Patent Publication Number: US-2009237385-A1

Title: Display Apparatus and Power Control Circuit thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from the prior Taiwanese Patent Application No. 097109718, filed Mar. 19, 2008, the entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     1. Field of the Invention 
     The disclosed embodiments of the present invention relate to a display apparatus and a power control circuit thereof, and more specifically to a display apparatus and a power control circuit thereof, which does not use a microprocessor to detect the state of the display apparatus and the power control circuit thereof, and may automatically save power consumption of the display apparatus and the power control circuit thereof if no signal is inputted. 
     2. Description of the Related Art 
     Display apparatus is an information-providing device widely used by people. The display apparatus is configured for providing various patterns and characters to transmit the information more conveniently. However, with the development of the modern society, it is more and more important to save power. The information-providing device is also needed to save power. At present, the display apparatus may be divided into two types with the saving-power mode, one type is automatically entering into the saving-power mode after not using the display apparatus for a predetermined time; and the other is automatically entering into the saving-power mode if no signal inputting. 
     Referring to  FIG. 1 , a typical power control circuit of a display apparatus is provided. Generally, the typical power control circuit  10  employs a switch  120  for controlling whether power supplied from a power supply  130  is transmitted to an electronic element  140 . The switch  120  is controlled (turned on/off) according to a micro-process unit  110  detecting image signals. An image signal source  100  is used as an input terminal of the display apparatus to be configured for receiving the image signals. The image signals received from the image signal source  100  are transmitted to the micro-process unit  110  to perform essential processing programs. The essential processing programs including a determination program are configured for determining whether image signals have been inputted, to control the on-off state of the switch  120 . 
     The switch  120  is controlled by the micro-process unit  110  to determine whether the power is supplied to the electronic element  140 , such that the typical power control circuit  10  may save much more power. However, the micro-process unit  110  may operate incessantly and consume the power, such that the typical power control circuit  10  has a limit for saving the power. That is, even if the display apparatus enters into the saving-power mode, the power supply  130  also may supply the power to the micro-process unit  110 . If not, the micro-process unit  110  may not induce the display apparatus to enter into a normal mode from a saving-power mode. Therefore, the typical power control circuit  10  has the limit for saving the power. 
     What is needed is to provide a power control circuit, which may solve the above problems. 
     BRIEF SUMMARY 
     A display apparatus in accordance with one embodiment of the present invention is provided. The display apparatus may induce the display apparatus to enter into a normal mode from a saving-power mode without supplying power to a micro-process unit. 
     A power control circuit of a display apparatus in accordance with an exemplary embodiment of the present invention is provided. The power control circuit may automatically determine whether power supplied from the power supply is transmitted to an electronic element of the display apparatus without using the micro-process unit. The power control circuit includes an image signal input terminal, a resistor-capacitor (RC) filter and a switch. The image signal input terminal is configured for receiving an image signal and providing a waiting-for-processing signal corresponding to the image signal. The RC filter is configured for receiving the waiting-for-processing signal and filtering out an alternating-current (AC) component of the waiting-for-processing signal to generate a switch control signal. The switch is electrically connected between the power supply and the electronic element, and configured for receiving the switch control signal, and the switch control signal is configured for controlling on-off state of the switch. 
     A display apparatus in accordance with another exemplary embodiment of the present invention is provided. The display apparatus includes a power supply, an electronic element, a switch, a first image signal input terminal and a first RC filter. The power supply is configured for supplying power needed by the display apparatus. The switch is electrically connected between the power supply and the electronic element. The first image signal input terminal is configured for receiving a first image signal and providing a first waiting-for-processing signal corresponding to the first image signal. The first RC filter is electrically connected to the first image signal input terminal and configured for filtering out an AC component of the first waiting-for-processing signal to generate a first switch control signal for controlling on-off state of the switch. 
     The embodiments of the present invention employ the RC filter to achieve some specific signals (such as horizontal synchronous signal, vertical synchronous signal, or digital differential signal) from the image signals, and employ the specific signals to directly control the on-off state of the switch. Thus the embodiments of the present invention may easily control the output of the power without using the micro-process unit. 
     Other objectives, features and advantages of the present invention will be further understood from the further technological features disclosed by the embodiments of the present invention wherein there are shown and described preferred embodiments of this invention, simply by way of illustration of modes best suited to carry out the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1  is a circuit block diagram of a conventional power control circuit of a display apparatus. 
         FIG. 2  is a circuit block diagram of a display apparatus, in accordance with an exemplary embodiment of the present invention. 
         FIG. 3A  is a circuit block diagram of an RC filter in accordance with an exemplary embodiment of the present invention. 
         FIG. 3B  is a circuit diagram of the RC filter in accordance with an exemplary embodiment of the present invention. 
         FIG. 3C  is a circuit diagram of a switch signal generator in accordance with an exemplary embodiment of the present invention. 
         FIG. 4A  is a circuit block diagram of an image signal input terminal in accordance with another exemplary embodiment of the present invention. 
         FIG. 4B  is a circuit diagram of a filter amplifier in accordance with an exemplary embodiment of the present invention. 
         FIG. 5  is a circuit block diagram of a display apparatus in accordance with an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     It is to be understood that other embodiment may be utilized and structural changes may be made without departing from the scope of the present invention. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted,” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings 
     Referring to  FIG. 2 , a circuit block diagram of a display apparatus, in accordance with an exemplary embodiment, is provided. In this exemplary embodiment, the display apparatus  20  includes a power supply  200 , an electronic element  210  and a power control circuit  22 . The power control circuit  22  includes an image signal input terminal  220 , an RC (resistor-capacitor) filter  222  and a switch  224 . The power control circuit  22  is electrically connected between the power supply  200  and the electronic element  210  to control whether power supplied from the power supply  200  is transmitted to the electronic element  210 . More concretely, the image signal input terminal  220  receives an image signal from an image providing device (for example, a computer), and then transmits the image signal or a derived signal derived from the image signal (defined as a waiting-for-processing signal in following), to the RC filter  222 . The RC filter  222  receives the waiting-for-processing signal from the image signal input terminal  220 , and filters an AC (alternating-current) component of the waiting-for-processing signal to generate a switch control signal. The switch control signal is transmitted to the switch  224  for controlling on-off state thereof. The switch  224  is electrically connected between the power supply  200  and the electronic element  210 , and is controlled by the switch control signal to determine whether the power supplied from the power supply  200  is transmitted to the electronic element  210 . 
     Referring to  FIG. 3A , a circuit block diagram of the RC filter, is shown. In this exemplary embodiment, the RC filter  222  includes a RC filter circuit  300  and a switch signal generator  302 . The RC filter circuit  300  is configured for filtering the AC component of the waiting-for-processing signal to generate a tiny switch control signal. The tiny switch control signal is then transmitted into the switch signal generator  302 , and the switch signal generator  302  generates the switch control signal transmitted to the switch  224  as shown in  FIG. 2 , according to the tiny switch control signal. 
     Referring to  FIG. 3B , a circuit diagram of an RC filter circuit, is shown. In this exemplary embodiment, the RC filter circuit  30  includes two capacitors  310  and  314 , and a resistor  312 . One terminal of the capacitor  310  is electrically connected to an input terminal  305 , and another terminal thereof is electrically connected to one terminal of the resistor  312 . Another terminal of the resistor  312  is electrically connected to an output terminal  315  and one terminal of the capacitor  314 . Another terminal of the capacitor  314  is electrically connected to the ground. The RC filter circuit  30  receives the waiting-for-processing signal  32  via the input terminal  305 , and the waiting-for-processing signal  32  is filtered to get rid of the AC component thereof when passing through the capacitors  310 ,  314  and the resistor  312 , such that the tiny switch control signal  34  is generated at the output terminal. It should be noted that, if the waiting-for-processing signal  32  is an input signal as shown in  FIG. 3B , the tiny switch control signal  34  may be kept at a level substantially though it may be a tiny up-and-down wave. Relatively, if the waiting-for-processing signal  32  is kept at the low logic level (that is, no image signal being inputted), the tiny switch control signal  34  is also kept at the low logic level. The logic level of the tiny control signal  34  is controlled by adjusting the values of the capacitors  310 ,  314  and the resistor  312 . It should be obvious for persons skilled in the art to adjust the values of the capacitors and the resistor. 
