Optical sensor with five spectrally equidistant detection channels for combined colour sensing and ambient light spectral reconstruction

Abstract

An optical sensor (1) with a plurality of detection channels is specified, wherein - the detection channels (2) each comprise a photosensitive area (15) and a filter (17) to define a spectral sensitivity of the respective detection channel (2); - the detection channels (2) comprise a first set of detection channels with three detection channels (21X, 21Y, 21Z) configured to approximate the three CIE1931 color matching functions (I), (II), and ̅(III) (3X, 3Y, 3Z); - the plurality of detection channels (2) comprises a first additional detection channel (22A) with a wavelength of maximum sensitivity between the maxima of the color matching functions (III) and (II); - the plurality of detection channels comprises a second additional detection channel (22B) with a wavelength of maximum sensitivity larger than the maximum of the color matching function ̅(I); - the three detection channels of the first set of detection channels (21X, 21Y, 21Z), the first additional detection channel (22A), and the second additional detection channel (22B) taken together are arranged in a spectrally equidistant manner with a tolerance of at most 20 nm. Further, an electronic device (10) is specified.

Description

[0001] 2025PF00276 March 12, 2026

[0002] P2025, 0183 WO N - 1 -

[0003] Description

[0004] OPTICAL SENSOR WITH FIVE SPECTRALLY EQUIDISTANT DETECTION CHANNELS FOR COMBINED COLOUR SENSING AND AMBIENT LIGHT SPECTRAL RECONSTRUCTION

[0005] The present application relates to an optical sensor and to an electronic device with an optical sensor.

[0006] Optical sensors configured for color sensing typically use three detection channels matched to the sensitivity of the human eye. Optical sensors for spectral reconstruction, on the other hand, require spectrally independent detection channels that cover the relevant spectral range without any energetic dips. Otherwise, the reconstruction may lose spectrally narrow energetic power information.

[0007] It is an obj ect to provide an optical sensor that enables color measurements and spectral reconstruction in an efficient manner.

[0008] This obj ect is achieved, inter alia, by an optical sensor and an electronic device according to the independent claims.

[0009] Further configurations and developments are the subj ect of the dependent claims.

[0010] An optical sensor comprising a plurality of detection channels is specified.

[0011] According to at least one embodiment of the optical sensor, each detection channel comprises a photosensitive area and a filter to define a spectral sensitivity of the respective detection channel. For example, the photosensitive area is provided by a photodiode based on a semiconductor material such as silicon. In particular, all photosensitive areas of2025PF00276 March 12, 2026

[0012] P2025, 0183 WO N 2

[0013] the detection channels may be based on the same semiconductor material.

[0014] The photosensitive areas of the detection channels may be integrated in a common sensor chip. Alternatively, the photosensitive areas may be provided by separate devices.

[0015] For example, the filter is configured as a bandpass filter.

[0016] For example, the filter comprises an interference filter, an absorption filter, a plasmonic filter or a combination thereof.

[0017] An interference filter may be formed by a dielectric layer stack wherein each layer of the stack may be adapted with respect to its layer thickness and its refractive index such that optical interference effects at the interfaces between the layers result in the intended transmission spectrum.

[0018] In an absorption filter electromagnetic radiation with wavelengths outside the intended transmission spectrum of the filter can be absorbed. A plasmonic filter may be formed by structured metal layers that exhibit plasmonic properties.

[0019] According to at least one embodiment of the optical sensor, the detection channels comprise a first set of detection channels. In particular, the detection channels of the first set of detection channels comprise three detection channels configured to approximate the three CIE 1931 color matching functions x̄(λ), ȳ(λ) and z̄(λ).

[0020] The color matching function x̄(λ) comprises two maxima in the visible spectral range. Its global maximum is located in the2025PF00276 March 12, 2026

[0021] P2025, 0183 WO N 3

[0022] red spectral range near 600 nm and a further local maximum is located in the blue spectral range near 450 nm. The ȳ(λ) color matching function comprises a maximum in the green spectral range near 550 nm. The z̄(λ) color matching function comprises one peak in the blue spectral range near 450 nm. Collectively, these three color matching functions describe the CIE standard observer.

[0023] These color matching functions represent the ideal spectral sensitivity curves of three linear light detectors providing the tristimulus values X, Y and Z in the CIE XYZ color space, wherein Y is the luminance. Three tristimulus values can be determined for each color sensed by a human observer.

