Spectral light sensor and corresponding sensing method

Abstract

It is an object of the present invention to provide a cost-effective and simple light sensor (2) with red, green and blue optical channels, the light sensor (2) having high sensing accuracy and stability at varying angles of incidence, in particular for illuminance and color temperature measurements. To this end, the invention proposes a light sensor (2) with a red channel comprising at least one main red photodiode (20) with a first filter stack comprising a UV-IR blocking interference filter (8) and a red absorption filter (24), and at least one complementary photodiode (22) with a second filter stack comprising a UV-IR blocking interference filter (8) and a red absorption filter (24), the second filter stack comprises an interference bandpass filter (26) and an absorption filter, both the primary red photodiode (20) and the supplementary photodiode (22) being fed into a common analog ALS engine (30) or into an evaluation unit configured to add their respective responses to form a red channel output (34), such that the response of the complementary photodiode (22) at least partially compensates for a loss of the response of the main red photodiode (20) with respect to the varying angle of incidence of the incident light.

Description

Technical Field

[0001] The present invention relates to a spectral light sensor having a red optical channel, a green optical channel, and a blue optical channel. The present invention also relates to a corresponding sensing method. Background Art

[0002] Existing light sensors having red, green, blue (RGB) and, if applicable, a clear optical channel are susceptible to inaccurate sensing due to an angular offset (i.e., when the angle of the incident light relative to the optical axis changes over time or relative to a calibrated or reference alignment). Summary of the Invention

[0003] It is an object of the present invention to provide a cost-effective and simple light sensor having RGB optical channels, which has high sensing accuracy and stability at varying angles of incidence, particularly for illuminance and color temperature measurements. A corresponding sensing method will also be given.

[0004] Regarding the light sensor, the object is achieved by a light sensor according to claim 1. The corresponding method is specified in claim 8.

[0005] Accordingly, there is a light sensor having a red optical channel, a green optical channel, and a blue optical channel, the red channel including at least one main red photodiode having a first filter stack and at least one supplementary photodiode having a second filter stack, the first filter stack including a UV-IR blocking interference filter and a red absorption filter, the second filter stack including an interference bandpass filter and an absorption filter, both the main red photodiode and the supplementary photodiode being fed into a common analog ALS engine or a common evaluation unit configured to add their respective responses to form a red channel output, such that the response of the supplementary photodiode compensates at least in part for the loss of the response of the main red photodiode with respect to a varying angle of incidence of the incident light.

[0006] In short, the light sensor according to the present invention has at least two pixels having different filter combinations (and thus different spectral responses) fed into the same red channel output. The supplementary photodiode increases the response to the red channel, which compensates for the loss of the response with respect to the angle due to the cut-off wavelength shift of the interference filter.

[0007] In other words, the filter stack (including an absorption filter and an interference filter) on the supplementary photodiode uses a unique interference filter, which is preferably spectrally shifted at the same rate as the UV-IR blocking filter used on the main red channel photodiode. Thus, the filter stack on the supplementary photodiode is designed to increase the response with respect to angle, which matches the loss of the response of the filter stack on the main red channel photodiode with respect to angle.

[0008] This enables accurate and stable illuminance and color temperature measurements at varying incident angles, which is an important improvement especially for applications such as display management and enhanced camera devices widely used in mobile devices such as smart phones.

[0009] In addition to the solved problem of angular shift and the achieved stable color channel ratio when changing the incident angle, the combined absorption filter stack and interference filter stack also offer several other advantages:

[0010] ● Low-cost components

[0011] ● Low-cost production process

[0012] · Zero increase in device height

[0013] · Low complexity

[0014] · Easy system integration

[0015] · No field-of-view limitation

[0016] · No loss of sensitivity

[0017] In particular, since no encapsulation holes are required, the present invention enables the use of a lower-cost encapsulation. In addition, since no diffuser is required, the present invention enables a lower-cost system design.

[0018] In a preferred embodiment, the absorption filter of the second filter stack is a green absorption filter. Preferably, the green absorption filter has a transmittance maximum in the range of 500 nm to 550 nm and preferably has a falling edge in the visible light region.

