Light detection system

Abstract

The invention relates to a light detection system (1), comprising: - a light emitting device (8) configured to emit light towards a target, - a light detecting device (6), configured to detect light, positioned with a geometrical offset from the light emitting device (8), - a substrate (2), having two surfaces, on one of which the light emitting device (8) and the light detecting device (6) are placed, - a first panel (10), which extends over the substrate (2) on the side of the substrate (2) where the light emitting device (8) and the light detecting device (6) are placed, and - a second panel (12), which is placed between the first panel (10) and the substrate (2) and extending above and at least over the light detecting device (6), and wherein the second panel (12) has an aperture (14, which extends only partly over the light detecting device (6), so that a distance between a center of the aperture (14) and the light emitting device (8) is smaller than the distance between a center of the light detecting device (6) and the light emitting device (8). Furthermore, a corresponding a sensor arrangement and method for manufacturing a light detection system is disclosed.

Description

[0001] LIGHT DETECTION SYSTEM

[0002] DESCRIPTION

[0003] TECHNICAL FIELD

[0004] The present invention relates to a light detection system and a method for manufacturing the same .

[0005] BACKGROUND

[0006] Light detection systems can be proximity detection systems and can also work as a touch sensor or a touch force detection system .

[0007] A proximity sensor deploying photodiodes operates on the principle of light reflection . The sensor emits a beam of light , often infrared, towards the target obj ect . When the obj ect comes within the detection range , the light beam hits the obj ect and gets reflected back .

[0008] The photodiode , acting as a light receiver, detects this reflected light . The sensor then processes this signal to determine the presence and potentially the distance of the obj ect , thus achieving proximity detection .

[0009] A light detection system using photodiodes can also ef fectively function as a touch sensor or touch force detector by detecting a movement of the touch screen . The sensor emits a light beam, typically infrared, towards a touch screen capable of being moved .

[0010] When a user touches the screen, the light beam is reflected back at varying intensities , depending on the force of the touch and the screen' s position . The photodiode receives this reflected light and converts it into an electrical signal . The sensor system then interprets this signal to determine not only the presence and location of a touch, but also the force applied, despite the movement of the screen . This setup is also possible without the determination of the touch force .

[0011] Touch sensors are a fundamental component in electronic devices , of fering users intuitive input methods and seamless interactions . They detect touch or pressure on a surface , which allows to navigate , type , and interact with ease .

[0012] However, as the distance between the target ( the surface being touched) and the sensor increases , the sensitivity of the sensor to target displacements decreases . This means that the sensor becomes less ef fective at detecting touch as the distance between the touch surface and the sensor increases . This is a signi ficant disadvantage as it limits the range and accuracy of the sensor .

[0013] SUMMARY

[0014] The obj ect of the present invention is therefore to provide a touch sensor device without the limitations of decreased sensitivity as the distance between the target and the sensor increases . This invention aims to maintain constant sensitivity over a larger range , enhancing the accuracy and usability of the touch sensor, even when the touch surface and the sensor are at a signi ficant distance from each other . This addresses the common issue of reduced ef fectiveness in detecting touch with increased distance , thus improving the overall performance of touch sensor technology .

[0015] According to the invention, the obj ect is met by a device speci fied in claim 1 and by a sensor arrangement , comprising a light detection system as speci fied in claim 14 and a method with the steps speci fied in claim 15 . Therefore , a light detection system is proposed by the invention, comprising :

[0016] A light detection system, comprising :

[0017] - a light emitting device configured to emit light towards a target ,

[0018] - a light detecting device , configured to detect light , positioned with a geometrical of fset from the light emitting device ,

[0019] - a substrate , having two surfaces , on one of which the light emitting device and the light detecting device are placed,

[0020] - a first panel , which extends over the substrate on the side of the substrate where the light emitting device and the light detecting device are placed, and

[0021] - a second panel , which is placed between the first panel and the substrate and extending above and at least over the light detecting device , and wherein the second panel has an aperture , which extends only partly over the light detecting device , so that a distance between a center of the aperture and the light emitting device is smaller than the distance between a center of the light detecting device and the light emitting device .

