Level sensor and dispenser

Abstract

A solution for detecting level of a consumable tissue product (201, 301) in a tissue dispenser (103, 106) located in a washroom. This is provided in a number of aspects such as a tissue dispenser, a method, system, and a sensor unit utilizing two sensor elements (420, 430), each arranged to measure light reflected from a reflection field located on the tissue product, reflected directly from the tissue product, or measure the absence of the tissue product. Data from the sensor elements are wirelessly transmitted to a server (901) for further handling, such as for instance notification to a janitor in charge of service of the washroom.

Claims

1. A tissue dispensing system, comprising: a tissue holder arranged to receive a tissue product to be dispensed from the tissue holder, the tissue holder comprising at least one sensor collection unit arranged on the tissue holder, the at least one sensor collection unit comprising: at least one sensor collection processing unit, at least one communication interface, at least two sensor elements, each of the two sensor elements comprising a light source and a light detector and the two sensor elements being separated a distance from each other in at least one direction relative to the tissue product, each of the at least two sensor elements is arranged to transmit light from the light source towards the tissue product and detect reflected light in the light detector, and wherein the at least one sensor collection processing unit is configured such that sensing intervals at which the at least the two sensor elements transmit light is adjustable, and wherein an interval at which the at least one communication interface communicates results of the at least two sensor elements is adjustable; a data collection unit comprising at least one data collection processing unit and a communication unit configured to receive difference signals from the at least one sensor collection unit; and a third processing unit configured to receive and analyze data from the communication unit and determine a level of the tissue product in the tissue holder; and wherein the data collection unit is arranged to receive difference signals from the at least one sensor collection unit, and to communicate information to the third processing unit for analysis and level determination.

2. The tissue dispenser according to claim 1, wherein the difference signal is determined based on two separated reflection fields on the tissue product.

3. The tissue dispenser according to claim 1, wherein the light detector comprises a photo detector or a light emitting diode operating in reverse mode.

4. The tissue dispenser according to claim 1, wherein the light detector is arranged to provide a signal relative to a reflectivity level of an area of the tissue product.

5. The tissue dispenser according to claim 1, further comprising a tissue refill provided with a reflectivity level of an area of the tissue product so as to provide a reflection reference.

6. The tissue dispenser according to claim 5, wherein the reflection reference provides information about at least one of a level on the tissue refill, a type of tissue product, and a quality of tissue product.

7. The tissue dispenser according to claim 5, wherein the tissue refill comprises at least one reflection field.

8. The tissue dispenser according to claim 5, wherein the processing unit is arranged to determine if the tissue refill changed for another position.

9. The tissue dispenser according to claim 1, wherein each sensor element is arranged to detect at least one of a reflective field and absence of a reflective field.

10. The tissue dispenser according to claim 1, wherein the at least two sensor elements provide information about at least 3 different qualities of tissue product.

11. The tissue dispenser according to claim 1, wherein the difference signal is communicated to the central server via a data collection unit via a short range wireless communication technology.

12. The tissue according to claim 1, wherein the sensor collection unit is arranged to detect the level of the tissue product by sensing at least one of a reflectivity level of an area of the tissue product, at least one reflection field, and absence of the tissue product.

13. The tissue dispensing system according to claim 1, further comprising: at least one server which includes the third processing unit.

14. The system according to claim 13, wherein the system is arranged to detect the washroom tissue product of at least 3 different qualities.

15. The system according to claim 13, wherein the system is arranged to detect the level of washroom tissue product by sensing at least one of a reflectivity level of an area of a tissue refill, at least one reflection field, and absence of the tissue product.

16. A tissue refill product for the tissue dispenser according to claim 1, the tissue refill product arranged with at least one reflective field located on at least one side of the tissue refill product.

17. The tissue refill product according to claim 16, wherein the at least one reflective field comprises information about identity of the tissue refill product.

18. The tissue refill product according to claim 17, wherein the identity of the tissue refill product is based on at least one of reflectivity of the reflective field and location of a plurality of reflective fields.

19. The tissue dispenser according to claim 1, wherein a first one of the at least two sensor elements senses a first extent of the issue product, and a second one of the at least two sensor elements senses a second extent of the tissue product.

