Display device and method for operating a display device

Abstract

A display device (20) is provided, the display device (20) comprising a display (21) with a first side (22) and a second side (23), the first side (22) facing away from the second side (23), an ambient light sensor (24) arranged at the second side (23) of the display (21), an optical sensor (25) arranged at the second side (23) of the display (21), wherein the optical sensor (25) comprises a plurality of photodetectors (26), and a calculation unit (27), wherein the ambient light sensor (24) is configured to obtain sensor data comprising the irradiance of electromagnetic radiation reaching the ambient light sensor (24), the optical sensor (25) is configured to determine the angle of incidence of at least a part of electromagnetic radiation reaching the optical sensor (25), the calculation unit (27) is configured to correct the sensor data based on the angle of incidence determined by the optical sensor (25) to obtain a corrected irradiance, and the calculation unit (27) comprises a memory (40) in which the transmission coefficient of the display (21) is stored for different angles of incidence. Furthermore, a method for operating a display device (20) is provided.

Description

[0001] 1

[0002] Description

[0003] DISPLAY DEVICE AND METHOD FOR OPERATING A DISPLAY DEVICE

[0004] A display device and a method for operating a display device are provided .

[0005] Ambient light sensors are employed in a wide range of applications . Increasingly, it is desired to integrate sensors such as ambient light sensors in mobile devices behind a screen . In this way, the area occupied by the screen can be maximised . The ambient light sensor can be employed for brightness and color correlated temperature measurements . The detected irradiance , this means the total quantity of incoming radiation, however is influenced by the angle of incidence of incoming light and by apertures above the ambient light sensor, for example within the display . Thus , for example tilting of a device with the ambient light sensor has an impact on the measurement of the irradiance .

[0006] It is an obj ective to provide a display device that can be operated with an improved accuracy . It is further an obj ective to provide a method for operating a display device that can be operated with an improved accuracy .

[0007] These obj ectives are achieved by the subj ect matter of the independent claims . Further developments and embodiments are described in dependent claims .

[0008] According to at least one embodiment of the display device , the display device comprises a display with a first side and a second side , the first side facing away from the second side . The display can comprise a plurality of light-emitting - 2 - pixels. For example, the pixels are configured to independently emit red, green and blue light. Thus, the display can be configured for displaying picture content at the first side of the display. The picture content is, for example, an image, a video, or a hologram. The image or the video could either be a two-dimensional or also a three- dimensional representation, like a stereoscopic representation. The first side can be a front side. The second side can be a back side. The display can have a transmittance for visible light of at least 0.1% or of at least 0.4% or at least 1.0%. Alternatively or additionally, said transmittance is at most 5% or is at most 3% or is at most 2%. Said transmittance may be averaged across the whole display .

[0009] According to at least one embodiment of the display device, the display device comprises an ambient light sensor arranged at the second side of the display. The ambient light sensor can comprise several or a plurality of photodiodes. The photodiodes can each be configured to measure an irradiance of electromagnetic radiation reaching the respective photodiode. Another expression for irradiance is flux density. The irradiance is given in W / m2. From the irradiance it is also possible to determine the illuminance which is given in lux. On at least some of the photodiodes an optical filter can be arranged. At least some of the optical filters can be different from each other. Thus, the ambient light sensor can be a spectral sensor. The spectral information obtained with the ambient light sensor can be used, for example, for supporting display management and automatic white balance of camera systems. The optical filters may be interference filters such as an optical cut-off filter, bandpass, long or short pass filters, dielectric filters, - 3 -

[0010] Fabry-Perot filters, plasmonic filters, meta structure filters and / or polymer filters.

[0011] The ambient light sensor can be a single-channel sensor. For example, the ambient light sensor is a so-called Y-sensor. A Y-sensor is configured to measure the y-coordinate in the CIE xyz-chromaticity diagram. That is, the ambient light sensor may be sensitive in the green spectral range, especially around 555 nm. A spectral sensitivity of the ambient light sensor may accordingly correspond to the CIE's color matching function for green light.

[0012] The ambient light sensor can be a three-channel sensor. For example, the ambient light sensor has one channel for red light, one channel for green light and one channel for blue light. By way of example, the ambient light sensor is a XYZ- sensor measuring the blue, green and red coordinates in the CIE xyz-chromaticity diagram. The channels may thus have spectral sensitivities corresponding to the CIE's color matching functions for blue, green and red light, respectively. Instead of one ambient light sensor having three channels it is equivalently possible to have three different ambient light sensors for blue, green and red light, respectively.