[0022] It is observed that as the distance increases , the slope of the photo-current decreases , which means the sensitivity of sensor to target displacements decreases at higher distances .

[0023] In this context , "higher sensitivity" refers to the ability of the system to detect smaller changes in the target ' s height . When the target is at a higher distance , even a small change in its height can cause a signi ficant change in the angle of the reflected light , and consequently, a noticeable change in the photo current . This means the system is very " sensitive" to changes in height at high distances .

[0024] In other words , the system ' s " sensitivity" is its ability to convert changes in the target ' s height into changes in the photo current . A "higher sensitivity" means that even small changes in height will result in signi ficant changes in the photo current .

[0025] The setup consists of a field of view limitation of the light detecting device , here an aperture , on top of a light detecting device , e . g . a photodiode , with a certain geometrical of fset such that the center of the aperture is a bit closer to the light emitting device than the center of the light detecting device .

[0026] The relative positions of aperture and light detecting device are such that as the target goes higher the reflected light from target will gradually get out of the light detecting devices ' area . Therefore , the ef fect of target height changes will be higher on the photo-current leading to a higher sensitivity at high distances , thereby enhancing the sensitivity of the device at extended ranges .

[0027] With this a simple to implement and cost-ef fective set-up with an aperture as a field of view restriction on the light detecting device , it is possible to maintain a constant level of sensitivity over a large range .

[0028] In an embodiment of the invention, the light detection system, may be a proximity detection system .

[0029] A proximity detection system is a technology that identi fies the presence or absence of obj ects in its surroundings without requiring physical contact , thus providing data on these ob ects .

[0030] Proximity detection systems work with a wide range of materials , including metal and plastic, making it suitable for use in diverse industries and applications and are reliable when working in di f ferent environments such as with high temperatures .

[0031] Moreover, when a sensing of physical contact is needed, the light detection system may be a touch sensor . In this case , the light emitting device emits light towards the surface , and the light detecting device is set to receive this light . When a finger or an obj ect comes into contact with the surface , it changes the height of the surface , which in turn alters the path of the light . The photodiode detects this change in light path, and the system interprets this as a touch event . This kind of system can provide more precise touch detection by measuring the degree of light path alteration .

[0032] In this case , the benefits of both light detection and touch sensing technologies are combined . A presence or absence of obj ects can be detected based on changes in light intensity, while also being able to sense physical contact . This dual functionality allows for more comprehensive obj ect detection and interaction providing a simple to implement and cost- ef fective system .

[0033] In a further embodiment of the invention the light detection system may be touch force detection system .

[0034] A touch force detection system, equipped with light and touch force detection capabilities , functions using a light emitting device , a light detecting device , and other force-sensing components . The light emitting device proj ects light onto a surface , and the interaction of a finger or an obj ect with the surface modi fies its height , thereby changing the light ' s traj ectory . This alteration is identi fied by the photodiode as a touch event . Furthermore , the system gauges the intensity of the touch, enabling pressure-sensitive interactions . This enhances the user experience through haptic feedback and augments functionality by di f ferentiating between various touch types based on force .

[0035] Detecting touch force on top of the touch sensor system brings several advantages . Firstly, it allows for pressure-sensitive interactions , enabling more nuanced control in applications such as digital drawing or gaming . Secondly, it can enhance user experience by providing haptic feedback, making the interaction more tactile and responsive . Lastly, it can increase the functionality of devices by distinguishing between di f ferent types of touch based on force , such as a tap versus a hard press , thereby expanding the range of possible commands or actions .

[0036] Furthermore , in the light detection system, a surface of the first panel , which is facing the light emitting device , the light detecting device and the second panel , may comprise a glossy part .

[0037] Glossy surfaces describe in this context surfaces , which have a high degree of specular reflection and minimal di f fuse reflection . This means they reflect some of the light that hits them in a single direction . For example the glossy target may reflect more than 20 % of light in a specular way and the rest ( 80 % ) in a di f fuse way .

[0038] In such a light detection system, the presence of a glossy part on the surface of the second panel , which faces the light-emitting device , can bring the benefit of a high reflectivity, which can enhance the amount of light reflected back to the light detection system, thereby improving its sensitivity and accuracy .

