Patent Publication Number: US-2011074954-A1

Title: Image monitoring system for vehicle

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to image monitoring systems. In particular, the present invention relates to an image monitoring system integrating multiple cameras. 
     2. Description of the Prior Art 
     With the advancement in various consumer electronic products, more and more vehicles are equipped with a small LCD panel in front of the driver&#39;s seat. This display panel can display video films, information about the multimedia system, or maps provided by navigation software. Besides these functions, some display panels can also display exterior images captured by cameras assembled at the front or rear parts of the vehicle, so as to assist the driver in knowing conditions in the vicinity of the vehicle. 
     In present electronic systems for vehicles, cameras assembled at different locations respectively transmit captured images to the central control apparatus and the display panel generally located at the front part of the vehicle. In other words, there is an independent transmission cable connected between each camera and the central control apparatus. For vehicles with limited inner spaces, the more cameras are used, the more troublesome the arrangement of transmission cables is. Correspondingly, the complexity of maintaining this system is also high. 
     SUMMARY OF THE INVENTION 
     To solve the aforementioned problem, the invention provides an image monitoring system that effectively integrates signals with hubs. 
     The image monitoring system in one embodiment according to the invention includes a plurality of image detecting modules assembled on a vehicle, a hub, a central processing module, and a display module. After being respectively processed and compressed, the video signals captured by the image detecting modules are transmitted to the hub via transmitting interfaces. The hub is used for receiving and integrating the compressed signals to generate an integrated signal. The central processing module is used for decompressing the integrated signal to at least one recovered video signal and providing the at least one recovered video signal to the display module. 
     By utilizing hubs to integrate signals from plural image detecting modules and other peripheral devices, the number of transmission cables connected to the central control apparatus and the display panel is considerably reduced. The complexity and cost of setting up of the system are both decreased. Further, the complexity of maintaining this system is lowered as well. The image monitoring system according to the invention is especially suitable for vehicles with limited inner spaces. 
     The advantage and spirit of the invention may be understood by the following recitations together with the appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE APPENDED DRAWINGS 
         FIG. 1(A) ,  FIG. 1(B) , and  FIG. 1(C)  illustrate the block diagram of the image monitoring system for vehicles in the first embodiment according to the invention. 
         FIG. 2  is the block diagram of the image monitoring system for vehicles in the second embodiment according to the invention. 
         FIG. 3(A)  and  FIG. 3(B)  illustrate the block diagram of the image monitoring system for vehicles in the third embodiment according to the invention. 
         FIG. 4  is the block diagram of the image monitoring system for vehicles in the fourth embodiment according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Please refer to  FIG. 1(A) , which illustrates the block diagram of the image monitoring system for vehicles in one embodiment according to the invention. The image monitoring system  10  includes a plurality of image detecting modules  11  (only two are presented in this figure), a hub  12 , a central processing module  13 , and a display module  14 . 
     The image detecting modules  11  can be assembled at various locations on the vehicle with high flexibility. For example, image detecting modules  11  disposed at the front or rear regions of the vehicle can be used to observe surroundings out of the vehicle. Taking passenger coaches for instance, the image detecting modules  11  disposed around drivers&#39; seat or passengers&#39; seats can be used to monitor or record the conditions of people inside the car. For boot trunks of passenger coaches or freight cars, the image detecting modules  11  can be used to monitor areas where commodities are placed. 
     As shown in  FIG. 1(A) , each of the image detecting modules  11  respectively includes an image detector  11 A, a digital image processor  11 B, an image compressor  11 C, and a transmitting interface  11 D. In the following descriptions, the condition that both the transmitting interface  11 D and the hub  12  conform to the universal serial bus (USB) standard is taking as an example. 
     The image detector  11 A is used for capturing images of an outer or inner region of the vehicle and generating a video signal. In actual applications, the image detector  11 A can be an analog image detector conforming to NTSC or PAL specifications. Alternatively, the image detector  11 A can also be a digital image detector including optical lenses and a complementary metal-oxide semiconductor (CMOS) image sensor or a charged coupled device (CCD) image sensor. 
     The digital image processor  11 B electrically connected to the image detector  11 A is used for performing a digital image processing procedure on the video signal generated by the image detector  11 A and then generates a processed signal. For instance, the digital image processor  11 B can perform an automatic exposure process on images or films generated by the image detector  11 A, so as to adjust their brightness or contrast. The digital image processor  11 B can also improve the color quality of images by processes such as white-balance correction or color correction. 
     If the image detector  11 A is a digital image detector with a CMOS or CCD image sensor, the output signal of the image detector  11 A has already been a digital signal. Hence, an analog-to-digital converter between the image detector  11 A and the digital image processor  11 B is not needed under this condition. Image distortions caused by analog-to-digital conversions can thereby be prevented. 
