Display screen brightness adjusting method

Abstract

The invention provides a display screen brightness adjusting method, which comprises the following steps of: 1, acquiring the brightness of ambient light outside a vehicle, judging whether the brightness of the ambient light outside the vehicle is lower than a preset brightness threshold value or not, if so, adjusting the brightness of all display screens to the lowest brightness and entering the next step, otherwise, keeping the current brightness of all display screens and then circularly executing the step; 2, the current speed of the vehicle is obtained, whether the current speed is larger than a preset speed threshold value or not is judged, if yes, the next step is executed, and if not, the step 1 is executed again; step 3, acquiring the sight direction of the driver; and 4, judging whether the sight direction of the driver moves to a target display screen area or not, if so, adjusting the brightness of the target display screen, and otherwise, returning to the step 1. According to the invention, intelligent adjustment of the brightness of the target display screen is realized, and the driving safety is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of displays, and in particular, to a method for adjusting the brightness of a display screen. Background Art

[0002] With the gradual popularization of intelligent cockpits in new energy vehicles, the size of in-vehicle display screens is getting larger and the number is increasing. When the in-vehicle display screen is lit, if the brightness is too high, it is very likely to become a source of interference for the driver, especially when driving at night.

[0003] Currently, in order to reduce the light interference after the display screen is lit, the brightness of the display screen is mainly adjusted manually by the driver. However, this operation method is obviously a relatively large hidden danger for safe driving. Another method is to adjust the brightness through the voice assistant built into the vehicle system. However, since the working states of each display screen are different, the required display brightness is also different. Therefore, this method requires voice commands to be input one by one to adjust the brightness of each display screen, and the interaction logic is complex, resulting in a poor user experience. Summary of the Invention

[0004] The present invention provides a method for adjusting the brightness of a display screen, aiming to solve the defects in the prior art, realize the intelligent adjustment of the brightness of the target display screen, and improve driving safety.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] The present invention provides a method for adjusting the brightness of a display screen, including:

[0007] Step 1: Obtain the brightness of the external ambient light, and determine whether the brightness of the external ambient light is lower than a preset brightness threshold. If so, adjust the brightness of all display screens to the lowest brightness and proceed to the next step; otherwise, keep the current brightness of all display screens and loop to execute this step;

[0008] Step 2: Obtain the current vehicle speed, and determine whether the current vehicle speed is greater than a preset speed threshold. If so, proceed to the next step; otherwise, return to Step 1;

[0009] Step 3: Obtain the line-of-sight direction of the driver;

[0010] Step 4: Determine whether the line-of-sight direction of the driver moves to the target display screen area. If so, adjust the brightness of the target display screen; otherwise, return to Step 1.

[0011] Specifically, Step 3 includes:

[0012] Step 301: Establish a camera coordinate system, obtain the head image of the driver when looking straight ahead, and generate a reference image;

[0013] Step 302: Identify the reference image to obtain the coordinates of the upper left corner of the face frame of the target eye, the length of the face frame, and the height of the face frame, which are used as the reference face frame coordinates, the reference face frame length, and the reference face frame height, respectively;

[0014] Step 303: Obtain the real-time image of the driver's head, and identify the real-time image to obtain the pupil position of the target eye, the coordinates of the upper left corner of the face frame, the length of the face frame, and the height, which are used as the real-time pupil position, the real-time face frame coordinates, the real-time face frame length, and the real-time face frame height, respectively;

[0015] Step 304: Correct the real-time pupil position according to the first preset relationship to obtain the corrected pupil position;

[0016] Step 305: Determine the line-of-sight direction of the driver according to the corrected pupil position.

[0017] Specifically, the first preset relationship is:

[0018] a' = [a c +(m c -m 0 )] / (l 0 / l c )

[0019] b' = [b c +(n c -n 0 )] / (h 0 / h c )

[0020] where (a', b') represents the corrected pupil position, (a c , b c ) represents the real-time pupil position, (m 0 , n 0 ) represents the reference face frame coordinates, (m c , n c ) represents the real-time face frame coordinates, l 0 represents the reference face frame length, l c represents the real-time face frame length, h 0 represents the reference face frame height, h c represents the real-time face frame height.

[0021] Specifically, step 305 includes: comparing the corrected pupil position with the real-time pupil position, and if the error is less than the preset value, determining the corrected pupil position as the corresponding line-of-sight direction.