[0013] The ambient light sensor can be a multi-channel sensor. For example, the ambient light sensor has at least five or at least eight or at least ten color channels.

[0014] The ambient light sensor can be arranged in a sensing cavity within the display device. The sensing cavity can have a sensing aperture. The sensing aperture can be arranged between the display and the ambient light sensor. 4

[0015] According to at least one embodiment of the display device , the display device comprises an optical sensor arranged at the second side of the display, wherein the optical sensor comprises a plurality of photodetectors . The photodetectors can each be configured to measure an irradiance of electromagnetic radiation reaching the respective photodetector . Another expression for irradiance is flux density . The irradiance is given in W / m2. From the irradiance it is also possible to determine the illuminance which is given in lux . The optical sensor can be arranged in a sensor cavity in the display device . The sensor cavity can be separate from the sensing cavity . That can mean that there is no direct connection between the sensor cavity and the sensing cavity . The sensor cavity can have a sensor aperture . The photodetectors can be arranged in a two-dimensional array .

[0016] According to at least one embodiment of the display device , the display device comprises a calculation unit . For example , the calculation unit is software stored in a memory and running on a processor of the display device . The processor may run a plurality of applications or programs so that the processor may not exclusively be assigned to the calculation unit . Otherwise , there can be a distinct processor solely configured for carrying out the actions of the calculation unit . The calculation unit may comprise a processor . A computer program to carry out the necessary steps can be stored in a storage device of the calculation unit . The calculation unit may be a computer program . The calculation unit may also include control means to control the display, the optical sensor and / or the ambient light sensor . 5

[0017] According to at least one embodiment of the display device the ambient light sensor is configured to obtain sensor data comprising the irradiance of electromagnetic radiation reaching the ambient light sensor .

[0018] According to at least one embodiment of the display device the optical sensor is configured to determine the angle of incidence of at least a part of electromagnetic radiation reaching the optical sensor . Electromagnetic radiation from one radiation source can be imaged by the optical sensor through the sensor aperture . That can mean, that electromagnetic radiation from one radiation source can be proj ected to the optical sensor through the sensor aperture . That can mean, that the optical sensor with the sensor aperture can be regarded as a pinhole camera . Electromagnetic radiation from one radiation source creates an image behind the aperture that depends on the angle of incidence of the electromagnetic radiation from the radiation source . For example , i f the angle of incidence is di f ferent from 0 ° , not all photodetectors of the optical sensor are illuminated . From the pattern of photodetectors that are illuminated, the angle of incidence of the electromagnetic radiation can be determined . As this principle of determining the angle of incidence is based on detecting electromagnetic radiation from one radiation source , the optical sensor is configured to determine the angle of incidence of at least a part of electromagnetic radiation reaching the optical sensor . This part can be electromagnetic radiation from one radiation source . The radiation source can be a dominant source , as for example the sun . That can mean that the intensity of electromagnetic radiation emitted by the dominant source is higher than the intensity of other electromagnetic radiation reaching the optical sensor . - 6 -

[0019] The angle of incidence refers to the angle between an axis that extends perpendicular to a main plane of extension of the optical sensor and the main propagation direction of electromagnetic radiation reaching the optical sensor .

[0020] The optical sensor can additionally or alternatively be configured to determine the chief ray angle of electromagnetic radiation reaching the optical sensor . The chief ray angle refers to the angle of incidence of electromagnetic radiation with the largest intensity . For example , within the electromagnetic radiation reaching the optical sensor, electromagnetic radiation from a dominant radiation source has the highest intensity . In this case , the chief ray angle refers to the angle of incidence of electromagnetic radiation from the dominant source reaching the optical sensor .

[0021] According to at least one embodiment of the display device the calculation unit is configured to correct the sensor data based on the angle of incidence determined by the optical sensor to obtain a corrected irradiance . The correction is based on the fact that the transmission of electromagnetic radiation through the display depends on the angle of incidence and is influenced by the properties of the display . The correction of the sensor data can thus refer to a removal of the influence of the display on the measurement of the ambient light sensor . The correction of the sensor data can additionally refer to a removal of the influence of the angle of incidence of electromagnetic radiation reaching the display .

[0022] According to at least one embodiment of the display device the calculation unit comprises a memory in which the - 7 - transmission coef ficient of the display is stored for di f ferent angles of incidence . This can mean, that a database is stored in the memory, wherein the database comprises the transmission coef ficient of the display for a plurality of di f ferent angles of incidence . The angles of incidence can be angles of incidence of electromagnetic radiation from a dominant radiation source reaching the display . The transmission coef ficients of the database can be determined in a calibration phase .

