Driver monitoring system for vehicles

Abstract

This disclosure relates to a driver monitoring system (2) for a vehicle (1), comprising: - a camera (3) configured to capture infrared light, - an infrared illumination unit (4) configured to illuminate a driver, particularly the driver's face, with infrared light, and - a surface (5) positioned in an optical path between the camera (3) and the driver (D), wherein the surface (5) a) is at least reflective in the infrared spectrum, or b) comprises a coating (6) having at least one layer (7) that is at least reflective in the infrared spectrum, wherein the surface (5) is arranged such that infrared light generated by the infrared illumination unit (4) is reflected from the driver's face to the camera (3), such that the camera (3) captures the driver's face.

Description

[0001] This invention relates to a driver monitoring system for vehicles. Furthermore, this invention relates to vehicles including such a driver monitoring system.

[0002] Driver monitoring systems utilizing infrared detectors (such as cameras) are commonly installed in modern vehicles to analyze the driver's face and detect signs of fatigue or inattention. These cameras are typically mounted on or near the dashboard, usually close to the driver information display or even integrated into the same housing. For example, in some cars, the camera is positioned close to the display. These systems may use infrared light, invisible to the human eye, to capture the driver's facial features. A drawback of existing driver monitoring systems is that the camera must always maintain an unobstructed line of sight with the driver. This presents a challenge in concealing the camera outside the driver's field of vision while ensuring reliable operation. In some cases, the camera is very conspicuous, such as when mounted alone in front of the display. In other configurations, the camera is hidden behind a dark area of ​​the display housing, which can affect image quality and system efficiency. Furthermore, integrating the camera into the display unit can lead to heat dissipation issues, as the camera system may increase the heat load on the display components.

[0003] The objective of this disclosure is to provide a driver monitoring system for vehicles that provides the driver with a direct view while improving the concealment of the camera and related system components.

[0004] This objective is achieved through the driver monitoring system for vehicles disclosed herein and the vehicle disclosed herein. Preferred or advantageous embodiments can be deduced from the specification and drawings.

[0005] According to a first aspect of the invention, a driver monitoring system for a vehicle includes: a camera configured to capture infrared light; an infrared illumination unit configured to illuminate a driver, particularly the driver's face, with the infrared light; and a surface positioned in an optical path between the camera and the driver. The surface is at least reflective in the infrared spectrum, or comprises a coating having at least one layer that is at least reflective in the infrared spectrum. The surface is arranged such that infrared light emitted by the infrared illumination unit can be reflected from the driver's face to the camera, thereby allowing the camera to capture the driver's face. By utilizing infrared light, the system remains fully functional even in low-light or nighttime conditions, thereby ensuring continuous monitoring of the driver's state.

[0006] In one embodiment, the surface is part of a separate component that is at least reflective in the infrared spectrum. In another embodiment, a coating is applied to the surface, wherein the coating with a reflective layer is at least reflective in the infrared spectrum. In the latter case, the separate component may be non-reflective in the visible spectrum. This allows for greater flexibility in the selection of materials and designs for reflective components or reflective coatings, enabling seamless integration into different vehicle interiors. A coating is a thin layer of material applied to the surface of an object to alter its optical properties. A coating may have one or more layers.

[0007] The camera is an infrared camera and is part of a system that analyzes the driver's face to detect fatigue or inattention. The camera is positioned such that it captures the driver's face by reflecting infrared light from a reflective component or coated surface. The surface acts as a mirror for the camera, and any surface within the vehicle that is at least reflective in the infrared spectrum or coated with an infrared-reflective layer can serve this purpose. The surface can be flat or have a large radius of curvature; the smaller the radius of curvature, the greater the perceived width of the face in the reflection. The surface is mounted at a predetermined angle relative to the driver and the camera to optimize the reflection of the driver's image toward the camera. This configuration ensures that the driver cannot see the camera. Therefore, vehicle manufacturers can maintain a clean and aesthetically pleasing cockpit design while still incorporating an effective driver monitoring system.