[0024] Thus, the tristimulus values X, Y and Z can be derived from the signals of the detection channels of the first set of detection channels.

[0025] For example, the first set of detection channels comprises a first detection channel with a wavelength of maximum sensitivity that differs from the maximum of the color matching function x̄(λ) by at most 20 nm or at most 10 nm.

[0026] A full width at half maximum of the spectral sensitivity of the first detection channel may differ from the full width at half maximum of the color matching function x̄(λ) by at most 30 nm or at most 20 nm.

[0027] For example, the first set of detection channels comprises a second detection channel with a wavelength of maximum sensitivity that differs from the maximum of the color matching function ȳ(λ) by at most 20 nm or at most 10 nm.A full width at half maximum of the spectral sensitivity of the second detection channel may differ from the full width at half maximum of the color matching function ȳ(λ) by at most 30 nm or at most 20 nm.

[0028] For example, the first set of detection channels comprises a third detection channel with a wavelength of maximum sensitivity that differs from the maximum of the color matching function z̄(λ) by at most 20 nm or at most 10 nm. A full width at half maximum of the spectral sensitivity of the third detection channel may differ from the full width at half maximum of the color matching function z̄(λ) by at most 30 nm or at most 20 nm.

[0029] According to a further embodiment of the optical sensor, the plurality of detection channels comprises a first additional detection channel with a wavelength of maximum sensitivity between the maxima of the color matching functions z̄(λ) and ȳ(λ). For example, the wavelength of maximum sensitivity of the first additional detection channel is spectrally spaced apart from the maxima of the color matching functions z̄(λ) and ȳ(λ) by at least 20 nm or at least 30 nm.

[0030] Further, the first additional detection channel may be the only detection channel in addition to the second detection channel of the first set of detection channels of the optical sensor that has a wavelength of maximum sensitivity between the maxima of the color matching functions z̄(λ) and x̄(λ).

[0031] In particular, the wavelength of maximum sensitivity of the first additional detection channel is located between the wavelength of maximum sensitivity of the second detection2025PF00276 March 12, 2026

[0032] P2025, 0183 WO N 5

[0033] channel and the wavelength of maximum sensitivity of the third detection channel. In particular, the first additional detection channel is the only detection channel of the optical sensor that has a wavelength of maximum sensitivity between the wavelengths of maximum sensitivity of the third detection channel and the second detection channel of the first set of detection channels.

[0034] According to at least one embodiment of the optical sensor, the plurality of detection channels comprises a second additional detection channel with a wavelength of maximum sensitivity larger than the maximum of the color matching function x̄(λ). For example, the wavelength of maximum sensitivity is by at least 20 nm or at least 30 and / or at most 80 nm larger than the global maximum of the color matching function x̄(λ). In particular, the second additional detection channel is configured to detect the low energy fraction of the radiation in the visible spectral range.

[0035] According to at least one embodiment of the optical sensor, the three detection channels of the first set of detection channels, the first additional detection channel and the second additional detection channel taken together are arranged in a spectrally equidistant manner with a tolerance of at most 20 nm or at most 10 nm.

[0036] Thus, the optical sensor provides five spectrally equidistant or at least substantially spectrally equidistant detection channels.

[0037] In particular, the entire visible spectral range or at least the relevant part thereof may be covered by the five spectrally equidistant detection channels. This helps to2025PF00276 March 12, 2026

[0038] P2025, 0183 WO N 6

[0039] obtain spectral information and / or on the brightness of the ambient light perceived by the human eye in addition to the color-related information provided by the first set of detection channels with a minimum number of detection channels.

[0040] In at least one embodiment of the optical sensor, the optical sensor comprises a plurality of detection channels wherein the detection channels each comprise a photosensitive area and a filter to define a spectral sensitivity of the respective detection channel. The detection channels comprise a first set of detection channels with three detection channels configured to approximate the three CIE 1931 color matching functions x̄(λ), ȳ(λ) and z̄(λ). The plurality of detection channels comprises a first additional detection channel with a wavelength of maximum sensitivity between the maxima of the color matching functions z̄(λ) and ȳ(λ). The plurality of detection channels comprises a second additional detection channel with a wavelength of maximum sensitivity larger than the maximum of the color matching function x̄(λ). The three detection channels of the first set of detection channels, the first additional detection channel and the second additional detection channel taken together are arranged in a spectrally equidistant manner with a tolerance of at most 20 nm.

