Abstract:
An apparatus and method for allowing a mobile device with a dead battery to be charged by another mobile device with a charged battery. The apparatus and method further provide for the prevention of damage to the batteries due to overcurrents that may occur due to battery voltage differences. Light emitting diodes are also provided to indicate the state of the charging device.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to an apparatus for charging a battery of a first mobile device from a battery of a second mobile device without causing damage to these devices due to an overcurrent. 
     2. Background of the Related Art 
     Mobile devices, such as cellular phones, are gaining in popularity with consumers. Mobile devices are not completely reliant on an electrical outlet for operation. At times, mobile devices operate using power from a battery. This allows a user to use the mobile device without being restricted to the proximity of an electrical outlet. This aspect of mobile devices is attractive, as users can operate their mobile devices while they travel and are not bound to a single location. 
     Unfortunately, the inevitable problem with mobile devices, the battery runs out of power. When this occurs, the user is unable to operate their mobile device until the user has the opportunity to connect the mobile device to an electrical outlet through a charger. This aspect of mobile devices can be quite frustrating for users. This frustration is amplified by the increase in dependence of users on their mobile devices. Accordingly, if a mobile device will not operate due to a low battery, the productivity of an individual using the mobile device may cease or be compromised. Additional features are now being incorporated into mobile devices. For instance, mobile devices may have internet browsers, email capabilities, video games, and other software and telecommunication applications. Accordingly, these applications can run down the battery of the mobile device and the problem of a disabled mobile device due to low battery becomes more prevalent. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to at least overcome the disadvantages, discussed above, of the background art. In general, the present invention enables a mobile device with a low battery to be charged or run off of another mobile device which has sufficient battery power. Embodiments of the present invention electrically couple these two mobile devices and prevent damage from occurring to the mobile devices during this battery power transfer. 
     The advantages of the present invention can be easily appreciated. For example, a first user is expecting an important telephone call on their cellular phone. If the first user does not have access to an electrical outlet and the battery in their cellular telephone is dead, then the user will not be able to receive their important telephone call. However, in accordance with the methods and apparatuses of the present invention, the user may be able to charge their cellular phone off of a colleague&#39;s cellular phone or PDA so the user can receive the important telephone call. 
     Embodiments of the present invention relate to an apparatus. The apparatus includes a first connector and a second connector. The first connector is configured to receive battery power from a first mobile device. The second connector is configured to selectively transmit battery power to a second mobile device. Similar embodiments of the present invention relate to a method. The method comprises receiving a first connector battery power from a first mobile device and selectively transmitting a second connector battery power to a second mobile device. Aspects of the present invention are advantageous, as these embodiments of the present invention prevent damage to the mobile devices by selectively transmitting battery power to avoid overcurrents. 
     In embodiments of the present invention, at least one of the first mobile device and the second mobile device is a cellular phone. In other embodiments, the apparatus includes circuitry that prevents the second connector from transmitting battery power having an overcurrent. 
     In embodiments, a regulator, a comparator, and a transistor are utilized. In some embodiments, the regulator is a low drop out regulator and the transistor is a p-channel field effect transistor. The negative terminal of the first connector may be electrically coupled to a negative terminal of the second connector. The positive terminal of the first connector may be electrically coupled to an input terminal of the regulator. The positive terminal on the first connector may also be electrically coupled to a source input of the transistor. An output terminal of the regulator may be electrically coupled to a first input of a comparator. An output terminal of the comparator may be electrically coupled to a gate input of a transistor. A drain output of the transistor may be electrically coupled to a positive terminal of the second connector. The drain output of the transistor may be electrically coupled to the second input of the comparator. The positive terminal of the second connector may be electrically coupled to the second input of the comparator. 
