Abstract:
A self-contained power supply module operating from utility power and having short term energy storage in the form of a battery or capacitor is adapted for powering electronic consumer devices especially during brief brownout and power outages of the utility. The self-contained power supply module is a low cost power supply having an integral AC plug adapted for connection in a standard electrical wall outlet. The integral battery or capacitor provides continuous and clean power to electronic consumer devices that may lose programmed information stored therein due to brief power interruptions thereto.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to power modules for consumer electronic devices, and, more particularly, to a power module that is separate from the consumer electronic device and is adapted to plug into an electric power outlet and to supply a desired voltage to the consumer electronic device even during power utility brownouts and short duration power outages. 
     DESCRIPTION OF THE RELATED TECHNOLOGY 
     Consumer electronic devices shall be defined herein as electronic products or devices that may be used at home or in an office. These consumer electronic devices may be for example, but not limited to, telephones having memory storage, programmable digital alarm clocks, digital electronic address and information appliances, telephone answering machines, video game play stations, cable and satellite television interface boxes, smart modems, digital subscriber line (DSL) modems and routers, ethernet network hubs and switches, sprinkler system control panels, security card readers, security access keypad panels, programmable thermostats, garage door opener controllers, programmable door bell annunciators, etc. 
     Generic power supply modules typically power these consumer electronic devices and may be provided as a power supply interface between an electrical power outlet and the consumer electronic device. The generic power supply module may be either a linear or switching power supply that receives utility service line voltage and produces a lower voltage compatible with the consumer product being powered thereby. This lower voltage may be either alternating current (AC) or direct current (DC). The power supply module is typically adapted to plug into an electric wall outlet, either with a short power cord and plug cap or directly into the face of the electric outlet. 
     Generally, consumer electronic devices must be low cost and without unnecessary parts so as to stay competitive with other competing products. As such, non-volatile memory or expensive memory back-up systems are not included in order to maintain the cost competitiveness of these devices. Thus, the design of these devices assumes that utility power will be continuous. This, however, is not always the case and when there is a minor power dip (brownout) or short duration loss of power these devices typically loose information stored in volatile memory (lower in cost than non-volatile memory) such as registers and latches, static random access memory (SRAM), dynamic random access memory (DRAM) and the like. This information may be frequently dialed telephone numbers, time and alarm settings, time of day and date, network and router settings, local and cable television channels, television program schedules, billing information and user identity, temperature-time profiles, recorded messages, etc. 
     Small uninterruptible power supplies (UPS) have been used to protect larger and more expensive computer systems during a power brownout or unexpected power interruptions, but the computer components to be backed up must be within a power cord distance from the UPS. Typical UPS systems are disclosed in U.S. Pat. Nos. 5,751,564; 5,834,858; 5,811,895; and 5,920,129. The consumer electronic devices, however, are generally spread throughout the home or office, along with their respective power supply modules, thus making use of a common UPS for power backup purposes impractical. 
     What is needed is an inexpensive and effective way of preventing loss of information stored in volatile memory of a consumer electronic device during power brownout or short duration power interruptions. 
     SUMMARY OF THE INVENTION 
     The invention overcomes the above-identified problems as well as other shortcomings and deficiencies of existing technologies by providing an integrated power supply module comprising a power converter in combination with an energy storage device for powering a consumer electronic device and, in addition, preventing loss of information stored in volatile memory of the consumer electronic device during power brownout or short duration power interruptions. The power supply module, sometimes referred to as a “wall-wart,” is adapted to plug into an electric wall outlet, either with a short power cord and plug cap or directly into the face of the electric outlet, and connect to the consumer electronic device. The power supply module converts the voltage at the wall outlet to a voltage compatible with the consumer electronic device. The power supply module may produce either alternating current (AC) or direct current (DC), depending on the requirements of the consumer electronic device. The storage device may be a battery, a rechargeable battery or a capacitor adapted so as to provide power through the power supply module to the consumer electronic device during a power utility brownout or short duration loss of power. In addition, it is contemplated and within the scope of the invention that transient voltage protection may also be incorporated in combination with the power supply module and energy storage device. 
     In an embodiment of the invention the power module is encased in some form of insulated enclosure in compliance with UL (R)  and/or CSA standards. The enclosure may have a two pin male connector which is integral therewith, or a power cord and plug cap (two pin male connector). The male connector is adapted to mate with contacts in the wall receptacle so as to make electrical connection thereto and also derive mechanical support therefrom. A three pin male connector which is integral therewith, and a power cord and plug cap (three pin male connector) having a safety ground connection are also contemplated herein. The three pin male connector embodiment of the invention may also be encased in a metal enclosure attached to the grounding pin of the three pin male connector. 