[0041] During operation of the optical sensor, the signals from the first set of detection channels may be used for color sensing or the determination of color-related parameters such as illuminance or correlated color temperature (CCT). In particular, the tristimulus values X, Y, and Z can be obtained from the signals of the detection channels of the first set of detection channels.2025PF00276 March 12, 2026

[0042] P2025, 0183 WO N 7

[0043] The additional detection channels provide further functionality for spectral sensing applications.

[0044] In particular, the additional detection channels are spectrally arranged such that all five of the detection channels homogenously cover the entire spectral range and provide sufficient spectral independency for spectral reconstruction of the impinging light.

[0045] As five detection channels are sufficient to combine color and spectral sensing applications, the complexity of the optical sensor and the manufacturing costs can be minimized.

[0046] According to at least one embodiment of the optical sensor, an average distance between the three detection channels of the first set of detection channels, the first additional detection channel and the second additional detection channel taken together is in a range from 40 nm to 60 nm.

[0047] According to at least one embodiment of the optical sensor, the first additional detection channel has a sensitivity with a full width at half maximum in a range from 50 nm to 70 nm. Thus, the first additional detection channel efficiently covers the spectral gap between the second detection channel and the third detection channel of the first set of detection channels.

[0048] According to at least one embodiment of the optical sensor, the wavelength of maximum sensitivity of the first additional detection channel is in a range from 480 nm to 520 nm, in particular in a range from 490 nm to 500 nm. Thus, the wavelength of maximum sensitivity of the first additional detection channel substantially corresponds to the geometric2025PF00276 March 12, 2026

[0049] P2025, 0183 WO N 8

[0050] average of the wavelengths of the second detection channel and the third detection channel.

[0051] According to at least one embodiment of the optical sensor, the second additional detection channel has a sensitivity with a full width at half maximum in a range from 60 nm to 80 nm. Thus, the second additional detection channel efficiently covers the spectral range for a light in the visible spectral range having wavelengths larger than the wavelength of maximum sensitivity of the first detection channel.

[0052] According to at least one embodiment of the optical sensor, the wavelength of maximum sensitivity of the second additional detection channel is in a range from 630 nm to 680 nm, in particular in a range from 640 nm to 670 nm.

[0053] According to at least one embodiment of the optical sensor, the optical sensor comprises exactly five detection channels with wavelengths of maximum sensitivity in a range from 400 nm to 700 nm. Thus, color and spectral sensing capabilities are achieved with a minimum number of detection channels.

[0054] However, the optical sensor may comprise one or more further detection channels with wavelengths of maximum sensitivity located outside the spectral range from 400 nm to 700 nm, for example in the infrared spectral range.

[0055] According to at least one embodiment of the optical sensor, the optical sensor is configured to approximate the color matching function x̄(λ) by means of a linear combination of the sensitivities of two detection channels of the first set of detection channels. In particular, the spectral contribution around the local maximum having a shorter wavelength than the2025PF00276 March 12, 2026

[0056] P2025, 0183 WO N 9

[0057] global maximum of spectral sensitivity may be approximated using the third detection channel of the first set of detection channels. This increases the spectral independence of the first detection channel and the third detection channel of the first set of detection channels.

[0058] Alternatively, the first detection channel may be configured such that its spectral sensitivity approximates the color matching function x̄(λ). In this case, each of the detection channels of the first set of detection channels is configured to approximate exactly one of the three color matching functions.

[0059] According to at least one embodiment of the optical sensor, the wavelengths of maximum sensitivity of the first set of detection channels each differ from the maximum of the closest color matching function by at most 15 nm or at most 10 nm.

[0060] Thus, a reliable approximation of the color matching functions can be obtained by means of the associated detection channel of the first set of detection channels.

[0061] According to at least one embodiment of the optical sensor, the optical sensor is configured to provide a combined spectral sensitivity by means of a linear combination of the sensitivities of the three detection channels of the first set of detection channels, the first additional detection channel and the second additional channel, wherein the combined spectral sensitivity is constant at least in a range from 470 nm to 620 nm with a tolerance of at most 20% or at most 10%. Thus, the signals from the individual detection channels may be multiplied with associated individual scaling factors such that the sum of these scaled sensitivities provides a2025PF00276 March 12, 2026

[0062] P2025, 0183 WO N 10

[0063] substantially constant combined spectral sensitivity of the optical sensor. Thus, the obj ective luminance of the impinging light can be measured in this range without any significant spectral gaps.

