Patent Publication Number: US-8542277-B2

Title: Controlling apparatus and controlling method for signal outputing circuit and video system

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
     This application is a divisional application of U.S. patent application Ser. No. 12/427,525, filed Apr. 21, 2009, now U.S. Pat. No. 8,233,253, the entire contents of which are incorporated herein in their entireties by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electronic system, and more particularly, to a signal outputting circuit of the electronic system. 
     2. Description of the Prior Art 
     The electro-static discharge (ESD) refers to the charge transfer phenomenon caused by objects with different electro-static potentials approaching each other or contacting each other directly. In recent years, with the rapid development of the technology, the microelectronic technique has been extensively applied and the electromagnetic environment has become more and more complex. As a result, the problems caused by the ESD in electronic products have attracted more and more attentions. 
     The interferences of the ESD on circuits are divided into two situations. In one situation, the ESD current passes the circuits directly to cause damages. In the other situation, the electromagnetic field induced by the ESD current disturbs the circuits by ways of a capacitance coupling, an inductance coupling, and a space radiation coupling, etc. 
     Generally, static electricity with different levels exists in humans and environments. When the accumulated static electricity reaches to a certain amount and then is contact with electronic devices, a discharge phenomenon will happen instantaneously. This natural discharge phenomenon will cause electronic devices, such as computers, mobile phones, PDAs or liquid crystal screens, etc, damaged seriously or work improperly. 
     For example, if the liquid crystal display system is interfered by the ESD, then the interference may further affect the chip circuit in the video system, and the signals, transmitted from the image processing circuit to the liquid crystal screen, are disturbed to generate errors. The abnormal signals may cause twinkling or unstable display, and may further affect the displaying property of the screen. 
     SUMMARY OF THE INVENTION 
     In order to solve the above-mentioned problem, the present invention is to provide a controlling apparatus, and the controlling apparatus of the invention can be adapted to a signal outputting circuit in the video system. The controlling apparatus is for selectively controlling the switch connected to the signal outputting circuit according to whether an electronic system has an abnormal condition. 
     According to an embodiment of the invention, it is related to a controlling apparatus for a signal outputting circuit. The signal outputting circuit is located in an electronic system. The controlling apparatus comprises a detecting circuit, a switch and a controlling circuit. The detecting circuit is used for detecting that whether the electronic system has an abnormal condition. The switch is electrically connected between a signal receiving terminal and the signal outputting circuit. The controlling circuit is electrically connected between the detecting circuit and the switch. Once the detecting circuit detects that the electronic system has the abnormal condition, the controlling circuit sets the switch into a high-impedance state. 
     According to another embodiment of the invention, it is related to a video system. The video system comprises an image outputting circuit, a detecting circuit, a switch and a controlling circuit. The detecting circuit is used for detecting that whether the video system has an abnormal condition. The switch is electrically connected between a signal receiving terminal and the image outputting circuit. The controlling circuit is electrically connected between the detecting circuit and the switch, and once the detecting circuit detects that the video system has the abnormal condition, the controlling circuit sets the switch into a high-impedance state. 
     According to the invention, when the electronic system has the abnormal condition, the signal transmission to the signal outputting circuit or the signal transmission from the signal outputting circuit will be provisionally ceased until the abnormal condition is eliminated. By this action, erroneous output signals can be avoided to output to the video system to cause twinkling or unstable display. 
     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)  is a schematic diagram illustrating the controlling apparatus according to an embodiment of the invention. 
         FIG. 1(B)  is a circuit example of the switch in the controlling apparatus according to the invention. 
         FIG. 1(C)  illustrates the schematic of the signal outputting circuit having a plurality of input/output ends. 
         FIG. 2(A)  illustrates a circuit example of the detecting circuit and controlling circuit of the controlling apparatus. 
         FIG. 2(B)  is a timing diagram example illustrating the controlling signals of the invention. 
         FIG. 3(A)  illustrates another circuit example of the detecting circuit and the controlling circuit of the controlling apparatus. 