[0019] Generally, there are also other available absorption filters, such as CMY (cyan, magenta, yellow), where cyan and magenta may be used. However, for RGB sensors, green is the most cost-effective.

[0020] Furthermore, preferably, the interference bandpass filter has a passband with a lower wavelength limit in the range of 525 nm to 645 nm, particularly a lower wavelength limit of 585 nm, with respect to perpendicularly incident light. Preferably, the passband has an upper wavelength limit in the range of 600 nm to 720 nm, and in a preferred example, an upper wavelength limit of 685 nm, with respect to perpendicularly incident light.

[0021] Advantageously, the spectral shift of the interference bandpass filter response with respect to the incident angle matches the spectral shift of the UV-IR blocking interference filter response.

[0022] Advantageously, each of the green channel and the blue channel includes a photodiode having a filter stack including a UV-IR blocking interference filter and a green or blue absorption filter.

[0023] In useful applications, a device having a light sensor of the above type, particularly a mobile phone, a tablet computer, a portable computer, a wearable device, a television set, etc., is configured to sense ambient light and / or to determine the relevant color temperature and / or for image processing of a camera device. The present invention enables better display (color) quality, better picture (color) quality, and / or better relevant color temperature (CCT) sensing accuracy.

[0024] A corresponding method for spectral sensing of light (preferably ambient light) is based on a light sensor having a red optical channel, a green optical channel, and a blue optical channel. The red channel includes at least one main red photodiode having a first filter stack and at least one supplementary photodiode having a second filter stack. The first filter stack includes a UV-IR blocking interference filter and a red absorption filter, and the second filter stack includes an interference bandpass filter and an absorption filter. Among them, the main red photodiode response and the supplementary photodiode response are combined, particularly added, to form the red channel output, so that the supplementary photodiode response at least partially compensates for the loss of the main red photodiode response with respect to the incident angle of the incident light.

[0025] What has been described regarding the device can be similarly applied to the method, and thus there is no need to repeat it here. Method embodiments and details have counterparts in the device, and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Preferred embodiments of the present invention will now be discussed with reference to the accompanying drawings.

[0027] Figure 1 A schematic cross-sectional view of a conventional light sensor having RGBC (red-green-blue-clear) optical channels is shown.

[0028] Figure 2 Shown at a fixed incident angle withFigure 1 Transmittance graphs related to the various filter responses (i.e., RGB and UV-IR filter transmission curves) of different components of the optical sensor.

[0029] Figure 3 Shows the response graphs related to the various filter transmittances (i.e., normalized RGB output) of the entire optical sensor at a fixed incident angle. Figure 1 Transmittance graphs related to the various filter responses (i.e., normalized RGB output) of different components of the optical sensor.

[0030] Figure 4 Shows Figure 1 The angular dependence or shift of the UV-IR filter response of the optical sensor.

[0031] Figure 5 Shows Figure 1 The angular dependence or shift of the red and blue channel responses of the optical sensor.

[0032] Figure 6 Shows an optical sensor with an upstream diffuser.

[0033] Figure 7 Shows an optical sensor with an upstream optical aperture.

[0034] Figure 8 Shows a photodiode with an exemplary filter stack, which is used as a supplementary photodiode combined with the optical sensor according to Figure 1 the optical sensor.

[0035] Figure 9 Schematically shows an improved red channel measurement device for an optical sensor using the supplementary photodiode according to Figure 8 the supplementary photodiode.

[0036] Figure 10 Shows the various spectral responses for different incident angles related to the supplementary photodiode according to Figure 8 the supplementary photodiode and its respective filter components.

[0037] Figure 11 Shows the spectral red channel response of an improved optical sensor having a main red photodiode and a supplementary photodiode according to Figure 8 the supplementary photodiode for different incident angles.

[0038] Figure 12 Shows the spectral blue channel response and spectral red channel response of an improved optical sensor having a main red photodiode and a supplementary photodiode according to Figure 8 the supplementary photodiode for different incident angles.