[0023] The transmission coef ficients stored in the memory can be employed for the correction of the sensor data . For correcting the sensor data, the transmission coef ficient for the angle of incidence determined by the optical sensor may be obtained from the memory . With the obtained transmission coef ficient , the influence of the display on the measurement of the ambient light sensor can be removed . For example , for the correction of the sensor data, the sensor data is multiplied with a correction factor stored in the memory . The result of the multiplication is a value for the irradiance that would be measured by the ambient light sensor, i f the display was not present . This value can be the corrected irradiance .

[0024] For obtaining the corrected irradiance , it is additionally possible to remove the influence of the angle of incidence of electromagnetic radiation reaching the display . Typically, the irradiance-versus-angle-of-incidence curve follows the shape of a cosine function . A cosine compensation factor can be determined to remove the influence of the angle of incidence from the measurement of the ambient light sensor . The cosine compensation factor is equal to 1 over the cosine of the angle of incidence . Alternatively, the cosine 8 compensation factor is equal to 1 over the cosine of the chief ray angle .

[0025] According to at least one embodiment of the display device , the display device comprises a display with a first side and a second side , the first side facing away from the second side , an ambient light sensor arranged at the second side of the display, an optical sensor arranged at the second side of the display, wherein the optical sensor comprises a plurality of photodetectors , and a calculation unit , wherein the ambient light sensor is configured to obtain sensor data comprising the irradiance of electromagnetic radiation reaching the ambient light sensor, the optical sensor is configured to determine the angle of incidence of at least a part of electromagnetic radiation reaching the optical sensor, the calculation unit is configured to correct the sensor data based on the angle of incidence determined by the optical sensor to obtain a corrected irradiance , and the calculation unit comprises a memory in which the transmission coef ficient of the display is stored for di f ferent angles of incidence .

[0026] The irradiance detected by the ambient light sensor can thus be corrected by employing the transmission coef ficients stored in the memory . This means , it is possible to determine the irradiance in front of the display and not only behind the display where the ambient light sensor is arranged . In most cases it is desired to determine the irradiance in front of the display since this is where potential users are present . The display device described herein enables to determine the irradiance in front of the display . Thus , the accuracy of determining the irradiance is improved . - 9 -

[0027] The display additionally enables to remove the influence of the angle of incidence from the irradiance measurement . In this way, the irradiance can be determined correctly even i f the display device is tilted . Therefore , the accuracy of the measurement is improved . An accurate measurement of the irradiance even i f the device is tilted is for example important for mobile devices or wearables .

[0028] According to at least one embodiment of the display device , correcting the sensor data comprises removing the influence of the display on the measurement of the ambient light sensor . The transmission coef ficients of the display are stored in the memory . With these , it can be determined for each angle of incidence determined by the optical sensor, what the irradiance measured by the ambient light sensor would be , i f the display had a transmission coef ficient of 1 . In this way, the corrected irradiance can be determined . For an assumed transmission coef ficient of 1 , no radiation is blocked or attenuated by the display . In this way, the influence of the display on the measurement is removed . This improves the accuracy of the measurement .

[0029] According to at least one embodiment of the display device , correcting the sensor data comprises removing the influence of the angle of incidence determined by the optical sensor on the measurement of the ambient light sensor . The angle of incidence is determined by the optical sensor . Since the irradiance changes along a cosine curve , the change in irradiance due to an angle of incidence that is di f ferent from 0 ° can be determined . Removing the influence of the angle of incidence can then mean that the value of the irradiance is determined that would be measured, i f the angle of incidence was 0 ° . This can be achieved by multiplying the - 10 - measured irradiance with the cosine compensation factor which equals 1 / cos ( angle of incidence ) . Removing the influence of the angle of incidence from the measurement improves the accuracy of the measurement .

[0030] According to at least one embodiment of the display device , the display comprises organic light-emitting diodes and / or micro light-emitting diodes . The organic light-emitting diodes and / or micro light-emitting diodes can comprise an organic or inorganic material , respectively . Seen in top view, the organic light-emitting diodes and / or micro lightemitting diodes may have polygonal or round shapes , like square , circular, or regular hexagonal . For example , a diameter or diagonal length of the organic light-emitting diodes and / or micro light-emitting diodes is less than or equal to 70 pm or less than or equal to 50 pm or less than or equal to 30 pm .

