A LID MECHANISM

Abstract: A lid mechanism (1) is provided for laboratory equipment, and especially for polymerisation chain reaction thermal cycle apparatus. The lid mechanism (1) includes a lid (9) movable between an open position, in wich a sample may be inserted into or removed from the equipment, and a closed position, in which a sample is prevented from being removed from the equipment. The lid mechanism (1) also includes a drive mechanism (5, 6, 7, 8) coupled to the lid (9) and operable to move the lid (9) between the open and the closed position.

Description: A Lid Mechanism The invention relates to a lid mechanism for laboratory equipment, for example, polymerisation chain reaction thermal cycle apparatus. Polymerisation chain reaction thermal cycle apparatus is commonly used when analysing DNA. The apparatus typically includes a sample tray that has a number of recessed walls into which samples are introduced. The sample tray is then positioned in a sample block in the apparatus and the lid, which has a heating plate on its underside, is pressed down onto the sample tray to clamp the sample tray between the sample block and the heating plate. The sample block is then heated cyclically over a period of time to cause a polymerisation chain reaction within the sample. After the thermal cycling process has been completed, the lid is removed from the sample tray. The sample tray is then removed from the sample block and the samples within the sample tray are analysed. Currently, automatic robotic machines are used to fill the sample wells in the sample tray, to position the sample tray in the heating block and to subsequently remove the sample tray from the heating block after the thermal cycling operation has been completed. However, human intervention is still required in order to close the lid on the apparatus. This reduces the efficiency of the apparatus as the apparatus can only be operated during working hours. Alternatively, it is necessary for personnel to operate on a shift basis if the apparatus is to be operated 24 hours per day. This second option lids to a higher cost for operation of the equipment. In accordance with the present invention, there is provided a lid mechanism for laboratory equipment, the lid mechanism comprising a lid movable between an open position in which a sample may be inserted into or removed from the equipment, and a closed position in which a sample is prevented from being removed from the equipment; and a drive mechanism coupled to the lid and operable to move the lid between the open and the closed position. An advantage of the invention is that by providing a lid mechanism which includes a drive mechanism it is possible to provide laboratory equipment, such as polymerisation chain reaction thermal cycle apparatus, with a lid which can be opened and closed without requiring manual intervention. Preferably, the laboratory equipment is polymerisation chain reaction thermal cycle apparatus. Preferably, in the closed position, the underside of the lid is pressed into engagement with a sample holder, in which a sample is located. Preferably, when the lid is in the open position, the lid is displaced from the sample holder in a vertical and a horizontal direction. Preferably, the drive mechanism comprises a rotating screw drive which rotates to move the lid in a linear motion. Preferably, when the lid is moved from the open to the closed position, the lid is moved in a first direction towards the sample holder to an intermediate position in which the lid is located above the sample holder and the drive mechanism then moves the lid in a second direction to move the lid from the intermediate position to the closed position. Preferably, where the laboratory equipment is polymerisation chain reaction thermal cycle apparatus, the lid includes a planar surface on the underside. Typically, where the laboratory equipment is polymerisation chain reaction thermal cycle apparatus, the sample holder is located in a sample block and when the lid is in the closed position, the sample holder is clamped between the sample block and the planar surface. Typically, the sample block and/or the planar surface may be heated to enable heating of a sample in the sample holder. Preferably, the sample block and/or the planar surface are metallic. Preferably, the drive mechanism further comprises a cam follower arrangement to move the lid from the intermediate position to the closed position. Typically, when the lid is in the open position, the lid may be pivoted with respect to the drive mechanism to permit access to the underside of the lid, for example, for cleaning the underside of the lid. An example of a lid mechanism in accordance with the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a polymerisation chain reaction thermal cycle lid block module showing a lid in an open position; Figure 2 is a top view of the lid block module of Figure 1 ; Figure 3 is a cross-sectional view of the lid block module along the line AA of Figure 2; Figure 4 is a side view of the lid block module shown in Figure 1 with a partial cross-section view along the line BB of Figure 2; Figure 5 is an enlarged view of the partial cross-sectional shown in Figure 4; Figure 6 is a perspective view of a cam and slide plate forming part of the cam mechanism shown in Figure 5; Figure 7 is a rear view of the lid block module shown in Figure 1 ; Figure 8 is a perspective view of the lid block module shown in Figure 1 with the lid in a pivoted position; Figure 9 is a perspective view of the lid block module with the lid in an intermediate position; Figure 10 is a top view of the lid block module shown in Figure 9; Figure 1 1 is a cross-sectional view along the line CC of Figure 10; Figure 12 is a side view of the lid block module of