Patent Publication Number: US-2021170946-A1

Title: Vehicle surrounding image display device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2019-223069 filed on Dec. 10, 2019, incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a vehicle surrounding image display device. 
     2. Description of Related Art 
     The technique described in Japanese Unexamined Patent Application Publication No. 2012-170127 (JP 2012-170127 A) displays the video behind the vehicle in the horizontal central display area of the video display means at a video size corresponding to the image reflected on the inner mirror. At the same time, this technique displays the video behind and to the right of the vehicle and the video behind and to the left of the vehicle in the display areas outside of the central display area as an image compressed higher than the video behind the vehicle. 
     SUMMARY 
     For an object that is located at a predetermined distance or more from the vehicle, the display size of the object on the display image has a large effect on the feeling of a sense of distance to the object. On the other hand, for an object that is within a predetermined distance from the vehicle, the relative position between the vehicle and the object on the display image has a large effect on the feeling of a sense of distance to the object. The technique described in JP 2012-170127 A does not treat the feeling of a sense of distance to an object but only switches the display between the central display area and the outer display area regardless of the distance between the vehicle and an object. Therefore, there is room for improvement in allowing an occupant of the vehicle to feel a correct sense of distance between the vehicle and an object from the displayed image. 
     The present disclosure provides a vehicle surrounding image display device that allows an occupant to feel a correct sense of distance to an object existing around the vehicle. 
     A vehicle surrounding image display device includes a display control unit is configured to cause an image display unit to display a first image in a specific area, the first image being one of captured images and corresponding to the specific area, the captured images being generated by a capturing unit by capturing an area behind a vehicle and an area behind and to sides of the vehicle, the specific area being an area within a range of a first length extending in both directions outward from a horizontal central part of a display area of the image display unit and within a range of a second length extending vertically downward from an upper end of the display area; and cause the image display unit to display a second image in an area outside of the specific area of the display area, the second image being one of the captured images and corresponding to the area outside of the specific area, the second image being compressed higher than the first image. 
     According to the aspect described above, the area included in the display area of the image display unit and corresponding to an object that is located at a relatively large distance from the vehicle is set as the specific area. In addition, the second image corresponding to an object that is located at a relatively small distance from the vehicle and displayed outside of the specific area is compressed higher than the first image displayed in the specific area. In this way, the vehicle surrounding image display device according to the aspect described above switches the display of images between the two areas, the specific area and the area outside of the specific area, where the distance between the vehicle and an object differs between these two areas, allowing an occupant to feel a more correct sense of distance to an object around the vehicle. 
     In the aspect described above, the first image may be an image captured in a capturing range located at a predetermined distance or more from the vehicle; and the second image may be an image captured in a capturing range within the predetermined distance from the vehicle. 
     According to the configuration described above, since the capturing range of the first image displayed in the specific area is a range that is located at the predetermined distance or more from the vehicle, an occupant can feel a sense of distance to an object that is the predetermined distance or more from the vehicle. In addition, according to the configuration described above, since the capturing range of the second image displayed outside of the specific area is a range that is within the predetermined distance from the vehicle, an occupant can feel a sense of distance to an object that is less than the predetermined distance from the vehicle. 
     In the aspect described above, a compression ratio of the second image may be increased as a distance from a boundary of the specific area is increased. 
     According to the configuration described above, as compared with the case in which the compression ratio of the second image is not increased, the images in a wider capturing range can be displayed on the image display unit. 
     In the aspect described above, the display control unit may be configured to cause the image display unit to display the first image in such a way that the first image is displayed at a compression-decompression ratio corresponding to a size of an optical reflection image behind the vehicle and behind and to the sides of the vehicle which is visually recognized by an occupant of the vehicle, the optical reflection image being an image reflected on an optical inner rearview mirror of the vehicle. 
     According to the configuration described above, the first image can be displayed so that an occupant can feel a more correct sense of distance to an object included in the first image. 
     In the aspect described above, the display control unit may include a simulated image generation unit configured to generate a simulated image simulating a body of the vehicle and a superimposed-image display unit configured to cause the image display unit to display the simulated image, which is generated by the simulated image generation unit, by superimposing the simulated image on the first image and the second image. 
     According to the configuration described above, the positional relationship between the images of objects, which are included in the first image and the second image, and the body of the vehicle, which is included in the simulated image, allows an occupant to feel a more correct sense of distance to the objects included in the first image and the second image. 
