SPECTRAL LIGHT SENSOR AND CORRESPONDING DETECTION METHOD

Abstract

An objective of the present invention is to provide a cost-effective and simple light sensor (2) with red, green and blue optical channels, which has high detection accuracy and stability at varying angles of incidence, especially for illuminance and color temperature measurements.For this purpose, the invention proposes a red channel light sensor (2) comprising at least one primary red photodiode (20) with a first filter stack and at least one additional photodiode (22) with a second filter stack, wherein the first filter stack comprises a UV-IR blocking interference filter (8) and a red absorption filter (24) and the second filter stack comprises an interference bandpass filter (26) and an absorption filter, wherein the primary red photodiode (20) and the additional photodiode (22) both feed into a common analog ALS engine (30) or into an evaluation unit configured to add their individual responses to form a red channel output (34), such that the response of the additional photodiode (22) at least partially compensates for a loss in the response of the primary red photodiode (20) over a varying angle of incidence of the incident light.

Description

TECHNICAL AREA

[0001] The invention relates to a spectral light sensor with red, green, and blue optical channels. It also relates to a corresponding detection method. BACKGROUND

[0002] Existing light sensors with red, green, blue (RGB) and possibly clear optical channels are susceptible to measurement inaccuracies due to angular shifts, i.e., when the angle of the incident light relative to the optical axis changes over time or relative to a calibration or reference alignment. SUMMARY

[0003] The present invention aims to provide a cost-effective and simple light sensor with optical RGB channels that exhibits high detection accuracy and stability at different angles of incidence, particularly for illuminance and color temperature measurements. A corresponding detection method will also be described.

[0004] With regard to the light sensor, the purpose is fulfilled by a light sensor according to claim 1. The corresponding method is specified in claim 8.

[0005] Accordingly, there is a light sensor with red, green, and blue optical channels, wherein the red channel comprises at least one primary red photodiode with a first filter stack and at least one additional photodiode with a second filter stack, wherein the first filter stack comprises a UV-IR blocking interference filter and a red absorption filter, and the second filter stack comprises an interference bandpass filter and an absorption filter, the primary red photodiode and the additional photodiode both feed into a common analog ALS engine or a common evaluation unit configured to add their individual responses to form a red channel output, such that the response of the additional photodiode at least partially compensates for a loss in the response of the primary red photodiode over a varying angle of incidence of the incident light.

[0006] In short, the light sensor according to the invention has at least two pixels with different filter combinations (and therefore different spectral response sensitivities) that feed into the same red channel output. The additional photodiode adds a response to the red channel that compensates for the loss of response over the angle due to the shift in the cutoff wavelength of the interference filter.

[0007] In other words, the filter stack (consisting of an absorption and an interference filter) on the additional photodiode uses a unique interference filter that preferably shifts spectrally at the same rate as the UV-IR blocking filter on the primary red-channel photodiode. The filter stack on the additional photodiode is therefore designed to increase the response over the angle corresponding to the loss of response over the angle for the filter stack on the primary red-channel photodiode.

[0008] This enables accurate and stable measurements of illuminance and color temperature at different angles of incidence, which is, among other things, an important improvement for display management and camera enhancement applications that are widely used in mobile devices such as smartphones.

[0009] Besides solving the problem of angular shift and achieving stable color channel ratios at changing angles of incidence, the combined absorption and interference filter stack offers further advantages: • Cost-effective components • cost-effective production process • no increase in device height • low complexity • Simple system integration • no restriction of the field of vision • no loss of sensitivity

[0010] In particular, the invention enables the use of more cost-effective packaging, as no packaging opening is required. Furthermore, the invention allows for a more cost-effective system design, as no diffuser is needed.

[0011] In a preferred embodiment, the absorption filter of the second filter stack is a green absorption filter. Preferably, the green absorption filter has a transmission maximum in the range of 500 nm to 550 nm, preferably with a sloping flank in the visible range.

[0012] Generally, other absorption filters exist, such as CMY (cyan, magenta, yellow), where cyan and magenta could be used. However, green is the most cost-effective for an RGB sensor.

[0013] Furthermore, it is preferred that the interference bandpass filter has a passband with a lower wavelength limit in the range of 525 nm to 645 nm, particularly 585 nm, with respect to vertically incident light. Preferably, the passband has an upper wavelength limit in the range of 600 nm to 720 nm, in a preferred example 685 nm, with respect to vertically incident light.