Figure 10 with a partial cross-sectional view along the line DD of Figure 10 showing the cam mechanism; Figure 13 is an enlarged view of the partial cross-sectional view shown in Figure 12; Figure 14 is a perspective view of the lid block module showing the lid in a closed position; Figure 15 is a top view of the lid module shown in Figure 14; Figure 16 is a cross-sectional view along the line EE of Figure 15; Figure 17 is a side view of the lid block module of Figure 15 with a partial cross-sectional view along the line FF of Figure 15 showing the cam mechanism; and Figure 18 is an enlarged view of the partial cross-sectional view shown in Figure 17. Figure 1 shows a perspective view of a lid block module 1 for polymerisation chain reaction thermal cycle apparatus. The lid block module 1 includes a base 2 with two sample blocks 3 mounted thereon. Also mounted on the base 2 is a drive plate 4 which supports two lead screws 5. Each lead screw 5 includes a drive nut 6 which engages with a cam 7, 8 mounted on the side of a lid (or heated cover) 9. The lid module 1 plugs into and is supported on a base module (not shown). The base module includes firmware and a control system to control the heating and thermal coupling to the sample blocks 3 and also provides heating to platen 10 (see Figure 3) located on the underside of the lid 9. As shown in Figure 3, the lid 9 includes an outer cover 11. Within the outer cover 11 is located a support member 12 which extends between two pins 13 which extend out of the side of the cover 11 and engage in a cam profile 40 in each of the cams 7, 8. The platens 10 are mounted on the support member 12 by means of a base plate 14 attached to each platen 10 and mounting members 15 which couple the base plates to the support member 12. Figure 3 also shows pivotable rear guards 16, 17 that cover each of the lead screws 5. The rear guards 16, 17 are not shown in Figures 1 and 2 for clarity. A side view of the lid block module 1 is shown in Figure 4 in which a cut away section shows a cross-sectional view of the cam mechanism along the line BB of Figure 2. Also shown in Figure 4 are cooling fins 47 that extend from the bottom of the sample blocks 3. An enlarged view of the cross-sectional view of the cam mechanism is shown in Figure 5. The cam 7 slidingly engages with a right hand side slide plate 18. A perspective view of the right cam 7 and the right slide plate 18 is shown in Figure 6. The left cam 8 is symmetrically opposite to the right cam 7. The right slide plate 18 has two holes 19 that permit the slide plate 18 to be fixed to the right hand side of the external cover 11. The right cam 7 is able to slide with respect to the lid 1 and the right slide plate 18 due to the slide grooves 20, 21 in the right cam 7 and the right slide plate 18, respectively. A symmetrically opposite left-hand slide plate 38 is provided which engages with the left cam 8 in a similar manner. The slide plate 18 also includes a spring-loaded interlocking shaft 22 that is biased by a spring 24 within the slide plate 18 to the position shown in Figure 5. The position of the interlocking shaft 22 as shown in Figure 5 is when the spring 24 is in a fully extended position and end 25 of the shaft 22 protrudes above surface 26 of the slide plate 18. The shaft 22 is limited by the amount that end 25 can protrude above surface 26 by a circlip 27. In the position shown in Figure 6, the surface 23 of the cam 7 has been pushed over the end 25 of the shaft 22 thereby depressing the shaft 22 to compress the spring 24 so that the interlocking shaft 22 moves to the position shown in Figure 6. Figure 7 shows a rear view of the lid module. Mounted on the rear ends of each of the lead screws 5 is a drive wheel 26 around which is entrained a drive belt 27. Mounted on the drive plate 4 are two guide pulleys 28 and a motor 29. The motor 29 includes a drive shaft 30 on which is mounted a motor gear 31. The motor gear 31 drives the belt 27 to rotate the drive wheels 26 so as to cause rotation of the lead screws 5. The motor 29 is reversible so that the drive shaft 30 and the motor gear 31 (and therefore, the lead screws 5) may be driven in either direction. Each of the drive nuts 6 is shaped so that it has a flatted side portion which butts against the side of the cams 7, 8. Therefore, on rotation of the lead screws 5, the drive nuts 6 are prevented from rotating so that they move along the lead screws 5 to move the lid 9 towards or away from the drive plate 4 depending on the direction of rotation of the lead screws 5 which is determined by the direction of rotation of the motor 29. Figures 9 and 10 show the lid 9 in an intermediate position after it has been moved by rotation of the lead screws 5, by means of the motor 29 and the drive belt 27, from the open position shown in Figures 1 and 2. In the position shown in Figures 9 and 10, the lid 9 is located above the sample blocks 3 and the platen 10 are in the positions shown in Figure 11. In this position, the lid 9 has been moved as far away as possible from the drive plate 4 and further movement away from the drive plate 4 is prevented by the cover 11 hitting a stop member (not shown). From Figures 12 and 13, it can be seen that despite the movement of the lid 9 from the position shown in Figure 1 to the position shown in Figure 9, the cam mechanism, and in particular, the location of the cams 7, 8 with respect to the slide plates 18, 38 and the location of the pins 13 within the cam track 40 of the cams 7, 8, is in the same position as that shown in Figures 4 and 5 for the lid 9 in the open position shown in Figure 1. Further rotation of the lead screws 5 in the same direction drives the cams 7, 8 forward with respect to the slide plates 18, 38 as the slide plates 18, 38 are prevented from