WO2020082189A1

WO2020082189A1 - Method of measuring the uv-radiation in sunlight and device for performing the method

Info

Publication number: WO2020082189A1
Application number: PCT/CH2018/000043
Authority: WO
Inventors: Samuel WELTEN
Original assignee: Ink-U-Beta Ag
Priority date: 2018-10-23
Filing date: 2018-10-23
Publication date: 2020-04-30
Also published as: WO2020083819A3; WO2020083819A2

Abstract

The invention concerns a method of measuring the UV-radiation in sunlight by means of a measuring device (2) using one or several photovoltaic cells (8, 8a, 8b) as sensor for determining the UV-radiation, wherein at least a part of said photovoltaic cells (8, 8a, 8b) which are used as sensor furthermore are used as a generator for generating electrical power for said measuring device (2). By doing so, sensing of the UV-radiation and generating electrical power for the Operation of the device (2) can be accomplished with the same surface area, and thus very small UV measuring devices (2) with a high degree of autonomy become possible.

Description

Method of measuring the UV-radiation in sunlight and device for performing the method

TECHNICAL FIELD

The invention concerns a method of measuring the UV-radiation in sunlight by means of a measuring device using one or several photovoltaic cells as sensor for determining the UV-radiation, a measuring device for use in said method and an arrangement comprising said measuring device according to the preambles of the independent claims.

BACKGROUND ART

Sunlight is essential for the life on earth. It is for example needed for plant growth and for vitamin D production in humans.

However, due to the UV-radiation which is part of the sunlight, overexposure to sunlight for humans also has several detrimental effects, like e.g. sunburn, rapid skin ageing or even skin cancer. Every year millions of humans come down with skin cancer, mainly due to the UV-radiation in the sunlight.

A basic problem is that humans do not have direct senses for UV-radiation, which is not visible for them, and thus often cannot judge their exposure to UV- radiation and the effects and risks encountered therewith.

In order to facilitate a meaningful exposure to sunlight, mobile UV measuring devices have been developed and are commercially available by means of which the actual intensity of UV-radiation and often also the accumulated amount of UV-radiation over a certain exposure time can be determined. Especially for persons with skin cancer such devices are of great help in order to reduce exposure to UV-radiation and therewith increase their prospects, of recovery.

For evaluating the total exposure to UV-radiation of a person as precise as possible, the person has to carry the UV measuring device all day long, and at a place of the body where it is always exposed to any light the person is exposed to. This calls for devices which are as inconspicuous and small as possible and do not require any maintenance . The target in today's developments is to provide UV measuring devices with a size and with an autonomy that enables them to become part of the clothing of a person, e.g. in the form of a button or sticker, so that they are not recognized as devices anymore by the user and by other persons.

To be as autonomous as possible, some of the available mobile UV measuring devices are equipped with photovoltaic cells, .which charge an energy storage

(capacitor or accumulator) from which the device obtains the energy for its operation.

For measuring the UV-radiation in the sunlight, different concepts are known in the art.

Some of the known UV measuring devices use special UV-sensors on the basis of aluminium gallium nitride, gallium nitride or silicium carbide, which however are quite expensive compared to sensors for measuring radiation in the visible range of sunlight. In order to save costs, in most applications sensors having a very small sensing surface are employed, resulting in a weak signal that needs to be amplified quite extensively in order to be convertable into a digital signal and thus a low signal-to-noise-ratio results which in turn does not allow for a precise measurement .

Other known mobile UV measuring devices use sensors which are sensitive to visible radiation in com- bination with special optical filters for measuring the UV-radiation in the sunlight. US 5, 382, 986 A for example discloses sunglasses with an integrated UV measuring device using two identical photodiodes the sensitive areas of which are covered by different optical band-pass filters, one that transmits only UV-A radiation and one the transmits both, UV-A and UV-B radiation.

From US 7,271,393 B2, an UV measuring device is known which for measuring the UV-radiation in the sunlight uses two identical visible light sensors, one of which is covered by a filter that changes its transmis- sibility for visible radiation as a function of the UV- radiation it is exposed to.

US 5,151,600 A discloses a noseshade for monitoring the exposure to UV-radiation. Here, for measuring of the UV-radiation two photovoltaic cells are employed which are covered by different optical band-pass filters, transmitting the UV-A and UV-B radiation, respectively.

All the afore mentioned known concepts suffer from the disadvantage that in case the UV-measuring device shall be autonomously powered by sunlight, beside the surface area needed for sensing the UV-radiation additional equally exposed surface areas on the device are needed for generating electrical power. This, however, quite considerably limits the potential for further miniaturization of such devices in order to allow them to become part of the clothing o.f a person, e.g. in the form of a button or sticker.

DISCLOSURE OF THE INVENTION

Hence, it is a general object of the invention to provide technical solutions which do not have the before described disadvantages of the prior art or at least partially avoid them.

This object is achieved by the subjects of the independent claims . Accordingly, a first aspect of the invention concerns a method of measuring the quantity of UV-radia- tion in sunlight. For performing the method, a measuring device using one or several photovoltaic cells as sensor for determining the UV-radiation is employed and accor- ding to the invention, at least a part of said photovoltaic cells which are used as sensor are furthermore used as generator for generating electrical power for said measuring device. By doing so, sensing of the UV-radiation and generating electrical power for the operation of the device can be accomplished with the same surface areas, and thus very small UV measuring devices with a high degree of autonomy become possible.

