EP3439775A1

EP3439775A1 - Magnetic stirrer

Info

Publication number: EP3439775A1
Application number: EP17721358.4A
Authority: EP
Inventors: Roman DIL; Sergiy Rubinshteyn; Michael MOSKALENKO
Original assignee: Hans Heidolph GmbH and Co KG
Current assignee: Hans Heidolph GmbH and Co KG
Priority date: 2016-05-11
Filing date: 2017-05-02
Publication date: 2019-02-13
Anticipated expiration: 2037-05-02
Also published as: WO2017194342A1; ES2962276T3; EP3439775B1; EP3439775C0; US20190134582A1; US10967344B2; DE102016108749A1

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.

Description

magnetic

The present invention relates to a magnetic stirrer with a magnetic drive and a footprint for a laboratory vessel with a substance to be stirred.

Such a magnetic stirrer is a typical laboratory device and serves to stir respective substances in a wide variety of laboratory applications. Since, in particular, in the context of laboratory applications in the substances to be stirred on the one hand can be aggressive, such as corrosive or corrosive substances that could damage components of the stirrer, or on the other hand can act on substances that in turn can be sensitive to foreign substances or from For another reason, to protect against contamination, it is advantageous if there is a possibility, as it were, to separate the place of stirring from the stirrer, in particular to provide it outside the stirrer.

For this purpose, the magnetic drive of the magnetic stirrer is designed to generate a magnetic field changing in such a way that a magnetic stirring element, which can be placed directly in the laboratory vessel with the substance to be stirred, can be driven into a stirring motion in order to supply the substance stir. Since the substance is taken up in the laboratory vessel, which comprises material such as glass or plastic, direct contact of the substance with the stirrer can be avoided. Only the separate from the stirrer magnetic stirring element, which is designed in particular as a magnetic rod with a protective coating, which is preferably particularly inert and comprises, for example, polytetrafluoroethylene, (so-called stir bar) is direct introduced into the substance to be stirred and can then be driven by the magnetic field generated by the magnetic drive across the outer wall of the laboratory vessel to a stirring motion. In this way, only a respective easily exchanged and in particular easy to clean magnetic stirring element comes into direct contact with the respective substance, so that neither the magnetic stirrer is exposed to the respective substance nor can contaminate the respective substance by contact with the magnetic stirrer.

The magnetic drive is preferably adjustable, i. at least on and off. Preferably, however, the magnetic drive can also be adjusted beyond. In particular, the magnetic drive can also be adjustable with regard to the speed of the changing magnetic field and thus to the speed of the resulting stirring movement of the magnetic stirring element.

Many laboratory applications involve heating a particular substance as a process step. This is to be understood as meaning any specific type of heat supply which can serve, for example, for heating, heating, thawing or boiling the respective substance. For such a purpose, a respective laboratory device may comprise a heating device. In particular, in order to achieve a uniform heating of the substance over its entire volume or also to simultaneously eliminate inhomogeneities of the substance by mixing, it may be advantageous to stir the substance during heating. Therefore, a magnetic stirrer may further comprise a, in particular adjustable, heating device, which is designed to heat the installation surface in order to heat the substance arranged on the installation surface. The magnetic drive and the heating device of the magnetic stirrer are preferably adjustable separately from one another, wherein the adjustability of the heating device, like the adjustability of the magnetic drive, can basically be limited to the possibility of switching the heating device on and off. Thus, a substance arranged on the footprint can optionally be stirred, heated or at the same time stirred and heated. Preferably, the heater is variably adjustable beyond the mere switching on and off. For example, a heating power of the heater may be adjustable. The adjustability of the magnetic drive and / or the heating device can be limited to a respective range of values, wherein the adjustment can each comprise a continuous and / or stepped adjustment.

The footprint of the magnetic drive is that portion of the magnetic stirrer on which a respective substance for stirring and / or heating is arranged. For this purpose, the footprint is preferably oriented horizontally, so that the substance, in particular a substance containing the laboratory vessel, can be easily placed on the footprint. On the one hand, the magnetic driving of the respective magnetic stirring element can essentially take place through the mounting surface. On the other hand, the heating of the substance can take place in that the installation surface, which is heated by the heating device, transfers heat, in particular via the laboratory vessel, to the substance.

