Abstract:
Household appliances such as televisions require the continuous supply of power to a remote control receiving circuit and microcomputer to receive remote control signals when turned off. To reduce power consumption, charge is stored in a battery or capacitor to supply power to the microcomputer and remote control receiving circuit without continuous operation of an AC-DC converter. Before a voltage of the charge storing device is reduced below a given level, such as the lowest operating voltage of the microcomputer and remote control receiving circuit, the AC-DC converter is activated to charge the charge storing device. When the voltage rises to a given level, such as the highest operating voltage of the microcomputer and the remote control receiving circuit, the AC-DC converter stops charging the charge storing device, so that the operating frequency of the AC-DC converter is reduced.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a power circuit for domestic electrical appliances having a remote control function, and more particularly to a power circuit which reduces a current consumed in the household electrical appliances during a waiting period of time. 
     As a conventional power circuit for household or domestic electrical appliances having a remote control function, there has been known a power circuit using means for converting an a.c. voltage into a d.c. voltage (hereinafter referred to as “AC-DC converter”) as shown in a circuit diagram of FIG.  3 . That is, an output voltage of the AC-DC converter  101  permits a control circuit for remote control, in this example, a microcomputer and an infrared ray receiving circuit,  103  for producing an output signal  110  in response to an infrared signal  115  received from an external controller to be driven. 
     SUMMARY OF THE INVENTION 
     In the circuit of FIG. 3, in a domestic electrical appliance such as a television, power must be continuously applied to the infrared ray receiving circuit and the microcomputer because the electrical appliance receives a remote control signal even if an image reception turns off. This is called “waiting-time consumed power”. However, the efficiency of the AC-DC converter is low, and a power of about 1 W is consumed only for such a waiting-time consumed power. Under existing environmental issues, a demand has been made to reduce the consumed power at the waiting time as much as possible, which cannot be achieved by the existing circuit structure at all. 
     In order to solve the above problem, electricity is stored in electric charge storing means such as a secondary battery or an electric double layer capacitor so as to supply power to the microcomputer and the infrared ray receiving circuit without always operating the AC-DC converter. Before a voltage across the electric charge storing means becomes lower than a given value, specifically, the lowest operating voltage of the microcomputer and the infrared ray receiving circuit, the AC-DC converter is operated to charge the electric charge storing means whereas before the voltage rises to and the given voltage, specifically, the highest operating voltage of the microcomputer and the infrared ray receiving circuit, the AC-DC converter stops charging the electric charge storing means. With the above operation, the operating frequency of the AC-DC converter is reduced so that the power consumed by the AC-DC converter which is the worst in power efficiency is reduced, thereby making it possible to reduce the entire waiting-time consumed power. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an explanatory diagram showing a power circuit in accordance with Embodiment 1 of the present invention. 
     FIG. 2 is an explanatory diagram showing a power circuit in accordance with Embodiment 2 of the present invention. 
     FIG. 3 is an explanatory diagram showing a conventional power circuit. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is directed to a structure in which a connection is made such that power is supplied from electric charge storing means to an infrared ray receiving circuit and a microcomputer, a fluctuation of voltage across the electric charge storing means is detected by voltage detecting means, and an output signal from the voltage detecting means allows an AC-DC converter to operate. 
     FIG. 1 is a diagram showing a power circuit in accordance with Embodiment I of the present invention. An AC input is connected with an AC-DC converter  101  through a switch  107 , and an output of the AC-DC converter  101  is supplied to a positive power supply of a main microcomputer  102 . The output of the AC-DC converter  101  is also supplied through a diode  116  to a sub-microcomputer  104 , an infrared ray receiving circuit  103  and a positive power supply of electric charge storing means  106 . The positive power supply is monitored in voltage by voltage detecting means  105  and an output of the voltage detecting means  105  is used for an open/close signal of the switch  107 . The infrared ray receiving circuit  103  receives an infrared ray signal  115  from the external to output an output  110 , and the output signal is inputted to the main microcomputer  102  and the sub-microcomputer  104 . A signal  111  from the sub-microcomputer  104  is used to close the switch  107 . The signal  111  is also inputted to the main microcomputer  102  through a delay circuit  112 . Output signals  113  and  117  of the main microcomputer  102  are inputted to the sub-microcomputer  104 . Also, a signal  118  used for opening the switch  107  is outputted from the sub-microcomputer  104 . 
