Image acquisition device and method, head-up display device, and control and judgment method

Abstract

The present disclosure relates to an image acquisition device, a head-up display device, an image acquisition method, a control method for a head-up display device, and a judgment method. In one aspect, an image acquisition device is provided, which receives light in a predetermined direction facing a windshield in a working state, wherein an extension line of the predetermined direction passes through a virtual image formed by an eye ellipse through the windshield and the angle between the predetermined direction and the normal direction of the windshield at the intersection of the extension line and the windshield is the Brewster angle or near the Brewster angle, and comprises: a polarization splitting element configured to split light to obtain P polarized light and S polarized light; an imaging module configured to separately image the P polarized light and the S polarized light to obtain a P light image and an S light image, respectively; and a processing module configured to obtain a driver's facial image based on the P light image and the S light image. Thus, the accuracy of adjusting the display brightness can be higher.

Description

Technical Field

[0001] The present disclosure relates to the field of display technology, and in particular, to an image acquisition device, a head-up display device, an image acquisition method, a control method for the head-up display device, and a judgment method. Background Art

[0002] Head Up Display (HUD) devices are widely used in vehicles and other transportation tools. They are used to project information such as vehicle conditions onto, for example, a windshield to form a display image, making it easier for the driver to obtain this information in front of his or her field of vision.

[0003] In order to enable the driver to clearly observe this information to improve driving safety, the display brightness of the HUD device and thus the brightness of the displayed image need to be adjusted according to the brightness of the external environment. For example, during the day when the external environment brightness is high, the display brightness of the HUD device needs to be increased, while at night or in tunnels when the external environment brightness is low, the display brightness of the HUD device needs to be reduced.

[0004] Existing HUD devices usually determine the brightness of the external environment based on the rain sensor signal, and adjust the display brightness of the HUD device accordingly. The rain sensor is generally set at a position close to the rearview mirror of the windshield and its sensing direction is close to the normal direction of the windshield. Therefore, the external environment brightness determined by the rain sensor signal is the environment brightness above the front of the vehicle, that is, the environment brightness above the outside of the windshield.

[0005] However, the area where the image is displayed is usually located directly in front of the vehicle, that is, in front of the outside of the windshield. Therefore, when the difference between the ambient brightness in front of the outside of the windshield and the ambient brightness above the outside is large, the HUD device often cannot accurately or even correctly adjust the display brightness, resulting in the display brightness being too high or too low, thereby affecting the driver's viewing of the displayed image and thus affecting driving safety. Summary of the invention

[0006] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

[0007] An object of the present disclosure is to provide a HUD device capable of accurately adjusting display brightness.

[0008] In order to achieve the above-mentioned object, according to one aspect of the present disclosure, an image acquisition device for acquiring a driver's facial image is provided, wherein the image acquisition device receives light in a predetermined direction facing a windshield in a working state, wherein an extension line of the predetermined direction passes through a virtual image formed by the eye ellipse through the windshield, and an angle between the predetermined direction and a normal direction of the windshield at an intersection of the extension line and the windshield is within a range of greater than or equal to the Brewster angle minus 10° to less than or equal to the Brewster angle plus 10°, and the image acquisition device comprises:

[0009] a polarization splitting element configured to split the received light to obtain P-polarized light and S-polarized light;

[0010] an imaging module configured to separately image the P-polarized light and the S-polarized light to obtain a P-light image and an S-light image, respectively; and

[0011] The processing module is configured to obtain the driver's facial image according to the P-light image and the S-light image.

[0012] In some embodiments, the angle may be in the range of 46.6° to 66.6°.

[0013] In some embodiments, the imaging module may include a first camera arranged to receive P-polarized light and configured to image the P-polarized light, and a second camera arranged to receive S-polarized light and configured to image the S-polarized light.

[0014] In some embodiments, the image acquisition device can be a camera, the camera includes a lens for receiving light, the polarization splitting element and the imaging module are arranged in the camera, and the imaging module includes a first sensor and a second sensor, the first sensor is arranged to receive P polarized light and configured to image the P polarized light, and the second sensor is arranged to receive S polarized light and configured to image the S polarized light.

[0015] In some embodiments, a linear polarization element may be further included, and the linear polarization element is arranged between the polarization beam splitting element and the imaging module on the optical path.

[0016] According to another aspect of the present disclosure, a HUD device is also provided, comprising:

[0017] An image generating unit configured to emit image light;

[0018] a reflective element configured to project image light incident thereon onto the windshield to form a display image;

[0019] The image acquisition device according to any one of the above embodiments; and

[0020] The processing unit is configured to control the output of the HUD device according to the driver's facial image acquired by the image acquisition device.

[0021] In some embodiments, a protective cover as the outermost side of the HUD device may be further included, and the image acquisition device is disposed on the inner side of the protective cover.

[0022] In some embodiments, the processing unit may be configured to adjust the display brightness of the HUD device based on the driver's facial image.