[0064] According to at least one embodiment of the optical sensor, the optical sensor is configured to perform a spectral reconstruction of an ambient light. In particular, the optical sensor may be configured to perform a light source analysis of the ambient light. For example, the optical sensor may be configured to distinguish between natural light sources such as sunlight, fire, or candlelight or electric light sources such as lightbulbs, fluorescent lamps or light-emitting diode based light sources.

[0065] Further, an electronic device is specified. In particular, the electronic device comprises an optical sensor having one or more features of the optical sensor described above.

[0066] In particular, the electronic device may comprise a display. For example, the electronic device may be a mobile or handheld device such as a smartphone, a tablet or a notebook or a wearable device such as a smartwatch or a stationary device such as a computer monitor or a TV set.

[0067] According to a further embodiment of the electronic device, the optical sensor is arranged behind the display in a top view onto the display. In this case, the ambient light has to pass through the display before it impinges onto the optical sensor. Thus, the transmittance of the display has an impact on the spectral distribution of the impinging light. This effect may be accounted for when performing a color and / or a spectral analysis of the ambient light.2025PF00276 March 12, 2026

[0068] P2025, 0183 WO N - 11 -

[0069] For example, the display properties such as the white point may be adapted to increase the users' comfort based on a spectral reconstruction of the ambient light using the optical sensor.

[0070] Features described above in connection with at least one embodiment of the optical sensor or the electronic device can be combined with other features described in connection with at least one embodiment of the optical sensor or the electronic device unless they are contradictory.

[0071] Further features and expediencies will become apparent from the subsequent description of the exemplary embodiments in connection with the Figures.

[0072] In the exemplary embodiments and Figures similar or similarly acting constituent parts are labeled with the same reference signs. Only the differences with respect to the individual exemplary embodiments are described. Unless specified otherwise, the description of a part or feature in one exemplary embodiment applies to a corresponding part or feature in another exemplary embodiment as well.

[0073] In the Figures:

[0074] Figure 1A shows an exemplary embodiment of an optical sensor in a cross-sectional view;

[0075] Figure 1B shows spectral sensitivities S(A / W) of detection channels according to an exemplary embodiment of an optical sensor;2025PF00276 March 12, 2026

[0076] P2025, 0183 WO N - 12 -

[0077] Figure 1C shows an example of combined spectral sensitivities S (A / W) of detection channels according to an exemplary embodiment of an optical sensor;

[0078] Figure 1D shows a reference example of combined spectral sensitivities S(A / W) of three detection channels for color sensing;

[0079] Figure 1E shows an exemplary embodiment of an electronic device with an optical sensor in a cross-sectional view;

[0080] Figure 2A shows spectral sensitivities S(A / W) of detection channels according to exemplary embodiments of optical sensors with process-related variations;

[0081] Figure 2B shows signals S of detection channels fitted to the three CIE1931 color matching functions according to exemplary embodiments of optical sensors with process-related variations;

[0082] Figures 3A, 3B, 3C, 3D, 3E, 3F, 3G, 3H, 3I each show an example of a spectrum of an ambient light, a nominal spectral reconstruction for an exemplary embodiment of an optical sensor, and spectral reconstructions for associated optical sensors with process-related variations;

[0083] Figure 4A shows spectral sensitivities S(A / W) of detection channels according to exemplary embodiments of optical sensors located underneath a display with process-related variations as shown in Figure 2A;

[0084] Figure 4B shows signals S of detection channels fitted to the three CIE1931 color matching functions according to exemplary2025PF00276 March 12, 2026

[0085] P2025, 0183 WO N 13

[0086] embodiments of optical sensors located underneath a display with process-related variations;

[0087] Figure 4C schematically shows a transmittance T of a display as a function of the wavelength; and

[0088] Figures 5A, 5B, 5C, 5D, 5E, 5F, 5G, 5H, 5I each show an example of a spectrum of an ambient light, a nominal spectral reconstruction for an exemplary embodiment of an optical sensor underneath a display, and spectral reconstructions for associated optical sensors with process-related variations.