     The present disclosure has an effect that an occupant can feel a correct sense of distance to an object around a vehicle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features, advantages, and technical and industrial significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like signs denote like elements, and wherein: 
         FIG. 1  is a block diagram showing a schematic configuration of a vehicle surrounding image display system; 
         FIG. 2  is an image diagram showing the capturing range of a camera in a configuration where one camera is provided; 
         FIG. 3  is a functional block diagram of a display ECU; 
         FIG. 4  is a diagram showing an example of a compression ratio map; 
         FIG. 5  is a flowchart showing display processing; 
         FIG. 6  is an image diagram showing an example of a captured image; 
         FIG. 7  is an image diagram showing an example of an image having a converted compression ratio; 
         FIG. 8  is an image diagram showing an example of an image displayed on a display; 
         FIG. 9  is a block diagram showing another example of a schematic configuration of the vehicle surrounding image display system; and 
         FIG. 10  is an image diagram showing the capturing range of cameras in a configuration in which three cameras are provided. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     An example of an embodiment of the present disclosure will be described in detail below with reference to the drawings. A vehicle surrounding image display system  10  shown in  FIG. 1  includes one camera  12 , a display electronic control unit (ECU)  14 , and a display  16 . The camera  12  and the display  16  are connected to the display ECU  14 . As shown in  FIG. 2 , the camera  12 , with a relatively wide capturing range (capturing range  20 ), is attached to the rear of a vehicle  18  so that the image behind the vehicle  18  and behind and to the sides of the vehicle  18  can be captured. The camera  12  is an example of a capturing unit. 
     The display  16  is provided at a position spaced above the central part of the instrument panel of the vehicle  18  in the upward direction of the vehicle  18 . As an example, a specific area  42  is set in the display area  16 A of the display  16  as shown in  FIG. 7 . The specific area is an area within a range of the first length W extending in both directions outward from the horizontal central part of the display area  16 A and within a range of the second length H extending vertically downward from the upper end of the display area  16 A. In a vehicle provided with an optical inner rear-view mirror, the specific area  42  corresponds to an area where the image of an object from a predetermined distance L (for example, 5 m, 10 m, 15 m etc.) to an infinite distance away from the vehicle is displayed. The display  16  is an example of an image display unit. 
     The display ECU  14  includes a central processing unit (CPU)  22 , a memory  24  such as a read only memory (ROM) and a random access memory (RAM), a nonvolatile storage unit  26  such as a hard disk drive (HDD) and a solid state drive (SSD), and a communication unit  28 . The CPU  22 , the memory  24 , the storage unit  26 , and the communication unit  28  are communicatively connected to each other via an internal bus  30 . 
     The storage unit  26  of the display ECU  14  stores a display program  32 . The display program  32  is read from the storage unit  26  and loaded into the memory  24 . When the display program  32 , loaded into the memory  24 , is executed by the CPU  22 , the display ECU  14  functions as a display control unit  34  that includes three functional units shown in  FIG. 3 : a conversion unit  36 , a simulated image generation unit  38 , and a superimposed-image display unit  40 . These functional units perform the display processing that will be described below. The display ECU  14  is an example of a vehicle surrounding image display device. 
     The display control unit  34  causes the display  16  to display a first image in the specific area  42  that is an area in a display area  16 A of the display  16 . The first image is an image included in the images captured by the camera  12  and corresponding to the specific area  42 . The first image is an image captured in the capturing range that is located at a predetermined distance L or more from the vehicle  18  (an image in the range from the predetermined distance L to the infinite distance) and is the image of an object that is at a position that is a predetermined distance L or more from the vehicle  18 . In this embodiment, the capturing range of the first image, which is located at a predetermined distance L or more from the vehicle  18 , is the range directly behind the vehicle and within a specific angle. 
     In addition, the display control unit  34  causes the display  16  to display a second image in an area outside of the specific area  42  of the display area  16 A of the display  16  as an image compressed higher than the first image. The second image is an image included in the captured images and corresponding to an area outside of the specific area  42 . The second image is an image captured in the capturing range that is less than a predetermined distance L from the vehicle  18  and is the image of an object that is at a position less than a predetermined distance L from the vehicle  18 . In this embodiment, the capturing range of the second image, which is less than a predetermined distance L from the vehicle  18 , is the range directly behind the vehicle and outside a specific angle. 
     More specifically, the conversion unit  36  of the display control unit  34  compresses the second image higher than the first image as described above. For example, as shown in  FIG. 4 , the conversion unit  36  compresses the first image and the second image of the captured images based on the compression ratio map that defines the relationship between a position within an image and the compression ratio of the image at that position. 
