AT397876B - Microtome - Google Patents

Abstract

Microtome, especially an optomicrotome, having an electric drive device 19 for the relative movement of blade 9 and object 7, and having an electronic control device 20 which drives the drive device 19 in order to change the speed of the drive device 19. In a portion S2 of the cutting path, in which the removal of this section takes place, there is a relatively low cutting speed. In order to return the moving part, for example the object stage or the blade, following the removal of the section, into the position before the respectively subsequent cutting process, a higher return speed is provided. In order to optimize the cutting process and, if necessary, to reduce the cycle time, the invention provides for the course of the relative speed between object 7 and blade 9 (cutting speed) within the portion S2 of the cutting path to deviate from the course of a constant speed. <IMAGE>

Description

ΑΤ 397 876 Β

The invention relates to a microtome, in particular an ultramicrotome, with an electrical drive device for the relative movement of knife and object and with an electronic control device which controls the drive device for changing the speed of the drive device, one in a cutting path section in which the cutting takes place there is a lower cutting speed and there is a higher return speed for returning the moving part, for example the specimen bar or the knife, after the cut has been removed into the position before the next cutting process that follows in each case.

To remove cuts from an object (preparation) by means of a knife, the object according to the prior art is moved relative to the knife or vice versa the knife is moved relative to the object. For microtomes, especially ultramicrotomes, electric drives are increasingly used for this movement, because in contrast to manual drives using a handwheel, a lever or a handle on a sliding carriage, the path speed of the specimen or knife that is decisive for the quality of the cuts is used reproduce exactly and can eliminate the manipulation forces that constantly change during manual operation and the resulting irregularities in the cutting thicknesses. These measures are therefore apart from special high-performance microtomes for light microscopic histology and for materials science, particularly in the field of semi-thin section technology (section thicknesses around 0.25 µm to 2.5 µm) and to an even greater extent in the field of ultramicrotomy (section thicknesses around 0 , 01 um to 1.0 um: see: H. Sitte, Ultramikrotomie, mta-Journal No. 10, Umschau-Verlag Breidenstein GmbH, Frankfurt 1983, as well as: H. Sitte and K. Neumann, Ultramikrotomie and apparatus aids for the ultramicrotomy, in: G. Schimmel and W. Vogel !, collection of methods of electron microscopy, Wissenschaftliche Verlags-GmbH Stuttgart, 11th delivery, 1983, here: in particular section D, sn 37 to 42) state of the art. In particular, in the last-mentioned device type, there is also the need to keep the time span between two successive cuts (&quot; cycle duration &quot;) as small as possible with regard to the never avoidable temperature changes and the resulting length changes in precision mechanics as a result of the thermal expansion. This would be possible without any problems if you could either choose the path speed of the moving part very high or the length of the path very short. However, both of the measures mentioned are out of the question for several reasons. A high path speed of the moving part in the range above 10 mm / sec causes a disturbing irreversible deformation ("compression") of the cuts in most objects and in many cases also releases high-frequency vibrations ("Chatter": see: H. Custom, ultramicrotomy - common problems and mistakes, in: Supplement Microscopy / Electron Microscopy, GIT-Verlag, Darmstadt, January 1982). A reduction in the path length of the moving part is due to the different dimensions of the object and the constantly changing position of the area of interest and the area selected for the cutting preparation, as well as the frequently changing geometry of the knives, especially the glass knives used in ultramicrotomy, and thus the constantly changing Relative position of the cut surface and the knife edge to the object or knife holder is very limited in its extent. In addition, in ultramicrotomy it is often necessary to lower the moving object at least 2 mm, optimally 5 mm below the knife edge, since this is the only way to form &quot; water bridges &quot; between the cut surface of the specimen and the front surface of the knife provided with a water-filled collecting basin (cf. in particular Figs. 7 and 10 in H. Sitte, 1982, 1.c.). A major step forward was the introduction of the so-called `` changeable drive '', in which the moving part only moves slowly in the area where the cut is removed (`` cutting window ''), but moves quickly on the rest of its path (`` return area '') , so that the cycle time can be kept comparatively short without the disadvantages of a stronger compression of the cuts or vibrations and the regularity of the cutting sequence can thereby be improved.