[0089] The elements illustrated in the figures and their size relationships among one another are not necessarily true to scale. Rather, individual elements or layer thicknesses may be represented with an exaggerated size for the sake of better representability and / or for the sake of better understanding.

[0090] An exemplary embodiment of an optical sensor 1 is illustrated in Figure 1A. An electronic device 10 with an optical sensor 1 is shown in Figure IE.

[0091] The optical sensor 1 comprises a plurality of detection channels 2.

[0092] The detection channels 2 each comprise a photosensitive area 15 and a filter 17. By means of the filter 17, the spectral sensitivity of the respective detection channel 2 can be defined. Each filter 17 may comprise or consist of an interference filter, an absorption filter, a plasmonic filter or a combination thereof.2025PF00276 March 12, 2026

[0093] P2025, 0183 WO N 14

[0094] As illustrated in Figure 1A, the optical sensor 1 may comprise a sensor chip 11 with the photosensitive areas 15. The sensor chip 11 is arranged on a substrate 14 and electrically connected to the substrate via bonding wires 16. The optical sensor 1 may further comprise a sensor package 12 providing an aperture 13, allowing the light to be detected to reach the photosensitive areas 15.

[0095] The photosensitive areas 15 may be formed in a common semiconductor chip or be provided as separate elements such as individual photodiodes connected to the substrate 14.

[0096] As illustrated in Figure IB, the optical sensor 1 comprises a first set of detection channels with a first detection channel 21X, a second detection channel 21Y and a third detection channel 21Z configured to approximate the three CIE 1931 color matching functions x̄(λ), ȳ(λ) and z̄(λ).

[0097] The three color matching functions 3X, 3Y and 3Z are illustrated in Figure ID in a normalized representation.

[0098] The plurality of detection channels 2 further comprises a first additional detection channel with a wavelength of maximum sensitivity between the wavelengths of maximum sensitivity of the second detection channel 21Y and the third detection channel 21Z approximating the color matching functions z̄(λ) and ȳ(λ) respectively.

[0099] The plurality of detection channels 2 further comprises a second additional detection channel 22B with a wavelength of maximum sensitivity larger than the wavelength of maximum sensitivity of the first detection channel 21X approximating the color matching function x̄(λ).2025PF00276 March 12, 2026

[0100] P2025, 0183 WO N - 15 -

[0101] The three detection channels of the first set of detection channels 21X, 21Y, 21Z, the first additional detection channel 22A and the second additional detection channel 22B taken together, are arranged in a spectrally equidistant manner with a tolerance of at most 20 nm or at most 10 nm. In the exemplary embodiment shown, the average distance between the detection channels 2 is about 50 nm. However, the average distance may vary in a range from 40 nm to 60 nm, for example. A spectrally equidistant arrangement of the detection channels 2 maximizes the independence of the signals provided by the individual detection channels 2. This facilitates spectral reconstruction operations.

[0102] The full widths at half maximum of the detection channels 2 are at least 50 nm. As illustrated in Figure 1C, this helps to obtain a combined spectral sensitivity 23 by means of a linear combination of the sensitivities of the three detection channels 21X, 21Y, 21Z of the first set of detection channels, the first additional detection channel 22A and the second additional detection channel 22B, wherein the combined spectral sensitivity is constant, at least in a range from 470 nm to 620 nm with a tolerance of at most 20% or at most 10% or at most 5%.

[0103] Thus, the combined spectral sensitivity 23 does not have any spectral dips where the combined spectral sensitivity 23 is significantly lower than the maximum combined spectral sensitivity within said spectral range.

[0104] For comparison, Figure ID shows a reference combined spectral sensitivity 23R if three detection channels were used that are matched to the normalized color matching functions 3X, 3Y, 3Z. In this case, the combined spectral sensitivity has a2025PF00276 March 12, 2026

[0105] P2025, 0183 WO N 16

[0106] prominent minimum at wavelengths around 500 nm compared to the maximum of the combined sensitivity located around 590 nm.

[0107] For example, the first additional detection channel 22A has a sensitivity with a full width at half maximum in a range from 50 nm to 70 nm. A wavelength of maximum sensitivity of the first additional detection channel is in a range from 480 nm to 520 nm, in particular in a range from 490 nm to 500 nm.