[0023] In some embodiments, the processing unit may be configured to adjust the display brightness of the HUD device according to the grayscale of the driver's facial image.

[0024] In some embodiments, the processing unit may be configured to adjust the display brightness of the HUD device according to the grayscale of the driver's facial image and the brightness of the displayed image.

[0025] In some embodiments, the processing unit may be configured to adjust the display brightness of the HUD device according to the grayscale of the driver's facial image and the grayscale of the P-light image.

[0026] In some embodiments, the processing unit may be configured to control at least one of the following outputs of the HUD device based on the driver's facial image: adjustment of eye box height, issuance of a fatigue warning signal, and issuance of a forward gaze warning signal.

[0027] According to another aspect of the present disclosure, there is also provided an image acquisition method for acquiring a driver's facial image, comprising:

[0028] Receive light in a predetermined direction facing the windshield, wherein an extension line of the predetermined direction passes through a virtual image formed by the eyellipse through the windshield, and an angle between the predetermined direction and a normal direction of the windshield at an intersection of the extension line and the windshield is within a range of greater than or equal to Brewster's angle minus 10° to less than or equal to Brewster's angle plus 10°;

[0029] Splitting the received light to obtain P-polarized light and S-polarized light;

[0030] Separately imaging the P-polarized light and the S-polarized light to obtain a P-light image and an S-light image, respectively; and

[0031] The driver's facial image is acquired based on the P-light image and the S-light image.

[0032] According to another aspect of the present disclosure, a control method for a head-up display device is provided, which includes controlling the output of the HUD device according to a driver's facial image, wherein the driver's facial image is a driver's facial image acquired according to the above-mentioned image acquisition method.

[0033] In some embodiments, controlling the output of the HUD device according to the driver's facial image may include: adjusting the display brightness of the HUD device according to the driver's facial image.

[0034] In some embodiments, adjusting the display brightness of the HUD device according to the driver's facial image includes: adjusting the display brightness of the HUD device according to the grayscale of the driver's facial image.

[0035] In some embodiments, adjusting the display brightness of the HUD device according to the driver's facial image may include: adjusting the display brightness of the HUD device according to the grayscale of the driver's facial image and the brightness of the display image projected by the HUD device on the windshield.

[0036] In some embodiments, adjusting the display brightness of the HUD device according to the driver's facial image may include: adjusting the display brightness of the HUD device according to the grayscale of the driver's facial image and the grayscale of the P-light image obtained by the image acquisition method.

[0037] In some embodiments, controlling the output of the HUD device based on the driver's facial image may include: controlling at least one of the following outputs of the HUD device based on the driver's facial image: adjustment of the eye box height, issuance of a fatigue warning signal, and issuance of a forward gaze warning signal.

[0038] According to yet another aspect of the present disclosure, a method for determining whether to enter or exit a channel is provided, comprising:

[0039] Acquire the driver's facial image by the above-mentioned image acquisition method, and obtain a first brightness representing the ambient brightness outside the front of the windshield according to the grayscale of the driver's facial image;

[0040] Acquire a P-light image by an image acquisition method, and obtain a second brightness representing the ambient brightness above the exterior of the windshield according to the grayscale of the P-light image; and

[0041] The first brightness is compared with the second brightness to determine whether the vehicle is about to enter or exit the passage.

[0042] According to the above technical solution, by receiving light in a predetermined direction facing the windshield, the light received from the driver's face can include only S-polarized light, and by polarizing and imaging the light received in the predetermined direction, an image of the driver's face corresponding to the ambient brightness in front of the outside of the windshield can be obtained. By adjusting the display brightness of the HUD device according to the ambient brightness, the adjustment can be more accurate, so that the brightness of the displayed image can better match the ambient brightness of its location, thereby obtaining a better visual experience and thereby improving driving safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The features and advantages of the embodiments of the present disclosure will become more easily understood through the following description with reference to the accompanying drawings. The drawings are not drawn to scale and some features may be enlarged or reduced to show details of specific components. In the drawings:

[0044] Figure 1 FIG. 1 is a schematic diagram showing an image acquisition device in a working state.

[0045] Figure 2 3 is a graph showing the transmittance of P-polarized light and S-polarized light when the angle β is the Brewster's angle or near the Brewster's angle.

[0046] Figure 3 is a schematic diagram showing the light received by the image acquisition device.

[0047] Figure 4 It is a schematic structural diagram of an image acquisition device according to an embodiment of the present disclosure.

[0048] Figure 5 It is a schematic structural diagram of an image acquisition device according to another embodiment of the present disclosure.

[0049] Figure 6 It is a schematic structural diagram of an image acquisition device according to another embodiment of the present disclosure.

[0050] Figure 7 The present invention is a flowchart of an image acquisition method according to an embodiment of the present invention.

[0051] Figure 8 It is a schematic structural diagram of a HUD device according to an embodiment of the present disclosure.

[0052] Fig. 9 Schematic diagram of a HUD device in working state.

