Patent Application
20120257426
1. Field of Invention
The present invention relates generally to alternating current adapters. More specifically, the present invention relates to an electrical adapter that converts alternating current to direct current and outputs through a coaxial plug to charge an electronic device such as a notebook computer.
2. Description of Related Art
Most modern electronic devices consume substantial amount of electrical energy to perform its complex and multiple functions. The electrical energy is generally provided by a battery enclosed within the electronic device. The battery may be a disposable battery but more commonly, it is a rechargeable battery. The rechargeable battery must be recharged with a direct current source when it is depleted.
Adapters are commonly used to convert household 110V alternating current to direct current to power and recharge electronic devices. The rechargeable battery in an electronic device is recharged by electrically connecting it to the direct current output of the adapter. The adapters are often left connected to the alternating current source even when it is not being used to recharge a rechargeable battery. Although the adapter is not being used to recharge a rechargeable battery, it nevertheless still consumes electrical power while being connected to the alternating current source. The user must either manually unplug the adapter from the alternating current source or activate a manual switch to completely shut off the consumption of electrical power by the adapter.
Additionally, when the electronic device has finished charging its rechargeable battery, yet remains connected to the adapter, the adapter continues to attempt to charge the electronic device and consume electrical power.
Therefore, there exists an unfulfilled need to be able to conveniently eliminate this constant waste of electrical power by the adapter. A convenient means, particularly one that functions automatically without requiring any manual intervention from the user, is lacking to easily conserve the electrical power that is being wasted by the adapter.
The present invention is a convenient and automatic means to automatically and completely shut off the electrical power consumption by an alternating current (AC) to direct current (DC) adapter when it is not being used to recharge an electronic device. The AC adapter with automatic built in power switch may remain plugged into an alternating current source yet consumes no power when no electronic device is connected to it or when the electronic device that is connected to it has finished charging.
The AC adapter with automatic built in power switch comprises of an AC power supply circuit, an AC control circuit, and a monitoring circuit. The monitoring circuit further comprises of a standby power supply, a microcontroller, a circuit for device detection, and a current monitor circuit. The AC power supply circuit is electrically connected to the alternating current source and converts the alternating current to direct current for charging the rechargeable battery of an electronic device. The AC control circuit, a solid state relay, acts as a switch to turn the AC power supply on and off. The monitor circuit detects whether an electronic device is connected to the adapter and also whether the charging process is completed.
a shows the complete schematic, with the components identified with labels, of the preferred embodiment of the AC adapter with automatic built-in power switch.
b shows the same complete schematic, with the values of the components identified, of the preferred embodiment of the AC adapter with automatic built-in power switch.
The following description and figures are meant to be illustrative only and not limiting. Other embodiments of this invention will be apparent to those of ordinary skill in the art in view of this description.
a and 1b show the complete schematic of the preferred embodiment of the AC adapter with automatic built-in power switch. The AC adapter with automatic built-in power switch comprises of an alternating current (AC) power supply circuit, an AC control circuit, and a monitoring circuit. The monitoring circuit further comprises of a standby power supply, a microcontroller, a circuit for device detection, and a current monitor circuit.
The type of AC power supply as illustrated in
When the AC power is off (the TRIAC Q1 is turned off), D5-1 and D5-3 will be at zero volt potential. The voltage will also be zero at the cathode of D9. R27 will pull-up the +V line to VCC (+3V). If the ground return of U3 and R24 were not disconnected, the +V voltage would be loaded by the DC resistance path of R11, R23, R25, R24, and U3 to ground. This would load the /DET signal to near zero volts. To prevent this, the gate of FET Q3 is connected via R29 to D9 cathode which is at zero volts. This turns off the FET (Q3) and lifts the ground from U3-3 and R24.
When a device is connected to the barrel plug (coaxial connector), R27 (100K) is easily loaded to ground by the device load. This makes /DET low and the MCU wakes up. The MCU then sets TON to 1 which turns on U4 which in turn triggers the TRIAC and the AC power is turned on. The transformer output is activated. D9 rectifies the pulses from T1 pins 5 and 6 which result in approximately 19V DC at R29 input. R36 divides this voltage in half to protect and turn on the FET. When the FET turns on, it grounds U3-3 and R24 which allows the normal regulator feedback loop to operate and the output to produce 19V DC at the coaxial connector. When the output goes to 19V DC, D6 is reversed biased and /DET signal goes back to VCC which is now +5V.
When the AC is turned OFF because the device current went below the threshold (as will be explained in the following section), the coaxial output will turn off and Q3 FET will also turn off because of the lack of pulses from the transformer T1. This once again opens the voltage regulator loop. If the device is still connected to the coaxial plug, it will once again load R27 to ground and cause /DET to go low again. However, the MCU does not read the /DET line for about 5 seconds after turning the AC off. Also, it looks for a positive to zero transition to turn AC back on. This prevents the supply from cycling on and off. In order to turn AC power back on, the device needs to be unplugged and plugged back in. If it is left connected, the AC will remain off in zero power mode.
Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.