     The image compressor  11 C is electrically connected to the digital image processor  11 B and used for compressing the processed signal provided by the digital image processor  11 B, so as to generate a compressed signal. Practically, the image compressor  11 C can adopt compression standards such as MPEG4, H.264, MJPEG, etc., but not limited to these examples. Besides, compression standards adopted by image compressors  11 C in different image detecting modules  11  do not have to be the same. 
     The USB interface  11 D is used for transmitting the compressed signal to external devices connected to the image detecting module  11 . The USB hub  12  is responsible for receiving and integrating the compressed signals from the image detecting modules  11 , so as to generate an integrated signal. 
     According to the invention, the resolution and compression-ratio adopted by the image compressors  11 C can be related to transmitting limitations of the USB hub  12 . Taking USB 2.0 standard as an example, each USB hub can receive signals from at most four USB devices, and the maximum data amount transmitted in a USB cable is 480 Mb/s. Based on this limitation, the data amount outputted by the image detecting modules  11  and the compression-ratio adopted by the image compressors  11 C can be determined. 
     The central processing module  13  can include a decompressor conforming to MJPEG, MPEG4, or H.264 standards. The central processing module  13  decompresses the integrated signal provided by the USB hub  12  and generates at least one recovered video signal. The recovered video signal is then displayed by the display module  14 . In actual applications, the display module  14  can be an LCD or CRT display assembled nearby the driver&#39;s seat. 
     As shown in the embodiment above, by integrating video signals from plural image detecting modules  11  with the USB hub  12 , the number of cables connected to the central processing module  13  and the display module  14  can be substantially reduced in the image monitoring system  10  according to the invention. The configuration of transmission cables is accordingly not so complicated. For vehicles having only small inner spaces, this advantage is particularly important. 
     As shown in  FIG. 1(B) , the image monitoring system  10  can further include the second group of image detecting modules  11  connected to the central processing module  13  via another USB hub  12 . For example, one of the USB hubs  12  can be used for integrating the image detecting modules  11  assembled at the rear part of the vehicle, and the other USB hub  12  can be used for integrating the image detecting modules  11  assembled at the front part of the vehicle. Accordingly, numerous transmission cables originally connected from different locations to the central processing module  13  are simplified to only two transmission cables. 
       FIG. 1(C)  illustrates another exemplary embodiment according to the invention. In this embodiment, one of the two USB hubs  12  is connected to the central processing module  13  via the other USB hub  12 . As long as the USB cable can afford the data amount contributed from all the image detecting modules  11 , this kind of connection structure is also practicable. 
     Please refer to  FIG. 2 , which shows the image monitoring system in another embodiment according to the invention. In this embodiment, the digital image processor  11 B further includes a feedback unit  11 E. The feedback unit  11 E generates a feedback signal for adjusting the image detector  11 A based on the processing result of the digital image processing procedure in the digital image processor  11 B. This feedback signal can be related to an exposure setting, a white balance setting, a resolution setting, or a color setting of the image detector  11 A. For example, if the digital image processor  11 B finds the brightness of images captured by the image detector  11 A is not enough, the feedback unit  11 E can automatically generate a control signal to increase the exposure amount of the image detector  11 A. 
     Besides, the central processing module  13  in this embodiment further includes a compression-ratio determining unit  13 A and a resolution determining unit  13 B. The two units are used for determining the compression-ratio and resolution of the image detecting modules  11  based on the transmitting limitation of the USB hub  12  and the number of the image detecting modules  11  connected to the USB hub  12 . 
     In other words, when there are fewer image detecting modules  11  connected to the USB hub  12 , the compression-ratio determining unit  13 A can suggest the image compressors  11 C to adopt lower compression-ratio, so as to reduce the image quality loss which is caused by image compression. On the contrary, when there are more image detecting modules  11 , the compression-ratio determining unit  13 A can suggest the image compressors  11 C to adopt higher compression-ratio, so as to reduce the data amount outputted from the image detecting modules  11  and accordingly make the final integrated signal be affordable by the transmission bandwidth of USB cable. 
     On the other aspect, when there are fewer image detecting modules  11  connected to the USB hub  12 , the resolution determining unit  13 B can suggest the image detectors  11 A to adopt a higher resolution, so as to increase the image quality. On the contrary, when there are more image detecting modules  11 , the resolution determining unit  13 B can suggest the image detectors  11 A to adopt a lower resolution, so as to reduce the data amount outputted from the image detecting modules  11  and accordingly make the integrated signal be affordable by the transmission bandwidth of USB cable. 
     Please refer to  FIG. 3(A) , which shows the image monitoring system in another embodiment according to the invention. In this embodiment, the image monitoring system further includes a user interface  15 , a storage module  16 , a wireless communication module  17 , a speaker  18 , and one or two digital microphone  19 . 
