Abstract:
A light emitting touch pad includes a transparent touch sensor and a light emitting display apparatus. The transparent touch sensor is configured for sensing the position where an object touches the light emitting touch pad. The light emitting display apparatus is disposed at a side of the transparent touch sensor and configured for providing a surface light source emitting light toward the transparent touch sensor.

Description:
BACKGROUND 
       [0001]    The present invention relates to a touch pad and a control system having the same, and more particularly to a light emitting touch pad and a control system having the same. 
         [0002]    For an electronic apparatus, it is normally necessary to have an input device. Common input devices can be generally divided into two categories. One includes button devices such as keyboards. The other includes pointing devices such as mice or trackballs. With the development of technology, both of these input devices can be replaced by touch pads. 
         [0003]    In laptop computers touch pads have been widely used to replace mice. In addition, some control systems have been developed to use touch pads to generate different signals as a user touches different positions of a touch pad. Furthermore, manufactures now provide light sources inside touch pads for users to use touch pads in dark environment. All the touch pads with light sources inside (which are referred as light emitting touch pads in the following) that we commonly see today use point light sources. Referring to  FIG. 1 , an exploded view of a light emitting touch pad  10  using point light sources. The light emitting touch pad  10  includes a thin film  100  and a touch sensor  110 . The touch sensor  110  has multiple small holes formed thereon. Point light sources  111 ,  112 ,  113 ,  114  and  115 , which can be light emitting diodes (LEDs), are respectively disposed in the small holes. 
         [0004]    However, as shown in  FIG. 1 , the point light sources in a way undermine the integrity of the touch sensor  110  and further discontinue the linearity of the touch sensor  110  so as to degrade the sensing resolution of the touch sensor  110 . In addition, due to the existence of the point light sources, the whole size of the light emitting touch pad  10  is limited and can not be smaller. Furthermore, point lighting may cause uneven surface illumination of the light emitting touch pad  10 . 
       BRIEF SUMMARY 
       [0005]    One objective of the present invention is to provide a light emitting touch pad that not only can provide an even surface illumination but also solve the problem of further miniaturizing the light emitting touch pad that exists in conventional light emitting touch pad with point light sources. 
         [0006]    Another objective of the present invention is to provide a control system having a light emitting touch pad. The sensing linearity of the control system is not compromised as in using conventional point light sources. 
         [0007]    In one embodiment of the present invention, a light emitting touch pad includes a transparent touch sensor configured for sensing the position where an object touches the light emitting touch pad, and a light emitting display apparatus disposed at a side of the transparent touch sensor and configured for providing a surface light source emitting light toward the transparent touch sensor. The transparent touch sensor can be a resistive touch sensor or a capacitive touch sensor. When the transparent touch sensor is a capacitive touch sensor, the light emitting touch pad can further include an isolation layer. The isolation layer is disposed between the transparent touch sensor and the light emitting display apparatus and configured for reducing electromagnetic interference which the transparent touch sensor receives from the light emitting display apparatus. 
         [0008]    In this embodiment, the light emitting touch pad further includes a thin film. The thin film and the light emitting display apparatus being disposed on different sides of the transparent touch sensor. At least a pattern is printed on the thin film. In another embodiment of the present invention, no pattern is printed on the thin film. Instead, the light emitting display apparatus projects a pattern onto the thin film. 
         [0009]    The present invention also provides a control system having a light emitting touch pad. The control system includes a light emitting touch pad, a control circuit and a system unit. The light emitting touch pad uses a light emitting display apparatus as a light source. The control circuit is configured for controlling lighting conditions of the light emitting display apparatus according to a control signal and for processing electronic signals generated by the light emitting touch pad. The system unit is configured for controlling the operation of the control circuit and for communicating with the control circuit by signals including the control signal to further control the operation of the control system. 
         [0010]    The present invention uses a surface light source in the light emitting touch pad so as to achieve an even surface illumination without degrading the linearity of the touch sensor and to solve the problem of further miniaturizing the light emitting touch pad that exists in conventional light emitting touch pad with point light sources. In addition, because the structure of the touch sensor is not damaged by the light sources, the control system can keep its sensing linearity so that the sensing resolution of the control system is not compromised for providing light in the light emitting touch pad. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    These and other features and advantages of the various embodiments disclosed herein will be better understood with respect to the following description and drawings, in which like numbers refer to like parts throughout, and in which: 
           [0012]      FIG. 1  is an exploded view of a conventional light emitting touch pad using point light sources; 
           [0013]      FIG. 2  is circuit block diagram of a control system having a light emitting touch pad in accordance with an embodiment of the present invention; 
           [0014]      FIG. 3  illustrates a lighting condition of the light emitting display apparatus in accordance with an embodiment of the present invention; and 
           [0015]      FIG. 4  is an exploded view of a light emitting touch pad in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Referring to  FIG. 2 , a control system  20  having a light emitting touch pad in accordance with a first embodiment of the present invention is provided. The control system  20  includes a system unit  200 , a control circuit  210  and a light emitting touch pad  220 . The light emitting touch pad  220  includes a transparent touch sensor  222  and a light emitting display apparatus  224 . 
