Reflector design for DMS cameras

Abstract

The invention relates to reflectors of OMS (Occupant Monitoring Systems) and DMS (Driver Monitoring Systems) cameras used in automotive safety and in-vehicle monitoring systems to track driver attention and prevent accidents.

Description

[0001] REFLECTOR DESIGN FOR DMS CAMERAS

[0002] Technical Field

[0003] The invention relates to reflectors of OMS (Occupant Monitoring Systems) and DMS (Driver Monitoring Systems) cameras used in automotive safety and in-vehicle monitoring systems to track driver attention and prevent accidents.

[0004] Background Art

[0005] Driver monitoring systems utilize various devices such as in-vehicle sensors and cameras to monitor the driver's level of attention, fatigue, and other behaviours. These systems play a critical role in enhancing driver safety, preventing accidents, and optimizing driving performance. Current DMS and OMS technologies typically use infrared illumination to monitor and analyse driver behaviours. Infrared illumination is ideal for detecting facial expressions, eye movements, and head positions of the driver under low-light conditions or during night driving. Since infrared light is invisible, it does not disturb the driver and does not affect their natural behaviour.

[0006] Reflectors ensure that the infrared light is reflected toward the driver's face, allowing the camera system to collect clear and accurate data. Existing reflector technologies are generally made of materials that provide high reflectance efficiency and are designed to reflect light at a specific angle. Depending on their surface structure, reflectors can reflect light at different angles, directly affecting the performance of the detection system. If reflectors are not properly designed, unwanted reflections may occur. These reflections can prevent the camera from collecting accurate data and lead to incorrect detections. Stray light usually results from a non-smooth reflective surface or incorrect placement angles. If reflectors are not sufficiently isolated, lighting homogeneity may be disrupted. Light leakage, which occurs when light escapes from the edges or attachment points of the reflector, can compromise detection accuracy.

[0007] Infrared filter glasses are generally used in two parts. This design reduces the problem of stray light by blocking light reflected from inside the IR filter. However, proper alignment and assembly of these structures have critical importance TIR (Total Internal Reflection) lenses placed in front of IR illumination LEDs direct the light at a specific angle. TIR lenses increase lighting efficiency and minimize unwanted light dispersion. However, the positioning and surface quality of TIR. lenses directly affect system performance. The use of I filter glasses and TIR lenses in such ways are important steps aimed at improving the efficiency and accuracy of systems.

[0008] In current DMS and OMS technologies, the reflectors are used in conjunction with infrared (IR) illumination to accurately detect the driver's facial expressions and eye movements. However, technical issues such as stray light and light leakage limit the performance of these systems.

[0009] The flat inner surfaces of the reflectors used in DMS and OMS technologies allow light to enter directly from the IR filter into the camera lens. This direct light causes light rings and glare in the image, making it difficult to detect the driver. Moreover, if the intensity of this light is too high, it may lead to a complete failure in detecting the driver. Such technical problems, including stray light and light leakage, negatively affect the overall performance of DMS and OMS systems.

[0010] US Patent No. US11117515 details reflector-based infrared illumination systems used in in-vehicle monitoring systems. The system includes reflector structures that enable the effective reflection of infrared light toward the driver's face. However, due to problems of stray light and light leakage, the detection accuracy is limited. International patent application WO 2018 / 039278 describes the design of multilayer reflectors used in DMS and OMS systems. The reflectors are optimized to provide high reflectance efficiency at different angles. Nevertheless, issues with light leakage have been observed under various driving conditions. The IEEE Transactions on Intelligent Transportation Systems article discusses research conducted to improve the optical performance of reflectors used in DMS and OMS systems. The study examines how problems such as stray light and light leakage can be minimized through improvements in reflector materials and designs. A white paper published by Visteon details how using IR filter glasses in two parts minimizes infrared light reflection and how TIR lenses increase the efficiency of IR illumination. These solutions are considered important steps for improving the performance and reliability of DMS and OMS systems. Purpose of the Invention

[0011] This invention aims to prevent image distortions and light rings caused by light entering directly from the IR filter into the camera lens, and to enhance the reliability, performance, and cost-effectiveness of reflector technologies used in driver monitoring systems (DMS and OMS).