When heated, the footprint can be so warm and possibly so hot that touching the footprint can cause pain or burns. The footprint itself can not be considered in the rule, which temperature it currently has. Especially in a laboratory device, such as a magnetic stirrer, which is not used exclusively for heating, but often just without heating function only in the context of its basic funcionality, so for example for stirring, is used, there is the Risk of painful burning if, for example, a user does not expect that a surface of the laboratory device might be hot. This risk is exacerbated by the fact that the surface may remain hot for some time after the substance has been heated and then removed, even if the heater is already turned off, so that a subsequent user has no apparent cause beware of a potentially hot surface.

It is an object of the invention to reduce the risk of burns in a Mag- stirrer with heating function.

The object is achieved by a Mag netrührer with the features of claim 1 and in particular by the fact that the magnetic stirrer comprises a display device which is adapted to indicate a respective temperature state of the footprint.

On the basis of the display device can thus be visually recognized, which is present for a temperature state of the footprint. In particular, at least two temperature states of the footprint are to be distinguished. The two states are, in particular, a hot state in which the footprint has a temperature in a region in which contact with the footprint should be avoided, since the contact, for example, may be unpleasant, painful or even harmful to health , And a cooling state in which the footprint has a temperature in a range in which touching the footprint is not critical.

In particular, the respective temperature ranges of the temperature states differentiated by the display device can connect seamlessly to one another and be separated in each case by a predetermined or predefinable temperature threshold value. In this way, the footprint of the magnetic stirrer for each temperature a respective temperature state are assigned, which can then be identified by the display device. Depending on the number of different temperature conditions, it is possible to refer to the respective temperature of the installation surface at different levels of fineness.

A displayed temperature state is in particular correlated with the temperature of the installation surface, but in principle regardless of a heating state of the heater. Because the display device should advantageously be able to warn of the actual risk of burning and in particular even if the heater is already off. Conversely, it can be advantageous if the display device can also detect how long the set-up surface can still be touched when the heating device is already being heated. According to an advantageous embodiment, the display device is further configured to indicate a respective heating state of the heating device. In order to display a respective heating state, that is to say in particular to indicate whether the heating device is switched on and the installation surface is currently actively heating or is switched off, the magnetic stirrer could in principle comprise a further display device. Advantageously, however, a respective temperature state of the installation surface and a respective heating state of the heating device are indicated by the same display device. Thus, the display device can be designed to be particularly compact and fewer components are required for the magnetic stirrer.

The display device can in principle spatially and / or temporally separate from each other indicate respective temperature conditions of the footprint and respective heating conditions of the heater. However, the display of respective temperature states and respective heating states preferably takes place in combination, that is, in particular spatially and temporally at least overlapping. For example, different Dene combinations of a respective temperature state and a respective heating state by different optical signals are displayed, so that in each case from a single signal can be deduced both on the respective temperature state of the footprint and on the respective heating state of the Heizvorrich- device.

Since the temperature state of the installation surface and the heating state of the heating device can change over time, the currently present temperature state and the current state of heating are referred to as the "respective" temperature state or the "respective" heating state.

Displaying a respective temperature state can be done in basically many different ways. For example, different states may be represented by different symbols, one or more of which may each be displayed by the display device. For this purpose, the display device may for example comprise a screen-like display panel, such as an LCD or TFT screen. A hot state may e.g. be represented by a warning symbol. It is also conceivable that different temperature states are represented according to their respective temperature range by incremental symbols, such as a different number of bars or bars of different lengths.

However, it is advantageous if the display device has a low complexity in order to be perceived as quickly and clearly as possible. In this context, it is preferred if the display device comprises a light element which can be activated to emit light and is designed to control the light element for emitting light, each having a different light characteristic, for displaying different temperature states of the installation surface and / or different heating states of the heating device. Several different temperature conditions and possibly several different heating states can be displayed by emitting a specific light characteristic by the same light emitting element.

The lighting element may be, for example, a signal light, such as a small lamp. The luminous element may also comprise a luminous surface, which may in particular be backlit by a light source. Such a luminous area may then have a shape that may be selected for good visibility and / or pleasing design. In particular, a symbol can also be represented by the shape of a luminous surface of the luminous element, for example by the luminous surface being shaped in the manner of a warning triangle and / or flickering flames for warning against a hot surface.

