Title of Invention	A HAND-HELD PIPETTE FOR TAKING A LIQUID SAMPLE WITHOUT TEMPERATURE DRIFT
Abstract	The hand-held pipette (2) comprises: a part (4) having an internal portion (22); and a temperature sensor (40). The sensor is placed to measure a temperature of the internal portion.

Full Text

A HAND-HELD PIPETTE FOR TAKING A LIQUID SAMPLE WITHOUT; TEMPERATURE DRIFT The invention relates to hand-held pipettes. Document EP-0 873 731 discloses a hand-held pipette provided with two temperature sensors for measuring the temperature of the air flowing at the bottom portion of the pipette while a liquid sample is being taken. The measured temperature values enable the air temperature to be taken into account when controlling the movement of the piston in order to improve the accuracy of the volume taken. Nevertheless, in practice, the measurement accuracy of the volume still turns out to be insufficient. Furthermore, the disposition of two sensors in the bottom portion of the pipette complicates the arrangement thereof. An object of the invention is to improve the accuracy with which the volume taken is measured, and to do so by taking temperature drift into account. To this end, the invention provides a hand-held pipette comprising: • a part having an internal portion; and • a temperature sensor; the sensor being placed so as to measure a temperature of the internal portion. Thus, the sensor makes it possible to take account of the real temperature of the pipette, e.g. as a result of its heating due to prolonged manipulation by the user. This data can be taken into account either for displaying a volume value that is to be taken, or for controlling the piston, or for both simultaneously. Knowledge of the temperature of the internal parts of the pipette, such as the screw, the body, or other components, makes it possible to correct for deviations in stroke due to expansion of the parts, for example. The pipette of the invention may also present at least one of any of the following characteristics: • the sensor is in contact with an inside face of the portion; • the part is stationary; • the part presents a position that is adjustable in order to adjust the volume to be taken; • the part has a portion extending outside the pipette; • the part is designed to come into contact with a hand of a user; • the part is a handle; • the pipette is a motor-driven pipette; and • the pipette is not a motor-driven pipette. The invention also provides a method of displaying a value for a volume of a sample to be taken by means of a hand-held pipette, comprising the steps consisting in: • measuring a temperature of an internal portion of a part of the pipette; and • displaying a value for a volume to be taken, taking the measurement into account. The method of the invention may also present at least any one of the following characteristics: • the corrected value for the volume is determined from the measurement and a raw volume value; • the corrected value is displayed; ' the raw value is displayed; • while taking account of the measurement, it is determined whether the raw value for the volume is less than or greater than a corrected value for the volume and a sign is displayed indicating less than or greater than, depending on circumstances; and • the sign is displayed together with the corrected value. Other characteristics and advantages of the invention appear further from the following description of a preferred embodiment and of a variant given as non-limiting examples and with reference to the accompanying drawings, in which: • Figure 1 is a longitudinal axial section view of a pipette in a preferred embodiment of the invention; • Figure 2 is a view on a larger scale showing the middle portion of the Figure 1 pipette; • Figure 3 is a flow chart showing how temperature is taken into account while the pipette is in operation; and • Figure 4 is a flow chart showing a variant of the operation shown in Figure 3. A preferred embodiment of a pipette of the invention is described below with reference to Figures 1 and 2. This pipette is essentially of the same type as that which is described in documents WO 01/76747, WO 01/76748, WO 01/76749, WO 01/76750, WO 01/76751, WO 01/76752, WO 01/76753, and FR-A 2 80J 344. Only those "cEaracteristics that relate to the invention and that are not described in those prior documents are therefore described herein. To summarize, the pipette 2 comprises a body 4, a control rod 6 provided at its top end with an actuator button 8, an adjustment screw 10, a liquid-crystal screen 12 for displaying information, in particular the value of a volume to be taken, an electronic circuit 14 for controlling the display and the pipette, and a device 16 including a button 18 enabling a removable cone (not shown) to be ejected, said cone being secured to a bottom end 20 of the pipette in a manner that is known per se. The rod 6 serves to control a piston 21 for sucking in a sample of liquid for taking into the cone, or for expelling it. The body 4 is made as a single piece of plastics material- It has internal portions 22, 24, and 26, together with