[0012] Detailed Description of the Invention

[0013] The subject of the invention is illustrated in the attached figures of the reflector.

[0014] Figure 1 - View of reflector parts

[0015] Figure 2 - Sectional views of reflector parts

[0016] Figure 3 - Path followed by light inside the reflector

[0017] Figure 4 - External view of the reflector

[0018] The parts in the above figures are numbered as follows:

[0019] 1. IR Filter

[0020] 2. IR LED

[0021] 3. IR LED Housing

[0022] 4. Inner Surface of IR LED Housing Reflector

[0023] 4.1. First Surface

[0024] 4.1.1. First Step

[0025] 4.1.2. Second Step

[0026] 4.2. Second Surface

[0027] 4.2.1. Third Step

[0028] 4.2.2. Fourth Step

[0029] 5. Cooling Slot

[0030] 6. Camera

[0031] 7. Housing

[0032] 8. Back Cover

[0033] 9. Camera Housing

[0034] A. Second Step Width

[0035] B. Fourth Step Width

[0036] C. First Step Height

[0037] D. Second Step Height

[0038] E. Fourth Step Height F. Third Step Height

[0039] G. First Angle

[0040] H. Second Angle

[0041] I. First Base Angle

[0042] J. Second Base Angle

[0043] The invention is a reflector for DMS and QMS cameras, comprising at least one IR LED (2) located within the Housing (7), the IR. LED (2) being placed inside the IR LED Housing (3), and the IR LED Housing (3) comprising the Inner Surface of IR LED Housing Reflector (4); characterized in that the Inner Surface of IR LED Housing Reflector (4) includes on its side wall a First Surface (4.1) comprising a First Step (4.1.1) and a Second Step (4.1.2) formed to create a First Angle (G) between them; and on the wall of the Camera Housing (9), a Second Surface (4.2) comprising a Third Step (4.2.1) and a Fourth Step (4.2.2) formed to create a Second Angle (H) between them; and the Housing (7) comprises Cooling Slots (5) formed around the IR LED Housing (3).

[0044] The feature of the housing (7) is that it is made of aluminium-based material, metal, or coated plastic material.

[0045] The Camera (6) is placed into the Camera Housing (9) on the Housing (7); and the IR LED (2) is placed into the IR LED Housing (3). The surfaces of the Camera (6) and IR LED (2) are covered with the IR Filter (1). The back surface of the Housing (7) is closed by the Back Cover (8), thereby assembling the parts of the reflector.

[0046] The image of the driver illuminated by the IR LEDs (2) is captured by the Camera (6). The light emitted by the IR LEDs (2) first reflects off the aluminium Inner Surface of IR LED Housing Reflector (4), then reflects through the IR Filter (1) and reaches the Camera (6).

[0047] When the intensity of light reaching the Camera (6) is high, light rings occur, and the image of the driver becomes distorted. To reduce the intensity of the light reaching the Camera (6) by altering its path through internal reflections, stepped surfaces are formed on the Inner Surface of IR LED Housing Reflector (4).

[0048] At least one surface on the Inner Surface of IR LED Housing Reflector (4) has been stepped. The light flux reflected through the IR Filter (1) mostly comes from the First Surface (4.1) located on the side wall of the Inner Surface of IR LED Housing Reflector (4) and from the Second Surface (4.2) located on the side wall of the Camera Housing (9). Therefore, in the optimal application of the invention, both the First Surface (4.1) and Second Surface (4.2) are stepped.

[0049] The first stepped surface is preferably the First Surface (4.1) on the side wall of the Inner Surface of IR LED Housing Reflector (4). The First Surface (4.1) is formed with the First Step (4.1.1) and Second Step (4.1.2), creating a First Angle (G) between them. The First Step (4.1.1) also forms a First Base Angle (I). Under optimal conditions, the First Step Height (C) is greater than the Second Step Height (D).