[0031] According to at least one embodiment of the display device , the optical sensor is configured to determine the angle of incidence of electromagnetic radiation emitted by a dominant radiation source . In other words , the optical sensor can be configured to determine the angle of incidence of electromagnetic radiation emitted by a dominant radiation source and reaching the optical sensor . In this way, a correction of sensor data obtained by the ambient light sensor is possible .

[0032] According to at least one embodiment of the display device , the optical sensor is configured to determine i f the electromagnetic radiation reaching the optical sensor comprises electromagnetic radiation from a dominant radiation source . I f electromagnetic radiation from a dominant 11 radiation source reaches the optical sensor, some photodetectors detect radiation from this radiation source and others do not . I f the electromagnetic radiation reaching the optical sensor does not comprise electromagnetic radiation from a dominant radiation source , all photodetectors detect similar intensity values . Thus , for determining i f electromagnetic radiation reaching the optical sensor comprises electromagnetic radiation from a dominant radiation source , the intensity detected by at least two photodetectors arranged at di f ferent positions within the optical sensor can be compared . I f the di f ferences between the intensities detected by di f ferent photodetectors are below a threshold value , it is assumed that no electromagnetic radiation from a dominant radiation source reaches the optical sensor . I f the di f ferences between the intensities detected by di f ferent photodetectors are above the threshold value , it is assumed that electromagnetic radiation from a dominant radiation source reaches the optical sensor .

[0033] According to at least one embodiment of the display device , a sensor aperture is arranged between the display and the optical sensor . The sensor aperture can be an aperture of the sensor cavity . The sensor aperture can have a main plane of extension that extends parallel to the main plane of extension of the display . The sensor aperture can be the only opening of the sensor cavity . Arranging the sensor aperture between the display and the optical sensor has the advantage that an image of incoming electromagnetic radiation is proj ected onto the optical sensor . This enables to determine the angle of incidence of at least a part of the electromagnetic radiation reaching the optical sensor . 12

[0034] According to at least one embodiment of the display device , the extent of the sensor aperture in a lateral direction is smaller than the extent in the lateral direction of the optical sensor, wherein the lateral direction extends parallel to a main plane of extension of the display . In this way, photodetectors of the optical sensor can detect incoming electromagnetic radiation also in the case that the display device is tilted with respect to a dominant radiation source .

[0035] According to at least one embodiment of the display device , the optical sensor is arranged spaced apart from the sensor aperture . The sensor aperture can be arranged above the optical sensor in a vertical direction, wherein the vertical direction extends perpendicular to the main plane of extension of the display . Arranging the sensor aperture spaced apart from the optical sensor has the advantage that an image of incoming electromagnetic radiation is proj ected onto the optical sensor . This enables to determine the angle of incidence of at least a part of the electromagnetic radiation reaching the optical sensor .

[0036] According to at least one embodiment of the display device , the photodetectors of the optical sensor have the same spectral sensitivity . This enables to use the photodetectors for determining the angle of incidence of at least a part of electromagnetic radiation reaching the optical sensor . The di f ferences in irradiance detected by the photodetectors are thus not due to di f ferent spectral sensitivities . Instead, di f ferences in irradiance detected by photodetectors arise , i f electromagnetic radiation from a dominant radiation source reaches the optical sensor . - 13 -

[0037] According to at least one embodiment of the display device , the display comprises opaque structures . This can mean, that the display is not transparent in all areas of the display but only in some areas . No electromagnetic radiation or nearly no electromagnetic radiation can pass the opaque structures . Thus , apertures are present in the display through which electromagnetic radiation can pass to the ambient light sensor and the optical sensor . The sensor aperture can have a larger extent in the lateral direction than the distance between two opaque structures of the display . The sensor aperture can have a larger extent in the lateral direction than any two structures of the display . The sensing aperture can have a larger extent in the lateral direction than the distance between two opaque structures of the display . The sensing aperture can have a larger extent in the lateral direction than any two structures of the display . This enables that a suf ficient amount of electromagnetic radiation reaches the optical sensor and the ambient light sensor .

[0038] According to at least one embodiment of the display device , the opaque structures extend completely through the display from the first side to the second side . The display can thus also comprise apertures that extend completely through the display from the first side to the second side . Due to the opaque structures , the overall transmission of the display is low which is why a correction is required .

[0039] According to at least one embodiment of the display device , a di f fuser is arranged between the optical sensor and the display . The di f fuser can have a scattering capability of 20 % at most or 10 % at most . In this way, electromagnetic radiation reaching the di f fuser is only slightly scattered so 14 that it is still possible to determine the angle of incidence of electromagnetic radiation from a dominant radiation source .