In order to reduce disturbing vibrations when changing the speed, a microtome has already been proposed (DE-C1-32 23 347), in which a range of linearly decreasing or linearly increasing speed is provided between the web section of high return speed and the web section of low cutting speed an overall steady course of speed is achieved. As with all other microtomes of the prior art, the course of the speed in the cutting path section in which the actual cutting takes place is constant.

The object of the present invention is to create a microtome, in particular an ultramicrotome of the type mentioned at the beginning, with which an optimized cut removal is possible with a short duration of the cutting cycle.

According to the invention, this is achieved in that the course of the relative speed between the object and the knife (cutting speed) within the cutting path section (S2) deviates from the course of a constant speed. 2nd

AT 397 876 B

Such a non-constant speed profile during the cutting process (cutting removal), i.e. while the object and the knife are in contact, can keep the speed and thus the shock when the knife touches the object low at the beginning of the cutting path section. At the same time, however, it is possible to increase the speed after the first critical gating phase while cutting is still taking place. On the one hand, this makes it possible to shorten the entire cycle time without having to accept the disadvantages of cutting the preparation (object) too quickly. In addition, such an increase in the relative speed between the object and the knife in the cutting path section, that is to say during the actual removal of the cut, is advantageous in some cases, for example in the case of cuts of frozen material, with regard to an optimal cut quality.

According to a preferred embodiment, the speed increase in the cutting path section can take place essentially linearly. Such a linear increase can be achieved in particular using relatively simple electronic means. In special applications, a speed curve can also be advantageous, in which the cutting speed in the cutting path section preferably increases linearly from a constant speed and then continues in the cutting path section again. At the present state of control electronics for motors, however, it is also not difficult to realize an essentially smoothly increasing, preferably exponentially increasing speed curve in the cutting path section, which can be ideally adapted to the respective requirements.

In addition to the above-mentioned speed increases during the cut removal, it is advantageous, for example in the case of objects with harder inclusions, to lower the cutting speed in at least one area of the cutting path section compared to the speed at the beginning of the cutting path section. You can achieve optimal cutting results even with difficult preparations without having to slow down the cycle time significantly.

According to a preferred embodiment of the invention, it is advantageously provided that the device for changing the speed profile in the cutting path section has at least one manually operable setting element for changing the speed profile. It is thus possible for the operator of the microtome or ultramicrotome to change the course of the cutting speed in the actual cutting path section during the cut removal in order to further optimize the cutting results.

In order that a setting of the cutting speed profile that has been made once and is recognized as advantageous is also retained for the subsequent cuts of a cutting series, it can be provided according to a preferred embodiment of the invention that an encoder or a similar rotational angle-registering element is connected to the drive device or a part driven thereby and that the control device has a memory for recording at least one speed curve, preferably traversed in a setting cycle and detected by the encoder or the like, and the control device, in conjunction with the encoder or the like, automatically sets a speed curve in the subsequent cycles that corresponds to one of the speed curves stored in the memory corresponds. The stored speed profiles can be pre-programmed. However, it is also possible to read these speed profiles into the memory in a first setting cycle (Lemvor process), in which the operator manually influences the speed profile, for example.

In addition to the manually changeable or preprogrammed speed profiles described above, there is also the option of automatically adapting the speed profile to the conditions for the respective cut. For this purpose, according to a preferred embodiment of the invention, at least one sensor is provided for recording the forces resulting from the cutting of the cuts or the changes to the microtome caused by these forces. The control device can now change the speed curve in the cutting path section depending on the sensor signals of this force sensor. At the same time, it is possible to show the current cutting forces or the cutting force curve on a display. An embodiment is particularly advantageous in which the control device regulates the speed profile in the cutting path section in such a way that the cutting force detected by the sensor remains constant during the entire cutting process.

An advantage of an automated speed sequence defined by the control device is that the movement sequence of the entire cutting series can be exactly reproduced or optimally adapted to the respective circumstances. You can then achieve uniform cutting thicknesses and cutting qualities.

However, it is also possible to manually intervene in the automatic sequence during the cutting operation in order to adapt the speed curve to special conditions, e.g. if from metho- 3

AT 397 876 B reasons the cutting speed must be corrected.

