AU701118B2 - Coverslip pick-up and laydown apparatus - Google Patents

Description

1- P100/0011I Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT GGb.

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ORIGINAL

Name of Applicant: Actual Inventor: Address for service in Australia: Invention Title: AUSTRALIAN BIOMEDICAL CORPORATION LIMITED Stuart Stanley ELLIOTT CARTER SMITH BEADLE 2 Railway Parade Camberwell Victoria 3124 Australia COVERSLIP PICK-UP AND LAYDOWN APPARATUS The following statement is a full description of this invention, including the best method of performing it known to us -2- TITLE: COVERSLIP PICK-UP AND LAYDOWN APPARATUS This invention relates to an instrument for automatically applying coverslips i to microscopic specimen slides in the field of histology and pathology. More I particularly the invention relates to a method and apparatus, within such an instrument, for reliably lifting and separating a single glass coverslip from a stack of coverslips.

A machine of the kind in question is described in Applicant's earlier patent application No. PCT/AU95/00035 and the present invention relates to improvements in the lifting and separating apparatus described in the earlier application.

°o 1 0 Whilst the method and apparatus for picking up coverslips from the top of a Sstack of coverslips, as described in the earlier application, is generally successful in separating a single coverslip from the stack the number of steps involved in the S method and the fact that in some cases the coverslips are bonded together so strongly in the stack that more than one is picked up at a time is deleterious to the machine i Is operation and causes inconvenience to the user.

Accordingly it is an object of the present invention is to provide an improved method and apparatus for removing a single coverslip from a stack of coverslips.

00o0 Therefore, the invention provides a method of lifting and separating a single coverslip from a stack of coverslips including raising the ends of a top coverslip of 20 the stack whilst applying a downward force midway between said ends thereby flexing the coverslip and subsequently moving the top coverslip from the stack, and momentarily removing and restoring said downward force to provide a flexural pulse to said top coverslip.

A further form of the invention provides a coverslip transfer head for picking 2s up a coverslip from the top of a stack of coverslips, wherein said transfer head comprises a plunger arranged between two spaced suction cups such that when the plunger is in an extended position over a stack of coverslips the plunger extends vertically downwardly beyond the lowermost position of the suction cups, said suction cups being inclined outwardly and downwardly relative to the vertical axis of the plunger such that when a coverslip is held by the two suction cups and the I 3 plunger is extended the coverslip is flexed in a concave configuration, and a solenoid and a spring associated with said plunger for moving said plunger in opposite directions, respectively.

In order that the invention may be more readily understood particular embodiments will now be described with reference to the accompanying drawings wherein: Figure 1 is a schematic elevation of a pick-up and transfer head according to an embodiment of the invention; and Figures 2a-2c are schematic side elevations of a coverslip lay-down head o according to an embodiment of the invention, showing the head in various positions in the course of laying a coverslip on a slide.

Referring now to Figure 1 the pick-up and transfer head 10 is shown to have *inclined surfaces 11 on the underside thereof with a suction cup arrangement 12 mounted on each surface 11. As a consequence of the inclination of the surfaces 11 Is the suction cup arrangement 12 extend outwardly and downwardly from the transfer head 10 relative to a central vertical axis x-x. Each suction cup arrangement 12 is provided with a suction cups 26.

0 A plunger 13 is mounted on the transfer head 10 and extends along the vertical axis. The plunger 13 is biased by spring 14 into a downward or lowermost 20 position as shown in Figure 1. A solenoid 15 is provided on the plunger 13 whereby actuation of the solenoid by an electric pulse causes the plunger 13 to retract against the force of spring 14 to an upper or retracted position (not shown) wherein the lowermost point of the plunger 13 is vertically above the plane of the suction cups 26. In other words in the retracted position the plunger 13 has little or no contact with a coverslip 16 being held by the suction cups 26.

In Figure 1 there is shown a coverslip magazine 17 which contains a stack 18 of coverslips ar,d the magazine 17 is shown in a raised position enabling the uppermost coverslip to be contacted by the suction cups 26.