     The energy storage device is integral with the power module enclosure. The energy storage device may be located on the inside or outside of the enclosure, and may be fixed in or on, and/or removable from the enclosure. When the energy storage device is a rechargeable battery, circuits of the power converter in the power supply module may be used to recharge this rechargeable battery when utility power is present so as to maintain a full charge therein. 
     The power supply module may be adapted for a removable rechargeable or non-rechargeable battery or batteries and may have an appropriate battery holder or compartment that may physically retain the battery or batteries and have an electrical connector or contacts integral or associated therewith that is adapted for making electrical connection to the battery or batteries. 
     A battery charge or condition indicator may be included with the power supply module and may be, for example, but not limited to, a light for indicating charge state or discharge state when a non-rechargeable battery is used. A tone or pulsed tone (beep) may also be used instead of or in addition to the indicator light, for signaling a low battery charge condition. Any signaling device may be used to indicate the need to replace a non-rechargeable battery. 
     Battery condition status may also be transmitted to the consumer electronic device by, for example, but not limited to, an infrared transmitter, carrier current signal on the power supply wiring, a USB port, etc. 
     The present invention may be utilized with existing consumer electronic devices as a replacement component for an existing power supply module so as to prevent or reduce brownout and/or loss of power related mis-operation and/or failures of the consumer electronic device. Many different types and models of consumer electronic devices may be powered by the present invention, thereby improving economics of scale and reducing manufacturing costs thereof. 
     An advantage of the present invention is compatibility with existing and future consumer electronic devices. 
     Another advantage is simplification of the design and reduction of the cost of consumer electronic devices. 
     Still another advantage is improved operation and reduced malfunctions of consumer electronic devices. 
     Another advantage is low cost through mass production for use with a plurality of different consumer electronic devices. 
     A feature of the present invention is an energy storage device for preventing brownout and short duration loss of power in a consumer electronic device. 
     Another feature is a removable battery. 
     Still another feature is a low battery charge indicator. 
     Yet another feature is a rechargeable battery that is automatically charged by the power converter in the power supply module when the connected utility power is operational. 
     Other and further advantages and features will be apparent from the following description of presently preferred embodiments of the invention, given for the purpose of disclosure and taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic diagram of a consumer electronic device powered by a power supply module having a removable battery, according to an embodiment of the invention; 
     FIGS. 2A and 2C are schematic side views of embodiments of the power supply module of FIG. 1; 
     FIGS. 2B and 2D are schematic rear views of embodiments of the power supply module of FIGS. 2A and 2C, respectively; 
     FIGS. 2E and 2F are schematic side views of other embodiments of the invention; 
     FIG. 3 is a schematic block perspective diagram of another embodiment of the invention having an internal battery; 
     FIG. 4 is a schematic front view illustrating battery status indication; 
     FIG. 5 is a schematic functional block diagram of an embodiment of the invention; and 
     FIG. 6 is a schematic functional block diagram of another embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The invention is a power supply module comprising a power converter and an energy storage device. The power supply module is used to power a consumer electronic device and to prevent loss of information stored in volatile memory of the consumer electronic device during power brownout or short duration power interruptions. Voltage transient protection may be incorporated into the power supply module. Indication of battery status or condition may also be incorporated into the power supply module, according to an embodiment of the present invention. The present invention may have an input that operates over a wide range of utility utilization voltages, typically from about 100 volts to about 250 volts, preferably from about 110 volts to about 125 volts, and most preferably about 117 volts. Other utility utilization voltages may be used with the present invention and are contemplated herein. An output voltage for the consumer electronic device may be supplied from about 5 volts to 48 volts, preferably from about 8 volts to about 24 volts, and most preferably from about 9 volts to about 15 volts. 
     Referring now to the drawings, the details of preferred embodiments of the invention are schematically illustrated. Like elements in the drawings will be represented by like numbers, and similar elements will be represented by like numbers with a different lower case letter suffix. 
     Referring to FIG. 1, a schematic diagram of a consumer electronic device powered by a power supply module having a removable battery is illustrated. The power supply module of FIG. 1 is generally represented by the numeral  100 . The power supply module  100  comprises a power converter  102  and a removable battery  104 . The power supply module  100  is adapted to be plugged into a wall power receptacle  108  and connected to a consumer electronic device  110 . The power supply module  100  supplies operating power to the consumer electronic device  110 . The removable battery  104  may be any of the commonly used consumer type batteries such as, for example, but not limited to, one or more A or AA batteries in a battery holder, a 9 volt battery having snap connections thereon, etc. The removable battery  104  may be non-rechargeable carbon, alkaline or the like, or the battery may be rechargeable nickel cadmium, lead acid, and the like. 