As a light source of the light element different bulbs come into question. Preferably, at least one LED is provided due to the low power requirement and the low heat radiation. However, the light-emitting element can in particular also comprise a different type of electroluminescent element as the light source. In this embodiment, preferably several different respective temperature states of the footprint can be displayed by the same light-emitting element, so that the temperature states can not be distinguished on the basis of different light-emitting elements. Instead, however, they can be identified by means of various luminous characteristics emitted by the luminous element. In this case, a light-emitting characteristic is a type of emission of light by the light-emitting element that is specific for a respective state. Respective luminous characteristics for displaying different temperature states of the installation surface may differ in particular with regard to the respective duration, pulse frequency, pulse duration, pulse pause duration, pulse sequence, spatial expansion, color and / or brightness of the emitted light. For example, a temperature state corresponding to a high temperature may be indicated by brighter light than a temperature state corresponding to a lower temperature. Similarly, a temperature state can be indicated by a respectively specific color of the emitted light, wherein, for example, a progression from green via yellow and orange to red can correspond to ever higher temperatures of the set-up surface and vice versa. The light does not need to be emitted continuously, but can be pulsed differently depending on the state to be displayed. As a result, it is fundamentally possible to code a multiplicity of different states by means of a different pulse sequence, for example in the manner of Morse codes.

However, in order to easily identify each state indicated, temporal patterns of low complexity are preferable. In particular, a simple, in particular at least substantially linear, relationship between the pulse frequency, the pulse duration (duration of a single pulse) and / or the pulse pause duration (duration of the period between two pulses) and a mean temperature of the respective temperature state of the footprint exist.

The pulsed or pulsed emission of light is to be understood as a regular increase and decrease in the intensity of the emitted light. In particular, the intensity drops to zero between two pulses. The transition between maximum and minimum intensity can be abrupt in the manner of a step function (which may then correspond to blinking) or continuously, for example in the manner of a triangular, sawtooth or sine function.

According to an advantageous development, the display device is designed to display the on state of the heating device To activate lighting element to emit light in accordance with a first light characteristic, in particular constant light emitting; for combined display of an off state of the heater and a hot state of the footprint to drive the light emitting element to emit light according to a second light characteristic, in particular pulsating light; and / or for combined display of an off state of the heater and a cooling state of the footprint to drive the light emitting element to emit light according to a third light characteristic, in particular no light. In this embodiment, therefore, a combined display of the respective temperature state of the footprint and the respective heating state of the heater takes place. On the basis of the respective mutually different luminous characteristics can be distinguished in particular whether the heater assumes the on state in which light is emitted according to the first luminous characteristic, or the off state. If the heating device assumes the switched-off state, it is possible to further distinguish between at least one hot state and one cold state of the set-up surface on the basis of respective further lighting characteristics. It can be provided that, as long as the switched-state of the heater is present, the heater is thus turned on, the respective temperature state of the footprint is not displayed. Rather, the luminous element can shine continuously and independently of the respective temperature conditions of the installation surface in accordance with the first luminous characteristic.

The first luminous characteristic preferably comprises that the luminous element illuminates constantly, ie at constant intensity unpulsed in one color, for example red. As a result, it is clear in a simple manner that heating is in progress and contact with the installation surface should therefore be avoided. Unlike a simple function display of the heating device, which lights up during heating and completely extinguished when switching off the heater, however, the light emitting element in this embodiment emits light even when the heating device is switched off and thus assumes its switched-off state. This further emission of light takes place as long as the footprint still assumes the hot state, ie a state in which the footprint is still so hot that they should not be touched. However, to make it clear that the installation surface radiates only its residual heat, but is no longer actively heated, the luminous element now emits light with a changed luminous characteristic, namely according to the second luminous characteristic.

The second luminous characteristic preferably comprises pulsating light. In this case, since the intensity of the emitted light is not constant, but regularly increases and decreases again, this luminous characteristic is easily distinguishable from the first luminous characteristic of the switched-on heating state.

Only when the footprint assumes the cooling state, that is, in particular cooled below a predetermined temperature threshold below which a touch of the footprint is unproblematic, the light is emitted according to a third light characteristic. As a result of this luminous characteristic, according to which the luminous element preferably emits no light, the cooling state of the set-up surface and the switched-off state of the heating element are thus simultaneously displayed. In principle, further luminous characteristics may be provided for identifying further states. For example, it may be advantageous to differentiate between at least one hot state and one cooling state of the set-up surface even when the heating device is switched on by different lighting characteristics. Further, more than one hot state of the footprint may be distinguishable by changing each hot state to another Light characteristic is assigned. A gradual change in the tempering state of the installation surface is then preferably indicated by a comparably gradual change in the emitted luminous characteristic, so that the change can be detected particularly intuitively.