20. The tissue dispenser according to claim 1, wherein the data collection processing unit is arranged to obtain signals from the reflected light from each of the sensor elements, and at least one of the obtained signals is communicated to the central sever when one of the at least two sensor elements senses an extent of the tissue product and a second one of the at least two sensor elements does not sense the level of tissue product.

21. A tissue dispenser, comprising: a tissue holder arranged to receive a tissue product to be dispensed from the tissue dispenser; at least one sensor collection unit arranged on the tissue holder, the one sensor collection unit comprising at least one sensor collection processing unit, at least one communication interface, and at least two sensor elements, each of the two sensor elements comprising a light source and a light detector and the two sensor elements being separated a distance from each other in at least one direction relative to the tissue product, each of the at least two sensor elements is arranged to transmit light from the light source towards the tissue product and detect reflected light in the light detector, and wherein the at least one sensor collection processing unit is configured such that sensing intervals at which the at least the two sensor elements transmit light is adjustable, and wherein an interval at which the at least one communication interface communicates results of the at least two sensor elements is adjustable; and wherein the sensor collection processing unit is arranged to determine a difference signal the reflected light from each of the sensor elements in relation to each other such that the level of tissue product in the tissue holder can be determined, and to communicate the difference signal to a central server for subsequent analysis using the communication interface; wherein the level of tissue product is determined in at least three different levels comprising information relative to need of refill of tissue product: refill not needed, refill soon to needed, and refill is needed.

22. A method of detecting a level of a tissue product in a dispenser, the dispenser comprising at least one sensor collection unit positioned in the dispenser, the at least one sensor collection unit including first and second optical sensor elements separated from each other in at least one direction relative the tissue product, the method comprising: obtaining a first sensor signal from the first optical sensor element arranged to detect reflected light; obtaining a second sensor signal from the second optical sensor element arranged to detect reflected light; using a data collection unit with a communication unit to receive data from the at least one sensor collection unit; and receiving data from the data collection unit and determining a level of the tissue product in the tissue holder; wherein each of the sensor elements of the at least one sensor collection unit is arranged to transmit light from the light source towards the tissue product and detect reflected light in the light detector, wherein the at least one sensor collection processing unit is configured such that sensing intervals at which the first and second optical sensor elements transmit light are adjustable, and wherein an interval at which the at least one communication interface communicates results of the at least two sensor elements is adjustable, and wherein the data collection unit is arranged to determine a difference between signals from the sensor elements in the one sensor collection unit.

23. The method according to claim 22, further comprising communicating the difference to a central server using a communication interface.

24. The method according to claim 22, wherein the tissue product comprises at least one reflection field.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic block diagram of a local system according to an embodiment of the present invention;

(2) FIGS. 2A and B are a schematic illustration in two different angles of a dispenser according to an embodiment of the present invention;

(3) FIGS. 3A and B are a schematic illustration in two different angles of another dispenser according to an embodiment of the present invention;

(4) FIGS. 4A and B is a schematic block diagram of a sensor collection unit according to two embodiments of the present invention;

(5) FIG. 4C is a schematic block diagram of a data collection unit according to an embodiment of the present invention;

(6) FIG. 5 is a schematic illustration of a general method according to an embodiment of the present invention;

(7) FIG. 6 is a schematic illustration of a refill configuration according to an embodiment according to an embodiment of the present invention;

(8) FIG. 7 is a schematic illustration of a refill configuration according to another embodiment according to an embodiment of the present invention;

(9) FIG. 8A to E is a schematic illustration of an operation of the solution according to an embodiment of the present invention;

(10) FIG. 9A, C, D is a schematic illustration of an operation of the solution according to an embodiment of the present invention, and

(11) FIG. 10 is a schematic illustration of a system according to an embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(12) In FIG. 1, reference number 100 generally indicates a washroom comprising a number of toilet stalls 101 with toilet seats 102 and toilet tissue dispensers 103. Furthermore, a cleaning area is provided with a number of sinks 104 and equipped with soap dispensers 105 and towel tissue dispensers 106. The washroom may also be provided with a data collection unit (DCU) 107. Each dispenser may be arranged with a detection device, for instance a sensor collection unit (SCU), for determining a level of each dispensing product and a communication interface for communicating the level to the DCU or to a central server (not shown) for further handling.