By advantage, all electrical power used for the operation of the measuring device is generated by said one or several photovoltaic cells which are used as sensor and as generator. By doing so, the light exposed surface area of the measuring device employed in the method can be reduced to the minimum surface area required for generating the electrical power for its opera- tion.

In a preferred embodiment of the method, the measuring device furthermore is used for transmitting data representing the UV-radiation to a receiving unit, by means of which the quantity of UV-radiation, e.g. the actual intensity of UV-radiation and/or the accumulated amount of UV-radiation over a certain exposure time, can be made recognizable or is made recognizable. Transmission of said data representing the UV-radiation preferably takes place in wireless manner, e.g. by Bluetooth.

By doing so, the measuring devices can be fully autonomous and can be placed anywhere within the reach of reception of the receiving unit.

Preferably, the data representing the UV- radiation are transmitted to the receiving unit in fixed intervals or in variable intervals, that are depending on the available solar energy. When doing so it is furthermore preferred that the data representing the UV-radiation which are transmitted to a receiving unit are in each case determined directly before they are transmitted to the receiving unit.

The before mentioned features make a continuous monitoring of the UV-radiation possible even at very low lighting levels.

The receiving unit preferably is a mobile phone, in particular a smart phone with an App adapted to make recognizable the quantity of UV-radiation. This has the advantage that information about the quantity of UV- radiation can be made recognizable in a convenient and discrete manner .

The electrical power generated by at least some of said one or several photovoltaic cells which are used as sensor and as generator when in use as generator preferably is stored in an energy storage, like e.g. one or several accumulators or capacitors. Capacitors provide the advantage that they are robust and can also be used in applications where they have to withstand temperatures near to 100^eC, e.g. in sports clothes which are washed at high temperatures .

In a preferred embodiment of the method, at least a part of the photovoltaic cells which are used as sensor and as generator are temporarily used as sensor and temporarily used as generator, preferably alternately, e.g. in fixed intervals or in intervals resulting from the operating conditions of the device, like e.g. the charging conditions of the measuring device.

For example, in case the electrical power generated by at least some of said one or several photovoltaic cells which are used as sensor and as generator is stored in an energy storage, it is preferred that when the energy storage during charging reaches a certain charging level (e.g. 95%· capacity) , the use of said one or several photovoltaic cells as generator is stopped and these photovoltaic cells then are temporarily used as sensor for determining the UV-radiation.

In that case it is furthermore preferred that, while said one or several photovoltaic cells are in use as sensor for determining the uv-radiation, the mea- suring device consumes electrical energy from the energy storage, thereby lowering its charging level.

Preferably, after the determination of the UV-radiation and/or after the charging level of the energy storage has dropped to a certain threshold value (e.g, 50% capacity) , said one or several photovoltaic cells again are used as generator for charging the energy storage.

By doing so, the measuring intervals are triggered by the operating conditions of the device .

If any time said one or several photovoltaic cells have been used as sensor for determining the UV- radiation data representing the determined UV-radiation are transmitted to the receiving unit, which is preferred, the device does not need its own data memory and can be very simple, small and robust .

In another preferred embodiment of the method, at least a part of said one or several photovoltaic cells which are used as sensor and as generator are simultaneously used as sensor and as generator.

In this case it is preferred that the measuring device employed in performing the method has an energy storage for the electrical power it needs for its operation and that for charging the energy storage, exclusively photovoltaic cells are used the power production rate of which mainly depends on the amount of UV- radiation they are exposed to. By means of these photovoltaic cells, the energy storage is charged starting from a defined lower charging level (e.g. 10 % capacity until it reaches a defined upper charging level (e.g. 98 % charging level) . The time needed for charging the energy storage from the defined lower charging level to the defined upper charging level is determined and from the determined charging time, the quantity of UV-radia^¬ tion is evaluated.

This method is very simple and reliable, and it requires only one single photovoltaic cell.

By advantage, each time the energy storage reaches the defined upper charging level, it is set back to the defined lower charging level and the energy storage again is charged by the photovoltaic cells until it reaches the defined upper charging level . Thus, any time the defined upper charging level is reached, a new determination of the charging time with a subsequent evaluation of the quantity of UV-radiation is started.

In a first variant of this embodiment of the method, each time the energy storage reaches the defined upper charging level, a signal is send to a receiving unit, which, based on the time intervals between the signals, evaluates the quantity of UV-radiation . This method is extremely simple and can be performed with simple and robust measuring devices .

In a second variant of this embodiment of the method, each time when the energy storage reaches the defined upper charging level , the quantity of UV-radiation is evaluated by the measuring unit and preferably data representing the evaluated quantity of UV-radiation are transmitted to a receiving unit, in particular each time the quantity of UV-radiation is evaluated or in predetermined intervals. This method requires more advanced measuring devices than the before mentioned one.

In the method according to the invention it is preferred to determine the actual intensity of UV- radiation and/or the accumulated amount of UV-radiation over a certain exposure time.

In a further preferred embodiment of the method, the one or several photovoltaic cells which are used as sensor and as generator are solar cells which are sensitive for both, UV-radiation and visible light. Such solar cells are commercially available in diverse embodiments and at competitive prices.

