Abstract:
An alarm feedback circuit for alerting Smartphone users when the Smartphone internal battery is fully charged is provided. The alarm feedback circuit includes necessary circuitry sufficient to monitor the current draw of the Smartphone internal battery and provide a visual and audible alarm once the Smartphone battery is fully charged. The alarm feedback circuit is configured to be used with Smartphone chargers of the type considered to be compatible with the European Union specification for a common External Power Supply (EPS) which are used for Smartphones and adopted by the majority of the world&#39;s largest Smartphone manufacturers.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims benefit and priority of U.S. Provisional Application No. 62/069,237, Filed Oct. 27, 2014 Titled, Smartphone Charging Alarm Feedback Device, of which the entire disclosure of is incorporated by reference herein. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISK APPENDIX 
     Not Applicable 
     FIELD OF THE INVENTION 
     The present disclosure relates to a Smartphone charging alarm feedback device comprising of an alarm feedback circuit in which an alarm is activated when a Smartphone is fully charged. 
     BACKGROUND OF THE INVENTION 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     There are many known Smartphone charging devices. Most Smartphone charging devices are comprised of a small electrical outlet plug containing the Smartphone alternating current (AC) to direct current (DC) charging circuit which is connected to the Smartphone by a standard Universal Serial Bus (USB) type cable. The USB type cable can be disconnected from the AC to DC charging unit for other purposes such as using the USB type cable to connect the Smartphone to a personal computer. A good example of said charging device is the type of charger compatible with the European Union specification for a common External Power Supply (EPS) used for Smartphones. The EPS specification Smartphone charger has been adopted by the majority of the world&#39;s largest Smartphone manufacturers which are sold in countries all over the world. The Smartphone charging devices meeting this specification are configured to connect to Smartphones using a USB type cable. Said Smartphone charging devices convert AC voltage to DC voltage and provide 5 volts DC for charging the Smartphone device. 
     In recent years said Smartphone charging devices utilizing a USB type cable have become a standard for most Smartphone manufacturers. As such, Smartphone manufacturers have designed their Smartphones to utilize batteries conducive to charging with said industry standard charging devices. The USB type interface to the charging unit allows for connection to personal computers for the purpose of data transfer as well as charging the Smartphone devices while connected to the personal computer&#39;s USB port. 
     Said Smartphone charging devices utilizing a USB type cable are designed specifically for Smartphone charging without any type of Smartphone battery charge status alert to the user. Typically, when a Smartphone user charges a Smartphone the Smartphone is left unattended even after the Smartphone battery reaches a full charge due to the user not having a good indicator that the Smartphone battery is fully charged. It should be noted that most Smartphones do have a Light Emitting Diode (LED) flashing indicator built into the Smartphone itself to indicate when the battery is fully charged. However, in most cases, the user may not see this LED indicator without physically touching or activating the Smartphone and/or unless the user is in close proximity of the Smartphone. It should also be noted that said LED indicator built into the Smartphone may also be used to indicate when a Smartphone has received an email or text message in which it may be difficult for the user to discern if the phone battery is fully charged or if an email/text message has been received. 
     A need, therefore, exists for a charge status indicator in which the Smartphone user is alerted once the Smartphone battery is fully charged. More specifically, a need exists for an alarm to alert the Smartphone user once the Smartphone battery is fully charged that may be noticeable by the user from a distance and/or without having to physically touch or activate the Smartphone. 
     SUMMARY OF THE INVENTION 
     The present teaching seeks to provide an alarm feedback circuit compatible with said USB type Smartphone charging devices to alert the user when the Smartphone is fully charged. The present teaching comprises of a voltage monitoring circuit coupled with an alarm feedback circuit compatible with USB type Smartphone charging devices. Power to the circuitry of the present teaching is provided by the Smartphone charging device. The present teaching is configured to connect between the Smartphone charging unit and the Smartphone device using USB type connections. 