(13) The tissue dispensers may be one of two different types: dispensers providing a web of sheet material from a continuous roll of absorbent material and may be periodically perforated for separation or cut by the dispenser or dispensers providing pre cut tissue sheets stacked in a pile. For instance the former type is often used in toilet tissue dispensers and the latter in towel tissue dispensers providing paper for wiping hands after washing.

(14) In FIG. 2 a dispenser 210 providing a sheet material stacked in a pile 201 inside a tissue dispenser holder 200 is illustrated together with a sensor collection unit 203 (SCU). In FIG. 2 a dispensing sheet 202 is shown. The SCU is arranged to detect the level of the sheet material and may also be arranged to detect the type of material, e.g. the quality of the material.

(15) In FIG. 3 a dispenser 310 providing a web of continuous material in a roll 301 in a tissue dispenser holder 300 is shown. Also in this embodiment a sensor collection unit 303 (SCU) is provided for determining the level of the material and optionally the type/quality of the material. The roll may be arranged with a channel for accommodating a rotation axis 304 for loading in the dispenser or the roll may be attached to the dispenser in any other suitable way allowing for rotation of the roll as the material is dispensed.

(16) An exemplary sensor collection unit (SCU) 400 is shown in FIG. 4A, comprising at least one processing unit 401 (CPU), at least one storage unit 402 (STOR), such as a memory unit, at least one communication unit 403 (COM), and at least one sensor element 420 and 430.

(17) Each sensor element may comprise a light transmitter 404 and 406, e.g. a LED, laser, or lamp, and a light detector, e.g. a LED or a photo detector 405 and 407. Each sensor elements may alternatively comprise both a light transmitter and a light detector in the same sensor unit, e.g. using a LED; this may be seen in FIG. 4B with sensor units 421 and 431 each comprising a combined light transmitter and light detector; i.e. the same unit operates both as light transmitter and light detector for instance in a switching manner or incorporated into the same component. The two sensor elements 420 and 430 are separated a distance from each other preferably in a direction relative the general movement of the tissue when dispensed; however, as will be shown later this is not always the case.

(18) The light transmitter 404, 406 transmits light on to the tissue product, the light is reflected or is dissipated if no tissue product is available; thereafter the reflected light is detected by the detector 405, 407 or the LED detects the absence of tissue product. The LED detector may be a normal LED, e.g. similar to the LED transmitter, operating in “reverse” mode, i.e. when light is directed on to the LED a small current will be produced and this may be detected using appropriate amplification and filtering electronics. The light transmitted from the transmitter may be of any suitable wavelength including, but not limited to, visible, ultraviolet, or infrared wavelengths. It should be noted that the light transmitter and light detector may be separate components or they may be mounted in the same casing and provided as a single component.

(19) The components of the SCU are mounted on a circuit board and appropriately mounted in a casing with light transmitter/detector openings. The SCU may further comprise a power supply, e.g. a battery, light transmitter/detector electronics, e.g. amplification circuitry, drive circuitry, filter circuitry, power supply control circuitry, and circuitry connecting the different functional elements together. The processing unit may comprise any suitable type of unit executing instructions sets of software or hardware program; the processing unit may for instance be a central processing unit (CPU), a microprocessor, a micro controller, a field programmable gate array (FPGA), or an application specific integrated circuit (ASIC). The memory unit may be arranged to hold instructions sets for operating the SCU, calibration data and other similar data, and measurement data from the at least one sensor. The processing device is also arranged to communicate with at least one external device, such as for instance a data collection unit (DCU). The memory unit may comprise at least one of a volatile and/or non-volatile memory type memory, for instance at least one of a read only memory, random access memory (RAM), electrical erasable programmable memory (EEPROM), flash memory, hard disk, and so on. The communication unit may be arrange to use any suitable short range communication method, for instance using publicly available unlicensed ISM band (industrial, scientific and medical), e.g. Bluetooth, Wireless local area network (WLAN) according to any suitable standard such as 802.11 standard series, or proprietary communication protocols. It should be appreciated that also long range communication protocols may be used, for instance GSM, GPRS, EDGE, UMTS, LTE, WCDMA, CDMA2000, and so on. It should be noted that ISM bands may operate at several different approximate center frequencies such as 6.78 MHz, 13.56 MHz, 27.12 MHz, 40.68 MHz, 433.92 MHz, 916 MHz, 2.45 GHz, 5.8 GHz, 24.125 GHz, 61.25 GHz, 122.5 GHz, and 245 GHz. For instance, a short range device (SRD) uses advantageously a low power radio communication solution operating at any suitable unlicensed wireless communication radio. The frequency interval for the sensing or the radio communication may be changed according to different demands, for instance depending on type of dispenser or battery consumption demands. The sensing intervals as well as the radio communication intervals might e.g. be in intervals of 1 per second, 1 per 10 seconds, 1 per minute, 1 per 5 minutes, every 480 seconds, 1 per 10 minutes, 1 per hour, 1 per day or any suitable time interval there between or longer or shorter