[0008] The term "infrared light" refers to "light in the infrared spectrum." Both terms refer to electromagnetic radiation in the infrared (IR) wavelength range, which ranges from approximately 700 nanometers (nm) to 1 millimeter (mm). By limiting the system to this spectral range, interference from visible light sources such as dashboard lighting or other vehicle lighting can be minimized, thereby further improving the accuracy of facial recognition.

[0009] In a preferred embodiment, at least one layer is non-reflective in the visible spectrum. This ensures that reflective properties do not interfere with the driver's vision or cause harmful glare. This is particularly beneficial when the surface is a display screen, as it prevents interfering reflections that could impair readability.

[0010] The surface can be made of glass, plastic, or any other material on which at least one layer can be applied. Where the surface has infrared reflective properties, it should be particularly suitable for high reflectivity in the infrared spectral range. Furthermore, the coating can be designed to withstand environmental factors such as temperature fluctuations and ultraviolet radiation, ensuring long-term stability and performance.

[0011] Preferably, the infrared illumination unit is positioned at a certain spatial distance from the camera. In other words, the infrared illumination unit can be positioned independently of the camera, allowing for flexible layout within the vehicle. The camera and infrared illumination unit can be distributed in different mounting locations within the vehicle, enabling flexible integration into various vehicle designs. This independent arrangement also prevents harmful reflections from interfering with the captured image and allows for optimized illumination of the driver's face, regardless of seat position or height. Alternatively, the infrared illumination unit and camera can be arranged adjacent to each other. Furthermore, the infrared illumination unit and camera can form a single unit.

[0012] A camera can be connected to an evaluation unit that processes the captured images to monitor the driver's attention. The evaluation unit can be a separate unit of the system. Alternatively, the evaluation unit can be part of the vehicle control system. In the former case, the evaluation unit can be connected to the vehicle control system via signal transmission.

[0013] The camera may include a heating element to prevent condensation or fogging on the lens. This feature is particularly advantageous in cold or humid environments, ensuring continuous operation even in harsh weather conditions.

[0014] The surface coating (including at least one layer that is at least reflective in the infrared spectrum) may include at least one anti-reflective layer. The anti-reflective coating increases the reflectivity of the camera while improving driver readability. The performance of the anti-reflective coating is improved by adding additional layers; the anti-reflective layer can be specifically modified to have higher reflectivity in the infrared range. Upon customer request, the anti-reflective layer can be applied to the front glass of the display. Additional infrared reflective layers can also be combined to enhance performance. In one embodiment, several anti-reflective layers can be applied to a surface or an existing coating to form an anti-reflective coating that reduces harmful reflections in a specific wavelength range while optimizing reflective characteristics. For example, the coating consists of four layers: a first layer is niobium pentoxide (Nb₂O₅) applied to the surface, which can be made from a glass substrate; a second layer is silicon dioxide (SiO₂); a third layer is Nb₂O₅; and a fourth layer is SiO₂. This layer structure is designed to enhance reflectivity in the infrared spectrum while minimizing reflections in the visible spectrum, thereby ensuring that the camera can effectively reflect infrared light while maintaining a clear view for the driver.

[0015] In another embodiment, the coating includes at least one anti-glare layer. In one embodiment, an anti-glare layer may be applied to a surface or an existing coating to form an anti-glare coating. These layers reduce glare by reducing specular reflection and enhancing light diffusion. The anti-glare layer or coating may be applied using different techniques, such as spraying or etching. In spraying methods, small particles are deposited on the surface, producing surface scattering or volume scattering, thereby diffusing incident light. In etching processes, material is selectively removed from the surface, modifying its microstructure to achieve a similar glare reduction effect.

[0016] Layers that are reflective in the infrared spectrum can have matte or glossy surface finishes, with their reflective properties optimized based on the finish. In this context, "matte" refers to a surface finish that diffuses light, thereby reducing glare and harmful reflections. "Glossy" refers to a smooth, highly reflective surface that enhances infrared reflection from the camera but may require anti-glare treatment to prevent visible reflections. Anti-glare coatings can be advantageously used in displays. The choice between matte and glossy surface finishes depends on specific integration requirements and user preferences to ensure high-quality image capture.

