Adaptive dirt detection in a vacuum cleaner

Abstract

Vacuum cleaner (2) for vacuuming dirt (4) from a surface (6),- with a dirt sensor (26) configured to determine a dirt value (WS) indicating the amount of dirt (4) currently being vacuumed,- with a floor sensor (28) configured to determine a hardness level (GH) indicating the hardness of the surface (6) currently being vacuumed,- with a display module (30),- with a control module (32) which has at least one automatic mode (MA) as its mode (M) and is configured in this mode to:- for a hardness level (GH) below a soft floor threshold (GW):- output the dirt value (WS) on the display module (30),- and otherwise,- in addition to the dirt value (WS), determine a reduction value (WR) in the form of the dirt value (WS) weighted with a weighting value (WG) less than one and output it on the display module (30).

Description

The invention relates to a vacuum cleaner with a dirt sensor for dirt detection. From DE 689 13 166 T2, a vacuum cleaner is known which comprises: a dust sensor means for detecting dust in air drawn in through an intake passage of the vacuum cleaner in order to generate a dust signal that is indicative of the result of the detection, and which further comprises: an adjustment means for adjusting the sensitivity of the dust sensor means for dust detection in accordance with the control signal; and a differentiation means for detecting the type of object to be cleaned by the vacuum cleaner and for generating a differentiation signal that is indicative of the type of object, wherein the differentiation signal is supplied to the adjustment means in use as the control signal in order to adjust the sensitivity of the dust sensor means. From DE 10 2007 061 146 A1, a method is known for evaluating a particle signal using an evaluation unit assigned to a control device. In this method, the particle signal is generated by a sensor within a flow element and is at least dependent on the number of particles in a two-phase flow generated during the cleaning of a surface by means of a suction device connected to the flow element. The evaluation unit derives a control signal from the particle signal for further control of an actuator influenced by the control device. In order to reliably consider factors influencing the presence of dust in addition to the amount of dust, the evaluation unit takes into account at least one parameter dependent on the probability of the presence of particles in the two-phase flow when determining the control signal, in addition to the particle signal. From DE 10 2015 100 483 A1, a suction unit is known for a vacuum cleaner, in particular a floor vacuum cleaner or a handheld vacuum cleaner, comprising a housing, a brush arrangement and a motor for driving the brush arrangement, which solves the technical problem of further improving the known suction unit by providing a power sensing device for detecting the electrical power consumed by the motor of the brush arrangement and by generating an output signal that depends on the power consumption of the motor. The object of the present invention is to specify improvements relating to a vacuum cleaner with a dirt sensor. The problem is solved by a vacuum cleaner according to claim 1. Preferred or advantageous embodiments of the invention and of other invention categories will become apparent from the further claims, the following description and the accompanying figures. The vacuum cleaner is designed to, or is intended to, vacuum up dirt from a surface during operation. The term "vacuum cleaner" is used broadly here and includes all such cleaning devices, in particular household vacuum cleaners, upright or handheld vacuum cleaners, or robotic vacuum cleaners. The vacuum cleaner contains a dirt sensor, also known as a "dirt detection sensor." This sensor is designed to determine a dirt level during operation. The dirt level indicates the amount of dirt currently being vacuumed up. Such a dirt sensor typically contains a light barrier with a light source and sensor; the dirt level is the amount of light reaching the sensor. The amount of light is reduced by the dirt particles being vacuumed up. The more the light is reduced, the more dirt is being vacuumed up. The vacuum cleaner contains a floor sensor. This sensor is designed to determine the hardness level during operation. The hardness level indicates the hardness of the surface currently being vacuumed. A hard floor has a lower hardness level (e.g., "0" for a tile floor) than a soft floor (e.g., "2" for a carpet). "Hardness" here refers specifically to a qualitative value, such as a floor class. One such floor class is, for example, "hard or smooth floor" (wood / parquet / laminate / PVC / tiles / stone / concrete / glass / ...). Another floor class is, for example, a soft floor or carpet, pile, fiber, or woven floor. For the purposes of this discussion, it is assumed that a smooth or hard floor has a hardness value from zero up to a soft floor threshold (e.g., "1"). Other types of flooring, or soft floors, have hardness levels above the soft floor threshold. The soft soil limit can be predefined and adjusted to the soil sensor or the degree of hardness and can be determined, for example, through empirical tests in order to differentiate the desired soil classes. The vacuum cleaner contains a display module. Various information can be shown to a potential user of the vacuum cleaner on this module. The display module includes, for example, lights, a text display, etc. The