(20) The data collection unit (DCU) 415 comprises, as seen in FIG. 4C, at least one processing unit 410, at least one memory unit 411, at least one SCU communication unit 412, and at least one long range communication unit 413. The processing unit is arranged to execute instruction sets for operating the DCU as to collect data from the SCU(s) and relay these data to a central server as will be discussed in more detail with reference to FIG. 9. The DCU receives data from the SCU(s) using the DCU communication unit operating with the same communication protocol as the communication interface at the SCU(s). Communication may also be received directly by a central server from the SCU; in this case each SCU or a sub set of SCU's has long range communication interfaces and may transmit data directly to the server. In case of a sub set of SCU comprises long range communication interfaces, these SCU's also may comprise a short range communication interface in order to communicate with SCU's only comprising short range communication interfaces. This may be seen as an ad-hoc network solution where the SCU's together form a network with each other and some SCU's may relay data to the server or directly to a device operated by the janitor or similar person in charge of maintaining the washroom. It should be appreciated that the SCU communication unit may operate with several different radio protocols, for instance by having a plurality of radio communication units and/or using a software-defined radio unit. This enables the deployment of SCU(s) at different occasions and upgrading of SCU(s) when new technology becomes available or if an SCU is broken and need to be replaced. The processing unit of the DCU relays the data via the long range communication interface and via a communication network to the server. The long range communication unit may operate with any suitable type of communication mode/protocol, e.g. GSM, GPRS, EDGE, UMTS, HSDPA, LTE, WCDMA, CDMA2000, and so on as understood by the skilled person and the communication network may be an infrastructure network for the above mentioned communication protocols and/or a packet based communication network such as the Internet or an intranet.

(21) It should be noted that even though an embodiment of the present invention has been exemplified with wireless communication between the SCU and DCU and the DCU and the server, alternatively wired connection may be utilized at either connection, e.g. using Ethernet standard. Furthermore, non radio based wireless communication protocols may be used between the SCU and DCU, e.g. infrared communication technology. Furthermore, alternatively, the SCU may communicate directly with the server or with equipment operated by the janitor using a long range wireless communication mode.

(22) The level detector advantageously comprises two separate elements each with a transmitter and detector as discussed earlier. The two elements are separated a distance from each other relative the dispensed product in order to get readings on different parts of the dispensed product. This two elements feature may be useful for increasing the readability of the level detector. The tissue material may be arranged with a reflective field on a side of the refill, which reflective field may be used for reflecting the light from the transmitter and optionally providing a reference of known reflectivity. This reflective field may for instance be applied on only part of the tissue product side as will be discussed later below. However, it should be noted that the two separate elements may be arranged so as to detect different types of reflectivity of the tissue refill, for instance such as one sensor unit detects light reflected from a portion of the refill with a reflective field and the other sensor unit detects light reflected from a portion of the refill without a reflective field—thus signals from the two sensor units will be different and a difference signal may be provided increasing the signal to noise ratio and thus the readability of the level. By varying the reflectivity level of an area of the tissue product or the reflective field it is possible to provide identification of different types of material or different qualities of material. The sensor elements are arranged to detect different contrast values since the transmission light output may be calibrated and may therefore be considered known. Using fields with different reflectivity contrast, e.g. with different colors or grey scales, fields with density gradients, or different intensities, e.g. different intensities of colors, it is possible to provide information about the level, quality, type, and/or brand of the product—the solution may determine a measure of reflectivity level. The reflective field may be made of different dyes of different color, different intensities, a fluorescent material, a phosphorescent material, or different textures creating differences in reflectivity as compared to surrounding areas of the product. The fields may be printed or mechanically provided on the product. The reflectivity level of an area of the tissue may also refer to reflective properties of the tissue paper as well as a reflection field provided on the tissue paper. The reflectivity level of an area of the tissue provides a reflection reference which could provide info about the type of tissue product, quality of tissue product, etc. The reflection reference can also give information about the location on the tissue refill and can refer to the reflective properties of the tissue paper or reflective fields. It should thus be noted that the use of reflective fields is not necessary, but that reflection of the light may be provided directly on the material of the product; however, at the expense of possibly making it more difficult to detect the quality or type of the material. If the quality is to be determined without reflective fields, the sensor unit needs to determine the reflectivity level with higher accuracy and determine the quality from this measurement. The sensor elements are arranged to detect any area capable of reflecting light and/or the absence of tissue product. Use of UV transmitters/detectors may for instance be used to discriminate between virgin or recycled paper since they comprise different levels of whiteners that behave differently in UV light.