[0039] Furthermore , glossy surfaces tend to be more resistant to scratches and other forms of wear and tear, which could potentially increase the li fespan of the system .

[0040] In a further embodiment of the invention, the aperture may be a slit .

[0041] A slit aperture can provide more precise control over the amount of light entering the system, improving the accuracy of light detection . With this the impact of unwanted light or noise can be reduced, enhancing the system' s ability to focus on the desired light source . Furthermore , a slit aperture can enable the system to detect the directionality of light .

[0042] Moreover, the aperture may be rectangularly shaped .

[0043] A rectangular aperture of fers several advantages when it comes to light detection systems . One of the primary benefits is its ability to allow for a more uni form and controlled distribution of light . This feature enhances the accuracy of detection, making the system more reliable . Furthermore , a rectangular aperture can signi ficantly reduce the interference from unwanted light sources . This improvement leads to a better signal-to-noise ratio , which is crucial for the performance of any detection system .

[0044] In addition to these functional benefits , the rectangular shape of the aperture contributes to the versatility of the system . Its shape can be easily integrated into various designs , making it a flexible choice for di f ferent applications . Lastly, a rectangular aperture can potentially of fer better directionality in light detection, providing an additional layer of precision to the system . However the rectangular shape is not a must and the benefits discussed above may be achievable with other shapes too .

[0045] In a further embodiment , the aperture may be square shaped .

[0046] A light detection system with a square-shaped aperture brings a host of advantages . Firstly, the square aperture ensures an even light distribution, thereby increasing detection accuracy and improving the system' s overall dependability . Moreover, the square shape helps reduce interference from unwanted light sources , which in turn improves the signal-to-noise ratio , a crucial aspect of the system' s performance .

[0047] Beyond the functional advantages , the square form further boosts the system' s adaptability . Its shape allows for easy integration into diverse designs , of fering a versatile solution for multiple uses . Finally, the square opening could potentially enhance light detection directionality, introducing an additional degree of accuracy to the system . Furthermore , the edge of the aperture in the second panel may have one inclined edge on the part of the aperture which is closer to the light emitting device , and a straight edge on the part of the aperture which is further from to the light emitting device , wherein the inclined edge may be inclined so that the aperture is formed larger on the surface of the first panel facing away from the light detecting device and the aperture is formed smaller on the side opposite to this surface .

[0048] The aperture ' s inclined edge , which is closer to the lightemitting device , and a straight edge , which is further away, allow for more precise control of light entering the system, enhancing detection accuracy .

[0049] This design also minimi zes interference from unwanted light sources , improving the system' s overall performance .

[0050] Lastly, the unique design of the aperture could potentially enhance the directionality in light detection, adding an extra layer of precision to the system .

[0051] In a further embodiment , the light emitting device may comprise a light emitting diode ( LED) .

[0052] LEDs are characteri zed by their energy ef ficiency as they require less power than traditional light sources , thereby improving the energy ef ficiency of the system .

[0053] Their longevity reduces the frequency of maintenance and replacement , leading to lower costs over time .

[0054] The compact si ze of LEDs allows for a more compact system design, facilitating its use in various applications .

[0055] LEDs have the ability to switch on and of f rapidly, which enhances the responsiveness of the system . They also generate less heat compared to other light sources , reducing the risk of overheating and increasing the reliability of the system .

[0056] Moreover, the light emitting device may comprise a Vertical Cavity Surface Emitting Laser (VCSEL ) .

[0057] VCSELs are known for their high ef ficiency, converting a large portion of the input electrical power into coherent light .

[0058] This ef ficiency is coupled with low power consumption . The light emitted by VCSELs is of excellent beam quality, making them suitable for precision applications .

[0059] VCSEL devices are also capable of operating at high temperatures , up to 80 degrees Celsius . The lasing wavelength of a VCSEL is relatively stable , and the wafers are created with a cavity wavelength standard deviation of less than 2nm, ensuring wavelength uni formity and spectral width .

[0060] VCSELs are highly reliable due to their larger aperture and the PN j unction not intersecting the surface in the region of high optical intensity .

[0061] Lastly, VCSEL processing of fers cost and yield advantages as testing can be performed while the devices are still in wafer form .