     The present teaching includes an audible alarm as well as a visual LED alarm used to alert the Smartphone user when the Smartphone device battery is fully charged. The audible alarm may be configured to emit a beeping sound when the Smartphone is fully charged. Similarly, the visual LED alarm may be configured to flash when the Smartphone battery is fully charged. Both the audible and visual alarms may be preset to emit their respective audible or visual alert simultaneously at an interval defined by the inventor. Both the audible and visual alarms may be configured such that the Smartphone user may be able to observe the alarms from a distance and/or without having to physically touch or activate the Smartphone. 
     The present teaching includes a user control feature such that the user may switch between audible and visual alarm or visual alarm only. This feature may be used in settings where an audible alarm may not be convenient such as at night time when the user is sleeping or when the user is in a public setting. Said user control feature may be accessible from the exterior of the invention&#39;s enclosure which houses the alarm feedback circuitry. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is a perspective view, showing a Smartphone charging device utilizing a USB type connection to a Smartphone; 
         FIG. 2  is a perspective view, showing the present invention; 
         FIG. 3  is a perspective view, showing the present invention attached to a Smartphone charging device utilizing a USB type connection to a Smartphone; 
         FIG. 4  is a block diagram of the present invention; 
         FIG. 5  is a schematic view, showing the components of the present invention with hashed lines corresponding to the block diagram. 
     
    
    
     DETAILED DESCRIPTION 
     With initial reference to  FIG. 1 , a Smartphone  10  is connected to a Smartphone charging device  30  using a standard USB Type A Male to USB Type B Male cable  20  as illustrated. The Smartphone charging device  30  may have a USB Type A Female Port  31  on the side of the Smartphone charging device  30  as illustrated. Alternately, the Smartphone charging device  30  may have a USB Type A Female Port  31  on any other surface of the device but is not illustrated. The Smartphone  10  may have a USB Type B Female Port  11  on the side of the Smartphone  10  as illustrated. Alternately, the Smartphone  10  may have a USB Type B Female Port  11  on any other surface of the Smartphone  10  but is not illustrated. 
     With reference to  FIG. 2 , the Smartphone Charging Alarm Feedback Device  40  is depicted with an attached USB Type A Male  130  cable. The USB Type A Male  130  cable may be used to connect the Smartphone Charging Alarm Feedback Device  40  to a Smartphone charging device  30  as shown in  FIG. 3 . 
     With reference to  FIG. 3 , a Smartphone  10  is depicted as being attached to the Smartphone Charging Alarm Feedback Device  40 . Referring back to  FIG. 2 , the Smartphone Charging Alarm Feedback Device  40  may include a USB Type A Female  140  connector port to connect the standard USB Type A Male to USB Type B Male cable  20 . The ideal method of attaching a Smartphone  10  to the Smartphone Charging Alarm Feedback Device  40  may be achieved using a standard USB Type A Male to USB Type B Male cable  20  whereas the USB Type A end of said cable may be connected to the USB Type A Female  140  connector port of the Smartphone Charging Alarm Feedback Device  40  and the USB Type B cable end of said cable may be connected to the USB Type B Female Port  11  of the Smartphone  10 . Referring to  FIG. 3 , the Smartphone Charging Alarm Feedback Device  40  with attached USB Type A Male  130  cable is depicted as being attached to a Smartphone charging device  30  using a USB Type A Female Port  31  as depicted in  FIG. 1 . 
     PREFERRED EMBODIMENT OF THE INVENTION 
     In a preferred embodiment of the invention, the Smartphone Charging Alarm Feedback Device  40  may be attached between the Smartphone  10  and the Smartphone charging device  30  as illustrated in  FIG. 3  and previously described. The Smartphone  10  may be connected to the Smartphone Charging Alarm Feedback Device  40  using a standard USB Type A Male to USB Type B Male cable  20 . The Smartphone Charging Alarm Feedback Device  40  may be connected to a Smartphone charging device  30  using a USB Type A Male  130  cable which may be attached internally and electrically to the Smartphone Charging Alarm Feedback Device  40 . 