[0039] Figure 13Shows the ratio of the blue channel response to the red channel response (angle response under different types of light sources) of a conventional optical sensor and an improved optical sensor with respect to the incident angle. DETAILED DESCRIPTION

[0040] Figure 1 Shows a schematic cross - sectional view of an optical sensor 2 having RGBC (Red - Green - Blue - Clear) optical channels, also known as an RGBC sensor. The optical sensor 2 includes a plurality of optical pixels arranged in an array or matrix configuration in a top view (along the optical path or optical axis 4). Each optical pixel includes a photodiode (PD) 6, a UV - IR blocking interference filter 8 (in particular, a coating), and either a color absorption filter 10 (in particular, a coating) or a transparent cover 12 (in particular, a coating). More precisely, a first group of pixels is assigned a red absorption coating, a second group of pixels is assigned a green absorption coating, a third group of pixels is assigned a blue absorption coating, and an optional fourth group of pixels is assigned a (colorless) transparent cover. Alternatively, for transparent pixels, there may be no coating at all above the UV - IR blocking interference filter 8. In terms of layers, at the bottom is the photodiode layer, in the middle is the UV - IR blocking layer, and at the top is the RGBC mask 14. Generally, there is a substrate layer below the photodiode layer, but it is not shown here.

[0041] Generally, the UV - IR layer can be an intermediate layer or a top layer. Similarly, the RGBC layer can be an intermediate layer or a top layer.

[0042] The clear channel is optional. That is, in a simple RGB optical sensor, there are no transparent pixels. The present invention applies to both RGB optical sensors and RGBC optical sensors.

[0043] The UV - IR blocking interference filter or coating can be simply referred to as a UV - IR filter, and the RGB absorption filter or coating can be simply referred to as an RGB filter.

[0044] In Figure 2 shows the spectral transmittance of the various components of the optical sensor 2, i.e., the transmittance expressed as a percentage (%) relative to the wavelength of the incident light expressed in nm.

[0045] In the graph, the corresponding transmittances for each of the RGB absorption filters 10 or coatings are shown. The transmittance curve for the blue absorption coating has a first prominent maximum at approximately 450 nm, the corresponding first maximum for the green absorption coating is at approximately 530 nm, and the curve representing the effect of the red absorption coating has a first maximum at approximately 600 nm. Towards longer wavelengths, in the infrared (IR) region, all three curves show an increasing behavior, which means that the RGB color coatings are substantially transmissive for IR light. To a lesser extent, this is also true for shorter wavelengths in the ultraviolet (UV) region. The optional transparent coating, if present, is substantially transmissive over the entire wavelength range.

[0046] In addition, Figure 2 The figure in shows a typical transmittance curve for the UV-IR blocking interference filter 8. In terms of transmittance, this filter or coating shows a band-pass behavior, producing a high transmittance in the visible light range (approximately from 400 nm to 700 nm) and low (almost zero) transmittance below and above the visible light range. That is, light with wavelengths in the UV and IR ranges is blocked, while visible light is allowed to pass through, hence the name UV-IR blocking filter. Typically, such a filter is designed as an interference filter.

[0047] Each photodiode 6 of each optical channel has its own spectral response behavior (not shown here). The wavelength at which the photodiode 6 has a maximum response depends on the photodiode structure. The example shown here has a maximum at approximately 750 nm, with relatively gentle attenuation towards lower and higher frequencies.

[0048] For each optical channel in the optical channel of the light sensor 2, the overall spectral response is obtained by combining the responses and transmittances of the individual components, i.e., either the photodiode 6, the UV-IR blocking interference filter 8, and one of the RGB color absorption filters 10 or the transparent cover 12. Mathematically, for each wavelength of interest, the corresponding response values are multiplied by each other to obtain Figure 3 the resulting graph in. The obtained spectral responses for each of the RGB channels are visualized through three corresponding curves (the combined response of the UV-IR blocking filter 8 and the photodiode 6 is also shown). Specifically, the normalized response expressed as a percentage (%) is given according to the wavelength expressed in nm. Although approximately maintaining the original positions of the transmittance maxima of the RGB curves according to Figure 1 the overall effect of the UR-IV blocking filter 8 is clearly visible, as the transmittance in the UV and IR ranges is almost zero.