external portions such as the portion 28. The body 4 is a stationary hollow part that acts as a positioning reference for a large number of internal parts of the pipette, in particular for parts such as the screw 10 of position that is adjustable relative to the body in order to adjust the value of the volume that is to be taken. Thus, a large number of parts of the pipette are secured to the body 4 directly or indirectly. The body 4 presents a rear window 30 through which the display 12 can be seen, which window is itself covered by a glass 32 extending beyond the window both upwards and above all downwards in order to cover the internal portion 22 of the body in the rear portion of the pipette. The body forms a pipette handle and thus constitutes one of the parts of the pipette that comes directly into contact with the hand of the user while the pipette is being manipulated. The internal portion 22 of the body 4 presents, in particular, an inside face 34 defining a chamber 36 in which the rod 6 for actuating the piston 22 is movable. The pipette includes a temperature probe 40 received in a cavity of the inside face 34 of the portion 22, in the top portion of the chamber 36. The sensor constituted by the probe 40 is arranged to measure the temperature of the internal portion 22. It can be seen that it is situated close to the screw 10, to the rod 6, and to the electronic circuit 14, which circuit is itself liable to generate heat. The temperature probe is thus implanted close to those portions that are the most subjected to thermal expansion and it serves to discover the temperature of the mechanical components involved in the sample-taking system. The sensor 40 is connected via its electrical connection wires 42 to the electronic circuit 14 so that the circuit can take account of the temperature value sensed by the sensor. In the present example, temperature is taken into account in compliance with the flow chart shown in Figure 3. Thus, during an initial step, the user makes use of controls provided for this purpose on the pipette to set manually the nominal or raw value of the volume of the sample of liquid that is to be taken. This step corresponds to block 44 in Figure 3- This information is transcribed by an encoder 4 6 so that it can be understood by the processor in the electronic circuit 14. The processor also receives from the sensor 40 information about the temperature of the internal portion 22. Given that the specifications of the pipette, and in particular the specifications for setting the nominal value of the volume to be taken, are determined for a pipette at 20°C, the processor responds to the temperature value supplied by the sensor 40 to determine whether it is necessary to correct the nominal value. It can happen, for example when the user manipulates the pipette over a long duration, that the pipette becomes heated in contact with the user's hand so that the mechanism of the pipette takes on a new setting because of the thermal expansion of certain parts• This known phenomenon is referred to "handwarming". Starting from the temperature value supplied by the sensor, the processor makes use of predetermined correction equations and/or matrices (such as tables) to determine firstly whether any correction of the value is needed, and if so to determine the corrected value that is to be supplied. Thus, in this example, the processor causes the display 12 to display firstly the nominal value of the volume as set by the user, as mentioned in block 48 of Figure 3, and secondly the correction value together with a sign indicating the direction of the correction, as mentioned in block 50. This sign is a "-" sign if, in the presence of a correction value that is greater than the nominal value, there is a danger of underdosing, or on the contrary a "+" sign if, in the presence of a correction value smaller than the nominal value, there is a danger of overdosing. To sum up, three items of information are delivered by the display 12 to the user. Provision could be made for the electronic circuit of the pipette to be programmed in such a manner that this type of operation and display is activated only when the correction due to temperature becomes significant. Predetermined values can be selected for discriminating between circumstances in which a correction is significant, and other circumstances. In this mode of operation, the user can thus adjust the pipette as a function of the new indication given by the block 50, thereby taking account of the temperature of the pipette. A variant form of operation is shown in Figure 4. This time, after the value to be taken has been set manually in accordance with block 44 and transcribed by the encoder 46 for the processor 14, the processor takes account of the temperature value supplied by the sensor and displays a single correction value as shown in block 52. This correction value is determined by the processor as a function of the nominal value requested by the user and as a function of the temperature value supplied by the sensor. The user thus has only one item of information which is the corrected