GB2427464A

GB2427464A - Mobile telephone featuring an ultra violet detector

Info

Publication number: GB2427464A
Application number: GB0512735A
Authority: GB
Inventors: Richard Collin
Original assignee: Symbian Software Ltd
Current assignee: Symbian Software Ltd
Priority date: 2005-06-22
Filing date: 2005-06-22
Publication date: 2006-12-27
Also published as: GB0512735D0

Abstract

A mobile telephone equipped with a digital camera is provided with Ultra Violet (UV) metering technology so that a user of the device can be provided with an indication of exposure to UV radiation. In one embodiment a fluorescent filter 8 is arranged over the lens of the camera which converts UV radiation 14 in the ambient radiation 10 to visible light 16.

Description

Multifunctional Mobile Computing Device Incorporating a Sun Index Monitor The present invention relates to multifunctional mobile computing devices, and in particular to such a device in the form of a camera phone which is also arranged to function as a sun index and exposure monitor. Ultra-violet (UV) radiation from strong direct sunlight is known to raise certain concerns in relation to human health. The World Health Organisation writes: "The harmful effects of exposure to UV radiation usually far outweigh its benefits. In addition to the well-known short-term effects of overexposure to the sun such as sunburn or allergic reactions, long-term effects pose a life-long hazard to your health. Overexposure to UV radiation affects your skin, your eyes and probably your immune system. Many people forget that the effects of exposure to UV radiation accumulate over a lifetime. Your sun exposure behaviour now determines your chances of developing skin cancer or cataracts later in life! Skin cancer incidence is strongly correlated with the duration and frequency of sun exposure." (from http://www.who.int/uv/faq/uvhealtfac/en/print.html). As well as the above long-term potential effects of overexposure to UV radiation, it is known that even short-term overexposure is the cause of sunburn, which is an uncomfortable and painful condition. This can be especially so for fair skinned persons who live in more northerly regions who normally are not frequently exposed to much strong sunlight, The principal measure to be taken by a person to protect against UV radiation is to avoid direct exposure during periods of strong sunlight. This is generally achieved either by staying in the shade or indoors, or by wearing clothes specifically designed to minimise the penetration of UV radiation, or by the use of chemical sunscreens and sunblocks applied directly to the skin. However, it is also known that the apparent strength of the sun is difficult to assess in terms of potential UV exposure. The radiation from the sun can pass through clouds and can be reflected off many types of surfaces (such as water, concrete, snow), and relying on one's perception of the sun's radiation strength is not a reliable means of evaluating whether prophylactic measures need to be taken. For these reasons, personal UV meters have been developed that are designed to give an accurate reading of the danger; these include the Sunsafe range from Optix Tech Inc., which is described at http://www.safesun.com/ and the XPOSURE Alert+ from Wireless Alarm Products Inc, which is described at http://www.wirelessalarm.com/NU300.htm. The principal concern with personal UV meters is that a user has to remember to carry the dedicated meter on their person when exposure to UV radiation is anticipated. Even when it is remembered to carry the UV meter, current designs have disadvantages. For example, it is difficult to know what the optimum size of this device might be. Of the two devices referred to above, the Optix Tech Sunsafe (about the size of a mobile phone) is bulky enough to compete for space in the pocket, bag or purse, while the Wireless Alarm Products XPOSURE Alert+ device, at 2 square inches, may be a little too large to be conveniently worn. With the present invention is has been realised that a solution to this problem may be provided by incorporating the UV metering technology as additional functionality in an already multifunctional computing device that people are familiar with and are very likely to carry with them as routine, and with which they take a degree of care and are unlikely to forget, leave behind or lose. Thus, according to a first aspect of the present invention there is provided a multifunctional mobile computing device comprising monitoring means for monitoring the level of ultra violet radiation incident on the device. According to a second aspect of the present invention there is provided a method of enabling the detection of UV radiation comprising including a UV metering device in a multifunctional mobile computing device. According to a third aspect of the present invention there is provided an operating system for causing a multifunctional mobile computing device of the first aspect to operate in accordance with a method of the second aspect. Embodiments of the present invention will now be described, by way of further example only, with reference to the accompanying drawings in which:- Figure 1 shows a view of a camera phone having an integral camera incorporating a lens mounted on the rear case portion of the phone body; Figure 2 shows a partial cross sectional schematic side view of a camera phone having a fluorescent dome filter arranged over the integral camera in accordance with the present invention; Figure 3 shows a partial cross sectional schematic side view of a camera phone having a filter which transmits UV radiation arranged over the integral camera in accordance with the present invention;Figure 4 shows a partial cross sectional schematic side view of a camera phone which assesses potential UV exposure in relation to other factors, such as device location; and Figure 5 shows a view of a camera phone having an integral camera and a separate discrete UV radiation detector. With the present invention it is considered that the ideal multifunctional computing device with which to integrate UV metering technology is currently the advanced camera-equipped mobile telephone, as shown in figure 1. Because such a device 2 includes a camera 4 having a lens 6, it already has the capability to detect levels of electromagnetic radiation in or near to the visible spectrum, and because it already includes considerable computing power and a relatively advanced user interface, it is relatively straightforward to provide the software capability needed to interface with a UV detector and provide information to the user as needed. Most importantly, because it is a mobile telephone, it is a ubiquitous mobile computing device as well as a multifunctional one; that is to say, it is one which a large number of people can be relied on to carry with them at most times, indoors and out, both by the young (who are especially vulnerable to UV) and the old. For the young, as an example, it has recently been reported that 98% of teenagers in the United Kingdom now possess and use a mobile phone as routine so the significant benefit and advantage that can accrue by incorporating a UV meter in such a device can be readily appreciated. It should be noted that while the currently preferred implementation of this invention is on mobile telephones, this is because these are currently the most ubiquitous multifunctional mobile computing devices in current use. However, it is to be understood that this invention can be applied to any similarly ubiquitous multifunctional mobile computing device which might become available in the future, and the description here in terms of a mobile telephone implementation is provided for illustration only and is not intended to restrict the applicability of this invention. The current generation of advanced mobile telephones include digital cameras incorporating CCDs (charge coupled devices). According to Oliver Graydon, writing in "Opto & Laser Europe" in February 2003: "At the heart of all CCD cameras is a charge-coupled device (CCD) image chip. This is an array of light-sensitive pixels that are electrically biased so that they generate and store electrons - electric charge when illuminated with light ... the amount of charge trapped beneath each pixel directly relates to the number of photons illuminating the pixel. This charge is then "read out" by changing the electrical bias of an adjacent pixel so that the charge travels out of the sensor, is converted into a voltage and is then digitized into an intensity value." (from http://optics.org/articleslole/8/2/3/1). The use of the CCD that is used in a camera phone to detect UV radiation cannot, however, be regarded as entirely straightforward. According to Andrew Davidhazy of the School of Photographic Arts and Sciences in Rochester, NY 14623, USA: "It is a long standing and well established belief or fact that making photographs by ultraviolet radiation with digital cameras is impossible due to the very low blue and UV sensitivity of CCD image receptors. Unlike the situation with Infrared, where the CCDs are very sensitive and manufacturers have to take pains to make sure to exclude such radiation from reaching the CCD sensor so that its visual response to red, green and blue is not contaminated by infrared, in the UV such precautions are unnecessary." (from "Reflected Ultraviolet Digital Photography with improvised UV image converter" Andrew Davidhazy, available at http:// www.rit.edu/-andpph/text-reflected-uv.html. Davidhazy in fact went on to solve the problem of taking UV digital photographs with an ordinary digital camera; later on in the same paper, he writes: `Almost any substance that fluoresces on exposure to ultraviolet performs the desired task and can be used as the basis for a UV-tovisible converter. So, I took a piece of glass and spray painted it with fluorescent yellow paint. After it dried I covered it with the 18A filter material and then used a lens to form an image of a "black light" lamp through the 18A filter onto the fluorescent paint layer. Sure enough, right through the 18A filter the image of the lamp could be clearly seen.

And, if it could be seen then it followed it could be photographed. Therefore, in a first implementation of this invention, as shown in figure 2, a removable or retractable fluorescent dome 8 or other shaped filter is placed over the lens 6 on the camera phone. The ambient radiation 10 contains light in the visible spectrum 12 as well as UV radiation 14, the exposure to which is required to be measured. The dome 8 screens out all ambient radiation 10 on its outer side but fluoresces on its inner side in response to the UV radiation 14 in the ambient radiation. This produces visible light 16 between the inner surface of the dome and the lens 6 of the mobile telephone 2. The amount of visible light detected by the CCDs located in the telephone in a region behind the lens 6 is then proportional to the level of UV radiation 14 falling on the outer surface of the dome 8. Suitable daylight UV substances that fluoresce on exposure to the UV in normal daylight are commercially available (see, for example, http://www.maxmax.com/aUVPowderUVHG.htm). Each dome, CCD and phone model should be calibrated either by the manufacturer or the user in order to give the user a reliable estimate of the level and consequent risk of UV exposure. A second implementation of this invention is to use a different type of CCD inside the camera phone which is better able to detect UV radiation as well as radiation in the visible spectrum. Such CCDs are now becoming more readily available. One such design is disclosed by Franks, Kriik and Nathan: "Typical polysilicon gate charge-coupled device (CCD) image sensors are unresponsive to ultraviolet (UV) light because of the high absorption of the radiation in polysilcon gate material, which leads to a short penetration depth (2 nm), and absorption of the radiation in the gate material rather than within the channel of the CCD. UV into visible radiation have been developed as a simpler, yet effective solution. For example, Photometrics Ltd. has developed Metachrome II, a sputterdeposited coating based on the organic coronene molecule [8]-[10]. " From "UV-Responsive CCD Image Sensors With Enhanced Inorganic Phosphor Coatings" by Wendy A. R. Franks, Martin J. Kiik, and Arokia Nathan, leee Transactions On Electron Devices, Vol. 50, No. 2, February 2003. More information on this type of CCD technology can be found in "CCD Image Sensors in Deep-Ultraviolet Degradation Behavior and Damage Mechanisms" by Li and Nathan (Springer 2005 ISBN: 3-540-22680-X). Suitable CCDs that are capable of detecting UV are now available commercially. One example is Kodak's KAI-2000DUV. The manufacturers write that the "KAI-2000 Interline CCD image sensor ... is the first Kodak image sensor that captures images in the ultraviolet portion of the light spectrum (200nm-400nm). Image sensors are typically sensitive only to visible wavelengths (400nm-700nm)." From http://www.kodak.com/global/plugins/acrobat/en/digital/ccd/pressRelea ses/DUVInterlinelmager.pdf Hence, in this second embodiment of the invention, a detachable, removable or retractable filter 18 is placed over the lens 6 on the camera phone 2, which cuts out all the visible light 12 in the ambient radiation but allows the UV radiation 14 to pass through and impinge on the lens 6, as shown in figure 3.As with the previous implementation, each filter, CCD and phone model is calibrated either by the manufacturer or the user in order to give the user a reliable estimate of the level and consequent risk of UV exposure. A third embodiment of this invention makes use of known local correlations between the brightness or intensity of the impinging visible light and the amount of UV radiation, as shown in figure 4. In this implementation, a detachable, removable or retractable darkened diffusing dome or filter 20 is arranged over the camera lens to even out and restrict the amount of light hitting the lens 6 and thus the CCD sensors in the phone. The software application driving this functionality on the telephone is arranged to be able to identify the physical location of the telephone; this may be achieved using any positioning technology such as through the use of a Global Positioning System (GPS) unit 22 integral to the phone or the cell ID available to mobile cellular devices, or both.Once the location is determined, the device is able to look up the correlation between the amount of light detected and the level of UV exposure, taking into account factors such as the latitude, the time of day and season of the year, and the condition of the ozone layer. A UV exposure reading is then computed and provided to the user through a display or user interface 26 of the device. The process of looking up the data can be performed by interrogating local tables stored on the device itself or alternatively could be requested from a local or wide network to which the device could be connected. Once again, each dome or filter, CCD and phone model should be calibrated either by the manufacturer or the user in order to give the user a reliable estimate of the level and consequent risk of UV exposure. A practical variation on any of the above embodiments is for the fluorescent barrier, light filter or diffusing filter to be calibrated by the manufacturer and placed inside the camera phone by the manufacturer when the device is built. A user option selected on the telephone would then cause the barrier to slide over the lens whenever a UV exposure reading is required by the user. Alternatively, the device can be arranged so that the filter is by default located over the lens so that the device always can act as a UV meter, and the filter is moved to a position where it does not cover the lens only when the camera function on the telephone is selected by the user. A further implementation of this invention is to include a discrete UV meter 28 (using any UV capable detection technology, including but not limited to UV CCDs) which is separate to the camera CCD but which utilises the inherent computing power on the telephone; this could either be built into the telephone at manufacture, as shown in figure 5, or could be selectively connected postmanufacture by the user. In the latter case the interface may be a wireless one utilising, for example, Bluetooth or infrared technology. However, a semipermanent physical coupling of the UV meter to the phone may be considered preferable, because it minimises the chances of the UV meter being lost, mislaid or forgotten. Optionally, any of the above embodiments could be used to continually monitor the UV exposure of a user and produce alarms or warnings at preset levels of exposure. It can be seen therefore that significant advantages can accrue by providing UV monitoring functionality in a multifunctional mobile computing device. In particular, including a UV sensor capability in a camera phone can warn users of the intensity of and exposure to sunlight, with the attendant (and now widely publicised) potential health benefits. Furthermore, because the mobile phone is typically carried by users as commonplace, this is preferable to using a stand-alone UV meter that is much more likely to be forgotten by a user. Additionally, the computing power of the mobile phone and its programmable user interface enable a high level of functionality to be implemented at very little additional cost with a consequent more easily attainable widespread benefit to both the personal health of the user of the phone and the public health of the wider population. Although the present invention has been described with reference to particular embodiments, it will be appreciated that modifications may be effected whilst remaining within the scope of the present invention as defined by the appended claims.

Claims

Claims:

1. A multifunctional mobile computing device comprising monitoring means for monitoring the level of ultra violet radiation incident on the device.

2. A device according to claim 1 wherein the monitoring means comprises a. a digital camera comprising an aperture and charge coupled devices (CCDs) for detecting radiation in the visible light spectrum; b. a filter for the aperture of the digital camera arranged to fluoresce on an inner surface when exposed to UV radiation and to screen out visible light incident on its outer side; and c. computing means for computing and recording the intensity of the UV radiation by monitoring output signals of the CCDs in response to the fluorescence from the filter.

3. A device according to claim 1 wherein the monitoring means comprises a. a digital camera comprising an aperture and CCDs for reacting to the intensity of UV radiation as well the visible light spectrum; and b. a filter for the aperture of the digital camera arranged to screen out visible light while allowing the passage of UV radiation; and c. computing means for computing and recording the intensity of the UV radiation by monitoring output signals of the CCDs in response to the UV radiation passed by the filter.

4. A device according to claim 1 wherein the monitoring means comprises a. a digital camera comprising an aperture and CCDs for reacting to the visible light spectrum; b. a filter for the aperture of the digital camera arranged to diffuse and restrict the passage of a portion of the visible light spectrum; and c. computing means for computing and recording the intensity of the UV radiation by monitoring output signals of the CCDs in response to the visible light passed by the said filter in combination with other data including but not limited to: i. the location of the device; ii. the time of day and season of the year; iii. the state of the ozone layer; and wherein such other data is either included on the device or obtained by arranging for the device to connect to a local or wide-area or global computer communications network.

