High-responsiveness level sensor for hygiene consumable

Abstract

A sensor arrangement for detecting a filling state of a reservoir of a hygiene consumable comprising: a set of sensors arranged along a depletion direction of the reservoir, each sensor being configured to detect presence of hygiene consumable in its respective proximity, and a processing section being coupled to said set of sensors for obtaining a presence detection from individual sensors of said set of sensors, wherein the sensor arrangement is configured to provide a varying acquisition density, and wherein the acquisition density increases in said depletion direction.

Description

[0001] HIGH-RESPONSIVENESS LEVEL SENSOR FOR HYGIENE CONSUMABLE

[0002] Technical field

[0003] The present invention relates to detecting a filling level of a reservoir of a hygiene consumable, such as soap, disinfectant, tissue, towel, and the like. In particular, the present invention relates to responsiveness in a level sensor for a hygiene consumable in a piece of hygiene equipment such as a dispenser of that consumable.

[0004] Background

[0005] The benefits of proper hygiene, in particular in the form of hand hygiene, are widely acknowledged. It is commonplace that public or commercial facilities such as washrooms in public buildings, offices, restaurants, airports, hospitals, shopping malls and so on are normally provided with dispensers for various hygiene consumables, for example paper towels, liquid soap, disinfectant, tissues, toilet paper, or sanitary napkins.

[0006] Such consumables are normally stored in dispensers, which may be fixedly located at suitable positions in the washroom or other locations. A dispenser can for example be in the form of a holder for paper towels or tissues, a holder for toilet paper, a holder for diapers, or a container for liquid soap, disinfectant or other consumable. Further, also used items, such as towels or tissues, may still be considered as a hygiene consumable and respective equipment for receiving such used consumables may be waste bins or other receptacles for receiving and containing such used consumables .

[0007] In the above context it is oftentimes desirable to know about the filling level of a piece of hygiene equipment such as a dispenser or waste bin. Usually, knowledge on the filling state is desired in order to initiate and plan the refilling of dispensers, emptying bins or other receptacles, or other service activities. For this purpose, it is already known to provide said hygiene equipment with level sensors that are configured to measure and report a filling state of the respective consumable. Such sensors are usually provided with a sensor arrangement that can detect a measured figure that relates to the filling state (such as a distance, weight, presence, and the like) , and some kind of logging and / or reporting function that provides the relevant information to an applicable service entity. For example, the sensors report respective filling states to a service center from which refills or replacements can be initiated .

[0008] However, such sensors are oftentimes battery powered or employ energy harvesting techniques (such as solar cells) and thus the available power may be limited. At the same time, however, the sensors should provide a reliable measurement output for allowing a high-quality management of the hygiene equipment. In addition to this, there are applications in which the demand for hygiene consumable varies substantially during time in the sense that there are times during which demand remains relatively low and the reservoirs of the hygiene equipment depletes relatively slow, and, that there are times during which demand for hygiene consumable surges and reservoirs may deplete relatively fast.

[0009] Such demand behavior may occur in larger installations, such as stations, airports, cultural or sport venues and the like. For example, hygiene equipment installed in a sports stadium may be used relatively little if there is no match or other event. However, demand for hygiene equipment surges during a match and the reservoir of the hygiene equipment may deplete quickly. For obtaining a satisfactory quality of service (QoS) one may want to be able to react quickly in such situations by initiating or facilitating refills promptly.

[0010] There is therefore a need for an improved sensor arrangement for detecting a filling state of a hygiene consumable that can be employed in hygiene equipment that provides high responsiveness at still low power consumption. In other words, there is a need for sensor arrangements that can quickly react to surges in demand whilst making efficient use of the respectively available power resources .

[0011] Summary

[0012] The mentioned problems are solved by the subject-matter of the independent claims. Further preferred embodiments are defined in the dependent claims.

[0013] According to an aspect of the present invention, there is provided a sensor arrangement for detecting a filling state of a reservoir of a hygiene consumable comprising a set of sensors arranged along a depletion direction of the reservoir, each sensor being configured to detect presence of hygiene consumable in its respective proximity, and a processing section being coupled to said set of sensors for obtaining a presence detection from individual sensors of said set of sensors, wherein the sensor arrangement is configured to provide a varying acquisition density, and wherein the acquisition density increases in said depletion direction.