It can also be provided that the decisive parameters (e.g. cutting speed curve, cycle duration, maximum return speed, cutting forces) are shown on a display and / or can be changed using separate setting elements. For example, with regard to the universal use of this drive system, an extension of the cycle duration (regardless of the set cutting speed and duration) seems desirable if paraffin or plastic embeddings are cut at normal temperature and the cuts have to be continuously removed from the knife, as this longer cycle time is advantageous.

Further advantages and features of the invention and its configuration result from the following description with reference to the accompanying drawings. Show in these drawings

1: a vibrating rod ultramicrotome with motor change drive in a schematic top view and side view,

2: the relative movement of the object to the knife in an alternating drive according to the prior art in a more enlarged schematic representation corresponding to the side view in FIG. 1,

Fig. 3: a speed-time diagram for the movement sequence at the state of

Technology,

4: a speed-time diagram for the movement sequence in an exemplary embodiment of the invention,

5 and 6: speed-time diagrams of further movement sequences according to the invention.

The vibrating rod ultramicrotome shown schematically in a top view and side view in FIG. 1 is largely of a conventional type. On the stand 1, on the one hand the bearing bracket 2 is attached, to which the intermediate lever 4 is articulated via the bearing 3 and to which the specimen carrier rod 6 is articulated via the bearing 5 is at the front end of the preparation 7. On the other hand, the knife, for example a glass knife 9, is fastened to the stand 1 on a cross support 8 with the cutting edge 10, on which there is usually a collecting basin 12 filled with water 11 for the removal of the cuts when cutting in the room temperature range. The oscillating up and down movement of the specimen carrier rod 6 (&quot; vibrating rod ultramicrotome &quot;) with the specimen 7 takes place around the bearing 5 and is controlled according to FIG attached support profile 15 corresponds. The drive shaft 13 is supported on both sides in the elements 16/16 ′ fastened to the stand base 1 and, in addition to the handwheel 28, carries the pulley 17, which is connected to the electric motor 19 via an elastic transmission 18. The speed of the motor 19 is controlled via an electronic control device 20, which is connected either to a cam disk 21 or to an encoder 25 coupled via transmission elements 22/23/24, which can alternatively also be coupled directly to the drive shaft 13 (25 '). The control via the cam disc 21 can be carried out by a switching element 26 which is connected to the control device 20. The switching of the speed of the motor 19 by means of this element 26 can either be done without contact (e.g. light barrier) or through an intermittent contact between the elements 21 and 26 (e.g. microswitch) (see Austrian Patent 316 893 as stated above). In the course of the automatic drive, the object 7 is guided downwards over the cutting edge 10 of the knife 9 to take the cut. After reaching the lowest position, the object 7 is pulled back by pivoting the intermediate lever 4 around the bearing 3 (mechanism not shown in FIG. 1; cf. also FIG. 2), and then upwards away from the knife edge 10 into the highest position above the Knife edge 10 out and advanced again. At the same time, the object 7 or the knife 9 is advanced by a separate feed system (not shown in FIG. 1) by the preselected amount of cutting thickness, so that a cut is again taken from the knife edge 10 in the next cycle, which cut onto the surface of the water 11 swims in the pool 12.

Fig. 2 shows an enlarged section of the object-knife area of a microtome with variable drive control according to the prior art. 3 shows the associated speed profile in a speed-time diagram. Between the switchover point Ud and the switchover point Ua, the preparation moves via the points BCDA with the high return speed. In the cutting window Si between the switchover points Ud and Uc, the specimen (object 7) moves relative to the knife 9 at a substantially lower constant cutting speed. In order to avoid vibrations when switching from the high return speed to the low cutting speed or from the cutting speed to the high return speed, there is a linearly decreasing range Y between the points Ua and Ub and between the switching points Uc and Ud Speed increasing section Z is provided. 4th

AT 397 876 B

The duration for passing through the cutting window lying between the switching points Ub and Uc is denoted by tSi. The actual cutting path section Sa, in which the object is in contact with the knife during the removal of the cut, lies within this cutting window Si. The duration for passing through this cutting path section S2 is denoted by ts2 in FIG. 3.