[0053] Fig.10 The present invention is a flowchart of a control method for a head-up display device according to an embodiment of the present disclosure.

[0054] Fig.11 The present invention is a flowchart of a method for adjusting the display brightness of a HUD device according to an embodiment of the present disclosure.

[0055] Fig.12 The present invention is a flowchart of a method for adjusting the display brightness of a HUD device according to another embodiment of the present invention.

[0056] Fig.13 The present invention is a flowchart of a determination method according to an embodiment of the present invention.

[0057] In the drawings, the same or corresponding technical features or components are represented by the same or corresponding reference numerals. DETAILED DESCRIPTION

[0058] The present disclosure is described in detail below with reference to the accompanying drawings by means of exemplary embodiments. It should be noted that the following detailed description of the present disclosure is only for illustrative purposes and is by no means a limitation of the present disclosure.

[0059] It should be noted that, for the sake of clarity, not all features of a specific implementation are described and illustrated in the specification and drawings. Furthermore, in order to avoid unnecessary details that obscure the technical solution that the present disclosure focuses on, only the device structure closely related to the technical solution of the present disclosure is described and illustrated in the specification and drawings, while other details that are not closely related to the technical content of the present disclosure and are known to those skilled in the art are omitted.

[0060] As mentioned earlier, since the existing HUD device adjusts its display brightness based on the rain sensor signal, and the rain sensor signal reflects the ambient brightness above the outside of the windshield, the brightness of the display image formed by the projection of the HUD device on the windshield corresponds to the ambient brightness above the outside of the windshield.

[0061] However, the area where the displayed image is located is usually located in front of the outside of the windshield. That is to say, the display brightness of the existing HUD device is not adjusted based on the ambient brightness of the location where the displayed image is located, that is, the ambient brightness in front of the outside of the windshield, but based on the ambient brightness of other locations, that is, the ambient brightness above the outside of the windshield. Therefore, when the ambient brightness above the outside of the windshield is significantly different from the ambient brightness in front of the outside of the windshield, the display brightness of the HUD device cannot be accurately adjusted.

[0062] For example, when the ambient brightness above the outside of the windshield is greater than the ambient brightness in front of the outside of the windshield, the displayed image will be adjusted to be too bright, which may cause the driver to feel dazzled and unable to see the information in the displayed image clearly; and when the ambient brightness above the outside of the windshield is less than the ambient brightness in front of the outside of the windshield, the displayed image will be adjusted to be too dark, which may cause the driver to see unclearly or even be unable to see the information in the displayed image.

[0063] In this regard, the present disclosure attempts to adjust the display brightness of the HUD device according to the ambient brightness outside the front of the windshield to match the brightness of the displayed image with the ambient brightness of its location so that the driver can clearly observe the information in the displayed image.

[0064] Furthermore, regarding the ambient brightness in front of the windshield, the inventor noticed that the ambient light in front of the windshield would shine through the windshield onto the driver's face. Therefore, the inventor attempted to determine the brightness of the ambient light by acquiring a facial image of the driver corresponding to the ambient light, and thereby accurately determine the display brightness of the HUD device.

[0065] It should be noted that, here, more precisely, the inventors attempt to obtain the grayscale of the driver's facial image and determine the brightness of the ambient light based on it. The image grayscale is related to the light brightness. Only when there is light brightness can there be grayscale information on the image, and therefore there is an image signal. It is known that the image grayscale corresponds to the light brightness one by one.

[0066] To this end, the present disclosure provides an image acquisition device for acquiring a driver's facial image. Figures 1 to 7 , the image acquisition device 10 according to an embodiment of the present disclosure is described in detail.

[0067] First refer to Figure 1 , the image acquisition device 10 receives the light S1 facing the windshield 2 in the predetermined direction A in the working state. The extended line of the predetermined direction A passes through the virtual image 201 formed by the eye ellipse 3 via the windshield 2, and the angle β between the predetermined direction A and the normal direction B of the windshield 2 at the intersection position P of the extended line and the windshield 2 is the Brewster angle or is close to the Brewster angle.

[0068] Specifically, the image acquisition device 10 in its working state or use state faces the windshield 2, more specifically, faces the inner side of the windshield 2 close to the driver, and the image acquisition device 10 is in a specific direction. For example, the image acquisition device 10 can be fixedly arranged to be in the specific direction, or can be moved to the specific direction only when working or in use, so that it can receive the light S1 from the windshield 2 in a predetermined direction A, that is, the light S1 is incident on the image acquisition device 10 along the predetermined direction A.

[0069] The predetermined direction A is a direction in which the extended line passes through the virtual image 201 and forms an angle β with the normal direction B of the windshield 2 at the intersection position P. The virtual image 201 is the light emitted by the eyellipse 3 and reflected by the windshield 2 behind it. Figure 1 The upper part of the middle is formed. Figure 1 As shown in , the eye ellipse 3 is a statistical area where the driver's eyes are located. Theoretically, the driver's eyes are located in the statistical area when observing the display image 202 formed by the HUD device projected on the windshield 2. The predetermined direction A can be determined by the intersection position P, the normal direction B and the angle β.