[0108] The second additional detection channel 22B may have a sensitivity with a full width at half maximum in a range from 60 nm to 80 nm. The wavelength of maximum sensitivity of the second additional detection channel 22B may be in a range from 630 nm to 680 nm, in particular in a range from 640 nm to 670 nm.

[0109] As shown in Figure IB, the optical sensor 1 may comprise exactly five detection channels 2 with wavelengths of maximum sensitivity in a range from 400 nm to 700 nm. The detection channels 21X, 21Y, 21Z of the first set of detection channels may be used for color sensing applications based on the obtained tristimulus values X, Y, and Z.

[0110] By means of the first additional detection channel 22A and the second additional detection channel 22B in addition to the first set of detection channels, spectral reconstruction operations can be performed in a reliable manner. This will be described in connection with the subsequent figures.

[0111] The full widths at half maximum may be at least 40 nm or at least 50 nm and / or at most 90 nm or at most 80 nm for all of the detection channels. It hast turned out that spectral sensitivity distributions having a comparably large full width2025PF00276 March 12, 2026

[0112] P2025, 0183 WO N 17

[0113] at half maximum allow to cover the spectral range with a minimum number of detection channels. On the other hand, a too large full width at half maximum results in a too strong spectral overlap between spectrally adjacent detection channels, thereby affecting the spectral independence of the detection channels.

[0114] The optical sensor 1 may comprise further detection channels 2 in addition to the five detection channels illustrated above, in particular further detection channels with maxima of spectral sensitivity located outside the visible spectral range. For example, a further detection channel may be sensitive in the infrared spectral range.

[0115] In the exemplary embodiment of the electronic device 10 illustrated in Figure IE, the optical sensor 1 is arranged behind a display 18 of the electronic device 10.

[0116] Thus, the ambient light 19 has to pass through the display 18 before it impinges onto the optical sensor 1.

[0117] However, the optical sensor 1 may also be arranged laterally beside the display 18 or be used in an electronic device without a display. For example, the electronic device 10 is a mobile electronic device such as a smartphone, a tablet or a notebook or a wearable device such as a smartwatch. However, the electronic device 10 may also be a stationary device such as a TV set or a computer monitor.

[0118] Figure 2A illustrates nominal spectral sensitivities of the detection channels as described in connection with Figure IB and associated spectral sensitivities in the case of process variations. For example, variations in the thicknesses of2025PF00276 March 12, 2026

[0119] P2025, 0183 WO N 18

[0120] layers of the filters 17 may result in a slight spectral shift.

[0121] In Figure 2B, these signals are used to approximate the color matching functions 3X, 3Y and 3Z. The color matching function 3X is approximated using a linear combination of the signals from the first detection channel 21X and the third detection channel 21Z. Thus, the signal around the local maximum in the short wavelength range is approximated using the third detection channel 21Z that is also used for an approximation of the color matching functions 3Z.

[0122] The signals 35 including the process-related variations illustrate that a reliable approximation of the color matching functions can be obtained, even if small process-related variations occur, for example due to variations of layer thicknesses of the filters 17. Thus, the performance of the optical sensor 1 is robust against process-related variations.

[0123] Figures 3A to 31 illustrate spectral reconstructions of spectra of ambient light impinging onto the optical sensor 1.

[0124] In the figures, curves 41 represent the spectrum of the ambient light. Curves 42 represent the nominal reconstructed spectrum. Curves 43 relate to reconstructed spectra considering process-related fluctuations.

[0125] In Figure 3A, the ambient light substantially corresponds to daylight. In Figure 3B, the ambient light is candlelight.

[0126] In Figure 3C, the ambient light has a substantially equal distribution within the visible spectral range.2025PF00276 March 12, 2026

[0127] P2025, 0183 WO N 19

[0128] Figures 3D, 3E and 3F relate to spectra of fluorescent lamps wherein the fluorescent lamp of Figure 3D produces warm white light, the fluorescent lamp of Figure 3E neutral white light and the fluorescence lamp of Figure 3F produces cold white light.

[0129] Figures 3G to 31 relate to spectra of LED-based light sources with luminescence conversion elements wherein the LED light source of Figure 3G is configured to produce warm white light, the LED light source of Figure 3H is configured to produce neutral white light and the LED light source of Figure 31 is configured to produce cold white light.