[0022] Specifically, adjusting the brightness of the target display screen includes:

[0023] Step 401: Read the current in-vehicle ambient light brightness value and the auxiliary brightness value data, and calculate the historical average value of the auxiliary brightness value data, where the auxiliary brightness value data is the latest historical value of a preset number of in-vehicle ambient light brightness values;

[0024] Step 402: Calculate the current average value according to the second preset relational expression;

[0025] Step 403: Determine whether the change rate of the current average value is greater than the preset change threshold. If so, adjust the brightness of the target display screen according to the third preset relational expression; otherwise, keep the current brightness of the target display screen unchanged and return to Step 401.

[0026] Specifically, the second preset relational expression is:

[0027] B ave = k * B ave(-1) +(1 - k) * B cur

[0028] Where B ave represents the current average value, B ave(-1) represents the historical average value, and k is a constant.

[0029] Specifically, the third preset relational expression is:

[0030]

[0031] Where L is the brightness of the target display screen after adjustment, L w represents the screen brightness of the target display screen in the all-white pixel state, L B represents the screen brightness of the target display screen in the all-black state, ρ represents the reflection coefficient of the target display screen, E represents the ambient light illumination, and B represents the ambient light brightness.

[0032] Specifically, the preset change threshold is 10% - 20%.

[0033] Further, after Step 4, it further includes:

[0034] Step 5: Monitor the driver's eyes, and determine whether the eye shape is a slightly closed shape or a wide-open shape. If so, proceed to the next step; otherwise, return to Step 3;

[0035] Step 6: If the eye shape is a slightly closed shape, reduce the brightness of the target display screen by a preset step length and return to Step 3; if the eye shape is a wide-open shape, increase the brightness of the target display screen by a preset step length and return to Step 3.

[0036] The beneficial effects of the present invention are as follows: By obtaining the brightness of the external ambient light of the vehicle, when the brightness of the external ambient light is lower than the preset brightness threshold, the brightness of all displays is adjusted to the lowest brightness, and then the current vehicle speed is further obtained. If the current vehicle speed is greater than the preset speed threshold, the line-of-sight direction of the driver is obtained through a preset algorithm, and the brightness of the target display corresponding to the line-of-sight direction is adjusted, thereby realizing the intelligent adjustment of the brightness of the target display and improving driving safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a schematic flowchart of the display brightness adjustment method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0038] The embodiments of the present invention will be specifically described below in conjunction with the accompanying drawings. The accompanying drawings are only for reference and illustration, and do not constitute a limitation on the protection scope of the present invention patent.

[0039] In the processes described in the specification, claims or drawings of the present invention, which include the serial numbers of each step (such as step 10, 20, etc.), the serial numbers are only used to distinguish each step, and the serial numbers themselves do not represent any execution order. It should be noted that the descriptions such as "first" and "second" in this article are only used to distinguish the described objects, etc., and do not represent the sequence, nor do they mean that "first", "second", etc. are different types.

[0040] As Figure 1 shown, the present proposal provides a display brightness adjustment method, including:

[0041] Step 1: Obtain the brightness of the external ambient light of the vehicle, and determine whether the brightness of the external ambient light is lower than the preset brightness threshold. If so, adjust the brightness of all displays to the lowest brightness and proceed to the next step; otherwise, maintain the current brightness of all displays and loop to execute this step.

[0042] In specific implementation, the ambient light brightness can be detected by a photoelectric sensor, or can be realized by an image sensor. The present invention does not limit this.

[0043] By adjusting the brightness of all displays to the lowest brightness after the brightness of the external ambient light of the vehicle is lower than a certain value, the light interference of the displays is avoided.

[0044] Step 2: Obtain the current vehicle speed of the vehicle, and determine whether the current vehicle speed is greater than the preset speed threshold. If so, proceed to the next step; otherwise, return to Step 1.

[0045] In specific implementation, the vehicle speed can be detected by a vehicle speed sensor, such as an electromagnetic induction type vehicle speed sensor, a photoelectric type vehicle speed sensor, a variable reluctance type or a Hall type vehicle speed sensor, etc.

[0046] Step 3: Obtain the line of sight direction of the driver.

[0047] In this proposal, Step 3 includes:

[0048] Step 301: Establish a camera coordinate system, obtain the head image of the driver when looking straight ahead, and generate a reference image.

