Rear-view mirror having automatic brightness control function and control method thereof

Abstract

According to the present invention, disclosed are a rear-view mirror having an automatic brightness control function and a control method thereof. A rear-view mirror according to a preferred embodiment of the present invention adjusts the brightness of a display by analyzing a forward image input from a front camera in a display mode and adjusts the transmittance of a mirror module by analyzing a rear image input from a rear camera in a mirror mode, according to a use mode set by a user, thus making it possible to automatically adjust the brightness of the display of the rear-view mirror without installing an optical sensor, and resolve glare caused by the headlights of a trailing vehicle at night.

Description

Rear-view mirror equipped with automatic brightness adjustment function and control method thereof

[0001] The present invention relates to a rearview mirror and a method for controlling the same, and more specifically, to a rearview mirror equipped with an automatic brightness adjustment function and a method for controlling the same.

[0002] Recently released vehicles are equipped with convenience features that provide drivers with useful information regarding driving. One of these is the digital rear-view mirror. Conventional rear-view mirrors simply performed the function of displaying the rear view seen through the vehicle's rear window to the driver via a mirror. However, these conventional rear-view mirrors have the disadvantage of failing to function properly when the rear window is heavily dusty or covered in snow.

[0003] To overcome these problems, digital rear-view mirrors have been developed and are being supplied. Digital rear-view mirrors install a camera at the rear of the vehicle and capture the rear view of the vehicle through the camera, displaying it to the driver, thereby enabling the driver to check the situation behind the vehicle.

[0004] Conventional rear-view mirrors used light sensors to automatically or manually adjust the brightness of the display according to the amount of ambient light in order to ensure the driver's visibility during the day and night and to reduce fatigue. However, since the amount of ambient light measured varies depending on the position of the light sensor, it was difficult to accurately reflect the driving environment and adjust the brightness of the display, and it could not respond in real time to changes in the driving environment. Furthermore, there was a disadvantage in that the digital rear-view mirror could not perform properly due to a failure of the light sensor.

[0005] The problem that the present invention aims to solve is to provide a rear-view mirror equipped with automatic brightness adjustment capability and a control method thereof, which solves the problems of the prior art that occur when automatically adjusting the brightness of a display using a light sensor.

[0006] A rearview mirror equipped with an automatic brightness adjustment function according to a preferred embodiment of the present invention for solving the above-mentioned problem comprises: a camera module including a rear camera that captures the rear of a vehicle and outputs a rear image, and a front camera that captures the front of a vehicle and outputs a front image; a display that outputs the rear image; a mirror module installed in front of the display and adjusting the transmittance of light passing through according to a control signal; and a circuit unit including a processor and a memory, wherein the processor can, according to a usage mode set by a user, analyze the front image input from the front camera in the display mode to adjust the brightness of the display, and analyze the rear image input from the rear camera in the mirror mode to adjust the transmittance of the mirror module.

[0007] In addition, the processor can calculate the brightness, contrast ratio, and saturation of the front image, respectively, and adjust the brightness of the display by calculating the weighted average of the brightness, contrast ratio, and saturation.

[0008] In addition, the above processor

[0009] [Mathematical Formula 1]

[0010]

[0011] [Mathematical Formula 2]

[0012]

[0013] [Mathematical Formula 3]

[0014]

[0015] Brightness (L) can be calculated according to the above mathematical formula 1, contrast ratio (C) according to the above mathematical formula 2, and saturation (S) according to the above mathematical formula 3.

[0016] In addition, the above processor calculates the video total score according to the following mathematical formula 4, and

[0017] [Mathematical Formula 4]

[0018] Video Comprehensive Score = (ωL*Ln)+(ωC*C)+(ωS*S)

[0019] (L = Brightness, C = Contrast, S = Saturation, Ln = L / 255, ωL = Brightness weight, ωC = Contrast weight, ωS = Saturation weight)

[0020] The brightness of the display can be adjusted in steps according to the predefined range of the video total score.

[0021] In addition, the processor can detect the headlight area of ​​a vehicle moving in the rear from a rear image, calculate a headlight brightness score using the area of ​​the headlight area and the luminance value of the brightest pixel in the area, and adjust the transmittance of the mirror module according to the headlight brightness score.

