Patent Publication Number: US-2019187800-A1

Title: Backlight embedded infrared proximity sensing and gesture control

Description:
CROSS-REFERENCED TO RELATED APPLICATIONS 
     This application claims benefit of U.S. Provisional Application No. 62/607,502 filed on Dec. 19, 2017, which the disclosure of which is hereby incorporated by reference in its entirety for all purposes. 
    
    
     FIELD OF THE INVENTION 
     The disclosure relates to proximity sensing and gesture control in a motor vehicle. 
     BACKGROUND OF THE INVENTION 
     Proximity sensing and gesture control are becoming more popular in consumer devices. Several cellular phone manufactures offer gesture control options. 
     Currently there are several approaches for proximity sensing methods. One such method involves using a camera. Advantages of a camera is that it has good range, and enables superior gesture sensing. A disadvantage of a camera is that it is expensive. Another method for proximity sensing involves using analyzing sound. Although this technique has great potential, it is not a proven technology. 
     SUMMARY 
     According to the present invention, a vehicle may include an infra-red light source incorporated into a display to perform proximity and gesture recognition. Using infra-red energy as a standalone solution for proximity sensing is inexpensive and easy to implement. However, the range of infra-red is limited by the power of the light source. Also, the use of infra-red energy requires dedicated LEDs, which occupies additional space under the dashboard. 
     In one embodiment, the invention comprises a motor vehicle including a display screen having a plurality of light emitting diodes emitting visible light. The display screen also has at least one infra-red energy-emitting element. An infra-red photo detector receives infra-red energy emitted by the infra-red energy-emitting element and reflected by a person within a passenger compartment of the motor vehicle. An electronic processor is communicatively coupled to the infra-red photo detector. The electronic processor receives signals from the infra-red photo detector. The electronic processor determines, based on the signals, a position of a body part of the person within the passenger compartment of the motor vehicle. 
     In another embodiment, the invention comprises a method for operating a motor vehicle, including providing a display screen having a plurality of light emitting diodes emitting visible light, and at least one infra-red energy-emitting element. An infra-red photo detector is used to receive infra-red energy emitted by the infra-red energy-emitting element and reflected by a person within a passenger compartment of the motor vehicle. Signals are received from the infra-red photo detector. It is determined, based on the signals, a position of a body part of the person within the passenger compartment of the motor vehicle. 
     In yet another embodiment, the invention comprises a display screen including a plurality of white light emitting diodes emitting white light, and a plurality of infra-red light emitting diodes emitting infra-red energy. A bezel surrounds the white light emitting diodes and the infra-red light emitting diodes. A plurality of infra-red photo detectors are spaced apart on the bezel. Each of the infra-red photo detectors receives infra-red energy that is emitted by the infra-red light emitting diodes and that is reflected by a person disposed in front of the display screen. 
     The present invention may enable proximity sensing to be performed at the same high level of camera-based systems while occupying a relatively small amount of space and being relatively inexpensive. 
     The proximity sensing system of the present invention may be a part of the display assembly, and may have an infra-red transmitter that is a part of the backlight circuit. This provides the transmitter with greater power and thus enables a greater amount of infra-red light to be emitted, which results in superior performance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A better understanding of the present invention will be had upon reference to the following description in conjunction with the accompanying drawings. 
         FIG. 1  is a diagram of one embodiment of a sub-pixel arrangement of the present invention for a display screen. 
         FIG. 2  is a diagram of one embodiment of a liquid crystal display arrangement of the present invention. 
         FIG. 3  is a timing diagram for energization of the white LEDs and IR LEDs of  FIG. 2  according to one embodiment. 
         FIG. 4  is a flow chart of one embodiment of a method of the present invention for operating a motor vehicle. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  illustrates one embodiment of a sub-pixel arrangement  10  of the present invention for a display screen. Arrangement  10  forms a pixel having three sub-pixels, including a red sub-pixel  12 , a green sub-pixel  14 , and a blue sub-pixel  16 . Arrangement  10  also has an infra-red (IR) transmitter  18  which may have the size, placement and shape of a sub-pixel, but which transmits infra-red energy out of the display screen. It is possible to use any pixel arrangement including sub pixels creating colors (e.g., the sub-pixels are not limited to red, green, blue) and an infra-red component. 