In a first preferred variant of this embodiment, the solar cells used are of identical type and part of them by means of an optical filter are made less sen- sitive or non-sensitive to UV-radiation. In doing so, by comparing the power yields of the solar cells with optical filters and without optical filters, the energy portion contributed by UV-radiation can be identified and used for evaluation the amount of UV-radiation.

In a second preferred variant of this embodiment, one or several optical filters are used to change the sensitivity characteristics of one or several of these solar cells, and in particular, wherein one, in particular exactly one such solar cell is used which has been made non-sensitive for visible light by a filter. From the power yields of this or these solar cells, which originate from the UV-radiation in the sunlight, the amount of UV-radiation can be evaluated.

In another preferred embodiment .of the method, the one or several photovoltaic cells which are used as sensor and as generator are photovoltaic cells which are mainly sensitive for UV-radiation. Preferably, exactly one such photovoltaic cell is used. From the power yields of these solar cells, which originate from the UV-radiation in the sunlight, the amount of UV-radiation can be evaluated.

For details of different methods of evaluating the amount of UV-radiation in sunlight by means of sensors and/or photovoltaic cells, and in particular by means of sensors and/or photovoltaic cells which by means of optical filters have been made sensitive to different spectrums of radiation, it is .referred to the prior art identified in the introductory part of the description.

A second aspect of the invention concerns a measuring device for use in the method according to the first aspect of the invention. The device comprises one or several photovoltaic cells and a measuring unit capable of using said photovoltaic cells as sensor for determining UV-radia- tion. The measuring device is designed in such a manner that the photovoltaic cells which are used as sensor for determining the ^" CJV—radiation can also be used as generator for generating electrical power for said device. By the invention it becomes possible to provide very small measuring devices, since sensing of the UV-radiation and generating electrical power for the operation of the device can be accomplished with the same surface area.

By advantage, the measuring device is designed in such a manner that all the electrical power used by it is exclusively generated by the one or several photovoltaic .cells which are used as sensor and as generator, i.e. there is nd additional power source required and there are also no photovoltaic cells at the measuring device which serve exclusively for power production. Thus, the light exposed surface area of the measuring device in this embodiment can be reduced to the minimum surface area required for generating the electrical power for its operation, so that extremely small measuring devices become possible.

In a preferred embodiment, the measuring device is designed in such a manner that by means of it, data representing the UV-radiation can be transmitted to a receiving unit, by means of which the quantity of UV- radiation, e.g. the actual intensity of UV-radiation and/or the course and the accumulated amount of UV-radiation over a certain exposure time, can be made recogniz- able or is made recognizable. Transmission of said data representing the UV-radiation preferably can take place in wireless manner, e.g. by Bluetooth. By this, the measuring devices cart be fully autonomous and can be placed anywhere within the reach of reception of the receiving unit. Preferably, the measuring device is designed in such a manner that the data representing the UV-radia- tion is transmitted to the receiving unit in fixed intervals or in variable intervals, that are depending on the available solar energy.

When doing so it is furthermore preferred that the measuring device is designed in such a manner that the data representing the UV-radiation which is transmitted to a receiving unit is in each case determined directly before it is transmitted to the receiving unit.

The measuring device preferably comprises an energy storage, e.g. one or several accumulators or capacitors, in which the electrical power generated by at least some of said one or several photovoltaic cells which are used as sensor and as generator when in use as generator can be stored. Capacitors provide the advantage that they are robust and can also be used in applications where they have to withstand temperatures in the region of 100°C.

In a preferred embodiment, the measuring device is designed in such a manner that at least a part of the photovoltaic cells which are used as sensor and as generator are temporarily used as sensor and temporarily used as generator, preferably alternately, e.g. in fixed intervals or in intervals resulting from the operating conditions of the device.

For example, in case the device comprises an energy storage in which the electrical power generated by at least some of said one or several photovoltaic cells which are used as sensor and as generator is stored, it is preferred that, the device is designed in such a manner that, when the energy storage during charging reaches a certain upper charging level (e.g. 95% capacity), the use of said one or several photovoltaic cells as generator is stopped and these photovoltaic cells then are temporarily used as sensor for determining the UV-radiation.

In that case it is furthermore preferred that the measuring device is designed in such a way that, while said one or several photovoltaic cells are in use as sensor for determining the UV-radiation, the measuring device consumes electrical energy from the energy storage, thereby lowering its charging level .

Preferably, the measuring device is further- more designed such that after the determination of the

UV-radiation and/or after the charging level of the energy storage has dropped to a certain threshold value (e.g. 50% capacity) , said one or several photovoltaic cells again are used as generator for charging the energy stor- age. Thus, the measuring intervals are triggered by the operating conditions of the device, namely by the time it takes to charge the energy storage starting from the threshold value until it reaches the upper charging level, which time depends on the amount of electrical ener- gy produced by the photovoltaic cells.

By advantage, the measuring device furthermore is designed in such a manner that, any time said one or several photovoltaic cells have been used as sensor for determining the UV-radiation, data representing the determined UV-xadiation are transmitted to the receiving unit. By this, the advantage is arrive at that the device does not need its own data memory and can be very simple, small and robust.

In another preferred embodiment, the measuring device is designed in such a manner that at least a part of said one or several photovoltaic cells which are used as sensor and as generator can simultaneously be used as sensor and as generator.

