Patent Publication Number: US-2019179587-A1

Title: Optical imaging device with backup display

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to an optical imaging device, and particularly to an optical imaging device with backup display. 
     BACKGROUND OF THE INVENTION 
     The applications of head-up displays (HUD) are extended form airplanes to automobiles. To enhance driving safety, the simple information provided by HUD is unable to meet car drivers&#39; requirements. Consequently, the augmented reality (AR) for HUD has been developed, in which the car status information to be provided to the driver is overlapped with the road status as seen by the driver. The car status information includes insufficient safety distance, lane departure, lane change notification and is substantial to improving driving safety. 
     The modern trend is to gradually replace the car dashboard by HUD. Unfortunately, the quality and stability of car dashboard are extremely high. Contrarily, an HUD includes optical, mechanical, and power-consuming elements, for example, the China Patent Applications No. 201410453217.8 and No. 201380073633.9 and the U.S. Pat. No. 9,030,748, and hence making the stability of an HUD lower than the stability of a car dashboard. During the design process for replacing the car dashboard and becoming an important and the only safety information device, not only should the performance of the HUD be considered, but how to provide the driver with the basic car status information when the device fails is also extremely important for complying with international standards such as ISO26262 (Road Vehicles—Functional Safety). 
     Accordingly, the present invention provides an optical imaging device with backup display for solving the above technical shortcomings. The optical imaging device with backup display comprises a backup display module. Thereby, when the main display module is abnormal, the backup display module still can display the car status information. 
     SUMMARY 
     An objective of the present invention is to provide an optical imaging device with backup display, which comprises a backup display module for displaying the real image. When the main display module is abnormal, the backup display module still can display the car status information. 
     The present invention relates to an optical imaging device with backup display, which comprises a housing, a main display module, and a backup display module. The main display module and the backup display module are disposed in the housing. The main display module projects a first image to be a virtual image. The backup display module displays a second image, which is a real image. Thereby, when the main display module is abnormal, the backup display module still can display the car status information. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  shows a stereoscopic diagram of the optical imaging device according to an embodiment of the present invention; 
         FIG. 1B  shows a cross-sectional view of the optical imaging device according to an embodiment of the present invention; 
         FIG. 2  shows a control block diagram of the optical imaging device according to an embodiment of the present invention; 
         FIG. 3A  shows a schematic diagram of the optical imaging device projecting images according to an embodiment of the present invention; 
         FIG. 3B  shows a schematic diagram of the optical imaging device projecting images to the visual region according to an embodiment of the present invention; 
         FIG. 4A  shows a stereoscopic diagram of the optical imaging device according to another embodiment of the present invention; and 
         FIG. 4B  shows a cross-sectional view of the optical imaging device according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the specifications and subsequent claims, certain words are used for representing specific devices. A person having ordinary skill in the art should know that hardware manufacturers might use different nouns to call the same device. In the specifications and subsequent claims, the differences in names are not used for distinguishing devices. Instead, the differences in functions are the guidelines for distinguishing. In the whole specifications and subsequent claims, the word “comprising” is an open language and should be explained as “comprising but not limited to”. Besides, the word “couple” includes any direct and indirect electrical connection. Thereby, if the description is that a first device is coupled to a second device, it means that the first device is connected electrically to the second device directly, or the first device is connected electrically to the second device via other device or connecting means indirectly. 
     Please refer to  FIG. 1A  and  FIG. 1B , which show a stereoscopic diagram and a cross-sectional view of the optical imaging device according to an embodiment of the present invention. As shown in  FIG. 1A  and  FIG. 1B , the optical imaging device  10  according to the present embodiment comprises a housing  14 , a main display module  16 , and a backup display module  20 . The housing  14  according to the present embodiment includes a display window  142 . The main display module  16  according to the present embodiment includes a reflection mirror  162 , an optical projection element  164 , and a main display unit  166 . The backup display module  20  is different from the main display module  16 . The backup display module  20  displays real images directly, instead of reflecting or projecting images through optical elements. According to an embodiment of the present invention, the backup display module  20  may be a segment display, a dot-matrix display, or a simple liquid crystal display with backlight. 