[0022] In addition, the processor calculates the brightness score of the headlights according to the following mathematical formula 5, and

[0023] [Mathematical Formula 5]

[0024]

[0025] (A = Area of ​​the headlight region, Ymax = Luminance value of the brightest pixel in the headlight region)

[0026] The transmittance of the mirror module can be adjusted to the transmittance of a predefined range corresponding to the brightness score of the headlight.

[0027] Meanwhile, a control method according to a preferred embodiment of the present invention for solving the above-mentioned problem is a control method for a rear-view mirror comprising a camera module including a rear camera and a front camera, a display, a mirror module installed in front of the display to adjust transmittance according to a control signal, and a circuit unit having a processor and a memory, wherein the method comprises: (a) a step in which a processor checks a usage mode set by a user; (b) a step in which, when the usage mode is a display mode, the processor analyzes a front image input from the front camera and adjusts the brightness of the display; and (c) a step in which, when the usage mode is a mirror mode, the processor analyzes a rear image input from the rear camera and adjusts the transmittance of the mirror module.

[0028] Additionally, in step (b) above, the processor can calculate the brightness, contrast ratio, and saturation of the front image, respectively, and calculate the weighted average of the brightness, contrast ratio, and saturation to adjust the brightness of the display.

[0029] In addition, in step (b) above, the processor

[0030] [Mathematical Formula 1]

[0031]

[0032] [Mathematical Formula 2]

[0033]

[0034] [Mathematical Formula 3]

[0035]

[0036] Brightness (L) can be calculated according to the above mathematical formula 1, contrast ratio (C) according to the above mathematical formula 2, and saturation (S) according to the above mathematical formula 3.

[0037] In addition, in step (b) above, the processor

[0038] Calculate the video total score according to the mathematical formula 4 below, and

[0039] [Mathematical Formula 4]

[0040] Video Comprehensive Score = (ωL*Ln)+(ωC*C)+(ωS*S)

[0041] (L = Brightness, C = Contrast, S = Saturation, Ln = L / 255, ωL = Brightness weight, ωC = Contrast weight, ωS = Saturation weight)

[0042] The brightness of the display can be adjusted in steps according to the predefined range of the video total score.

[0043] In addition, in step (c) above, the processor detects the headlight area of ​​a vehicle operating in the rear from the rear image, calculates a brightness score of the headlight using the area of ​​the headlight area and the luminance value of the brightest pixel in the area, and can adjust the transmittance of the mirror module according to the headlight brightness score.

[0044] In addition, in step (c) above, the processor

[0045] Calculate the headlight brightness score according to mathematical formula 5 below, and

[0046] [Mathematical Formula 5]

[0047]

[0048] (A = Area of ​​the headlight region, Ymax = Luminance value of the brightest pixel in the headlight region)

[0049] The transmittance of the mirror module can be adjusted to the transmittance of a predefined range corresponding to the brightness score of the headlight.

[0050] A rear-view mirror according to a preferred embodiment of the present invention can automatically adjust the brightness of the rear-view mirror's display without installing a light sensor and eliminate glare caused by the headlights of following vehicles at night by analyzing the front image input from a front camera in display mode and adjusting the transmittance of the mirror module in mirror mode according to a usage mode set by a user.

[0051] FIGS. 1A and FIGS. 1B are drawings illustrating the configuration of a rear-view mirror according to a preferred embodiment of the present invention.

[0052] FIG. 2 is a flowchart illustrating a method for controlling a rear-view mirror according to a preferred embodiment of the present invention.

[0053] FIG. 3 is a drawing illustrating the installation environment of a rear-view mirror equipped with an automatic brightness adjustment function according to a preferred embodiment of the present invention.

[0054] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0055] Hereinafter, the aforementioned objects, features, and advantages of the present invention will become more apparent from the following detailed description in conjunction with the accompanying drawings. However, as the present invention is subject to various modifications and may have various embodiments, specific embodiments are illustrated in the drawings and described in detail below.