[0049] In summary, color sensors typically use red, green, and blue (RGB) absorption filters 10. However, the RGB absorption filters 10 allow light in the IR range and the UV range to pass through, which is undesirable. Therefore, the RGB absorption filters 10 need to be coupled with a UV-IR blocking interference filter 8 to block the IR and UV portions of the incident light.

[0050] Problems associated with Figure 1 conventional light sensor designs arise from the fact that the UV-IR blocking interference filter 8 has a transmittance characteristic that depends on the angle of incidence (AoI) of the incident light. Strictly speaking, the transmittance plot of the UV-IR filter and the resulting response plots of the RGB channels of the light sensor 2 are only valid for a fixed reference value of AoI = 0°, where the AoI is given with respect to the optical axis 4. For other AoI values, the corresponding response curves are offset with respect to the reference curve.

[0051] This angular offset originating from the UV-IR blocking interference filter 8 can be clearly seen in Figure 4 where the spectral response (combined with the photodiode response) of the UV-IR blocking interference filter 8 is given as the normalized response in percentage (%) with respect to the wavelength in nm for five different AoI values ranging from 0° to 75°.

[0052] Figure 5 is a similar plot showing the angular offset and angular-dependent flattening of the transmittance curves for the red and blue channels of the conventional light sensor 2 for Figure 1 Specifically, for two different AoI values (i.e., 0° and 60°), the normalized response in percentage (%) of the red and blue channels with respect to the wavelength in nm is given.

[0053] The red channel has an angular offset similar to that of the UV-IR blocking interference filter 8. The blue and green channels, especially the green channel, are less affected. This can be explained as follows: Each RGB channel is formed in combination with the UV-IR blocking interference filter 8. In other words, the UV-IR blocking interference filter 8 is common to the RGB channels and the transparent channel (if there is a transparent channel), and thus affects them in a similar manner. In particular, for higher AoI values, the peak height of the response curve is reduced. This height reduction is mainly due to the fact that the effective sensing area of the photodiode 6 decreases at high angles. In addition, as the angle increases, there is a left shift (towards lower wavelengths) from the UV-IR blocking interference filter 8. However, since the transmission peak in the red color range narrows at high incident angles, the UV-IR blocking interference filter 8 has the most prominent or significant effect on the red channel. For the green channel (not shown), the effect is less prominent, and even more so for the blue channel. Therefore, the ratio of the red channel response to the blue channel response is particularly affected.

[0054] This behavior is particularly disadvantageous for sensing applications in which the outputs of the different channels of the light sensor 2 are compared or correlated with each other. In particular, this behavior results in inaccurate results for illuminance (usually measured in Lux) or correlated color temperature (CCT) estimation.

[0055] In summary, the upper cut-off frequency of the UV-IR blocking interference filter 8 depends on the incident angle of the light. The UV-IR blocking interference filter 8 also sets the cut-off frequency of the response of the red channel, so this cut-off frequency also depends on the incident angle. Therefore, the larger the angle, the more disproportionate the reduction in the response of the red channel is compared to the reduction in the response of the blue channel. This is particularly disadvantageous for CCT performance and similar applications, in which ideally the ratio of the red channel to blue channel response should remain flat (i.e., constant) with respect to the angle.

[0056] Figure 6 A first possible remedy for the problem is shown. The solution includes a diffuser 16 placed in the path of the incident light. The light rays exiting the diffuser 16 are statistically distributed with respect to their direction, regardless of the incident angle of the incident light, thereby creating fixed illumination conditions for the light sensor 2 (exemplarily shown as arranged on a substrate).

[0057] Problems associated with this method include the high cost of the diffuser 16, the high complexity of the integration of the diffuser 16, and a significant reduction in sensitivity (high-quality diffusers 16 typically have a transmittance of less than 50%).

