ELECTRONIC DEVICE, IN PARTICULAR MOBILE TELEPHONE, FOR DETECTING RADIATION

Abstract

The invention relates to an electronic device, in particular a mobile telephone (1), comprising an image sensor (4) with multiple pixels for capturing an image. The image sensor (4) is also sensitive to ionizing radiation, in particular pulsed high-energy radiation. The invention additionally relates to a radiation sensor (5) for measuring the ionizing radiation.

Description

The invention concerns an electronic device, in particular a mobile phone, according to the main claim.

Modern mobile phones often possess an integrated digital camera for capturing images or films. For this purpose, the integrated digital camera has an image sensor (e.g. CCD sensor or CMOS sensor) with numerous image elements (pixels) arranged in the form of a matrix. Hitherto, such mobile phones with an integrated digital camera have, however, still not been used for measurement of ionizing radiation.

Therefore, the invention is based on the object of using a mobile phone with an integrated image sensor also for measurement of ionizing radiation.

This object is achieved by means of a corresponding mobile phone according to the main claim.

The invention is based at first on the technical-physical insight that the image sensor often integrated in modern mobile phones are not only sensitive to visible light, but also allows the measurement of ionizing radiation, in particular pulsed high-energy radiation, as occurs, for example, with computer tomographs (CTs).

The invention therefore comprises the general technical teaching to use the image sensor in such a mobile phone or in any other electronic device with such an image sensor also for measurement of ionizing radiation. The technical realization of this idea is described in the subsequently published patent application PCT/EP2001005353, so that, to avoid repetition, reference is made to this patent application.

Furthermore, the invention provides an additional radiation sensor in order to measure the ionizing radiation, wherein it can be, for example, a conventional Geiger-Müller counter tube or a photodiode (e.g. a PIN photodiode) (PIN: Positive Intrinsic Negative). The invention therefore preferably provides the combination of a conventional image sensor (e.g. CCD sensor, CMOS sensor) with a radiation sensor (e.g. Geiger-Müller counter tube, PIN photodiode), so that the ionizing radiation is measured with two different sensors, which is associated with different advantages, which will be described in detail below.

Alternatively, there is also the option that several image sensors are combined with one another in order to allow a radiation measurement as accurate as possible, wherein a separate radiation sensor can be dispensed with.

At this point, it is to be mentioned that the electronic device does not necessarily have to be a mobile phone. The invention rather comprises also other types of electronic devices, which have an integrated image sensor and which are additionally equipped within the context of the invention with a radiation sensor.

In a preferred exemplary embodiment of the invention, the electronic device has an evaluation unit, which is connected on the input side with the image sensor and with the radiation sensor and calculates from the output signals of the image sensor and of the radiation sensor a radiation value (e.g. dosage value, dose rate value), which reflects the ionizing radiation.

On the one hand, the evaluation unit detects the pixel values of the individual image elements (pixels) of the image sensor and calculates therefrom, in the framework of a statistical evaluation, a corresponding radiation value. The technical details of this evaluation of the individual pixel values are described in the above-mentioned patent application, whose content is therefore to be included in full in the present description.

On the other hand, the evaluation unit receives a radiation value from the radiation sensor (e.g. Geiger-Müller counter tube, PIN photodiode).

The evaluation unit can then compare, within the context of the invention, the radiation values measured by the image sensor and the radiation sensor with one another.

The combination of an image sensor with a radiation sensor for radiation measurement is advantageous because an image sensor on the one hand and a radiation sensor on the other hand generally have different spectral measurement ranges. This means that the image sensor and the radiation sensor are generally sensitive to radiation with different wavelengths resp. frequencies.

Furthermore, there is within the context of the invention the option that the image sensor and the radiation sensor have different power measurement ranges. The radiation sensor (e.g. Geiger-Müller counter tube) can thus, for example, serve for measurement of lower radiation performances, whereas the image sensor serves for measurement of high radiation performances.

For example, the image sensor can have a measurement range, which extends to high radiation performances up to the kilosievert range, whereas the radiation sensor can have a measurement range, which can extend to low radiation performances up to the nanosievert range. The image sensor can therefore measure higher radiation, whereas the radiation sensor can measure lower radiation.

The combination of an image sensor with a radiation sensor for measurement of ionizing radiation is also advantageous because such sensors generally use different methods of measurement, thus creating redundancy.

Beyond this, the image sensor and the radiation sensor can be sensitive to different types of radiation (e.g. alpha radiation, beta radiation, gamma radiation).