[0062] In another embodiment , the light detecting device may comprise a photodiode .

[0063] Photodiodes , due to their high sensitivity to light , are highly ef fective in numerous applications where detecting light is essential . Their rapid response time allows them to swi ftly identi fy changes in light intensity, a feature that is especially useful in high-speed applications .

[0064] The signals produced by photodiodes are relatively pure and low in noise , reducing the need for additional filtering . Being solid-state devices , photodiodes of fer greater durability and are less prone to damage compared to other light detectors .

[0065] Their versatility allows them to be utili zed in a wide array of applications , ranging from basic light detection to intricate communication systems . Furthermore , the production and usage costs of photodiodes are relatively low, making them a cost-ef ficient option for many applications .

[0066] Moreover, the light detection system may comprise a chip, which is placed on the surface of the substrate on which the light emitting device is placed, and on which the light detecting device is placed .

[0067] This setup of fers a more condensed and uni fied structure , which is especially beneficial in scenarios where space is at a premium . The chip' s close location to the light emission and detection devices can boost performance by reducing signal loss and speeding up data trans fer .

[0068] The uni fication of all these elements onto a single base can simpli fy the production process , possibly resulting in cost savings .

[0069] The system' s overall robustness can also be enhanced as there are fewer individual parts that might be prone to damage . Moreover, having all components located on the same base makes maintenance and potential repairs easier to carry out .

[0070] However, the speci fic benefits can di f fer based on the precise design and application of the system .

[0071] Furthermore , the invention proposes a sensor arrangement , comprising a light detection system .

[0072] Moreover, the invention proposes a method for manufacturing a light detection system which comprises at least the steps of :

[0073] - providing a substrate having two surfaces - providing a light emitting device configured to emit light towards a target ,

[0074] - providing a light detecting device configured to detect light ,

[0075] - providing a first panel ,

[0076] - providing a second panel with an aperture ,

[0077] - placing the light emitting device on the substrate ,

[0078] - placing the light detecting device with a geometrical of fset from the light emitting device on the substrate ,

[0079] - placing the second panel above the substrate so that it extends above and at least over the light detecting device and so that the aperture extends only partly over the light detecting device , so that a center of the aperture is closer to the light emitting device and a center of the light detecting device is further to the light emitting device , and

[0080] - placing the first panel above the second panel so that the second panel is between the substrate and the first panel and so that the first panel extends over the substrate .

[0081] What has been said with respect to the device may analogously be applied to the method and therefore need not be repeated there . Method embodiments and details have a counterpart in the device and vice versa .

[0082] BRIEF DESCRIPTION OF THE DRAWINGS

[0083] In the following, the invention will be described in further detail with reference to the accompanying drawings , wherein :

[0084] FIG . 1 depicts an embodiment of the light detection system in a sectional view, and

[0085] FIG . 2 depicts an embodiment of the light detection system in a sectional view with examples of light rays , and FIG . 3 depicts the arrangement of the aperture and the light detecting device in a top view, and

[0086] FIG . 4 depicts the aperture in a sectional view, and

[0087] FIG . 5a depicts the photocurrent of two photodiodes over distance , and

[0088] FIG . 5b depicts the 60 distance resolution of two photodiodes over distance , and

[0089] FIG . 6 depicts a table showing the components for calculating the distance resolution .

[0090] Identical parts are labelled by the same reference signs .

[0091] DETAILED DESCRIPTION

[0092] In FIG . 1 an embodiment of the present invention is shown . In this embodiment , a light detection system 1 is depicted comprising a substrate 2 , a chip 4 placed on the substrate 2 , a light emitting device 8 configured to emit light towards a target and placed on the chip 4 , a light detecting device 6 configured to detect light and placed on the chip 4 and positioned with a geometrical of fset from the light emitting device 8 .

[0093] In this configuration, the light detection system 1 further comprises a first panel 10 extending over the substrate 2 and a second panel 12 , which is placed between the first panel 10 and the substrate 2 and extends above and at least over the light detecting device 6 .

