Patent Application
20090206665
1. Technical Field of the Invention
The present invention relates, generally, to an apparatus for controlling a distribution of electrical power to subsystems, e.g., to a primary device and at least one secondary device.
More particularly, the present invention relates to an apparatus for controlling a distribution of power formed as an electrical power strip and power control sensors, which can be used with new devices having a plurality of modes of operation, e.g., standby or “off” and full “on,” with the use of a primary device or secondary devices.
2. Description of the Prior Art
One type of an electrical distribution device known to the art is the power strip or power control center, which generally comprises of a row of power outlets, that can be either switched or unswitched, for distributing power to a primary device and one or more secondary devices from a standard outlet (e.g., wall outlet). Some of these known power strips and control centers contain various options, such as, circuit breakers, fuses and/or surge protectors.
In many newer personal computer systems, the system can shut itself “off” upon command from the operating system. During system shutdown, there is a delay during which the operator must wait for the personal computer system to complete its shutdown before proceeding to separately turn off secondary devices, such as printers and monitors. Depending upon the operating software and application programs, this waiting period can be significant. The present invention, as detailed hereinafter, proceeds to turn off the secondary, or peripheral, devices after a user directs the operating system of the computer system to commence shutdown of the computer; the user not being required to await shutdown of the computer before proceeding to separately turn off the secondary devices.
Known to the prior art are various devices and methods for controlling the operation of secondary devices, as broadly disclosed in U.S. Pat. No. 4,731,549; U.S. Pat. No. 4,825,140; and U.S. Pat. No. 4,970,623. The apparatuses and methods taught by the foregoing prior art patents all require internal power supplies and numerous components, rendering each too expensive for mass production and difficult to connect to in a standard power strip. Such devices also use standby power, inasmuch as an internal power supply is always on.
Various improvements over the devices disclosed and suggested by the foregoing references are disclosed in the inventors' U.S. Pat. No. 6,501,195; U.S. Pat. No. 6,528,902; U.S. Pat. No. 6,759,762; U.S. Pat. No. 6,759,763; and P.C.T. Application Publication No. WO 2006/022632.
It is, therefore, an object of the present invention to provide an apparatus for controlling the distribution of electrical power to secondary subsystems, for example, computer peripheral devices, that allows, e.g., for an automated shutdown or switch to a “standby” mode of the secondary subsystems, once a shutdown of the primary system has been undertaken.
It is a further object of the present invention to provide an apparatus for controlling the distribution of electrical power to secondary subsystems that overcomes the inherent drawbacks of the prior art.
The foregoing and related objects are accomplished by the present invention, which provides an apparatus for controlling a power distribution to subsystems that includes a power input that is to be connected to a power source and a primary power output to be connected to a primary device, along with at least one secondary power output, which is to be connected to at least one secondary device. Means for sensing is included for sensing when a current level falls below a first predetermined threshold, in response to the primary device being turned off, deactivated or “on standby,” as well as for sensing when the current level rises above a second predetermined threshold in response to the primary device being turned “on” or activated. Executing means is connected with the sensing means and operative for interrupting a power supply to, at least, one second-ary device when the sensing means senses that the current level has fallen below the threshold; the executing means is able to supply power to one or more secondary devices when the sensing means senses that the current level is above the threshold.
Low current operating means is included for increasing the voltage required for triggering the executing means, despite there being a relatively small output of the sensing means, with the lower current operating means being capable of increasing the voltage of the executing means without negatively affecting the sensing means. The low current operating means, in a preferred embodiment, uses a voltage reference for preventing a triggering level change with source voltage changes.
Also in accordance with the present invention, a low current operating voltage increasing means includes a voltage divider or voltage reference means.
In accordance with a further embodiment of the present invention, the sensing means can be formed as a current sensing coil or transformer arranged to the input of the triggering device and, at one side, connected to the voltage increasing means.
The executing means can, for example, be formed as a DC relay, an AC relay or as a solid state AC relay. Alternative relay devices operative with the present invention can be readily determined by those skilled in the art.
When the present invention is used in connection with a computer system, each secondary device is plugged into a separate outlet with the primary computer device being plugged into a primary outlet. When the computer is turned on, the current level would increase to a sufficient level to turn on the secondary device(s). Other constant power outlets may also be included for wake-up devices, such as modems capable of bringing the system out of “standby” mode.
Other objects and features of the present invention will become apparent when considered in combination with the accompanying drawing figures which illustrate certain preferred embodiments of the present invention. It should, however, be noted that the accompanying drawing figures are intended to illustrate only certain embodiments of the claimed invention and are not intended as a means for defining the limits and scope of the invention.
In the drawing, wherein similar reference numerals and symbols denote similar features throughout the several views:
An apparatus for distributing power to subsystems in accordance with a first embodiment of the present invention, as shown in
A voltage divider is formed by two resistors (R2 and R3), so that a small voltage is formed across the bias resistor (R2). This voltage is sufficiently small so as not to trigger the gate of the SCR (Q1). The resistors (R2 and R3) form means for increasing the voltage to provide triggering of the executing means despite the small output of the current sensing coil (L1-T1).
The bias resistor (R2) and the capacitor (C1) form a time constant to filter out line noise and prevent false triggering of the SCR (Q1).
When the voltage across the current sensing coil, created by the main device power level, plus the voltage across the bias resistor (R2), exceeds the gate trigger voltage of the SCR (Q1), the SCR (Q1) will switch on. Current then flows through the SCR (Q1), current limiting resistor (R5), to charge the capacitor (C2). The current limiting resistor (R5) limits the current to the SCR (Q1), as well as forming a resistive capacitive time constant to slow down the charging the capacitor (C2). This helps prevent false triggers, as well as creating a turn on time delay for one or more secondary systems, if desired.
The energy now stored in capacitor (C2) turns on a relay (RLY1) to control power supply to secondary power outputs (SPO), to which one or more of the secondary system devices are connected.
A hysteresis resistor (R4) is used to lower the voltage across the bias resistor (R2) when the relay (RLY1) is off. When the relay is on, one side of the hysteresis resistor (R4) is disconnected, increasing the voltage across the bias resistor (R2). This prevents oscillation of the relay (RLY1) if the main device power level is close to the threshold of the sensing means.
A diode (D1) is used to lower the power used by the voltage divider resistors (R2 and R3), but is not required.
In the foregoing embodiment, the current sensing coil or transformer (L1-T1), together with the bias resistor (R2) and the SCR (Q1), constitute sensing means which sense a current level that is either below, or above, a predetermined threshold. The relay constitutes executing means which, in response to the sensing of the current level by the sensing means, interrupts the current supply to the secondary device(s), when the sensed level is below the threshold as a result of turning off the primary device, or supplies the current to the secondary device(s), when the current level sensed by the sensing means is above the threshold, as a result of turning on the primary device.
It is to be understood that the apparatus in accordance with the present invention can be used on many different voltages by changing the resistor values, including, but not limited to, 100-, 120- and 220-VAC, for domestic and foreign use.
Alternatively, instead of the SCR (Q1) transistors, other switching devices may be used. Likewise, separate diodes can be used instead of the diode bridges. The reference diodes also can be replaced by any voltage reference device.
It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.
While only several embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that many modifications may be made to the present invention without departing from the spirit and scope thereof.