In an exemplary embodiment of the invention, the image elements of the image sensor are at least partially covered with attenuators, wherein the attenuators attenuate the incident ionizing radiation. Such attenuators can, for example, be layer-wise and made of copper, aluminium, lead or plexiglass. The thickness of the attenuators varies in this case preferably between the individual image elements (pixels) of the image sensor, which allows for a corresponding statistical evaluation a highly accurate determination of the spectral energy distribution of the incident ionizing radiation. For example, the attenuators can have a thickness, which expands wedge-shaped from a side of the image sensor to the opposite side of the image sensor, so that the incident ionizing radiation is attenuated on the one side of the wedge-shaped attenuator only slightly, whereas the incident ionizing radiation on the opposite side of the wedge-shaped attenuator is attenuated essentially stronger.

Such attenuator can be used within the context of the invention also for the radiation sensor.

Moreover, a radiation filter can be arranged in the radiation path of the radiation sensor and/or of the image sensor.

It should also be mentioned that the measuring sensitivity of the image sensor is generally temperature-dependent. In a preferred exemplary embodiment of the invention, a temperature sensor is therefore provided for in order to detect the temperature of the image sensor and/or of the radiation sensor. The evaluation unit then takes into account the temperature of the image sensor measured by the temperature sensor in order to compensate for the temperature fluctuations during the measurement.

Moreover, the electronic device according to the invention can additionally have an active cooling element (e.g. a Peltier element) in order to actively cool the image sensor and thereby to increase the measuring sensitivity of the image sensor. Triggering of the active cooling element can in this case take place depending on the measured temperature of the image sensor in the framework of a control operation or a feedback control.

Furthermore, a converter (e.g. a scintillator) can be arranged in the radiation path of the image sensor and/or of the radiation sensor, which converter converts the incident radiation from a badly detectable wavelength range into a better detectable wavelength range. The application of such a converter therefore allows the measurement of incident radiation in a wavelength range, in which the image sensor resp. the radiation sensor is insensitive.

During read-out of the image sensor, the problem can occur that the image sensor has a short dead time, so that no radiation measurement is possible within the dead time. During the measurement of pulsed radiation, there is, however, the option that the individual radiation pulse each fall in the dead time of the image sensor, so that the incident radiation is not detected.

To avoid such read-related dead times, it is provided for in a variant of the invention that several image sensors are combined with one another. This has the advantage that the dead time of the individual image sensor generally has no temporal overlap, so that at least one of the image sensors is sensitive at any time and allows radiation measurement.

Another solution to this problem of the dead times of image sensors consists in the application of the so-called ERS technology (ERS: Electronic Rolling Shutter). In this process, the individual image elements (pixels) of the image sensor are each scanned and saved line by line, so that the image sensors are each insensitive only in a single line, whereas the other lines of the image sensor are sensitive and then allow a radiation measurement. In this manner, in particular for the measurement of pulsed radiation, it is prevented that the image sensor is fully insensitive to a radiation pulse.

During the radiation measurement, it must be taken into account that the measurement result depends on the alignment of the respective radiation sensor and on the positioning of the radiation sensor. So, for example, the user of a mobile phone with an integrated radiation sensor can shadow off the radiation sensor with his body, whereby the radiation sensor measures a falsified radiation value. In a variant of the invention, the device that serves for radiation measurement therefore has several radiation sensors, which are spatially arranged in a distributed manner and/or are oriented in different directions. The evaluation unit can then evaluate the output signals of the different radiation sensor in order to suppress disturbance variables.

Beyond this, there is the option that the radiation sensor can be oriented in the device in different directions relative to the device, wherein the spatial orientation of the radiation sensor in operation can be changed. For example, a servomotor can be provided for this purpose, which orientates the radiation sensor in the desired direction.

Furthermore, there is also within the context of the invention the option that several image sensors are combined with one another in order to allow a radiation measurement as accurate as possible, wherein a separate radiation sensor can also be dispensed with. This is essential for a spectral measurement. For example, the second image sensor can be covered partially or fully by a scintillator. Furthermore, there is the option to combine a radiation sensor with several image sensors.

The device for radiation measurement according to the invention is suitable in particular for the measurement of the radiation exposure for airplane crews, which are exposed to a significant cosmic radiation, in particular during long-haul flights. The invention therefore also comprises a flying object, such as an aircraft or a space vehicle, with an electronic device for radiation measurement according to the invention.

Other advantageous developments of the invention are characterized in the sub-claims or are explained in more detail below together with the description of the preferred exemplary embodiment of the invention on the basis of the figures. The figures show as follows:

FIG. 1 a front view of a mobile phone with an integrated digital camera according to the invention and a likewise integrated radiation sensor,

FIG. 2 a schematic block diagram of the components of the mobile phone from FIG. 1 serving for radiation measurement,

FIG. 3 a schematic cross-section representation of the image sensor of the mobile phone from FIG. 1,

FIGS. 4a, 4b the radiation measurement method of the mobile phone in the form of a flow chart.