     Referring to FIGS. 2A and 2B, schematic side and rear views of a power supply module are illustrated, according to an embodiment of the present invention. The power supply module  100   a  comprises a housing  202   a,  male plug contacts  204  and a power cable  106  adapted to connect to the consumer electronic device  110 . Generally, the power cable  106  has a plug connector that mates with a corresponding socket in the consumer electronic device  110 . The housing  202   a  is generally made of an insulating material which meets the requirements of UL and CSA as being a “double insulated enclosure” not requiring grounding. The male plug contacts  204  are further identified in FIG. 2B as contacts  204   a  and  204   b,  representing “ungrounded” and “neutral” plug contacts adapted for the corresponding contacts of the wall outlet socket  108  (FIG.  1 ). An internal energy storage device  304  (FIG.  3 ), such as a rechargeable battery or capacitor may be contained in the housing  202   a  in combination with the power converter  102  (FIG.  1 ). 
     Referring to FIGS. 2C and 2D, schematic side and rear views of a power supply module are illustrated, according to another embodiment of the present invention. The power supply module  100   b  comprises a housing  202   b  and male plug contacts  204  and  206 . The housing  202   b  is generally made of either an insulating or conductive material. To meet the requirements of UL and CSA, the power supply module  100   b  must be grounded through the contact  206  which is adapted for connection to the grounding contact of the wall outlet socket  108  (FIG.  1 ). The male plug contacts  204  are further identified in FIG. 2D as contacts  204   a  and  204   b,  representing “ungrounded” and “neutral” plug contacts adapted for the corresponding contacts of the wall outlet socket  108 . A battery holder  208  is provided on the exterior surface of the housing  202   b  for removably holding the battery  104 . 
     Referring to FIG. 2E, a schematic side view of a power supply module is illustrated, according to yet another embodiment of the present invention. The power supply module  100   c  comprises a housing  202   c,  a two wire power cord  210   a  having a male plug cap  212   a  adapted to plug into the wall outlet socket  108  (FIG.  1 ), and a power cable  106  adapted to connect to the consumer electronic device  110  (FIG.  1 ). The male plug cap  212   a  has contacts  216  and  218 , representing “ungrounded” and “neutral” plug contacts, respectively, adapted for the corresponding contacts of the wall outlet socket  108 . Generally, the power cable  106  has a plug connector that mates with a corresponding socket in the consumer electronic device  110 . The housing  202   c  is generally made of an insulating material which meets the requirements of UL and CSA as being a “double insulated enclosure” not requiring grounding. An internal energy storage device  304  (FIG.  3 ), such as a rechargeable battery or capacitor may be contained in the housing  202   c  in combination with the power converter  102  (FIG.  1 ). 
     Referring to FIG. 2F, a schematic side view of a power supply module is illustrated, according to still another embodiment of the present invention. The power supply module  100   d  comprises a housing  202   d,  a three wire power cord  210   b  having a male plug cap  212   b  adapted to plug into the wall outlet socket  108 , and a power cable  106  adapted to connect to the consumer electronic device  110 . The housing  202   d  is generally made of either an insulating or conductive material. To meet the requirements of UL and CSA, the power supply module  100   d  must be grounded through the plug cap  212   b  contact  214  which is adapted for connection to the grounding contact of the wall outlet socket  108  (FIG.  1 ). The male plug cap  212   b  also has contacts  216  and  218 , representing “ungrounded” and “neutral” plug contacts, respectively, adapted for the corresponding contacts of the wall outlet socket  108 . A battery holder  208  may be provided on the exterior surface of the housing  202   d  for removably holding the battery  104 . 
     Referring now to FIG. 3, another embodiment of the invention having an internal energy storage device is illustrated. The power supply module  100  comprises a housing  302  enclosing the power converter  102  and an internal energy storage device  304 . The internal energy storage device  304  may be a rechargeable battery or a capacitor. The rechargeable battery may be any type know to one of ordinary skill in the art of batteries. The capacitor is of sufficient energy storage capacity to sustain the consumer electronic device through a short duration brownout or loss of utility power. The power converter  102  is adapted to charge the rechargeable battery (energy storage device  304 ) when the utility power is functional, and is further adapted to be powered from the rechargeable battery when there is a utility brownout or power failure. 
     Referring to FIG. 4, a schematic front view of battery status indication is illustrated. The power supply module  100  may have a battery status indicator, for example, but not limited to, a light  414  and/or an audible alarm  412 . The battery status indicator may represent a low charge condition for the battery  104  (FIG. 1) which may indicate that a non-rechargeable battery requires replacement, or that a rechargeable battery requires recharging. The light  414  may light-up, flash on and off, change color, etc., and the audible alarm may beep, warble, have a steady tone, etc. 