[0130] The spectral reconstruction may be performed using the signals from all of the detection channels. Generally, a spectral reconstruction may be performed using an m x n matrix wherein m is the number of detection channels 2 used and n is the number of spectral components to be considered. For example, m=5 and n=3 may apply.

[0131] As for Figures 3A to 3C, the spectra of the ambient light can be fitted with a high accuracy in the relevant spectral range from 400 nm to 700 nm.

[0132] The sharp spectral peaks of the spectra of the luminescent lamps illustrated in Figures 3D to 3F cannot be resolved in the spectral reconstruction. However, the obtained reconstructed spectra can be used to identify the type of light sources occurring within the ambient light.

[0133] As for the LED spectra of Figure 3G to 31, the spectral reconstruction provides a good approximation except for the2025PF00276 March 12, 2026

[0134] P2025, 0183 WO N 20

[0135] sharp peak of the primary light of the LED in the short wavelength range of the emission spectrum.

[0136] Figures 4A and 4B as well as Figures 5A to 51 illustrate the impact of a display 18 if the optical sensor 1 is located underneath the display 18 as described in connection with Figure IE.

[0137] As shown in Figure 4C, the transmittance T amounts to a few percent, wherein the transmittance strongly decreases towards shorter wavelengths. This results in a significant decrease of the sensitivity of the detection channels 2, as illustrated in Figure 4A.

[0138] However, the optical sensor 1 still allows for a good approximation of the color matching functions 3X, 3Y, 3Z for radiation with wavelengths above 450 nm as illustrated in Figure 4B.

[0139] The spectral reconstructions illustrated in Figures 5A to 51 are based on the same spectra of the ambient light but consider the transmittance of the display. Curves 51 represent the spectrum of the ambient light. Curves 52 represent the nominal reconstructed spectra and curves 53 represent the reconstructed spectra considering process-related fluctuations as described in connection with Figures 3A to 3I.

[0140] Figures 5A to 51 illustrate that the optical sensor 1 can be used for an optical reconstruction of ambient light even if it is located underneath a display.

[0141] For example, the signal of the optical sensor 1 may be used to adapt the display properties to the ambient light conditions.2025PF00276 March 12, 2026

[0142] P2025, 0183 WO N 21

[0143] As described above, the optical sensor 1 provides good color sensing and spectral sensing capabilities at the same time with a low number of detection channels. By means of substantially spectrally equidistant detection channels 2, an optimized spectral independence of the detection channels can be obtained wherein the detection channels taken together may homogeneously cover the entire visible spectral range. In addition, a substantially constant combined spectral sensitivity can be obtained by means of a linear combination of the sensitivities of the three detection channels of the first set of detection channels together with the first and second additional detection channels. Further, the optical sensor is robust against process-induced fluctuations, so that a high reliability of the optical sensor can be obtained.

[0144] The present application claims priority to German patent application 10 2025 111 755.1, the disclosure of which is hereby incorporated by reference in its entirety.

[0145] The invention described herein is not restricted by the description given with reference to the exemplary embodiments. Rather, the invention encompasses any novel feature and any combination of features, including in particular any combination of features in the claims, even if this feature or this combination is not itself explicitly indicated in the claims or exemplary embodiments.2025PF00276 March 12, 2026

[0146] P2025, 0183 WO N - 22 -

[0147] References

[0148] 1 optical sensor

[0149] 10 electronic device

[0150] 11 sensor chip

[0151] 12 sensor package

[0152] 13 aperture

[0153] 14 substrate

[0154] 15 photosensitive area

[0155] 16 bonding wire

[0156] 17 filter

[0157] 18 display

[0158] 19 ambient light

[0159] 2 detection channel

[0160] 21X first detection channel of first set of detection channels

[0161] 21Y second detection channel of first set of detection channels

[0162] 21Z third detection channel of first set of detection channels

[0163] 22A first additional detection channel

[0164] 22B second additional detection channel

[0165] 23 combined spectral sensitivity

[0166] 23R reference combined spectral sensitivity

[0167] 3X color matching function x̄(λ)

[0168] 3Y color matching function ȳ(λ)

[0169] 3Z color matching function z̄(λ)

[0170] 35 signal

[0171] 41 spectrum of ambient light

[0172] 42 reconstructed nominal spectrum

[0173] 43 reconstructed spectrum considering fluctuations 51 spectrum of ambient light