[0014] An advantage is that the spectral shift of the interference bandpass filter across the angle of incidence matches the spectral shift of the UV-IR blocking interference filter.

[0015] The green and blue channels conveniently each consist of a photodiode with a filter stack containing a UV-IR blocking interference filter and either a green or a blue absorption filter.

[0016] In a suitable application, a device, in particular a mobile phone, tablet, portable computer, wearable, television, or the like, is equipped with a light sensor of the aforementioned type for detecting ambient light and / or for determining a correlated color temperature and / or for camera image processing. The invention enables improved display (color) quality, improved image (color) quality, and / or improved detection accuracy of the correlated color temperature (CCT).

[0017] A corresponding method for the spectral detection of light, preferably ambient light, is based on a light sensor with red, green, and blue optical channels, wherein the red channel comprises at least one primary red photodiode with a first filter stack and at least one additional photodiode with a second filter stack, wherein the first filter stack comprises a UV-IR blocking interference filter and a red absorption filter, and the second filter stack comprises an interference bandpass filter and an absorption filter, wherein the response of the primary red photodiode and the response of the additional photodiode are combined, in particular added, to form a red channel output, such that the response of the additional photodiode at least partially compensates for a loss in the response of the primary red photodiode over a varying angle of incidence of the incident light.

[0018] What has been said regarding the device can be applied analogously to the method and therefore need not be repeated here. The embodiments and details of the method correspond to the device, and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Advantageous embodiments of the invention will now be discussed with reference to the accompanying drawings. Fig. Figure 1 shows a schematic sectional view of a conventional light sensor with optical RGBC channels (red-green-blue-clear). Fig. Figure 2 shows a transmission diagram in relation to different filter responses (i.e., RGB and UV-IR filter transmission curves) for different components of the light sensor. Fig. 1 at a fixed angle of incidence. Fig. Figure 3 shows a response diagram in relation to different filter transmissions (i.e., normalized RGB output) of the entire light sensor. Fig. 1 at a fixed angle of incidence. Fig. Figure 4 shows the angular dependence or shift of the UV-IR filter response for the light sensor of Fig. 1. Fig. Figure 5 shows the angular dependence or shift of the response of the red and blue channels for the light sensor of Fig. 1. Fig. Figure 6 shows a light sensor with a diffuser in front of it. Fig. Figure 7 shows a light sensor with an upstream optical aperture. Fig. Figure 8 shows a photodiode with an exemplary filter stack, which is used as an additional photodiode in conjunction with a light sensor according to Fig. 1 can be used. Fig. Figure 9 schematically shows an improved red channel measurement arrangement for a light sensor using an additional photodiode according to Fig. 8. Fig. Figure 10 shows different spectral responses for different angles of incidence in conjunction with an additional photodiode according to Fig. 8 and their individual filter components. Fig. Figure 11 shows the spectral red channel response for different angles of incidence of an improved light sensor with a primary red photodiode and an additional photodiode according to Fig. 8. Fig. Figure 12 shows the spectral blue and red channel responses for different angles of incidence for an improved light sensor with a primary red photodiode and an additional photodiode according to Fig. 8. Fig. Figure 13 shows the relationship between the response of the blue channel and the response of the red channel across the angle of incidence (angle response under different types of light sources) for a conventional and an improved light sensor. DETAILED DESCRIPTION

[0020] Fig. Figure 1 shows a schematic sectional view of a light sensor 2 with optical RGBC (red-green-blue-clear) channels, also called an RGBC sensor. The light sensor 2 comprises a plurality of optical pixels arranged in an array or matrix configuration in the 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 colored absorption filter 10 (in particular a coating) or a clear cover 12 (in particular a coating). More precisely, a first group of pixels has a red absorption layer, a second group of pixels has a green absorption layer, a third group of pixels has a blue absorption layer, and an optional fourth group of pixels has a (uncolored) clear cover.Alternatively, in the case of clear pixels, there may be no coating at all over the UV-IR blocking interference filter 8. Regarding the layers, there is a photodiode layer at the bottom, a UV-IR blocking layer in the middle, and an RGBC mask 14 at the top. Typically, there is a substrate layer below the photodiode layer, but this is not shown here.

[0021] Generally, the UV-IR layer can be a middle or top layer. Similarly, the RGBC layer can be a middle or top layer.

