Magnetic stirrer

Abstract

A magnetic stirrer (11) comprises a magnetic drive and a placement surface (17) for a laboratory vessel containing a substance to be stirred. The magnetic drive is designed to generate a magnetic field which varies such that a magnetic stirring element can be driven to produce a stirring motion in the laboratory vessel, in order to stir the substance. The magnetic stirrer (11) also comprises a heating device (15), which is designed to heat the placement surface in order to heat up the substance, and a display device (23), which is designed to display the current temperature of the placement surface.

Claims

1. A magnetic stirrer comprising: a magnetic drive and a placement surface for a laboratory vessel; said laboratory vessel, containing therein a substance to be stirred, wherein the magnetic drive is configured to generate a magnetic field varying such that a magnetic stirring element positioned in the laboratory vessel can thereby be driven to make a stirring movement to stir the substance; a heating apparatus that is configured to heat the placement surface to heat the substance; and a display apparatus comprising an illumination element controllable to transmit light; said display apparatus configured to display a respective temperature state of the placement surface, to control the illumination element to transmit light having respectively different illumination characteristics for the display of different temperature states of the placement surface and/or of different heating states of the heating apparatus, and to control the illumination element to transmit pulsing light of different pulse frequencies for a combined display of a switched off state of the heating apparatus and of different hot states of the placement surface.

2. The magnetic stirrer in accordance with claim 1, wherein the display apparatus is configured to control the illumination element to transmit light in accordance with a first illumination characteristic for a display of a switched on state of the heating apparatus; to control the illumination element to transmit light in accordance with a second illumination characteristic for a combined display of a switched off state of the heating apparatus and of a hot state of the placement surface; and/or to control the illumination element to transmit light in accordance with a third illumination characteristic for a combined display of a switched off state of the heating apparatus and of a cool state of the placement surface.

3. The magnetic stirrer in accordance with claim 2, wherein the display apparatus is configured to control the illumination element to transmit constantly illuminating light for the display of the switched on state of the heating apparatus.

4. The magnetic stirrer in accordance with claim 2, wherein the display apparatus is configured to control the illumination element to transmit pulsing light for the combined display of the switched off state of the heating apparatus and of the hot state of the placement surface.

5. The magnetic stirrer in accordance with claim 2, wherein the display apparatus is configured to control the illumination element to transmit no light for the combined display of the switched off state of the heating apparatus and of the cool state of the placement surface.

6. The magnetic stirrer in accordance with claim 2, wherein the display apparatus is configured to control the illumination element to transmit constantly illuminating light for the display of the switched on state of the heating apparatus; to control the illumination element to transmit pulsing light for the combined display of the switched off state of the heating apparatus and of the hot state of the placement surface; and/or to control the illumination element to transmit no light for the combined display of the switched off state of the heating apparatus and of the cool state of the placement surface.

7. The magnetic stirrer in accordance with claim 1, wherein respective illumination characteristics for displaying different temperature states of the placement surface differ with respect to a pulse frequency, a color and/or a brightness of the respective light transmitted by the illumination element.

8. The magnetic stirrer in accordance with claim 1, wherein the magnetic stirrer comprises an actuation element, with the display apparatus being provided at the actuation element.

9. The magnetic stirrer in accordance with claim 1, wherein the magnetic stirrer comprises a temperature sensor for detecting a respective temperature of the placement surface, with the display apparatus being configured to determine and display the respective temperature state of the placement surface in dependence on the respective temperature detected by means of the temperature sensor.

10. The magnetic stirrer in accordance with claim 1, wherein the magnetic stirrer comprises a base unit having a power supply for the magnetic drive, for the heating apparatus, and for the display unit, with the heating apparatus being formed separately from the base unit, and being arranged at the base unit, and having the placement surface; and with the display apparatus being provided at the base unit.

11. The magnetic stirrer in accordance with claim 10, wherein the heating apparatus is a hotplate.

12. The magnetic stirrer in accordance with claim 1, further comprising: an actuation element for switching and/or adjusting the heating apparatus, wherein the actuation element is a single element including a rocker switch, a push button, a rotary knob, a touch-sensitive input element, or similar; and a display apparatus arranged to encompass the actuation element; said display apparatus configured to display a respective temperature state of the placement surface and to display a respective heating state of the heating apparatus.

13. The magnetic stirrer in accordance with claim 1, further comprising: an actuation element for switching and/or adjusting the heating apparatus; wherein the display apparatus is integrated in the actuation element and the actuation element is a single element including a rocker switch, a push button, a rotary knob, a touch-sensitive input element, or similar.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The invention will be described in the following only by way of example with reference to the FIGURE.

(2) FIG. 1 shows an embodiment of a magnetic stirrer in accordance with the invention in a very simplified schematic representation.

DETAILED DESCRIPTION

(3) A magnetic stirrer 11 is shown in very simplified form in FIG. 1 as an example of a laboratory device having a residual heat display in accordance with the invention. The magnetic stirrer 11 comprises a base unit 13 that is configured as a flat parallelepiped having a chamfered upper front edge. A heating apparatus 15 that has a flat cylindrical shape is arranged at the upper side of the base unit 13. The upwardly facing front section of this shape is configured as a hotplate that can be heated. The front surface of the cylindrical shape simultaneously forms a placement surface 17 of the magnetic stirrer 11.

(4) A laboratory vessel comprising a substance to be stirred and/or to be heated can be placed on the placement surface 17 that is horizontally aligned on a conventional arrangement of the magnetic stirrer 11 with its lower side on a planar surface such as a tabletop. For the stirring of the substance, a magnetic stirring element, in the manner of a so-called flea, for instance, is introduced into the substance and can be driven through the lower side of the laboratory vessel to make a stirring movement.