In this case it is preferred that the measuring device has an energy storage for the electrical power it needs for operation and is designed such that for charging this energy storage, exclusively photovoltaic cells are used the power production rate of which mainly depends on the amount of UV-radiation they are exposed to, that by means of these photovoltaic cells, the energy storage is charged starting from a defined lower charging level (fe.g. 10 % capacity) until it reaches a defined upper charging level (e.g. 98 % charging level) and that the time needed for charging the energy storage from the defined lower charging level to the defined upper charging level can be determined, by the device itself or by evaluation of signals emitted or transmitted by the device. Such measuring devices can be designed very simple and can be realized with only one single photovoltaic cell.

By advantage, the measuring device is designed in such a manner that each time the energy storage reaches the defined upper charging level, it is set back to the defined lower charging level and the energy storage again is charged by the photovoltaic cells until it reaches the defined upper charging level. Thus, any time the defined upper charging level is reached, a new determination of the charging time with a subsequent evaluation of the quantity of UV-radiation is started.

In a first variant of this embodiment, the device is designed such that each time the energy storage reaches the defined upper charging level, a signal is send to a receiving unit, which, based on the time intervals between the signals, Can evaluate the quantity of UV-radiation. Such measuring devices can be designed quite simple and robust.

In a second variant of this embodiment of the measuring device, the device is designed in such a manner that each time when the energy storage reaches the defined upper charging level, the quantity of UV-radiation is evaluated by the measuring unit.

In this variant, the measuring device preferably is furthermore designed in such a manner that data representing the evaluated quantity of UV-radiation are transmitted to a receiving unit, in particular each time the quantity of UV-radiation is evaluated or in predetermined intervals. Such devices are more sophisticated than the first variant and can provide more functionality than the aforementioned.

Preferably, the measuring device according to the invention is designed in such a manner that in the intended operation it can be used for determining actual UV-radiation values and/or accumulated UV-radiation values over a certain span of time.

In a further preferred embodiment of the measuring device, the one or several photovoltaic cells which are used as sensor and as generator are solar cells which are sensitive for both, UV-radiation and visible light. Such solar cells are commercially available in diverse embodiments and at competitive prices.

In a first preferred variant of this embodiment of the measuring device, the solar cells are of identical type, and part of them by means of an optical filter are made less sensitive or non-sensitive to UV-radiation. With these solar cells, by comparing the power yields of the cells with optical filters and without optical filters, the energy portion contributed by UV-radiation can be identified and can be used for evaluation of the amount of UV-radiation,

In a second preferred variant of this embodiment of the measuring device, it comprises one or several optical filters by which the sensitivity characteristics of one or several of these solar cells are changed. From the power yields of these solar cells, which originate from the UV-radiation in the sunlight, the amount of UV- radiation can be evaluated. Preferably, the device comprises one, in particular exactly one such solar cell which is made non-sensitive for visible light by a fil- ter. In another preferred embodiment of the measuring device, the one or several photovoltaic cells which are used as sensor and as generator are photovoltaic cells which are mainly sensitive for UV-radiation. From the power yields of these solar cells, which origin- ate from the UV-radiation in the sunlight, the amount of UV-radiation can be evaluated. Preferably, the measuring device comprises exactly one such photovoltaic cell.

For details of different methods of and devices for evaluating the amount of UV-radiation in sunlight by means of sensors and/or photovoltaic cells, in particular by means of sensors and/or photovoltaic cells which by means of optical filters have been made sensitive to different spectrumS of radiation, it is referred to the prior art identified in the introductory part of the des- cription.

A third aspect of the invention concerns an arrangement comprising a measuring device according to the second aspect of the invention and a receiving unit capable of receiving the data representing the UV-radiation transmitted by the measuring device and of making recognizable the determined UV-radiation. In such arrangements, the advantages of the invention become especially apparent.

In a preferred embodiment of the arrangement, the receiving unit is a mobile phone, preferably a smart phone with an App adapted to make recognizable the determined UV-radiation. Such arrangements are especially convenient in use.

In a further preferred embodiment of the arrangement, the photovoltaic cells of the measuring device, which in the intended operation are used for charging the energy storage, exclusively are photovoltaic cells the power production rate of which mainly depends on the amount of UV-radiation they are exposed to. Furthermore, the measuring device is designed in such a manner that in intended operation the energy storage is charged starting from a defined lower charging level until it reaches a defined upper charging level, and that each time when the energy storage reaches the defined upper charging level, a signal is sent to the receiving unit and the energy storage is set back to the defined lower charging level and the energy storage again is charged by the photovoltaic cell until it reaches the defined upper charging level. The receiving unit in this embodiment of the arrangement is capable of determining the UV-radiation based on the time intervals between the signals received from the measuring device. Such arrangements have the advantage that they can be realized with very simple and robust measuring devices.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings, wherein:

Fig. 1 is a schematic representation of a first arrangement according to the invention;

Fig. 2 is a more detailed schematic representation of the measuring device of the arrangement of Fig. 1;

Fig. 3a is a functional diagram of a first variant of the measuring device of the arrangement of Fig. 1;

Fig. 3b is a functional diagram of a second variant of the measuring device of the arrangement of Fig. 1;

Fig. 4 is a schematic representation of a second arrangement according to the invention;

Fig. 5 is a more detailed schematic representation of the measuring device of the arrangement of Fig.