[0040] According to at least one embodiment of the display device , a Lambertian di f fuser is arranged between the ambient light sensor and the display . In this way, electromagnetic radiation reaching the ambient light sensor is homogenously distributed . This enables to determine the spectral composition of incoming radiation irrespective of the angle of incidence . The di f fuser above the optical sensor can have a lower scattering capability than the Lambertian di f fuser .

[0041] According to at least one embodiment of the display device , the optical sensor is arranged in a sensor cavity of the display device that is free of the ambient light sensor . This can mean, that the ambient light sensor and the optical sensor each have their own cavity, respectively . This enables that di f ferent di f fusers are employed for the two sensors or that no di f fuser is arranged above the optical sensor whereas a Lambertian di f fuser is arranged above the ambient light sensor .

[0042] According to at least one embodiment of the display device , the optical axes of the optical sensor, the ambient light sensor and the display extend parallel to each other . The optical axis of a component can extend perpendicular to the main plane of extension of that component .

[0043] According to at least one embodiment of the display device , the first side of the display faces an outside of the display device . The first side can thus be a front side . 15

[0044] Furthermore , a method for operating a display device is provided . The display device can preferably be employed for the method described herein . This means all features disclosed for the display device are also disclosed for the method for operating a display device and vice-versa .

[0045] According to at least one embodiment of the method for operating a display device , the method comprises obtaining sensor data by an ambient light sensor of the display device , the sensor data comprising the irradiance of electromagnetic radiation reaching the ambient light sensor .

[0046] According to at least one embodiment of the method for operating a display device , the method comprises determining the angle of incidence of at least a part of electromagnetic radiation reaching an optical sensor of the display device by the optical sensor .

[0047] According to at least one embodiment of the method for operating a display device , the method comprises correcting the sensor data based on the angle of incidence determined by the optical sensor to obtain a corrected irradiance by a calculation unit of the display device .

[0048] According to at least one embodiment of the method for operating a display device , the display device comprises a display with a first side and a second side , the first side facing away from the second side .

[0049] According to at least one embodiment of the method for operating a display device , the ambient light sensor and the optical sensor are arranged at the second side of the display . - 16 -

[0050] According to at least one embodiment of the method for operating a display device , the optical sensor comprises a plurality of photodetectors .

[0051] According to at least one embodiment of the method for operating a display device , in a calibration phase the transmission coef ficient of the display is detected for di f ferent angles of incidence . The transmission coef ficient of the display can be determined for a plurality of di f ferent angles of incidence during the calibration phase .

[0052] According to at least one embodiment of the method for operating a display device , the method comprises obtaining sensor data by an ambient light sensor of the display device , the sensor data comprising the irradiance of electromagnetic radiation reaching the ambient light sensor, determining the angle of incidence of at least a part of electromagnetic radiation reaching an optical sensor of the display device by the optical sensor, and correcting the sensor data based on the angle of incidence determined by the optical sensor to obtain a corrected irradiance by a calculation unit of the display device , wherein the display device comprises a display with a first side and a second side , the first side facing away from the second side , the ambient light sensor and the optical sensor are arranged at the second side of the display, the optical sensor comprises a plurality of photodetectors , and in a calibration phase the transmission coef ficient of the display is detected for di f ferent angles of incidence .

[0053] In the same way as the display device , the method for operating a display device enables to improve the accuracy of the measurement of the display device . 17

[0054] According to at least one embodiment of the method for operating a display device , the irradiance detected by at least two photodetectors of the optical sensor are compared with each other . It is also possible that the irradiance detected by a plurality of photodetectors of the optical sensor is compared with each other . With this comparison it is determined i f electromagnetic radiation from a dominant radiation source reaches the optical sensor . Furthermore , the angle of incidence of electromagnetic radiation from a dominant radiation source can be determined .

[0055] The following description of figures may further illustrate and explain exemplary embodiments . Components that are functionally identical or have an identical ef fect are denoted by identical references . Identical or ef fectively identical components might be described only with respect to the figures where they occur first . Their description is not necessarily repeated in successive figures .

[0056] Figure 1 shows an exemplary embodiment of the display device .

[0057] In figure 2 another exemplary embodiment of the display device is shown .

[0058] Figure 3 shows the angular dependency of detected electromagnetic radiation .

[0059] With figure 4 an exemplary embodiment of the method for operating a display device is described .