(23) The placement of the sensor elements in the dispenser may be varied depending on the type of dispenser, dispenser height, and/or tissue product. For instance the sensor elements may be provided on a rail and may be repositioned and fastened on the rail if so needed.

(24) As for large dispensers, they can be refilled as soon as there is space enough in the dispenser; a problem in such a situation may be that consumption might not be correctly monitored with only one SCU/detection device since it is placed somewhere close to a dispensing outlet, such that the last refill is detected by the SCU unit. In such cases more detection units, i.e. SCU(s) may be required in order to get a relevant level indication.

(25) The sensor elements may comprise different types of light detectors, e.g. LEDs operating in different wavelength areas. One detector may operate in the UV area and the other in the visible or infrared area. Furthermore, the detectors may be of different quality providing different signals depending on the reflectivity level or reflective fields. The use of different types of detectors and/or transmitters may also be used for providing detection of quality of tissue product. The signal strength from the detector will vary depending on light provided and quality of tissue product, for instance reflective properties of recycled tissue paper will depend on recycled content and thus vary from different production batches whereas reflective properties in the visible regime will depend on paper brightness. This may be seen in table 1 below indicting reflectivity for different types of paper and detectors:

(26) TABLE-US-00001 TABLE 1 Recycled Hybrid Virgin UV detector (recycled High Medium Low content) LED detector (paper Low Medium High brightness)

(27) With the term recycled in table 1 is meant a paper comprising a high content of recycled paper, with the term virgin with a low content of recycled paper, and the term hybrid paper comprising both recycled and virgin paper.

(28) The same differences may also be found when using different types of coloring of the transmitter and depending on type of light detector each color will give different responses in the light detector. Table 2 indicates differences in detector response as a function of color:

(29) TABLE-US-00002 TABLE 2 Blue Yellow-Green Red Detector range 450-500 nm High Medium Low Detector range 640-700 nm Low Medium High

(30) The detector range number indicates a wavelength range where the detector is optimized and is given in nanometers.

(31) One may also combine different types of transmitters and detectors, for instance using a UV LED transmitter together with a RED LED 640 operating in reverse mode may give a good possibility to separate different qualities of paper. Recycled paper may give a low signal in the detector with ordinary LED sensors due to low brightness, whereas the UV sensor would yield a high signal due to high content of fluorescent material in the paper. In virgin qualities the opposite is true, where a LED 640 sensor will yield high signal strength due to the better reflection of the bright paper—the UV sensor yields low signal levels due to the low content of fluorescent material in the virgin paper. Combining the different types of transmitters and detectors may provide suitable separation of different qualities. It should be noted that the two sensor elements may also comprise different combinations.