In the microtome according to the invention, the course of the relative speed between object 7 and knife 9 (cutting speed) within the cutting path section S2 now deviates from the course of a constant speed.

4, the speed in the cutting path section S2 increases linearly after a short constant range, ie during the actual cutting decrease, and then continues again continuously. At the switchover point Uc, the low-vibration switchover to the high return speed then takes place via a renewed linear increase. Such linearly decreasing or increasing speed profiles can be implemented relatively easily, for example in a manner similar to that already provided for in the prior art. As already mentioned, such a speed profile in the cutting path section S2, which is not constant in contrast to the prior art, enables the cut quality to be optimized and the cycle time to be reduced as the speed profile increases.

5 shows two further speed profiles of an exemplary embodiment of the microtome according to the invention, the speed in the cutting path section S2 initially increasing exponentially in order to then pass into the linearly increasing range which leads to the high return speed. As in the exemplary embodiment described in FIG. 4, the speed at the start of the actual cutting path section S2 is low, so that the shock occurring when the knife and the object meet is also low. After this first critical cutting phase, however, it is advantageous in many cases to increase the speed in the cutting path section.

In particular in the case of specimens with hard spots, however, it can also be advantageous to lower the speed in the cutting path section S2 in some areas, as is shown in FIG. 6.

The elements responsible for the speed sequence are largely implemented in the electronic control device 20. This control device, which defines the speed curve and in particular the non-constant speed curve in the cutting section S2, contains, for example, a central microprocessor unit 30 which receives signals from the control and switching elements 21 and 26 or from the encoder 25 (25 ') about the relative position of object 7 and knife 9 are supplied. The microprocessor unit 30 can contain a programmable memory device 31, in which several speed profiles are preprogrammed. These speed profiles can then be called up by the user. The central microprocessor unit 30 then controls the electric motor 19 via the line 37, so that the object 7 moves relative to the knife 9 in the selected speed course.

According to a preferred embodiment of the invention, however, it is also possible for the electronic control device 20 to have a device for changing the speed profile in the cutting path section. This changing device for the speed profile can have, for example, an adjusting element (e.g. rotary potentiometer 32) for manually changing the speed profile in the cutting path section (see FIG. 1). This means that the user can change the speed curve in the cutting path section by hand, if necessary, especially when observing at the same time through a stereo microscope.

A speed profile which is traversed in a setting cycle and detected by the encoder 25, 25 'can be stored in a memory 34. This enables the control device 20 in conjunction with the encoder 25, 25 'to automatically run the same speed profile in subsequent cycles. It is therefore only necessary to adjust the speed profile in the cutting path section in a cutting series in a first setting process.

In addition to the changes in the speed profile described above in the cutting path section S2, there is also the possibility of an automatic adaptation of the speed profile to specific operating conditions. According to a preferred embodiment, a sensor is provided for recording the forces resulting from the cutting of the cuts or the changes to the microtome caused thereby. In the exemplary embodiment shown in FIG. 2, this sensor is designed as a piezo element 33 below the knife 9. Alternatively or additionally, however, other sensors are also possible, for example the strain gauge 33 ′ shown in FIG. 1 on the underside of the specimen carrier rod 6 for absorbing the resulting cutting forces or the effects on the mechanics of the ultramicrotome. In any case, the sensor signals are fed to the central microprocessor unit 30, which automatically reduces the cutting speed, for example, when a cutting force above a threshold value is determined. In a further embodiment, it is 5

Claims (14)