     Please refer again to  FIG. 1A  and  FIG. 1B . The main display module  16  is disposed in the housing  14  for projecting a first image IMG 1 , as shown in  FIG. 3A . The reflection mirror  162 , the optical projection element  164 , and the main display unit  166  are all disposed in the housing  14 . The main display unit  166  displays the first image IMG 1 ; the reflection mirror  162  reflects the first image IMG 1 . Because the optical projection element  164  is located on the reflection path of the reflection mirror  162 , the reflection mirror  162  reflects the first image IMG 1  to the optical projection element  164  before the optical projection element  164  projects the first image IMG 1 . According to an embodiment of the present embodiment, the optical projection element  164  may be a spherical mirror, which may magnify the first image IMG 1  reflected by the reflection mirror  162 . Hence, a magnified reflected first image IMG 1  will be provided. Alternatively, the optical projection element  164  may be a plane mirror, which may reflect the first image IMG 1  directly. Because the first image IMG 1  is reflected by the reflection mirror  162  and projected by the optical projection element  164 , the main display module  16  projects the first image IMG 1  to be a virtual image. 
     The backup display module  20  according to the present embodiment is disposed on one side of the display window  142  of the housing  14 . It is also located on one side of the main display module  16 . The backup display module  20  displays a second image IMG 2 , which is a real image, as shown in  FIG. 3A . The second image IMG 2  is not reflected by optical elements. 
     Please refer to  FIG. 2 , which shows a control block diagram of the optical imaging device according to an embodiment of the present invention. As shown in the figure, the main display module  16  may further include a backlight unit  167 , which is disposed behind the main display unit  166  for providing backlight to the main display unit  166 . In addition, the main display module  16  may further include a rotation mechanism  168 , which is used for rotating the optical projection element  164  for adjusting the angle of projecting the first image IMG 1 . The optical imaging device  10  according to the present invention may further comprise a control circuit  30 , which is coupled to the main display module  16  and the backup display module  20  for controlling the main display module  16  to project the first image IMG 1  and for controlling the backup display module  20  to display the second image IMG 2 . 
     The control circuit  30  includes a first control unit  32  and a second control unit  34 . The first control unit  32  is coupled to the main display unit  166 , the backlight unit  167 , and the rotation mechanism  168  of the main display module  16  for controlling the main display unit  166  to display the first image IMG 1 , the backlight unit  167  to provide backlight, and the rotation mechanism  168  to rotate the optical projection element  164 . Thereby, the first control unit  166  may control the main display module  16  to project the first image IMG 1 . The second control unit  34  is coupled to the backup display module  20  and controls the backup display module  20  to display the second image IMG 2 . 
     Moreover, the first control unit  32  and the second control unit  34  are coupled to a bus BUS of the car. The bus BUS is coupled to the various detectors of the car, such as the engine temperature sensor and the engine tachometer. The status information produced by the detectors detecting the car status may be transmitted to the bus BUS. Thereby, the first control unit  32  and the second control unit  34  may extract the car status information from the bus BUS. Then the first control unit  32  may transmit the car status information to the main display unit  166 , so that the main display unit  166  may display the first image IMG 1  according to the car information. In other words, the first image IMG 1  includes the car status information. In addition, the second control unit  34  may control the backup display module  20  to display the second image IMG 2  according to the car status information. According to the above description, the control circuit  30  may control the main display module  16  to display and project the first image IMG 1  to be the virtual image and the backup display module  20  to display the second image IMG 2  according to the car status information. 
     According to an embodiment of the present invention, the second control unit  34  is coupled to the first control unit  32 . The second control unit  34  may transmit the car status information to the first control unit  32 . In addition, the first control unit  32  and the second control unit  34  may be integrated to be a single chip. 
     Please refer again to  FIG. 2 . The first control unit  32  may detect the states of the rotation mechanism  168 , the backlight unit  167 , and the main display unit  166 . If the first control unit  32  judges that the rotation mechanism  168 , the backlight unit  167 , or the main display unit  166  is in an abnormal state, it notifies the second control unit  34 , for example, transmitting an abnormal signal to the second control unit  34 , for driving the second control unit  34  to control the backup display module  20  to display the second image IMG 2 . Besides, the second control unit  34  will also detect the state of the first control unit  32 . If the second control unit  34  judges that the first control unit  32  is in an abnormal state, it controls the backup display module  20  to display the second image IMG 2 . It means that the second control unit  34  controls the backup display module  20  to display the second image IMG 2  according to the states of the main display module  16  and the first control unit  32 . 
