Abstract:
Optical imaging is used for touch input to implement device and method for gesture detection for better durableness, high resolution, simplifier structure, higher reliability, less power consumption, and faster response. A touch surface is provided for gesture operation thereon, and under light projecting to the touch surface, images are captured by receiving light from the touch surface. The varying images are monitored to detect if any gesture operates on the touch surface, and if a predefined gesture is detected, a gesture signal is generated.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention is generally related to a device and a method for input detection and, more particularly, to an optical touch device and an optical touch method. 
       BACKGROUND OF THE INVENTION 
       [0002]    Touch input has been extensively applied and further developed into gesture input applications. For example, U.S. Pat. No. 7,966,578 provides a method for multi-touch gesture detection, which not only simplifies an input device but also allows intuitional input operation. Conventionally, however, gesture detection is carried out by using a resistive or capacitive touch pad or touch panel, and thus has some unconquerable problems. The resistive touch panel uses a flexible film to receive pressing of a stylus for generating deformation to identify a touch point, and thus is less durable, has poor location resolution, and is hard to implement multi-touch applications. The capacitive touch pad and touch panel are stronger, but their location resolution depends on trace density. Thus, the location resolution is inherently limited by the width of each trace itself and the pitch between adjacent traces, and can only be improved by an algorithm of a post-end circuit. Moreover, the large number of interconnections between the traces and the microcontroller chip adds difficulty in performing wire layout on a printed circuit board. Further, since the microcontroller chip has so many pins to be bonded to the traces, it is hard to be downsized, and the numerous bonding points thereof can also reduce the reliability. Additionally, the capacitance detection of one trace requires charging and discharge one or more traces, and thus consumes considerable power and takes a long time. For either a resistive touch panel or a capacitive touch pad or touch panel, input detection includes scanning all its sensors for completing a frame of raw data and thus requires high-speed scanning and high-speed calculation, and even with a high-speed hardware, the time for obtaining one frame of data is still relatively long, which makes the frame rate hard to be increased and the response to input operation slower. 
       SUMMARY OF THE INVENTION 
       [0003]    An objective of the present invention is to provide an optical touch device and a method for input detection of an optical touch device. 
         [0004]    Another objective of the present invention is to provide a device and a method for optical touch input by gesture detection. 
         [0005]    A further objective of the present invention is to provide an input device and an input method that integrate gesture detection with a mouse function. 
         [0006]    According to the present invention, an optical touch device includes a touch surface, a light source and an image sensor unit configured such that the light source provides light to project to the touch surface and the image sensor unit captures images by receiving light from the touch surface. The captured images are sent to a processing unit to identify if any gesture operates on the touch surface and to generate a corresponding gesture signal if a gesture is identified. 
         [0007]    According to the present invention, a method for input detection includes providing light to project to a touch surface, capturing images by receiving light from the touch surface, identifying the captured images to detect if any gesture operates on the touch surface, and generating a corresponding gesture signal if a gesture is detected. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    These and other objectives, features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings, in which: 
           [0009]      FIG. 1  is a system block diagram of a first embodiment according to the present invention; 
           [0010]      FIG. 2  is a hardware arrangement of the optical touch device shown in  FIG. 1  when it is applied to a mouse; 
           [0011]      FIG. 3  is a system block diagram of a second embodiment according to the present invention; 
           [0012]      FIG. 4  is a hardware arrangement of the optical touch device shown in  FIG. 3  when it is applied to a mouse; and 
           [0013]      FIG. 5  shows images of various gestures detected by an optical touch device according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]      FIG. 1  is a system block diagram of a first embodiment according to the present invention, in which an optical touch device  10  includes a touch surface  14  to receive gesture operation thereon, a light source  26  arranged to be optically coupled to the touch surface  14  such that it can provide light to project to the touch surface  14 , an image sensor unit  16  arranged to be optically coupled to the touch surface  14  such that it can capture images by receiving light from the touch surface  14  and generates an input signal Si to carry the captured images, and a processing unit  18  electrically coupled to the image sensor unit  16  to receive the input signal Si, to identify the images carried by the input signal Si to detect if any gesture operates on the touch surface  14 , and to generate a corresponding gesture signal Sg if a gesture is detected. When a finger touches the touch surface  14 , it will reflect light at the touch point, so that a light spot will appear in the image captured by the image sensor unit  16 . According to the number and the locations of light spots in an image, the processing unit  18  can identify the number and the locations of fingers on the touch surface  14 . From the varying images, the processing unit  18  can further identify change of the finger number and the moving direction of each finger to detect if any gesture operates on the touch surface  14 . As is well known, the image sensor unit  16  includes an optical sensor, such as a CMOS image sensor (CIS) and a charge coupled device (CCD), to convert the received light into electronic signals, and may further include a lens or a pinhole for imaging on the optical sensor. Preferably, the image sensor unit  16  operates with one or more frame rates to generate images in a unit of frame, thus the input signal Si will contain image contents in a manner of frame by frame in a time sequence, and then the processing unit  18  can compare the image contents in two or more successive frames to identify variation of the images. The processing unit  18  can further calculate the moving speed of a finger with the frame rate of the image sensor unit  16  and the detected displacement of the finger. Since the processing unit  18  can identify different gestures from the input signal Si, it can generate various gesture signals Sg corresponding to the detected gestures. 