[0056] Throughout the specification, identical reference numbers indicate identical components in principle. Additionally, components with identical functions within the scope of the same concept appearing in the drawings of each embodiment are described using the same reference numeral.

[0057] When a part of a specification is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Furthermore, terms such as "...part" or "module" as used in the specification refer to a unit that processes at least one function or operation, and this may be implemented in hardware or software, or as a combination of hardware and software.

[0058] If it is determined that a detailed description of known functions or configurations related to the present invention may unnecessarily obscure the essence of the present invention, such detailed description is omitted. Additionally, numbers used in the description of this specification (e.g., 1st, 2nd, etc.) are merely identification symbols to distinguish one component from another.

[0059] FIGS. 1a and 1b are drawings illustrating the configuration of a rear-view mirror equipped with an automatic brightness adjustment function according to a preferred embodiment of the present invention, FIG. 2 is a flowchart explaining a method for controlling a rear-view mirror according to a preferred embodiment of the present invention, and FIG. 3 is a drawing explaining the installation environment of a rear-view mirror equipped with an automatic brightness adjustment function according to a preferred embodiment of the present invention.

[0060] Referring to FIGS. 1a to 2, a rear-view mirror (hereinafter abbreviated as 'rear-view mirror') (100) having an automatic brightness adjustment function according to a preferred embodiment of the present invention includes a camera module (110), a mirror module (140), a display (130), and a circuit unit (120). The circuit unit (120) includes a processor (121) and a memory (123). The camera module (110) basically includes a rear camera (111) and a front camera (113). The mirror module (140), the display (130), and the circuit unit (120) are contained in a rear-view mirror housing (190) and installed near the front windshield of the vehicle interior.

[0061] A rear camera (111) is installed on the exterior rear of the vehicle, captures the rear of the vehicle to generate a rear image, and transmits the rear image to a processor (121). The rear camera (111) may be used to have a shooting angle of 120 degrees or more so that blind spots can be captured.

[0062] The front camera (113) is installed inside the rear-view mirror housing (190) to face forward, captures a front image, and outputs the captured front image to the processor (121). Additionally, the front camera (113) of the present invention may be shared with other components of the vehicle. For example, the front camera (113) of the present invention may be implemented as a front camera included in a driving video recording device (built-in cam, vehicle black box, etc.) installed in the vehicle, or as a front camera included in the vehicle's ADAS system to capture the front.

[0063] The display (130) can be implemented as an LCD module, an OLED module, etc., and is turned on / off according to the control of the processor (121), and outputs a video signal generated by the processor (121).

[0064] The mirror module (140) contains an EC (Electronic Chromic) film inside and is positioned in front of the display (130). Under the control of the processor (121), the reflectivity and transmittance of the EC film contained in the mirror module (140) are adjusted, and accordingly, the mirror module (140) performs the role of a reflector or transmits an image displayed on the display (130) so that the driver and passengers can see the image on the display (130).

[0065] The mirror module (140) exhibits a phenomenon in which the image displayed on the mirror module (140) becomes darker as the transmittance decreases and the image displayed on the mirror module (140) becomes brighter as the transmittance increases, which is the same as the phenomenon exhibited by conventionally commercialized ECM (Electronic Chromic Mirror) mirrors.

[0066] In a preferred embodiment of the present invention, the mirror module (140) operates as an Electronic Chromic Mirror (ECM) when the display (130) is off. When the headlights of a vehicle traveling from behind are strongly reflected, the transmittance of the EC film is reduced by the control of the processor, thereby darkening the mirror module (140) and preventing glare from the headlights. Since the internal structure of the mirror module (140) may be identical to the structure of a known electronic chromic mirror, a description of the internal physical structure of the mirror module (140) is omitted.

[0067] The memory (123) is implemented as an SSD (Solid State Drive), flash memory, ROM (Read-Only Memory), RAM (Random Access Memory), etc., and can store instructions to be executed by the processor (121), and can store data processed by the processor (121) and rear images.