moving forward further as they are fixed to the cover 11. This further movement of the cams 7, 8 with respect to the slide plates 18, 38 also causes the cams 7, 8 to move forward with respect to the lid 9 and the pins 13. This relative movement of the cams 7, 8 with respect to the slide plates 18, 38 and the pins 13 brings the surface 23 of the cams 7, 8 into contact with the upper end 25 of the interlocking shaft 22 and further forward movement of the cams 7, 8 causes the interlocking shaft 22 to be depressed into a locking aperture 41. Simultaneously, the pins 13 are moved downward due to the forward movement of the cams 7, 8 to the position shown in Figures 14 to 18 in which the cams 7, 8 have been moved forward by the lead screws 5 as far as possible. In this position, the interlocking shaft 22 is locked in the depressed position which engages with the locking aperture 41 and the pins 13 have been moved fully downward by the cam profile 40. The downward movement of the pins 13 causes downward movement of the support member 12 and therefore a downward movement of the platen 10 towards the sample blocks 3 until the platen 10 contact against the sample blocks 3, as shown in Figure 16. Hence, when a sample tray is inserted into the sample block 3 and the lid 9 is moved to the position shown in Figure 16, the sample tray is clamped between the sample block 3 and the underside of the platen 10. In order to return the lid from the position shown in Figures 14 to 17 to the open position, the rotation of the motor 29 is reversed which reverses rotation of the lead screws 5. This pulls the cams 7, 8 backward with respect to the slides 18, 38 as the slides 18, 38 are locked to the base 2 by the interlocking shaft 22. When the cams 7, 8 move back to the position shown in Figures 12 and 13 the pins 13 have been raised by the cam track 40 which lifts the platen 10 to the position shown in Figure 11 and the interlocking shaft 22 moves to the position shown in Figure 13 to release the slide plates 18, 38 from the base 2. Further rotation of the lead screws 5 in the same direction then pulls the lid 9 back to the open position shown in Figures 1 and 2. During the polymerisation chain reaction that occurs during heating of samples in a sample tray clamped between the sample blocks 3 and the platen 10, there is a tendency for some of the sample to become deposited on the underside of the platen 10. Therefore, it is necessary to be able to have access to the underside of the platen 10 in order to clean the surfaces, as necessary. Therefore, the rear guards 16, 17 are pivotable to the position shown in Figure 8. This permits the lid 9 to be pivoted upward as shown in Figure 8 to permit access to the underside surfaces of the platen 10 to permit cleaning of the platen 10. This pivoting motion of the lid 9 is facilitated by u-shaped hooks 45, 46 on the cams 7, 8 which hook over the lead screws 5 but do not encircle the lead screws 5 and therefore, permit the hooks 45, 46 to be engaged with and disengaged from the lead screws 5 and drive nut 6. As shown in Figure 8, the lid block module 1 also includes two fixed front guards 32, 33 which are not pivotable and cover the front portions of the lead screws 5. Advantages of the invention are that it permits motorised and robotic motion of the lid 9 between the open and closed positions without requiring human intervention. This has the advantage of facilitating 24 hour operation of the polymerisation chain reaction thermal cycle apparatus without requiring human intervention.

Claims: CLAIMS 1. A lid mechanism for laboratory equipment, the lid mechanism comprising a lid movable between an open position in which a sample may be inserted into or removed from the equipment, and a closed position in which a sample is prevented from being removed from the equipment; and a drive mechanism coupled to the lid and operable to move the lid between the open and the closed position. 2. A lid mechanism according to claim 1 , wherein the lid mechanism is for polymerisation chain reaction thermal cycle apparatus. 3. A lid mechanism according to any of the preceding claims, wherein the lid is displaced from the sample holder in a vertical and a horizontal direction when the lid is in the open position. 4. A lid mechanism according to any of the preceding claims, wherein the drive mechanism comprises a rotating screw drive which rotates to move the lid in a linear motion. 5. A lid mechanism according to any of the preceding claims, wherein the drive mechanism moves the lid in a first direction from the open position to an intermediate position and then moves lid in a second direction from the intermediate position to the closed position. 6. A lid mechanism according to any of the preceding claims, wherein the lid includes a planar surface on the underside. 7. A lid mechanism according to any of the preceding claims, wherein the drive mechanism further comprises a cam follower arrangement to move the lid from the intermediate position to the closed position. 8. A lid mechanism according to any of the preceding claims, wherein when the lid is in the open position, the lid may be pivoted with respect to the drive mechanism. 9. Laboratory equipment comprising a lid mechanism according to any of the preceding claims. 10. Laboratory equipment according to claim 9, wherein the lid mechanism is in accordance with any of the preceding claims, and further comprising a sample block for receiving a sample holder, and when the lid is in the closed position, the sample holder is located between the sample block and the underside of the lid.

Inventors: SHIN HON SIU, SHIN, HON, SIU
Applicants: PE HOLDING B V, SHIN HON SIU, PE HOLDING B.V., SHIN, HON, SIU
Application year: 1999
Main classification: G01N33
IPC codes: B01L3, B01L7