       FIG. 2  illustrates one embodiment of a liquid crystal display arrangement  100  of the present invention, having five aligned light-emitting diodes (LEDs), including three white LEDs  102 ,  104 ,  106  in the middle, and two IR LEDs  108 ,  110  on the ends. IR LEDs  108 ,  110  may be driven independently of the other LEDs  102 ,  104 ,  106 . IR signals may be transmitted by IR LEDs  108 ,  110  between normal video frames. This arrangement may be applied to LCDs, OLED displays, or any displays developed in the future. 
     The number of IR LEDs and the physical arrangement of the LEDs can vary within the scope of the invention based on the display resolution and other design requirements. Local dimming can be used to improve the performance of the IR LEDs. The IR LEDs can also be time multiplexed and may work together with the white LEDs. 
     The IR LEDs can be physically arranged in any pattern with the white LEDs. Both the IR LEDs and the white LEDs can be enabled, or turned ON, at the same time. It is also possible for the IR LEDs and the white LEDs to be driven at different times. The time duration and duty cycle of the ON/OFF cycle can be adjusted to meet requirements. When the display is off (e.g., when the display is not showing any image) the IR LEDs can be still enabled and the IR subpixel can be programmed to be in the open position when the display is off. 
       FIG. 3  illustrates the timing of energization of white LEDs  102 ,  104 ,  106  and IR LEDs  108 ,  110  according to one embodiment. The time duration of one frame  112 , including both energizing of the white LEDs and a subsequent energizing of the IR LEDs, may be about 16.667 milliseconds in one embodiment. 
     Referring again to  FIG. 2 , liquid crystal display arrangement  100  may include a rectangular bezel  114  having four IR photo detectors  116   a - d , one IR photo detector being at each of the four corners of bezel  114 . The number of IR photo detectors and their locations and positions can vary based on the design requirements. 
     The present invention has several benefits. First, there is no need for a dedicated space for IR hardware. Thus, there is a better utilization of space. Second, the gesture detection area and distance can be controlled by the amount of the IR light coming out of the display. Third, the total cost is low and is on par with current IR solutions. 
     During use, IR LEDs  108 ,  110  emit IR energy into the passenger compartment of the motor vehicle. The IR energy reflects off of the human passengers within the passenger compartment and back toward liquid crystal display arrangement  100 . IR photo detectors  116   a - d  detect the reflected IR energy. An electronic processor (not shown) receives signals from IR photo detectors  116   a - d  and determines based thereon the positions, locations, movements, and gestures of the passengers of the motor vehicle. 
     Although the IR photo detectors are shown as being disposed on a bezel of the display screen, it is to be understood that it is also possible within the scope of the invention for the IR photo detectors to be disposed off of or beside the display screen. 
       FIG. 4  illustrates one embodiment of a method  400  of the present invention for operating a motor vehicle. In a first step  402 , a display screen is provided including light emitting elements emitting visible light, and at least one infra-red energy-emitting element. For example, liquid crystal display arrangement  100  includes visible light-emitting diodes (LEDs) in the form of three white LEDs  102 ,  104 ,  106 , and infra-red energy-emitting LEDs  108 ,  110 . 
     Next, in step  404 , an infra-red photo detector is used to receive infra-red energy emitted by the infra-red energy-emitting element and reflected by a person within a passenger compartment of the motor vehicle. For example, IR photo detectors  116   a - d  detect the IR energy reflected off of the human passengers within the passenger compartment and back toward liquid crystal display arrangement  100 . 
     In a next step  406 , signals are received from the infra-red photo detector. For example, an electronic processor receives signals from IR photo detectors  116   a - d.    
     In a final step  408 , a position of a body part of the person within the passenger compartment of the motor vehicle is determined based on the signals. For example, the electronic processor determines, based on the received signals, the positions, locations, movements, and gestures of the passengers of the motor vehicle. 
     The foregoing description may refer to “motor vehicle”, “automobile”, “automotive”, or similar expressions. It is to be understood that these terms are not intended to limit the invention to any particular type of transportation vehicle. Rather, the invention may be applied to any type of transportation vehicle whether traveling by air, water, or ground, such as airplanes, boats, etc. 
     The foregoing detailed description is given primarily for clearness of understanding and no unnecessary limitations are to be understood therefrom for modifications can be made by those skilled in the art upon reading this disclosure and may be made without departing from the spirit of the invention.