AT 397 876 B possible that the control device regulates the speed curve in the cutting path section in such a way that the cutting force detected by the sensor or its effects remains constant during the cutting removal. In special applications, it can be advantageous to intentionally extend the cycle time. For this purpose, an adjusting element 35 is provided, by means of which the cycle duration can be varied independently of the selected cutting speed and duration. The central microprocessor unit then determines and realizes the speed curve as a function of the desired entered cycle duration. Finally, a display device 36 is also provided for displaying the parameters of interest for the cutting preparation, in particular the preselected speed and / or the duration of the cycle. It is also conceivable to graphically show the speed curve on a display. The present invention can be implemented in different embodiments and combinations in adaptation to the different needs of practice and to the different constructions of microtomes, semi-thin section devices and ultramicrotomes, without losing their inventive character. In particular, the invention can be implemented with different supports and movements of the object or knife that differ from the system according to FIG. 1, for example on a chute or basic slide microtome, insofar as the movement takes place automatically or via a motor drive and via an encoder or a corresponding registering element and an electronics connected to it is controlled. It is irrelevant for the implementation of the invention whether the object 7 is moved by means of an electric motor 19 shown in FIG. 1 via a transmission 18 and a drive shaft 13 or, for example, by means of a rotating coil drive in the manner of the LKB ultrotome systems (cf. Fig. 63 in H.Sitte and K.Neumann, 1983, lc) or on a straight vertical or horizontal path (see Fig. 1 and 2 of the same publication). It is also irrelevant whether and in what way a retraction of the object 7 or the knife as part of a &quot; single pass movement &quot; (cf. Section D of the same publication) as long as the cut is made with a path speed of the moving part that is comparatively much lower for resetting. Finally, the mechanical or electrical elements by means of which the various parameters which are decisive for the cutting preparation or for the operation of the instrument can be set or from which data can be read, can be designed differently as required. 1. Microtome, in particular ultramicrotome, with an electric drive device for the relative movement of the knife and the object and with an electronic control device which controls the drive device to change the speed of the drive device, a lower one in a cutting path section in which the cutting takes place Cutting speed is present and there is a higher return speed for returning the moving part, for example the specimen rod or the knife, after the cut has been removed into the position before the next subsequent cutting process, characterized in that the course of the relative speed between object (7) and knife (9 ) (Cutting speed) within the cutting path section (S2) deviates from the course of a constant speed. 2. Microtome according to claim 1, characterized in that the relative speed between the object (7) and knife (9) increases after a low cutting speed at the beginning of the cutting path section (S2) while the cut is being removed. 3. Microtome according to claim 2, characterized in that the speed increase in the cutting path section (S2) is substantially linear. 4. Microtome according to claim 2, characterized in that the speed increase in the cutting path section (S2) is substantially smooth, preferably exponential. 5. Microtome according to one of claims 1-4, characterized in that the cutting speed in the cutting path section (S2) preferably increases linearly from a constant speed and then continues in the cutting path section (S2) again constantly. 6. Microtome according to one of claims 1-5, characterized in that the cutting speed in the cutting path section (S2) compared to the speed at the beginning of the cutting 6 AT 397 876 B path section (S2) is reduced in some areas. 7. Microtome according to one of claims 1 to 6, characterized in that the control device driving the drive device (19) has a device (32, 30; 33, 30) for changing the speed profile in the cutting path section (S2). 8. Microtome according to claim 7, characterized in that the device for changing the speed profile in the cutting path section (S2) has at least one manually operable adjusting element (32) for changing the speed profile. 9. Microtome according to one of claims 1 - S, characterized in that with the drive device (13, 18, 19) or a part driven thereby, an encoder (angle encoder 25, 25 ') or a similar rotational angle-registering element is connected, that the Control device (20) has a memory (34) for recording at least one, preferably run in a setting cycle and the like, by the encoder. has detected speed curve, and the control device (20) in conjunction with the encoder (25, 25 ') or the like. automatically determines a speed curve in the subsequent cycles which corresponds to one of the speed curves stored in the memory (34). 10. Mlrotome according to claim 7, characterized in that it has at least one sensor (33, 33 ') for recording the forces resulting from the separation of the cuts or the changes caused by these forces. 11. Microtome according to claim 10, characterized in that the control device (20) changes the speed curve in the cutting path section (S2) as a function of the sensor signals. 12. Microtome according to claim 11, characterized in that the control device (20) regulates the speed profile in the cutting path section (S2) such that the cutting force detected by the sensor remains constant during the cut removal. 13. Microtome according to one of claims 1 to 12, characterized in that the desired cycle duration with a separate adjusting element (35) can be varied independently of the selectable cutting speed and duration. 14. Microtome according to one of claims 1 to 13, characterized in that a display device (36) is provided for displaying the parameters of interest for the cutting preparation, in particular the speed profile, the duration of the cycle and optionally the cutting forces. Including 3 sheets of drawings 7