GB2123167A

GB2123167A - Microtome having a forward-feed control system for the specimen arm and/or the knife

Info

Publication number: GB2123167A
Application number: GB08317044A
Authority: GB
Inventors: Dr Helmuth Sitte; Walter Bilek
Original assignee: C Reichert Optische Werke AG
Current assignee: C Reichert Optische Werke AG
Priority date: 1982-06-30
Filing date: 1983-06-23
Publication date: 1984-01-25
Also published as: FR2529676A1; JPS5957139A; GB2123167B; SE8303691D0; GB8317044D0; SE8303691L; DE3224433A1; CA1188945A

Abstract

A microtome, especially an ultramicrotome, is disclosed in which a foward-feed system for the specimen arm and/or knife of the microtome comprises, a stepping motor which is controlled by a pulse generator and which shifts the specimen arm and the knife relative to each other by an appropriate amount of forward-feed in accordance with a forward-feed value which is set at one of a plurality of preselector switches. In order to facilitate quick switching-over from one forward-feed amplitude to another, permitting the selection of forward-feed amplitudes which differ by an order of magnitude, for example if semi-thin sections are to be produced during a run of ultra-thin sections, the forward-feed amplitudes set by the preselector switches can be switched according to choice to the pulse generator for the stepping motor, by means of a changeover switch. This arrangement enables the operator to alter the forward-feed amplitude by one manual action, without disturbing the ongoing operation.

Description

SPECIFICATION Microtome having a forward-feed control system for the specimen arm and/orthe knife The invention relates to a microtome having a forward-feed control system for the specimen arm andlorthe knife, and is especially applicable to an ultramicrotome.

In orderto set the section-thickness of the th in sections which are produced by means of a microtome, the specimen arm, carrying the preparation or specimen, is shifted towards the knife, before each cutting stroke, by an amount corresponding to the section-thickness. In a known ultramicrotome, this is effected by means ofaforward-feed mechanism. It is desirableto be able to set an ultramicrotome to produce section-thicknesses which differ by several orders of magnitude, so that, for example, when starting to cut up a preparation-block, considerably thicker sections can initially be removed until a sectioning area which can be used for a thin section proper has itself been obtained on the preparation.In a known ultramicrotome, two preselector switches are provided forthis purpose, the switches permitting substantially different section-thicknesses to be set by the setting offorward-feed values. In an arrangement of thins type, the forward-feed value desired for ultra-thin sectioning is set at one of the preselector switches, while the forward-feed value desired during the intial cutting process is set at the other preselector switch.When the sectioning surface which produces the first usable thin section is reached on the preparation, the preselector switch which defines the forward-feed amplitude during the initial cutting process isturned to the stop position, so that the ultramicrotome now operates with the forwardjeed which corresponds to the desired ultra-thin sectionthickness.

During the production of ultra-thin sections, itis frequently desired to produce a number of semi-thin sections, or it is necessary to "leap-frog" unusable parts of the preparation, for which purpose the forward-feed is increased. In the case ofthe known ultramicrotome, this requires that the first preselector switch be reset This proves to be troublesome, particularlyduring the deliberate inclusion of a few semi-thin sections, not only because resetting involves a delay, but also because the operator is distracted from the operations taking place on the preparation, so that itis difficultto exclude the possibility of mistakes.

The object ofthe invention isaccordinglyto provide a forward-feed control system, of the type initially mentioned, which permits different forward-feed amplitudes to be selected quickly, without hindering the ongoing work, and without involving any substantial disturbance in the ease with which the cutting process can be observed.

According to one aspect ofthe invention there is provided a microtome comprising a specimen arm for holding a specimen to be sectioned, a knife for cutting sectionsfrom said specimen, a drivemeansfor reciprocating the specimen arm so that said arm moves in a cutting stroke past the knife and in a return stroke, and forward-feed means for incrementally advancing the specimen arm towards the knife before each cutting stroke,theforward-feed meanscomprising a stepping motor, drive translation means for translating the motion produced by the stepping motor into linear motion of The. specimen arm, a pulse generator connected to the stepping motorto supply voltage pulses to operate said motor, electrical circuit means adapted to provide two or more alternate outputs, and selector means connected between the electrical circuit means and the pulse generator for connecting a selected one of the outputs to the pulse generator,wherebythespecimen arm may be advanced by a selected one of two or more different increments before each cutting stroke.

In another aspect of the invention, the forward-feed means advancestheknife instead of, or additionally to, the specimen arm.

The desired differentforward-feed values can be set, and remain set, at the various preselector switches,thesevalues normally differing by orders of magnitude. If, for example, it is intended to "fit in" a number of semi-thin sections during the production of ultra-thin sections,the operator needs onlyto have set the desi red forwa rd-feed amplitude atthe appropriate preselectorswitch, afterwhich he can changeover, from the ultra-thin section-thickness, to the semi-thin section-thickness, by means of a single manual action atthe changeoverswitch. There is no needtosearch again for the desired section-thickness, norto set it at the preselector switch.

Digital-type presetting switches are expediently provided as the preselector switches. In one embodi ment ofthe invention there are provided two stepping motors, of which one is connectedtothe specimen arm and the other is connected to the knife-holder, a preselector switch being assigned to each stepping motor.

