The invention relates to power supplies and, in particular embodiments, to parallel power supplies for low voltage devices such as ornaments.
Electrically powered display devices are often used in displays for holidays, celebrations, special occasions and entertainment. Some displays powered by electricity may be used in storefronts and other commercial displays to attract attention or to provide amusement. Such display devices may include visual elements, such as light displays of various kinds. Other display devices may provide audio elements, such as music, singing, synthesized voices, or natural sounds. Other displays may involve motion or rotation of objects. Some displays include combinations of audio and visual elements in an integrated display to provide the observer with an enhanced experience.
When operating electrical devices, current and voltage levels must be supplied at levels appropriate to the electrical load of each device. Some devices, for example, require an alternating current (AC) power source, while others may require a direct current (DC) power source. Some electrical loads may accept only a narrow range of input voltages, while other devices may be operated over a wider range of voltages. For example, some types of light devices may be “dimmed” to provide various levels of illumination. As such, each electrically powered device in a display must be supplied by an appropriate power source.
Displays that require multiple power sources to supply electrical power to multiple devices typically require a separate source of AC or DC power for each device. In some cases, this may typically involve a number of extension cords, wall outlets, or sets of batteries. To reduce the danger of electrical shock and the risk of fire from an over-current condition, each separate power source may provide protection against circuit faults.
A load management controller (LMC) can include a power distribution circuit to supply and regulate current to a plurality of low voltage devices. In certain embodiments, the LMC may receive power from an AC power source and may further include an AC-AC transformer, a microcontroller to regulate voltage and current to user programmable levels, one or supplementary current limiters, and a plurality of receptacles to removably and electrically couple the LMC to the plurality of low voltage devices. In various embodiments, the low voltage devices comprise lights, motors, actuators, and/or audio devices.
In certain embodiments, the LMC may provide output power in other forms, such as variable AC (dimmer), intermittent AC, DC, and variable DC. The LMC may optionally include circuit protection devices and equipment. For example, circuit breakers, fuses, and positive temperature coefficient resistors may provide circuit protection. Circuit protection may include a main protection element, as well as branch protection elements for one or more output branches.
In still another embodiment, the LMC microcontroller may monitor faults and execute instructions to operate one or more display elements. The LMC may, in some examples, be configured to accept user programming to specify the operation of display elements in a desired manner.
Some embodiments may provide one or more of the following advantages. High current output capacity may provide sourcing capacity for a number of loads. This may reduce the number of power sources required for a display, and may enable displays in areas lacking multiple outlets. Moreover, high current capacity may improve brightness levels of displays and enhance an observer's viewing experience. Over-current protection may be provided for multiple loads and may also be provided for individual loads. A low voltage level may reduce the risk of electrical shock hazard potential. Portability may reduce the number and length of power cords in a display, resulting in an uncluttered appearance.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.
Like reference symbols in the various drawings indicate like elements.
The load management controller (LMC) 108 may be used to provide relatively low-voltage and high-current AC output signals for powering AC loads. As such, a user's risk of electrical shock may be reduced because of the relatively low voltage of the output AC signal, thus providing a safer environment for displaying AC-powered ornaments and other types of AC loads. Moreover, because a relatively high current capacity is provided, a large number of loads may be powered by the load management system 100, facilitating the creation of complex displays having a diverse variety of ornaments, for example. Furthermore, brightless levels of lighted ornaments may be improved, enhancing the appearance of the display.
The AC signal from power supply 104 enters the LMC 108 at an input port 112, to which connector 114 may attach. Connector 114 includes a plug 116 that may be inserted into input port 112. Plug 116 is electrically connected to cable 110, and may include two conductors that are suitable for conducting the AC signal from the power supply 104 to the LMC 108. In one embodiment, LMC input port 112 is a receptacle for a female plug and plug 116 is a female plug, but port 112 could be receptacle for a male plug and plug 116 could be a male plug, and those skilled in the art will recognize that other electrical connecting mechanisms are possible. Plug 116 may be partially enclosed in a flexible elastomer 118 to provide stress relief, strength, support and insulated protection for the connector 114.
LMC 108 may provide a plurality of output ports 120, to which output connectors 122 may attach.
Output connector 122a is coupled to a proximal end of an interconnect cable 124, and a similar connector 126 is coupled to a distal end of the interconnect cable 124. Connector 126 includes a plug 128 that may be inserted into a receptacle 130 of an ornament 132 to provide AC power to the ornament 132. The ornament 132 in
LMC 108 additionally includes an indicator light 136 that may indicate when input power is applied to the LMC 108. For example, indicator light 136 may be a green light-emitting diode (LED) that turns on when connector 114 supplies an input AC signal to LMC 108 at input port-112. In other embodiments, additional indicator lights 136 of various colors and shapes may be used to indicate fault conditions, warning notifications or other user information. In some embodiments, a speaker may additionally provide tones or warning messages to simultaneously or independently alert a user to such conditions.