     Referring now to  FIGS. 4 and 5 , the Smartphone Charging Alarm Feedback Device  40  may contain internal circuitry configured such that a Smartphone  10  may be monitored to detect when the Smartphone  10  internal battery may be fully charged. Further, the Smartphone Charging Alarm Feedback Device  40  may contain internal circuitry configured to alert the Smartphone  10  user when the battery may be fully charged. To achieve said functions, further detail will be explained in the proceeding descriptions. 
     Once the Smartphone Charging Alarm Feedback Device  40  is connected to a Smartphone  10  and Smartphone charging device  30  as shown in  FIG. 3 , a series of circuitry internal to the Smartphone Charging Alarm Feedback Device  40  may be used to detect and alert when a Smartphone  10  internal battery may be fully charged. 
       FIGS. 4 and 5  depict an Operational Amplifier Sensing Circuit  50  in series with the USB Type A Male  130  cable (supply side) and the USB Type A Female  140  connector (load side). Ohm&#39;s Law teaches us that by placing a low resistance value resistor in series with a current path produces a small voltage drop across said resistor proportional to current draw across said resistor which can serve as a measurable signal. Resistor RS in the Operational Amplifier Circuit  50  is of a low resistance value and may be used to demonstrate current draw and proportional voltage drop across resistor RS as the Smartphone  10  internal battery is charged. It should be noted that by using a resistor with a low resistance value for resistor RS may not affect the load device significantly or noticeably by the user. 
     With reference to  FIGS. 4 and 5 , demonstrating the current draw and proportional voltage drop across resistor RS may be achieved by connecting resistor RS in series with the negative voltage from the Smartphone charging device  30  going to the Smartphone  10 . The negative voltage may be passed from the Smartphone charging device  30  through the Smartphone Charging Alarm Feedback Device  40  using the USB Type A Male  130  cable on the supply side and the USB Type A Female  140  connector on the load side. To monitor the current draw and proportional voltage drop across resistor RS one may connect the load side of RS to the (+) input of operational amplifier U 3  through resistor R 1 . Similarly, the supply side of resistor RS to the Smartphone  10  may be connected to the (−) input of operational amplifier U 3  through resistor R 7 . Effectively, the supply side of resistor RS may become the ground path for the Smartphone Charging Alarm Feedback Device  40  internal circuitry and may also serve as the negative voltage source for the Smartphone  10  which may be connected to the Smartphone Charging Alarm Feedback Device  40  as previously described in  FIG. 3 . In this configuration, the output of operational amplifier U 3  may provide an output voltage equal to the voltage drop across resistor RS. By measuring the voltage drop across resistor RS, one may demonstrate that as the Smartphone  10  internal battery reaches a fully charged state, the voltage drop proportional to current draw of the Smartphone  10  internal battery across resistor RS may drop to a lower level. The voltage drop measured across resistor RS may be a small voltage measured in milli-volts. For example, when the Smartphone  10  internal battery is at a 0% charge state, the voltage drop across resistor RS may be 0.038 volts. Resistors R 1 , R 2 , R 7  and R 8  values of the Operational Amplifier Sensing Circuit  50  may be used to amplify the output of operational amplifier U 3 . The values of resistors R 1 , R 2 , R 7  and R 8  are selected such that the output of operational amplifier U 3  may be amplified by 100 times thus producing a voltage signal that may be more easily monitored to determine the point at which the Smartphone  10  internal battery may be fully charged. By measuring the output of operational amplifier U 3  configured with R 1 , R 2 , R 7  and R 8  signal amplification as previously described and shown in Operational Amplifier Sensing Circuit  50 , one may observe that as the Smartphone  10  internal battery is charged, the output may change from a higher voltage level of 3.8 volts (Smartphone  10  internal battery 0% charge state) to a lower voltage level of 2.25 volts (Smartphone  10  internal battery 100% charge state). 