FIG. 1 shows a front view of a mobile phone 1, which is structured to a great extent conventionally and has inter alia a LCD display 2, a loudspeaker 3, an image sensor 4 in the form of a digital camera as well as, additionally, a radiation sensor 5 in the form of a PIN photodiode. Apart from the radiation sensor 5, the mobile phone 1 corresponds to the prior art, so that a detailed description of the structure and mode of operation of the conventional constituent elements of the mobile phone 1 can be dispensed with.

The image sensor 4 serves, in addition to the conventional capturing of images or films, for the measurement of a radiation value of an ionizing radiation in conjunction with the radiation sensor 5, as will be explained below with reference to the schematic block diagram in FIG. 2.

So, the image sensor 4 has a plurality of image elements (pixels), which are arranged in the form of a matrix in lines and columns and deliver a digital image. The individual pixel values of the individual image elements of the image sensor 4 are fed to a statistics unit 6, which calculates a radiation value D₁ within the context of a statistical evaluation of the image values of the individual image elements (pixels) of the image sensor 4, wherein, for example, the radiation value can be the dose energy or the dose rate of the incident radioactive radiation.

The radiation sensor 5 (e.g. PIN photodiode) likewise calculates a corresponding radiation value D₂, wherein both radiation values D₁ and D₂ are supplied to a computing unit 7, which determines a uniform radiation value D and then transmits it via a phone module 8 (e.g. GSM module: Global System for Mobile Communications) and an antenna 9 to a central monitoring device, which then evaluates the radiation values D provided by a plurality of such mobile phones 1.

Moreover, the mobile phone 1 still has a GPS module 10 (GPS: Global Position System), which determines the geographical position of the mobile phone 1 with the help of the satellite-based GPS navigation system. The geographical position of the mobile phone 1 determined in this manner is then likewise transmitted together with the radiation value D via the phone module 8 and the antenna 9 to the central monitoring device. The central monitoring device can then create a radiation map by means of the value pairs transmitted by the numerous mobile phones 1 from the radiation value D and the associated geographical position of the respective mobile phone 1, which radiation map reflects the geographical distribution of the radiation value.

For the radiation measurement, the mobile phone 1 takes into account the temperature dependency of the measurement through the image sensor 4. The mobile phone 1 therefore has a temperature sensor 11, which measures the temperature of the image sensor 4 and transmits a corresponding temperature value T_CCD to the computing unit 7. The computing unit 7 then compensates for any fluctuations of the temperature value T_CCD when determining the radiation value D in order to allow a determination of the radiation value D as temperature-independent as possible.

Moreover, the temperature value T_CCD measured by the temperature sensor 11 is supplied to an actuator 12, which controls a cooling element 13 (e.g. a Peltier element) in such a way that the cooling element 13 acts with a certain refrigerating power P_COOL onto the image sensor 4 in order to maintain the temperature value T_CCD of the image sensor 4 as constant as possible and thereby to avoid temperature-related measurement inaccuracies to the greatest possible extent.

FIG. 3 shows a schematic cross-section through a modification of the image sensor 4 in a housing of the mobile phone 1. For this modification, a wedge-shaped attenuator 14 is arranged in the radiation path before the image sensor 4, the thickness of which enlarges wedge-shaped from a side of the image sensor 4 to the opposite side of the image sensor 4. The attenuator 14 is, for example, made of copper, aluminium, lead or plexiglass and attenuates the incident radioactive radiation depending on the respective thickness of the attenuator 14 more or less, which allows a spectral evaluation of the incident radioactive radiation. So, the image elements (pixels) of the image sensor 4 on the right side in the drawing primarily measure radioactive radiation with a relative high energy, which is sufficient to penetrate the layer of the attenuator 14 on this relatively thick side. On the left side in the drawing, the image elements of the image sensor 4 measure, in contrast, also low-energy radiation, since the attenuator 14 is very thin there.

The FIGS. 4a and 4b show the operating method according to the invention for the mobile phones 1.1-1.4 in the form of a flow chart, wherein only the process steps are represented and described, with which the evaluation unit 7 determines the radiation value D₁ in conjunction with the statistics unit 6 from the pixel values of the image sensor 4.

At first, the drawings show an image sensor 15 with numerous image elements arranged in the form of a matrix for radiation measurement. The image sensor 15 can, for example, be a CCD sensor or a CMOS sensor.