[0014] According to an aspect of the present invention, there is provided a piece of hygiene equipment for dispensing and / or receiving a hygiene consumable, comprising a sensor arrangement according to one of the disclosed embodiments.

[0015] According to a method aspect of the present invention, there is provided a method of operating a piece of hygiene equipment, such as a dispenser for a hygiene consumable, or a sensor arrangement according to one of the disclosed embodiments for detecting a filling state of a reservoir of a hygiene consumable. Speci fically, there i s provided a method of operating a sensor arrangement for detecting a f il ling state of a reservoir of a hygiene consumable compris ing, the sensor arrangement compri sing a set of sensors arranged along a depletion direction of the reservoir , each sensor being conf igured to detect presence of hygiene consumable in its respective proximity, the method compris ing a step of providing a varying acqui sition density, and wherein the acqui sition density increases in said depletion direction .

[0016] Brief Description of the Drawings

[0017] Embodiments of the present invention , which are presented for better understanding the inventive concepts and which are not to be seen as l imiting the invention, wil l now be described with reference to the Figures in which :

[0018] Figures 1A and IB show general device embodiments of the present invention for a sensor arrangement detecting a fi ll ing state of a reservoir of a hygiene consumable ;

[0019] Figures 2A and 2B show general operation aspects of sensor arrangements detecting a f il ling state of a reservoir of a hygiene consumable according to embodiments of the present invention ;

[0020] Figures 3A to 3F show dif ferent types of hygiene equipment in which a f il ling state of a reservoir of a hygiene consumable is detected according to embodiments of the present invention ;

[0021] Figures 4A and 4B show general measuring concepts involved in detecting a fi ll ing state of a reservoir of a hygiene consumable according to embodiments of the present invention; and

[0022] Figure 5 shows a flow chart of a general method embodiment of the present invention.

[0023] Detailed description

[0024] Figures 1A and IB show general device embodiments of the present invention for a sensor arrangement detecting a filling state of a reservoir of a hygiene consumable. While Figure 1A shows a modular example of such a sensor arrangement, Figure IB focusses on the functional elements at a more general level. The reference numerals are however used for the same elements in both depictions. According to embodiments of the present invention, there is provided a sensor arrangement 10 for detecting a filling state of a reservoir of a hygiene consumable. The sensor arrangement 10 comprises a set of sensors 110 arranged along a depletion direction D of the reservoir that is subject to filling state monitoring. Generally, the mentioned reservoir may form part of a piece of hygiene equipment and holds a supply of the hygiene consumable (e.g. paper towels, soap, etc.) . During use the supply diminishes and the reservoir correspondingly depletes. This is assumed to happen along a specific direction which is indicated with the so-called depletion direction. For example, a stack of paper towels is depleted whilst one end of the stack moves along that depletion direction.

[0025] An individual sensor 110-i of the set of sensors is configured to detect presence of hygiene consumable in its respective proximity. In this way, a filling state can be derived from information that indicates what sensor (s) of the set of sensors "see" consumable (i.e. detect presence) and what sensor (s) of the set of sensors do not "see" consumable (i.e. do not detect presence or detect absence) . For this purpose, the set of sensors are arranged along the depletion direction. Further details on measuring presence of consumable are provided elsewhere in the present disclosure and specifically also in conjunction with Figures 4A & 4B.

[0026] The sensor arrangement 10 further comprises a processing section 120 that is coupled to said set 110 of sensors for obtaining a presence detection from individual sensors thereof. The sensor arrangement 10 may further comprise a memory 130 storing data related to the measurement and reporting process, including program data for instructing the processing section 120 to perform one or more of the actions and functionalities as described elsewhere in the present disclosure. The sensor arrangement 10 may further comprise a communication section 140 for accessing remotely stored data or information and / or forward any report on any measured or determined figure to a network 160, such as the "Cloud" or the Internet. The sensor arrangement 10 may further comprise a battery or other power supply 150 in the form of any one of a battery cell, a rechargeable battery, a super-capacitor, an energy harvesting device, a solar or light cell, a e / m-wave receiver, and the like. The sensor arrangement 10 can further comprise a housing 100, wherein an elongate housing bar 101 may accommodates the set of sensors 110.