[0070] In the case where the driver wears sunglasses, the facial image includes the area outside the glasses, and the position of the eyes can be determined based on the image of the area outside the glasses, or based on the outline of the glasses and the facial features such as eyebrows.

[0071] Brewster's angle refers to the specific incident angle at which the reflected light becomes nearly completely polarized light when natural light is incident on the interface between two media. Figure 2 , which shows the transmittance of P polarized light and S polarized light when β=56.6°, i.e. β is the Brewster angle, and when 56.6°-10°≤β≤56.6°+10°, i.e. 46.6°≤β≤66.6°, and β ≠ 56.6°, i.e. near the Brewster angle, with a curve graph, wherein the horizontal axis represents the angle of β, and the vertical axis represents the transmittance, for example, 0.8 represents the transmittance of 80%. In addition, curve C1 represents the transmittance of P polarized light at various angles, and curve C2 represents the transmittance of S polarized light at various angles.

[0072] Can be obtained from Figure 2 It can be clearly observed that the slope of curve C1 is very small, indicating that the P polarized light has a high transmittance at each angle within the above-mentioned angle range, while the slope of curve C2 is relatively large, indicating that the transmittance of the S polarized light at each angle within the above-mentioned angle range is relatively small, and as the angle increases, the transmittance continues to decrease. From another perspective, that is, within the above-mentioned angle range, the reflectivity of the P polarized light is very small, while the reflectivity of the S polarized light is relatively large. For example, when β=46.6°, the reflectivity of the P polarized light is 0.8%, while the reflectivity of the S polarized light is 10.4%, and when β=66.6°, the reflectivity of the P polarized light is less than or equal to 2%, while the reflectivity of the S polarized light is 26%. Therefore, relative to the higher reflectivity of the S polarized light, the reflectivity of the P polarized light can be ignored. Thus, the light from the eye ellipse (i.e., the light from the driver's face) received by the image acquisition device 10 at the angle β or in the predetermined direction A can be approximately regarded as only including S polarized light.

[0073] In this case, if Figure 3 As shown in the figure, the light S1 received by the image acquisition device 10 in the predetermined direction A includes two parts, one part is the light S2 from the driver's face which is the first light of S polarized light after being reflected by the windshield 2, and the other part is the second light S3 from the top of the outside of the windshield 2 which passes through the windshield 2 and is incident on the image acquisition device 10.

[0074] Next, refer to Figure 4 and Figure 7 , the structure and working principle of the image acquisition device 10 according to the embodiment of the present disclosure are further explained.

[0075] The image acquisition device 10 includes a polarization beam splitting element 110 and an imaging module 120 .

[0076] The polarization beam splitter 110 is configured to split the received light S1 to obtain P polarized light S11 and S polarized light S12. For example, the polarization beam splitter 110 can be configured to reflect S polarized light and transmit P polarized light (eg Figure 4 ), however, it is conceivable that the polarization splitter element 110 can also be configured to reflect P polarized light and transmit S polarized light. The polarization splitter element 110 can be a reflective polarizer, a metal wire grid, or the like.

[0077] The imaging module 120 is configured to separately image the P polarized light S11 and the S polarized light S12 obtained by the polarization beam splitting element 110 to obtain a P light image Ip and an S light image Is, respectively. Figure 4 As shown in , the imaging module 120 may include two separate parts arranged on opposite sides of the polarization beam splitting element 110 to receive the P polarized light S11 and the S polarized light S12 respectively and to image them separately. However, it is conceivable that the imaging module 11 may also be an independent whole.

[0078] In this way, Figure 4 For example, when the light S1 is incident on the polarization beam splitter 110, the first light in the light S1 forms the first S polarized light reflected by the polarization beam splitter 110, and the second light in the light S1 forms the second S polarized light reflected by the polarization beam splitter 110 and the second P polarized light passing through the polarization beam splitter 110. In this case, the S polarized light S12 includes the first S polarized light and the second S polarized light, and the P polarized light S11 includes only the second P polarized light. Thus, the P light image Ip obtained by the imaging module 120 is the image of the outer top of the windshield; and the S light image Is obtained by the imaging module 120 includes the driver's facial image Iu obtained by imaging the first S polarized light and the outer top image Is' obtained by imaging the second S polarized light.

[0079] According to an embodiment of the present disclosure, the image acquisition device 10 further includes a processing module (not shown). The processing module is configured to acquire a driver's facial image Iu according to the P-light image Ip and the S-light image Is.