4; Fig. 6 is a functional diagram of the measuring device of the arrangement of Fig. 4;

Fig. 7 is a schematic representation of a third arrangement according to the invention/

Fig. 8 is a functional diagram of the measuring device of the arrangement of Fig. 7; and

Fig. 9 is a schematic representation of a variation of the arrangements of the Figures 1 to 8.

MODES FOR CARRYING OUT THE INVENTION

Fig. 1 shows a schematic representation of an arrangement 1 according to the invention.

The arrangement 1 comprises a measuring device 2 according to the invention in the form of a button that can be attached to the clothing of a person, which determines the UV-radiation in sunlight, and a receiving unit 3 in the form of a smart phone, which receives from the measuring unit 2 data 4 representing the determined UV-radiation and makes the determined UV-radiation information recognizable.

The data 4 are sent by the measuring unit 2 to the smart phone 3 by Bluetooth in fixed intervals, e.g. every ten seconds.

in a preferred variant, the data 4 is sent by the measuring unit 2 to the smart phone 3 in variable intervals, depending on the available solar energy.

The Smart phone 3 is equipped with an App which, when activated as depicted in Fig. 1, shows the actual UV-radiation intensity 5 in UVI (UV index) , the accumulated amount of UV-radiation 6 in UVIm (UV index minutes) and the course of the UV-radiation intensity 7 in UVI (UV index) for the actual day.

As becomes apparent in synopsis with the Figures 2 and 3a which show a more detailed schematic representation of the measuring device 2 of the arrangement 1 with a part of the side wall removed to show the interior of the device (Fig. 2) and a functional diagram of a first variant of this measuring device 2 (Fig. 3a) , the measuring device 2 comprises two identical photovoltaic cells 8a, 8b which are arranged at the top side of the device 2.

The photovoltaic cells are of type silicon based and are coated on their light absorbing surface with different optical filter coatings 9a, 9b, the first photovoltaic cell 8a with a coating 9a of PTFE (Poly- tetrafluorethylen) , which has a high transitivity for sunlight in the visible spectrum and in the UV spectrum, and the second photovoltaic cell 8b with a coating 9b of acrylic PMMA (Poly-methyl-methacrylate) , which has a high transitivity in the visible spectrum and a sharp cut-off at 400 nm and thus blocks UVA and DVB radiation.

The measuring device 2 further comprises a measuring unit 14 comprising two transimpedance converter 10a, 10b, a differential amplifier 11, an A/D converter 12 and a unit for calculating of UV-radiation 13, by means of which, when the two photovoltaic cells 8a, 8b are exposed to sunlight and thus through their optical filter coatings 9a, 9b receive different radiation spec- trums, from the difference between their short-circuit currents the UV-radiation is determined.

Fig. 3b shows a functional diagram of a second variant of the measuring device 2, which differs from the first variant according to Fig. 3a in that the unit for calculating the UV-radiation 13 does not only receive from the differential amplifier 11 via the A/D converter 12 a signal representing the difference between their short-circuit currents of the photovoltaic cells 8a, 8b but also receives from the two transimpedance converters 10a, 10b via separate A/D converters 12a, 12b signals representing the absolute size of the short- circuit currents of the photovoltaic cells 8a, 8b, which signals it in addition uses to determine the UV- radiation. With the measuring device according to Fig.

3b, which takes into account the intensity of radiation, a more precise determination of the UV-radiation becomes possible than with the measuring device according to Fig .

3a.

Furthermore, the measuring device 2 comprises an energy storage 15, here a ceramic capacitor, for providing the power for its operation, and an electrical circuit with switches S1-S7, which electrical circuit switches the photovoltaic cells 8a, 8b in fixed intervals between a power generating mode, in which the photovoltaic cells 8a, 8b are used as generator for generating electrical power for the device, and a UV-measuring mode, in which the photovoltaic cells 8a, 8b are used as sensor for the measuring unit 14 for determining the UV-radia- tion. In the power generating mode, the photovoltaic cells 8a, 8b by means of the switches S1-S3 are connected in series to the energy storage 15 and the switsches S4-S7 are open, while in the measuring mode the photovoltaic cells 8a., 8b by means of the switches S4-S7 are connected in each case to one of the transimpedance converters 10a, 10b and the switches SI to S3 are open.

Any time the UV-radiation has been determined by the measuring unit 14, data 4 representing the determined UV-radiation are sent by a Bluetooth transmitting unit 16 which is functionally connected with the measuring unit 14 to the smart phone 3 and are made recognize- able by it as has been described hereinbefore.

Fig. 4 shows a schematic representation of a second arrangement according to the invention.

This arrangement 1 differs from the arrangement according to the Figures 1 to 3 in that the UV-radiation is not determined by the measuring unit 2 but is determined by the smart phone 3 based on information 18 received from the measuring unit 2.

As becomes apparent in synopsis with the Figures 5 and 6 which show a more detailed schematic representation of the measuring device 2 of the arrangement 1 with a part of the side wall removed to show the inter- ior of the device (Fig. 5) and a functional diagram of this measuring device 2 (Fig. 6) , the measuring device 2 comprises only one single photovoltaic cell 8 which is arranged at the top side of the device 2.

