Patent Publication Number: US-9844109-B2

Title: Infrared circuit for single battery and remote controller using the same

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to the infrared control technology, and more particularly to an infrared circuit for a single battery and a remote controller using the same. 
     Description of the Related Art 
       FIG. 1  is a circuit diagram showing a conventional device having an infrared emitting function. Referring to  FIG. 1 , the device having the infrared emitting function comprises a microcontroller  101 , an IR LED  102  and at least two serially connected batteries  103 . The microcontroller  101  has an input/output pin P 01  coupled to an anode of the IR LED  102 . The microcontroller  101  outputs a pulse signal PS to the IR LED  102  through the input/output pin P 01 . 
     In the prior art, the threshold voltage of the IR LED  102  ranges from 1.0V to 1.5V, and the ordinary battery has the voltage of about 1.5V when no load is present. A no-load voltage of an unused new battery may approach 1.65V, and the voltage of the battery continuously decreases with the use of the battery. The battery may be regarded as failed after the voltage thereof is lower than 1.0V or 0.9V. When the battery is coupled to the load, the voltage thereof is decreased with the increase of the output current, and is often decreased to the voltage between 1.1V and 1.3V when an ordinary load is applied. The voltage of one battery may be higher than or lower than a threshold voltage of an infrared emitting tube. When the voltage is higher than the threshold voltage, the exceeded voltage value is too low. Thus, the current flowing through the IR LED is smaller, thereby causing the too-short emitting distance that cannot be accepted by the user. In addition, when the battery is used for a period of time, the voltage of the battery is lower than the threshold voltage of the IR LED. At this time, the IR LED cannot emit the infrared rays. Thus, the device with the infrared emitting function typically needs at least two batteries connected in series. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide an infrared circuit for a single battery and a remote controller using the same, wherein only one single battery is used to drive an IR LED circuit having a threshold voltage equal to about a voltage of the battery. 
     In view of this, the invention provides an infrared circuit to be driven by only one single battery, which outputs a battery voltage. The infrared circuit comprises an IR LED circuit, an inductor and a microcontroller. The IR LED circuit is coupled between the battery voltage and a common voltage. The inductor is coupled between the battery voltage and the common voltage. An I/O port of the microcontroller is coupled to the inductor and the IR LED circuit. When infrared rays are emitted, the microcontroller controls the battery voltage to charge the inductor through the I/O port, and utilizes a continuous current of the inductor to force the IR LED circuit to turn on. 
     The invention further provides a remote controller comprising one single battery and an infrared circuit for the single battery. The single battery outputs a battery voltage. The infrared circuit comprises an IR LED circuit, an inductor and a microcontroller. The IR LED circuit is coupled between the battery voltage and a common voltage. The inductor is coupled between the battery voltage and the common voltage. An I/O port of the microcontroller is coupled to the inductor and the IR LED circuit. When a button is pressed down, the microcontroller controls the IR LED circuit to emit infrared rays according to the pressed button. When the infrared rays are emitted, the microcontroller controls the battery voltage to charge the inductor through the I/O port, and utilizes a continuous current of the inductor to force the IR LED circuit to turn on. 
     In the infrared circuit for the single battery and the remote controller using the same according to the preferred embodiment of the invention, the inductor comprises a first end and a second end, and the IR LED circuit comprises an anode end and a cathode end. The first end of the inductor is coupled to the battery voltage, and the second end of the inductor is coupled to the I/O port of the microcontroller. The anode end of the IR LED circuit is coupled to the I/O port of the microcontroller, and the cathode end of the IR LED circuit is coupled to the common voltage. When the infrared rays are emitted, the microcontroller controls the I/O port to output the common voltage, and then the microcontroller configures the I/O port as having high impedance, so that the energy stored in the inductor flows through the IR LED circuit. 
     In the infrared circuit for the single battery and the remote controller using the same according to the preferred embodiment of the invention, the inductor comprises a first end and a second end, and the IR LED circuit comprises an anode end and a cathode end. The first end of the inductor is coupled to the common voltage, the second end of the inductor is coupled to the I/O port of the microcontroller, the anode end of the IR LED circuit is coupled to the battery voltage, and the cathode end of the IR LED circuit is coupled to the I/O port of the microcontroller. When the infrared rays are emitted, the microcontroller controls the I/O port to output a power voltage, and then the microcontroller configures the I/O port as having high impedance, so that the energy stored in the inductor flows through the IR LED circuit. 