[0050] OD

[0051] Also under optimal conditions, the First Angle (G) between the First Step (4.1.1) and the Second Step (4.1.2) of the First Surface (4.1) is less than 180° and greater than 90°.

[0052] 180°>G>90°

[0053] Additionally, the First Base Angle (I) is created to be less than 90°.

[0054] I<90°

[0055] The second stepped surface is the Second Surface (4.2), which is on the side wall of the Camera Housing (9). The Second Surface (4.2) is formed with the Third Step (4.2.1) and the Fourth Step (4.2.2), creating a Second Angle (H) between them. The Third Step (4.2.1) also forms a Second Base Angle (J). Under optimal conditions, the Third Step Height (F) is greater than the Fourth Step Height (E).

[0056] F>E

[0057] Also under optimal conditions, the Second Angle (H) between the Third Step (4.2.1) and Fourth Step (4.2.2) is greater than 180°.

[0058] 180°<H

[0059] Additionally, the Second Base Angle (J) is formed to be less than 90°. J<90°

[0060] In alternative configurations of the invention, the number of stepped surfaces, their positions, sizes, and angles may vary. The light emitted by the IR LEDs (2) first reflects off the Inner Surface of IR LED Housing Reflector (4). Therefore, heating occurs on the Inner Surface of IR LED Housing Reflector (4) and correspondingly in the Housing (7). The long-term and efficient operation of DMS and QMS cameras depends on stable temperature conditions. Thus, another problem solved by the invention is to provide cooling by maximizing heat transfer via increased surface area of the Housing (7) without integrating any cooling device. For this purpose, Cooling Slots (5) are formed on the Housing (7). These Cooling Slots (5) may be distributed across the entire Housing (7) or, under optimal conditions, concentrated around the part of the Housing (7) surrounding the IR LED Housing (3).

Claims

CLAIMS1. The invention is a reflector for DMS and OMS cameras, comprising at least one IR LED (2) within the Housing (7), the said IR LED (2) being located inside the IR LED Housing (3), and the said IR LED Housing (3) comprising the Inner Surface of IR LED Housing Reflector (4); characterized in that: the side wall of the Inner Surface of IR LED Housing Reflector (4) comprises a First Surface (4.1) including at least two steps formed to create a First Angle (G); and / or the wall of the Camera Housing (9) in the Inner Surface of IR LED Housing Reflector (4) comprises a Second Surface (4.2) including at least two steps formed to create a Second Angle (H).

2. A reflector according to Claim 1 for DMS and OMS cameras, characterized in that: the Second Surface (4.2) comprises a Third Step (4.2.1) and a Fourth Step (4.2.2).

3. A reflector according to Claim 1 for DMS and OMS cameras, characterized in that: the First Surface (4.1) comprises a First Step (4.1.1) and a Second Step (4.1.2).

4. A reflector according to Claim 1 for DMS and OMS cameras, characterized in that: Cooling Slots (5) are formed on the Housing (7) around the IR LED Housing (3).

5. A reflector according to Claim 1 for DMS and OMS cameras, characterized in that: the First Step Height (C) is greater than the Second Step Height(D).

6. A reflector according to Claim 1 for DMS and OMS cameras, characterized in that: the Third Step Height (F) is greater than the Fourth Step Height(E).

7. A reflector according to Claim 1 for DMS and QMS cameras, characterized in that: the First Angle (G) between the First Step (4.1.1) and Second Step (4.1.2) of the First Surface (4.1) is less than 180°.

8. A reflector according to Claim 1 for DMS and QMS cameras, characterized in that: the First Angle (G) between the First Step (4.1.1) and Second Step (4.1.2) of the First Surface (4.1) is greater than 90°.

9. A reflector according to Claim 1 for DMS cameras, characterized in that: the Second Angle (H) between the Third Step (4.2.1) and Fourth Step (4.2.2) of the Second Surface (4.2) is greater than 90°.

10. A reflector according to Claim 1 for DMS and QMS cameras, characterized in that: the Housing (7) is made of aluminium and / or aluminium-based material and / or metal and / or coated plastic.

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