A step 16 comprises a value entry of the images measured by the image sensor 15 with a frame rate of 40-60 fps (frames per second). Alternatively, a frame rate of 15-24 fps is, for example, also possible. Optionally, single images are also possible, then if necessary with shutter times, which correspond to partial image capturing, or conversely time exposures with pretty large shutter times.

The measured images are then saved in a step 17 in an image memory.

Subsequently, in a step 18, a differentiation takes place between the actual image saved in step 17 and a reference image saved a in a step 19, wherein a reference memory contains an average brightness per image element (pixel) from the previous captured images. The thus reached averaging can take place depending on the actual difference, for example according to the following formula:

Ref=Ref·n+new pixel·m(n+m)

• with
• Ref: brightness of the reference image
• n: weighting factor for taking into account the reference image with n+m=1
• m: weighting factor for taking into account the new image with n+m=1
• new pixel: brightness of the new image

The difference thus determined is then compared in a step 20 with an upper limit value and a lower limit value, wherein a counting event is triggered when the measured difference value lies between the upper limit value and the lower limit value.

Optionally, there is the option of a memory 21 for pixel noise represented in FIG. 4b, which is filled in a calibration process 22 with the noise values per pixel. To do so, several measurements are carried out in the dark and without any additional radiation. The individual differences between the current image and the last image are added up with a matrix (noise values per pixel) and then e.g. maximum values resp., after statistical evaluation, the determined values are saved (Gaussian distribution taking into account the incident background radiation). Furthermore, an external threshold 23 can be added, which is added up to the pixel threshold from the memory 21 in a step 24, which provides for more stable results.

A threshold value comparison 25 then provides an analogue or digital signal when threshold values are exceeded resp.—in case of negative sign—fallen short of. In a step 26, the counting events are then added up over a certain unit of time.

Thereupon, in a step 27, the number of counting events (counts) is calculated per minute.

Via a calibration table 28, the assignment to a dose rate (e.g. based on the counts per minute) resp. dose (from the total number of counts) is then created. The calibration table can be created for a group of sensors or created individually through a measurement process with calibrated radiation source. Optionally, a correction factor can be provided for simplified calibration with one or two points.

As a result, in a step 29, a dose rate and, in a step 30, a dose is then output.

Furthermore, there is also the option for an image processing 31 for determining the energy value of the incident photons. Thus, low-energy photons generally trigger only a counting event in a single image element of the image sensor 4. High-energy photons lead in contrast to a crosstalk between neighboring image elements of the image sensor 4, so that a group (cluster) of several neighboring image elements of the image sensor 4 trigger a counting event. Through the image processing 31, such groups of activated image elements can then be determined, whereby a spectral distribution can be calculated in an approximate manner. The values thus obtained are compared with a data base 32 of the energy values, whereupon a spectrum of the incident radiation is then output in a step 33.

The invention is not limited to the previously described preferred exemplary embodiment. Instead, many variants and modifications are possible, which also make use of the concept of the invention and thus fall within the scope of protection. Furthermore, the invention also claims protection for the subject matter and the individual features of the subclaims independently of the features of the claims to which they each refer.

LIST OF REFERENCE SIGNS

• 1 Mobile phone
• 2 LCD display
• 3 Loudspeaker
• 4 Image sensor
• 5 Radiation sensor
• 6 Statistics unit
• 7 Computing unit
• 8 Phone module
• 9 Antenna
• 10 GPS module
• 11 Temperature sensor
• 12 Actuator
• 13 Cooling element
• 14 Attenuator
• 15 Image sensor
• 16 Step “Value entry”
• 17 Step “Save”
• 18 Step “Differencing”
• 19 Step “Reference image”
• 20 Step “Threshold value testing”
• 21 Memory for pixel noise
• 22 Calibration process
• 23 External threshold
• 24 Step “Summation”
• 25 Threshold value comparison
• 26 Step “Summing-up per unit of time”
• 27 Step “Counts per minute”
• 28 Calibration table
• 29 Output Dose rate
• 30 Output Dosage
• 31 Image processing
• 32 Database of the energy values
• 33 Output Spectrum
• T_CCD Temperature value of the image sensor
• D1 Radiation value
• D2 Radiation value
• D Radiation value

Claims

1-20. (canceled)

21. An electronic device comprising:

a) an image sensor with several image elements for capturing an image, wherein the image sensor is also sensitive to ionizing radiation, and

b) at least one of an additional radiation sensor and an additional image sensor adapted for measurement of the ionizing radiation.