[0058] Figure 7Shows a second possible remedy for the said problem. The solution includes an optical aperture 18 placed in the path of the incident light, which aperture limits the field of view (FoV) with respect to the light sensor 2 arranged further down in the optical path. In other words, the optical aperture 18 blocks light with a high angle of incidence and only allows light with an angle of incidence (AoI≈0) that is almost zero to pass through and reach the light sensor 2. In an example, the optical aperture 18 is a small hole or opening in a light-blocking opaque or non-transparent material or other light-transmitting or transparent area.

[0059] Problems associated with this method include an increase in the height of the device or the system height, a reduction in the FoV, and a significant reduction in sensitivity due to the reduction in the FoV.

[0060] To overcome these problems, a new sensor design is proposed that combines Figure 1 In Figure 8 And Figure 9 Schematically shown. The key point is that in addition to the conventional red photodiode (referred to as the main red photodiode 20), a supplementary photodiode 22 increases the response to the red channel to compensate for and aims to match the blue channel response that depends on the angle of incidence.

[0061] The main red photodiode 20 is constructed as described above. That is, there is a UV-IR blocking interference filter 8 (especially a coating) arranged on the photodiode 6. On top of this filter, there is a red absorption filter 24 (especially a coating). Thus, the main red photodiode 20 has the spectral response described above, which does not need to be repeated here. The various layers or coatings are preferably stacked on top of each other without any gaps between them and without any optically active intermediate layers, although there may be optically irrelevant adhesive layers, etc.

[0062] In principle, the order of the UV-IR blocking interference filter 8 and the red absorption filter 24 can be interchanged without affecting the spectral response. However, in practice, it is advantageous to first apply the UV-IR blocking interference filter 8 as a coating on the photodiode 6 and then apply the red absorption filter 24 on top.

[0063] On the other hand, the supplementary photodiode 22 is constructed as schematically shown in Figure 8 A dedicated interference band-pass (BP) filter 26 (especially a coating) is arranged on the photodiode 6. On top of this filter, there is an absorption filter 28 (especially a coating), especially a green absorption filter.

[0064] Here too, in principle, the order of the filters in the filter stack can be interchanged without affecting the spectral response. However, in practice, it is advantageous to first apply the interference bandpass filter 26 as a coating on the photodiode 6 and then apply the (green) absorption filter 28 on top. Similarly, the various layers or coatings are preferably stacked on top of each other without any gaps therebetween and without any optically active intermediate layers, although there may be optically irrelevant adhesive layers and the like.

[0065] The effect of the filter stack can be understood from Figure 10 the three diagrams in

[0066] In the top diagram, on the one hand, the spectral transmittance of the green absorption filter 28 is indicated for AoI = 0° (i.e., normal incidence of light). As expected, the spectral curve (labeled as just green), which is a combination of the green filter spectral transmittance and the photodiode 6 spectral response, has a first maximum near 530 nm, corresponding to the green spectral region, and relatively steep attenuation or drop-off on both sides. In the IR region, from approximately 700 nm onwards, the green transmittance curve rises again and has a second, slightly broader maximum centered near 850 nm.

[0067] On the other hand, also for AoI = 0°, the spectral transmittance of the interference bandpass filter 26 is indicated. As the name implies, a bandpass filter is one that allows wavelengths within a certain range (referred to as the passband) to pass through and rejects (or attenuates) wavelengths outside that range. In this particular case, the lower or cut-off wavelength of the passband is near 585 nm (thus labeled as 585BP), and the upper or cut-off wavelength is near 660 nm, centered near 630 nm. In other words, the passband for AoI = 0° lies at the minimum of the green transmittance curve between the first and second maxima and is similar in shape and position to the Figure 3 red absorption peak for the main red photodiode according to

[0068] In the middle diagram, the green transmittance curve and the interference filter passband for AoI = 60° are shown. Generally, the green transmittance curve is slightly flatter (with less prominent peaks) than the 0° corresponding curve, which is mainly due to the smaller effective incident area on the photodiode because of the oblique incidence angle. The same height reduction occurs for the passband of the interference bandpass filter 26. More importantly, the passband of the interference bandpass filter 26 has shifted to the left, towards lower wavelengths, and now overlaps and almost covers the green absorption peak of the green absorption filter 28.