[0049] In specific implementation, by installing a camera in the vehicle, establishing the coordinate system of this camera, and taking the head image of the driver when looking straight ahead, a reference image is generated.

[0050] Step 302: Identify the reference image, and obtain the coordinates of the upper left corner of the face frame of the target eye, the length of the face frame, and the height of the face frame, which are respectively used as the reference face frame coordinates (m 0 , n 0 ), the reference face frame length l 0 , and the reference face frame height h 0 .

[0051] Step 303: Obtain the real-time image of the driver's head, and identify the real-time image to obtain the pupil position of the target eye, the coordinates of the upper left corner of the face frame, the length of the face frame, and the height, which are respectively used as the real-time pupil position (a c , b c ), the real-time face frame coordinates (m c , n c ), the real-time face frame length l c , and the real-time face frame height h c .

[0052] Step 304: Correct the real-time pupil position (a c , b c ) according to the first preset relational expression to obtain the pupil correction position (a', b').

[0053] In this proposal, the first preset relational expression is:

[0054] a' = [a c + (m c - m 0 )] / (l 0 / l c )

[0055] b' = [b c + (n c - n 0 )] / (h 0 / h c )

[0056] Among them, (a', b') represents the pupil correction position, (a c , bc ), which represents the real-time pupil position, (m 0 , n 0 ), which represents the reference face frame coordinates, (m c , n c ), which represents the real-time face frame coordinates, l 0 represents the length of the reference face frame, l c represents the length of the real-time face frame, h 0 represents the height of the reference face frame, h c represents the height of the real-time face frame.

[0057] Step 305: Determine the driver's line of sight direction according to the pupil correction position (a', b').

[0058] In this proposal, step 305 includes: comparing the pupil correction position (a', b') with the real-time pupil position (a c , b c ). If the error is less than a preset value, determine the pupil correction position (a', b') as the corresponding line of sight direction.

[0059] Step 4: Determine whether the driver's line of sight direction has moved to the target display area. If so, adjust the brightness of the target display, otherwise return to step 1.

[0060] In this proposal, adjusting the brightness of the target display includes:

[0061] Step 401: Read the current in-vehicle ambient light brightness value B cur and the auxiliary brightness value data, and calculate the historical average value B ave(-1) of the auxiliary brightness value data. The auxiliary brightness value data is the latest historical value of a preset number of in-vehicle ambient light brightness values.

[0062] Step 402: Calculate the current average value B ave according to the second preset relationship.

[0063] In this proposal, the second preset relationship is:

[0064] B ave = k * B ave(-1) + (1 - k) * B cur

[0065] where B ave represents the current average value, B ave(-1) represents the historical average value, and k is a constant.

[0066] The value of the constant k is obtained through calibration. The larger k is, the more obvious the smoothing is, that is, the less affected by the current ambient light, and vice versa, the more affected by the current ambient light.

[0067] Step 403: Determine whether the change rate of the current average value B ave is greater than a preset change threshold. If so, adjust the brightness of the target display screen according to a third preset relational expression; otherwise, keep the current brightness of the target display screen unchanged and return to Step 401.

[0068] In this proposal, the third preset relational expression is:

[0069]

[0070] where L is the brightness of the adjusted target display screen, L w represents the screen brightness of the target display screen under all-white pixels, L B represents the screen brightness of the target display screen in the all-black state, ρ represents the reflection coefficient of the target display screen, E represents the ambient light illumination, and B represents the ambient light brightness.

[0071] L w 、L B 、ρ can be obtained through calibration, and E and B can be measured by an ambient light sensor.

[0072] In this proposal, the preset change threshold is 10% - 20%.

[0073] In another proposal of the present invention, after the said Step 4, it further includes:

[0074] Step 5: Monitor the driver's eyes, and determine whether the eye shape is a slightly closed shape or an open shape. If so, proceed to the next step; otherwise, return to Step 3.

[0075] Step 6: If the eye shape is a slightly closed shape, reduce the brightness of the target display screen by a preset step size and return to Step 3; if the eye shape is an open shape, increase the brightness of the target display screen by a preset step size and return to Step 3.

[0076] The above-disclosed are only the preferred embodiments of the present invention, and the scope of the patent protection of the present invention cannot be limited thereby. Therefore, equivalent changes made according to the scope of the patent application of the present invention still fall within the scope covered by the present invention.