[0017] Additional layers (such as an anti-glare layer on top of an infrared reflective layer) can be used to improve visual comfort, but they are not essential to the core functionality of the system.

[0018] To protect the camera, it is preferably covered by a cover that allows at least infrared light to pass through. This cover is preferably made of glass or plastic that is transparent only in the infrared spectrum. This ensures minimal visible light interference while maintaining the system's ability to operate effectively.

[0019] According to a second aspect of the invention, a vehicle includes a driver monitoring system according to the first aspect of the invention. The vehicle can be a passenger car, commercial vehicle, truck, motorcycle, aircraft, etc. This invention is particularly advantageous for automated or semi-automated driving systems that require continuous monitoring of the driver for safety reasons.

[0020] Preferably, the camera is located outside the driver's line of sight during vehicle use. In one embodiment, the camera is positioned within the housing of the vehicle's steering wheel, in the vehicle's headliner, or within the dashboard, for example, in an opaque frame section facing the windshield. In each case, the camera is pointed towards a reflective surface to capture the driver's face through reflection. These configurations allow for flexible integration while concealing the camera from the driver's line of sight. Other layouts of the camera within the vehicle are also possible depending on the integration of the display. By cleverly placing the camera, interference with other vehicle functions, such as head-up displays or rearview mirror systems, can be avoided.

[0021] A preferred embodiment of the vehicle includes a display, wherein the front surface of the display is coated with at least one infrared reflective layer. The camera is invisible to the driver, allowing the use of standard display panels such as LCD and OLED. Furthermore, the camera's heat does not affect the display, and the heat absorbed by the components is reduced because the camera reflects external heat (e.g., sunlight). This configuration improves system efficiency while maintaining optimal performance during extended vehicle operation.

[0022] Alternatively, the windshield can act as a reflective surface by applying an infrared-reflective coating to either the inner or outer surface of the windshield. If applied to the outer surface, the windshield at least allows infrared light to pass through.

[0023] Furthermore, the infrared illumination unit can be integrated into the vehicle's steering wheel housing or dashboard. The illumination unit does not need to be positioned close to the camera; instead, it can be flexibly arranged within the cockpit, such as in displays, the steering wheel, or other interior components.

[0024] Preferably, the windshield has a device for protecting the camera from indirect exposure to sunlight, particularly when the camera is oriented in a substantially vertical direction. This protection is achieved by integrating an infrared filter or sunshade element into the opaque frame section of the windshield, preventing excessive sunlight from interfering with the capture of infrared images. By reducing harmful infrared radiation from external light sources, image quality is improved, thus ensuring more reliable driver monitoring. Furthermore, this design minimizes the risk of sensor overheating, thereby improving the overall durability and performance of the camera. Another advantage is that image contrast remains stable even under varying sunlight conditions, allowing for more accurate detection of facial features.

[0025] Compared to traditional driver monitoring systems, this invention offers several key advantages. Since the camera does not need to maintain direct line of sight with the driver, it can be concealed more effectively. The display size is not limited by the camera's placement, allowing for greater design flexibility. The separation of the camera and lighting unit further reduces the thermal impact on the display. The system requires less power compared to solutions where the camera is integrated into or behind the display, as display transmission losses are minimized. This system is beneficial not only for passenger vehicles but also for public transportation systems requiring driver monitoring. It is also beneficial in other fields requiring the capture and analysis of people, particularly faces or facial features.

[0026] Further details are explained with reference to the additional figures below. These are shown in: Figure 1 A longitudinal sectional view of the driver's cabin of the vehicle according to the first embodiment is used to illustrate the structure of the driver monitoring system. Figure 2A longitudinal sectional view of the cockpit according to the second embodiment is used to illustrate the structure of the driver monitoring system. Figure 3 A longitudinal sectional view of the cockpit according to the third embodiment is used to illustrate the structure of the driver monitoring system, and Figure 4 A longitudinal sectional view of the cockpit according to the fourth embodiment is used to illustrate the structure of the driver monitoring system.

[0027] Figures 1 to 4 Different embodiments of the driver monitoring system 2 integrated into vehicle 1 according to the present invention are shown. Figures 1 to 4 Each shows a longitudinal sectional view of the cockpit of the exemplary vehicle 1.