[0069] The combined effect of the filter stack on the supplementary red photodiode 22 is obtained by multiplying the individual contributions (i.e., the contributions from the interference bandpass filter 26 and the green absorption filter 28 (and photodiode 6)). For two different angles of incidence, namely AoI = 0° and AoI = 60°, in Figure 10 the bottom chart of shows the resulting spectral response of the supplementary red photodiode 22, including the effect of the filter stack. It can be seen that for 0°, the response of the supplementary red photodiode 22 is almost zero and can therefore be neglected. However, for larger angles such as 60°, the response curve shifts to the left, towards lower wavelengths, and has a non-negligible contribution in the green range with a peak around 550 nm.

[0070] As indicated above in connection with Figure 9 both the main red photodiode 20 and the supplementary photodiode 22 feed their respective outputs into a common analog ALS engine 30 (ALS = ambient light sensor) that generates a combined output based on the two signal inputs. For example, the analog ALS engine 30 can generate a sum value or an arithmetic mean or a weighted sum value or combined value in some other way based on the additive contributions from the respective signals mentioned above. The analog sum signal can be fed into an analog-to-digital converter (ADC) 32 to provide a digital red channel output 34.

[0071] In a generalized variant, the main red photodiode 20 and the supplementary photodiode 22 are not necessarily connected to a common analog ALS engine 30. Instead, the supplementary diode 22 can be an independent channel with its own dedicated analog ALS engine and ADC. Thus, software implemented in an evaluation unit or a control unit can access the devices to obtain the results from the main photodiode 20 and the supplementary photodiode 22 and perform mathematical compensation in the software. For example, the mathematical compensation can be a simple linear addition by applying different gains to the supplementary channel or a weighted compensation based on, for example, the detected IR ratio in the ambient light, or any customized compensation based on specific characteristics in the actual product (such as curve compensation, look-up tables, etc.). Additionally or alternatively, the supplementary photodiode 22 can be fed as an independent input into a deep learning network.

[0072] In summary, the filter stack on the supplementary photodiode 22 includes an absorption filter 28 (preferably green) combined with a dedicated interference bandpass filter 26 that spectrally shifts with angle at the same or at least a similar rate as the UV-IR blocking interference filter 8 used on the main red photodiode 20. Thus, the filter stack on the supplementary photodiode 22 is designed to increase the response as the incident angle increases such that the increased response matches the simultaneous loss of response with angle of the filter stack (red absorption filter 24 and UV-IR blocking interference filter 8) on the main red photodiode 20. Thus, the supplementary red photodiode 22 adds a response to the red channel that ideally matches proportionally the relative increase in the blue channel response with angle.

[0073] This is shown in Figure 11 and Figure 12 . In Figure 11 , the resulting red channel spectral response according to the combined main red photodiode 20 and supplementary red photodiode 22 is shown for five different AoI values ranging from 0° to 75°. In Figure 12 , the modified or enhanced red channel response and the conventional blue channel response are shown together for two different angles, namely 0° and 60°. While for 0°, the shapes of the two curves are almost the same as those of the conventional light sensor in Figure 5 , for larger angles (such as 60°), the loss in peak height of the red channel response relative to the blue channel response is not as drastic as in Figure 5 . In the example, even for higher angles, the red channel peak still dominates relative to the blue channel peak. In other words, the (new) improved red channel response with the supplementary red photodiode 22 shows a smaller variation with angle compared to the conventional red channel without the supplementary red photodiode 22.

[0074] This result is further shown in Figure 13 , where each of the four graphs shows the ratio of the blue channel response to the red channel response with respect to the varying angle (from 0° to 75°), first for the conventional red channel and second for the new red channel. The upper left graph shows the said angle response for sunlight, the upper right graph is obtained from fluorescent lighting, the lower left graph is related to warm white LEDs, and the lower right graph is related to incandescent lamps. In all four cases, the angle response ratio of the improved sensor is substantially flat or constant compared to the original sensor design. This provides various advantages for sensing applications that require accuracy and angle stability, especially for applications for illuminance and color temperature measurement.

[0075] While the present invention provides the advantage of generally not requiring an upstream diffuser 16 or an optical aperture 18, each of the upstream diffuser 16 or the optical aperture 18 (either alone or in combination) may still be present to achieve optimal color stability.

[0076] List of reference numerals

[0077] Light sensor 2

[0078] Optical axis 4

[0079] Photodiode 6

[0080] UV-IR blocking interference filter 8

[0081] Color absorption filter 10

[0082] Transparent cover 12

[0083] RGBC mask 14

[0084] Diffuser 16

[0085] Optical aperture 18

[0086] Main red photodiode 20

[0087] Supplemental photodiode 22

[0088] Red absorption filter 24

[0089] Interference bandpass filter 26

[0090] Absorption filter 28

[0091] Analog ALS engine 30

[0092] Analog-to-digital converter 32

[0093] Red channel output 34

Claims

1. A light sensor (2) having a red optical channel, a green optical channel, and a blue optical channel, wherein the red channel includes at least one main red photodiode (20) having a first filter stack and at least one supplementary photodiode (22) having a second filter stack, the first filter stack including a UV-IR blocking interference filter (8) and a red absorption filter (24), the second filter stack including an interference bandpass filter (26) and an absorption filter (28), and both the main red photodiode (20) and the supplementary photodiode (22) are fed into a common analog ALS engine (30) configured to add their respective responses to form a red channel output (34) or into an evaluation unit, such that the response of the supplementary photodiode (22) at least partially compensates for the loss of the response of the main red photodiode (20) with respect to the varying incident angle of the incident light.

2. The optical sensor (2) according to claim 1, wherein, The absorption filter (28) of the second filter stack has a descending edge in the visible light region.

3. The optical sensor (2) according to claim 1 or 2, wherein, The absorption filter (28) of the second filter stack is a green absorption filter.

4. The optical sensor (2) according to any one of the preceding claims, wherein, The interference bandpass filter (26) has a passband with a lower wavelength limit in the range of 552 nm to 645 nm with respect to perpendicularly incident light.

5. The optical sensor (2) according to claim 4, wherein, The passband has an upper wavelength limit in the range of 600 nm to 720 nm with respect to perpendicularly incident light.

6. The optical sensor (2) according to any one of the preceding claims, wherein, The spectral shift of the response of the interference bandpass filter (26) with respect to the incident angle matches the spectral shift of the response of the UV-IR blocking interference filter (8).

7. The optical sensor (2) according to any one of the preceding claims, wherein, The green channel and the blue channel each include a photodiode (6) having a filter stack, the filter stack including a UV-IR blocking interference filter (8) and a green or blue color absorption filter (10).

8. A method for spectral sensing of light by a light sensor (2) having a red optical channel, a green optical channel, and a blue optical channel, wherein the red channel includes at least one main red photodiode (20) having a first filter stack and at least one supplementary photodiode (22) having a second filter stack, the first filter stack includes a UV-IR blocking interference filter (8) and a red absorption filter (24), the second filter stack includes an interference bandpass filter (26) and an absorption filter (28), wherein, The response of the main red photodiode (20) and the response of the supplementary photodiode (22) are combined, in particular added, to form a red channel output (34), such that the response of the supplementary photodiode (22) at least partially compensates for the loss of the response of the main red photodiode (20) with respect to the varying incident angle of the incident light.

9. The method according to claim 8, wherein Before digitization, the response of the main red photodiode (20) and the response of the supplementary photodiode (22) are combined in a common analog ALS engine (30).

10. The method according to claim 8, wherein, After digitization, the response of the main red photodiode (20) and the response of the supplementary photodiode (22) are combined by a software routine of a relevant evaluation unit.

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