A button 138 may allow a user to reset a current-limiting element, such as a fuse or a circuit breaker. Non-resettable current-limiting devices, such as a positive temperature coefficient (PTC) resistor, may also be used. The current limiting element protects the LMC 108 from over-current situations such as a short on one or more of the outputs or a low impedance fault, each of which could otherwise be harmful to the various components of the load management system 100. The user might be alerted to the need to reset the current limiting element, for example, by an LED indicator on the LMC 108, and may then press button 138 to execute the reset.
LMC 108 may be suspended from a support member by an attached loop hanger 140. For example, LMC 108 may be hung from a branch of a Christmas tree, which may place LMC 108 in close proximity to ornaments 132 also hanging from the tree, thereby minimizing the required length of interconnect cables 124. Moreover, loop hanger 140 may permit LMC 108 to be hung from a support member such that it is hidden from view, if so desired, thus permitting display viewers to focus on the display without distraction. Of course, LMC 108 need not be suspended using loop hanger 140, and other types of hanging devices may be used, such as a hook, a clamp or the like.
Connections 214 in
Resettable current limiting element 304 is connected at node A to a pair of light-emitting diodes 306. The diodes are in a bidirectional arrangement, with the cathode of diode 306a connected to the anode of diode 306b and to current limiting element 304 at node A. The anode of diode 306a is then connected to the cathode of diode 306b, and also to a current limiting resistor 308. The current limiting resistor is connected at node B to the common contact 302 of input port 112, and may be selected to draw an appropriate current through diodes 306. In one embodiment, resistor 308 may be sized at 220 ohms and diode 306b corresponds to indicator light 136 in
The output ports 120 are shown at the right side of the LMC 108. In the embodiment shown in
Output fuses 314a-314j are optional, as is resettable current limiting device 304. The output fuses 314 could similarly be resettable by a user, for example by pushing a button on the LMC 108, and could be replaced by circuit breakers or PTC resistors. In one embodiment, output fuses 314 may be sized at 0.5 amps to ensure that output current to an AC load never exceeds 0.5 amps, thereby protecting the loads from over-current damage. Both the input port 112 and output ports 120 may have staggered contact points so that a user who might accidentally touch an outermost edge of the port will be protected from electrical shock because the second contact point is set back in the port 112, 120. This may prevent injury to a user and provide a safer environment for attaching connectors 114, 122 to the LMC 108. Moreover, because the ports 112, 120 may be gender-specific receptacles, a user who attempts to incorrectly attach a connector 114, 122 to the LMC 108 will be alerted to the error when the receptacle fails to engage the connector, and the mistake can be corrected.
Over-current situations can be accordingly avoided by providing primary and/or secondary fuses, circuit breakers, or other current limiting devices. IC (integrated circuit) current limiters together with any necessary rectifiers and inverters (depending on whether inputs and outputs are AC or DC) could be coupled between the input and output terminals. Multiple IC current limiters could additionally or alternately be used in place of elements 314a-314j. Another approach to limit current is to equip the output connectors 122 with insulative plugs adapted to seal one or more adjacent output plugs. Accordingly, devices which draw relatively large amounts of current can be equipped with such plugs so as to reduce the number of devices that can be plugged into LMC 108 and thereby prevent an over-current situation.
A string of lights 400 includes bidirectional light pairs 402 connected in parallel and attached to output port 120a. The lights 400 may be a string of decorative holiday lights, for example, and may be powered by an AC signal provided by output port 120a. Similarly, strings of lights 400 are attached to output ports 120e, 120g and 120h. Each of the light strings 400 may contain lights 402 of the same color, or alternatively the lights 402 may be different colors as desired. Series-connected loads may also be powered.
A rectifier 404 is attached to output port 120b and converts an input AC signal to an output direct current (DC) signal suitable for powering a DC load, such as a DC motor 406. The rectifier may optionally be positioned inside the LMC 108. In the depicted embodiment, the DC output ports may provide an alternative power source for some battery-operated devices. The DC motor might be used to provide motion to displays and exhibits, enabling the creation of more complex and interesting displays. For example, perhaps one item in a planetary display consists of a model of Jupiter mounted above a base on an axis that runs through the model planet. The DC motor 406 may be concealed under the base and used to rotate the axis, causing the model of Jupiter to spin on the axis. Similarly a rectifier/motor combination 404/406 attached to output port 120f may be used to rotate a model of Saturn, or one or more of Jupiter's moons in the planetary display. The light strings 400 might be used to represent distant star constellations in the display, for example. Additional rectifier/motor loads may be added to correspond to the other planets in the solar system, for example.