       FIGS. 4 and 5  depict a an additional circuit shown as a Comparator Circuit  60  where as an operational amplifier may be configured to compare two voltage signals in which the amplified output of previously described Operational Amplifier Sensing Circuit  50  is fed into the (−) input of operational amplifier U 1 . The (+) input of operational amplifier U 1  may be configured with resistors R 11  and R 12 . The values of R 11  and R 12  may be chosen such that a reference voltage of 2.25 volts is supplied to the (+) input of operational amplifier U 1 . In the said configuration of Comparator Circuit  60 , the output of U 1  remains low until the amplified signal from Operational Amplifier Sensing Circuit  50  connected to the (−) input of operational amplifier U 1  drops to a level matching the reference voltage supplied to the (+) input using resistors R 11  and R 12 . At the point which the (−) input of operational amplifier U 1  drops to 2.25 volts matching the reference voltage applied to the (+) input using resistors R 11  and R 12 , the output of Comparator Circuit  60  may change to a high state of approximately 3.5 volts indicating that the Smartphone  10  internal battery may have reached a fully charged state. The output of U 1  may be configured with Resistor R 17  to provide stability for the output voltage. 
       FIGS. 4 and 5  depict an additional circuit shown as Comparator Circuit  70  which may be configured with Relay Circuit  80  to disable Buzzer Pulse Generator Circuit  100  which may provide the driving voltage for Audible Buzzer Circuit  110 . The purpose of Comparator Circuit  70  is to disable the output signal of Comparator Circuit  60  when the Smartphone  10  may be disconnected from the Smartphone Charging Alarm Feedback Device  40 . Further, the purpose of said circuitry may be to mute the Audible Buzzer Circuit  110  once the Smartphone  10  has reached a fully charged state and is disconnected from the Smartphone Charging Alarm Feedback Device  40  by the user. 
     To achieve previously said function of disabling the output signal of Comparator Circuit  60  and effectively muting the Audible Buzzer Circuit  60  when the Smartphone  10  may be disconnected from the Smartphone Charging Alarm Feedback Device  40  by the user; refer again to  FIGS. 4 and 5 . The output signal of U 1  in Comparator Circuit  60  may be routed through the Normally Open contacts of relay RL 1  shown in the Relay Circuit  80 . The Normally Open contacts of relay RL 1  are commonly known to remain open until a sufficient voltage may be applied to the coil of relay RL 1  causing the contacts to close and thus may be allowing a voltage signal to pass across the contacts of relay RL 1 . Thus creating a switching circuit in which a signal applied to the Normally Open contacts of relay RL 1  may be enabled or disabled. The switching action of relay RL 1  may be achieved by connecting the positive side of relay RL 1  coil to the output of Comparator Circuit  70  which may remain low or zero volts until the voltage applied to the (+) input of U 2  is equal to or greater than the reference voltage applied to the (−) input of U 2  which may cause the output to go to a high state of approximately 3.8 volts. 
     Further, to achieve previously said switching of relay RL 1 , the (+) input of U 2  is connected to the output of Operational Amplifier Sensing Circuit  50  which as previously explained produces a voltage signal relative to the charging state of the Smartphone  10  internal battery. The (−) input of U 2  is connected to resistors R 9  and R 10 . The values of resistors R 9  and R 10  may be selected to provide a reference voltage of 0.005 volts. In said configuration of Comparator Circuit  70 , the output of U 2  may remain high as long as the voltage being compared on the (+) input which is fed from Operational Amplifier Sensing Circuit  50  is greater than said reference voltage fed into the (−) input of U 2  configured with resistors R 9  and R 10 . When the output of U 2  is in a high state, one may measure 3.7 volts and one may use this voltage to control relay RL 1  as will be further explained in the following text. 