[0028] The driver monitoring system 2 includes: an infrared camera 3 configured to capture infrared light; an infrared illumination unit 4 configured to illuminate the driver D, particularly the driver's face; and a surface 5 positioned in the optical path between the camera 3 and the driver D. The surface 5, which reflects infrared light, is positioned at a predetermined angle relative to the driver D to optimize the reflection of the driver's image toward the camera 3. This arrangement ensures that the camera 3 can capture a high-contrast image of the driver D even under varying lighting conditions inside the vehicle.

[0029] according to Figure 1 Surface 5 is the front surface of display 15 of vehicle 1, arranged at an angle such that surface 5 acts as a mirror for camera 3. Display 15 is integrated into dashboard 16. Surface 5 of display 15 includes a coating 6 having at least one layer 7, wherein layer 7 is at least reflective in the infrared spectrum. Layer 7 may be an anti-reflective layer. Surface 5 is oriented such that infrared light is reflected downwards onto camera 3, which is oriented vertically upwards. This positioning allows camera 3 to be mounted covertly while still capturing unobstructed reflections of the driver's face. Camera 3 and infrared illumination unit 4 are connected to evaluation unit 8 via signal transmission, wherein evaluation unit 8 can receive signals from camera 3 and evaluate the data based on the driver's attention state. Figure 1 In this example, evaluation unit 8 is shown only as an example and is highly illustrative.

[0030] Infrared illumination unit 4 emits infrared light, which is reflected back to surface 5 from the driver's face. Camera 3 captures the driver's face via the infrared light reflected from surface 5, thereby ensuring reliable face detection. In this embodiment, surface 5 is part of display 15 coated with infrared reflective layer 7. Camera 3 and infrared illumination unit 4 are each disposed within housing 10 of steering wheel 11 and are spaced apart from each other, with camera 3 covered by cover 9 that at least allows infrared light to pass through. In this embodiment, camera 3 is also protected from at least indirect sunlight. This configuration further ensures that the infrared illumination does not produce harmful glare or reflections on other surfaces within the vehicle, thereby improving the accuracy of monitoring system 2.

[0031] exist Figure 2 The diagram illustrates an alternative implementation of the driver monitoring system 2. The camera 3 is integrated into the housing 10 of the steering wheel 11, while surface 5 is again part of the display 15 coated with an infrared reflective layer 7. This layer 7 may be an anti-reflective layer. The infrared illumination unit 4 is separately positioned within the instrument panel 16, ensuring flexible integration into the cockpit design. This arrangement of the camera 3 and the infrared illumination unit 4 ensures that they are always outside the driver's direct line of sight. By positioning the camera 3 within the steering wheel housing 10, system 2 can utilize a stable and vibration-free mounting position, which helps maintain image clarity even when the vehicle is in motion.

[0032] Figure 3 A third embodiment is shown, in which camera 3 and infrared illumination unit 4 are arranged within the roof liner 12 of vehicle 1. Infrared illumination unit 4 is placed independently of camera 3. This configuration further enhances the ability to conceal camera 3 and infrared illumination unit 4 while maintaining effective driver monitoring functionality. In this embodiment, a separate component 18 is arranged at the dashboard, and component 18 is at least reflective in the infrared spectrum. This is to illustrate that displays, particularly the surface of displays, do not necessarily have to be used to reflect infrared light. Other parts and / or components within vehicle 1 can be used to reflect the infrared light illuminating driver D back to camera 3, provided that the part or component is at least reflective in the infrared spectrum. Alternatively, the surface of the part or component can be coated with a coating having at least one layer, said coating being at least reflective in the infrared spectrum, similar to... Figure 1 and Figure 2 In this embodiment, camera 3 is well protected from sunlight. Furthermore, this configuration allows for greater design flexibility, as the reflective element 18 can be strategically placed to optimize the reflection path of camera 3, even within different vehicle interiors.