[0060] Figures 5 and 6 show exemplary embodiments of the optical sensor . - 18 -

[0061] Figure 1 shows an exemplary embodiment of the display device 20 . The display device 20 comprises a display 21 with a first side 22 and a second side 23 , the first side 22 facing away from the second side 23 . The first side 22 of the display 21 faces an outside of the display device 20 . The display 21 can comprise organic light-emitting diodes and / or micro lightemitting diodes .

[0062] Behind the display 21 , an ambient light sensor 24 is arranged . Thus , the ambient light sensor 24 is arranged at the second side 23 of the display 21 . The ambient light sensor 24 is configured to obtain sensor data comprising the irradiance of electromagnetic radiation reaching the ambient light sensor 24 . The ambient light sensor 24 is arranged in a sensing cavity 33 . Between the display 21 and the ambient light sensor 24 a sensing aperture 29 is arranged . The sensing aperture 29 is an aperture of the sensing cavity 33 . The ambient light sensor 24 comprises several photodiodes 37 arranged within a carrier component 36 of the display device 20 . As an example , five photodiodes 37 are shown in figure 1 . On at least some of the photodiodes 37 an optical filter 38 is arranged . The optical filters 38 can have di f ferent pass ranges . Some of the photodiodes 37 arranged at the edge of the ambient light sensor 24 are free of an optical filter 38 . A Lambertian di f fuser 31 is arranged between the ambient light sensor 24 and the display 21 . Between the Lambertian di f fuser 31 and the ambient light sensor 24 a material with a high transmittivity as for example glass is arranged .

[0063] The display device 20 further comprises an optical sensor 25 arranged at the second side 23 of the display 21 , wherein the optical sensor 25 comprises a plurality of photodetectors 26 .

[0064] As an example , three photodetectors 26 are shown in figure 1 . 19

[0065] The photodetectors 26 have the same spectral sensitivity . The optical sensor 25 is configured to determine the angle of incidence of at least a part of electromagnetic radiation reaching the optical sensor 25 . The optical sensor 25 can be configured to determine the angle of incidence of electromagnetic radiation emitted by a dominant radiation source . Moreover, the optical sensor 25 can be configured to determine i f the electromagnetic radiation reaching the optical sensor 25 comprises electromagnetic radiation from a dominant radiation source .

[0066] Between the display 21 and the optical sensor 25 , a sensor aperture 28 is arranged . The extent of the sensor aperture 28 in a lateral direction x is smaller than the extent in the lateral direction x of the optical sensor 25 , wherein the lateral direction x extends parallel to a main plane of extension of the display 21 . The optical sensor 25 is arranged spaced apart from the sensor aperture 28 . Between the sensor aperture 28 and the optical sensor 25 a material with a high transmittivity as for example glass is arranged . The optical sensor 25 is arranged in a sensor cavity 32 of the display device 20 that is free of the ambient light sensor 24 . The arrows indicate that electromagnetic radiation reaching the optical sensor 25 passes the display 21 and the sensor aperture 28 .

[0067] The optical axes of the optical sensor 25 , the ambient light sensor 24 and the display 21 extend parallel to each other .

[0068] Furthermore , the display 21 comprises a calculation unit 27 that is configured to correct the sensor data based on the angle of incidence determined by the optical sensor 25 to obtain a corrected irradiance . The calculation unit 27 20 comprises a memory 40 in which the transmission coef ficient of the display 21 is stored for di f ferent angles of incidence . Correcting the sensor data can comprise removing the influence of the display 21 on the measurement of the ambient light sensor 24 and / or correcting the sensor data can comprise removing the influence of the angle of incidence determined by the optical sensor 25 on the measurement of the ambient light sensor 24 .

[0069] In figure 2 another exemplary embodiment of the display device 20 is shown . The display 21 comprises opaque structures 39 which extend completely through the display 21 from the first side 22 to the second side 23 . It is shown with arrows that electromagnetic radiation can only pass the display 21 through the apertures between the opaque structures 39 . Electromagnetic radiation reaching the Lambertian di f fuser 31 is scattered at the Lambertian di f fuser 31 . Between the optical sensor 25 and the display 21 an optional di f fuser 30 with a low scattering capability is arranged .