In operation of an instrument incorporating the pick-up and transfer head 10 e the coverslip magazine 17 containing a stack 18 of coverslips is raised until the top

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-4coverslip comes into contact with the bottom end of the plunger 13 and then the suction cups 26. A vacuum is then applied co the suction cups 26 which firmly grip the top coverslip 16 adjacent the respective ends thereof. The force of the spring 14 and the angular orientation of the suction cups causes the coverslip 16 to flex in a concave configuration. Once in this position the magazine 17 is retracted downwardly and the top coverslip is retained by the pick-up and transfer head As the coverslip magazine 17 is retracted downwards the solenoid 15 is energised momentarily causing the plunger to lift against the force of spring 14. The solenoid is then de-energised which releases the plunger causing it to deliver a gentle flexural 10 pulse to the coverslip 16. This has the effect of breaking the adhering bond between the coverslip 16 and any further coverslip which may be adhered to the underside of the top coverslip 16. This allows the underneath coverslip to return to the magazine to be ready for the next pick-up cycle.

Referring now to Figures 2a, 2b and 2c there is shown a lay-down head 19 1s for laying a coverslip 16 on a slide 25 in a manner which facilitates use of a minimal amount of mountant and less probability of void formation between the coverslip and slide. The lay-down head 19 is rotatable about axis y-y and is also moveable vertically up and down in the direction of the arrow 20 shown in Figure 2a. The lay-down head 19 has an inclined undersurface 21 from which depends a 20 suction cup 22 which is inclined at an angle to the vertical axis z-z of the lay-down head 19. A pivotal lever 23 is mounted on the lay-down head 19 and is spring biased by a spring (not shown) in a direction anti-clockwise as viewed in Figures 2a 2c inclusive. The lever 23 is pivotally mounted on shaft 24 and assumes a rest position as shown in Figure 2a by means of a stop (not shown) on the lay-down head 19. The lower end of the lever 23 incorporates a pressure pad in the form of a Teflon head (not shown) which reduces friction when the head slides along a coverslip as will become apparent hereinbelow.

A latch mechanism (also not shown) is provided on the lay-down head 19 to latch the lever 23 in a pivoted position clockwise from the initial position (as viewed in Figures 2a-2c) and approximately as shown in Figure 2c. Detaching of the lever PRS:AM:2845;DIV 21 May 199 I 23 occurs when the lay-down head 19 is rotated about the axis y-y through 180° to receive a further coverslip which is delivered to the lay-down head 19 by the pick-up and transfer head The major problem in laying the coverslip 16 on the slide 25 is that voids occur in the mountant as it is spread over the slide 25 and of course any such voids effect the ability to microscopically observe the specimen contained on the slide Research by the present applicants has observed that void free results are, in the main, obtained by controlling the shape of the advancing mountant "wavefront" as the coverslip and slide are gradually brought together. The present invention achieves a uniformly advancing wave-front, thereby avoiding creation of voids, by a combination of the manner in which the mountant is applied to the slide and the manner in which the coverslip is laid down onto the slide.

Specifically, the mountant (not shown) is applied in a thin strip or streak up the centre of the slide (rather than a blob at one end of the slide) and, by virtue of Is the angled suction cup 22 and the spring assisted pressure pad provided on lever 23, the mountant is caused to advance along the slide 25 with a uniform wavefront extending across the width of the slide. The action of the pressure pad at the end of lever 23 is to progressively squeeze the coverslip against the slide as the lay down action proceeds. The line of action of the pressure pad moves up the coverslip creating a greater curvature of the coverslip and therefore a uniformly advancing wavefront in the mountant. This occurs as the lay-down head 19 moves downwardly towards the slide 25 causing the suction cup 22 to place the coverslip 16 on the slide. The use of the :pring assisted pressure pad (lever 23) has enabled a considerable reduction in the quantity of mountant required to ensure a void free 2s result. Whereas in applicants previous invention as described in Application No.

PCT/AU95/00035 a central streak containing about 115 microlitres of mountant was required in order to achieve acceptable results, the invention described herein achieves even better results (a higher percentage of acceptable products) using only about 30 microlitres of mountant. The width of the pressure pad is about 15 mm which is considerably less than the width of the coverslip which is approximately 26mm.