     In embodiments of the present invention, the regulator is configured to input an electrical power signal from the first connector. The regulator also limits the voltage level of the electrical power signal to a predetermined voltage. The regulator then outputs a limited electrical power signal. In embodiments of the present invention a predetermined voltage is 2.5 volts. In embodiments of the present invention the comparator is configured to input the limited electrical power signal at the first input of the comparator. The comparator inputs an electrical power signal from the second connector at the second input of the comparator. The comparator will output a low signal from the output terminal of the comparator if the limited electrical power signal has a higher voltage level than the electrical power signal from the second connector. The comparator will output a high signal from the output signal of the comparator if the limited electrical power signal is a lower voltage level than the electrical power signal from the second connector. Accordingly, a low signal input into the drain input of the transistor enables the second connector to transmit battery power. Likewise, a high signal input into the drain input of the transistor disables the second connector from transmitting battery power. 
     In embodiments of the present invention the output of the regulator is electrically coupled to a first light emitting diode and the output terminal of the comparator is electrically coupled to a second light emitting diode. In other embodiments of the present invention the negative terminal of the second connector, the negative terminal of the first connector, the first light emitting diode, and the second light emitting diode are electrically coupled together. 
     Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described in detail with reference to the following drawings in which like reference numerals refer to like elements wherein: 
         FIGS. 1 and 2  illustrate an apparatus for charging a mobile device. 
         FIG. 3  illustrates a DC jack of a mobile device. 
         FIG. 4  is a block diagram illustrating a PTP charging plug. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1  illustrates an apparatus for charging a mobile device. The apparatus may be a power outlet charger  11 , hands-free kit  12 , travel charger  13  or cigarette lighter charger  14 . The power outlet charger  11  has limited mobility since it receives power from an electrical outlet (i.e., 220V or 110V). The size of the power outlet charger  11  relatively large. Accordingly, the power outlet charger  11  typically stationary in offices or homes. The travel charger  13  is similar to the power outlet charger  11  in that it receives a power from an electrical outlet (220V or 110V). However, the travel charger  13  is smaller than the power outlet charger  11  and can be conveniently carried. The cigarette lighter charger  14  receives power through a cigarette lighter jack of an automobile. The hands-free kit  12  has a sound amplifier function so a user can use a mobile device hands-free. The hands-free kit  12  are typical for cellular phones and receive power from an electrical outlet or from a battery of an automobile. 
       FIG. 2  illustrates an apparatus for charging a cellular phone in accordance with embodiments of the present invention. The apparatus includes a charged cellular phone  400 , a discharged cellular phone  500 , and phone to phone charging plugs  100 ,  200  and  300  (hereinafter, as ‘PTP charging plug’). PTP charging plugs supply power by connecting a jack of the charged cellular phone  400  and the a jack of the discharged cellular phone  500 . 
       FIG. 3  illustrates a DC jack of a cellular phone in accordance with embodiments of the present invention. The cellular phones  400  and  500  include a DC jack  30  which is compatible with the charging jacks  200  and  300 . The cellular phones  400  and  500  further include a jack detection unit  40  for detecting whether the charging jacks  200  and  300  are inserted. The jack detection unit  40  transmits a detected signal to a mobile station modem chipset (hereinafter, as ‘MSM’, not shown). The jack detection unit  40  is configured to detect whether the charging jacks  200  and  300  are inserted by connecting or disconnecting pin  2  and pin  1  of the DC jack  30 . If the charging jacks  200  and  300  are not inserted, pin  2  and pin  1  are connected and the jack detection terminal  20  transmits a ground connection signal (a low level signal) to the MSM. Likewise, if the charging jacks  200  and  300  are inserted, the pin  2  and pin  1  are not connected and the jack detection terminal  20  transmits a Vcc signal (a high level signal) to the MSM. Accordingly, the MSM controls a cellular phone by detecting whether the charging jacks  200  and  300  are inserted in the DC jack  30 . 
       FIG. 4  is a block diagram illustrating a PTP charging plug. The PTP charging plug includes a first charging jack  200 , a second charging jack  300 , and a protection circuit  100 . The first charging jack  200  is connected to the charged cellular phone  400 . The second charging jack  300  is connected to the discharged cellular phone  500 . The protection circuit  100  is positioned between the first charging jack  200  and the second charging jack  300 . The protection circuit  100  is configured to intercept an overcurrent which flows to the discharged cellular phone  500  through the first charging jack  200 . 