     Furthermore, the second control unit  34  may be coupled to the rotation mechanism  168 , the backlight unit  167 , and the main display unit  166  as well for detecting their states. When their states are abnormal, the second control unit  34  may control the backup display module  20  to display the second image IMG 2 . As shown in  FIG. 1A , the backup display module  20  may display the basic car status information, such as the fuel quantity, the speed, and the temperature. It means that when the main display module  16  is in an abnormal state, the second image IMG 2  displayed by the backup display module  20  includes at least a portion of the car status information for the driver for ensuring driving safety, so that the driver can, for example, drive to the vehicle maintenance depot for examining the main display module  16 . The backup display module  20  is a simple display module, making its architectural complexity lower than that of the main display module  16 . Besides, the power consumption of the backup display module  20  is lower than the power consumption of the main display module  16 . Consequently, the stability of the backup display module  20  is higher than the stability of the main display module  16 . 
     Please refer to  FIG. 3A  and  FIG. 3B . The optical imaging device  10  according to the present invention projects the first image IMG 1  or displays the second image IMG 2 . The first image IMG 1  or the second image IMG 2  is reflected by the windshield W to the human eye. The first image IMG  1  projected by theoptical imaging device  10  or the second image IMG 2  displayed by the optical imaging device  10  is the inverted image. The first image IMG for the second image IMG 2  becomes the positive image after reflection by the windshield W, and is reflected by the windshield W to the human eye. The main display unit  166  displays the first image IMG  1 , which is the inverted image. The first image IMG  1  is reflected by the reflection mirror  162  to the optical projection element  164 . Then the optical projection element  164  projects the first image light LG 1  including the first image IMG 1  toward the display window  142 . In the backup display module  20 , the second image light LG 2  including the second image IMG 2  is displayed directly, that the second image light LG 2  is not reflected by optical elements. 
     As shown in  FIG. 3A  and  FIG. 3B , the main display unit  166  of the optical imaging device  10  according to the present invention generates the first image IMG 1 , which is reflected by the reflection mirror  162  to the optical projection element  164 . The optical projection element  164  projects the first image IMG 1  according to a visual optical path P 1 . After the first image IMG 1  is reflected by the windshield W, a reflection optical path P 2  is formed, corresponding to the visual optical path P 1 . According to an embodiment of the present invention, the second image IMG 2  is located on one side of the first image IMG 1 . For example, the second image IMG 2  is located below or on both sides of the first image IMG 1 . In addition, because the second image IMG 2  may include fewer car status information, the second image IMG 2  is smaller than the first image IMG 1 , making the display region corresponding to the second image IMG 2  smaller than the display region of the first image IMG 1 . 
     Please refer to  FIG. 4A  and  FIG. 4B , which show a stereoscopic diagram and a cross-sectional view of the optical imaging device according to another embodiment of the present invention. The difference between the present embodiment and the previous one is that the backup display module  20  according to the previous embodiment (as shown in  FIGS. 1A and 1B ) is located outside the housing  14 . Namely, the backup display module  20  is located outside the display window  142 . Contrarily, the backup display module  20  according to  FIGS. 4A and 4B  is located inside the housing  14 . In other words, the backup display module  20  is located inside the display window  142 . The rest elements are identical to the description according to the previous embodiment. 
     Please refer again to  FIGS. 1A, 3B, and 4A . Because the backup display module  20  also projects the second image IMG 2  to the windshield W, the text displayed by the backup display module  20  is upside down, so that the second image IMG 2  can be inverted to positive image after reflection by the windshield W. Likewise, the first image IMG 1  projected by the main display module  16  is also upside down, so that the first image IMG 1  can be inverted to positive image after reflection by the windshield W. 
     To sum up, the present invention provides an optical imaging device with backup display. When the main display module is abnormal, the backup display module still can display images to a driver&#39;s visual region for providing the car status information and hence ensuring the driving safety. 
     Accordingly, the present invention conforms to the legal requirements owing to its novelty, nonobviousness, and utility. However, the foregoing description is only embodiments of the present invention, not used to limit the scope and range of the present invention. Those equivalent changes or modifications made according to the shape, structure, feature, or spirit described in the claims of the present invention are included in the appended claims of the present invention.