vacuum cleaner contains a control module. The control module, and therefore the vacuum cleaner, has at least one operating mode, namely an automatic mode. If there are multiple modes, the vacuum cleaner can be switched between them. The control module, or rather the vacuum cleaner, operates within these modes. When operating in automatic mode, the control module is configured to proceed as follows: It uses the currently detected floor hardness level. For a floor hardness level determined by the floor sensor that is below the soft floor threshold, the control module displays the dirt level on the display module. In other words, this applies when vacuuming hard floors. The control module is configured to proceed as follows in other cases. "Otherwise" means that the hardness level is above the soft floor threshold, i.e., a soft floor, not a hard floor, is detected or is currently being vacuumed. In this case, the control module calculates a reduction value. This is determined by weighting (specifically multiplying) the dirt level by a weighting value. The weighting value is less than one. The control module then displays the reduction value on the display module instead of the dirt level. This process is therefore executed when a soft floor is currently being vacuumed. The weighting value is chosen specifically as follows: It is based on a certain amount of dirt, or a corresponding dirt value, that still accumulates when vacuuming a sufficiently cleaned soft floor of a certain hardness. This dirt value (the value displayed to the user) would correspond to an insufficiently cleaned hard floor when vacuuming a hard floor. If the user were to actually see this dirt value when vacuuming a soft floor, they could assume—assuming optimal cleaning of a hard floor—that the soft floor is not yet sufficiently clean. This should be avoided, however, to prevent over-cleaning the soft floor and thus causing excessive wear and tear, as the soft floor is already sufficiently clean even at this dirt value.Therefore, the weighting value is chosen so that the dirt value is reduced to a reduction value that corresponds to a dirt value of a sufficiently cleaned hard floor. Thus, even when vacuuming soft floors, the user sees a lower "dirt value" (in the form of a reduction value). The system interprets this value as indicating that the soft floor now appears sufficiently clean and can, or will, therefore stop vacuuming the soft floor. In other words, the user is shown a simulated lower amount of dirt currently being vacuumed. In other words, "less dirt" or a "cleaner surface" is simulated on a soft floor. Applied to the dirt sensor, this means that its sensitivity, intensity, or sensitivity—starting from that of a hard floor—is reduced or adapted to the soft floor. As a result, the vacuum cleaner displays a reduced level of dirt, indicating to the user that the soft floor is less dirty or better cleaned, rather than a general dirt level. Consequently, this usually leads to the user finishing vacuuming the soft floor sooner, thus protecting the floor. Optionally, the dirt level and reduction value can also be displayed simultaneously. Additional data, such as soil class, hardness level, etc., can also be shown on the display module. In a preferred embodiment, the control module is configured to select the currently used weighting value depending on the currently determined hardness level. Specifically, the higher the hardness level, the softer the corresponding floor, for example, the higher the pile height of a carpet, the lower the weighting value. In other words, the softer the surface, the more the actual dirt value is reduced. As a result, less dirt, or an even cleaner surface, is simulated as the hardness level increases, i.e., as the floor becomes softer.This means that particularly soft floors, such as high-pile carpets, appear cleaned more quickly and are thus better protected. Short-pile carpets, which are generally more resilient, may appear dirty for longer and therefore require longer vacuuming, resulting in a more thorough cleaning. The harder (lower the hardness rating) a vacuumed surface is, the more realistically its level of soiling is displayed. In a preferred embodiment, the control module is configured as follows: If the dirt level exceeds a dirt threshold, the following procedure is performed: the cleaning power of the vacuum cleaner is increased from an initial value for a predefined period. Alternatively, the same procedure can be used when a dirt threshold is exceeded, based on the reduction value (instead of the dirt level). The cleaning power is, in particular, the suction power and / or, if applicable, the power of a cleaning roller of the vacuum cleaner, if one is present (see below). The initial value is the value at which the vacuum cleaner is operated initially or until the aforementioned threshold is exceeded when cleaning the surface.In other words, without user intervention (for example, by adjusting a power control), the vacuum cleaner's cleaning power is increased for a short period of time when the surface is heavily soiled, in order to clean the surface particularly thoroughly. Specifically, the power then returns to its original setting after this period has elapsed. In a preferred embodiment, the vacuum cleaner includes a cleaning roller, specifically the one already mentioned above. This roller is designed to maintain contact with the floor surface, at least when vacuuming soft floors, during operation. The floor