         FIG. 3(B)  is another timing diagram example illustrating the controlling signals of the invention. 
         FIG. 4(A)  is a schematic diagram illustrating the video system according to an embodiment of the invention. 
         FIG. 4(B)  is a partial circuit example illustrating the video system of the invention. 
         FIG. 5  is a signal timing diagram example in the video system of the invention. 
         FIG. 6  is a flow chart illustrating a controlling method according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Please refer to  FIG. 1(A) .  FIG. 1(A)  is a schematic diagram illustrating the controlling apparatus according to an embodiment of the invention. The controlling apparatus  1  is adapted to be disposed at a signal outputting circuit  130  in an electronic system. The controlling apparatus  1  comprises a detecting circuit  100 , a switch  110  and a controlling circuit  120 . The switch  110  is electrically connected between a signal receiving terminal  140  and the signal outputting circuit  130 . 
     The detecting circuit  100  is used for detecting that whether the electronic system has an abnormal condition, such as an electro-static discharge (ESD) condition. When the detecting circuit  100  detects that the abnormal condition does not exist in the electronic system, the controlling circuit  120  will set the switch  110  into a short-circuited state, and then the signal transmitting between the signal outputting circuit  130  and the signal receiving terminal  140  is allowable. In practice, the signal receiving terminal  140  can be a circuit node inside a screen used for receiving data from the signal outputting circuit  130 . Otherwise, the signal receiving terminal  140  can be a circuit node of the signal outputting circuit  130  used for receiving data from other circuits. 
     Once the electronic system has the abnormal condition, the controlling circuit  120  sets the switch  110  into a high-impedance state, which disconnects the signal outputting circuit  130  and the signal receiving terminal  140 . Therefore, the signal transmission to the signal outputting circuit  130  or the signal transmission from the signal outputting circuit  130  will be provisionally ceased. Not until the detecting circuit  100  detects the abnormal condition has been eliminated or lessened, does the controlling circuit  120  reset the switch  110  into the short-circuited state, and then the signal transmitting between the signal outputting circuit  130  and the signal receiving terminal  140  is allowable again. 
     In practice, the switch  110  can be a transmission gate, but not limited herein. Please refer to  FIG. 1(B) .  FIG. 1(B)  is a circuit example of the switch. As shown in  FIG. 1(B) , the detecting circuit  100  generates a controlling signal CTL according to whether the electronic system has the abnormal condition. The controlling circuit  120  generates the controlling signals LAT and LATN for controlling the switch  110  according to the controlling signal CTL. 
     In this example, the controlling signals LAT and LATN have opposite potentials. When the controlling signal LAT is a low-potential signal and the controlling signal LATN is a high-potential signal, the transmission gate will be short. When the controlling signal LAT is a high-potential signal and the controlling signal LATN is a low-potential signal, the transmission gate is cut-off (i.e. the high-impedance state). 
       FIG. 1(C)  illustrates the schematic of the signal outputting circuit  130  having a plurality of input/output ends. As shown in  FIG. 1(C) , each of the input/output ends in the signal outputting circuit  130  is connected to a transmission gate, and the transmission gates are controlled by the controlling circuit  120 . The circuit in  FIG. 1(C)  and the circuit in  FIG. 1(B)  are operated in the same way. The controlling circuit  120  generates the controlling signals LAT and LATN, according to the controlling signal CTL, for controlling the transmission gates to synchronously turn on/turn off. Thereby, the signal outputting circuit  130  and each of the signal receiving terminal (such as  140 A and  140 B) are connected or disconnected. 
     Please refer to  FIG. 2(A) .  FIG. 2(A)  illustrates a circuit example of the detecting circuit and controlling circuit of the controlling apparatus. In the example, the detecting circuit and the controlling circuit are consisted of resisters (R), capacitors (C), an inverter  320  and an NMOS transistor.  FIG. 2(B)  is a timing diagram example illustrating the controlling signals. When the voltage source VDD in  FIG. 2(A)  is interfered and has a transient voltage drop, the outputting voltage (i.e. the controlling signal CTL) of the inverter will correspondingly vary from a low-potential to a high-potential. 