     Referring to  FIG. 3C , a circuit diagram of the switch signal generator, is shown. In this exemplary embodiment, the input terminal of the switch signal generator  36  is electrically connected to the RC filter circuit  300  for receiving the tiny switch control signal sent therefrom. The tiny switch control signal is configured for changing the potential of an output node P 1 . If the tiny switch control signal has an enough potential to turn on a transistor Q 1 , the potential of the output node P 1  is close to the level of a power supply Vcc. Contrarily, if the potential of the tiny switch control signal is low and cannot turn on the transistor Q 1 , the potential of the output node P 1  is the ground potential. Furthermore, since a transistor Q 2  is turned on constantly, the potential of an output node P 2  is very close to the ground potential. Thus, the switch control signal sent from the switch signal generator  36 , is generated by comparing the potentials of the output nodes P 1  and P 2 . In this exemplary embodiment, the two output nodes P 1  and P 2  are designed since some circuits are turned on in the high logic level and some circuits are turned on in the low logic level. Therefore, the present switch signal generator  36  is suited for various circuits. The output node P 2  may be electrically connected to the circuits turned on in the low logic level; and the output node P 1  may be electrically connected to the circuits turned on in the high logic level. It should be noted that, if the circuit electrically connected to the present switch signal generator  36  is predetermined, the present switch signal generator  36  may only include one of the output nodes P 1  and P 2 . 
     The image signal input terminal  220  as shown in  FIG. 2  is discussed in the following for various image signals. It is well known that, the image signals may be divided into analog image signals and digital image signals. If the inputted image signals are the analog image signals, the image signal input terminal  220  as shown in  FIG. 2  is a pure input node. However, if the inputted image signals are the digital image signals, for example, the signals of the DVI (digital visual interface) standard or the signals of the HDMI (high-definition multimedia interface) standard, a corresponding circuit may be employed to process the signals. 
     Referring to  FIG. 4A , an interior circuit block diagram of the image signal input terminal, in accordance with another exemplary embodiment, is shown. In this exemplary embodiment, the image signal input terminal  40  is suited for processing the digital image signals. The image signal input terminal  40  includes a digital image signal input terminal  400 , a digital image signal buffer  410  and a filter amplifier  420 . The digital image signal input terminal  400  receives a digital image signal Din from the image providing device (for example, the computer), and transmits the digital image signal Din to the digital image signal buffer  410 . The digital image signal buffer  410  then transmits the digital image signal Din to the filter amplifier  420  and the micro-process unit (not shown) via two output paths, respectively. The digital image signal buffer  410  provides the digital image signal DVI- 1  to the filter amplifier  420 , and the filter amplifier  420  is configured for filtering out an DC (direct-current) component of the digital image signal DVI- 1  (generally being the DC carrier wave of the digital image signal Din) and amplifying a temporary storage data generated from filtering out the DC component of the digital image signal DVI- 1  to generate the waiting-for-processing signal provided to the RC filter  222  as shown in  FIG. 2 . 
     The digital image signal buffer  410  is an common electronic element in the market, for example, a product of EP9122 (HDMI Buffer(splitter)) type manufactured by the Explore Microelectronics Inc. Referring to  FIG. 4B , a circuit diagram of the filter amplifier, in accordance with an exemplary embodiment, is shown. In this exemplary embodiment, the filter amplifier  44  includes a digital image signal capacitor filter circuit  440  and an amplifier  460 . The digital image signal capacitor filter circuit  440  may be a capacitor  442 . One terminal of the capacitor  442  is configured for receiving the digital image signal DVI- 1  (defined as the temporary storage signal DVI- 1  in the following) provided to the filter amplifier  44  from the digital image signal buffer  410 . Another terminal thereof is electrically connected to the gate terminal of a transistor Q 3  of the amplifier  460 . The temporary storage signal DVI- 1  is inputted into the digital image signal capacitor filter circuit  440  and then filtered out the DC component by the capacitor  442 . A result (defined as the DC filtering-out signal in the following) generated from filtering out the DC component of the temporary storage signal DVI- 1  is transmitted to the amplifier  460 . 