     It is contemplated and within the scope of the present invention that digital signaling may also be incorporated to indicate the status of the power converter  102  and/or the energy storage device  304 . A carrier current signal on the power cable  106  to the consumer electronic device  110 , an additional signal wire(s) in the power cable  106 , a digital port  416  such as universal serial bus (USB) may be adapted to connect to the consumer electronic device  110 . Any of type of signal circuit known to one of ordinary skill in the art may be used to alert the consumer electronic device  110  that there has been a utility power brownout or power failure. Once alerted by the signal circuit (not illustrated), the consumer electronic device  110  may take evasive action (save critical data, go offline, etc.) in the event that the power failure time duration may exceed the capabilities of the power supply module  100  to maintain proper operating voltage therefor. 
     Referring to FIG. 5, a schematic functional block diagram of an embodiment of the invention is illustrated. The power supply module  100  comprises a voltage converter  502 , a battery  104 , a battery charger  504  (when a rechargeable battery is used), a battery condition monitor  506 , a low battery annunciator  412  and/or a low battery indicator  414 . In normal operation, the voltage converter  502  receives power from the utility (power receptacle  108  of FIG. 1) and converts the utility voltage at, for example, 60 Hertz alternating current (AC) into a desired voltage and either an AC or direct current (DC) to operate the consumer electronic device  110 . The consumer electronic device  110  functions correctly so long as there is voltage being supplied thereto. The battery condition monitor  506  monitors the charge state of the battery  104  and may be adapted for controlling the low battery annunciator  412  and/or low battery indicator  414  depending upon the charge condition of the battery  104 . 
     The power supply module  100  normally supplies power to the consumer electronic device  110  from the power receptacle  108 , but when there is a voltage brownout or short term voltage loss then power is obtained from the battery  104  and converted by the voltage converter  502  to the desired voltage and current values required by the consumer electronic device  110 . Depending upon the energy storage capacity of the battery  104 , the consumer electronic device  110  will correctly operate for a desired time without the utility power being present at the power receptacle  108 . The voltage converter  502  is designed to transfer its source of power from the power receptacle  108  to the battery  104 . Any circuit known to one of ordinary skill in the design of battery backup power supplies may be adapted for the voltage converter  502 . A typical circuit is disclosed in U.S. Pat. No. 5,811,895, entitled “Power Supply Circuit for Use with a Battery and an AC Power Adaptor” by Suzuki et al., and is hereby incorporated by reference. 
     Referring to FIG. 6, a schematic functional block diagram of another embodiment of the invention is illustrated. The power supply module  100  comprises a voltage converter  602  and an energy storage capacitor  604 . In normal operation, the voltage converter  602  receives power from the utility (power receptacle  108  of FIG. 1) and converts the utility voltage at, for example, 60 Hertz alternating current (AC) into a desired voltage and either an AC or direct current (DC) to operate the consumer electronic device  110 . The consumer electronic device  110  functions correctly so long as there is voltage being supplied thereto. 
     The power supply module  100  normally supplies power to the consumer electronic device  110  from the power receptacle  108 , but when there is a voltage brownout or short term voltage loss then power is obtained from the energy storage capacitor  604  and converted by the voltage converter  602  to the desired voltage and current values required by the consumer electronic device  110 . Depending upon the energy storage capacity of the energy storage capacitor  604 , the consumer electronic device  110  will correctly operate for a desired time without the utility power being present at the power receptacle  108 . The voltage converter  602  is designed to draw power from the energy storage capacitor  604  during the brief periods of time of a brownout or short duration voltage dip at the power receptacle  108 . The circuit of the voltage converter  602  may be an AC to DC converter, which charges the energy storage capacitor  604  with a DC voltage and which may reconvert the DC voltage back to a desired AC voltage for the consumer electronic device  110 . If the consumer electronic device  110  operates from a DC voltage, the voltage converter  602  need only produce this DC voltage which simultaneously charges the energy storage capacitor  604  and powers the consumer electronic device  110 . 
     It is contemplated and within the scope of the present invention that transient voltage and/or surge current protection may be incorporated with any or all of the aforementioned embodiments. This aspect of the invention further improves the robustness of the power supply module  100  to abnormal operating conditions. 
     The invention, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While the invention has been depicted and described and is defined by reference to particular preferred embodiments of the invention, such references do not imply a limitation on the invention, and no such limitation is to be inferred. The invention is capable of considerable modification, alternation and equivalents in form and function, as will occur to those ordinarily skilled in the pertinent arts. The depicted and described preferred embodiments of the invention are exemplary only and are not exhaustive of the scope of the invention. Consequently, the invention is intended to be limited only by the spirit and scope of the appended claims, giving full cognizance to equivalents in all respects.