     In the infrared circuit for the single battery and the remote controller using the same according to the preferred embodiment of the invention, the inductor comprises a first end and a second end, and the IR LED circuit comprises an anode end and a cathode end. The first end of the inductor is coupled to the battery voltage, the second end of the inductor is coupled to the I/O port of the microcontroller, the cathode end of the IR LED circuit is coupled to the battery voltage, and the anode end of the IR LED circuit is coupled to the I/O port of the microcontroller. A common voltage end of the microcontroller is coupled to the common voltage. When the infrared rays are emitted, the microcontroller controls the I/O port to output a common voltage, and then the microcontroller configures the I/O port as having high impedance, so that the energy stored in the inductor flows through the IR LED circuit. 
     The essence of the invention is to utilize the inductor to store the energy. In addition, the current of the inductor must be continuous, thereby forcing the energy stored by the inductor to flow through the IR LED circuit. Thus, even if one single battery is used, the IR LED circuit may also be driven through the inductor. Even if the voltage of the single battery is smaller than the threshold voltage of the IR LED circuit, the IR LED circuit also can be driven through the inductor. 
     Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the present invention will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a circuit diagram showing a conventional device having an infrared emitting function. 
         FIG. 2  is a circuit diagram showing a remote controller according to a preferred embodiment of the invention. 
         FIG. 3  is a circuit diagram showing an infrared circuit  203  for one single battery according to a preferred embodiment of the invention. 
         FIG. 4  shows an operation waveform chart of the infrared circuit  203  for one single battery according to a preferred embodiment of the invention. 
         FIG. 4A  is a schematic view showing a current of the infrared circuit  203  during the time T 41  according to a preferred embodiment of the invention. 
         FIG. 4B  is a schematic view showing a current of the infrared circuit  203  during the time T 42  according to a preferred embodiment of the invention. 
         FIG. 5  is a circuit diagram showing the infrared circuit  203  for one single battery according to a preferred embodiment of the invention. 
         FIG. 6  shows an operation waveform chart of the infrared circuit  203  according to a preferred embodiment of the invention. 
         FIG. 6A  is a schematic view showing a current of the infrared circuit  203  during the time T 61  according to a preferred embodiment of the invention. 
         FIG. 6B  is a schematic view showing a current of the infrared circuit  203  during the time T 62  according to a preferred embodiment of the invention. 
         FIG. 7  is a circuit diagram showing the infrared circuit  203  for one single battery according to a preferred embodiment of the invention. 
         FIG. 8  shows an operation waveform chart of the infrared circuit  203  according to a preferred embodiment of the invention. 
         FIG. 8A  is a schematic view showing a current of the infrared circuit  203  during the time T 81  according to a preferred embodiment of the invention. 
         FIG. 8B  is a schematic view showing a current of the infrared circuit  203  during the time T 82  according to a preferred embodiment of the invention. 
         FIG. 9  is a circuit diagram showing the infrared circuit  203  for one single battery according to a preferred embodiment of the invention. 
         FIG. 10  is a detailed circuit diagram showing the infrared circuit  203  for one single battery according to a preferred embodiment of the invention. 
         FIG. 11  shows an operation waveform chart of the infrared circuit  203  of  FIG. 10  according to a preferred embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 2  is a circuit diagram showing a remote controller according to a preferred embodiment of the invention. Referring to  FIG. 2 , the remote controller comprises a button  201  or a set of buttons  201 , a single battery  202  and an infrared (IR) circuit  203  for one single battery according to the embodiment of the invention.  FIG. 3  is a circuit diagram showing the infrared circuit  203  for the one single battery according to a preferred embodiment of the invention. Referring to  FIG. 3 , the infrared circuit  203  comprises an IR light-emitting diode (LED) circuit  301 , an inductor  302  and a microcontroller  303 . In addition, for the sake of description,  FIG. 3  also shows the single battery  202  and the button  201 . The button  201  is coupled to the microcontroller  303 . An anode of the IR LED circuit  301  is coupled to an I/O port IOP of the microcontroller  303 . A cathode of the IR LED circuit  301  is coupled to a common voltage VCOM. In this embodiment, a threshold voltage of the IR LED circuit  301  is higher than a battery voltage VBAT. A first end of the inductor  302  is coupled to the battery voltage VBAT, and a second end of the inductor  302  is coupled to the I/O port IOP of the microcontroller  303 . A power source end VDD of the microcontroller  303  is coupled to the battery voltage VBAT, and the ground GND of the microcontroller  303  is coupled to the common voltage VCOM. 