     The protection circuit  100  includes a low drop out regulator  110 . The low drop out regulator  110  outputs a signal which is limited in magnitude to a reference voltage. The positive terminal voltage of the first charging jack  200  is input (Vin) into the low drop out regulator  110 . The positive terminal voltage is limited by the low drop out regulator  110  and then output (Vout) to comparator  120 . The comparator  120  is configured to output a low level signal if the battery voltage of the discharged cellular phone  500  is higher than the voltage of the output signal of the low drop out regulator  110 . The comparator  120  outputs a high level signal if the battery voltage of the discharged cellular phone  500  is lower than the output signal of the low drop out regulator  110 . The outputting of the low level signal and the high level signal are accomplished by comparing the voltage of the output signal of the low drop out regulator  110  and the battery voltage of the discharged cellular phone  500  at the positive input and the negative input of the comparator  120 . 
     A dual light emitting diode (LED)  140  is also included in the protection circuit  100 . In embodiments, the LED  140  includes a green LED and a red LED. The green LED includes an anode that is connected to the output terminal of the comparator  120 . The cathode of the green LED is connected to the negative power source of the charging plug. The red LED&#39;s anode is connected to the output terminal of the low drop out regulator  110 . The cathode of the red LED is connected to the negative power source of the charging plug. 
     The protection circuit  100  further includes a p-channel field effect transistor (FET)  130  for controlling the transmission of power from the charged cellular phone  400  to the discharged cellular phone  500 . The output of the comparator  120  is connected to the gate of FET  130 . Accordingly, if the output of the comparator  120  is a low level signal, power will be transmitted between the charging cellular phone  400  and the discharging cellular phone  500 . This is made possible by the positive power source of the charged cellular phone  400  being connected to the source of FET  130  and the positive power source of the charging plug of the discharged cellular phone  500  being connected to the drain of the FET  130 . 
     When the first charging jack  200  is inserted in the DC jack  30  of the cellular phone  400 , the low drop out regulator  110  checks the positive terminal voltage of the first charging jack  200 . The low drop out regulator  110  outputs a signal of the reference voltage (i.e., 2.5V) if the positive terminal voltage of the first charging jack  200  is higher than the reference voltage. The low drop out regulator  110  outputs the positive terminal voltage of the first charging jack  200  if the positive terminal voltage of the first charging jack  200  is lower than the reference voltage. This is accomplished by the low drop out regulator  110  checking the positive terminal voltage of the first charging jack  200  which is connected at Vin. Since the positive terminal of the first charging jack  200  is connected with the positive terminal of the battery of the charged cellular phone  400 , the signal which the low drop out regulator  110  actually outputs is a signal of the reference voltage. 
     The output signal of the low drop out regulator  110  is applied to the positive input terminal of the comparator  120 . The positive power source of the second charging jack (the positive terminal voltage of the cellular phone  500  battery) is applied to the negative input terminal of the comparator  120 . The comparator  120  outputs a high level signal if the voltage of the positive input terminal is higher than the negative terminal. The comparator  120  outputs a low level signal if the voltage of the positive input terminal is lower than the negative terminal. This is accomplished by the comparator  120  comparing voltages of the positive input terminal and negative input terminal. The output signal of the comparator  120  is applied to the gate of FET  130 . 
     If the level of the signal which is applied to the gate of FET  130  is low, a channel is formed between the source and drain of FET  130  and a conductive state is formed in the FET  130 . Consequently, the power of the cellular phone  400  is supplied to the cellular phone  500  through the PTP charging plug. Likewise, if the level of the signal which is applied to the gate FET  130  is high, a channel is not formed between the source and drain FET  130  and the power from cellular phone  400  is not supplied to the cellular phone  500 . 
     For example, the voltage of the cellular phone  500  battery is 2.6 volt to 4.5 volt, the voltage of the negative input terminal of the comparator  120  is higher than the voltage of the positive input terminal (lower than 2.5 volt), and the reference voltage is 2.5 volts. In this example, the comparator  120  outputs a low level signal, the state of FET  130  becomes conductive, and the battery of cellular phone  500  is charged. However, if the voltage of the cellular phone  500  battery is lower than 2.4 volt, the comparator  120  outputs a high level signal, and FET  130  is non-conductive. Accordingly, the power of the cellular phone  400  is not supplied to the cellular phone  500 . In other words, if the voltage of the cellular phone  400  battery is lower than 2.5 volt, voltage difference between batteries of the cellular phones  400  and  500  becomes larger. Accordingly, an overcurrent would flow in the PTP charging plug. The protection circuit  100  intercepts this overcurrent and prevents damage to the battery of the cellular phone  500 . 