value of the volume to be taken. Thus, in this mode of operation, characterized by an automatic correction of the display, the display of the pipetting value automatically includes the correction. The display varies as a function of temperature and the user does not need to make any modification. The correction method thus constitutes a process that is transparent for the user, i.e. that the user does not see taking place. The user adjusts the pipette so as to obtain the desired volume value on the display. The pipette of the invention is thus made independent of various kinds of heating such as those to which it can be subjected during handling on the part of the user. This mitigates the various expansions of the mechanical system that usually give rise to drift in the sample-taking stroke, thereby having a direct influence on the quantity taken. The invention makes it possible to conserve the same accuracy in terms of volume over a wider range of operating temperatures for the pipette, e.g. over a range of 10°C to 30°C. Naturally, numerous modifications can be made to the invention without going beyond the ambit of the invention. In the above, it is shown how the processor 14 takes account of temperature information in order to correct the value that is to be displayed. Provision could be made for the processor also to take other parameters into account such as atmospheric pressure or indeed the type of cone, in particular the volume of the cone secured to the bottom portion of the pipette. Under such circumstances, the pipette can perform successive corrections on the value of the volume to be displayed in order to display the final value. More generally, when displaying a value for the volume that is to be taken, provision can be made for the temperature measurement to be used in conjunction with a raw volume value to determine a corrected volume value for display or for it to be used as a basis for determining a volume value that is to be displayed. In the present example, the pipette is a hand-held pipette that is not motor driven. The invention could be applied to a hand-held pipette that is motor driven. The sensor could be disposed in such a manner that it measures the temperature of a moving part inside the pipette presenting a position that is adjustable, for example, in order to adjust the volume of the liquid sample to be taken. The part could thus be the screw. WE CLAIM : 1. A hand-held pipette (2) comprising: a part (4) having an internal portion (22); and a temperature sensor (40); the pipette being characterized in that the sensor is placed so as to measure a temperature of the portion. 2. The pipette as claimed in the preceding claim, wherein the sensor (40) is in contact with an inside face (34) of the internal portion. 3. The pipette as claimed in claims 1 or 2, wherein the part (4) is stationary. 4. The pipette as claimed in claim 1 or claim 2, wherein the part presents a position that is adjustable in order to adjust the volume to be taken. 5. The pipette as claimed in any preceding claim, wherein the part (4) has a portion (28) extending outside the pipette. 6. The pipette as claimed in any preceding claim, wherein the part (4) is designed to come into contact with a hand of a user. 7. The pipette as claimed in any preceding claim, wherein the part (4) is a handle. 8. The pipette as claimed in any preceding claim, wherein the pipette is a motor—driven pipette. 9. A method of displaying a value for a volume of a sample to be taken by means of a hand—held pipette (2), the method being wherein it comprises the steps consisting in: measuring a temperature of an internal portion(22)of a part (4) of the pipette; and displaying a value for a volume to be taken, taking the measurement into account. 10. The method as claimed in the preceding claim, wherein the corrected value for the volume is determined from the measurement and a raw volume value. 11. The method as claimed in the preceding claim, wherein the corrected value is displayed. 12. The method as claimed in claim 10 or claim 11, wherein the raw value is displayed. 13. The method as claimed in any one of claims 9 to 12, wherein, while taking account of the measurement, it is determined whether the raw value for the volume is less than or greater than a corrected value for the volume and a sign is displayed indicating less than or greater than, depending on circumstances. 14. The method as claimed in the preceding claim, wherein the sign is displayed together with the corrected value.

Documents:

1854-chenp-2006 abstract duplicate.pdf

1854-chenp-2006 claims duplicate.pdf

1854-chenp-2006 description (complete) duplicate.pdf

1854-chenp-2006 drawings duplicate.pdf

1854-chenp-2006-abstract.pdf

1854-chenp-2006-claims.pdf

1854-chenp-2006-correspondnece-others.pdf

1854-chenp-2006-correspondnece-po.pdf

1854-chenp-2006-description(complete).pdf

1854-chenp-2006-drawings.pdf

1854-chenp-2006-form 1.pdf

1854-chenp-2006-form 18.pdf

1854-chenp-2006-form 26.pdf

1854-chenp-2006-form 3.pdf

1854-chenp-2006-form 5.pdf

1854-chenp-2006-other documents.pdf

1854-chenp-2006-pct.pdf