     When the Smartphone  10  is disconnected from the Smartphone Charging Alarm Feedback Device  40  by the user, the output of Operational Amplifier Sensing Circuit  50  will drop to a zero voltage state since there may be no current draw from the Smartphone  10  internal battery and no proportional voltage drop observed across resistor RS in Operational Amplifier Sensing Circuit  50  as previously explained. Thus, the output of Comparator Circuit  70  can be used to apply a low signal of zero volts to relay RL 1  coil contacts which may effectively keep the Normally Open contacts of relay RL 1  open when a Smartphone  10  is not connected to the Smartphone Charging Alarm Feedback Device  40 . Likewise, the output of Comparator Circuit  70  may be used to apply voltage to relay RL 1  coil contacts which may effectively cause the Normally Open contacts of relay RL 1  to close; thus permitting the output signal of Comparator Circuit  60  to pass thru the Normally Open contacts of relay RL 1  as previously described to the Buzzer Pulse Generator Circuit  100 . The application of voltage to relay RL 1  coil contacts may be achieved by using the output of U 2  to drive transistor Q 1  using resistors R 15  and R 16 . The values of resistors R 15  and R 16  may be selected to provide stabilization to the output of U 2  to prevent noise or voltage swings while driving transistor Q 1 . When output voltage from U 2  as previously described drives transistor Q 1 , a negative voltage or ground may be applied to the negative side of relay RL 1  coil through transistor Q 1  while a constant 5.0 volts may be applied to the positive side of relay RL 1  coil, thus energizing the coil of relay RL 1  and closing the Normally Open contacts of relay RL 1 . Therefore, in using the configuration of Comparator Circuit  70  and Relay Circuit  80  as described, it may be feasible to provide a disable function to mute the Audible Buzzer Circuit  110  which is driven by Buzzer Pulse Generator Circuit  100  when the Smartphone  10  is disconnected from the Smartphone Charging Alarm Feedback Device  40 . The functionality of the Audible Buzzer Circuit  110  and Buzzer Pulse Generator Circuit  100  will be further explained in following text. 
     Referring to  FIGS. 4 and 5 , the Buzzer Pulse Generator Circuit  110  may be activated by receiving a supply voltage of 3.7 volts on pins  4  (reset) and  8  (supply voltage) of U 4  from Comparator Circuit  60  through the Normally Open contacts of relay RL 1  in the Relay Circuit  80  as previously explained. U 4  may be an integrated circuit commonly known as a 555 timer which may be used to generate a low and high alternating output signal. The alternating low and high output signal may be used to drive an audible alarm and/or visual indicator such as a LED. 
     Pertaining to the Smartphone Charging Alarm Feedback Device  40 , the Buzzer Pulse Generator Circuit  100  which may be powered by the output of Comparator Circuit  60  may be configured with resistors R 3  and R 4  along with C 2  to generate a low and high alternating output frequency as determined by the inventor. The values of R 3 , R 4  and C 2  may be selected to give the desired low and high alternating output frequency as so desired by the inventor. The alternating output voltage low signal may be 0 volts where as the high signal may be approximately 2.4 volts. It should be noted that by changing the values of R 3 , R 4  or C 2  components, one may change the frequency of the low and high alternating output such that the transition from low to high state is faster or slower. It should also be noted that by changing the values of said components, one may change the duration of the low and high state also known as output frequency. In the described configuration, one side of resistor R 3  may be connected to 5 volts while the other side of resistor R 3  may be connected to pin  7  (discharge) of U 4 . Similarly, one side of resistor R 4  may be connected to pin  7  of U 4  while the other side of resistor R 4  may be connected to pins  2  (Trigger) and  6  (Threshold) of U 4 . Also, the positive side of polarized capacitor C 2  may be connected to pins  2  and  6  and the negative side of capacitor C 2  may be connected to ground or −5 volts. 