[0080] Specifically, the driver's facial image Iu can be expressed by the following formula:

[0081] Iu =Is-Is'

[0082] Among them, Is can be directly obtained by the imaging module 120, and for Is', since both the external upper image Ip and the external upper image Is' come from the second light, the external upper image Is' can be expressed by the following formula:

[0083] Is'=k.×Ip

[0084] Wherein, Ip can be directly obtained by the imaging module 120, k is a magnification coefficient, which can be obtained by calibration, for example, by a series of known external upper environment brightness and the corresponding external upper image Ip and external upper image Is' obtained by detection. In the case where the image includes M×N pixels, k can be a constant or an array of M×N coefficients.

[0085] Therefore, the driver's facial image Iu corresponding to the ambient light outside the front of the windshield can be obtained through the above formula.

[0086] In some embodiments, Figure 4 As shown in , the imaging module 120 may include a first camera 121a and a second camera 122a, which are respectively arranged to receive P polarized light S11 and S polarized light S12, and are respectively configured to image the P polarized light S11 and S polarized light S12.

[0087] That is, the first camera 121a is a P-light camera, and the second camera 122a is an S-light camera. The first camera 121a and the second camera 122a can be arranged on opposite sides of the polarization beam splitting element 110, respectively, to receive the P-polarized light emitted from one side of the polarization beam splitting element 110 and the S-polarized light reflected from the other side of the polarization beam splitting element 110, respectively, so as to form images as a P-light image and an S-light image, respectively.

[0088] In some embodiments, Figure 5 As shown in , the image acquisition device 10 can be a camera including a lens 130 for receiving light S1, the polarization splitter element 110 and the imaging module 120 are arranged in the camera, and the imaging module 120 includes a first sensor 121b and a second sensor 122b, the first sensor 121b and the second sensor 122b are respectively arranged to receive P polarized light S11 and S polarized light S12, and are respectively configured to image the P polarized light S11 and the S polarized light S12.

[0089] The first sensor 121b and the second sensor 122b may be, for example, a CMOS sensor, a CCD sensor, etc. Figure 4Similar to the situation in , the first sensor 121b and the second sensor 122b can be arranged on opposite sides of the polarization splitter element 110, respectively, to respectively receive the P polarized light emitted from one side of the polarization splitter element 110 and the S polarized light reflected by the other side of the polarization splitter element 110, thereby imaging as a P light image and an S light image, respectively.

[0090] By using a sensor for imaging and by integrating the sensor and the polarization splitter element into one camera, a small-volume image acquisition device 10 can be obtained, thereby saving installation space and improving its installation adaptability so that it can be installed in more locations in the vehicle.

[0091] In some embodiments, Figure 6 As shown in , the image acquisition device 10 may further include a linear polarization element 140 , which is arranged between the polarization beam splitting element 110 and the imaging module 120 on the optical path.

[0092] For example, in Figure 6 In the embodiment, the linear polarization element 140 includes a first linear polarization element 141 and a second linear polarization element 142. The first linear polarization element 141 is arranged between the polarization beam splitting element 110 and the first camera 121a on the optical path, and the second linear polarization element 142 is arranged between the polarization beam splitting element 110 and the second camera 122a on the optical path. Thus, the polarization degrees of the P polarized light S11 and the S polarized light S12 can be increased by the first linear polarization element 141 and the second linear polarization element 142, respectively, and the light crosstalk caused by the polarization beam splitting element 110 reflecting part of the P polarized light and transmitting part of the S polarized light is reduced, thereby improving the imaging quality.

[0093] It is conceivable that the linear polarization element 140 may also be disposed only between the polarization beam splitting element 110 and the first camera 121 a , or only between the polarization beam splitting element 110 and the second camera 122 a on the optical path.

[0094] When the driver's facial image Iu corresponding to the ambient light outside the windshield can be acquired by the image acquisition device 10, as mentioned earlier, the brightness of the ambient light can be determined based on the grayscale of the driver's facial image Iu, and thus the display brightness of the HUD device can be determined.

[0095] To this end, the present disclosure provides a HUD device. Figures 8 to 13 , the HUD device 1 according to an embodiment of the present disclosure is described in detail.

[0096] First refer to Figure 8 and Fig. 9The HUD device 1 can be installed on a dashboard 4 of a vehicle, and includes an image generating unit 20 , a reflective element 30 and an image acquiring device 10 .

[0097] The image generating unit 20 is configured to emit an image light S4. The reflective element 30, such as a so-called large reflector, is configured to project the image light S4 incident thereon onto the windshield 2 to form a display image 202. The image acquisition device 10 is configured as described above to acquire the driver's facial image Iu. It is conceivable that other reflective elements may be provided on the optical path between the image generating unit 20 and the reflective element 30, for example, Figure 8 and Fig. 9 The reflective element 40 is shown in FIG.

[0098] The HUD device 1 further includes a protective cover 50 as the outermost side of the HUD device 1, and the image acquisition device 10 can be as follows: Fig. 9 In this way, it is possible to avoid placing the image acquisition device 10 at other locations in the vehicle, such as the A-pillar, the steering wheel, etc., which not only saves space but also does not affect the aesthetics of the interior of the vehicle. The protective cover 50 can be, for example, a dustproof plate (such as Figure 8 ). A hole may be opened in the protective cover 50 so that the image acquisition device 10 disposed inside the protective cover 50 receives the light S1. It is conceivable that the image acquisition device 10 may also be disposed outside the protective cover 50 of the HUD device 1.

[0099] According to an embodiment of the present disclosure, the HUD device 1 further includes a processing unit (not shown). The processing unit is configured to adjust the display brightness of the HUD device according to the grayscale of the driver's facial image Iu.

[0100] Specifically, refer to Fig.11 First, the ambient brightness L1 outside the front of the windshield 2 can be obtained by the following formula:

[0101] L1 = J1 × Iu

[0102] Wherein, Iu can be obtained by the image acquisition device 10, and J1 is a magnification factor, which can also be obtained by calibration. Then, the display brightness of the HUD device can be adjusted according to the ambient brightness L1 outside the front of the windshield 2.

[0103] Since the position corresponding to the ambient brightness L1 is the outside front of the windshield 2, it corresponds to the position of the display image 202 formed by the HUD device 1 projected onto the windshield 2. Therefore, the HUD device 1 that adjusts the display brightness according to the grayscale of the driver's facial image Iu has a higher adjustment accuracy, so that the brightness of the display image 202 can better match the ambient brightness of its location, thereby obtaining a better visual experience and thereby improving driving safety.

[0104] Further, it has been noted that when the HUD device 1 projects image light onto the windshield 2 to form a display image 202, the image light will be reflected by the windshield 2 and illuminate the driver's face, thereby making the driver's facial image Iu acquired by the image acquisition device 10 brighter than the driver's facial image corresponding to the ambient light outside the windshield, that is, the grayscale value is higher.

[0105] In order to obtain an actual driver's facial image corresponding to the ambient light outside the windshield in this case so that the adjustment of the display brightness is more accurate, in some embodiments, the processing unit can be configured to adjust the display brightness of the HUD device according to the grayscale of the driver's facial image Iu and the brightness of the display image 202.

[0106] Specifically, the image light S4 reflected by the windshield 2 and irradiated to the driver's face will be along the extension line ( Fig. 9 The display image 202 is formed as a virtual image in front of the outside of the windshield 2 (shown by a dotted line in FIG. 1 ), so the influence of the image light on the actual driver's facial image can be represented by the brightness L0' of the display image 202. Therefore, the ambient brightness L1 in front of the outside of the windshield 2 can be obtained by the following formula:

[0107] L1 = J1×(Iu-J2×L0')

[0108] Among them, similar to what has been discussed before, Iu can be obtained by the image acquisition device 10, L0' can be obtained, for example, according to the display brightness setting data of the HUD device, or according to other currently known methods, and J1 and J2 are multiplication coefficients, which will not be repeated here. Thus, the ambient brightness L1 outside the front of the windshield 2 can be obtained, and then the display brightness of the HUD device 1 can be adjusted according to the ambient brightness L1. In this way, the HUD device 1 can adjust the display brightness with higher accuracy, thereby further improving driving safety.

[0109] In addition, when entering or exiting a passage such as a tunnel, culvert, or bridge hole, due to the large difference in ambient brightness inside and outside the passage, for example, when the vehicle enters a tunnel, the ambient brightness in front of the windshield is low, usually showing a dark environment, while the ambient brightness above the windshield is high, such as showing a bright environment during the day. The driver's visual experience when observing the displayed image at the time of entering or exiting is not only affected by the ambient brightness directly in front of the vehicle, but also to a certain extent by the ambient brightness above the vehicle. In this case, it is necessary to determine whether the vehicle is about to enter or exit the passage, so as to adjust the display brightness of the HUD device 1 according to the determination result, so that the driver can obtain a better visual experience and improve driving safety.

[0110] In this regard, in some embodiments, while referring to Fig.12 , the processing unit can be configured to adjust the display brightness of the HUD device 1 according to the grayscale of the driver's facial image Iu and the grayscale of the P-light image Ip.

[0111] Specifically, the first brightness representing the ambient brightness L1 in front of the outside of the windshield 2 can be obtained according to the grayscale of the driver's facial image Iu, and the second brightness representing the ambient brightness L2 above the outside of the windshield 2 can be obtained according to the grayscale of the P-light image Ip, and by comparing the first brightness L1 with the second brightness L2, it can be determined whether the vehicle is about to enter or exit the channel.

[0112] It is conceivable that the ratio coefficient A1 of L2 and L1 is used for judgment. For example, when L2 is greater than L1, so that A1 is greater than a threshold, it is judged that the vehicle is about to enter the channel; and when L2 is less than L1, so that A1 is less than a threshold, it is judged that the vehicle is about to leave the channel.

[0113] It is also conceivable that the judgment is made based on the change rate of A1. For example, when A1 increases rapidly, it is judged that the vehicle is about to enter the passage; and when A1 decreases rapidly, it is judged that the vehicle is about to leave the passage.