[0033] Figure 4A fourth embodiment is shown, in which camera 3 is integrated into the dashboard 16 and vertically upward along the windshield 14 of vehicle 1. Figure 1 and Figure 2 Similarly, the inner surface 5 of the windshield 14 is coated with a coating 6, which comprises two layers: a first layer 7 in the form of an anti-reflective layer and a second layer 17 in the form of an anti-glare layer. In this embodiment, the infrared illumination unit 4 is arranged in the area of ​​the display. By integrating the infrared reflective surface 5 into the windshield 14, the system minimizes the number of additional components required for implementation, thereby reducing manufacturing costs and simplifying assembly.

[0034] In all embodiments, surface 5 acts as an infrared reflector for camera 3, thus allowing detection of driver D's face without a direct line of sight between the camera and driver D. By using infrared reflective surface 5 and / or an infrared reflective layer 7 of coating 6 (which is also non-reflective in the visible spectrum), system 2 ensures that reflections do not interfere with the driver's line of sight. The flexible layout of camera 3 and infrared illumination unit 4 allows the use of standard display panels such as LCD or OLED while minimizing the thermal impact on display components. Furthermore, the ability to utilize different surfaces within vehicle 1 as infrared reflectors enhances the adaptability of system 2, making it suitable for various vehicle designs and interior layouts.

[0035] It should be understood that the present invention is not limited to the exemplary embodiments shown and described herein. Rather, other embodiments will be apparent to those skilled in the art from the overall context of the foregoing explanation. In particular, the embodiments described herein can be effectively combined.

[0036] Figure Labels

Claims

1. A driver monitoring system (2) for a vehicle (1), comprising: - Camera (3), which is configured to capture infrared light, - Infrared illumination unit (4), the infrared illumination unit being configured to illuminate the driver, particularly the driver's face, with infrared light, and - Surface (5), said surface being positioned in the optical path between said camera (3) and said driver (D), wherein said surface (5) a) It has at least reflectivity in the infrared spectrum, or b) Includes a coating (6) having at least one layer (7) that is at least reflective in the infrared spectrum. The surface (5) is arranged such that infrared light generated by the infrared illumination unit (4) is reflected from the driver’s face to the camera (3), so that the camera (3) captures the driver’s face.

2. Driver monitoring system (2) according to claim 1, characterized in that The at least one layer (7) is non-reflective in the visible spectrum range of the human eye.

3. Driver monitoring system (2) according to claim 1 or 2, characterized in that The infrared illumination unit (4) is arranged at a certain spatial distance from the camera (3).

4. Driver monitoring system (2) according to any one of the preceding claims, characterized in that The camera (3) is connected to the evaluation unit (8).

5. Driver monitoring system (2) according to any one of the preceding claims, characterized in that The coating (6) includes at least one anti-reflective layer.

6. The driver monitoring system (2) according to any one of the preceding claims, characterized in that, The coating (6) includes at least one anti-glare layer.

7. Driver monitoring system (2) according to one of the preceding claims, characterized in that The camera (3) is covered by a cover (9) that allows at least infrared light to pass through.

8. A vehicle (1) comprising a driver monitoring system (2) according to any one of the preceding claims.

9. The vehicle (1) according to claim 8, characterized in that During vehicle use, the camera (3) is located outside the driver's line of sight.

10. The vehicle (1) according to claim 8 or 9, characterized in that The camera (3) is arranged inside the housing (10) of the steering wheel (11).

11. The vehicle (1) according to claim 8 or 9, characterized in that The camera (3) is positioned in the roof lining (12) of the vehicle (1).

12. The vehicle (1) according to any one of claims 8 to 11, further comprising a display (15), wherein the front surface (5) of the display (15) is coated with the at least one layer (7).

13. The vehicle (1) according to any one of claims 8 to 11, characterized in that, The surface (5) of the windshield (14) is coated with at least one layer (7).

14. The vehicle (1) according to any one of claims 8 to 13, characterized in that The infrared illumination unit (4) is integrated into the housing (10) or instrument panel (16) of the steering wheel (11).

15. The vehicle (1) according to any one of claims 8 to 14, characterized in that The windshield (14) has a device for protecting the camera (3) from at least indirect exposure to sunlight.

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