A timer 408 is attached to output port 120c and also to a local AC device 410. Similarly to the rectifier, the timer may be positioned within LMC 108. The timer 408 facilitates intermittent loads and includes a switch 412 for making or breaking a connection between the output port 120c and the AC device 410, and a dial 414 to permit a user to control the operation of the switch 412. In this example, AC device 410 may be an ornament representing the title of the display and may blink on and off according to a user-defined pattern programmed into timer 408 using dial 414. A speaker 416 is attached to output port 120d and may add sound to the exhibit, for example by playing music. As such, complex displays having various types of ornaments, exhibits and effects are possible using load management system 100.
A microcontroller 606 may execute software instructions to perform algorithms and tasks associated with managing the various functions of the LMC 600. As is conventional, the software instructions may initially be stored in non-volatile memory 608 such as read-only memory (ROM), flash memory, electronically programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM) and the like. Non-volatile memory 608 may be updatable, such that software updates may be provided or downloaded to the LMC 600, for example by using a JTAG interface, a dedicated reprogram header and cable, or by replacing a socketable chip. Reprogramming the LMC may be accomplished, for example, by wired or wireless communication over the Internet or a Bluetooth connection with provision of suitable transceivers and controllers. LMC 600 may be reprogrammed using a personal computer, personal digital assistant (PDA), cell phone, or any other appropriate device. LMC 600 may include a telemetry module (not shown) to facilitate wireless communication with external devices.
As is conventional, the software instructions may be loaded from non-volatile memory 608 to a local memory 610, from which microcontroller 606 may access the instructions and execute them. Memory 610 may be static random access memory (RAM), non-volatile random access memory (NVRAM), dynamic RAM (DRAM) or the like. Of course, memories 608 and 610 may be incorporated within the microcontroller, or may be combined in a single device. A display 612 allows text or display messages to be presented to a user. In one embodiment, display 612 includes a liquid crystal display (LCD) and associated drive circuitry. Display 612 may be backlit to provide ease of readability in low lighting conditions and may include sleep modes that dim or turn off the display 612 during periods of non-use.
Similarly, LMC 600 may include a group of status indicator lights 614, represented in
A group of selection inputs 620 permit a user to select between various modes of operation or otherwise specify input parameters relevant to the operation of the LMC 600. Inputs 620 may include toggle switches, jumpers, buttons, and multi-position switches such as slide switches. An input selection interface module 622 includes filtering and protection circuitry for the selection inputs 620, and passes the inputs to the microcontroller 606. For example, a user may activate inputs 620 to enable or disable a group of output ports 120, or to select an activation sequence among the output ports 120. Some inputs 620 may further clear or reset fault or warning conditions. Used independently or in conjunction with display 612, inputs 620 may further be used to program LMC 600 to execute various display management operations. For example, LMC 600 may be programmed to manage three distinct displays patterns for a given set of output loads. One pattern might be displayed in the morning, another in the afternoon, and a third in the evening, with a user specifying the correct pattern using inputs 620. Alternatively, microcontroller 606 may include a real-time clock and automatically switch between display patterns as appropriate.
A DC module 626 includes a rectifier circuit and various voltage regulators to provide DC output voltages at corresponding output ports 120 to power DC loads, which may previously have required battery power. For example, DC module 626 may source output ports 120 at 12V, 9V, 6V, 5V, 4.5V, 3V and 1.5V. This may provide a more convenient and environmentally friendly power solution than replaceable batteries, as well as potentially minimizing both downtime and maintenance time.
An amplifier circuit 628 drives a speaker 630, which may be incorporated within LMC 600 or external. Selection inputs 620 may be used to set the volume, bass or treble levels of the speaker 628, for example. An AC load interface module 632 controls a group of AC output ports 120, and may provide power for light, sound, or motion display elements.
The components shown in
A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, LMC input ports 112 and output ports 120 could be located on any side of the LMC 108, and the number of each type of port 112, 120 may be varied. For example, LMC 108 may have two input ports 112, and may have eight, ten, twelve, sixteen, twenty, or any other number of output ports 120. Similarly, indicator lights 136 and buttons 138 may be located on any side of LMC 108 and various numerical combinations of each are possible. Accordingly, other embodiments are within the scope of the following claims.