[0027] Generally, the processing section may provide processing resources for implementing some or all functionalities locally, i.e. at the site of the sensor arrangement, or also at least in part remotely in the sense that the processing for implementing any functionality is provided by a remote data centre. In such a later case, there may be involved data communication between the site of the sensor arrangement and a network, for example via the already mentioned communication section 140. As the sensors are, however, bound to the location of the consumable, the processing section may at least provide the driving and the reading out of the sensors, such as voltage and / or current supply, analogue-to-digital conversion, and / or receiving digital data from sensors over a local protocol (e.g. I2C, SPI, IWire, and the like) . According to the embodiments of the present invention, the sensor arrangement 10 is configured to provide a varying acquisition density, and wherein the acquisition density increases in said depletion direction D. Generally, a varying acquisition density includes changing the acquisition of measurement results from the set of sensors 110 from at least a first scheme of a relatively coarse measurement resolution to at least a second scheme of a relatively fine measurement resolution. The resolution can be in terms of time (s) , period (s) , precision, position, resolution, and fidelity of measurement. For example, obtaining a measurement result from a sensor more often and / or obtaining a measurement result from more proximate sensors provide a higher acquisition density as compared to, respectively, a measurement that takes place less often and that comes from sensors that are located less closely to each other.

[0028] Figure 2A shows a device and respective operation aspects of sensor arrangements detecting a filling state of a reservoir of a hygiene consumable according to embodiments of the present invention. As shown, a sensor arrangement 10 is employed in a piece of hygiene equipment, here, as an example, shown in the form of dispenser 1. The exemplary dispenser 1 provides a reservoir 200 for a supply 20 of hygiene consumable in the form of paper towels 2 that a user can draw from the dispenser 1 from a bottom side 19. Other examples for relevant pieces of hygiene equipment are shown and described in conjunction with Figures 3A through 3F. In the shown form, the supply 20 will move downwards as users take paper towels 2 and the reservoir 200 will accordingly deplete along the depletion direction D. The generally applicable elements of the sensor arrangement 10 have been described in conjunction with Figures 1A & IB.

[0029] According to this embodiment, the varying acquisition density is provided by means of said processing section 120 being configured to vary an acquisition interval for obtaining a presence detection from individual sensors. Specifically, one or more sensors of the set 110 of sensors are addressed to acquire a detection result. In the shown example, reading the sensors 110- 1 and 110-2 would yield no presence of hygiene consumable as the supply 20 moved already downwards along the depletion direction. More details for the detection as such are provided in conjunction with Figures 4A & 4B. The sensors 110-1, 110-2, and the remaining sensors of the set 110 of sensors may be provided along the depletion direction D with a substantially equal distance to each other. As the supply 20 depletes, more and more sensors 110-i would provide a detection result of no hygiene consumable in its respective proximity. From the position of one or more sensors that yield presence / no presence or a fraction of the number of sensors that yield presence against a number of sensors that do not yield presence a filling state can be conceived and calculated. For example, in the shown example, four sensors would yield no presence which roughly corresponds to a filling state of less than 50%.

[0030] Generally, the operation scheme may consider obtaining information on the filling state of the reservoir by addressing at least one of the set of sensors and by obtaining a presence detection from the addressed sensor. Further, the processing section may follow a specific sequence of addressing individual sensors in order to further reduce power consumption. For example, the processing section may be configured to obtain start information indicating an individual sensor to be used as a start sensor; address the sensor indicated by the start information and obtain a first presence detection result from the addressed sensor; if the first presence detection result indicates no presence of hygiene consumable, address a subsequent sensor arranged downstream relative to the previously addressed sensor and in the depletion direction, and obtain a subsequent presence detection result from the addressed sensor; if the subsequent presence detection result indicates presence of hygiene consumable, store information indicating the addressed subsequent sensor as the start information.