sensor is configured to determine the floor hardness based on a current operating value of the cleaning roller. Such an operating value could be, for example, the current draw of a drive motor for the cleaning roller. This design allows for a particularly simple floor sensor. In a preferred embodiment, the control module has at least two modes and is switchable between automatic mode and a real-world mode. The vacuum cleaner thus has at least two operating modes: automatic mode and real-world mode. The real-world mode can also be referred to as "high sensitivity," and the automatic mode as "automatic sensitivity," with regard to the dirt sensor. In real-world mode, the control module is configured to display the dirt level instead of the reduced value on the display module, even for floor hardness levels above (greater than or equal to) the soft floor threshold. Therefore, in this mode, the actual dirt level, and not the reduced value, is always displayed on the display module, even when vacuuming soft floors. In particular, the reduced value is not used internally within the vacuum cleaner or the control module in real-world mode.In this real-world mode, a corresponding weighting or reduction value does not need to be determined at all. For example, in real-world mode, the cleaning performance is controlled solely based on the dirt level (exceeding the dirt threshold) and not on the reduction value. This allows the vacuum cleaner operator to make a truly realistic assessment of the dirt level, even on soft floors. In a preferred embodiment, the display module includes a cleanliness indicator. This indicates when the dirt level falls below a predefined cleanliness threshold. Alternatively, the reduction value can be checked for falling below this threshold, similar to the above. Such a cleanliness indicator is, in particular, a binary indicator, for example, a green LED that only illuminates when the cleanliness threshold is undershot, thus indicating a "clean" or sufficiently cleaned surface. When the corresponding cleanliness indicator illuminates or is activated, the user can therefore stop processing the currently vacuumed section of the surface, as it is now sufficiently clean. In a preferred embodiment, the display module includes an information display. This displays contextual information about the currently selected mode on the vacuum cleaner. Thus, a user of the vacuum cleaner is informed about the current operating mode and its advantages and disadvantages (e.g., protection of carpets / reduction of dirt display) and can therefore use the selected operating mode according to their needs. The object of the invention is also achieved by a method according to claim 8. This method is for operating the vacuum cleaner according to the invention. In this method, the dirt sensor determines the dirt level. The floor sensor determines the hardness. In automatic mode, the control module displays the dirt level on the display module for a hardness level below the soft floor threshold; otherwise, it determines the reduction value and displays this in addition to the dirt level on the display module. The method and at least some of its possible embodiments, as well as the respective advantages, have already been explained in substance in connection with the vacuum cleaner according to the invention. The invention is based on the following findings, observations, and considerations and further comprises the following preferred embodiments. These embodiments are sometimes referred to simply as "the invention." The embodiments may also include parts or combinations of the embodiments mentioned above, correspond to them, and / or may include previously unmentioned embodiments. According to the invention, an adaptive dirt detection sensor is obtained. According to the invention, a method is provided which adapts the intensity of a sensor (dirt sensor) of a cleaning device (vacuum cleaner) depending on the substrate. The invention is based on the following observation: During a dry cleaning process – hereinafter referred to as vacuuming – the dirt collected is transported by most vacuum cleaners on the market into a so-called dust collection container. Manually operated cleaning devices, such as multi-use handheld vacuums, as well as autonomously operating cleaning devices, such as cleaning robots, have such a dust collection container. A typical "transport path" of the dirt during a cleaning process, for example in a multi-use handheld vacuum, is as follows: Dirt is picked up from the surface by a nozzle assembly attached to it. Through a tube, the dirt is conveyed by an airflow / suction flow to a dust separation system. There, the dirt enters a dust box. The airflow is generated by a blower. The dirt on the floor of the surface to be cleaned is captured by a combination of a roller (in the nozzle assembly) rotating around its own axis and an airflow directed inwards into the cleaning device over this roller and transported into the multi-use handheld device. Inside the device, the dirt is first separated from the airflow in the dust collection container (dust box) (via a separation vortex and / or filter surfaces) and then stored in the dust collection container. New cleaning devices also have sensors that are located between the nozzle assembly and the dust separation system and that can measure the amount of dirt collected. If a particularly large amount of dirt is vacuumed up at a point x in the room, the sensor indicates this in a first step, so