(5) A magnetic drive, not visible from the outside, is provided in the interior of the magnetic stirrer 11 for this purpose. It is configured to generate a magnetic field in a region adjacent to the placement surface and above the placement surface, said magnetic field then being able to exert magnetic forces on the magnetic stirring element, in particular such that the magnetic stirring element at least substantially rotates about the cylinder axis of the cylindrical shape of the heating apparatus 15. In this manner, a stirring movement of the magnetic stirring element can be induced in the middle of the substance to be stirred by the magnetic drive provided in the interior of the magnetic stirrer 11.

(6) The heating apparatus 15 that can extend at least partly also into the interior of the magnetic stirrer 11 comprises at least one electrical heating element that thermally contacts the placement surface 17. The heating apparatus 15 can heat the placement surface 17 in this manner so that heat can be transmitted from the placement surface 17 to the respective substance placed on the placement surface 17 to heat the substance. So that the placement surface 17 is heated as homogeneously as possible, said front side of the cylindrical shape of the heating apparatus 15 comprises a material having a high thermal conductivity, in particular a metal. To avoid heat being transferred from the placement surface 17 to the base unit 13, a gap can be provided between a lower edge of the jacket surface of the cylindrical shape and the upper side of the base unit 13.

(7) The magnetic drive and the heating apparatus 15 are supplied with power by a common power supply that is integrated in the base unit and has a connector for connecting a mains plug. The magnetic drive and the heating apparatus 15 are adjustable at least to the extent that they can generally be switched on and off independently of one another to selectively stir and/or heat the respective substance.

(8) Said chamfer of the upper front edge of the parallelepiped shape of the base unit 13 forms an operating surface 19 of the magnetic stirrer 11 at which a plurality of actuation elements 21 are arranged for the adjustment of the magnetic stirrer 11.

(9) The actuation elements 21 in particular serve to switch the magnetic drive on and off and to set a speed of change of the magnetic field to thereby set the speed of the stirring movement or to switch the heating apparatus 15 on and off and to set a heating power of the heating apparatus 15 to set the speed of heating.

(10) Only a single one of these actuation elements 21 is shown that is formed as a flat push button or as a touch element and by whose actuation the heating apparatus 15 can be alternately switched on and off. A display apparatus 23 of the magnetic stirrer 11 is provided at the push button 21 and comprises as the illumination element 25 a light permeable illumination surface that is backlit by a light source in the form of multi-color LEDs. This illumination surface surrounds the at least substantially round push button 21 in annular form. The supply of the display apparatus 23 with power takes place via the same power supply that is also provided for the magnetic drive and for the heating apparatus 15.

(11) The display apparatus 23 is configured to light continuously with a constant brightness and color, in particular red, on a switching on of the heating apparatus 15 and for the duration of the switched on state of the heating apparatus 15. A switched off state of the heating apparatus 15 can furthermore generally be indicated by the display apparatus 23 in that it does not light up. A distinction can at least be made in this manner with reference to the display apparatus 23 whether the switched on heating state or the switched off heating state 15 is present.

(12) In addition, the display apparatus 23 is, however, also configured to display a respective temperature state of the placement surface at least when the heating apparatus 15 is switched off. For if the heating apparatus 15 has heated the placement surface 17 and is then switched off, the placement surface 17 can have a residual heat that only gradually drops. To warn of this residual heat as required to avoid any painful touching of the still hot placement surface 17, the display apparatus 23 can control the illumination element 25 to transmit light with an illumination characteristic different from said constant illumination for at least so long as the placement surface 17 has an unpleasantly high temperature.

(13) In this respect, a high residual heat, that is a respective temperature of the placement surface 17 in a high temperature range, for example above 100° C., can in particular be signaled by an illumination of the illumination surface of the display apparatus 23 flashing at a high frequency, for example approximately 5 Hz. A reduction of the temperature over time can further be indicated in that the flashing frequency drops correspondingly continuously or in steps. The flashing frequency can, for example, amount to 4 Hz for temperatures between 80° C. and 100° C., to 3 Hz for temperatures between 60° C. and 80° C., to 2 Hz for temperatures between 50° C. and 60° C., to 1 Hz for temperatures between 40° C. and 50° C., and to 0.5 Hz for temperatures between 30° C. and 40° C. Different comparable associations of the flashing frequencies with temperature ranges can, however, also be present.

(14) To detect the respective temperature of the placement surface 17, the magnetic stirrer 11 has a temperature sensor in the region of the heating apparatus 15, said temperature sensor being arranged directly beneath the placement surface 17 and therefore not being visible. The display apparatus 23 can determine the presence of a respective one of a plurality of predefined temperature states of the placement surface 17 with reference to temperature signals that the temperature sensor generates and outputs in dependence on the respective temperature of the placement surface 17 and can then display this respective temperature state in accordance with an illumination characteristic associated therewith.

(15) In addition to and in parallel with the reduction of the flashing frequency, the color of the light transmitted by the multi-color LEDs additionally changes from red over orange to yellow. Provision can furthermore generally be made that the illumination element 25 transmits green light for a predefined time period, for example for 10 s, before it is fully extinguished after falling below a specific temperature, e.g. for instance 30° C. The at least substantially complete cooling of the placement surface 17 can hereby be separately signaled.

(16) Whether the heating apparatus 15 is actually switched on or switched off and whether, in the latter case, the placement surface 17 still has a dangerously or unpleasantly high residual heat or has already cooled so much that a user can touch it without injury can be seen directly from the magnetic stirrer 11 by means of the different illumination characteristics transmitted by the display apparatus 23.

REFERENCE NUMERAL LIST

(17) 11 magnetic stirrer 13 base unit 15 heating apparatus 17 placement surface 19 operating surface 21 actuation element 23 display apparatus 25 illumination element