[0031] In this embodiment, the processing section 120 is configured to vary an acquisition interval for obtaining a presence detection from individual sensors, in the sense that a time interval between two consecutive measurement cycles is changed. For example, the processing section 120 may be configured to acquire a presence detection from relevant sensors periodically with a first tie period. If this time period is decreased, the sensor arrangement will acquire and obtain presence detection more often, and, in this way, in a more precise manner as the measurement provides a higher time resolution. This is shown in time sequence likewise shown in Figure 2A as measurement points Ml, M2, and M3, with a respective time interval Ti between respective measurements. The processing section 120 can be generally configured to vary the time length T of the acquisition interval for varying the acquisition density.

[0032] In an embodiment, the processing section 120 may be configured to obtain information on a filling state F of the reservoir 200, determine whether the filling state F has decreased and, if so, decrease the acquisition interval T. For example, the filling state Fi of the reservoir may be well above 50% for some time including the measurement points Ml to M3. The piece of hygiene equipment may then be subject to increased usage, i.e. in the form of a surge in the demand for the hygiene consumable supplied by the dispenser 1. As the supply depletes, the filling state F will increase. For example, the processing section 120 may be configured to determine whether the filling state F has decreased by determining that it has fallen below a pre-determined threshold at x%. In this case, the processing section 120 may be configured to decrease the acquisition interval T to Tf.

[0033] It is noted that also one or more additional, intermediate acquisition interval (s) may apply that lie between Ti and Tf in terms of time duration. In this way, a gradual variation of the acquisition density may be obtained. Further, the acquisition density may also be decreased after it has increased in the depletion direction. For example, it may be determined that the reservoir is empty and that this has been already reported, so that it may not be necessary to maintain a high level of responsiveness. Therefore, the embodiments may provide for decreasing the acquisition density again, once a certain depletion level has been reached, e.g. by increasing again an acquisition interval to some default value that may at least allow for reliably and sufficiently promptly determine that a refill has taken place.

[0034] As a consequence, the sensor arrangement has increased the acquisition density as the reservoir runs low. In this way, an increased responsiveness is obtained as the sensor arrangement can detect and report the filling state more promptly and, accordingly, a refill or any other service action can be initiated without delay. At the same time, though, the sensor arrangement is considerate of power consumption, as the interval may be longer, resulting in less acquisition cycles and lower power consumption, in times when the supply is still sufficiently full and / or demand is sufficiently low.

[0035] In a further embodiment, the processing section 120 may be configured to use an acquisition interval of more than 30 minutes, preferably more than 10 minutes, if the information on the filling state indicates a filling state of more than 50% of the reservoir, and to use an acquisition interval of less than 10 minutes if the information on the filling state indicates a filling state of less than 50% of the reservoir. In the shown example, Ti would be accordingly set to, for example, 30 or 10 minutes which would result in 48 readings per day. This may be sufficient whenever the supply is high or demand is low. Naturally, this may also apply to situations in which demand is high but also the supply is high enough so that no refill becomes necessary soon. Further, also a situation of low supply may be tolerable when supply is low.

[0036] However, the acquisition interval may be decreased to 1 minute, so as to be able to react more promptly once demand has picked up and / or supply runs low. In this way, there is provided an advantageous solution also for larger scape applications, such as airports or stadiums, so that the sensor arrangement consumes little power when the place is less busy (e.g. at nights or when there is no match) , whilst "switching" to a higher responsiveness when supply has depleted as use picks up after, for example, a plane has landed and passengers disembark or visitors use restrooms during a half-time break. In any way, the provided embodiments may allow prompt reaction in situations of high demand as refills or other service routines can be initiated quickly .