that in a further step the control of the cleaning device increases the cleaning performance at that very point - e.g. by increasing the fan and / or brush roller speed. The invention is based on the following insight: However, such a general increase in cleaning performance is not useful in all areas of a household. In addition to automatically adjusting the cleaning power, the user can also use the output of the cleaning device's dirt detection sensor to check whether an area has been sufficiently cleaned. Sufficient cleanliness is indicated when few or no dirt particles pass the dirt detection sensor. However, this situation, in which few to no dirt particles pass the sensor, is only possible on high-pile carpets with very intensive cleaning effort; in other words, an unusually large number of double strokes with the cleaning device would have to be performed for the normal consumer. The reason for this lies in the structure of the high-pile carpet: Once dirt is tracked in, it sinks deeper and deeper into the fibers over time – and even a cleaning machine with a rotating brush roller, due to the beating and suction action of the mechanism and blower, rarely manages to remove all particles in one or two double strokes. This is because the carpet should not be damaged during cleaning (e.g., by pulling out carpet fibers). Therefore, a dirt detection sensor used on a high-pile carpet will always detect dirt particles with a small number of double strokes, because especially deeply embedded dirt does not loosen after one or two double strokes. While this circumstance is advantageous for some consumer groups because they have no problems with time-consuming treatment of their carpets due to their cleaning preferences, it is assumed within the framework of the inventive finding that other consumer groups are more likely to be unsettled regarding the information provided by the dirt detection sensor if it detects dirt on high-pile carpets over a longer cleaning period. According to the invention, the following method or vacuum cleaner implementing it is therefore particularly proposed: The invention is based on a dirt detection sensor implemented in a cleaning device. This sensor is shown here as being installed in the tube of a manually operated multi-use handheld device – however, it can also be located elsewhere, for example in the nozzle, the inlet, or just before it enters the dustbin. It can also be integrated into other cleaning devices, such as a cleaning robot. The output of the dirt detection sensor is connected to the control unit (control module) of the cleaning device. Similarly, a floor sensor (e.g., a current sensor that monitors the current supplied to the brush roller) provides data to the control unit. Since, in the example, the power consumption on soft surfaces such as carpets increases due to the nozzle sinking in more deeply and the resulting increase in resistance, current measuring sensors are very suitable for distinguishing between hard and soft floors. In order to meet the needs of different target groups, the following procedure is proposed: The consumer can adjust the sensitivity of the dirt detection sensor (select a mode) via the menu of the cleaning device or via an app. If the sensitivity is set to "High" (real mode), the dirt detection sensor displays the data as measured (dirt level on the display module) - with the consequence that on soft surfaces - especially high-pile carpet - more intensive cleaning, i.e., more double strokes, are required than on hard floors. However, the consumer can be informed about this via an information field (information display), so that he / she is aware of this fact when choosing this setting. The measured values ​​are also used by the control unit of the cleaning device, and as soon as a certain amount of dirt (exceeding the dirt limit) passes the dirt detection sensor, the cleaning performance (e.g., power of the blower and the brush roller) is increased for a predefinable period of time T. If the consumer selects the sensitivity setting "Automatic" (automatic mode), the data from the floor sensor / current measurement sensor will be included in the evaluation in addition to the data from the dirt detection sensor. If the floor sensor / current measurement sensor indicates that the cleaning device is on a hard floor (hardness level below the soft floor limit), the data from the dirt detection sensor will be displayed as measured and used by the control of the cleaning device. Additionally, the power of the blower and the brush roller is increased again for a predefinable period of time T as soon as a certain amount of dirt passes the dirt detection sensor. However, if the floor sensor / current measurement sensor indicates that the cleaning device is on a soft floor such as a carpet (hardness level equal to or above the soft floor limit), the data (dirt value) from the dirt sensor is first weighted (weighting value) before being processed by the control unit (as a reduction value) or displayed to the consumer. The aim of this weighting is to reduce the sensitivity of the dirt detection sensor, especially on high-pile carpets. Subsequently, the power of the blower and the brush roller is increased again for a predefined period T. In another embodiment of the invention, the weighting (weighting value) can be carried out depending on the degree of hardness (value of the current measuring sensor). This enables improved individual modification of the measured value (dirt value). This