According to a further advantageous refinement, the display device is designed to trigger the lighting element to emit pulsating light of different pulse frequency for the combined display of an off state of the heating device and different hot states of the set-up surface. The pulse frequency of the emitted light thus depends on the respective hot state of the footprint. In particular, hot conditions corresponding to hotter temperatures may have a higher pulse rate than hot conditions corresponding to lower temperatures. As a result, an intuitive detection of the respective temperature state of the footprint is made possible. In addition, faster pulse frequencies are usually perceived easier and faster, so that the perception of the display device is advantageously the easier, the higher the temperature of the footprint and thus the threat to a user. Depending on the number of different hot states of the set-up surface, the temperature of the set-up surface can in principle be made recognizable in any desired finely graduated manner.

In the embodiments described above, the respective

Luminous characteristics for further clarification of respective states of Magnirrers still additionally, in particular as colored, be differentiated, so that for example in the on state of the heater and in the hottest of the hot conditions of the footprint of the light emitting element emits red light and the color with decreasing pulse rate, by a change in temperature is signaled, changed from red to orange to yellow. According to a further advantageous embodiment, the magnetic stirrer comprises an actuating element, in particular for switching and / or adjusting the heating device, wherein the display device is provided on the actuating element. In particular, the display device may comprise the actuating element comprising or integrated into the actuating element. Such an actuator can only serve to switch the heater, so be functionally limited to turn the heater on or off. However, the actuating element can also serve to adjust the heating device moreover, ie to set a heating power of the heating device. The actuating element, which as a rule is to be actuated manually, can be, for example, a toggle switch, pushbutton, rotary knob or the like, wherein such actuating elements can also be realized by touch-sensitive, in particular capacitive, input elements, such as touch elements can be modeled. Since the actuating element is designed at least for switching the heating device on and off, preferably also for further adjustment of the heating device, a spatially direct visual feedback of the respective adjustment can be achieved by providing the display device on the actuating element. For this purpose, the actuating element may be surrounded on several sides by the display device, in particular by a luminous surface or the aforementioned luminous element of the display device, wherein the display device does not necessarily have to surround the actuating element in its entirety. Alternatively or additionally, the display device can be integrated into the actuating element, for example by the actuating element being designed to be transparent at least in regions, and this area being backlit, so that the area functions as a luminous area of the display device.

According to a further embodiment, the magnetic stirrer comprises a temperature sensor for detecting a respective temperature of the installation surface, wherein the display device is designed to determine and display the respective temperature state of the installation surface as a function of the respective temperature detected by the temperature sensor. As a temperature sensor, for example, a simple platinum measuring resistor can be used. Preferably, the temperature sensor generates a signal representing the respective temperature of the footprint and is received by the display device or a control device of the display device. There, the respective temperature state of the footprint can then be determined by selecting a respective one based on the signal from predefined temperature states. Subsequently, this temperature state can then be displayed, for example by the lighting element being driven to emit a respective luminous characteristic associated with this temperature state.

According to a further embodiment, the magnetic stirrer comprises a base unit with a common power supply for the magnetic drive, for the heating device and for the display unit, wherein the heating device, in particular a heating plate, is formed separately from the base unit and arranged on the base unit and has the set-up surface , Preferably, the display device is then provided on the base unit.

In particular, said actuating element may be provided on the base unit and the display device may then be provided on the actuating element, as explained above. In principle, it is also possible to provide the display device directly on the heating device, so that the temperature state of the installation surface can advantageously be displayed close to or even in the installation surface itself. In contrast, the arrangement of the display device on or in the base unit has the advantage that it can be supplied with electricity there more easily and the heat generated by the heater is exposed to at least a lesser extent. A magnetic stirrer according to the invention offers greater safety against accidental burns than conventional magnetic stirrers with a heating function by means of a simple, optionally also retrofittable display device. This display device allows a user of the magnetic stirrer, in a quick and intuitive way to detect whether the footprint of a previous heating still has residual heat, so that contact with the footprint should be avoided. In principle, such a residual heat display according to the invention can also be provided with comparable advantages as with a magnetic stirrer in the case of other typical laboratory devices which, in addition to a basic functionality, also have an additional heating function.

The invention will now be described by way of example only with reference to the figure. Fig. 1 shows an embodiment of a magnetic stirrer according to the invention in a highly simplified schematic representation.

As an example of a laboratory device with a residual heat display according to the invention, a magnetic stirrer 11 is shown in greatly simplified form in FIG. The magnetic stirrer 1 1 comprises a base unit 13, which is designed as a flat cuboid with a bevelled front upper edge. At the top of the base unit 13, a heater 15 is arranged, which has a flat cylindrical shape. The upwardly facing end portion of this form is designed as a heating plate that can be heated. At the same time, the end face of the cylindrical shape forms a footprint 17 of the magnetic stirrer 1 1.