[0070] Figure 3 shows the angular dependency of detected electromagnetic radiation . On the x-axis the angle of incidence of electromagnetic radiation reaching the display 21 is plotted . On the y-axis the ef ficiency of detecting the irradiance is plotted as a solid line . This curve has the shape of a cosine function . This means , for an angle of incidence of 0 ° , the irradiance is correctly detected . Once the angle of incidence is di f ferent from 0 ° , the detected irradiance is decreased . This curve refers to an ideal situation . Furthermore , on the y-axis the ef ficiency of detecting the irradiance behind the display 21 is plotted as a dashed line . This means , also the display 21 has an impact - 21 - on the detected irradiance . Once the transmission coef ficient of the display 21 is known for di f ferent angles of incidence it is possible to correct sensor data for the di f ference between the two curves . This means , the sensor data can be corrected to be free of an influence of the display 21 on the measurement .

[0071] With figure 4 an exemplary embodiment of the method for operating a display device 20 is described . In a first step S I of the method the transmission coef ficient of the display 21 is detected for di f ferent angles of incidence in a calibration phase . In a second step S2 of the method sensor data is obtained by an ambient light sensor 24 of the display device 20 , the sensor data comprising the irradiance of electromagnetic radiation reaching the ambient light sensor 24 . In a third step S3 of the method the angle of incidence of at least a part of electromagnetic radiation reaching an optical sensor 25 of the display device 20 is determined by the optical sensor 25 . For this purpose , the irradiance detected by at least two photodetectors 26 of the optical sensor 25 can be compared with each other . In a fourth step S4 of the method the sensor data is corrected based on the angle of incidence determined by the optical sensor 25 to obtain a corrected irradiance by a calculation unit 27 of the display device 20 .

[0072] Figure 5 shows a top view on an exemplary embodiment of the optical sensor 25 . The optical sensor 25 comprises a central photodetector 34 that is arranged in the center of the optical sensor 25 . The optical sensor 25 also comprises a plurality of outer photodetectors 35 that are arranged at the edges of the optical sensor 25 . The outer photodetectors 35 are arranged along the edges of a square . The sensor aperture - 22 -

[0073] 28 is depicted in the same plane with the photodetectors 34 , 35 and has a lateral extent that is smaller than the lateral extent of the optical sensor 25 . In the top view, the outer photodetectors 35 are covered by opaque material surrounding the sensor aperture 28 . Thus , only the central photodetector 34 is arranged below the sensor aperture 28 . The sensor aperture 28 has the shape of a square .

[0074] In this embodiment , the central photodetector 34 may be used for reference , in order to properly and comparably identi fy variations in detected irradiance by the other photodetectors 26 by comparison . Further, such central photodetector 34 will also facilitate identi fication of a point type source of radiation, and therefore signi ficantly improve evaluation capacity of the display device 20 .

[0075] The outer photodetectors 35 can be arranged pairwise in opposite positions relative to the central photodetector 34 , such that relative di f ferences in irradiation in the direction defined by such pairs of outer photodetectors 35 may be detected and evaluated easily .

[0076] Figure 6 shows a top view on an exemplary embodiment of the optical sensor 25 . The only di f ferences in comparison to the embodiment shown in figure 5 are that the outer photodetectors 35 are arranged along the edge of a circle around the central photodetector 34 . The sensor aperture 28 has the shape of a circle .

[0077] It will be appreciated that the disclosure is not limited to the disclosed embodiments and to what has been particularly shown and described hereinabove . Rather, features recited in separate dependent claims or in the description may - 23 - advantageously be combined. Furthermore, the scope of the disclosure includes those variations and modifications, which will be apparent to those skilled in the art. The term "comprising", insofar it was used in the claims or in the description, does not exclude other elements or steps of a corresponding feature or procedure. In case that the terms "a" or "an" were used in conjunction with features, they do not exclude a plurality of such features. Moreover, any reference signs in the claims should not be construed as limiting the scope.

[0078] This patent application claims priority from German patent application 10 2024 123 143.2, the disclosure content of which is hereby included by reference.