leads to a reduction in sensitivity in area A of the dirt detection sensor by a factor of A1, while in area B of the dirt detection sensor, a reduction by a factor of B1 is made. Specifically, a short-pile carpet can be cleaned with a different sensitivity than a high-pile carpet, since the current sensor indicates a higher average current draw on the high-pile carpet than on a short-pile carpet (due to the different levels of hardness). In addition to the current sensor, other sensor data (especially from other floor sensors) can also be included in the evaluation, in particular, for example, cameras and sensors that measure the distance traveled or the distance between the cleaning device and objects in the household. Their values ​​can be analyzed and, if necessary, weighted in the same way as described using the example of the current measuring sensor. According to the invention, the following advantages arise: The sensitivity of a dirt detection sensor can be adjusted by the consumer. By fusing the output of the dirt detection sensor with the output of a floor sensor (current measuring sensor), the sensitivity of the dirt detection sensor can be adapted to different surfaces to suit consumer groups. Further features, effects, and advantages of the invention will become apparent from the following description of a preferred embodiment of the invention and the accompanying figures. Figure 1 shows a vacuum cleaner according to the invention, and Figure 2 shows a flowchart for a method according to the invention, each in a schematic diagram. Fig. 1 shows a vacuum cleaner 2 in the form of a multi-use handheld device. In operation, it serves to collect dirt 4 (symbolically represented as particles) from a surface 6 that is currently being vacuumed. The vacuum cleaner 2 includes a nozzle assembly 8, which is connected via a suction tube 10 to a base body 12 of the vacuum cleaner 2. This base body contains a dust separation system 14, a dust box 16, and a blower 18. The nozzle assembly 8 includes a cleaning roller 20, which rotates around a rotary axis 22 during operation and is driven here by an electric motor (not shown) within the nozzle assembly 8. In a dry cleaning process, in this case vacuuming, the dirt 4 is picked up from the surface 6, transported via the nozzle assembly 8 and through the suction tube 10 to the dust collection container in the form of the dust box 16. This occurs through negative pressure or an airflow generated by the blower 18. A transport path 24 for the dirt is indicated by arrows. The cleaning roller 20 rotates around the axis of rotation 22 and is equipped with bristles (not shown), which further loosen the dirt 4 from the surface 4. The vacuum cleaner 2 also contains a dirt sensor 26, which is located in the transport path 24 and is only symbolically indicated here. During operation, the dirt sensor 26 generates a dirt value WS (only symbolically indicated in the figure). The vacuum cleaner 2 also contains a floor sensor 28, which determines the hardness GH of the currently vacuumed surface 6 during operation. The vacuum cleaner 2 contains a display module 30 and a control module 32, which are also only symbolically indicated here. The control module 32, or the vacuum cleaner 2, can be switched between different modes M, here an automatic mode MA and a real-time mode MR, which is also only symbolically indicated in Fig. 1. Fig. 2 shows a flowchart of a method for operating the vacuum cleaner 2 from Fig. 1. First, a user of the vacuum cleaner 2 (not shown) sets the mode M on it, namely either the automatic mode MA or the real mode MR. This is done in step S1. In other words, in step S1 the sensitivity of the dirt detection sensor or dirt sensor 26 is set. In real-world mode MR, the process is as follows: First, in step S2, context information IK is displayed on an information display 36 of the display module 30 and thus shown to the user. The context information IK contains information for the user or consumer regarding the selected mode M, in this case, real-world mode MR. In step S3, the dirt detection sensor 26 is read. The read dirt value WS is then compared with a dirt threshold GS. Higher dirt values ​​WS indicate increased soiling or more dirt 4 currently being vacuumed up. If the dirt threshold GS (indicated by a checkmark in Fig. 2) is exceeded, a large amount of dirt 4 is currently being vacuumed up. In step S8, the cleaning performance LR of the vacuum cleaner 2 is increased for a predefined time period T.This is based on an initial cleaning performance value WA LR, which the vacuum cleaner currently exhibits before the increase, i.e., at which it is normally operated. In other words, the power of the blower 18 and / or the cleaning roller 20 or bristle roller is increased for the predefined time period T. If, on the other hand, no high amount of dirt is detected, i.e., no dirt value WS above the dirt limit value GS (marked by a cross in the figure), the current cleaning performance LR (performance of the blower 18 or the cleaning roller 20) is maintained in step S4. If, however, the user selects automatic mode MA as mode M in step S1, the following steps are performed: First, in step S5, context information IK, here regarding automatic mode MA, is also displayed on the display module 30, thus providing the user with information about the selected automatic mode MA as described above. In step S6, both the dirt detection sensor 26 and the floor sensor 28 are read. These are current sensors used to