     The dual LED  140  in the protection circuit  100  displays the charging state of the cellular phone  500 . For example, the dual LED  140  includes a red LED and green LED. When the red LED and green LED are both turned on, this is an indication that the operation of the charging apparatus is normal. The anode (positive terminal) of the green LED is connected to the output terminal of the comparator  120 . The cathode (negative terminal) of the green LED is connected to the negative power source of the charging plug. The anode of the red LED is connected with the output terminal of the low drop out regulator  110 . The cathode of the red LED is connected to the negative power source of the charging plug. Since the red LED is always on if the cellular phone is not completely discharged, the user can recognize the operation state of the charging apparatus according to the ‘on-off’ condition of the green LED. 
     The cellular phone may include both an I/O connector and DC jack  30  or just the I/O connector. The apparatus for charging the cellular phone in accordance with the present invention may be embodied by connecting with the I/O connector. The jack detection unit  40  shown in  FIG. 3 , may not be included in all cellular phones. Embodiments of the present invention include the jack detection unit  40 . Accordingly, the MSM (not shown) can control the operation which is related with cellular phone charging. Embodiments of the present invention can be applied to cellular phones which do not include the jack detection unit  40 . 
     Embodiments of the present invention relate to an apparatus including a charged cellular phone  400 , a discharged cellular phone  500 , a first charging jack  200  which is connected to the charged cellular phone  400 , a second charging jack  300  which is connected to the discharged cellular phone  500 , and a protection circuit  100  which is positioned between the first and second charging jacks  200  and  500 , for intercepting an overcurrent which flows to the discharged cellular phone  500  through the first charging jack  200 . The protection circuit includes a low drop out regulator  110  which outputs a signal which is below a reference voltage by setting a + terminal voltage of the first charging jack  200  as an input voltage, a comparator  120  for comparing a voltage of an output signal of the low drop out regulator  110  and a battery voltage of the discharged cellular phone  500  and a P channel FET  130  for controlling the conductive state by connecting a gate to the output terminal of the comparator  120 , connecting a source to the first charging jack  200  and connecting a drain to the second charging jack  300 . 
     Embodiments of the present invention relate to a method for charging a cellular phone in accordance with the present invention, including the steps of connecting a first jack  200  of a charging plug to a charged cellular phone  400 , connecting a second jack  300  of a charging plug to a discharged cellular phone  500  and supplying a power of a charged cellular phone  400  to a discharged cellular phone  500  through the charging plug. The step of supplying a power further includes a step of intercepting an overcurrent which flows to the discharged cellular phone  500  by the charging plug. Also, the step of intercepting the overcurrent further includes the steps of dropping a voltage for outputting a signal of a reference voltage in case the voltage of the + terminal of the first jack  200  is higher than the reference voltage, and outputting a signal of the corresponding input voltage in case the input voltage is lower than the reference voltage, comparing voltage for outputting a lower level signal in case the battery voltage of the discharged cellular phone is higher, and outputting a high level signal in case the battery voltage of the discharged cellular phone  500  is lower, by comparing the output signal voltage and the battery voltage of the discharged cellular phone  500  in the voltage dropping step and supplying a power to the discharged cellular phone  500  in case the level of the output signal in the step of comparing voltage is low and intercepting supply of the power to the discharged cellular phone  500  in case the level of the output signal in the step of comparing voltage is high. 
     As described above, the apparatus for charging the cellular phone in accordance with the present invention can cope with unexpected cellular phone discharging. Particularly, the present invention is accomplished by enabling charging between cellular phones. The apparatus can be conveniently carried. Damage to the battery of the cellular phone can be prevented since the apparatus contains a protection circuit. 
     The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. The description of the present invention is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art.