[0022] The clear channel is optional. That is, in a simple RGB light sensor there are no clear pixels. The present invention applies to both an RGB and an RGBC light sensor.

[0023] A UV-IR blocking interference filter or coating can simply be called a UV-IR filter, and the RGB absorption filters or coatings can simply be called RGB filters.

[0024] The spectral transmittance, i.e., the transmittance in % across the wavelength in nm of the incident light, for the individual components of the light sensor 2 is given in Fig. 2 shown.

[0025] The diagram shows the respective transmittance for each of the RGB absorption filters or coatings. The transmittance curve for the blue absorption layer has a first pronounced maximum at approximately 450 nm, the corresponding first maximum for the green absorption layer is at approximately 530 nm, and the curve representing the effect of the red absorption layer has a first maximum at approximately 600 nm. Towards longer wavelengths, in the infrared (IR) range, all three curves show an increasing behavior, which means that the RGB color coatings are generally transparent to IR light. This also applies, to a lesser extent, to shorter wavelengths in the ultraviolet (UV) range. An optional clear coat, if present, is generally transparent to the entire wavelength range.

[0026] Furthermore, the diagram shows in Fig. Figure 2 shows a typical transmission curve for the UV-IR blocking interference filter 8. In terms of transmittance, this filter or coating exhibits bandpass behavior with high transmittance in the visible range (approximately 400 to 700 nm) and low transmittance (near zero) below and above the visible range. This means that light with wavelengths in the UV and IR ranges is blocked, while visible light is transmitted; hence the name UV-IR blocking filter. Such filters are typically designed as interference filters.

[0027] Photodiode 6 of each optical channel has its own spectral response (not shown here). The wavelength at which photodiode 6 reaches its maximum depends on the photodiode's structure. The examples shown here have a maximum at approximately 750 nm, with a relatively gradual decay to lower and higher frequencies.

[0028] For each of the optical channels of the light sensor 2, the overall spectral sensitivity is determined by combining the sensitivity and transmittance of the individual components, i.e., the photodiode 6, the UV-IR blocking interference filter 8, and either the RGB color absorption filter 10 or the clear cover 12. Mathematically, the respective response values ​​for each wavelength of interest are multiplied together, resulting in the diagram in Fig. 3. The resulting spectral sensitivity for each of the RGB channels is illustrated by three corresponding curves (the combined sensitivity of the UV-IR blocking filter 8 and the photodiode 6 is also shown). To be precise, the normalized response is given in % as a function of the wavelength in nm. While the original positions of the transmission maxima of the RGB curves from Fig. Although the overall effect of the UR-IV blocking filter 8 is clearly visible, the transmission in the UV and IR range is almost zero.

[0029] 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 and UV ranges to pass through, which is undesirable. Therefore, the RGB absorption filters 10 must be coupled with a UV-IR blocking interference filter 8 to block the IR and UV components of the incident light.

[0030] One problem with the conventional light sensor design of Fig. 1 results 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 transmission diagram for the UV-IR filter and the resulting response diagram for the RGB channels of the light sensor 2 are only valid for a fixed reference value of AoI = 0°, where the AoI is specified relative to the optical axis 4. For other AoI values, the corresponding response curves are shifted relative to the reference curves.

[0031] This angular shift caused by the UV-IR blocking interference filter 8 is in Fig. 4 clearly shows the spectral response of the UV-IR blocking interference filter 8 (in combination with the response of the photodiode) as a normalized response in % over the wavelength in nm for five different AoI values ​​from 0° to 75°.

[0032] Fig. Figure 5 is a similar diagram showing the angular shift and angle-dependent flattening of the transmission curves for the red and blue channels of the conventional light sensor 2. Fig. Figure 1 shows. To be precise, a normalized response in % across the wavelength in nm is given for the red and blue channels for two different AoI values, namely 0° and 60°.

[0033] The red channel exhibits a similar angular shift to the UV-IR blocking interference filter 8. The blue and green channels, especially the green one, 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 filter 8 is common to the RGB channels and, if present, the clear channel, and therefore affects them similarly. In particular, the peak height of the response curves is reduced at higher angles of incidence (AoI). This reduction in height is primarily due to the photodiode 6, as the effective detection area decreases at high angles. Furthermore, at larger angles, there is a leftward shift of the UV-IR blocking interference filter 8 (towards lower wavelengths).The UV-IR blocking interference filter 8, however, has the strongest effect on the red channel, as the transmittance peak in the red color range narrows at high angles of incidence. This effect is less pronounced for the green channel (not shown) and even less pronounced for the blue channel. Therefore, the ratio between the response of the red channel and the response of the blue channel is particularly affected.