(32) FIG. 5 illustrates a method according to an embodiment of the present invention that utilizes a difference signal measurement solution. Periodically, the SCU reads data from each sensor element. The SCU takes a reading from a first sensor element and thereafter takes a reading from a second sensor element, step 501 and 502 respectively. The sensor data is analyzed 503 for determining a difference signal. From the difference signal the current level may be determined 504 of the dispenser refill. Depending on the current level different action may be taken and handled. It should be noted that the analysis and level determination may be executed in the SCU, the DCU, the server, or in a combination of these, e.g. analysis of data in SCU or DCU and level determination in server. It should be noted that the level may be determined with high resolution, such as a percentage of the full refill, or within pre defined levels, e.g. no refill needed, refill needed shortly, refill needed immediately, or changed to another position, such as e.g. a stub roll position, or similarly broadly defined levels. Furthermore, the solution may be arranged to determine consumption of consumable rather than a certain level, e.g. determining when a stack of tissue product refill has been depleted and thus at least one stack of tissue product may be inserted into the dispenser.

(33) FIG. 6 illustrates some examples of reflective fields on a tissue stack. FIG. 6A shows an example with a single reflective field 604 on the stack 601. SCU 400 has two sensor elements 420 and 430 reading data from the stack and depending on the level of the stack different signals will be obtained; this will be discussed in more detail further below.

(34) FIG. 6B shows an example where the reflective field on the stack 602 is divided into several separate fields 605 and 606. Depending on how the reflective fields are located in respect to the sensor elements 420, 430 different signals will be obtained that can increase information about level and/or type of material in stack.

(35) FIG. 6C shows still another example where the reflective fields on the stack is further divided which provides the possibility to increase the number of types/qualities of products that may be identifiable by the system. In FIG. 6C four different reflective fields 607-610 have been illustrated, but it should be appreciated that the invention is not limited to these alternatives.

(36) In applications with a continuous roll of web material another variation of reflective field may be used as can be seen in FIG. 7. The roll 700 may have an optional channel 702 through the roll for easy loading in a dispenser and has a reflective field 703 on a flat side 701 of the roll. The SCU 400 with its sensors detects the level of the product using the reflective fields as discussed earlier for instance in relation to FIG. 6; also in this application a plurality of fields of reflection may be used.

(37) FIG. 8 illustrates an example of how a reading of a reflectivity level of an area of the tissue may be changed during dispensing of the product. Further, FIG. 9 illustrates a variant of the solution as shown in FIG. 8, wherein reflective fields are not used but only the reflectivity of the tissue product 601 itself is used, i.e. a reflectivity level of an area of the tissue product provide information about the level. During the first step A both sensor elements 420 and 430 of the SCU 400 detect the presence of tissue product 601, i.e. there is no indication that the level of the tissue product is too low. In the next step C, one sensor element 420 detects the presence of tissue product whereas the other sensor element 430 does not detect the presence of tissue product, i.e. the tissue product is starting to get too low and a replacement is needed within a short time. Finally, in step D none of the sensor elements detect any tissue product, i.e. a signal may be triggered that the tissue product is very low or has been depleted and refill is needed immediately. In FIG. 8 a stack of tissue is shown, but it should be appreciated that the same process may be applicable to a continuous web of tissue in a roll. In the first stage (A) the stack is full and each of the sensor elements 420 and 430 of the SCU 400 detect a reflective field. As the stack height decreases due to the dispensing of the product the tissue refill and the reflectivity level of an area of the tissue, and in FIG. 8 the reflection field moves further down as seen from the perspective of the sensor elements and in stage B the reflective field is now in a position where the lowest element 420 detects a reflective field but not the highest sensor element 430—this may provide some information about the current level of the stack. In a further step C the lowest sensor element does not detect a reflective field as in FIG. 8 but still detects the stack whereas the highest sensor element 430 does not detect either the reflection field or the stack—this may trigger a first reaction, for instance triggering the SCU to send a first signal to the DCU or server informing that the stack is getting lower and that refill may be needed some time soon; for instance notification to the janitor to include this dispenser in the coming service round. The server may transmit information to a device operated by the janitor, e.g. in a simple form as a text message to a mobile phone or smart phone; however, it should be noted that special software to be executed in the device of the janitor may be developed for more complex handling of refill and service interval operations; for instance graphical display of each washroom and which dispensers that needs to be refilled and so on. In step D the stack is so low that none of the sensor elements 420 or 430 detects a reflection field or the stack and this may trigger a second reaction, for instance sending a second signal to the DCU informing that the stack is of immediate risk of depletion and that refill of the dispenser should be done. It should be noted that also the second stage B may trigger a reaction for informing about the current level situation. In some dispenser solution several piles of tissue may be stacked on top of each other, which, relating to FIG. 8, may be understood from step E where a second stack 801 with its reflection field 804 is stacked on top of the old stack 601; in this example the lowest sensor element will detect a stack but no reflection field and the highest sensor element will detect a reflection field—which may be interpreted by the SCU, DCU or server as there being another stack on top of the other and there is thus no immediate need for refill.