     The user interface  15  can be assembled in a gauge board or on a rear-view mirror of the vehicle. Users can input a user command via this user interface  15 . Practically, the user interface  15  can be a touch-control panel integrated with the display module  14 . In addition, the user interface  15  can include keyboards or knobs adjacent to the display module  14 . 
     The central processing module  13  can adjust the at least one recovered video signal according to user commands. For example, when the vehicle is moving backward, the driver may want the display module  14  to display images captured by the image detecting modules  11  assembled at the rear part of the vehicle. Via the user interface  15 , users can select which captured images are going to be displayed on the display module  14 . According to this user command, the central processing module  13  will select the requested ones from the decompressed signals and transmit them to the display module  14 . Besides, the user command may also represent that the user wants to enlarge images captured by certain image detecting module  11 . 
     The storage module  16  is electrically connected to the central processing module  13 , too. The function of the storage module  16  is storing the integrated signal outputted from the USB hub  12 , the recovered video signal generated by the central processing module  13 , signals with the same compression format of those outputted from the image compressors  11 C, or signals being further compressed by the central processing module  13  with a higher compression-ratio. The signals stored in the storage module  16  are prepared for conditions if users want to review previous images. In actual applications, the storage module  16  can be a hard disk device or a removable memory card. 
     The wireless communication module  17  can be used for receiving a remote control signal for controlling the central processing module  13  from a remote system. The wireless communication module  17  can also be used for transmitting a monitoring result provided by the central processing module  13  to a remote system. For example, the image monitoring system can be connected with a security system via the wireless communication module  17 . If the central processing module  13  or the driver finds something wrong, the wireless communication module  17  can be controlled to transmit a message of asking for help to the security system. Further, the remote security system can also receive images captured by the image detecting modules  11  via the wireless communication module  17 . 
     Moreover, the wireless communication module  17  can be used for receiving newer firmware for the central processing module  13  from a remote system. By doing this, the operations and functions of the central processing module  13  can be updated or modified. In actual applications, the wireless communication module  17  can conform to one or more wireless communication standards. 
     The speaker  18  is used for receiving an audio signal from the central processing module  13  and broadcasting the audio signal. This audio signal may be a warning message generated by the central processing module  13  based on the integrated signal. The central processing module  13  might generates the warning message, for instance, to warm the driver that the vehicle is too close to certain exterior objects. The microphone  19  is used for receiving an external voice signal, such as a voice command of the user, and transmitting the external voice signal to the central processing module  13 . 
     As shown in  FIG. 3(B) , speaker  18  and microphone  19  can be connected to the central processing module  13  via a high definition multimedia interface (HDMI) apparatus  20 . The wireless communication module  17  can also be connected to the central processing module  13  via a certain USB hub  12  and the HDMI interfacing apparatus  20 . At the present time, the most commonly used HDMI interface has nineteen pins. In the image monitoring system according to the invention, two of these pins can be utilizes for transmitting USB signals to the central processing module  13 . 
     Please refer to  FIG. 4 , which shows the image monitoring system in another embodiment according to the invention. This image monitoring system includes a plurality of image detecting modules  11 , a wireless communication module  17 , a USB hub  12 , an HDMI interfacing apparatus  20 , a central processing module  13 , a display module  14 , and a control panel with a memory card interface  21  and a touch-control panel  22 . This control panel can be assembled on the gauge board or on a rear-view mirror. 
     The memory card interface  21  is used for assisting the central processing module  13  in connecting to a removable memory card, such as a secure digital (SD) card, a compact flash (CF) card, or memory cards of other formats. Thereby, the user can copy images captured by the image detecting modules  11  on the vehicle to other personal computer systems. 
     In this embodiment, the touch-control panel  22  is integrated with the display module  14 . Users are capable of inputting user commands for controlling the central processing module  13  via this touch-control panel  22 . Besides, if the display module  14  can show number keys, the image monitoring system can further utilize the wireless communication module  17  mentioned above to provide the service of making phone calls in the vehicle by receiving phone numbers via the touch-control panel  22 . 
     As described above, by utilizing hubs to integrate signals from plural image detecting modules and other peripheral devices, the number of transmission cables connected to the central control apparatus and the display panel is considerably reduced. The complexity and cost of setting up of the system are both decreased. Further, the complexity of maintaining this system is lowered as well. It can be seen that the image monitoring system according to the invention is especially suitable for vehicles with limited inner spaces. Similarly, for apartment buildings, offices, or public places where a higher space utility is required, the image monitoring system according to the invention can also be used. 
     With the example and explanations above, the features and spirits of the invention will be hopefully well described. Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teaching of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.