[0114] It is also conceivable that the judgment is made based on the change rate of L1 and L2. For example, when L1 changes rapidly and becomes smaller, and L2 remains basically unchanged, it is judged that the vehicle is about to enter the channel; and when L1 changes rapidly and becomes larger, and L2 remains basically unchanged, it is judged that the vehicle is about to leave the channel.

[0115] After determining whether the vehicle enters or exits the passage, the processing unit may adjust the display brightness of the HUD device 1 according to a brightness adjustment strategy for the corresponding vehicle type, for example.

[0116] In addition, for the driver's facial image acquired by the image acquisition device 10, in addition to adjusting the display brightness of the HUD device 1 according to the grayscale of the driver's facial image, the processing unit can also be configured to control other outputs of the HUD device 1 according to the driver's facial image.

[0117] In this regard, in some embodiments, the processing unit may be configured to determine the size of the driver's eye pupils based on the driver's facial image, and adjust the display brightness of the HUD device 1 accordingly.

[0118] Furthermore, in some embodiments, the processing unit may be configured to determine the position of the driver's eyes based on the driver's facial image and adjust the eye box height accordingly.

[0119] In some embodiments, the processing unit may also be configured to determine the state of the driver's eyes based on the driver's facial image, and determine whether to issue a fatigue warning signal accordingly. The fatigue warning signal may be, for example, a picture or video signal displayed in the display image, or may be a sound signal.

[0120] In some embodiments, the processing unit may also be configured to determine whether the driver's eyes are looking forward based on the driver's facial image, and determine whether to send a forward gaze warning signal accordingly. Similarly, the forward gaze warning signal may be, for example, a picture or video signal displayed in the display image, or may be a sound signal.

[0121] According to another aspect of the present disclosure, referring to Figure 7 , and also provides an image acquisition method for acquiring a driver's facial image. The image acquisition method comprises:

[0122] Receive light in a predetermined direction facing the windshield, wherein an extension line of the predetermined direction passes through a virtual image formed by the eye ellipse through the windshield and an angle between the predetermined direction and a normal direction of the windshield at an intersection of the extension line and the windshield is a Brewster angle or is near the Brewster angle;

[0123] Splitting the received light to obtain P-polarized light and S-polarized light;

[0124] Separately imaging the P-polarized light and the S-polarized light to obtain a P-light image and an S-light image, respectively; and

[0125] The driver's facial image is acquired based on the P-light image and the S-light image.

[0126] According to another aspect of the present disclosure, referring to Fig.10, a control method for a HUD device is provided. The control method includes controlling the output of the HUD device according to a driver's facial image, wherein the driver's facial image is a driver's facial image acquired according to the above-mentioned image acquisition method.

[0127] In some embodiments, controlling the output of the HUD device according to the driver's facial image includes: adjusting the display brightness of the HUD device according to the driver's facial image.

[0128] In some embodiments, in conjunction with reference Fig.11 , adjusting the display brightness of the HUD device according to the driver's facial image includes: adjusting the display brightness of the HUD device according to the grayscale of the driver's facial image.

[0129] In some embodiments, adjusting the display brightness of the HUD device according to the driver's facial image includes: adjusting the display brightness of the HUD device according to the grayscale of the driver's facial image and the brightness of the display image projected by the HUD device on the windshield.

[0130] In some embodiments, in conjunction with reference Fig.12 , adjusting the display brightness of the HUD device according to the driver's facial image includes: adjusting the display brightness of the HUD device according to the grayscale of the driver's facial image and the grayscale of the P-light image obtained by the image acquisition method.

[0131] In some embodiments, controlling the output of the HUD device based on the driver's facial image includes: controlling at least one of the following outputs of the HUD device based on the driver's facial image: adjustment of the eye box height, issuance of a fatigue warning signal, and issuance of a forward gaze warning signal.

[0132] According to another aspect of the present disclosure, referring to Fig.13 , provides a method for judging whether a vehicle is entering or exiting a channel. The judgment method includes:

[0133] Acquire the driver's facial image by the above-mentioned image acquisition method, and obtain a first brightness representing the ambient brightness outside the front of the windshield according to the grayscale of the driver's facial image;

[0134] Acquire a P-light image by an image acquisition method, and obtain a second brightness representing the ambient brightness above the exterior of the windshield according to the grayscale of the P-light image; and

[0135] The first brightness is compared with the second brightness to determine whether the vehicle is about to enter or exit the passage.

[0136] In the present disclosure, the terms "first", "second", etc. are used only for the purpose of convenience of description and should not be regarded as limiting. In addition, although the present disclosure has been described with reference to exemplary embodiments, it should be understood that the present disclosure is not limited to the specific embodiments described and shown in detail herein. Those skilled in the art may make various changes to the exemplary embodiments without departing from the scope defined by the claims of the present disclosure.