     In the compression ratio map shown in  FIG. 4 , the compression ratio of the specific area  42  (compression ratio for the first image) is set to be substantially constant. The compression ratio of the specific area  42  is set in such a way that the first image displayed in the specific area  42  is displayed at a compression ratio corresponding to the size of the optical reflection image behind the vehicle and behind and to the sides of the vehicle which is visually recognized by an occupant of the vehicle. The optical reflection image is an image reflected on the optical inner rearview mirror of the vehicle. On the other hand, in the compression ratio map shown in  FIG. 4 , the compression ratio of the area outside of the specific area  42  is set in such a way that the compression ratio of the area of outside of the specific area  42  (compression ratio for the second image) is increased as the distance from the boundary of the specific area is increased. 
     The simulated image generation unit  38  generates a simulated image simulating the body of the vehicle  18  that comes into view when an occupant views the area behind the vehicle  18  and behind and to the sides of the vehicle  18  from within the vehicle cabin of the vehicle  18 . The superimposed-image display unit  40  superimposes the simulated image, generated by the simulated image generation unit  38 , on the first image and the second image and causes the display  16  to display the resulting image. 
     Next, an operation of this embodiment will be described below. More specifically, the display processing performed by the display ECU  14  while the ignition switch of the vehicle  18  is turned on will be described with reference to  FIG. 5 . 
     In step  100  of the display processing, the conversion unit  36  acquires a captured image, captured by the camera  12 , from the camera  12 .  FIG. 6  shows an example of a captured image the conversion unit  36  acquires from the camera  12 . 
     In step  102 , the conversion unit  36  converts the compression ratio of the captured image, acquired from the camera  12 , according to the compression ratio map ( FIG. 4 ).  FIG. 7  shows an example of an image having a compression ratio converted by the conversion unit  36 . The comparison between  FIG. 7  and  FIG. 6  clearly indicates that, in the image where the compression ratio has been converted, the size of the image of the object displayed in the specific area  42  is the same while the size of the image outside of the specific area  42  is reduced (compressed). 
     In step  104 , the simulated image generation unit  38  generates a simulated image simulating the body of the vehicle  18 . The simulated image, generated by the simulated image generation unit  38 , is an image compressed according to the compression ratio map ( FIG. 4 ).  FIG. 8  shows an example of a simulated image, generated by the simulated image generation unit  38 , as a simulated image  44 . The simulated image  44  is an image in which the area corresponding to the body of the vehicle  18  is semitransparent (shaded area in the figure) and in which the area corresponding to the window of the vehicle  18  is transparent. 
     Note that a simulated image need not always be compressed in the same manner as the second image is compressed according to the compression ratio map. Instead, to prevent an unnatural distortion from being generated in a simulated image, only the image close to a window frame in the simulated image may be changed according to the scenery (second image). 
     In step  106 , the superimposed-image display unit  40  superimposes the simulated image, generated by the simulated image generation unit  38 , on the images having a compression ratio converted by the conversion unit  36  to generate a display image to be displayed by the display  16 . In step  108 , the superimposed-image display unit  40  causes the display  16  to display the display image generated in step  106 . 
     As a result, an image such as a display image  46  shown in  FIG. 8  is displayed in the display area  16 A of the display  16 . According to the knowledge obtained by the inventor of the present disclosure, for an object that is located at a predetermined distance L or more from the vehicle  18 , the display size of the object on the display image  46  has a large effect on the feeling of a sense of distance to the object. Based on this knowledge, in the specific area  42  which is included in the display image  46  and in which an object that is located at a predetermined distance L or more from the vehicle  18  is displayed as an image, the compression ratio of the image is set lower than the compression ratio of an image outside of the specific area  42 . As a result, the size of an image  48  displayed in the specific area  42  of the display image  46  (see arrows A and B in  FIG. 8 ) allows an occupant of the vehicle to feel a correct sense of distance to an object corresponding to the image  48 . 
     Furthermore, according to the knowledge obtained by the inventor of the present disclosure, for an object that is less than a predetermined distance L from the vehicle  18 , the relative position between the vehicle and the object on the display image  46  has a large effect on the feeling of a sense of distance to the object. Based on this knowledge, in the outside of the specific area  42  which is included in the display image  46  and in which an object that is less than the predetermined distance L from the vehicle  18  is displayed as an image, the compression ratio of the image is set higher than the compression ratio of the specific area  42  and, therefore, the body of the vehicle  18  displayed in a larger part of this area as the simulated image  44 . As a result, the relative position (see arrows C and D in  FIG. 8 ) between the body of the vehicle  18 , represented by the simulated image  44 , and the image  50 , displayed outside of the specific area  42  of the display image  46 , allows an occupant of the vehicle to feel a correct sense of distance to the object corresponding to the image  50 . 