     Pertaining to the Smartphone Charging Alarm Feedback Device  40 , the previously described alternating low and high output signal from the Buzzer Pulse Generator Circuit  100  is fed into Transistor Q 2  to drive the Audible Buzzer Circuit  110 . The high alternating output of U 4  may be used to drive transistor Q 2  using resistors R 13  and R 18 . The values of resistors R 13  and R 18  may be selected to provide stabilization to the output of U 4  to prevent noise or voltage swings while driving transistor Q 2 . During the high output cycle of the alternating output of U 4 , transistor Q 2  may be driven to effectively provide a ground path to the negative pin of buzzer P 1  in the Audible Buzzer Circuit  110 . During the low output cycle of the alternating output of U 4 , transistor Q 2  may not be driven and effectively remains open, thus not providing a ground path to the negative pin of buzzer P 1  in the Audible Buzzer Circuit  110 . The positive side of buzzer P 1  in the Audible Buzzer Circuit  110  may receive +5 volts through switch SW 1  and resistor R 14 . Switch SW 1  may be used by the user to put the Smartphone Charging Alarm Feedback Device  40  into a silent mode whereas only the visual LED indicator  120  may function to alert the user as to the Smartphone  10  internal battery charge status. Resistor R 14  may be used to adjust the pitch and/or volume of the buzzer as defined by the inventor. With switch SW 1  in the closed position along with the alternating low and high voltage signal supplied by the output of U 4  as previously described in the Buzzer Pulse Generator Circuit  100 , the Smartphone Charging Alarm Feedback Device  40  may effectively emit an intermittent beeping sound and flashing LED to alert the user of the charge status of the Smartphone  10 . The color of said LED may be selected and/or changed as defined by the inventor. 
     The previously mentioned LED indicator  120  circuit which may be used to alert the Smartphone  10  user of the Smartphone  10  internal battery charge status may be a common LED configured with resistor R 6 . The value of resistor R 6  is selected by the inventor to determine the brightness of LED 2 . LED 2  is configured similarly to the Audible Buzzer Circuit  110  in that it may receive its ground signal via transistor Q 2  which as previously described may be driven by the output of U 4 . It should be noted that by this method, LED 2  emits a flashing light corresponding to the sound of buzzer P 1  in the Audible Buzzer Circuit  110 . Thus the Smartphone Charging Alarm Feedback Device  40  may provide the Smartphone  10  user an audible and visual alarm corresponding to the previously described circuitry indication of a fully charged Smartphone  10  internal battery. 
     Referring to  FIGS. 4 and 5  a second visual indicator, LED indicator  90  is shown. The purpose of this visual indicator may be to indicate that power is supplied to the Smartphone Charging Alarm Feedback Device  40  through USB Type A Male  130  cable which may be accessible from the exterior housing of the Smartphone Charging Alarm Feedback Device  40 . The color of said LED may be selected and/or changed as defined by the inventor. Power supply to the Smartphone Charging Alarm Feedback Device  40  may be achieved by plugging the USB Type A Male  130  cable attached to the Smartphone Charging Alarm Feedback Device  40  into a Smartphone charging device  30  as shown in  FIG. 3 . It should be noted that the Smartphone charging device  30  may be plugged into an AC voltage receptacle. It should also be noted that a Smartphone  10  does may not have to be connected to the Smartphone Charging Alarm Feedback Device  40  as previously described in order for LED indicator  90  to function when the Smartphone Charging Alarm Feedback Device  40  is connected to a Smartphone charging device  30 . 
     It should be noted that a standard USB Type A Male to USB Type B Male cable  20  may include two digital signal lines that may be used for data transfer to and from the Smartphone  10  and/or other functions. Referring to  FIGS. 4 and 5 , the Smartphone Charging Alarm Feedback Device  40  may not utilize the two digital signal lines previously described. Rather they may be passed through the Smartphone Charging Alarm Feedback Device  40  in an uninterrupted state via the USB Type A Male  130  cable. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.