Patent for Contact digitizer, particularly for dental applications Patent (Patent # 5,131,844 issued July 21, 1992) - Justia Patents Search
Justia Patents Having Gauge Or GuideUS Patent for Contact digitizer, particularly for dental applications Patent (Patent # 5,131,844)
Contact digitizer, particularly for dental applications
Apr 8, 1991 - Foster-Miller, Inc.
Magnet robot crawler
1,230,156      1,387,329    1,799,528
1,831,390      2,119,823    2,119,824
2,299,151      2,447,287    2,566,903
2,701,915      2,841,871    3,035,348
3,063,149      3,152,401    3,218,624
3,226,828      3,254,413    3,380,163
3,490,146      3,564,717    3,777,740
3,943,913      3,943,914    4,085,514
4,344,755      4,390,028    4,402,326
4,445,857      4,495,952    4,634,377
4,639,220
According to another feature, the invention provides a dental surface tracer including a dental probe having six degrees of freedom, comprising: a mounting device which is capable of being mounted to a reference location with respect to a given jaw and defining a base plane; a first link which is integral with said mounting device; substantially coplanar second, third and fourth links defining a plane of movement; said second link being pivotally mounted to said first link so that said plane of movement is movable above and below said base plane; first means for generating electrical signals representative of such movement; said second, third and fourth links being jointed together to have predetermined ranges of relative angular motion so that a distal end of said fourth link is movable over a predetermined area in said plane of movement; whereby said distal end has three degrees of freedom; second means for generating electrical signals representative of such movement; a probe; and gimbal means supporting said probe and attached to said distal end of said fourth link, for permitting said probe to move with three degrees of freedom without any movement of said first through fourth links; whereby said probe can move with respect to said reference location with six degrees of freedom. All of said links and gimbal means are sized for being accommodated within the human mouth. The second, third and fourth links are jointed to provide greater than 90.degree. of relative angular motion between each pair of adjacent links, or more advantageously, substantially 100.degree. of relative angular motion.
The digitizer was designed with the practical needs of the dental practitioner or dental lab in mind. For example, for crown restorations, after tooth preparation (without gingival retraction procedures), the device is temporarily attached to a sound tooth which acts as a jaw-based reference point. The tip of the probe is wiped over the surface of the teeth to be digitized. It will take less than about 3 minutes to digitize a single tooth for crown restorations and less than 15 sec/tooth, or about 8 min. (32 tooth.times.0.25 min/tooth) for orthodontic applications, the data being recorded at a rate of several hundred points per second. A minimum of about 400 surface points per tooth is believed necessary for an accuracy of under 25 microns. Direct contact with the surface avoids the problems of translucence and moisture-caused reflection. The ability to fully articulate a very small ball tip (no more than about 0.5 mm) solves the parallax problem by reaching all parts of the tooth, including below the gum line.
FIG. 4 is a view showing the pivot block 2 mounted on the base 1. See also FIGS. 2 and 5. The pivot block 2 is force-fitted onto the stem 103 of the base 1, via a central bore 107, which is tapered to match the taper of the stem 103. The angle of taper is very small, for example about 3.degree., and provides a "locking taper." The frame 7 is pivotable about the pivot block 2 in the plane of the drawing as shown in FIG. 2.
In the frame 7, the bearings 5 receive a pair of tapered projections 110 on an outer surface of the pivot block 2 Thus, the frame 7 is pivotable with respect to the pivot block 2. As shown in FIG. 2 in phantom, advantageously the available pivot angle is at least 15.degree. above and below the horizontal, as defined by the cross piece 101 of the base 1. Note in FIG. 2 that the frame 7, the straight link 8 and the dogleg link 9 are joined so as to pivot together as a unit through the entire 30.degree. range of motion with respect to the pivot block 2.
Substantially a 40.degree. angle is formed between the cutout surface 113 and the lengthwise inner surface 112a of the aperture 112. Substantially a 50.degree. angle is formed between the surface 112a and an extension 113a of the surface 113, which is offset substantially 10.degree. from the surface 113. The lengthwise surface 115 is offset substantially 10.degree.30' from the surface 112a. The bearings 5 shown schematically in FIG. 6 are held in the frame 7 by adhesive. As shown in FIG. 6A, a side view of the frame 7, the second end 117 in which the bearing hole 114 is formed, comprises an upper part 117a (with a hole 114a) and a lower part 117b (with a hole 114b) which are parallel and form a fork. As shown schematically in FIG. 6A, bearings 5, preferably ball-bearings, are respectively secured in the upper and lower parts 117a, 117b by adhesive.
The link 8 is substantially constant in width (0.1875 inch), as seen in FIG. 7A. The first end 123 has a substantially circular rounded outline. The second end 124 is substantially circularly rounded on one lateral side, but has a flattened part 127 which in this example forms substantially an 80.degree. angle with the adjacent lateral side. The second end 124 also has a bore 128 which receives a suitable shaft which will be discussed below.
Extending from side to side of the link 8, substantially midway between its top and bottom surfaces, is an oblique bore 129. It is substantially circular in cross-section in this example and its cylindrical walls form substantially a 64.degree. angle with the lateral sides of the link 8.
The dogleg link 9 has a pair of lateral walls 143, 144 which define a longitudinal direction. The first end 140 has a first outer wall 145 which extends at substantially a 30.degree. angle to the longitudinal direction. A second outer wall 146 extends at substantially a 50.degree. angle to the longitudinal direction. An inner wall 147 extends at substantially a 50.degree. angle to the longitudinal direction. An end wall 148 forms a substantially 50.degree. angle to the longitudinal direction and forms a 100.degree. angle with both the second outer wall 146 and the inner wall 147.
A second inner wall 149 extends at substantially a 40.degree. angle to the longitudinal direction and accordingly, a 90.degree. angle to the first inner wall 147. It extends inward from the lateral wall 144. The surfaces of the second outer wall 146 and the end wall 148 are substantially flat and form a corner. The first end 140 is rounded between the end wall 148 and the first inner wall 147, preferably circularly
A cutout 155 extends from the top surface. At its lateral walls the cutout is defined by a pair of shoulders 156. The bottom wall within the cutout 155 is formed with substantially flat portions 157 adjacent the shoulders 156 and a central rounded portion 158. Preferably the flat portions 155 form substantially a 45.degree. angle with the horizontal. The rounded portion 158 is preferably cylindrical having an axis extending in the longitudinal direction of the link 9.
A side view, an end view, and a top view of the first arch 12 are shown in FIGS. 9, 9A and 9B, respectively. The first arch 12 has a first end 164 and a second end 165. The first end 164 has a rounded surface 166, preferably cylindrical, which is configured to match the rounded portion 158 in the cutout 155 of the dogleg link 9. A bore 167 receives a pin which engages the bearings 5 on either side of the cutout 155. The pin (not shown) is secured to the first end 164 by set screws provided in a pair of suitable bores 11. Extending upward from the first end 166 the arch 12 curves by 90.degree. and reaches the second end 165. The second end 165 has an upper portion and a lower portion which are parallel and have respective holes 172a and 172b which together define a bore 172. The holes 172a and 172b have respective bearings 5. A pair of angle walls 173a, 173b are formed in the arch 12 and define a space within the fork 165a, 165b at the end thereof away from the second end 165. The angle walls each form substantially a 45.degree. angle to the longitudinal sides of the arch 12 and thereby form a substantially 90.degree. angle to each other. Advantageously, the junction between the two angle walls may be broken to form a short flat portion 174 which is perpendicular to the longitudinal direction of the arch 12. The arch 12 measures substantially 0.666 inch horizontally from the end 164 to the center of hole 172.
The second arch 13 is shown in side view in FIG. 10 and a top view is shown in FIG. 10A. Starting from a first end 180 the second arch curves through 90.degree. and ends with a second end 181. A tongue portion 182 has a vertical bore 183 therein. With the tongue portion 182 inserted into the aperture 175 of the first arch 12, a pin 16 (FIG. 2) can be secured within the bore 193 by a set screw at 11 and rotatably supported in the bearings 5 of the second end 165 of the first arch 12.
Two pairs of angle walls 184a, 184b, 184c, 184d are formed at the end of the tongue portion 182 away from the first end 180. The angle walls 184a, 184b are above the tongue portion 182 and the angle walls 184c (not shown) and 184d are below the tongue portion 182. Preferably a small flat part 185 is formed at the junction between each pair of angle walls. A 90.degree. angle is formed between each pair of angle walls and each angle wall forms a substantially 45.degree. angle to the longitudinal direction of the arch 13. The arch 13 measures substantially 1.245 inch horizontally from the second end 181 to the center of the bore 183.
The probe 14 is substantially straight over about 2/3 of its length. It is threaded at a first end 192 The second end 193 is generally C-shaped. At its second end it has a probe tip 194 which is advantageously a ball having a diameter of about 0.5 mm. The contact tip advantageously is less than or equal to 0.5 mm in diameter, to minimize interference with gums and neighboring teeth. Advantageously, the curved second end 193 extends substantially perpendicularly at 193a to the shaft 192a, then at 193b runs parallel to the shaft, and then at 193c forms an angle of substantially 65.degree. to the shaft. The section 193c advantageously tapers to define an included angle of substantially 16.degree., so as to be smaller than the tip 194 at the point of attachment, but to increase rapidly in thickness so as to maintain the stiffness of the probe. The overall length of the probe 14 is substantially 1.70 inch.