[0068] The processor (121) can be implemented as a CPU (Central Processing Unit) or a similar device (e.g., MPU (Micro Processing Unit), MCU (Micro Control Unit), etc.) and controls the display (130) and mirror module (140) by executing instructions stored in memory (123), processes the rear image to generate an image to be output to the display (130), and outputs the generated image through the display (130).

[0069] Additionally, the processor (121) analyzes the front image input from the front camera to adjust the brightness of the display (130) and analyzes the rear image input from the rear camera to adjust the transmittance of the mirror module (140), thereby enabling the brightness of the display (130) and the transmittance of the mirror module (140) to be naturally adjusted according to the ambient light and environment without using a light sensor.

[0070] With further reference to FIG. 2, the function and control method of the rear-view mirror of the present invention will be explained.

[0071] When the rear-view mirror of the present invention is driven, the processor checks the usage mode set by the user (S210), performs step S220 described below if the usage mode is a display mode, and performs step S230 described below if the usage mode is a mirror mode.

[0072] Specifically, when the usage mode is display mode, the processor receives a rear image from the rear camera and outputs it through the display (130), and receives a front image from the front camera (S221).

[0073] After that, the processor calculates brightness, contrast, and saturation from the front image (S223).

[0074] In a preferred embodiment of the present invention, the processor calculated brightness (L), contrast ratio (C), and saturation (S) respectively according to the following mathematical formulas 1 to 3.

[0075] [Mathematical Formula 1]

[0076]

[0077] [Mathematical Formula 2]

[0078]

[0079] [Mathematical Formula 3]

[0080]

[0081] The above R, G, and B represent pixel values ​​of the front image.

[0082] Table 1 below summarizes the types of surrounding environments that can be identified by brightness (L), contrast (C), and saturation (S).

[0083]

[0084] After that, the processor calculates an image comprehensive score that comprehensively represents the driving environment by substituting brightness (L), contrast ratio (C), and saturation (S) into the following mathematical formula 4 (S225).

[0085] [Mathematical Formula 4]

[0086] Video Comprehensive Score = (ωL*Ln)+(ωC*C)+(ωS*S)

[0087] In the above mathematical formula 4, Ln = L / 255, where ωL represents the brightness weight, ωC represents the contrast weight, and ωS represents the saturation weight. In a preferred embodiment of the present invention, ωL = 0.6, ωC = 0.25, and ωS = 0.15 were set, but the weight values ​​may be changed according to design specifications.

[0088] The video total score has a value of 0.0 to 1.0, and when the video total score is calculated, the processor adjusts the brightness of the display (130) according to the video total score (S227).

[0089] Generally, the brighter the surrounding environment, the higher the brightness, contrast ratio, and saturation of the front image, and accordingly, the overall image score increases, and in response, the processor adjusts the brightness of the display (130) to be high.

[0090] Additionally, the darker the surrounding environment, the lower the brightness, contrast ratio, and saturation of the front image, and accordingly, the overall image score is lowered, and in response, the processor lowers the brightness of the display (130).

[0091] In a preferred embodiment of the present invention, as shown in Table 2 below, the brightness level is divided into 6 levels according to the range of the image total score and stored in memory, and the brightness of the display (130) is adjusted to the brightness level corresponding to the calculated image total score.

[0092] Video Overall Score Range Display Brightness Level 0.90~1.00 100% 0.75~0.90 90% 0.55~0.75 80% 0.35~0.55 70% 0.15~0.35 60% 0.00~0.15 50%

[0093] Meanwhile, in the above-described step S210, when the usage mode is mirror mode, the processor receives a rear image and detects a headlight area in the rear area (S231).

[0094] The headlight area is an area in the rear image with significantly higher brightness than the surrounding area. The processor can detect the headlight area by searching for clusters of pixels in the rear image with brightness higher than a threshold than the surrounding area, and can also detect the headlight area using various other algorithms.

[0095] In this case, when a following vehicle is driving with its headlights on during the day, the headlight area included in the rear image may not be detected because the difference in brightness compared to the surrounding area is not significantly large. Therefore, the present invention is useful for night driving or on days when the surroundings are dark due to bad weather.