     No matter in analog circuits or digital circuits, the fluctuation of the voltage VDD may be influenced by the environment to make the signal outputting circuit  130  work improperly. According to the voltage change of the controlling signal CLT, the controlling circuit  120  sets the switch  110  into a high-impedance state through the controlling signals LAT and LATN for cutting the signal transmission off. 
       FIG. 3(A)  illustrates another circuit example of the detecting circuit and the controlling circuit of the controlling apparatus. In the example, the detecting circuit and the controlling circuit are consisted of resisters (R), capacitors (C), two inverters ( 320 ,  340 ) and a PMOS transistor.  FIG. 3(B)  is another timing diagram example illustrating the controlling signals. 
     Similarly, when the voltage source VDD in  FIG. 3(A)  is interfered and has a transient voltage drop, the voltage drop will cause a low-potential pulse at the output end of the inverter  340 . Namely, a low-potential pulse occurs in the controlling signal CTL. The impulse is used to indicate that that the voltage VDD has an abnormal condition. Accordingly, the controlling circuit  120  sets the switch  110  into a high-impedance state through the controlling signals LAT and LATN for terminating the transmission of erroneous signals. 
     The controlling apparatus of the invention is applicative in a video system, such as a liquid crystal display system.  FIG. 4(A)  is a schematic diagram illustrating the video system according to another embodiment of the invention. The video system  2  comprises a detecting circuit  200 , a switch  210 , a controlling circuit  220 , an image outputting circuit  230  and a display unit  250 . The switch  210  is electrically connected between the image outputting circuit  230  and a signal receiving terminal  240  of the display unit  250 . 
       FIG. 4(B)  illustrates a partial circuit example of the video system  2 . In the example, the image outputting circuit  230  comprises a buffer circuit consisting of an operational amplifier, and the switch  210  consists of transmission gates. If the detecting circuit  200  does not judge that the video system  2  has an abnormal condition, the controlling circuit  220  sets the transmission gate  210  into a short-circuited state, so that the image signal from the image outputting circuit  230  can be transmitted through the transmission gate  210  and the signal receiving terminal  240  into the display unit  250 . For example, the display unit  250  could be a monitor, a mobile phone screen, etc. 
       FIG. 5  is a signal timing diagram example in the video system  2 . When the detecting circuit  200  detects that the video system  2  does have an abnormal condition, the controlling circuit  220  will send out a high-potential controlling signal for setting the switch  210  into a high-impedance state, so as to terminate the output of first data in the image signal no matter whether the first data has faults due to the abnormal condition. 
     After a period of time, e.g. 15 milliseconds, next data (i.e. second data) is generated. If the detecting circuit  200  does not judge that the video system  2  has the abnormal condition, the controlling circuit  220  will make the controlling signal have a low potential for setting the switch  210  into a short-circuited state, which will let the second data transmit through the switch  210  successfully. For example, when the video system  2  has an ESD condition, the controlling circuit  220  can control the switch  210  to be opened transiently, and thus erroneous output signals can be avoided to output to the display unit  250  to cause twinkling or unstable display. 
       FIG. 6  is a flow chart illustrating a controlling method according to an embodiment of the invention. Firstly, step S 102  is performed to detect whether an electronic system has an abnormal condition. In practice, the abnormal condition could be an ESD condition. If NO in step S 102 , step S 104  is performed to set a switch, electrically connected between a signal receiving terminal and a signal outputting circuit, into a short-circuited state. If YES in step S 102 , step S 106  is performed to set the switch into a high-impedance state. 
     According to the invention, when the electronic system has the abnormal condition, the signal transmission to the signal outputting circuit or the signal transmission from the signal outputting circuit will be provisionally ceased until the abnormal condition is eliminated. By this action, erroneous output signals can be avoided to output to the video system to cause twinkling or unstable display. 
     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.