[0034] This behavior is particularly detrimental for sensing applications where the output of the different channels of light sensor 2 is compared or correlated. In particular, it leads to inaccurate results when estimating illuminance (usually measured in lux) or the correlated color temperature (CCT).

[0035] In summary, the upper cutoff frequency of the UV-IR blocking interference filter 8 depends on the angle of incidence of the light. The UV-IR blocking interference filter 8 also determines the cutoff frequency of the red channel's response, which is therefore also dependent on the angle of incidence. Consequently, the response of the red channel decreases disproportionately to the response of the blue channel as the angle of incidence increases. This is particularly disadvantageous for CCT and similar applications, where the ratio between the red and blue channels should ideally remain flat (i.e., constant) across the angle.

[0036] Fig. Figure 6 shows a first possible solution to this problem. The solution consists of a diffuser 16, which is placed in the path of the incident light. The light rays emerging from the diffuser 16 are statistically distributed in their direction, independent of the angle of incidence of the incident light, thus resulting in fixed illumination conditions for the light sensor 2 (here shown by way of example arranged on a substrate).

[0037] Problems with this approach include high costs for the diffuser 16, high complexity in integrating the diffuser 16, and a significant reduction in sensitivity (a good quality diffuser 16 typically has a transmission rate of less than 50%).

[0038] Fig. Figure 7 shows a second possible solution to this problem. The solution includes an optical aperture 18 positioned in the path of the incident light, where the aperture restricts the field of view (FoV) with respect to the light sensor 2 located further down the optical path. In other words, the optical aperture 18 blocks light with high angles of incidence and allows only light with angles of incidence close to zero (AoI ≈ 0) to pass through and reach the light sensor 2. In this example, the optical aperture 18 is a small hole or opening, or otherwise an optically transparent or permeable region in an opaque or non-transparent material.

[0039] Problems with this approach include a greater device or system height, a smaller field of view, and a significant reduction in sensitivity due to the smaller field of view.

[0040] To overcome these problems, a new sensor design is proposed, which is schematically shown in Fig. 8 and Fig. 9 in conjunction with Fig. Figure 1 is shown. The crucial point is that, in addition to a conventional red photodiode (referred to as the primary red photodiode 20), an additional photodiode 22 adds a response to the red channel to compensate for and correct the varying response of the blue channel depending on the angle of incidence.

[0041] The primary red photodiode 20 is constructed as described above. That is, a UV-IR blocking interference filter 8 (in particular a coating) is arranged on a photodiode 6. A red absorption filter 24 (in particular a coating) is located above this filter. The primary red photodiode 20 therefore has the spectral sensitivity described above, which need not be repeated here. The various layers or coatings are preferably stacked on top of each other without gaps and without optically active intermediate layers, although optically irrelevant interconnect layers or the like may be present.

[0042] In principle, the order of the UV-IR blocking interference filter 8 and the red absorption filter 24 can be reversed without affecting the spectral sensitivity. In practice, however, it is advantageous to first apply a UV-IR blocking interference filter 8 as a coating to the photodiode 6 and then the red absorption filter 24 over it.

[0043] The additional photodiode 22, on the other hand, is constructed as shown in Fig. Figure 8 shows a schematic representation. A special interference bandpass filter 26 (in particular a coating) is arranged on the photodiode 6. Above this filter is an absorption filter 28 (in particular a coating), in particular a green absorption filter.

[0044] Here too, the order of the filters in the filter stack can, in principle, be reversed without affecting the spectral sensitivity. In practice, however, it is advantageous to first apply an interference bandpass filter 26 as a coating to the photodiode 6 and then the (green) absorption filter 28 on top of it. Again, the various layers or coatings are preferably stacked on top of each other without gaps and without optically active intermediate layers, although optically irrelevant interconnecting layers or similar may be present.

[0045] The effect of the filter stack can be seen in the three diagrams in Fig. 10. Understand.

[0046] The top diagram shows the spectral transmittance of the green absorption filter 28 for an angle of incidence (AoI) of 0°, i.e., for vertical light incidence. As expected, the spectral curve, which is a combination of the spectral transmittance of the green filter and the spectral sensitivity of the photodiode 6 (labeled "Green Only"), has a first maximum at approximately 530 nm, corresponding to the green spectral range, and a relatively steep drop-off on both sides. In the IR range, from about 700 nm, the green transmittance curve rises again and has a second, somewhat broader maximum around 850 nm.

[0047] On the other hand, the spectral transmittance of the interference bandpass filter 26 is given, also for an AoI = 0°. As the name suggests, the bandpass filter is a filter that transmits wavelengths within a certain range (called the passband) and rejects (or attenuates) wavelengths outside this range. In this particular case, the lower limit or cut-off wavelength of the passband is at about 585 nm (hence the designation 585 BP), and the upper limit or cut-off wavelength is at about 660 nm, with a midpoint at 630 nm. In other words, the passband for an AoI = 0° lies at the minimum of the green transmission curve between the first and second maximums and is similar in shape and position to the red absorption peak from [reference missing]. Fig. 3 for the primary red photodiode.

[0048] The middle diagram shows the green transmission curve and the passband of the interference filter for an angle of incidence (AoI) of 60°. In general, the green transmission curve is somewhat flatter (with less pronounced peaks) than its counterpart at 0°, mainly due to the smaller effective incidence area on the photodiode resulting from the oblique angle of incidence. The same reduction in height is observed 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 with and almost completely obscures the green absorption peak of the green absorption filter 28.

[0049] The combined effect of the filter stack on the additional red photodiode 22 results from the multiplication of the individual contributions, i.e., the interference bandpass filter 26 and the green absorption filter 28 (and also the photodiode 6). The resulting spectral response of the additional red photodiode 22, including the effect of the filter stack, is shown in the bottom diagram of Fig. Figure 10 shows the response curve for two different angles of incidence, namely AoI = 0° and AoI = 60°. It can be seen that at 0° the response of the additional red photodiode 22 is almost zero and therefore negligible. At larger angles such as 60°, however, the response curve is shifted to the left towards shorter wavelengths and exhibits a non-negligible contribution with a peak in the green region around 550 nm.

[0050] As above in connection with Fig. As indicated in Figure 9, both the primary red photodiode 20 and the additional photodiode 22 feed their respective outputs into a common analog ALS engine 30 (ALS = ambient light sensor), which generates a combined output from the two signal inputs. The analog ALS engine 30 can, for example, generate a sum value, an arithmetic mean, or another weighted sum or combination value with additive contributions from the individual signals. The analog sum signal can be fed into an analog-to-digital converter (ADC) 32 to generate a digital red channel output 34.

[0051] In a somewhat generalized version, the primary red photodiode 20 and the additional photodiode 22 do not need to be connected to a common analog ALS module 30. Instead, the additional diode 22 can be an independent channel with its own analog ALS engine and ADC. In this way, software implemented in an evaluation or control unit can access the results from the primary photodiode 20 and the additional photodiode 22 and perform mathematical compensation in software. This could be, for example, a simple linear addition by applying a different gain to the additional channel, a weighted compensation (e.g., based on the IR ratio detected in the ambient light), or any customer-specific compensation (e.g., curved compensation, a lookup table, etc.).) based on the specific characterization in an actual product. Additionally or alternatively, the additional photodiode 22 can be fed into a deep learning network as an independent input.

[0052] In summary, the filter stack on the additional photodiode 22 comprises a (preferably green) absorption filter 28 in combination with a special interference bandpass filter 26, which shifts spectrally over the angle at the same or at least a similar rate as the UV-IR blocking interference filter 8 used on the primary red photodiode 20. The filter stack on the additional photodiode 22 is therefore designed such that the response sensitivity increases with increasing angle of incidence, so that the increasing response sensitivity corresponds to the simultaneous loss of response sensitivity over the angle for the filter stack (red absorption filter 24 and UV-IR blocking interference filter 8) on the primary red photodiode 20.Consequently, the additional red photodiode 22 adds a response to the red channel which, ideally, is proportional to the relative increase in the response of the blue channel across the angle.

[0053] This is in Fig. 11 and Fig. Figure 12 shows the resulting spectral sensitivity of the red channel of the combined primary and additional red photodiodes 20, 22. Fig. Figure 11 shows five different AoI values ​​from 0° to 75°. The modified or improved red channel response is shown together with a conventional blue channel response in Fig. Figure 12 shows curves for two different angles, namely 0° and 60°. While for 0° the shape of both curves is almost identical to the curves of the conventional light sensor in Fig. 5, the loss of peak height of the red channel response relative to the blue channel response is less drastic for larger angles such as 60° than in Fig. 5. In this example, the peak of the red channel remains dominant over the peak of the blue channel even at larger angles. In other words, the (new) improved red channel response with the additional red photodiode 22 shows less change over the angle than the conventional red channel without it.

[0054] This result will be in Fig.Figure 13 further illustrates this by showing the ratio between the response of the blue channel and the response of the red channel at different angles (from 0° to 75°), once for the conventional red channel and once for the new red channel. The upper left diagram shows the angle response for sunlight, the upper right diagram is from fluorescent lighting, the lower left diagram relates to a warm white LED, and the lower right diagram to an incandescent lamp. In all four cases, the angle response ratio of the improved sensor is essentially flat or constant, unlike the original sensor design. This offers several advantages for sensor applications where accuracy and angle stability are required, particularly for illuminance and color temperature measurements.

[0055] The invention offers the advantage that, in general, neither a preceding diffuser 16 nor an optical aperture 18 is required, but each of these elements (alone or in combination) can be present to achieve optimal color stability. LIST OF REFERENCE MARKS 2 light sensors 4 optical axis 6 photodiode 8 UV-IR blocking interference filters 10 colored absorption filters 12 clear covers 14 RGBC mask 16 Diffuser 18 optical aperture 20 primary red photodiodes 22 additional photodiodes 24 red absorption filters 26 Interference bandpass filters 28 absorption filters 30 analog ALS engines 32 Analog-to-Digital Converters 34 Red Channel Exit

Claims

[1] Light sensor (2) with red, green and blue optical channels, wherein the red channel comprises at least one primary red photodiode (20) with a first filter stack and at least one additional photodiode (22) with a second filter stack, wherein the first filter stack comprises 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 (28), wherein the primary red photodiode (20) and the additional photodiode (22) both feed into a common analog ALS engine (30) or into an evaluation unit configured to add their individual responses to form a red channel output (34), such that the response of the additional photodiode (22) at least partially compensates for a loss of response of the primary red photodiode (20) over a varying angle of incidence of the incident light. [2] Light sensor (2) according to claim 1, wherein the absorption filter (28) of the second filter stack has a falling edge in the visible range. [3] Light sensor (2) according to claim 1 or 2, wherein the absorption filter (28) of the second filter stack is a green absorption filter. [4] Light sensor (2) according to 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 vertically incident light. [5] Light sensor (2) according to claim 4, wherein the transmittance range has an upper wavelength limit in the range of 600 nm to 720 nm with respect to vertically incident light. [6] Light sensor (2) according to one of the preceding claims, wherein the spectral shift of the response of the interference bandpass filter (26) over the angle of incidence matches the spectral shift of the response of the UV-IR blocking interference filter (8). [7] The light sensor (2) according to one of the preceding claims, wherein the green and blue channels each comprise a photodiode (6) with a filter stack comprising a UV-IR blocking interference filter (8) and either a green or a blue color absorption filter (10). [8] Method for spectral detection of light using a light sensor (2) with red, green and blue optical channels, wherein the red channel comprises at least one primary red photodiode (20) with a first filter stack and at least one additional photodiode (22) with a second filter stack, wherein the first filter stack comprises a UV-IR blocking interference filter (8) and a red absorption filter (24), and the second filter stack comprises an interference bandpass filter (26) and an absorption filter (28), wherein the response of the primary red photodiode (20) and the response of the additional photodiode (22) are combined, in particular added, to form a red channel output (34), such that the response of the additional photodiode (22) at least partially compensates for a loss in the response of the primary red photodiode (20) over a varying angle of incidence of the incident light. [9] Method according to claim 8, wherein the response of the primary red photodiode (20) and the response of the additional photodiode (22) are combined in a common analog ALS engine (30) prior to digitization. [10] Method according to claim 8, wherein the response of the primary red photodiode (20) and the response of the additional photodiode (22) are combined after digitization by a software routine of an associated evaluation unit.

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