[0096] Meanwhile, when a headlight is detected in the rear image, the processor calculates the area of ​​the headlight and calculates the maximum luminance value in the headlight area (S235). The area of ​​the headlight can be calculated by counting the number of pixels included in the area when the headlight area is detected.

[0097] After that, the processor calculates the headlight brightness score (S237).

[0098] In a preferred embodiment of the present invention, the processor can calculate the brightness score of the headlight according to the following mathematical formula 5.

[0099] [Mathematical Formula 5]

[0100]

[0101] (A = Area of ​​the headlight region, Ymax = Luminance value of the brightest pixel in the headlight region)

[0102] The above mathematical formula 5 reflects the light intensity and distance effects of the headlights in the rear image at once, but prevents the brightness score from increasing rapidly by using the square root of the area.

[0103] Next, the processor adjusts the transmittance of the mirror module (140) according to the brightness score of the headlight (S239).

[0104] In a preferred embodiment of the present invention, the processor determines the transmittance corresponding to the brightness score of the headlight according to Table 3 below, and accordingly adjusts the voltage applied to the EC film to control the transmittance of the mirror module (140) (i.e., the transmittance of the EC film included in the mirror module (140)).

[0105] Headlight Brightness Score Transmittance Perceived Situation 6,000 or less: 80% (Almost transparent) Long distance Weak light 6,000~12,000: 50% (Medium) Approaching normal passenger car 12,000 or more: 20% (Maximum blockage) Close range & High beam

[0106] As transmittance decreases, the image displayed on the mirror module (140) becomes darker, and as transmittance increases, the image displayed on the mirror module (140) becomes brighter, which is the same as the conventional ECM.

[0107] For reference, the further the trailing vehicle is, the smaller the area occupied by the headlight region in the rear image, the smaller the brightness score of the headlight, and the greater the transmittance, so the image displayed on the mirror module (140) becomes brighter.

[0108] Likewise, as the trailing vehicle gets closer, the area occupied by the headlight region in the rear image increases, the brightness score of the headlight increases, the transmittance decreases, and the image displayed on the mirror module (140) becomes darker.

[0109] Steps S221 through S227 and steps S231 through S239 described above are performed repeatedly until the usage mode is changed.

[0110] The rear-view mirror control method having an automatic brightness adjustment function according to the preferred embodiment of the present invention described so far can be implemented as a computer program that is executed as a computer-executable instruction and stored in a non-transient storage medium.

[0111] Storage media include all types of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable storage media include ROM, RAM, CD-ROM, and optical data storage devices. Additionally, computer-readable storage media are distributed across networked computer systems, allowing computer-readable code to be stored and executed in a distributed manner.

[0112] The present invention has been described above with reference to its preferred embodiments. Those skilled in the art will understand that the present invention may be embodied in modified forms without departing from the essential characteristics of the invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the invention is defined by the claims, not by the foregoing description, and all variations within the scope of the claims should be interpreted as being included in the invention.

Claims

1. A camera module comprising a rear camera that captures the rear of a vehicle and outputs a rear image, and a front camera that captures the front of a vehicle and outputs a front image; A display that outputs the above rear image; A mirror module installed in front of the above display and controlling the transmittance of light passing through according to a control signal; and It includes a circuit section including a processor and memory, and The above processor Depending on the usage mode set by the user, In display mode, the brightness of the display is adjusted by analyzing the front image input from the front camera, and A rearview mirror equipped with an automatic brightness adjustment function, characterized by analyzing a rear image input from the rear camera in mirror mode to adjust the transmittance of the mirror module.

2. In claim 1, the processor A rearview mirror equipped with an automatic brightness adjustment function, characterized by calculating the brightness, contrast ratio, and saturation of a front image, respectively, and adjusting the brightness of the display by calculating the weighted average of the brightness, contrast ratio, and saturation.

3. In claim 2, the processor [Mathematical Formula 1] [Mathematical Formula 2] [Mathematical Formula 3] A rearview mirror equipped with an automatic brightness adjustment function, characterized by calculating brightness (L) according to the above mathematical formula 1, calculating contrast ratio (C) according to the above mathematical formula 2, and calculating saturation (S) according to the above mathematical formula 3.