The dogleg link 9, the straight link 8 and the frame 7 are configured for being joined by pins inserted through the bores 126, 128 in the link 8. When thus joined, as best seen in FIG. 1, the link 9 can be extended toward and away from the frame 7 while the frame 7 and the links 8 and 9 remain in the same plane. In other words, the frame 7 and the links 8 and 9 pivot as a unit through an angle of substantially 15.degree. above and below the horizontal, with respect to the pivot block 2.
The link 8 is shaped to fit compactly between the frame 7 and the link 9 when the latter are in their least extended position, as shown in FIG. 5. Note that in this position, the circularly rounded end 123 of the straight link 8 abuts the surface 113 of the frame 7 and in parallel therewith. Also in this position, the end wall 148 of the dogleg link 9 is angled so as to abut the 10.degree. offset extension 113a of the frame 7. On the other hand, the rounded part of the second end 124 of the link 8 abuts the frame 7, while the flattened part 127 of the second end 124 projects outward away from the frame 7.
FIG. 12 is a kinematic diagram showing the substantial range of motion obtainable by the arrangement of the frame 7, the link 8 and the link 9. In FIG. 12, alpha represents the rotation of the straight link 8 with respect to the frame 7, while beta represents the rotation of the dogleg link 9 with respect to the straight link 8. Reference numerals 126a, 126b and 126c show the position of the bore 126 when alpha equals 0.degree., 3.degree. and 100.degree., respectively. Reference numeral 128a indicates the position of the bore 128. A, B, C and D indicate the location of a distal end of the dogleg link 9 for various values of alpha and beta, which are shown in the drawing.
For example, starting from the least extended position shown in FIG. 5, the link 9 can be rotated throughout a wide angle beta of substantially 100.degree., which is limited by surface 148 on link 9 contacting surface 125a on the central portion 125 of link 8. As beta approaches 100.degree., an interference occurs between the end wall 148 and the extension 113a, whereby alpha is constrained to have a minimum value of 3.degree. when beta equals 100.degree.. A line 9' in FIG. 12 indicates a theoretical position the link 9 would take if alpha were 0.degree..
The value of alpha is limited to 100.degree. by the flattened part 127 on the second end 124 of the link 8, which comes into contact with a vertical side wall of the frame 7 when alpha reaches 100.degree..
As thus disclosed and described, the disclosed arrangement provides six degrees of freedom for the digitizer. The probe 14 is rotatable 360.degree. by its handpiece 20 about its axis, journalled within the first end of the second arch 13. While it is rotated, its probe tip remains at the axis of the pivot pin 16 between the first arch 12 and the second arch 13.
Because of the angle walls formed at a 45.degree. angle in each of the arches, each of the arches can pivot substantially 135.degree. out of the plane shown in FIG. 2. In other words, taking the position of FIG. 2 as a starting point, with the arch 12 held stationary, the arch 13 can be pivoted 135.degree. out of that plane in either direction. Throughout this pivoting motion, the probe tip 194 remains at the axis of the pivot pin 16 between the arches 12, 13 and at the axis of the bore 167 in the first end 164 of the arch 12.
The arch 12 is also pivotable about the pivot pin 15 within the cutout 155 in the dogleg link 9. Because of the flat portions 157 within the cutout 155, and the corresponding side surfaces of the first end of the arch 12, the arch 12 can pivot substantially 45.degree. in either direction about the pivot pin 15. Throughout the pivoting of the arch 12 within the cutout 155, the probe tip 194 remains concentric with the axis of the pivot pin 15.
The extension and pivoting motion of the link 9, the link 8 and the frame 7 has already been discussed. In addition, the frame 7 can pivot as shown in FIG. 2 substantially at least 15.degree. above and below the horizontal, about the bearings 5 of the pivot block 2. This linkage enables the probe tip to reach any portion of any tooth in the patient's mouth.
The substantially 100.degree. range of the angular motion of the second and third joints allows the Hall-effect sensors to detect this angular motion with great resolution. Because the digitizer links are very small, even a small movement of the probe tip results in a substantial angular movement of the joints. This combination of the small size of the links, and the resolution of the angular motion sensors, gives the probe great precision in the measurement of small distances.
An elongated NdFe magnet 10 is located in the bore 129 in the straight link 8 (FIG. 7a) and confronts respective Hall sensors 4b, 4c on the cutout surface 113 of the frame 7 and the second inner wall 149 of the link 9 (FIG. 5). By this arrangement of a single bar magnet between the two Hall sensors, plus the limitation on the values of the rotation angles alpha and beta, advantageously 100.degree., substantial interaction of the two sensing axes is avoided.
Referring now to FIG. 13, the Hall sensors S.sub.1, S.sub.2 and S.sub.3 are supplied with a constant reference current by a precision power supply 302 in an electronic assembly 300. S.sub.1 is the sensor closest to the third joint, while S.sub.3 is the sensor between the frame 7 and the pivot block 2. The signals from the Hall sensors are initially conditioned by corresponding low-noise amplifiers A.sub.1, A.sub.2, and A.sub.3 which amplify the sensor output voltages to the range of 1 to 10 V as required by further analog functional modules in this embodiment of the invention. The gain of the amplifiers is about 50. Then corresponding offset adjustment modules OS.sub.1, OS.sub.2, and OS.sub.3 remove the constant sensor bias voltage.
a linking arrangement supporting said probe and having a plurality of joints providing at least 6 degrees of freedom for the probe;
a device for attaching said linking arrangement to a stable reference location; and
a sensing system which measures all movements of said probe with respect to said reference location;
wherein said linking arrangement comprises a first plurality of joints providing three degrees of freedom for said probe, movement of those joints being sensed by said sensing system; and
wherein said linking arrangement comprises a second plurality of joints providing said probe with three degrees of freedom independently of said first plurality, movement of said second plurality of joints not being sensed.
2. A system as in claim 1, wherein said attaching device is capable of attaching the linking arrangement to a work bench.
23. A dental surface tracer including a dental probe having six degrees of freedom, comprising:
a mounting device which is capable of being mounted to a reference location with respect to a given jaw and defining a base plane;
a first link which is integral with said mounting device;
substantially coplanar second, third and fourth links defining a plane of movement; said second link being pivotally mounted to said first link so that said plane of movement is movable above and below said base plane; first means for generating electrical signals representative of such movement;
said second, third and fourth links being jointed together to have predetermined ranges of relative angular motion so that a distal end of said fourth link is movable over a predetermined area in said plane of movement; whereby said distal end has three degrees of freedom; second means for generating electrical signals representative of such movement;
gimbal means supporting said probe and attached to said distal end of said fourth link, for permitting said probe to move with three degrees of freedom without any movement of said first through fourth links;
whereby said probe can move with respect to said reference location with six degrees of freedom.
24. A tracer as in claim 23, wherein all of said links and gimbal means are sized for being accommodated within the human mouth.
25. A tracer as in claim 24, wherein said second, third and fourth links are jointed to provide greater than 90.degree. of relative angular motion between each pair of adjacent links.
26. A tracer as in claim 25, wherein substantially 100.degree. of relative angular motion is provided.
30. A dental surface tracer including a probe with a tip that can be moved to trace a given dental surface, comprising:
a mounting device for mounting said tracer to a stable reference location and defining a base plane;
a first plurality of links which are substantially coplanar and define a plane of movement; said links being pivotably attached to said mounting device so that said plane of movement makes a variable angle with said base plane; a distal one of said first plurality of links being movable in two dimensions within said plane of movement;
means for generating electrical signals representative of movements of said probe tip, as a function exclusively of movements of said first plurality of links;
a dental handpiece supporting said probe; and
a second plurality of links which hold the handpiece and are attached to said first plurality of links;
said second plurality of links holding said probe tip at all times at a fixed location in said plane of movement with respect to said distal link of said first plurality of links; and permitting said handpiece to move about three axes without moving said probe tip from said fixed location.
31. A tracer as in claim 30, wherein said entire tracer exclusive of said handpiece is sized to be accommodated within the human mouth.
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Brochure, "Announcement-Procera Station Installed", Nobelpharma, Feb. 1991. Brochure, "DCS--Titansystem Dux 1", Gim-Alldent, Germany. Matts Andersson et al., "Clinical results with titanium crowns fabricated with machine duplication and spark erosion", Acta Odontol Scand 47, pp. 279-286 (1989). Brochure, "Capture 3-Dimensional Position Data Instantly From Any Object--The Perceptor", Micro Control Systems, Inc.
Patent number: 5131844
Inventors: Paul J. Marinaccio (East Orleans, MA), Bruce Nappi (Reading, MA), Khushroo M. Captain (Cambridge, MA), Alan J. Lane (Lexington, MA)
Application Number: 7/682,001
Current U.S. Class: Having Gauge Or Guide (433/72); 128/776; Coordinate Movable Probe Or Machine (33/503); Dental (33/513)