(38) The analysis of the current product level, and/or possibly also product qualities, may be executed in the SCU, DCU, or the server. For instance, since the SCU advantageously is battery operated, the analysis is executed in the DCU or server in order to preserve power consumption and prolong the life time before battery replacement is needed. The frequency of detection that the SCU performs may also be adjusted depending on application and desired power consumption when the SCU is battery operated.

(39) The data is transmitted to a server 1001 as illustrated in FIG. 10 showing a system according to an embodiment of the present invention. The system comprises at least one SCU 400, at least one optional DCU 107, and the server 1001. Each SCU transmits wirelessly a signal indicating the current level in a respective dispenser to a DCU 107 or directly to the server 1001 as discussed earlier. A plurality of DCUs may be attached to the system and each DCU is in turn arranged to transmit received signals, either in received form or in analyzed form depending on configuration of the system, upstream to a server using a communication network 1010; advantageously the DCU communicates wirelessly with the communication network which in turn relays the communication data to the server. The server 1001 may be arranged to execute a number of different operations depending on configuration of the system, such as analysis of SCU or DCU signals for determining current level in each dispenser, identify product quality, identify each SCU and corresponding dispenser together with geographical location, keeping track of an inventory, generating reports, transmitting a signal, e.g. a text message, to a user equipment 1002 issued to the janitor for indicating refill of dispenser at a location, and even order products from a distributor 1003 if products availability is getting low at the inventory. The janitor receiving the signal may act upon this and depending on the need for refill, he/she can make a note to refill during next service round or to immediately react and urgently refill the dispenser at the location. The user equipment 1002 may be any suitable device able to communicate with the server directly or indirectly, such as a mobile phone, personal digital assistant (PDA), smart phone, pager, tablet computer, laptop, computer in janitor office area, and so on.

(40) The server may serve several locations of a customer and even several different customers. Customers may be for instance a cleaning company handling in turn one or several clients, office locations which handle their own cleaning or maintenance of washrooms, or organization such as schools, retirement homes, hospitals, and similar organizations providing locations with public or semi public washrooms.

(41) The network 1010 may be any suitable network that may transmit data from the DCU to the server, including but not limited to 4G, 3G, GSM, GPRS, UMTS, LTE, IP based network, Ethernet, the Internet, or similar packet data enabled network solutions directly or in a combination of some of these solutions.

(42) The operation of a central server and real time tracking of use of tissue products open up new revenue streams by providing new business cases, such as keeping track of statistics of use for tissue suppliers enabling more efficient manufacturing and distribution, decreasing service intervals of washrooms, more optimal scheduling of service personnel at different locations, decreasing stocks of tissue products, and so on.

(43) It should be noted that the word “comprising” does not exclude the presence of other elements or steps than those listed and the words “a” or “an” preceding an element do not exclude the presence of a plurality of such elements. It should further be noted that any reference signs do not limit the scope of the claims, that the invention may be at least in part implemented by means of both hardware and software, and that several “means” or “units” may be represented by the same item of hardware.

(44) The above mentioned and described embodiments are only given as examples and should not be limiting to the present invention. Other solutions, uses, objectives, and functions within the scope of the invention as exemplified in the below described embodiments should be apparent for the person skilled in the art.

ABBREVIATIONS

(45) GSM Global System for Mobile Communications

(46) GPRS General Packet Radio Services

(47) EDGE Enhanced Data Rates for GSM Evolution

(48) UMTS Universal Mobile Telecommunications System

(49) LTE Long Term Evolution

(50) WCDMA Wideband Code Division Multiple Access

(51) CDMA2000 Code Division Multiple Access 2000

(52) HSDPA High Speed Downlink Packet Access

(53) SCU Sensor Collection Unit

(54) DCU Data Collection Unit

(55) IP Internet Protocol