     Subsequently, the operation of the circuit shown in FIG. 1 will be described. When the AC-DC converter  101  suspends in a state where the switch  107  is opened, the main microcomputer  102  suspends because a power is not supplied to the main microcomputer  102 . If the electric charge storing means  106  is lower than a given voltage, the voltage detecting means  105  outputs a signal which allows the switch  107  to be closed. As a result, the AC-DC converter  101  operates to charge the electric charge storing means  106 . At the same time, since the power is also supplied to the infrared ray receiving circuit  103  and the sub-microcomputer  104 , those circuits are operational. Thereafter, when the electric charge storing Weans  106  is charged up to the given voltage, the output of the voltage detecting means  105  is inverted to open the switch  107 , to thereby stop the AD-DC converter. However, in this situation, since the power is supplied to the infrared ray receiving circuit  103  and the sub-microcomputer  104  from the electric charge storing means  106 , the infrared ray receiving circuit  103  and the sub-microcomputer  104  continue to operate. 
     Now, when an infrared ray signal  115  corresponding to a command code representative of power on is input to the infrared ray receiving circuit  103  from a remote controller, the infrared ray receiving circuit  103  outputs the signal  110  to the sub-microcomputer  104 . Because the sub-microcomputer  104  is operational, the signal  111  is output to the switch  107  to make the switch  107  close. In this situation, the AC-DC converter  101  starts to operate. A voltage developed by the AC-DC converter  101  brings the main microcomputer  102  to a state where it can start to operate. Actually, a signal resulting from delaying the signal  111  by the delay circuit  112  makes the main microcomputer  102  start to operate. Actually, a signal resulting from delaying the signal  111  by the delay circuit  112  makes the main microcomputer  102  start to operate. The delay circuit is used to cancel the reset of the main microcomputer  102 , after the AC-DC converter  101  is started and its output voltage sufficiently rises. In addition, the main microcomputer  102  may output the signal  117  to the sub-microcomputer  104  after starting so as to stop the operation of the sub-microcomputer  104  for the purpose of reducing the consumed current of the sub-microcomputer. In this event, because there is found such a fact that the main microcomputer  102  normally starts to operate, the power circuit is improved in reliability. However, in the case where the consumed current of the sub-microcomputer  104  is so small that it can be ignored, the sub-microcomputer  104  may not forcedly be suspended. After the main microcomputer  102  starts operation, the infrared ray signal  115  is amplified and filtered by the infrared ray receiving circuit  103 , and then processed by the main microcomputer  102  as the signal  110 . 
     Subsequently, when the infrared ray signal  115  corresponding to a command code representative of power off is input to the infrared ray receiving circuit  103  from the remote controller, the infrared ray receiving circuit  103  outputs the signal  110  to the main microcomputer  102 . The main microcomputer  102  outputs the signal  113  to the sub-microcomputer  104  to start the operation of the sub-microcomputer  104 . After the sub-microcomputer  104  normally starts its operation, the sub-microcomputer  104  sends out the signal  118  to the switch  107 , to thereby open the switch  107 . In this method, because of the fact that the sub-microcomputer  104  normally starts to operate, the power circuit is improved in reliability. Then, because the AC-DC converter  101  suspends so that the power supply to the main microcomputer  102  is interrupted, the operation of the main microcomputer  102  also suspends with the result that the consumed power is reduced. The charges in the electric charge storing means  106  do not inversely flow to the main microcomputer  102  because of the diode  116 . 
     According to the present invention, because the power is always supplied to the infrared ray receiving circuit  103  and the sub-microcomputer  104  from the electric charge storing means  106 , the infrared ray signal  115  can always receive remote commands even in a state where the AC-DC converter  101  does not operate. In this state, because only the infrared ray receiving circuit  103 , the sub-microcomputer  104  and the voltage detecting means  105  operate, the entire consumed current can be reduced. Because the main microcomputer  102  is normally operated with clocks of about 10 MHz, a current of about 50 mA is required. However, if the structure is made so that only the sub-microcomputer  104  operates, the consumed current can be reduced to about 100 μA. Also, a total consumed current of the infrared ray receiving circuit and the voltage detecting means  105  is also reduced to about 100 μA. 