[0037] Figure 2B shows a device and respective operation aspects of sensor arrangements detecting a filling state of a reservoir of a hygiene consumable according to embodiments of the present invention. Specifically, this may be an example for the general case that the varying acquisition density is provided by means of an at least in part varying distance between two neighbouring sensors. As shown as an example of that, a sensor arrangement 10 comprises a set of sensors 110-1, 110-2, ..., 110-6, 110-7. In this embodiment, the sensors 110-i are again arranged along a depletion direction D including a depletion range starting at some full level F and ending at some empty level E. However, the sensors 110-i are arranged at a smaller distance dE to each other toward the end E of the depletion direction D as compared to the distance dF to each other toward the start F of the depletion direction D. Generally, it can be assumed that reservoir depletes in the depletion direction D from a beginning F of the depletion direction to an end E of the depletion direction.

[0038] Further, at least one distance dE between two neighbouring sensors 110-6, 110-7 may be relatively small toward the end E of the depletion direction D as compared to at least one distance dF between two neighbouring sensors 110-1, 110-2, being relatively large toward the beginning F of the depletion direction D. In this way, measurements are finer or have a higher resolution as the reservoir depletes. In this way, a relatively coarse measurement (and mapping between sensor and filling state) can be accepted when a need for refill is less likely as the reservoir is still relatively full, whilst the precision is increased once a need for a refill becomes more likely. More specifically, in such embodiments, the relatively small distance between two neighbouring sensors may correspond to less than 20%, preferably less that 10% of a filling capacity of the reservoir and the relatively large distance between two neighbouring sensors may correspond to more than 20%, preferably more than 10% of the filling capacity. In general, however, the distance between sensors may vary also for other sections in the depletion direction, e.g. other than the sections towards a beginning and / or an end of the depletion direction.

[0039] Figures 3A to 3F show different types of hygiene equipment in which a filling state of a reservoir of a hygiene consumable is detected according to embodiments of the present invention. Figure 3A shows a schematic view of a dispenser 1-1 that is arranged to dispense a hygiene consumable in a liquid form. For example, this may be a soap dispenser or a dispenser for a disinfectant such as alcohol or alcogel. Predominantly for such a dispenser type the depletion direction D will be from the top to the bottom as the supply of the consumable will accumulate toward the bottom. The measured figure may be in relation to a top surface of the supply and a maximum height of the reservoir. A sensor arrangement 10 as described in the respective embodiments of the present disclosure may be arranged as shown.

[0040] Figure 3B shows a schematic view of a dispenser 1-2 that is arranged to dispense a hygiene consumable such as a tissue or paper towel 2. The dispenser 1-2 has a reservoir 200 with a given supply 20 of hygiene consumable, in the present exemplary case a stack of paper towels 2. A user can take one towel from an opening on a bottom side 19 of the dispenser 1-2, which will make the reservoir 200 gradually deplete in the depletion region D as the supply 20 diminishes. A sensor arrangement 10 as described in the respective embodiments of the present disclosure may be arranged as shown.

[0041] Figure 3C shows a schematic view of a similar dispenser 1-3 that is arranged to dispense a hygiene consumable such as a tissue or paper towel. The shown dispenser may be in principle similar as that shown in conjunction with Figure 3B except for that the depletion direction D may be from the bottom to the top. Namely, there exist tissue dispenser that push a supply upwards so that a user can pull out one or more towels / tissues from the top. Mechanical spring action may be involved to push up the tissue supply as consumables are dispensed. This configuration may provide the opportunity for measuring a distance between a sensor position and the position of a well-defined element such as the support that pushes the consumable supply upwards. In this way, the sensor (e.g. TOF or light ref lection / absorption) may be more independent from the consumable as such as measurement do not depend on optical or other physical properties of the consumable. A sensor arrangement 10 as described in the respective embodiments of the present disclosure may be arranged as shown.

[0042] Figure 3D shows a schematic view of a dispenser 1-4 that is arranged to dispense a hygiene consumable such as a tissue or paper towel 2' . In this case, the consumable is an endless towel supply 2’ which may have perforations in between individual towels to be dispensed. Namely, a user can pull on the supply from the bottom side 19 of dispenser 1-4 in which the supply is led upwards and then again over one or more rolls 18 again downwards (see partial cut outs of the dispenser front and the supply moving downwards) . The dispenser 1-4 has again a reservoir 200 with a given supply 20' of hygiene consumable, in the present exemplary case an endless concatenation of paper towels 2' . Taking one towel from an opening on that bottom side 19 of the dispenser 1-4 will make the reservoir 200 gradually deplete in the depletion region D as the supply 20' diminishes. It is noted that in this regard the behaviour is similar to the dispenser 1- 2 described in conjunction with Figure 3B, although the consumable will first move upwards and then downwards. Specifically, a sensor arrangement 10 as described in the respective embodiments of the present disclosure may be arranged in dispenser 1-4 and would operate just as in the case of dispenser 1-2. For this, it may be provided that the paper 2' moves upwards and downwards relatively close to the front and rear dispenser housing wall, whereas the sensor 10 is arranged substantially there in between.