[0094] The second panel 12 has an aperture 14 , which extends only partly over the light detecting device 6 , so that a distance between a center of the aperture 14 and the light emitting device 8 is smaller than a distance between a center of the light detecting device 6 and the light emitting device 8 . In this context the light detection system 1 can be a proximity detection system and / or a touch sensor and / or a touch force detection system.

[0095] In this scenario, an optical proximity detector is used as an example of a light detection system, serving as an alternative to capacitive sensors for detecting force touch. The proximity sensor including a touch sensor with a touch force detection system measures the diffused or directly reflected light from a surface.

[0096] When the surface is touched externally, for instance, the distance to the sensor changes, and this change in reflected light is associated with the force of touch. As the gap between the target and the sensor increases, the sensor's sensitivity to changes in the target's position decreases. However, this invention introduces a method to maintain consistent sensitivity over a larger range.

[0097] It has been observed that as the distance increases, the slope of the detected photocurrent decreases, indicating that the sensor's sensitivity to changes in the target's position decreases at greater distances. This invention suggests a method to prevent this decrease in sensitivity at greater distances .

[0098] In this context, "higher sensitivity" refers to the system's ability to detect minor changes in the target's height. When the target is at a greater distance, even a small change in its height can cause a significant change in the angle of the reflected light, and consequently, a noticeable change in the photocurrent. This implies that the system is highly "sensitive" to changes in height at greater distances.

[0099] In other words, the system's "sensitivity" is its ability to translate changes in the target's height into changes in the photocurrent. A "higher sensitivity" implies that even minor changes in height will result in significant changes in the photocurrent .

[0100] The setup includes a field of view limitation of the light detecting device 6, in this case, an aperture 14, placed on top of the light detecting device 6, such as a photodiode, with a certain geometric offset so that the center of the slit is slightly closer to the light emitting device 8 than the center of the light detecting device 6.

[0101] The relative positions of the aperture 14 and the photodiode 6 are such that as the target rises, the reflected light from the target will gradually move out of the photodiode 6 area, as it can be seen in FIG. 2 and FIG. 3. Therefore, changes in the target's height will have a greater impact on the photocurrent, leading to higher sensitivity at greater distances, thereby improving the device's sensitivity at extended ranges.

[0102] With this simple and cost-effective setup with an aperture 14, it is possible to maintain a constant level of sensitivity over a large range.

[0103] A surface 16 of the second panel 10 which is facing the light emitting device 8 comprises a glossy part. This can bring the benefit of a high reflectivity, which can enhance the amount of light reflected back to the light detection system 1, thereby improving its sensitivity and accuracy.

[0104] Furthermore, the light emitting device 8 can comprise a LED (light emitting diode) or a VCSEL (vertical cavity surface emitting laser) and the light detecting device 6 can comprise a photodiode.

[0105] The light detection system 1 might be comprised in a sensor arrangement .

[0106] Furthermore, the aperture 14 might be a slit, which can be rectangularly or square shaped. As it can be seen from FIG . 4 the edge of the aperture 14 in the second panel has one inclined edge 18 on the part of the aperture which is closer to the light emitting device 8 , and a straight edge 20 on the part of the aperture which is further from to the light emitting device 8 , wherein the inclined edge 18 is inclined so that the aperture 14 is formed larger on the surface of the first panel 10 facing away from the light detecting device 6 and the aperture 14 is formed smaller on the side opposite side to this surface .

[0107] With this further field of view limitation, the ef fect of directing the light beams is furthermore enhanced .

[0108] As it can be seen from FIG . 2 , light beams 22 , 24 from the light emitting device 8 hit the surface 16 of the first panel 10 , are reflected of f the glossy surface and are traveling from there to the light detecting device 6 .

[0109] The first panel ( 10 ) might be moved by, e . g . a touch from a user . So , when it is nearer to the light detecting device 6 , the light beams 22 reflect of f the surface 16 , where the angle of incidence equals the angle of reflection . They are hitting the light detecting device 6 .

[0110] Whereas the light beams 24 reflect of f the surface 16 , which has moved further away from the light detecting device 6 and hit the light detecting device 6 due to the field of view restriction, here the aperture 14 , only partly .