     In this exemplary embodiment, the amplifier  460  includes the transistor Q 3 , resistors  462 ,  466  and  468 , and a capacitor  464 . The DC filtering-out signal is provided to the gate terminal of the transistor Q 3  to control on-off state thereof. The DC filtering-out signal is amplified by the amplifier  460 , and then sent out from an output node P 3  to be the waiting-for-processing signal sent from the image signal output terminal  40 . 
     It should be noted that, since the current digital image signal usually employs a group differential signals to transmit the data, and the change of the potentials of the group differential signals is little, the DC filtering-out component should be amplified for performing following processes. If the standard of the digital image signal is changed, the circuit as shown in  FIG. 4B  should be changed correspondingly. The circuit of the present invention is not limited in  FIG. 4B . 
     Referring to  FIG. 5 , a circuit block diagram of a display apparatus, in accordance with an exemplary embodiment, is provided. In this exemplary embodiment, the display apparatus  50  includes a power supply  52 , a micro-process unit  54 , an electronic element  56  and a power control circuit  58 . The power supplied from the power supply  52  is controlled by the power control circuit  58  to determine whether being transmitted to the micro-process unit  54  and the electronic element  56 . The power control circuit  58  includes an analog image signal input terminal  500  and an RC filter  502 ; a digital image signal input terminal  510 , a digital image signal buffer  512 , a filter amplifier  514  and a RC filter  516  related to the inputting and detecting of the digital image signal; and a switch  520 . The operating mode and corresponding circuit of any element has been described in  FIG. 2  to  FIG. 4B , respectively. The switch control signal (defined as the first switch control signal in the following) sent from the RC filter  502  and/or the switch control signal (defined as the second switch control signal in the following) are used to control the on-off state of the switch  520 . Generally, the switch  520  may be a MOS (metal-oxide semiconductor) transistor. Of course, the switch  520  may be an other-type switch. 
     Once the first switch control signal and/or the second switch control signal represent that the analog image signal or the digital image signal is inputted into the display apparatus  50 , the switch  520  is turned on, and the power is supplied from the power supply  520  to the micro-process unit  54  and the electronic element  56  for processing the analog image signal (defined as the first image signal) received from the analog image signal input terminal  500  and/or the digital image signal (defined as the second image signal) received from the digital image signal input terminal  510 . In this condition, the electronic element  56  is normally operated because of supplying the power. Contrarily, if the first switch control signal and the second switch control signal both represent that no image signal is inputted into the display apparatus  50 , the switch  520  is turned off, and the display apparatus  50  may enter into the saving-power mode to decrease the power consumptions. 
     From the above, the embodiments of the present invention employ a logic circuit to detect the inputted image signal, thus it may determine easily whether the power supplied from the power supply is transmitted to the whole display apparatus without using the micro-process unit. Thus, the power of the display apparatus may be controlled easily, and the display apparatus may further save the power without using the micro-process unit in the saving-power mode. The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form or to exemplary embodiments disclosed. Accordingly, the foregoing description should be regarded as illustrative rather than restrictive. Obviously, many modifications and variations will be apparent to practitioners skilled in this art. The embodiments are chosen and described in order to best explain the principles of the invention and its best mode practical application, thereby to enable persons skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use or implementation contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents in which all terms are meant in their broadest reasonable sense unless otherwise indicated. Therefore, the term “the invention”, “the present invention” or the like does not necessarily limit the claim scope to a specific embodiment, and the reference to particularly preferred exemplary embodiments of the invention does not imply a limitation on the invention, and no such limitation is to be inferred. The invention is limited only by the spirit and scope of the appended claims. The abstract of the disclosure is provided to comply with the rules requiring an abstract, which will allow a searcher to quickly ascertain the subject matter of the technical disclosure of any patent issued from this disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Any advantages and benefits described may not apply to all embodiments of the invention. It should be appreciated that variations may be made in the embodiments described by persons skilled in the art without departing from the scope of the present invention as defined by the following claims. Moreover, no element and component in the present disclosure is intended to be dedicated to the public regardless of whether the element or component is explicitly recited in the following claims.