Claims

1. A method for adjusting display brightness, characterized in that: include: Step 1: Obtain the brightness of the ambient light outside the vehicle, and determine whether the brightness of the ambient light outside the vehicle is lower than a preset brightness threshold. If yes, adjust the brightness of all display screens to the minimum brightness and proceed to the next step; otherwise, maintain the current brightness of all display screens and execute this step in a loop; Step 2, obtaining the current speed of the vehicle, and determining whether the current speed is greater than a preset speed threshold, if yes, proceed to the next step, otherwise, return to step 1; Step 3, obtaining the driver's sight direction; Step 4: determine whether the driver's line of sight moves to the target display screen area, if yes, adjust the brightness of the target display screen, otherwise return to step 1.

2. The display screen brightness adjustment method according to claim 1, characterized in that: The step 3 comprises: Step 301, establish a camera coordinate system, obtain the head image of the driver when looking forward, and generate a reference image; Step 302, identifying the reference image, obtaining the coordinates of the upper left corner of the face frame of the target eye, the face frame length, and the face frame height, which are used as the reference face frame coordinates, the reference face frame length, and the reference face frame height, respectively; Step 303: Acquire a real-time image of the driver's head, identify the real-time image, and acquire the pupil position of the target eye, the coordinates of the upper left corner of the face frame, the length and height of the face frame as the real-time pupil position, the real-time face frame coordinates, the real-time face frame length, and the real-time face frame height, respectively; Step 304: correcting the real-time pupil position according to the first preset relationship to obtain a corrected pupil position; Step 305: Determine the driver's sight direction according to the corrected pupil position.

3. The display screen brightness adjustment method according to claim 2, characterized in that: The first preset relationship is: a'=[a c +(m c -m0)] / (l0 / l c ) b'=[b c +(n c -n0)] / (h0 / h c ) Among them, (a', b') represents the corrected pupil position, (a c ,b c ) represents the real-time pupil position, (m0,n0) represents the reference face frame coordinates, (m c ,n c ) represents the real-time face frame coordinates, l0 represents the reference face frame length, l c represents the real-time face frame length, h0 represents the base face frame height, h c Indicates the real-time face frame height.

4. The display screen brightness adjustment method according to claim 3, characterized in that: The step 305 includes: comparing the corrected pupil position with the real-time pupil position, and if the error is less than a preset value, determining the corrected pupil position as the corresponding sight line direction.

5. The display screen brightness adjustment method according to claim 1, characterized in that: The step of adjusting the brightness of the target display screen comprises: Step 401, reading the current in-vehicle ambient light brightness value and auxiliary brightness value data, and calculating the historical average value of the auxiliary brightness value data, wherein the auxiliary brightness value data is the latest historical value of a preset number of in-vehicle ambient light brightness values; Step 402, calculating the current average value according to the second preset relationship; Step 403 , determining whether the rate of change of the current average value is greater than a preset change threshold, if so, adjusting the brightness of the target display screen according to a third preset relationship, otherwise keeping the current brightness of the target display screen unchanged and returning to step 401 .

6. The method for adjusting display screen brightness according to claim 5, characterized in that: The second preset relationship is: B ave =k*B ave(-1) +(1-k)*B cur Among them, B ave Indicates the current average value, B ave(-1) represents the historical average, and k is a constant.

7. The display screen brightness adjustment method according to claim 6, characterized in that: The preset change threshold is 10% to 20%.

8. The method for adjusting display screen brightness according to claim 5, characterized in that: The third preset relationship is: Where, L is the brightness of the target display screen after adjustment, L w Indicates the screen brightness of the target display under full white pixels, L B represents the screen brightness of the target display in a completely black state, ρ represents the reflection coefficient of the target display, E represents the ambient light illumination, and B represents the ambient light brightness.

9. The display screen brightness adjustment method according to claim 1, characterized in that: After step 4, the method further includes: Step 5: monitor the driver's eyes and determine whether the eye shape is slightly closed or wide open. If yes, proceed to the next step; otherwise, return to step 3; Step 6: If the eye shape is slightly closed, the brightness of the target display screen is reduced by a preset step size, and the process returns to step 3; if the eye shape is wide open, the brightness of the target display screen is increased by a preset step size, and the process returns to step 3.

Images