         [0015]    The optical touch device  10  may further integrate a mouse function. For example, as shown in  FIG. 1 , a movement detection module  20  includes a core established by a rolling-ball mechanism, an optical sensor, a motion sensor or a gyroscope, to detect the movement of the optical touch device  10  for generating a movement signal Sm, and a transmission interface  22  receives and then convert the gesture signal Sg and the movement signal Sm into an output signal So, for example by encoding under a communication protocol, to send to a host  24 . Thus, the host  24  can control a cursor according to the movement signal Sm, and execute a command corresponding to the gesture signal Sg. A such integrated device may have a hardware arrangement as shown in  FIG. 2 . In a mouse housing  100 , the movement detection module  20  is mounted at the bottom of the mouse housing  100  such that when the mouse housing  100  is placed on an operational plane  30 , the movement detection module  20  is close to the operational plane  30 , and similarly to a typical optical mouse, the movement detection module  20  includes a light source  32  to provide light to project to the operational plane  30  through a lens and then reflected by the operational plane  30  to impart on an image sensor  34  through another lens, the image sensor  34  keeps its image capturing, and a processing unit (not shown in the figure) generates a movement signal Sm according to the varying images. In this embodiment, the touch surface  14  is on the upper surface of a light guide plate  12  mounted in a front part of the top of the mouse housing  100 , taking the place traditionally occupied by buttons and wheels of a conventional mouse, the light source  26  is fixed to a lateral of the light guide plate  12  and provides light of a specific wavelength, for example infrared ray, to project to the light guide plate  12 , and the provided light penetrating into the light guide plate  12  propagates within the light guide plate  12  by internal total reflection and has a portion scattered by the light guide plate  12  to penetrate through the touch surface  14  outward. If a finger touches the touch surface  14 , the finger will establish a reflective surface at the touch point to reflect light back into the mouse housing  100  and thus imparting on the image sensor unit  16 . In another embodiment, the light guide plate  12  only allows invisible light, such as infrared ray, to pass therethrough, thereby preventing interference caused by ambient visible light. In the embodiment shown in  FIG. 2 , by detecting the gesture operating on the touch surface  14 , the optical touch device can generate not only button signals and wheel signals as a normal mouse, but also many control signals that can not be generated by a normal mouse. 
         [0016]    Preferably, referring back to  FIG. 1 , in addition to the light source  26 , the optical touch device  10  further includes a light control unit  28  to control the light source  26 . For example, the light control unit  28  may turn off the light source  26  in shutdown or standby, or may maintain the light source  26  at a small mute current in standby, or may only turn on the light source  26  when the image sensor unit  16  is going to capture images. Additionally, the processing unit  18  may identify brightness of one or more images from the input signal Si and generate a control signal Sc accordingly, for the light control unit  28  to adjust light intensity of the light source  26  to optimize the clarity of the captured images by the image sensor unit  16 . Preferably, the processing unit  18  controls the light source  26  to be blinking fast during image capturing, so that the image sensor unit  16  will capture images when the light source  26  emits light and when the light source  26  does not emit light, respectively. Then, the difference between the images captured when the light source  26  emits light and when the light source  26  does not emit light can be used to eliminate the background value caused by ambient light. Since the image taken by the image sensor unit  16  when the light source  26  is off is the background value caused by ambient light, the interference from ambient light can be reduced by eliminating this background value. In other embodiments, it may switch the light projecting to the touch surface  14  by other means, for example using a shutter, such that the image sensor unit  16  can capture images when the light is on and off. 