22. The electronic device according to claim 21, wherein the device further comprises an evaluation unit, which is connected on an input side with the image sensor and with the additional radiation sensor and calculates a radiation value from output signals of the image sensor and output signals of the additional radiation sensor, which value reflects the ionizing radiation.

23. The electronic device according to claim 22, wherein the evaluation unit statistically evaluates the output signals of the image elements of the image sensor.

24. The electronic device according to claim 22, wherein the evaluation unit compares the output signals of the image sensor with the output signals of the additional radiation sensor.

25. The electronic device according to claim 21, wherein the image sensor is a CCD sensor or a CMOS sensor.

26. The electronic device according to claim 21, wherein the additional radiation sensor is a Geiger-Müller counter tube or a photodiode.

27. The electronic device according to claim 21, wherein the image sensor and the additional radiation sensor have different spectral measurement ranges.

28. The electronic device according to claim 21, wherein the image sensor and the additional radiation sensor have different power measurement ranges.

29. The electronic device according to claim 27, wherein the image sensor has during the measurement of the ionizing radiation a measurement range, which extends into a kilosievert range.

30. The electronic device according to claim 27, wherein the additional radiation sensor has during the measurement of the ionizing radiation a measurement range, which extends into a nanosievert range.

31. The electronic device according to claim 21, wherein the image sensor and the additional radiation sensor apply different measurement methods to create redundancy.

32. The electronic device according to claim 21, wherein the image sensor and the additional radiation sensor are sensitive to different types of radiation of the ionizing radiation.

33. The electronic device according to claim 21, wherein the image elements of the image sensor and/or of the additional radiation sensor are covered at least partially by an attenuator, which is adapted to attenuate incident ionizing radiation.

34. The electronic device according to claim 33, wherein the attenuator is adapted to attenuate the incident radiation to a different degree.

35. The electronic device according to claim 34, wherein the attenuator has a thickness, which extends wedge-shaped from a side of the image sensor adjacent the additional radiation sensor to an opposite side of the image sensor opposite the additional radiation sensor.

36. The electronic device according to claim 33, wherein the attenuator comprises at least one of the following materials:

a) copper,

b) aluminium,

c) lead, and/or

d) polymethyl methacrylate.

37. The electronic device according to claim 33, wherein

a) attenuators of the individual image elements of the image sensor have different spectral attenuation characteristics, and

b) the evaluation unit calculates from output signals of the individual image elements of the image sensor a spectral energy distribution of incident ionizing radiation.

38. The electronic device according to claim 21, wherein a radiation filter is arranged in a radiation path of the additional radiation sensor.

39. The electronic device according to claim 21, wherein

a) the device has a temperature sensor adapted for measurement of a temperature of the additional radiation sensor and/or of the image sensor, and

b) the evaluation unit is connected on an input side with the temperature sensor and takes the measured temperature into account for calculation of a radiation value in order to compensate for temperature fluctuations.

40. The electronic device according to claim 21, further comprising an active cooling element adapted for active cooling of the image sensor in order to increase a measuring sensitivity of the image sensor.

41. The electronic device according to claim 21, wherein a converter is arranged in a radiation path of the image sensor and/or of the additional radiation sensor, which converter is adapted to convert incident radiation from a badly detectable wavelength range into a better detectable wavelength range in order to extend a measurement range.

42. The electronic device according to claim 21, wherein a combination of several image sensors is provided for to avoid dead time due to reading-out.

43. The electronic device according to claim 21, wherein the image sensor has numerous image lines each of which comprises several image elements, wherein the image sensor is adapted to scan and save the image line by line, so that the image sensor is insensitive each time only in a single line.

44. The electronic device according to claim 21, wherein several additional radiation sensors are spatially arranged in a distributed manner and/or are oriented in different directions.

45. The electronic device according to claim 21, wherein the image sensor can be aligned in different directions relative to the device.

46. The electronic device according to claim 45, wherein a servomotor is provided for motorized alignment of the image sensor.

47. The electronic device according to claim 21, wherein, in addition to the image sensor, several different additional radiation sensors are provided for.

48. The electronic device according to claim 47, wherein the different additional radiation sensors are Geiger-Müller counter tubes.

49. The electronic device according to claim 47, wherein the different additional radiation sensors are photodiodes.

50. A flying object with an electronic device according to claim 21 for measurement of radiation exposure of a crew of the flying object through cosmic radiation.

51. The flying object according to claim 50, wherein the flying object is an aircraft.

52. The flying object according to claim 50, wherein the flying object is a spacecraft.

53. The electronic device according to claim 21, wherein the image sensor is sensitive to ionizing radiation which is pulsed radiation up to a kilosievert range.