     Also, the AC-DC converter  101  is operated only when the voltage across the electric charge storing means becomes lower than the given voltage. The intermittent operation of the AC-DC converter  101  makes it possible to further reduce the consumed power in the AC-DC converter  101 . In this example, the above given voltage at which the AC-DC converter  101  operates is detected by the voltage detecting means  105 , and the given voltage is a voltage close to the lowest operating voltage of the infrared ray receiving circuit  103  or the sub-microcomputer  104 . On the other hand, in the case where the AC-DC converter  101  stops the operation after that, if the voltage across the electric charge storing means  106  rises due to charging and comes to a voltage close to the highest operating voltage of the infrared ray receiving circuit  103  or the sub-microcomputer  104 , the given voltage is detected by inverting the output of the voltage detecting means  105 . In other words, the detection of the given voltage is realized by providing the voltage detecting means  105  with hysteresis. Also the voltage detection may be conducted by the sub-microcomputer if the sub-microcomputer  104  has an A/D converter. 
     According to the present invention, the switch is used as means for stopping the operation of the AC-DC converter. Alternatively, the AC-DC converter per se may be provided with an on/oft function to realize the operation start/suspension of the AC/DC converter. 
     Also, the circuit pertaining to the infrared ray reception according to the present invention is generally supplied as a so-called module which results from mounting an IC circuit on a printed circuit board in a package state or in a bear chip state. This is called an “infrared ray receiving module”. The power circuit of the present invention is also applicable to the infrared ray receiving module. In other words, the control means, the infrared ray receiving means, the control means such as a sub-microcomputer or the main microcomputer, the voltage detecting means and the electric charge storing means are disposed on the same printed board, thereby making it possible to manufacture an infrared ray receiving module small in space. It is desirable that the A respective means are disposed on the printed board if necessary because of the arrangement of other circuits. 
     FIG. 2 is a diagram showing a power circuit in accordance with Embodiment 2 of the present invention. An AC input is connected with a first AC-DC converter  101  through a switch  107 , and an output of the AC-DC converter  101  is if supplied to a positive power supply of a main microcomputer  102 . The AC input is also connected with a second AC-DC converter  109  through a switch  108 , and an output of the AC-DC converter  109  is supplied to a sub-microcomputer  104 , an infrared ray receiving circuit  103  and a positive power supply of electric charge storing means  106 . The electric charge storing means  106  is monitored by voltage detecting means  105 , and an output of the voltage detecting means  105  is used as an open/close signal of the switch  108 . The infrared ray receiving circuit  103  receives an external to output an output  110 , and the output signal is input to the main microcomputer  102  and the sub-microcomputer  104 . A signal  111  is output from the sub-microcomputer  104  to close the switch  107 . The signal  111  is also input to the main microcomputer  102  through a delay circuit  112 . An output signal  113  of the main microcomputer  102  is input to the sub-microcomputer  104  and also used for opening the switch  107  through a delay circuit  114 . 
     Subsequently, the operation of the circuit shown in FIG. 2 will be described. When the AC-DC converter  101  suspends in a state where the switch  107  is opened, the main microcomputer  102  suspends because [a] power is not supplied to the main microcomputer  102 . If the electric charge storing means  106  is lower than a given voltage, the voltage detecting means  105  outputs a signal which allows the switch  108  is be closed. As a result, the AC-DC converter  109  operates to charge the electric charge storing means  106 . At the same time, since the power is also supplied to the infrared ray receiving circuit  103  and the sub-microcomputer  104 , those circuits are operational. Thereafter, when the electric charge storing means is charged up to the given voltage, the output of the voltage detecting means  105  is inverted to open the switch  108 , to thereby stop the AD-DC converter. However, in this situation, since the power is supplied to the infrared ray receiving circuit  103  and the sub-microcomputer  104  from the electric charge storing means  106 , the infrared ray receiving circuit  103  and the sub-microcomputer  104  continue to operate. 