4. In claim 3, the processor Calculate the video total score according to the mathematical formula 4 below, and [Mathematical Formula 4] Video Comprehensive Score = (ωL*Ln)+(ωC*C)+(ωS*S) (L = Brightness, C = Contrast, S = Saturation, Ln = L / 255, ωL = Brightness weight, ωC = Contrast weight, ωS = Saturation weight) A rearview mirror equipped with an automatic brightness adjustment function characterized by adjusting the brightness of the display in steps according to a predefined range of video total scores.

5. In claim 1, the processor A rearview mirror equipped with an automatic brightness adjustment function, characterized by detecting a headlight area of ​​a vehicle operating in the rear from a rear image, calculating a headlight brightness score using the area of ​​the headlight area and the luminance value of the brightest pixel in the area, and adjusting the transmittance of the mirror module according to the headlight brightness score.

6. In claim 5, the processor Calculate the headlight brightness score according to mathematical formula 5 below, and [Mathematical Formula 5] (A = Area of ​​the headlight region, Ymax = Luminance value of the brightest pixel in the headlight region) A rearview mirror equipped with an automatic brightness adjustment function characterized by adjusting the transmittance of a mirror module to the transmittance of a predefined range corresponding to the brightness score of a headlight.

7. A method for controlling a rear-view mirror comprising a camera module including a rear camera and a front camera, a display, a mirror module installed in front of the display to adjust transmittance according to a control signal, and a circuit unit having a processor and a memory, wherein (a) A step in which the processor checks the usage mode set by the user; (b) when the usage mode is a display mode, the processor analyzes a front image input from the front camera and adjusts the brightness of the display; and (c) A rearview mirror control method having an automatic brightness adjustment function, characterized in that when the usage mode is mirror mode, the processor analyzes a rear image input from the rear camera and adjusts the transmittance of the mirror module.

8. In Paragraph 7, In step (b) above, the processor A rearview mirror control method equipped with an automatic brightness adjustment function, characterized by calculating the brightness, contrast ratio, and saturation of a front image, respectively, and adjusting the brightness of the display by calculating the weighted average of the brightness, contrast ratio, and saturation.

9. In Paragraph 8, In step (b) above, the processor [Mathematical Formula 1] [Mathematical Formula 2] [Mathematical Formula 3] A rearview mirror control method equipped with an automatic brightness adjustment function, characterized by calculating brightness (L) according to the above mathematical formula 1, calculating contrast ratio (C) according to the above mathematical formula 2, and calculating saturation (S) according to the above mathematical formula 3.

10. In Paragraph 9, In step (b) above, the processor Calculate the video total score according to the mathematical formula 4 below, and [Mathematical Formula 4] Video Comprehensive Score = (ωL*Ln)+(ωC*C)+(ωS*S) (L = Brightness, C = Contrast, S = Saturation, Ln = L / 255, ωL = Brightness weight, ωC = Contrast weight, ωS = Saturation weight) A rearview mirror control method equipped with an automatic brightness adjustment function, characterized by adjusting the brightness of the display in steps according to a predefined range of video total scores.

11. In Paragraph 7, In step (c) above, the processor A rearview mirror control method equipped with an automatic brightness adjustment function, characterized by detecting a headlight area of ​​a vehicle operating in the rear from a rear image, calculating a headlight brightness score using the area of ​​the headlight area and the luminance value of the brightest pixel in the area, and adjusting the transmittance of the mirror module according to the headlight brightness score.

12. In Paragraph 11, In step (c) above, the processor Calculate the headlight brightness score according to mathematical formula 5 below, and [Mathematical Formula 5] (A = Area of ​​the headlight region, Ymax = Luminance value of the brightest pixel in the headlight region) A rearview mirror control method equipped with an automatic brightness adjustment function, characterized by adjusting the transmittance of a mirror module to the transmittance of a predefined range corresponding to the brightness score of a headlight.

13. A non-transient recording medium having the rearview mirror control method equipped with the automatic brightness adjustment function of claim 7 recorded as computer-readable and computer-executable program code.

Images