[0043] Figure 3E shows a schematic view of a dispenser 1-5 that is arranged to dispense a hygiene consumable in the form of a roll, such as toilet paper. In such types, a diameter of the roll can act as an end or limit of the supply, whereas the position of the sensor may be again a fixed point for any distance measurements. It is noted that this concept may apply to both types of roll dispensers, namely rolls that supply from the outside (depletion direction D, distance to be considered between outer roll diameter and sensor position) as well as rolls that supply from the inside (depletion direction D' , distance to be considered between inner roll diameter and sensor position) . A sensor arrangement 10 as described in the respective embodiments of the present disclosure may be arranged as shown.

[0044] Figure 3F shows a schematic view of a piece of hygiene equipment in the form of a waste bin 1-6 that is arranged to receive a used hygiene consumable in the form of towels, tissues, and the like. In such types, the reservoir is for used consumables and the filling state will increase over time rather than decrease as is the case for the earlier discussed types of hygiene equipment. A full reservoir is then an indication for the need of emptying the bin or replacing a full bin liner with a new one. However, the general concepts of the present invention naturally apply accordingly. Especially, also any considerations relating to a filling state and a depletion direction, in that the reservoir is seen as free capacity to receive further used consumables. Thus, during use of a piece of hygiene equipment of that type the reservoir will also deplete along a depletion direction, as, for example, the reservoir for holding additional material will deplete upwards, and as shown with the depletion direction D in Figure 3F, while the bin is in use. A sensor arrangement 10 as described in the respective embodiments of the present disclosure may be arranged as shown.

[0045] Figures 4A and 4B show general measuring concepts involved in detecting a filling state of a reservoir of a hygiene consumable according to embodiments of the present invention. In Figure 4A there is shown a sensor arrangement 11 with a so-called time of flight, TOF, sensor 111 which is arranged to measure a figure that indicates a distance d between a sensor location L and a limit of hygiene consumable in the reservoir, in the shown case an upper end of a supply 20 at S. In principle, the distance d can lie substantially in the depletion direction D. In such embodiments, the acquisition density can be varied by means of changing an acquisition interval / frequency at which the TOF sensor is driven and read out. Further, the acquisition density can be varied by operating such a sensor in different modes that include one mode in which the sensor provides a relatively high precision, fidelity or resolution, and another mode in which the sensor provides a relatively low precision, fidelity or resolution. Further, in the latter mode the sensor may consume less power as compared to a higher precision mode.

[0046] In a TOF arrangement, the time of flight will relate to the time the probe signals travels from the sensor to the consumable and back therefrom which would at some point in time require considerations that the measured time indicates a distance which is longer than and roughly twice as much as the distance d of interest. The TOF sensor 111 may comprise any one of an ultrasonic sensor, a radar sensor, a light sensor, a laser sensor, and a focussed light source. For example, a suitable TOF sensor may be sensor "VL53L1X" manufactured by ST Microelectronics. Such sensors may provide accurate ranging up to 4 m and a ranging frequency up to 50 Hz. Housed in a compact package, such sensors may integrate a so-called, single photon avalanche diode, SPAD, receiving array, a 940 nm invisible Classi laser emitter, physical infrared filters, and optics to achieve the desired performance in various ambient lighting conditions. Such sensors may allow for absolute distance measurement relatively independent from the target color and reflectance.