     Now, when an infrared ray signal  115  corresponding to a common code representative of power on is input to the infrared ray receiving circuit  103  from a remote controller, the infrared ray receiving circuit  103  outputs the signal  110  to the sub-microcomputer  104 . Because the sub-microcomputer  104  is operational, the signal  111  is output to the switch  107  to make the switch  107  close. In this situation, the AC-DC converter  101  starts to operate. A voltage developed by the AC-DC converter  101  brings the main microcomputer  102  to a state where it can start to operate. Actually, a signal resulting from delaying the signal  111  by the delay circuit  112  makes the main microcomputer  102  start to operate. A control program may be designed in such a manner that the sub microcomputer  104  stops operation after it outputs the signal  111 , to thereby reduce the consumed power. After the main microcomputer  102  starts operating, the infrared ray signal is amplified and filtered by the infrared ray receiving circuit  103 , and then processed by the main microcomputer  102  the signal  110 . Subsequently, when the infrared ray signal  115  corresponding to a command code representative of power off is input to the infrared ray receiving circuit  103  from the remote controller, the infrared ray receiving circuit  103  from the remote controller, the infrared ray receiving circuit  103  outputs the signal  110  to the main microcomputer  102 . The main microcomputer  102  outputs the signal  113  to the sub-microcomputer  104  to start the operation of the sub-microcomputer  104 . At the same time, the signal  113  is delayed by the delay circuit  114  and is used to open the switch  107 . As a result, because the AC-DC converter  101  suspends so that the power supply to the main microcomputer  102  is interrupted, the operation of the main microcomputer  102  also suspends to reduce the consumed power. 
     According to the present invention, because the power is always supplied to the infrared ray receiving circuit  103  and the sub-microcomputer  104  from the electric charge storing means  106 , the infrared ray signal  115  can always be received even in a state where the AC-DC converters  101  and  109  do not operate. In this state, because only the infrared ray receiving circuit  103 , the sub-microcomputer  104  and the voltage detecting means  105  operate, the entire consumed current can be reduced. Because the main microcomputer  102  is normally operated with clocks of about 10 MHz, a current of about 50 mA is required. However, if the structure is made so that only the sub-microcomputer  104  operates, the consumed current can be reduced to about 100 μA. Also, a total consumed current of the infrared ray receiving circuit and the voltage detecting means  105  is also reduced to about 100 μA. The reason why the AC-DC converter is divided into converters  101  and  109  is that although the load current of the AC-DC converter  101  is on the order of several tens of A because it is used to operate the main circuit, the load current of the AC-DC converter  109  is the order of several hundreds of mA which is low in load because it is used to operate only the infrared ray receiving circuit  103 , the sub-microcomputer  104  and the voltage detecting means  105 . Accordingly, because those AC-DC converters  101  and  109  are greatly different in the order of load current from each other, if they are structured by one AC-DC converter, the efficiency at a low load is deteriorated. As a result, not only the consumed current of the infrared ray receiving circuit  103 , the sub-microcomputer  104  and the voltage detecting means  105  but also the consumed current of the AC-DC converter dominates, resulting in a factor that prevents the reduction of consumed current. For the above reason, this embodiment employs two AC-DC converters. 
     Also, the AC-DC converter  109  is operated only when the voltage across the electric charge storing means becomes lower than the given voltage. The intermittent operation of the AC-DC converter  109  makes it possible to further reduce the consumed power in the AC-DC converter  109 . In this example, the above given voltage at which the AC-DC converter  109  operates is detected by the voltage detecting means  105 , and the given voltage is a voltage close to the lowest operating voltage of the infrared ray receiving circuit  103  or the sub-microcomputer  104 . On the other hand, in the case where the AC-DC converter  109  stops the operation after that, if the voltage across the electric charge storing means rises due to charging and comes to a voltage close to the highest operating voltage of the infrared ray receiving circuit or the sub-microcomputer, the given voltage is detected by inverting the output of the voltage detecting means  105 . In other words, the detection of the given voltage is realized by providing the voltage detecting means  105  with hysteresis. Also, the voltage detection may be conducted by the sub-microcomputer if the sub-microcomputer  104  has an A/D converter. 
     According to the present invention, the switch is used as means for suspending the operation of the AC-DC converter. Alternatively, the AC-DC converter per se may be provided with an on/off function to realize the operation start/suspension of the AC/DC converter. 
     The present invention has the following advantages. That is, electricity is stored in electric charge storing means such as a secondary battery or an electric double layer capacitor so as to supply power to the microcomputer and the infrared ray receiving circuit without always operating the AC-DC converter. With the above operation, the operating frequency of the AC-DC converter is reduced so that the power consumed by the AC-DC converter which is the worst in power efficiency is reduced, thereby making it possible to reduce the entire waiting-time consumed power. Also, if the power circuit of the present invention is also applicable to the infrared ray receiving module, the control means, the infrared ray receiving means, the control means such as a sub-microcomputer and the main microcomputer, the voltage detecting means and the electric charge storing means are disposed on the same printed circuit board, thereby making it possible to manufacture the infrared ray receiving module small in space.