[0079] - 24 -

[0080] References

[0081] 20 display device

[0082] 21 display

[0083] 22 first side

[0084] 23 second side

[0085] 24 ambient light sensor

[0086] 25 optical sensor

[0087] 26 photodetector

[0088] 27 calculation unit

[0089] 28 sensor aperture

[0090] 29 sensing aperture

[0091] 30 di f fuser

[0092] 31 Lambertian di f fuser

[0093] 32 sensor cavity

[0094] 33 sensing cavity

[0095] 34 central photodetector

[0096] 35 outer photodetector

[0097] 36 carrier component

[0098] 37 photodiode

[0099] 38 optical filter

[0100] 39 opaque structure

[0101] 40 memory

[0102] S 1-S4 steps x lateral direction

Claims

- 25 -Claims1. Display device (20) comprising:- a display (21) with a first side (22) and a second side (23) , the first side (22) facing away from the second side (23) ,- an ambient light sensor (24) arranged at the second side (23) of the display (21) ,- an optical sensor (25) arranged at the second side (23) of the display (21) , wherein the optical sensor (25) comprises a plurality of photodetectors (26) , and- a calculation unit (27) , wherein- the ambient light sensor (24) is configured to obtain sensor data comprising the irradiance of electromagnetic radiation reaching the ambient light sensor (24) ,- the optical sensor (25) is configured to determine the angle of incidence of at least a part of electromagnetic radiation reaching the optical sensor (25) ,- the calculation unit (27) is configured to correct the sensor data based on the angle of incidence determined by the optical sensor (25) to obtain a corrected irradiance, and- the calculation unit (27) comprises a memory (40) in which the transmission coefficient of the display (21) is stored for different angles of incidence.

2. Display device (20) according to the preceding claim, wherein correcting the sensor data comprises removing the influence of the display (21) on the measurement of the ambient light sensor (24) .

3. Display device (20) according to one of the preceding claims, wherein correcting the sensor data comprises removing the influence of the angle of incidence determined by the26 optical sensor (25) on the measurement of the ambient light sensor (24 ) .

4. Display device (20) according to one of the preceding claims, wherein the display (21) comprises organic lightemitting diodes and / or micro light-emitting diodes.

5. Display device (20) according to one of the preceding claims, wherein the optical sensor (25) is configured to determine the angle of incidence of electromagnetic radiation emitted by a dominant radiation source.

6. Display device (20) according to one of the preceding claims, wherein the optical sensor (25) is configured to determine if the electromagnetic radiation reaching the optical sensor (25) comprises electromagnetic radiation from a dominant radiation source.

7. Display device (20) according to one of the preceding claims, wherein a sensor aperture (28) is arranged between the display (21) and the optical sensor (25) .

8. Display device (20) according to the preceding claim, wherein the extent of the sensor aperture (28) in a lateral direction (x) is smaller than the extent in the lateral direction (x) of the optical sensor (25) , wherein the lateral direction (x) extends parallel to a main plane of extension of the display (21) .

9. Display device (20) according to one of claims 7 or 8, wherein the optical sensor (25) is arranged spaced apart from the sensor aperture (28) .- 27 -10. Display device (20) according to one of the preceding claims, wherein the photodetectors (26) of the optical sensor (25) have the same spectral sensitivity.

11. Display device (20) according to one of the preceding claims, wherein the display (21) comprises opaque structures (39) .

12. Display device (20) according to the preceding claim, wherein the opaque structures (39) extend completely through the display (21) from the first side (22) to the second side (23) .

13. Display device (20) according to one of the preceding claims, wherein a diffuser (30) is arranged between the optical sensor (25) and the display (21) .

14. Display device (20) according to one of the preceding claims, wherein a Lambertian diffuser (31) is arranged between the ambient light sensor (24) and the display (21) .

15. Display device (20) according to one of the preceding claims, wherein the optical sensor (25) is arranged in a sensor cavity (32) of the display device (20) that is free of the ambient light sensor (24) .

16. Display device (20) according to one of the preceding claims, wherein the optical axes of the optical sensor (25) , the ambient light sensor (24) and the display (21) extend parallel to each other.- 28 -17. Display device (20) according to one of the preceding claims, wherein the first side (22) of the display (21) faces an outside of the display device (20) .

18. Method for operating a display device (20) , the method comprising :- obtaining sensor data by an ambient light sensor (24) of the display device (20) , the sensor data comprising the irradiance of electromagnetic radiation reaching the ambient light sensor (24) ,- determining the angle of incidence of at least a part of electromagnetic radiation reaching an optical sensor (25) of the display device (20) by the optical sensor (25) , and- correcting the sensor data based on the angle of incidence determined by the optical sensor (25) to obtain a corrected irradiance by a calculation unit (27) of the display device (20) , wherein- the display device (20) comprises a display (21) with a first side (22) and a second side (23) , the first side (22) facing away from the second side (23) ,- the ambient light sensor (24) and the optical sensor (25) are arranged at the second side (23) of the display (21) ,- the optical sensor (25) comprises a plurality of photodetectors (26) , and- in a calibration phase the transmission coefficient of the display (21) is detected for different angles of incidence.

19. Method for operating a display device (20) according to the preceding claim, wherein the irradiance detected by at least two photodetectors (26) of the optical sensor (25) is compared with each other.

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