measure the current consumption of the cleaning roller 20 motor (not shown). Then, it is checked again whether the dirt level WS exceeds the dirt level limit GS. If this is not the case (indicated by a cross), step S7 is performed analogously to step S4 above, and the cleaning performance LR of the vacuum cleaner 2 is maintained. However, if this is the case (as indicated by a "tick" in the figure), the system checks whether a soft floor is detected, i.e., whether the hardness level GH exceeds a soft floor limit value GW. If this is not the case (as indicated by a "cross" in the figure, i.e., detection of a hard floor), the cleaning performance LR is increased for the time period T in step S9, analogous to step S8 above. If, however, this is the case ("tick", i.e., detection of a soft floor), a reduction value WR is calculated in step S10 by multiplying the dirt value WS by a weighting value WG that is less than one. In step S11, the cleaning performance LR is increased over the time period T, analogous to steps S8 and S9 above, but here the reduction value WR is displayed on the display module 30. However, in steps S4, S7, S8 and S9, the dirt value WS and not the reduction value WR is displayed on the display module 30. Figure 1 also symbolically indicates that the vacuum cleaner 2, or rather the display module 30, contains a cleanliness indicator 34, here a green light. This light remains off or displays a color other than green (e.g., red or orange hues) as long as the dirt level WS is above (and including) a cleanliness level WE. When the cleanliness level falls below WE, the cleanliness indicator lights up green. The user thus recognizes, via a binary signal, that the currently vacuumed surface is sufficiently clean, i.e., that a sufficiently low dirt level WS is present or has been reached. This allows the user to proceed with vacuuming another section of the surface 6. Reference symbol list 2 Vacuum cleaner 4 Dirt 6 Surface 8 Nozzle assembly 10 Suction tube 12 Base body 14 Dust separation system 16 Dust box 18 Blower 20 Cleaning roller 22 Rotation axis 24 Conveyor path 26 Dirt sensor 28 Floor sensor 30 Display module 32 Control module 34 Cleanliness indicator 36 Information display GH Hardness level GS Dirt limit GW Soft floor limit IK Context information LR Cleaning performance M Mode MA Automatic mode MR Real mode S1-11 Step T Time span WA Initial value WE Clean value WG Weighting value WS WR Reduction value Dirt value

Claims

Vacuum cleaner (2) for vacuuming dirt (4) from a surface (6),- with a dirt sensor (26) configured to determine a dirt value (WS) indicating the amount of dirt (4) currently being vacuumed,- with a floor sensor (28) configured to determine a hardness level (GH) indicating the hardness of the surface (6) currently being vacuumed,- with a display module (30),- with a control module (32) which has at least one automatic mode (MA) as its mode (M) and is configured in this mode to:- for a hardness level (GH) below a soft floor threshold (GW):- output the dirt value (WS) on the display module (30),- and otherwise,- in addition to the dirt value (WS), determine a reduction value (WR) in the form of the dirt value (WS) weighted with a weighting value (WG) less than one and output it on the display module (30). Vacuum cleaner (2) according to claim 1, characterized in that the control module (32) is configured to select the weighting value (WG) depending on the degree of hardness (GH). Vacuum cleaner (2) according to one of the preceding claims, characterized in that - the control module (32) is configured to increase the cleaning performance (LR) of the vacuum cleaner (2) from an initial value (WA) for a predefinable period of time (T) if the dirt value (WS) or the reduction value (WR) exceeds a dirt limit value (GS). Vacuum cleaner (2) according to one of the preceding claims, characterized in that - the vacuum cleaner (2) contains a cleaning roller (20), - the floor sensor (28) is configured to determine the degree of hardness (GH) based on a current operating value of the cleaning roller (20). Vacuum cleaner (2) according to one of the preceding claims, characterized in that the control module (32) is switchable at least between automatic mode (MA) and a real mode (MR) as mode (M) and is configured in real mode (MR) to output the dirt value (WS) instead of the reduction value (WR) on the display module (30) even for the hardness level (GH) above the soft floor limit value (GW). Vacuum cleaner (2) according to one of the preceding claims, characterized in that the display module (30) contains a cleanliness indicator (34) which indicates the falling below a predefinable cleanliness value (WE) by the dirt value (WS) or reduction value (WR). vacuum cleaner (2) according to one of the preceding claims, characterized in that the display module (30) contains an information display (36) which displays context information (IK) to the currently selected mode (M). Method for operating the vacuum cleaner (2) according to one of the preceding claims, wherein: - the dirt sensor (26) determines the dirt value (WS), - the floor sensor (28) determines the hardness level (GH), - the control module (32) in automatic mode (MA), - for a hardness level (GH) below the soft floor limit value (GW): - outputs the dirt value (WS) on the display module (30), - and otherwise, - in addition to the dirt value (WS), determines the reduction value (WR) and outputs it on the display module (30).

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