[0137] The features mentioned and / or shown in the above description of the exemplary embodiments of the present disclosure may be combined in the same or similar manner into one or more other embodiments, combined with the features in other embodiments or substituted for the corresponding features in other embodiments. The technical solutions obtained by these combinations or substitutions shall also be deemed to be included in the protection scope of the present disclosure.

Claims

1. An image acquisition device, characterized in that: The image acquisition device receives light in a predetermined direction facing the windshield in a working state, wherein an extension line of the predetermined direction passes through a virtual image formed by the eye ellipse through the windshield, and an angle between the predetermined direction and a normal direction of the windshield at an intersection of the extension line and the windshield is within a range of greater than or equal to Brewster's angle minus 10° to less than or equal to Brewster's angle plus 10°, and the image acquisition device comprises: a polarization splitting element configured to split the received light to obtain P-polarized light and S-polarized light; an imaging module configured to separately image the P-polarized light and the S-polarized light to obtain a P-light image and an S-light image, respectively; and The processing module is configured to obtain a driver's facial image based on the P-light image and the S-light image.

2. The image acquisition device according to claim 1, characterized in that: The angle is in the range of 46.6° to 66.6°.

3. The image acquisition device according to claim 1, characterized in that: The imaging module includes a first camera arranged to receive the P-polarized light and configured to image the P-polarized light, and a second camera arranged to receive the S-polarized light and configured to image the S-polarized light.

4. The image acquisition device according to claim 1, characterized in that: The image acquisition device is a camera, which includes a lens for receiving the light, the polarization splitting element and the imaging module are arranged in the camera, and the imaging module includes a first sensor and a second sensor, the first sensor is arranged to receive the P polarized light and configured to image the P polarized light, and the second sensor is arranged to receive the S polarized light and configured to image the S polarized light.

5. The image acquisition device according to claim 3 or 4, characterized in that: It also includes a linear polarization element, which is arranged between the polarization beam splitting element and the imaging module on the optical path.

6. A head-up display device, characterized in that: include: An image generating unit configured to emit image light; a reflective element configured to project the image light incident thereon onto the windshield to form a display image; The image acquisition device according to any one of claims 1 to 5; as well as The processing unit is configured to control the output of the head-up display device according to the driver's facial image acquired by the image acquisition device.

7. The head-up display device according to claim 6, characterized in that: It also includes a protective cover as the outermost side of the head-up display device, and the image acquisition device is arranged on the inner side of the protective cover.

8. The head-up display device according to claim 6, characterized in that: The processing unit is configured to adjust the display brightness of the head-up display device according to the driver's facial image.

9. The head-up display device according to claim 8, characterized in that: The processing unit is configured to adjust the display brightness of the head-up display device according to the grayscale of the driver's facial image, or to adjust the display brightness of the head-up display device according to the grayscale of the driver's facial image and the brightness of the display image, or to adjust the display brightness of the head-up display device according to the grayscale of the driver's facial image and the grayscale of the P-light image.

10. An image acquisition method, characterized in that: include: Receive light in a predetermined direction facing the windshield, wherein an extension line of the predetermined direction passes through a virtual image formed by the eye ellipse through the windshield, and an angle between the predetermined direction and a normal direction of the windshield at an intersection of the extension line and the windshield is within a range of greater than or equal to Brewster's angle minus 10° to less than or equal to Brewster's angle plus 10°; Splitting the received light to obtain P-polarized light and S-polarized light; Performing separate imaging on the P polarized light and the S polarized light to obtain a P light image and an S light image, respectively; and A driver's facial image is acquired according to the P-light image and the S-light image.

11. A control method for a head-up display device, characterized in that: The method comprises controlling the output of the head-up display device according to the driver's facial image, wherein the driver's facial image is the driver's facial image acquired according to the image acquisition method according to claim 10.

12. The control method for a head-up display device according to claim 11, characterized in that: The controlling the output of the head-up display device according to the driver's facial image comprises: The display brightness of the head-up display device is adjusted according to the driver's facial image.

13. The control method for a head-up display device according to claim 12, characterized in that: The adjusting the display brightness of the head-up display device according to the driver's facial image includes: adjusting the display brightness of the head-up display device according to the grayscale of the driver's facial image, or adjusting the display brightness of the head-up display device according to the grayscale of the driver's facial image and the brightness of the display image projected by the head-up display device on the windshield, or adjusting the display brightness of the head-up display device according to the grayscale of the driver's facial image and the grayscale of the P-light image obtained by the image acquisition method.

14. A method for judging entering and exiting a channel, characterized in that: include: Acquire the driver's facial image by the image acquisition method according to claim 10, and obtain a first brightness representing the ambient brightness in front of the windshield according to the grayscale of the driver's facial image; Acquire the P-light image by the image acquisition method, and obtain a second brightness representing the ambient brightness above the exterior of the windshield according to the grayscale of the P-light image; as well as The first brightness is compared with the second brightness to determine whether the vehicle is about to enter or exit a passage.

Images