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i -6- It should be apparent to persons skilled in the art that the resent invention provides considerable improvements over prior art instruments of the kind in question. The unique pick-up and transfer head 10 provides a simple operation for ensuring that only one coverslip is selected from a stack of coverslips during each cycle of machine operation by providing a flexural pulse which breaks the adhering bond between the top coverslip and the next coverslip in the stack. Furthermore, the provision of a spring assisted pressure pad that works in conjunction with an angled suction cup on the lay-down head ensures a greater curvature of the coverslip as it is laid onto the slide and the combined action progre.sively squeezes the coverslip S 10to against the slide as the lay-down action proceeds. The mountant therefore proceeds in a uniform wavefront and the likelihood of voids occurring in the mountant is considerably reduced.

It should be also mentioned that the parallel operation of the pick-up and transfer head 10 and the lay-down head 19 allows multiple activities to occur is simultaneously which facilitates greater machine throughput. This results in a more efficient instrument for automatically applying coverslips to microscopic specimen slides.

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Claims (6)

1. A method of lifting and separating a single coverslip from a stack of coverslips including raising the ends of a top coverslip of the stack whilst applying a downward force midway between said ends thereby flexing the coverslip and subsequently moving the top coverslip from the stack, and momentarily removing and restoring said downward force to provide a flexural pulse to said top coverslip.

2. A method according to claim 1, wherein said raising of the ends of the top coverslip is effected by angled suction cups and said downward force is provided by a spring load plunger having a solenoid to overcome the spring force.

3. A coverslip transfer head for picking up a coverslip from the top of a stack of coverslips, wherein said transfer head comprises a plunger arranged between .two spaced suction cups such that when the plunger is in an extended position over a stack of coverslips the plunger extends vertically downwardly beyond the lowermost position of the suction cups, said suction cups being inclined outwardly Si*, s and downwardly relative to the vertical axis of the plunger such that when a coverslip is held by the two suction cups and the plunger is extended the coverslip is flexed in a concave configuration, and a solenoid and a spring associated with said plunger for moving said plunger in opposite directions, respectively.

4. A coverslip transfer head as defined in claim 3, wherein said spring a 20 forces the plunger into said extended position and said solenoid withdraws said plunger against the force of said spring to a retracted position where the plunger is above the level of a plane through said suction cups.

A method of lifting and separating a single coverslip from a stack of coverslips, substantially as hereinbefore described with reference to Fig. 1 of the accompanying drawings.

6. A coverslip transfer head substantially as hereinbefore described with reference to Fig. 1 of the accompanying drawings. DATED: 21 May 1998 CARTER SMITH BEADLE Patent Attorneys for the Applicant: AUSTRALIAN BIOMEDICAL CORPORATION LIMITED PRS:AMh:S4a IV 21 May 9IS ii I r A coverslip pick-up and transfer head 10 comprises a pair of spaced suction cups 26 which are angled downwardly and outwardly. A spring loaded plunger 13 in an extended condition extends below the suction cups such that when a c-ver slip 16 is held by the suction cups it is flexed in a concave shape. A solenoid 15, when energised, retracts the plunger against the spring force. In use a coverslip magazine 17 containing a stack of coverslips is raised under the head causing the plunger to retract until the suction cups contact the coverslips. Vacuum is applied to the suction cups and the magazine lowered whereby the coverslip is held by the suction cups and flexed into a concave shape. The solenoid is energised momentarily causing the plunger to retract and extend thereby delivering a gentle flexural pulse Sto the coverslip causing any further coverslip adhered to the underside of the top n. coverslip to be released and returned to the magazine. A coverslip laydown head 19 includes a pivotal lever 23 which is spring biased to provide a progressive force along the coverslip as it is layed on a slide at an ever decreasing angle to thereby cause mountant on the slide to spread evenly over the slide with a uniform wavefront. 0o 0 PRS:AM:284s5:DIV 21 May 199