       FIG. 4  shows an operation waveform chart of the infrared circuit  203  for one single battery according to a preferred embodiment of the invention. Referring to  FIG. 4 , in order to simplify the description, it is assumed that the button  201  generally outputs a series of infrared pulses when the button  201  is pressed down. For the sake of explanation in this embodiment, the infrared circuit  203  outputs one infrared pulse. A waveform  401  represents the waveform of the I/O port IOP of the microcontroller  303 ; and a waveform  402  represents a current waveform of the inductor  302 . When the button  201  is pressed down, the microcontroller  303  controls the I/O port to switch from a high impedance state to a logic low voltage. At this time, charging of the inductor  302  starts. During the time T 41 , the current of the inductor  302  linearly rises. During this time, the current IL of the inductor  302  is shown in  FIG. 4A .  FIG. 4A  is a schematic view showing a current of the infrared circuit  203  during the time T 41  according to a preferred embodiment of the invention. 
     When the I/O port IOP switches from the logic low voltage to the high impedance state, the current of the inductor  302  needs to be continuous. So, during the time T 42 , the current of the inductor  302  flows from the anode of the IR LED circuit  301  to the common voltage VCOM, and the current of the inductor  302  linearly decreases. During this time, the current IL of the inductor  302  is shown in  FIG. 4B .  FIG. 4B  is a schematic view showing a current of the infrared circuit  203  during the time T 42  according to a preferred embodiment of the invention. Thus, even if only one single battery  201  is used, the IR LED circuit  301  still can be driven to emit the infrared signal. 
       FIG. 5  is a circuit diagram showing the infrared circuit  203  for one single battery according to a preferred embodiment of the invention. Referring to  FIG. 5 , the infrared circuit  203  for one single battery comprises an IR LED circuit  501 , an inductor  502  and a microcontroller  503 , In addition, for the sake of description,  FIG. 5  further depicts the single battery  202  and the button  201 . The button  201  is coupled to the microcontroller  503 . An anode of the IR LED circuit  501  is coupled to the battery voltage VBAT, and a cathode of the IR LED circuit  501  is coupled to an I/O port IOP of the microcontroller  503 . A first end of the inductor  502  is coupled to the I/O port IOP of the microcontroller  503 , and a second end of the inductor  502  is coupled to the common voltage VCOM. A power source end VDD of the microcontroller  503  is coupled to the battery voltage VBAT, and a ground GND of the microcontroller  503  is coupled to the common voltage VCOM. 
       FIG. 6  shows an operation waveform chart of the infrared circuit  203  according to a preferred embodiment of the invention. Referring to  FIG. 6 , in order to simplify the description, it is assumed that the button  201  generally outputs a series of infrared pulses when the button  201  is pressed down. In this embodiment, for the sake of explanation, the infrared circuit  203  for one single battery outputs one infrared pulse. A waveform  601  represents a waveform of the I/O port IOP of the microcontroller  503 ; and a waveform  602  represents a current waveform of the inductor  502 . When the button  201  is pressed down, the microcontroller  503  controls the I/O port to switch from the high impedance state to the logic high voltage. At this time, charging of the inductor  502  starts, and the current linearly rises during the time T 61 . During this time, a current IL of the inductor  502  is shown in  FIG. 6A .  FIG. 6A  is a schematic view showing a current of the infrared circuit  203  during the time T 61  according to a preferred embodiment of the invention. 
     When the I/O port IOP switches from the logic high voltage to the high impedance state, the current of the inductor  502  flows from the anode of the IR LED circuit  501  to the common voltage VCOM, and the current of the inductor  502  linearly decreases during the time T 62  because the current of the inductor  502  needs to be continuous. During this time, the current IL of the inductor  502  is shown in  FIG. 6B .  FIG. 6B  is a schematic view showing a current of the infrared circuit  203  during the time T 62  according to a preferred embodiment of the invention. Thus, even if only one single battery  201  is used, the IR LED circuit  501  also can be driven to emit the infrared signal. 