On the footprint 17, which is horizontally aligned with its bottom on a flat surface, such as a table top, with the usual arrangement of the magnetic stirrer 1 1, a laboratory vessel with a substance to be stirred and / or to be heated can be provided. To stir the substance, a magnetic beautiful stirring element introduced about in the manner of a so-called stir bar in the substance, which can be driven through the bottom of the laboratory vessel to a stirring motion. In the interior of the magnetic stirrer 1 1, a magnetic drive not visible from the outside is provided for this purpose. The latter is designed to generate a magnetic field in a region adjoining the mounting surface above the mounting surface, which magnetic field can then exert magnetic forces on the magnetic stirring element such that the magnetic stirring element rotates at least substantially around the cylinder axis of the cylinder shape of the heating device 15. In this way, by the magnetic drive provided in the interior of the magnetic stirrer 1 1, a stirring movement of the magnetic stirring element can be induced in the midst of the substance to be stirred. The heating device 15, which may extend at least partially into the interior of the magnetic stirrer 1 1, comprises at least one electrical heating element which is in thermal contact with the mounting surface 17. In this way, the heating device 15 can heat the footprint 17 so that heat can then be transferred from the footprint 17 to the respective substance placed on the footprint 17 in order to heat the substance. So that the footprint 17 is heated as homogeneously as possible, at least the said end face of the cylindrical shape of the heating device 15 comprises a material with high thermal conductivity, in particular a metal. In order to avoid that heat is transferred from the footprint 17 to the base unit 13, a gap may be provided between a lower edge of the lateral surface of the cylindrical shape and the upper side of the base unit 13.

The magnetic drive and the heater 15 are powered by a common power supply, which is integrated in the base unit and has a terminal for connecting a power plug. The magnetic drive and the Heizvornchtung 15 are at least insofar adjustable as they can be switched on and off independently in principle, to selectively stir the respective substance and / or to heat. Said bevel of the front upper edge of the cuboid shape of the base unit 13 forms an operating surface 19 of the magnetic stirrer 1 1, on which a plurality of actuating elements 21 for adjusting the magnetic stirrer 1 1 are arranged. The actuating elements 21 serve, in particular, to switch the magnetic drive on and off and to set a speed of change of the magnetic field in order thereby to set the speed of the stirring movement or to switch the heating device 15 on and off and to set a heating power of the heating device 15 to adjust the speed of heating. Of these actuators 21 only one is shown, which is designed as a flat push button or as a touch element and by the operation of the heater 15 can be switched on and off alternately. On the push button 21, a display device 23 of the magnetic stirrer 1 1 is provided, which comprises a light-transmitting luminous surface as a luminous element 25, which is backlit by a light source in the form of multi-colored LEDs. This luminous area surrounds the at least substantially round push-button 21 annular. The supply of the display device 23 with power via the same power supply, which is also provided for the magnetic drive and the heater 15.

The display device 23 is designed to light up when the heating device 15 is switched on and for the duration of the switched-on state of the heating device 15 continuously with constant brightness and color, in particular red. Further, a turned-off state of the heater 15 may be displayed by the display device 23 basically by not lighting. In this way it can at least be distinguished on the basis of the display device 23 whether the switched on or off heating state of the heating device 15 is present. In addition, however, the display device 23 is also designed to indicate a respective temperature state of the installation surface in any case when the heating device 15 is switched off. Because when the heater 15 has heated the footprint 17 and then turned off, the footprint 17 may have a residual heat, which only gradually decreases. In order to warn against this residual heat to avoid a painful touch of the still hot footprint 17, the display device 23, the light emitting element 25 to drive light with a deviating from said constant lighting luminous characteristic at least as long as the footprint 17 is an unpleasantly high Temperature has.

In this case, a high residual heat, ie a respective temperature of the footprint 17 in a high temperature range, for example above 100 ° C, in particular by high frequency, for example, about 5 Hz, flashing lights of the illuminated surface of the display device 23 is signaled. A decrease of the temperature over time can also be indicated by the fact that the flashing frequency decreases continuously or stepwise accordingly. For example, the flashing frequency for temperatures between 80 ° C and 100 ° C 4 Hz, for temperatures between 60 ° C and 80 ° C 3 Hz, for temperatures between 50 ° C and 60 ° C 2 Hz, for temperatures between 40 ° C and 50 ° C 1 Hz and for temperatures between 30 ° C and 40 ° C 0.5 Hz. However, other comparable assignments of flash frequencies to temperature ranges may also be present.

For detecting the respective temperature of the installation surface 17, the magnetic stirrer 1 1 in the region of the heating device 15 has a temperature sensor which is arranged directly below the installation surface 17 and is therefore not visible. On the basis of temperature signals which the temperature sensor generates and outputs in dependence on the respective temperature of the installation surface 17, the display device 23 can detect the presence of a respective one of a plurality of predefined temperature states of the installation surface 17 and then display this respective temperature state in accordance with a luminous characteristic assigned to it.

In addition and in parallel with the decrease in the flashing frequency, the color of the light emitted by the multicolored LEDs also changes from red to orange to yellow. Furthermore, it can generally be provided that the lighting element 25 falls below a certain temperature, e.g. about 30 ° C, emits green light for a defined period of time, for example 10 s before it goes out completely. In this way, the at least substantially complete cooling of the footprint 17 can be signaled separately.

Based on the various emitted by the display device 23

Luminous characteristics can be directly considered the magnetic stirrer 1 1, whether at any time, the heater 15 is just turned on or off and whether in the latter case, the footprint 17 still has a dangerous or unpleasant high residual heat or has already cooled so much that a user she can touch without damage.

LIST OF REFERENCES

1 1 magnetic stirrer

13 Base unit 15 Heating unit

17 footprint

19 control surface

21 actuator label

23 Display device 25 lighting element

Claims

claims

Magnetic stirrer (1 1) with a Magnetantneb and a mounting surface (17) for a laboratory vessel with a substance to be stirred,

wherein the magnetic drive is adapted to generate a magnetic field changing in such a way that a magnetic stirring element in the laboratory vessel can be driven into a stirring motion in order to stir the substance,

wherein the magnetic stirrer (11) further comprises a heater (15) adapted to heat the footprint (17) to heat the substance,

characterized,

in that the magnetic stirrer (1 1) comprises a display device (23) which is designed to display a respective temperature state of the set-up surface (17).

Magnetic stirrer according to claim 1,

characterized,

the display device (23) is further configured to indicate a respective heating state of the heating device (15).

Magnetic stirrer according to claim 1 or 2,

characterized,

the display device (23) comprises a light element (25) which can be activated to emit light, wherein the display device (23) is designed to control the light element (25) for emitting light, each having a different light characteristic, for displaying different temperature states of the installation surface (17) and / or different heating states of the heating device (15).

Magnetic stirrer according to claim 3,

characterized,

in that the display device (23) is designed, for indicating an activated state of the heating device (15), to actuate the luminous element (25) to emit light in accordance with a first luminous characteristic, in particular constant luminous light; for combined display of an off state of the heating device (15) and a hot state of the footprint (17), the lighting element (25) to drive light according to a second light characteristic, in particular pulsating light to emit; and / or for the combined display of an off state of the heating device (15) and a cooling state of the mounting surface (17), the lighting element (25) to drive to emit light according to a third light characteristic, in particular no light.

Magnetic stirrer according to claim 3 or 4,

characterized,

in that the display device (23) is designed to trigger the lighting element (25) to emit pulsating light of different pulse frequency for the combined display of an off state of the heating device (15) and different hot states of the setting surface (17). Magnetic stirrer according to at least one of claims 3 to 5,

characterized,

in that respective luminous characteristics for indicating different temperature states of the installation surface (17) differ with regard to the pulse frequency, the color and / or the brightness of the light respectively emitted by the luminous element (25).

Magnetic stirrer according to at least one of the preceding claims, characterized

in that the magnetic stirrer (11) comprises an actuating element (21), in particular for switching and / or adjusting the heating device (15), the indicating device (23) being provided on the actuating element (21), in particular comprising the actuating element (21) arranged or integrated in the actuating element (21).

the magnetic stirrer (1 1) comprises a temperature sensor for detecting a respective temperature of the installation surface (17),

wherein the display device (23) is adapted to the respective

Determine the temperature state of the footprint (17) as a function of the temperature detected by the respective temperature and display.

in that the magnetic stirrer (1 1) comprises a base unit (13) with a power supply for the magnetic drive, the heating device (15) and the display unit (23),

wherein the heating device (15), in particular a heating plate, separate from the base unit (13) is formed and arranged on the base unit (13) and has the installation surface (17),

and wherein the display device (23) is provided on the base unit (13).