The power production rate of this photovol- taic cell 8, which is of the type gallium nitride, mainly depends on the amount of UV-radiation it is exposed to. Alternatively, this cell 8 can be a photovoltaic cell 8 sensitive to UV-radiation and to visible light spectrum which is covered by an optical filter that has a high transitivity for UV-radiation and blocks the visible spectrum.

Art energy storage 15 formed by a capacitor, which provides the electrical power for the operation of the measuring device 2, is charged exclusively by this photovoltaic cell 8, and thus only by the energy provided by the UV-radiation in the sunlight.

The measuring device 2 further comprises a Bluetooth transmitting unit 16 and a loading control system 17, which, any time the charging level of the energy storage 15 reached a defined upper charging level, triggers the Bluetooth transmitting unit 16 to transmit a signal 18 to the smart phone 3, and then sets back the energy storage 15 to a defined lower charging level, from which the energy storage 15 is charged again by the photovoltaic cell 8 until it reaches the defined upper charging level .

The smart phone 3 determines, based on the time intervals between the signals IB received by the measuring unit 2, the UV-radiation and makes it recognizable as already described with regard to the first arrangement according to the invention.

Thus, in this arrangement, the single photovoltaic cell 8 is simultaneously used as sensor and as generator.

Fig. 7 shows a schematic representation of a third arrangement according to the invention and Fig. 8 a functional diagram of the measuring device of this arrangement .

This third arrangement differs from the second arrangement according to the Figures 4 to 6 in that within the measuring device 2, the UV-radiation is determined by a unit for calculating .of UV-radiation 13 from the actual power yield of the photovoltaic cell 8 or from the time interval needed for charging the energy storage 15 from a defined lower charging level to a defined upper charging level , Also, as in the first arrangement according to the Figures 1 to 3, data 4 representing the determined UV-radiation are sent by the Bluetooth transmitting unit 16 to the smart phone 3 and are made recognize- able by it as has been described already.

Fig. 9 shows a schematic representation of a variation of the before described arrangements 1. In this variant, the respective arrangement 1 furthermore comprises a central server 18 to which the smart phone 3 transmits data 4 regarding the determined UV-radiation. The central server 18 can also offer means to access cumulative data 6 and exposure over time 7.

Although it is presently shown and described preferred embodiments of the invention, it has to be distinctly understood that the invention is not limited thereto but it may be instead variously embodied and practiced within the scope of the following claims.

Claims

1. Method of measuring the UV-radiation in sunlight by means of a measuring device (2) using one or several photovoltaic cells (8, 8a, 8b) as sensor for determining the UV-radiation, wherein at least a part of said photovoltaic cells (8, 8a, 8b) which are used as sensor furthermore are used as generator for generating electrical power for said measuring device (2) .

2. Method according to one of the preceding claims, wherein the electrical power used by the measuring device (2) is exclusively generated by said one or several photovoltaic cells (8, 8a, 8b) which are used as sensor and as generator.

3. Method according to one of the preceding claims, wherein by means of the measuring device (2), data (4, 18) representing the UV-radiation are transmitted to a receiving unit (3), in particular in wireless manner, ih particular by Bluetooth, by means of which receiving unit (3) the quantity of UV-radiation (5, 6, 7) can be made recognizable or is made recognizable.

4. Method according to claim 3, wherein the data (4, 18) representing the UV-radiation is transmitted to the receiving unit (3) in fixed intervals or in variable intervals, which are depending on the available solar energy.

5. Method according to one of the claims 3 to 4, wherein the data (4, 18) representing the UV-radiation which is transmitted to a receiving unit (3) is in each case determined directly before it is transmitted to the receiving unit (3) .

6. Method according to one of the claims 3 to 5, wherein the receiving unit (3) is a mobile phone, in particular a smart phone (3) with an App adapted to make recognizable the quantity of UV-radiation (5, 6, 7).

7. Method according to one of the preceding claims, wherein the electrical power generated by at least some of said one or several photovoltaic cells (8, 8a, 8b) which are used as sensor and as generator when in use as generator is stored in an energy storage. (15), in particular in a capacitor.

8. Method according to one of the preceding Claims, wherein at least a part of said one or several photovoltaic cells (8a, 8b) which are used as sensor and as generator are temporarily used as sensor and temporarily used as generator.

9. Method according to claim 8, wherein at least a part of said one or several photovoltaic cells (8a, 8b) which are used as senso.r and as generator are alternately, in particular in fixed intervals, used as sensor and as generator .

10. Method according to claim 7 and according to one of the claims 8 to 9, wherein when the energy storage during charging reaches a certain charging level, the use of said one or several photovoltaic cells as generator is stopped and these photovoltaic cells then are temporarily used as sensor for determining the UV- radiation.

11. Method according to claim 10, wherein while said one or several photovoltaic cells are in use as sensor for determining the UV-radiation, the measuring device consumes electrical energy from the energy storage, thereby lowering its charging level .

12. Method according to claim 11, wherein after the determination of the UV-radiation and/or after the charging level of the energy storage has dropped to a certain threshold value, said one or several photovoltaic cells are again used as generator for charging the energy storage.