       FIG. 7  is a circuit diagram showing the infrared circuit  203  for one single battery according to a preferred embodiment of the invention. Referring to  FIG. 7 , the infrared circuit  203  for one single battery comprises an IR LED circuit  701 , an inductor  702  and a microcontroller  703 . In addition, for the sake of description,  FIG. 7  further depicts the single battery  202  and the button  201 . The button  201  is coupled to the microcontroller  703 . The anode of the IR LED circuit  701  is coupled to the I/O port IOP of the microcontroller  703 , and the cathode of the IR LED circuit  701  is coupled to the battery voltage VBAT. The first end of the inductor  702  is coupled to the battery voltage VBAT, and the second end of the inductor  702  is coupled to the I/O port IOP of the microcontroller  703 . The power source end VDD of the microcontroller  703  is coupled to the battery voltage VBAT, and the ground GND of the microcontroller  703  is coupled to the common voltage VCOM. 
       FIG. 8  shows an operation waveform chart of the infrared circuit  203  according to a preferred embodiment of the invention. Referring to  FIG. 8 , in order to simplify the description, it is assumed that when the button  201  is pressed down, a series of infrared pulses are generally outputted. In this embodiment, for the sake of explanation, the infrared circuit  203  for one single battery outputs one infrared pulse. A waveform  801  represents a waveform of the I/O port IOP of the microcontroller  703 ; and a waveform  802  represents a current waveform of the inductor  702 . When the button  201  is pressed down, the microcontroller  703  controls the I/O port to switch from a high impedance state to a logic low voltage. At this time, charging of the inductor  702  starts. During the time T 81 , the current linearly rises. During this time, the current IL of the inductor  702  is shown in  FIG. 8A .  FIG. 8A  is a schematic view showing a current of the infrared circuit  203  during the time T 81  according to a preferred embodiment of the invention. 
     When the I/O port IOP switches from the logic low voltage to the high impedance state, because the current of the inductor  702  needs to be continuous, the current of the inductor  702  flows from the anode of the IR LED circuit  701  to the battery voltage VBAT, and the current of the inductor  702  linearly decreases during the time T 82 . During this time, the current IL of the inductor  702  is shown in  FIG. 8B .  FIG. 8B  is a schematic view showing a current of the infrared circuit  203  during the time T 82  according to a preferred embodiment of the invention. Thus, even if only one single battery  201  is used, the IR LED circuit  701  may also be driven to emit the infrared signal. 
     Although the above-mentioned three embodiments have different connection relationships, the inductor is utilized to store the energy and then release the energy to turn on the IR LED circuit to output the infrared rays in a basic manner. Any modification, in which the IR LED circuit is coupled between the battery voltage VBAT and the common voltage VCOM, the inductor is coupled between the battery voltage VBAT and the common voltage VCOM, the microcontroller controls the battery voltage VBAT to charge the inductor through the I/O port when infrared rays are emitted, and a continuous current of the inductor forces the IR LED circuit to turn on, is regarded as falling within the scope of the invention. So, the invention is not restricted to the above-mentioned three embodiments. 
       FIG. 9  is a circuit diagram showing the infrared circuit  203  for one single battery according to a preferred embodiment of the invention. Referring to  FIGS. 9 and 3 , the difference between the embodiments of  FIGS. 9 and 3  resides in that a microcontroller  903  in the embodiment of  FIG. 9  has no power source end VDD, and that the microcontroller  903  has a first I/O port IOP 1  and a second I/O port IOP 2 . In addition, a cathode of the IR LED  901  is coupled to the second I/O port IOP 2  of the microcontroller  903 . An inductor  902  is similarly coupled between the battery voltage VBAT and the first I/O port IOP 1  of the microcontroller  903 . In this embodiment, the microcontroller  903  receives the electric power for working through its first I/O port IOP 1 . 
       FIG. 10  is a detailed circuit diagram showing the infrared circuit  203  for one single battery according to a preferred embodiment of the invention. Referring to FIG.  10 , the inside of the dashed line is the inside of the microcontroller  903 , and the outside of the dashed line is the external circuit. In this embodiment, the microcontroller  903  has a P-type metal-oxide-semiconductor field-effect transistor (MOSFET) MP 1 , a first N-type MOSFET MN 1  and a second N-type MOSFET MN 2 , wherein the P-type MOSFET MP 1  has a parasitic diode DP 1 . 