[0111] This can also be seen from FIG . 3 : the area 28 is the area where the light beams 22 reflected of f the surface 16 are hitting the photo diode 6 and the area 26 is the area where the light beams 24 reflected of f the surface 16 are hitting the photo diode 6 . The area 28 is fully on the area of the light detecting device 6 , whereas parts of the area 26 are beside the area of the light detecting device 6 . Therefore, as the target ascends, the reflected light will progressively exit the area of photodiode 6. Consequently, alterations in the target's elevation will exert a more pronounced effect on the photocurrent. This results in heightened sensitivity at increased distances, thereby enhancing the device's sensitivity across broader ranges.

[0112] FIG. 5a und 5b are displaying a behavior of a photodiode without field of view restriction (graph 30, 34) and of a photodiode with field of view restriction (graph 32, 36) as described above (aperture 14) .

[0113] In FIG. 5a the photocurrent of those photodiodes is depicted over the distance (x-axis) .

[0114] In FIG. 5b 6o distance resolution is depicted over the distance (x-axis) .

[0115] In FIG. 5a, the photocurrents 30, 32 of two photodiodes are depicted over the distance (on the x-axis) . Graph 32 exhibits a steeper slope at greater distances. The minimum detectable change in distance, also known as the 6-sigma distance resolution, at a given Signal-to-Noise Ratio (SNR) can be derived from this figure. It is calculated as 6 divided by the product of SNR and the normalized slope of the photocurrent versus distance curve.

[0116] The 6-sigma distance resolution is displayed in FIG. 5b at an SNR of 70dB.

[0117] As the distance increases, the distance resolution of graph 34 also increases, which is a common characteristic of touch sensors. However, the distance resolution for graph 36 remains constant, showcasing the advantage of this invention.

[0118] It is important to note that the minor fluctuations observed in the plot are attributable to the resolution of the simulation. This means that the small variations in the plot are due to the granularity of the simulation, not the performance of the sensors . This invention provides a consistent distance resolution, which is a signi ficant advantage in applications requiring precise measurements .

[0119] The distance resolution can be calculated by with the following :

[0120] A / 61 h>SNR Ah as it can be seen from FIG . 6 .

[0121] The distance resolution operates independently of the light detecting device 6 area and the LED current . This means that variations in the light detecting device 6 area or the LED current do not influence the value of the distance resolution .

[0122] Despite this independence , the light detecting device 6 area and LED current are not insigni ficant . They are crucial in maintaining a speci fic Signal-to-Noise Ratio ( SNR) . The SNR is a critical measure in communication systems , including this context involving LED signals , as it compares the strength of the desired signal against the background noise .

[0123] The method for manufacturing such a light detection system 1 involves firstly the provision of the substrate 2 having two surfaces that serves as the foundation for the system .

[0124] Next , two devices are provided : a light emitting device 8 and a light detecting device 6 . The light emitting device 8 is speci fically configured to emit light towards a target , while the light detecting device 6 is designed to detect this light In addition to these components , two panels 10 , 12 are provided . The first panel 10 is a standard one , while the second panel 12 is designed with an aperture 14 .

[0125] The assembly process then begins with the placement of the light emitting device 8 on the substrate 2 . The light detecting device 6 is also placed on the substrate 2 , but it is positioned with a geometrical of fset from the light emitting device 8 .

[0126] The second panel 12 is then positioned above the substrate 2 . It is arranged in such a way that it extends above and at least over the light detecting device 6 . The aperture 14 in the second panel is aligned so that it only partly covers the light detecting device 6 . This alignment ensures that the center of the aperture 14 is closer to the light emitting device 8 , while the center of the light detecting device 6 is further away from the light emitting device 8 .

[0127] The final step in the assembly process involves placing the first panel 10 above the second panel 12 . This arrangement ensures that the second panel 12 is sandwiched between the substrate 2 and the first panel 10 , and that the first panel 10 extends over the substrate 2 .

[0128] The steps described need not to be in a certain order . Some can be done before others , or vice versa, depending on the needs of the application .