[0174] 52 reconstructed nominal spectrum2025PF00276 March 12, 2026

[0175] P2025, 0183 WO N - 23 - 53 reconstructed spectrum considering fluctuations

Claims

2025PF00276 March 12, 2026P2025, 0183 WO N - 24 -Claims1. An optical sensor ( 1 ) with a plurality of detection channels, wherein- the detection channels (2 ) each comprise a photosensitive area ( 15) and a filter ( 17 ) to define a spectral sensitivity of the respective detection channel (2 );- the detection channels (2 ) comprise a first set of detection channels with three detection channels (21X, 21Y, 21Z) configured to approximate the three CIE1931 color matching functions x̄(λ), ȳ(λ), and z̄(λ) (3X, 3Y, 3Z);- the plurality of detection channels (2 ) comprises a first additional detection channel (22A) with a wavelength of maximum sensitivity between the maxima of the color matching functions z̄(λ) and ȳ(λ);- the plurality of detection channels comprises a second additional detection channel (22B) with a wavelength of maximum sensitivity larger than the maximum of the color matching function x̄(λ);- the three detection channels of the first set of detection channels (21X, 21Y, 21Z), the first additional detection channel (22A), and the second additional detection channel (22B) taken together are arranged in a spectrally equidistant manner with a tolerance of at most 20 nm.

2. The optical sensor according to claim 1,wherein an average distance between the three detection channels of the first set of detection channels (21X, 21Y, 21Z), the first additional detection channel (22A), and the second additional detection channel (22B) taken together is in a range from 40 nm to 60 nm.

3. The optical sensor according to claim 1 or 2,2025PF00276 March 12, 2026P2025, 0183 WO N - 25 -wherein the first additional detection channel (22A) has a sensitivity with a full width at half maximum in a range from 50 nm to 70 nm.

4. The optical sensor according to any one of the preceding claims,wherein the wavelength of maximum sensitivity of the first additional detection channel (22A) is in a range from 480 nm to 520 nm.

5. The optical sensor according to any one of the preceding claims,wherein the second additional detection channel (22B) has a sensitivity with a full width at half maximum in a range from 60 nm to 80 nm.

6. The optical sensor according to any one of the preceding claims,wherein the wavelength of maximum sensitivity of the second additional detection channel (22B) is in a range from 630 nm to 680 nm.

7. The optical sensor according to any one of the preceding claims,wherein the optical sensor ( 1 ) comprises exactly five detection channels (2 ) with wavelengths of maximum sensitivity in a range from 400 nm to 700 nm.

8. The optical sensor according to any one of the preceding claims,wherein the optical sensor ( 1 ) is configured to approximate the color matching function x̄(λ) by means of a linear2025PF00276 March 12, 2026P2025, 0183 WO N - 26 -combination of the sensitivities of two detection channels of the first set of detection channels (21X, 21Y, 21Z).

9. The optical sensor according to any one of the preceding claims,wherein the wavelengths of maximum sensitivity of the first set of detection channels (21X, 21Y, 21Z) each differ from the maximum of the closest color matching function (3X, 3Y, 3Z) by at most 15 nm.

10. The optical sensor according to any one of the preceding claims,wherein the optical sensor ( 1 ) is configured to provide a combined spectral sensitivity (23) by means of a linear combination of the sensitivities of the three detection channels (21X, 21Y, 21Z) of the first set of detection channels, the first additional detection channel (22A), and the second additional detection channel (22B), wherein the combined spectral sensitivity is constant at least in a range from 470 nm to 620 nm with a tolerance of at most 20 %.

11. The optical sensor according to any one of the preceding claims,wherein the optical sensor ( 1 ) is configured to perform a spectral reconstruction of an ambient light ( 19).

12. The optical sensor according to any one of the preceding claims,wherein the optical sensor ( 1 ) is configured to perform a light source analysis of an ambient light ( 19).

13. An electronic device ( 10) comprising an optical sensor ( 1 ) according to any one of the preceding claims.2025PF00276 March 12, 2026P2025, 0183 WO N - 27 -14. The electronic device according to claim 13,wherein the electronic device ( 10 ) comprises a display ( 18 ).

15. The electronic device according to claim 14,wherein the optical sensor ( 1 ) is arranged behind the display ( 18 ) in a top view onto the display ( 18 ).

Images