       FIG. 11  shows an operation waveform chart of the infrared circuit  203  of  FIG. 10  according to a preferred embodiment of the invention. Referring to  FIGS. 10 and 11 , VBAT represents a battery voltage; VDDM represents a power voltage of the microcontroller  903 ; PG 1  represents a signal given to the gate of the P-type MOSFET MP 1 ; NG 1  represents a signal given to the gate of the first N-type MOSFET MN 1 ; NG 2  represents a signal given to the gate of the second N-type MOSFET MN 1 ; IL represents a current flowing through the inductor  902 ; IIR represents a current flowing through the IR LED  901 ; IMP represents a current flowing through the P-type MOSFET MP 1 ; WKUP represents a wake-up enable signal of the microcontroller  903 ; and LVRB represents a low voltage reset signal. 
     Similarly, it is assumed that the infrared circuit  203  for one single battery is an infrared ray remote controller. When no remote control operation is performed, the microcontroller  903  is in a standby state, and the operation voltage thereof only needs to be 0.9V. When the user presses the button, a wake-up signal WKUP is enabled. At this time, the gate of the first N-type MOSFET MN 1  is given with a switch signal NG 1  of the frequency of 250 KHz, and the gate of the second N-type MOSFET MN 2  is given with the logic low voltage NG 2 , so the second N-type MOSFET MN 2  is in an off state. When the first N-type MOSFET MN 1  turns off, the current of the inductor  902  charges the power voltage VDDM of the microcontroller  903  through the parasitic diode DP 1  of the P-type MOSFET MP 1 . 
     After the time T 1  has elapsed and when the power voltage of the microcontroller  903  VDDM is charged to 2.2V, waiting is performed for the time T 2 , and then the low voltage reset signal LVRB is enabled and the microcontroller  903  is reset. Thereafter, the transmission of the remote control signal of 38 KHz starts. When the transmission of the remote control signal of 38 KHz starts, the second N-type MOSFET MN 2  is turned on. At this time, the gate of the first N-type MOSFET MN 1  is given with the switch signal NG 1  of the frequency 38 KHz. Because the second N-type MOSFET MN 2  is turned on, the current of the inductor  902  flows to the IR LED  901  to emit the IR optical signal. Also, please refer to the symbol  1101 . In each period the second N-type MOSFET MN 2  is turned off, the gate of the first N-type MOSFET MN 1  is given with the switch signal NG 1  (short pulse) of the frequency 250 KHz. Thus, the inductor can charge the power voltage VDDM of the microcontroller  903 . 
     When the signal output is completed, the low voltage reset signal LVRB is switched from the logic high voltage to the logic low voltage, the switching of the switch signal NG 1  given to the gate of the first N-type MOSFET MN 1  and the switch signal NG 2  given to the second N-type MOSFET MN 2  stops, and the microcontroller  903  again returns to the standby state. 
     The more special property is that the microcontroller  903  of this embodiment does not need additional power voltage pins. The microcontroller  903  utilizes the first N-type MOSFET MN 1  inside the first I/O port IOP 1  to switch to make the inductor continuously charge/discharge, so that the microcontroller  903  can obtain the enough power voltage. In addition, the power voltage of the microcontroller  903  is again charged each time after the remote control signal of 38 KHz is transmitted in the above-mentioned embodiment. However, this implementation is only the preferred implementation. If the power voltage is stable, it is not necessary to charge the power voltage of the microcontroller  903  each time after the remote control signal of 38 KHz is transmitted. The invention is not restricted thereto. Furthermore, although the above-mentioned embodiment charges the microcontroller with the frequency of 250 KHz, those skilled in the art should know that the frequency relates to the inductance or other parameters, and is unnecessary to be kept at 250 KHz. So, the invention is not restricted thereto. Similarly, although 38 KHz is the frequency of the existing infrared receiver, the invention can also be applied to other applications. If other frequency bands are used in other applications, the invention may also be implemented at other frequencies. So, the invention is not restricted thereto. 
     In summary, the essence of the invention is to utilize the inductor to store the energy. In addition, because the current of the inductor needs to be continuous, the stored energy is forced to flow through the IR LED circuit. Thus, even if one single battery is used, the IR LED circuit also can be driven through the inductor. Even if the battery voltage of the single battery is lower than the threshold voltage of the IR LED circuit, the IR LED circuit also can be driven through the inductor. 
     While the present invention has been described by way of examples and in terms of preferred embodiments, it is to be understood that the present invention is not limited thereto. To the contrary, it is intended to cover various modifications. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications.