Cutting – With means to convey work relative to tool station – Plural passes of diminishing work piece through tool station
Reexamination Certificate
1999-01-29
2001-07-03
Rada, Rinaldi I. (Department: 3724)
Cutting
With means to convey work relative to tool station
Plural passes of diminishing work piece through tool station
C083S733000, C083S856000, C083S915500
Reexamination Certificate
active
06253653
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a microtome.
DE 31 44 120 A1 has disclosed a traversing microtome which contains a base and a carriage which can be moved along slide rails. The cutting blade is in this case fixed immovably to the base, while the specimen holder is arranged on the carriage. In order to make the cut, the carriage is moved manually along its guide on the base.
However, traversing microtomes are also known in which the cutting blade is mounted on the carriage and the specimen holder is mounted in a fixed position on the base.
In both types of traversing microtome, the specimen is cut by way of a relative movement between the cutting blade and the object.
Another type of microtome is known from DE 195 31 524 C1. The rotary microtome described in this document has an object carriage on which there is an object holder for the specimen which is to be cut. The object holder is moved up and down on the rotary microtome in a vertical path. During this movement, the specimen is guided past a blade which is arranged in a fixed position on the rotary microtome.
In this case too, the specimen is cut by way of a relative movement between the cutting blade and the object. In both types of known microtome, it is necessary to return the object or the cutting blade to the starting position after a cutting operation has taken place. During this return movement, it is imperative that the cutting blade does not collide with the specimen if clean specimen cuts are to be produced. In both cases, this is achieved by the cutting blade or the specimen being retracted a certain amount by means of a feed device, so that the moving component can be moved past the fixed component. In the event of a further cutting operation, the specimen or the cutting blade is advanced again by this certain amount plus the cut thickness set.
Both types of microtome have proven themselves in practice. The need for a return movement to a starting position after a cutting operation has taken place means that microtomes of this nature are unable to achieve rapid cutting sequences. In addition, these oscillating movements result in considerable forces during the acceleration or deceleration of the moving components, and these oscillations have to be compensated for, entailing a high level of mechanical outlay. Otherwise, there is a risk of vibrations being transmitted to the microtome, resulting in unusable thin-cut sections.
The document “Leica SP 1600—Saw Microtome, Instruction Manual, V0.0 English—11/86, from Leica Instruments GmbH” has disclosed a saw microtome for cutting very hard objects, such as bones, ceramic, etc. As its cutting blade, the saw microtome has a diamond-tipped annular saw which rotates at 600 rpm. The object to be cut is arranged, together with the object holder, on a rotationally movable arm. The arm is pivoted extremely slowly toward the annular saw in order to carry out a sawing cut. Following the sawing cut, the arm has to be moved back again. This microtome does not allow continuous cutting or the cutting of tissue samples.
DE 26 40 966 A1 and JP 63-241442 A have disclosed cutting devices in which a disk-like cutting blade is driven by a motor. Arrangement [sic] of this nature are used to produce thin-cut sections of very hard materials, such as bone.
DE-C 263 871 has disclosed a microtome with a fixed blade and a rotating object holder. The cutting blade is arranged in a blade holder which is fed onto the object holder using mechanical means for setting the cut thickness. A simple crank handle is used to drive the microtome described.
AT 172 605 and U.S. Pat. No. 3,191,477 have each disclosed a microtome with a rotatably mounted disk. A specimen holder is arranged on the end side of the disk, so that the axis of rotation of the disk is approximately perpendicular to the cutting plane. In this arrangement, the object is guided past the cutting blade along an orbital path, so that the cut section acquires a cylindrical profile. However, in many cases this cylindrical profile cannot be used during a subsequent microscopic examination, since the cut section has to be placed flat beneath the microscope.
DD 5 620 has disclosed a motor-driven, revolving blade carrier in which the object holder is advanced by means of an eccentric disk and a lever which acts thereon. This arrangement provides for a parallel arrangement of object and blade during the cutting operation. However, the object is advanced not by means of a linear component but rather using a lever and an eccentric disk.
U.S. Pat. No. 3,884,563 describes a microtome with a motor-driven, revolving blade carrier in which the object holder is advanced by means of a carriage. The microtome also has a cryostat and a film camera which is used to film the specimen during the cutting operation. In this microtome, the cut sections are not examined further, but rather are disposed of via a collection container.
U.S. Pat. No. 2,753,761 and GB-C 654 123 describe disk microtomes in which the object holder is arranged on a disk and the blade holder is arranged fixedly on the microtome. In this case, the cutting advance takes place by way of a parallel displacement of the disk with respect to the base, using a thermocouple and a spindle, or by way of a parallel displacement of the blade holder on the base. There is no provision in these documents for motor-controlled feed.
U.S. Pat. No. 3,902,390 has disclosed a pocket microtome in which the cutting blade is arranged on a rotationally moveable arm and can be manually preloaded by means of a spring. This microtome is designed for portable use and is unsuitable for carrying out series of cuts.
SUMMARY OF THE INVENTION
Therefore, the object of the present invention is to optimize the relative movement between the cutting blade of the microtome and the object and, in so doing, to ensure a rapid and accurate sequence of cuts.
As a result of the rotating component on which either the object or the cutting blade is arranged there is no need for the blade or the object to be moved back following a first cutting operation. This eliminates the need for the reversing movement in order for the microtome to return to its starting position, and the mechanical outlay on avoiding vibrations can be minimized.
A further advantage lies in the fact that, in contrast to the known disk microtomes, a motor-controlled feed is provided for setting the cut thickness. A control circuit also allows different cut thicknesses to be preselected for a single specimen.
In a further configuration of the invention, there is provision for a plurality of object holders to be arranged on the rotating component, in order to carry out a plurality of cutting operations simultaneously. In this case, the object holders, together with the objects to be cut, may be grouped together next to one another on the outer circumference of the rotating component or next to one another in the direction of the center of the disk.
Providing a plurality of objects also makes it possible to cut into these objects together in a first phase, i.e. all the objects are cut during a single revolution of the component.
Arranging an angle-position encoder on the rotating component allows the position of the objects with respect to the cutting blade to be determined. It is then possible to use the control circuit to individually preselect the cutting sequence and the cut thickness for each single object. However, a precondition for this individual preselection is that it be possible to change the distance between the cutting blade and the object during operation. This is achieved by using the angle position encoder to determine the disk position and using the motor-driven feed and the control circuit to change the position of the cutting blade or of the object while the rotating disk is running.
As a result, the control circuit can be used to individually preselect the sequence of specimens to be cut and, in addition, to individually set an appropriate cut thickness.
REFERENCES:
patent: 1928689 (1933-10-01), Heys
patent: 2753761
Biehl Manfred
Laudat Andreas
Metzner Rolf
Scheck Peter
Vierling Juergen
Floves-Sáchez Omar
Foley & Lardner
Leica Microsystems Nussloch GmbH
Rada Rinaldi I.
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