         [0017]      FIG. 3  is a system block diagram of a second embodiment according to the present invention, in which an optical touch device  36  also integrates gesture detection with a mouse function, while the difference from the embodiment shown in  FIG. 1  is that this embodiment uses some common components to carry out the gesture detection and the mouse function. In the optical touch device  36 , a light source  26 , a light control unit  28 , a touch surface  14 , an image sensor unit  42  and a processing unit  44  establish a gesture detection module which operates as the embodiment shown in  FIG. 1 , and a light source  32 , the image sensor unit  42  and the processing unit  44  establish a movement detection module which executes the mouse function as the embodiment shown in  FIG. 2 . As shown in  FIG. 4 , the optical components are properly arranged, including lens and a reflector to establish the optical paths, such that the light reflected by the touch surface  14  and the light reflected by the operational plane  30  both incident upon the image sensor unit  42 . Since the optical touch device  36  uses a single image sensor unit  42  and a single processing unit  44  to accomplish the gesture detection and the movement detection, the costs can be reduced. Referring to  FIG. 3  and  FIG. 4 , the processing unit  44  provides control signals Sc 1  and Sc 2  for the light control units  28  and  40  to control the light sources  26  and  32 , respectively, for example, turning on and off the light sources  26  and  32  or adjusting light intensity of the light sources  26  and  32 . Preferably, the light sources  26  and  32  are controlled to provide light alternately in a time sequence, such that when the light source  26  emits light, the image sensor unit  42  captures images by receiving light from the touch surface  14  for generating an input signal Si 1 , and when the light source  32  emits light, the image sensor unit  42  captures images by receiving light from the operational plane  30  for generating an input signal Si 2 . The processing unit  44  processes the input signals Si 1  and Si 2  separately, thereby generating a gesture signal Sg and a movement signal Sm for a transmission interface  22  to convert into an output signal So to sent to a host  24  that executes a command corresponding to the gesture signal Sg and controls a cursor according to the movement signal Sm. Preferably, the processing unit  44  may identify brightness of one or more images from the input signals Sit and Si 2  to adjust light intensity of the light sources  26  and  32  for optimizing the clarity of the captured images, respectively. 
         [0018]    There have been many arts developed for gesture detection and relevant command execution. In addition to those commands for typical mouse operation, such as single click, double click, drag and scroll, there are popular commands such as zoom-in, zoom-out, rotate clockwise, rotate Anticlockwise, flip-up and flip-down, and more gesture-triggered commands may be found from related arts. In an embodiment, referring to the images shown in  FIG. 5 , various gestures can be predefined and then identified by detecting the number and the absolute movement or relative movement of fingers (i.e. light spots in the images), with corresponding commands listed in Table 1 in the following: 
         [0000]                                                  TABLE 1               Item No.   Finger No.   Gesture Type   Command                                1   1   Move to Right   Move to Right       2   1   Move to Left   Move to Left       3   1   Move Up   Move Up       4   1   Move Down   Move Down       5   1   Rotate Clockwise   Rotate Clockwise       6   1   Rotate Anticlockwise   Rotate Anticlockwise       7   1→2   Press &amp; Tape   Right Click       8   1→2   Press &amp; Tape   Left Click       9   2   Move to Right   Flip to Right       10   2   Move to Left   Flip to Left       11   2   Move Up   Flip Up       12   2   Move Down   Flip Down       13   2   Rotate Clockwise   Rotate Clockwise       14   2   Rotate Anticlockwise   Rotate Anticlockwise       15   2   Out to In   Zoom In       16   2   In to Out   Zoom Out       17   3   Move Up   Scroll Up       18   3   Move Down   Scroll Down                    
In different embodiments, the displacement and/or the moving speed of one or more fingers may be taken into consideration for gesture definition and identification. In other embodiments, gesture definition and corresponding commands may be user defined through the operating system or relevant software running on the host  24 , to optimize the operation.
 
         [0019]    In the optical touch devices  10  and  36 , the touch surface  14  is on a stiff plate such as a glass plate so is highly durable. The touch point on the touch surface  14  is imaged through optical sensing and thus, not only the image can be obtained instantly, but also the location resolution depends on the resolution of the image sensor unit  16  or  42 , which is much higher than the existing resistive touch panels and capacitive touch pads and touch panels. Moreover, the light sources  26  and  32  may be realized by LEDs to reduce power consumption. 
         [0020]    While the present invention has been described in conjunction with preferred embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and scope thereof as set forth in the appended claims.