Further advantages and features of the invention are evidentfrom the following description of an illustrative embodiment, with reference to the drawings, in which: Figure 1 shows a purely diagrammatic side view of an ultramicrotome, partially sectioned; and Figure 2 shows a forward-feed control system, employed in the ultramicrotome shown in Figure 1.

The ultramicrotome represented in Figure 1 includes a specimen carrier 1 ,which is fastened to a specimen arm 2 and which holds at its front end a specimen or preparation 3. A drive device, which is not shown in more detail, guides the specimen arm 2, and hence the specimen carrier 1 with the preparation, past a knife 4. In addition, a forward-feed device, which is aiso not shown in detail, shifts the specimen arm 2, towards the knife 4, by a preselectable forward-feed amplitude, so that thin sections of a predeterminablethickness can be produced at each cutting stroke. In the design ofthe devices for driving the specimen arm, and its mode of operation,the ultramicrotome does not differ from known ultramic rotomes, and will therefore not be described in more detail.

The control system for the forward-feed device represented schematically in Figure 2 makes it possibleto control the amplitude oftheforward-feed travel executed bythespecimen arm 2. Forthispurpose,the specimen arm 2 is coupled to a stepping motor 5, through a drive translation arrangement which is not shown in detail. The stepping motor 5 receives a pulsed voltage 7 which is supplied via a power-output state 6 incorporating a pulse generator. The specimen arm 2 is moved onwards by a defined number of steps, corresponding to the number of pulses. The total number of steps corresponds, in each case, to the forward-feed amplitude atthe specimen arm 2.

Digital-type presetting switches 8,9 are provided for the purpose of presetting forward-feed values of different amplitudes, these presetting switches being capable of being connected, in alternation, to the power-output stage 6. Connection is effected via a changeover switch 10. The desired ultra-thin sectionthickness is, for example, set at a preselector switch 8, and a semi-thin section-thickness is set at the preselector switch 9, the latter being intended to be brought into action during the operation. By simply resetting the changeover switch 10, the operator of the ultramicrotome can consequently set a forward-feed amplitude, at the stepping motor S,which differs by an order of magnitude, for example by a power of 10.

One embodiment of the invention provides a plurality of preselector switches, of the abovementioned type, for a plurality offorward-feed amplitude ranges, in place of the two digital-type preselector switches 8,9 which areshown in the illustrative embodiment, thus enabling, for example, an even largersection-thickness to be selected forthe initial cutting operation.

Claims

1. A microtome comprising a specimen arm for holding a specimen to be sectioned, a knife for cutting sections from said specimen, a drive means for reciprocating the specimen arm so that said arm moves in a cutting stroke past the knife and in a return stroke, and forward-feed means for incrementally advancing the specimen arm towards the knife before each cutting stroke, the forward-feed means comprising a stepping motor, drive translation means for translating the motion produced by the stepping motor into linear motion ofthe specimen arm, a pulse generatorconnected to the stepping motorto supply voltage pulses to operate said motor, electrical circuit means adapted to provide two or more alternate outputs, and selector means connected between the electrical circuit means and the pulse generatorfor connecting a selected one of the outputs to the pulse generator, whereby the specimen arm may be advanced by a selected one oftwo or more different increments before each cutting stroke.

2. A microtome according to Claim 1, wherein the electrical circuit means comprise a respective pre selector switch associated with each of said outputs, whereby the output may be adjusted.

3. A microtome according to Claim 2, wherein the preselector switches are digital presetting switches.

4. A microtome comprising a specimen arm for holding a specimen to be sectioned, a knife for cutting sectionsfrom saidspecimen, a drive meansfor reciprocating the specimen arm so that said arm moves in a cutting stroke pastthe knife and in a return stroke, and forward-feed means for incrementally advancing the knife towards the specimen arm before each cutting stroke, the forward-feed means comprising a stepping motor, drive translation means for translating the motion produced by the stepping motor into linear motion of the knife, a pulse generator connected to the stepping motorto supplyvoltage pulses to operate said motor, electrical circuit means adapted to provide two or more alternate outputs, and selector means connected between the electrical circuit means and the pulse generatorfor connecting a selected one of the outputs to the pulse generator, wherebythe knife may be advanced by a selected one oftwo or more different increments before each cutting stroke.

5. A microtome according to Claim 4, wherein the electrical circuit means comprise a respective preselector switch associated with each of said outputs, wherebythe output may be adjusted.

6. A microtome according to ClaimS, wherein the preselector switches are digital presetting switches.

7. A microtome comprising a specimen arm for holding a specimen to be sectioned, a knife for cutting sections from said specimen, a drive means for reciprocating the specimen arm sothatsaid arm moves in a cutting stroke past the knife and in a return stroke, first forward4eed means for incrementally advancing the specimen arm towards the knife, second forward-feed means for incrementally advancing the knife towards the specimen arm, each forward-feed means comprising electric motor means and electrical circuit means controlling the operation ofthe motormeans,thetwo electrical circuit means being arranged such thatthefirstforward-feed means advances the specimen arm by a different increment to that by which the second forward-feed means advances the knife, and selector means connected between the electrical circuit means and the electric motor means for selectively operating oneofthetwo forward-feed means.

8. A microtome substantially as herein described with referenceto and as shown in the accompanying drawings.