[0129] List of abbreviations : LIST OF REFERENCE SIGNS

[0130] Light detection system 1

[0131] Substrate 2

[0132] Chip 4

[0133] Light detecting device 6

[0134] Light emitting device 8

[0135] First panel 10

[0136] Second panel 12

[0137] Aperture 14

[0138] Surface 16

[0139] Edge 18

[0140] Edge 20

[0141] Light beam 22

[0142] Light beam 24

[0143] Area 26

[0144] Area 28

[0145] Graph 30

[0146] Graph 32

[0147] Graph 34

[0148] Graph 36

Claims

CLAIMS1. A light detection system (1) , comprising:- a light emitting device (8) configured to emit light towards a target,- a light detecting device (6) , configured to detect light, positioned with a geometrical offset from the light emitting device (8) ,- a substrate (2) , having two surfaces, on one of which the light emitting device (8) and the light detecting device (6) are placed,- a first panel (10) , which extends over the substrate (2) on the side of the substrate (2) where the light emitting device (8) and the light detecting device (6) are placed, and- a second panel (12) , which is placed between the first panel (10) and the substrate (2) and extending above and at least over the light detecting device( 6 ) , and wherein the second panel (12) has an aperture (14, which extends only partly over the light detecting device (6) , so that a distance between a center of the aperture (14) and the light emitting device (8) is smaller than the distance between a center of the light detecting device (6) and the light emitting device (8) .

2. A light detection system (1) according to claim 1, wherein the light detection system (1) is a proximity detection system.

3. A light detection system (1) according to claim 1, wherein the light detection system (1) is a touch sensor.

4. A light detection system (1) according to claim 1, wherein the light detection system (1) is a touch force detection system.

5. A light detection system (1) according to any one of the preceding claims, wherein a surface (16) of the first panel (10) , which is facing the light emitting device (8) , the light detecting device (6) and the second panel (12) , comprises a glossy part .

6. A light detection system (1) according to any one of the preceding claims, wherein the aperture (14) is a slit.

7. A light detection system (1) according to any one of the preceding claims, wherein the aperture (14) is rectangularly shaped.

8. A light detection system according (1) to any one of claims 1 to 6, wherein the aperture (14) is square shaped.

9. A light detection system (1) according to any one of the preceding claims, wherein the edge of the aperture (14) in the second panel(12) has one inclined edge (18) on the part of the aperture (14) which is closer to the light emitting device (8) , and a straight edge (20) on the part of the aperture (14) which is further from to the light emitting device (8) , wherein the inclined edge (18) is inclined so that the aperture (14) is formed larger on the surface of the first panel (10) facing away from the light detecting device (6) and the aperture (14) is formed smaller on the side opposite to this surface.

10. A light detection system (1) according to any one of the preceding claims, wherein the light emitting device (8) comprises a light emitting diode (LED) .

11. A light detection system (1) according to any one of claims 1 to 9, wherein the light emitting device (8) comprises a Vertical Cavity Surface Emitting Laser (VCSEL) .

12. A light detection system (1) according to any one of the preceding claims, wherein the light detecting device (6) comprises a photodiode .

13. A light detection system (1) according to any one of the preceding claims, comprising a chip (4) , which is placed on the surface of the substrate (2) on which the light emitting device (8) is placed, and on which the light detecting device (6) is placed.

14. A sensor arrangement, comprising a light detection system(1) according to any one of the preceding claims.

15. Method for manufacturing a light detection system (1) according to any one of claims 1 to 13, comprising the following steps:- providing a substrate (2) having two surfaces,- providing a light emitting device (8) configured to emit light towards a target,- providing a light detecting device (6) configured to detect light,- providing a first panel (10) ,- providing a second panel (12) with an aperture (14) ,- placing the light emitting device (8) on the substrate ( 2 ) ,- placing the light detecting device (6) with a geometrical offset from the light emitting device (8) on the substrate (2) ,- placing the second panel (12) above the substrate (2) so that it extends above and at least over the light detecting device (6) and so that the aperture (14) extends only partly over the light detecting device(6) , so that a center of the aperture (14) is closer to the light emitting device (8) and a center of the light detecting device (6) is further to the light emitting device (8) , and placing the first panel (10) above the second panel (12) so that the second panel (12) is between the substrate (2) and the first panel (10) and so that the first panel (10) extends over the substrate (2) .

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