13. Method according to one of the claims 3 to 6 and according to one of the claims 8 to 12, wherein any time said one or several photovoltaic cells (8, 8a, 8b) have been used as sensor for determining the UV-radiation, data (4) representing the determined UV-radiation are transmitted to the receiving unit (3) .

14. Method according to one of the preceding claims, wherein at least a part of said one or several photovoltaic cells (8) which are used as sensor .and as generator are simultaneously used as sensor and as generator.

15. Method according to claim 7 and according to claim 14,

wherein for charging the energy storage (15), exclusively photovoltaic cells (8) are used the power production rate of which mainly depends on the amount of UV-radiation they are exposed to,

wherein by means of these photovoltaic cells (8) the energy storage (15) is charged starting from a defined lower charging level until it reaches a defined upper charging level,

wherein the time interval needed for charging the energy storage (15) from the defined lower charging level to the defined upper charging level is determined and wherein from the determined time interval the quantity of UV-radiation (5, 6, 7) is evaluated.

16. Method according to claim 15, wherein each time the energy storage (15) reaches the defined upper charging level, the energy storage (15) is set back to the defined lower charging level and the energy storage (15) again is charged by the photovoltaic cells (8) until it reaches the defined .upper charging level .

17. Method according to one of the claims 3 to 6 and according to claim 16, wherein each time the energy storage (15) reaches the defined upper charging level, a signal (18) is send to the receiving unit (3) , and wherein the quantity of UV-radiation (5, 6, 7) is evaluated by the receiving unit (3) based on the time intervals between the signals (18) .

18. Method according to claim 16, wherein each time when the energy storage reaches the defined upper charging level, the quantity of UV-radiation is evaluated by the measuring unit.

19. Method according to one of the claims 3 to 6 and according to claim 18, wherein data representing the evaluated quantity of UV-radiation are transmitted to the receiving unit, in particular each time the quantity of UV-radiation is evaluated or in predetermined inter- vals.

20. Method according to one of the preceding claims, wherein actual UV-radiation values (5) are determined and/or accumulated UV-radiation values (6, 7) over a certain span of time.

21. Method according to one of the preceding claims, wherein said one or several photovoltaic cells (8a, 8b) which are used as sensor and as generator are solar cells which are sensitive for both, UV-radiation and visible light.

22. Method according to claim 21, wherein said solar cells (8a, 8b) are of identical type and wherein part of these solar cells by means of an optical filter (9a, 9b) are made less sensitive or non-sensitive to ov-radiation.

23. Method according to claim 21, wherein pne or several optical filters (9a, 9b) are used to change the sensitivity characteristics of one or several of these photovoltaic cells (8a, 8b) , and in particular, wherein one, in particular exactly one, such photovoltaic cell is used which has been made non-sensitive for visible light by a filter.

24. Method according to one of the claims 1 to 20, wherein said one or several photovoltaic cells (8) which are used as sensor and as generator are photovoltaic cells which are mainly sensitive for UV-radiation, and in particular, wherein exactly one such photovoltaic cell (8) is used.

25. Measuring device (2) for use in the method according to one of the preceding claims, comprising

a) one or several photovoltaic cells (8, 8a,

8b);

b) a measuring unit (13, 14, 17) capable of using the one or several photovoltaic cells (8,

8a, 8b) as sensor for determining UV-radiation, wherein the measuring device (2) is designed in such a manner that the one or several photovoltaic cells (8, 8a, 8b) can be used for both, as generator for generating electrical power for said device (2) and as sensor for said measuring unit for determining the UV-radiation.

26. Measuring device (2) according to claim 25, wherein the measuring device is designed in such a manner that the electrical power used by the measuring device (2) can exclusively be generated by said one or several photovoltaic cells (8, 8a, 8b) which are used as sensor and as generator.

27. Measuring device (2) according to one of the claims 25 to. 26, wherein the measuring device (2) is designed in such a manner that by means of it, data (4, 18) representing the UV-radiation can be transmitted to a receiving unit (3), in particular in wireless manner, in particular by Bluetooth.

28. Measuring Device (2) according to claim 27, wherein the measuring device (2) is designed in such a manner that the data (4, 18) representing the UV-radiation can be transmitted to the receiving unit (3) in. fixed intervals or in variable intervals, which are depending on the available solar energy.

29. Measuring Device (2) according to one of the claims 27 to 28, wherein the measuring device (2) is designed in such a manner that the data (4, 18) representing the UV-radiation which is transmitted to a receiving unit (3) is in each case determined directly before it is transmitted to the receiving unit (3) .

30. Measuring device (2) according to one of the claims 25 to 29, wherein the measuring device (2) comprises an energy storage (15), in particular in the form of one or several capacitors, in which the electrical power generated by at least some of said one or several photovoltaic cells (8, 8a, 8b) which are used as sensor and as generator_, when in use as generator can be stored.

31. Measuring device (2) according to one of the claims 25 to 30, wherein the measuring device (2) is designed in such a manner that at least a part of said one or several photovoltaic cells (8a, 8b) which are used as sensor and as generator can temporarily be used as sensor and can temporarily be used as generator.

32. Measuring device (2) according to claim 31, wherein the measuring device (2) is designed in such a manner that at least a part of said one or several photovoltaic cells (8a, 8b) which are used as sensor and as generator, can alternately, in particular in. fixed intervals, be used as sensor and as generator.