5. A device according to any one of claims 2 to 4 wherein the filter comprises a. a detachable filter which is manually placed over the aperture of the digital camera; or b. a filter which is integral to the device and is arranged to be positioned over the aperture of the digital camera either manually or electronically in response either to user input or to a software command.

6. A device according to claim 1 wherein the monitoring means comprises a dedicated detector for detecting the intensity of UV radiation, and software means for receiving and recording the data provided by the monitoring means.

7. A device according to claim 6 wherein the monitoring means is integral to the device.

8. A device according to claim 6 wherein the detector comprises a discrete detector which can be connected to the device either physically or by means of a wireless connection.

9. A device according to any one of the preceding claims which is arranged to continuously monitor UV radiation levels whilst it is in an operational mode.

10.A device according to any one of the preceding claims comprising a user interface arranged to display elements which advise a user of items relevant to his /her health including but not limited to: a. the actual or potential exposure to UV radiation for any period of time; b. an estimate of the maximum safe period of exposure to UV radiation, adjusted for individual skin types and pigmentation.

11. A device according to any one of the preceding claims comprising a mobile telephone.

12.A method of enabling the detection of UV radiation comprising including UV metering device in a multifunctional mobile computing device.

13.A method according to claim 12 wherein the UV metering device is selected to comprise a. a digital camera comprising an aperture and CCDs for reacting to the visible light spectrum; b. a filter for the aperture of the digital camera arranged to fluoresce on an inner surface when exposed to UV radiation and to screen out visible light incident on its outer side; and c. computing means for computing and recording the intensity of the UV radiation by monitoring the output signals of the CCDs in response to the fluorescence from the filter.

14.A method according to claim 12 wherein the UV metering device is selected to comprise a. a digital camera comprising an aperture and CCDs for reacting to the intensity of UV radiation as well the visible light spectrum; and b. a filter for the aperture of the digital camera arranged to screen out visible light while allowing UV radiation pass through; and c. computing means for computing and recording the intensity of the UV radiation by monitoring the output signals of the CCDs in response to the UV radiation passed by the filter.

15. A method according to claim 12 wherein the UV metering device is selected to comprise a. a digital camera comprising an aperture and CCDs for reacting to the visible light spectrum; b. a filter for the aperture of the digital camera arranged to diffuse and restrict the passage of a portion of the visible light spectrum; and c. computing means for computing and recording the intensity of the UV radiation by monitoring the output signals of the CCDs in response to the visible light passed by the said filter and other data included but not limited to: i. the location of the device; ii. the time of day and season of the year; iii. the state of the ozone layer; and wherein such other data is included on the device or is obtained by connecting the device to a local or wide-area or global computer communications network.

16.A method according to any one of claims 13 to 15 wherein the filter is selected to comprise a. a detachable filter which is manually placed over the aperture of the digital camera; or b. a filter which is integral to the device and is arranged to be positioned over the aperture of the digital camera either manually or electronically in response either to user input or to a software command.

17.A method according to claim 12 wherein the metering device is selected to comprise a dedicated detector for detecting the intensity of UV radiation, and software means for receiving and recording the data provided by the monitoring means.

18.A method according to claim 17 wherein the metering device is arranged to be integral to the multifunctional mobile computing device.

19.A method according to claim 17 wherein the metering device is arranged to comprise a discrete detector which can be connected to the multifunctional mobile computing device either physically or by means of a wireless connection.

20. A method according to any one of claims 12 to 19 wherein the metering device continuously monitors UV radiation levels whilst the multifunctional mobile computing device is in an operational mode.

21. A method according to any one of claims 12 to 20 wherein the multifunctional mobile computing device is selected to comprise user interface elements which advise a user of items relevant to his/her health including but not limited to: a. actual or potential exposure to UV radiation for any period of time; b. an estimate of the maximum safe period of exposure to UV radiation, adjusted for individual skin types and pigmentation.

22.A method according to any one of claims 12 to 21 wherein the multifunctional mobile computing device is selected to comprise a mobile telephone.

23.An operating system for causing a multifunctional mobile computing device to operate in accordance with a method as claimed in any one of claims 12 to 22.