[0047] In Figure 4B there is shown a sensor arrangement 12 with wherein the sensor 12 comprises a set of sensors 121-1, 121-2,..., 121-n, which may be arranged along the depletion direction D of the reservoir 200. In such a configuration, each sensor 121-i is configured to detect presence of hygiene consumable in its respective proximity. This may be implemented by means of capacitive or light sensors that produce a distinguishable output in relation to whether or not there is supply of consumable next to it (i.e. in the respective vicinity) . Generally, the sensor can be any one of light barrier sensor, a reflection sensor, a proximity sensor, and a capacitive sensor. For example, a light signal may be reflected (at least in part) by the consumable while it may be absorbed A by a reservoir wall when there is no consumable. Likewise, a light signal may be reflected R by a reservoir wall when there is no consumable but absorbed by the consumable.

[0048] In such embodiments, the acquisition density can be varied by means of changing an acquisition interval / frequency at which the relevant sensors 122-i are driven and read out. Further, the acquisition density can be varied by means of a varying distance between two adjacent relevant sensors 122-1 which has been described also in conjunction with Figure 2B. Yet further, the acquisition density can be varied by operating such a sensor in different modes that include one mode in which the sensor provides a relatively high precision, fidelity or resolution, and another mode in which the sensor provides a relatively low precision, fidelity or resolution. For example, the output power of a probe signal (light, ultrasound, voltage, etc.) may be varied which may yield less fiddle measurement results at potentially lower power consumption as compared to higher precision measurement results at a potentially higher power consumption .

[0049] Figure 5 shows a flow chart of a general method embodiment of the present invention. The method embodiments are for operating a sensor arrangement for detecting a filling state of a reservoir of a hygiene consumable as that has been described elsewhere in the present disclosure. The sensor arrangement comprises a set of sensors arranged along a depletion direction of the reservoir, wherein each sensor is configured to detect presence of hygiene consumable in its respective proximity. The sensor arrangement further comprises a processing section that is coupled to the set of sensors. In a step S100, the processing section may employ at least one of said set of sensors for obtaining a presence detection. Generally, the sensor arrangement provides in a step S200 a varying acquisition density which increases in the depletion direction. It should be noted that the method of operation comprises varying (S200) the acquisition density at least once between two consecutive presence detections (S200) . For example, the varying in step S100 may comprise any one of varying an acquisition interval and addressing different sensors that have a varying or di fferent di stance toward a neighbouring sensor .

[0050] According to a further embodiment there i s provided a sensor arrangement for detecting a f il ling state of a reservoir of a hygiene consumable compri sing a set of sensors arranged along a depletion direction of the reservoir , each sensor being configured to detect presence of hygiene consumable in its respective proximity, and a process ing section being coupled to said set of sensors for obtaining a presence detection from individual sensors of said set of sensors , wherein at least one distance between two neighbouring sensors i s relatively small toward an end of the depletion direction as compared to at leas t one distance between two neighbouring sensors being relatively large toward the beginning of the depletion direction .

[0051] Alternatively or in addition to the above , there may be provided a sensor arrangement for detecting a fi ll ing state of a reservoir of a hygiene consumable compris ing a set of sensors arranged along a depletion direction of the reservoir, each sensor being configured to detect presence of hygiene consumable in its respective proximity, and a process ing section being coupled to said set of sensors for obtaining a presence detection from individual sensors of said set of sensors , wherein the process ing section i s conf igured to vary an acqui sition interval for obtaining a presence detection from individual sensors , obtain information on a f il ling state of the reservoir, determine whether the fi ll ing state has decreased and, i f so , decrease the acqui sition interval .

[0052] Although detailed embodiments have been described, these only serve to provide a better understanding of the invention def ined by the independent claims and are not to be seen as l imiting .

Claims

Claims :

1. A sensor arrangement for detecting a filling state of a reservoir of a hygiene consumable comprising: a set of sensors arranged along a depletion direction of the reservoir, each sensor being configured to detect presence of hygiene consumable in its respective proximity, and a processing section being coupled to said set of sensors for obtaining a presence detection from individual sensors of said set of sensors, wherein the sensor arrangement is configured to provide a varying acquisition density, and wherein the acquisition density increases in said depletion direction.