         [0017]    As a whole, the operation of the control system  20  is controlled by the system unit  200 . The light emitting touch pad  220  acts as an interface for inputting data. The control circuit  210  controls the light emitting touch pad  220  according to control signals outputted by the system unit  200 . On the other hand, the control circuit  210  can process electronic signals generated by the light emitting touch pad  220  and send the signals, which represent input data inputted by the light emitting touch pad  220 , resulted from such processing to the system unit  200 . By this way, the system unit  200  can control the operation of the whole control system  20  according to the input data. For example, the control system  20  can be an electronic computer, and the light emitting touch pad  220  may have shapes of numbers and mathematical operators defined thereon. Or, as another example, the control system  20  can be an electronic dictionary, and the light emitting touch pad  220  may have shapes of English alphabets defined thereon. 
         [0018]    In this embodiment, the light emitting display apparatus  224  is used as a light source in the light emitting touch pad  220 . Based on the lighting characteristics of the light emitting display apparatus  224 , the control circuit  210  can control the lighting conditions of the light emitting display apparatus  224  such as lighting area, colors and etc. according to the above-mentioned control signals. By this way, a designer can configure the light emitting display apparatus  224  for lighting patterns on the light emitting touch pad  220  and further for conveniently sending users a visual message by changing the lighting conditions of the light emitting display apparatus  224 . For example, referring to  FIG. 3 , the light emitting display apparatus  30  is divided into multiple hexagon regions  300 , each of which can be individually controlled by the control circuit  210  as shown in  FIG. 2  to emit light or not emit light. The color of the light emitted by each of the hexagon regions  300  can be individually controlled by the control circuit  210  as well. 
         [0019]    Referring to  FIG. 4 , the light emitting touch pad  40  includes a light emitting display apparatus  400 , an isolation layer  410 , a transparent touch sensor  420  and a thin film  430 . The thin film  430  can be a Mylar® film. The light emitting display apparatus  400  and the thin film  430  are respectively disposed on different sides of the touch sensor  420 . By this configuration, the light emitted by the light emitting display apparatus  400  can transmit through the transparent touch sensor  420  and project on the thin film  430 . A pattern for allowing a user to recognize the different functions of the different regions can be printed on the thin film  430 , or alternatively, the same object can be achieved by controlling the lighting conditions of the light emitting display apparatus  400  without printing patterns on the thin film  430 . The isolation layer  410  is configured for shielding and reducing the electromagnetic interference (EMI) which the transparent touch sensor  420  receives from the light emitting display apparatus  400 . The isolation layer  410  is normally grounded. 
         [0020]    Since the purpose of using the thin film  430  is to protect the transparent touch sensor  420 , if the transparent touch sensor  420  is fairly hard to be damaged then the thin film  430  may be not necessary. In addition, for common transparent touch sensors, resistive touch sensors are relatively not very susceptible to EMI, so when a resistive touch sensor is used as the transparent touch sensor  420 , the isolation layer  410  may be not necessary. Alternatively, even a capacitive touch sensor is used as the transparent touch sensor  420 , if there is no EMI phenomenon happening or the EMI does not cause any operational error, the isolation layer  410  may still be eliminated. 
         [0021]    In summary, the present invention uses a surface light source in the light emitting touch pad so as to achieve an even surface illumination without degrading the linearity of the touch sensor. In addition, by using the isolation layer to lower the possible EMI associated with using the surface light source, the reliability of the light emitting touch pad is ensured. 
         [0022]    The above description is given by way of example, and not limitation. Given the above disclosure, one skilled in the art could devise variations that are within the scope and spirit of the invention disclosed herein, including configurations ways of the recessed portions and materials and/or designs of the attaching structures. Further, the various features of the embodiments disclosed herein can be used alone, or in varying combinations with each other and are not intended to be limited to the specific combination described herein. Thus, the scope of the claims is not to be limited by the illustrated embodiments.