33. Measuring device according to claim 30 and according to one of the claims 31 to 32, wherein the measuring device is designed in such a manner that, when in the intended operation of the device the energy storage during charging reaches a certain charging level, the use of said one or several photovoltaic cells as generator is stopped and these photovoltaic cells then are temporarily used as sensor for determining the UV-radia- tion.

34. Measuring device according to claim 33, wherein the measuring device is designed in such a manner that, while in the intended operation said one or several photovoltaic cells are in use as sensor for determining the UV~radiation, the measuring device consumes electrical energy from the energy storage, thereby lowering its charging level.

35. Measuring device according to claim 34, wherein the measuring device is designed in such a manner that, after the determination of the UV-radiation and/or after the charging level of the energy storage has dropped to a certain threshold value, said one or several photovoltaic_, cells are again used as generator for charging the energy storage.

36. Measuring device (2) according to claim 27 and according to one of the claims 31 to 35, wherein the measuring device (2) is designed in such a manner that in the intended operation any time said one or several photovoltaic cells (8a, 8b) have been used as sensor for determining the UV-radiation, data (4) representing the determined UV-radiation are transmitted to the recei- ving unit (3) .

37. Measuring device (2) according to one of the claims 25 to 36, wherein the measuring device (2) is designed in such a manner that at least a part of said one or several photovoltaic cells (8) which are used as sensor and as generator can simultaneously he used as sensor and as generator.

38. Measuring device (2) according to claim 30 and according to claim 37,

wherein the photovoltaic cells (8) of the measuring device (2) which in the intended operation are used for charging the energy storage (15) exclusively are photovoltaic cells (8) the power production rate of which mainly depends on the amount of UV-radiation they are exposed to,

and wherein the measuring device (2) is designed in such a manner that in intended operation the energy storage (15) can be charged starting from a defined lower charging level until it reaches a defined upper charging level, and the time interval needed for charging the energy storage from the defined lower charging level to the defined upper charging level can be determined.

39. Measuring device (2) according to claim 38, wherein the measuring device (2) is designed in such a manner that in the. intended operation each time when the energy storage (15) reaches the defined upper charging level, the energy storage (15) is set back to the defined lower charging level and the energy storage (15) again is charged by the photovoltaic cells (8) until it reaches the defined upper charging level.

40. Measuring device (2) according to claim 27 and according to claim 39, wherein the measuring device (2) is designed in such a manner that in the intended operation each time the energy storage (15) reaches the defined upper charging level, a signal (18) is sent to the receiving unit (3) .

41. Measuring device (2) according to Claim 38, wherein the measuring device (2) is designed in such a manner that in the intended operation each time when the energy storage (15) reaches the defined upper charging level, the quantity of UV-radiation (5, 6, 7) is evaluated by the measuring unit (13) from the determined time interval needed for charging the energy storage from the defined lower charging level to the defined upper charging level.

42. Measuring device (2) according to claim 27 and according to claim 41, wherein the measuring device (2) is designed in such a manner that in the intended operation data (4) representing the evaluated quantity of UV-radiation (5, 6, 7) can be transmitted to the receiving unit (3) , in particular each time the quantity of UV-radiation (5, 6, 7) is evaluated or in predetermined intervals.

43. Measuring device (2) according to one of the claims 25 to 42, wherein the measuring device (2) is designed in such a manner that in the intended operation it can be used for determining actual UV-radiation values (5.) and/or accumulated UV-radiation values (6, .7) over a certain span of time.

44. Measuring device (2) according to one of the claims 25 to 43, wherein said one or several photovoltaic cells (8a, 8b) of the measuring device (2) which are used as sensor and as generator are solar cells (8a, 8b) which are sensitive for both, UV-radiation and visible light.

45. Measuring device according to claim 44, wherein said solar cells are solar cells of identical type and wherein part of these solar cells by means of an optical filter are made less sensitive or non-sensitive to UV-radiation.

46. Measuring device (2) according to claim 44, wherein the measuring device (2) comprises one or several optical filters (9a, 9b) by which the sensitivity characteristics of one or several of these photovoltaic cells (8a, 8b) are changed, and in particular, wherein the measuring device (2) comprises one, in particular exactly one, such photovoltaic cell which is made nonsensitive for visible light by an optical filter.

47. Measuring device (2) according to one of the claims 25 to 44, wherein said one or several photovoltaic cells (8) of the measuring device (2) Which are used as sensor and as generator are photovoltaic cells (8) which are maiply sensitive for UV-radiation, and in particular, wherein the measuring device (2) comprises exactly one photovoltaic cell (8) which is mainly sensitive for UV-radiation.

48. Arrangement (1) comprising a measuring device (2) according to one of the claims 25 to 47 and a receiving unit (3) capable of receiving the data (4, 18) representing the UV-radiation transmitted by the measure- ing device (2) and of making recognizable the determined UV-radiation (5, 6, 7) .

49. Arrangement (1) according to claim 48, wherein the receiving unit (3) is a mobile phone, in particular a smart phone (3) with an App adapted to make recognizable the determined UV-radiation (5, 6, 7).

50. Arrangement (1) according to one of the claims 48 to 49, wherein the arrangement (1) comprises a measuring device (2) according to claim 36 and wherein the receiving unit (3) is capable of determining the UV- radiation based on the time intervals between the signals (18) received from the measuring device (2) .