     After the processing in step  108 , the processing returns to step  100  and, while the ignition switch of the vehicle  18  is turned on, steps  100  to  108  are repeated. While step  100  to step  108  are performed repeatedly, the video of the surroundings is displayed on the display  16  in which the positions and sizes of the images of objects, included in the display image  46 , change according to a change in the relative position between the vehicle  18  and objects around the vehicle  18 . 
     In this embodiment, the display control unit  34  causes the display  16  to display the first image in the specific area  42  as described above. The first image is an image included in the images captured by the camera  12  by capturing the area behind the vehicle  18  and behind and to the sides of the vehicle  18  and corresponding to the specific area  42 . The specific area  42  is an area within a range of the first length W extending in both directions outward from the horizontal central part of the display area  16 A of the display  16  and within a range of the second length H extending vertically downward from the upper end of the display area  16 A. Furthermore, the display control unit  34  causes the display  16  to display the second image included in the captured images and corresponding to the outside of the specific area  42  in an area outside of the specific area  42  of the display area  16 A as an image compressed higher than the first image. Displaying the first image and the second image as described above allows an occupant to feel a more correct sense of distance to an object around the vehicle. 
     In this embodiment, the first image is an image in the capturing range that is located at a predetermined distance L or more from the vehicle  18 , and the second image is an image captured in the capturing range that is less than a predetermined distance L from the vehicle  18 . Displaying the first image and the second image allows an occupant to feel a sense of distance to an object that is located at a predetermined distance L or more from the vehicle  18  and to feel a sense of distance to an object that is less than a predetermined distance L from the vehicle  18 . 
     In this embodiment, the display control unit  34  increases the compression ratio of the second image as the distance from the boundary of the specific area  42  increases, causing the display  16  to display images in a wider capturing range. 
     In addition, in this embodiment, the display control unit  34  causes the display  16  to display the first image in such a way that the first image is displayed at a compression/decompression ratio corresponding to the size of the optical reflection image behind the vehicle and behind and to the sides of the vehicle which is visually recognized by the driver of the vehicle. The optical reflection image is an image reflected on the optical inner rearview mirror of the vehicle. Displaying the first image in this way allows an occupant to feel a more correct sense of distance to an object included in the first image as an image. 
     Furthermore, in this embodiment, the display control unit  34  includes the simulated image generation unit  38  that generates a simulated image simulating the body of the vehicle  18  and the superimposed-image display unit  40  that causes the display  16  to display the simulated image, generated by the simulated image generation unit  38 , with the simulated image superimposed on the first image and the second image. This configuration allows an occupant to feel a more correct sense of distance to the objects included in the display image  46 , based on the positional relationship between the images of objects included in the display image  46 , such as the first image and the second image, and the body of the vehicle included in the simulated image. 
     One camera, camera  12 , is provided as the capturing unit in the configuration described above, while three cameras, cameras  54 A to  54 C, are provided as the capturing units in the configuration shown in  FIG. 9 . As shown in  FIG. 10 , the camera  54 A captures the area behind the vehicle  18  from the rear of the vehicle  18  (capturing range  56 A), the camera  54 B captures the area to the right of the vehicle  18  and behind and to the right of the vehicle  18  from the right side of the vehicle  18  (capturing range  56 B), and the camera  54 C captures the area to the left of the vehicle  18  and behind and to the left of the vehicle  18  from the left side of the vehicle  18  (capturing range  56 C). In  FIG. 9 , the display control unit  34  includes a synthesizing unit  58 . The synthesizing unit  58  synthesizes the three captured images captured by three cameras, cameras  54 A to  54 C, into one image and outputs the synthesized image to the conversion unit  36 . In this way, the capturing unit may be configured to include a plurality of cameras. 
     In the above description, the display  16  is provided at a position spaced above the central part of the instrument panel of the vehicle  18 . However, the installation position of the display  16  is not limited to the position described above. For example, the display  16  may be provided at the central part of the instrument panel of the vehicle  18 . 
     In the above description, the compression ratio of an area outside of the specific area  42  (compression ratio for the second image), defined in the compression ratio map shown in  FIG. 4 , is increased linearly as the distance from the boundary of the specific area is increased. However, the compression ratio is not limited to this definition. For example, the compression ratio of an area outside of the specific area  42  (compression ratio for the second image) may be increased curvilinearly (for example, quadratically) as the distance from the boundary of the specific area is increased.