2. The sensor arrangement according to claim 1, wherein the varying acquisition density is provided by means of an at least in part varying distance between two neighbouring sensors .

3. The sensor arrangement according to claim 1 or 2, wherein the reservoir depletes in the depletion direction from a beginning of the depletion direction to an end of the depletion direction.

4. The sensor arrangement according to claim 2 and 3, wherein at least one distance between two neighbouring sensors is relatively small toward the end of the depletion direction as compared to at least one distance between two neighbouring sensors being relatively large toward the beginning of the depletion direction.

5. The sensor arrangement according to claim 4, wherein the relatively small distance between two neighbouring sensors corresponds to less than 20% of a filling capacity of the reservoir and the relatively large distance between two neighbouring sensors corresponds to more than 20% of the filling capacity.

6. The sensor arrangement according to any one of claims 1 to5, wherein the varying acquisition density is provided by means of said processing section being configured to vary an acquisition interval for obtaining a presence detection from individual sensors.

7. The sensor arrangement according to claim 6, wherein the processing section is configured to obtain information on a filling state of the reservoir, determine whether the filling state has decreased and, if so, decrease the acquisition interval.

8. The sensor arrangement according to claim 7, wherein the processing section is configured to use an acquisition interval of more than 10 minutes if the information on the filling state indicates a filling state of more than 50% of the reservoir, and to use an acquisition interval of less than 10 minutes if the information on the filling state indicates a filling state of less than 50% of the reservoir.

9. The sensor arrangement according to any one of claims 1 to 8, wherein the processing section is configured to obtain information on the filling state of the reservoir by addressing at least one of the set of sensors and by obtaining a presence detection from the addressed sensor.

10. The sensor arrangement according to claim 9, wherein the processing section is configured to obtain start information indicating an individual sensor to be used as a start sensor; address the sensor indicated by the start information and obtain a first presence detection result from the addressed sensor; if the first presence detection result indicates no presence of hygiene consumable, address a subsequent sensor arranged downstream relative to the previously addressed sensor and in the depletion direction, and obtain a subsequent presence detection result from the addressed sensor; if the subsequent presence detection result indicates presence of hygiene consumable, storeinformation indicating the addres sed subsequent sensor as the start information .11 . The sensor arrangement according to any one of claims 1 to10 , further compri sing a housing, wherein an elongate housing bar accommodates the set of sensors .12 . The sensor arrangement according to any one of claims 1 to11 , wherein the sensor is any one of light barrier sensor, a reflection sensor, a proximity sensor, and a capacitive sensor .13 . A sensor arrangement for detecting a f i ll ing state of a reservoir of a hygiene consumable compris ing : a set of sensors arranged along a depletion direction of the reservoir, each sensor being configured to detect presence of hygiene consumable in its respective proximity, and a process ing section being coupled to said set of sensors for obtaining a presence detection from individual sensors of said set of sensors , wherein at least one distance between two neighbouring sensors i s relatively small toward an end of the depletion direction as compared to at least one distance between two neighbouring sensors being relatively large toward the beginning of the depletion direction .14 . A sensor arrangement for detecting a f i ll ing state of a reservoir of a hygiene consumable compris ing : a set of sensors arranged along a depletion direction of the reservoir, each sensor being configured to detect presence of hygiene consumable in its respective proximity, and a process ing section being coupled to said set of sensors for obtaining a presence detection from individual sensors of said set of sensors ,wherein the processing section is configured to vary an acquisition interval for obtaining a presence detection from individual sensors, obtain information on a filling state of the reservoir, determine whether the filling state has decreased and, if so, decrease the acquisition interval.

15. A piece of hygiene equipment, preferably a dispenser for a hygiene consumable, comprising a sensor arrangement according to any one of claims 1 to 14.

16. A method of operating a sensor arrangement for detecting a filling state of a reservoir of a hygiene consumable comprising, the sensor arrangement comprising a set of sensors arranged along a depletion direction of the reservoir, each sensor being configured to detect presence of hygiene consumable in its respective proximity, the method comprising a step of providing a varying acquisition density, and wherein the acquisition density increases in said depletion direction.

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