Electrical transmission or interconnection systems – Plural supply circuits or sources – Substitute or emergency source
Reexamination Certificate
1999-03-31
2001-09-11
Jackson, Stephen W. (Department: 2836)
Electrical transmission or interconnection systems
Plural supply circuits or sources
Substitute or emergency source
C307S066000
Reexamination Certificate
active
06288455
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to electric equipment requiring supply of backup electric power during an OFF state of a power supply switch, and power supply circuit structures for use in such electric equipment.
In recent years, numerous pieces of electric equipment containing a microcomputer and semiconductor memory have been in practical use. In electric equipment of this type, like DSP amplifiers, the semiconductor memory, such as a SRAM (Static Random Access Memory), provided within or separately from the microcomputer normally requires supply of backup electric power to retain at least part of its storage function even after the power supply switch of the equipment is turned OFF.
Typical examples of the conventionally-known backup power supply scheme include the following.
(a) One where, as shown in
FIG. 7
, when a power supply switch SW connected with the primary winding of a transformer T is turned OFF, electric charge stored in a capacitor or condenser C connected with the secondary winding (or a separate secondary cell) is used as a backup power supply for a microcomputer and the like.
(b) One where, as shown in
FIG. 8
, a sub-transformer T
2
is provided, separately from a transformer T of the main power supply, to comprise an auxiliary or backup power supply. Here, the primary winding of the sub-transformer is connected to a supply plug at a point closer than a power supply switch SW. Thus, even after the power supply switch SW is turned OFF, the backup power supply remains active as long as the plug is maintained in connection to the electric outlet.
(c) A compromise between the above-mentioned two schemes, where the sub-transformer provides a power backup while the supply plug is in connection to the electric outlet, and the condenser is caused to provide a power backup only when the supply plug is disconnected from the electric outlet.
However, the above-mentioned three conventional backup power supply schemes are not satisfactory for the following reasons. First, the scheme mentioned in item (a) above presents the problem that if the power supply switch remains turned OFF for a long time period, the condenser etc. would discharge electricity to thereby invite an unwanted loss of stored data although no substantial electricity is consumed by the backup power supply. In addition, deterioration of the condenser etc., occurring with the passage of time, would lead to a reduced backup time. Therefore, the other two schemes employing the sub-transformer, mentioned in items (b) and (c) above, are more popular nowadays.
But, with the item (b) and (c) schemes, there is encountered the problem that substantial electricity consumption by the sub-transformer is unavoidable, even though the power backup can be retained as long as the plug is kept in connection with the electric outlet. While the necessary power consumption for retaining stored data in the microcomputer etc. is nominal, usually on the order of &mgr;A at most, the exciting current has to be constantly supplied to the sub-transformer even during an OFF state of the power supply switch, which would result in a power loss as great as several hundred mW that can never be ignored from the viewpoint of energy conservation.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a power supply circuit structure which, during an OFF state of a power supply switch, can supply stable backup power with a minimized power loss, as well as well-performing electric equipment using such a power supply circuit structure.
According to one aspect of the present invention, there is provided a power supply circuit structure which comprises a main power supply system for supplying main electric power to electric equipment and an auxiliary power supply system for supplying backup auxiliary power to the electric equipment during an OFF state of the main power supply system, and which is characterized in that the main power supply system includes main power supply circuitry, a transformer that delivers a.c. power introduced via a supply plug to the main power supply circuitry and a power supply switch provided between a primary winding of the transformer and the supply plug, and the auxiliary power supply system includes auxiliary power supply circuitry and a certified condenser that satisfies a predetermined safety requirement and delivers the a.c. power introduced via the supply plug to the auxiliary power supply circuitry without intervention of the power supply switch.
Here, the term “certified condenser” refers to a ceramic condenser, film condenser or the like which satisfies at least one of four international safety requirements: UL(UL1414); CSA(C22.2 No.0, No.1); BSI(BS EN60065(1994)); and IEC384-14 Version 2(1993) and whose stable operation is guaranteed under a rated voltage of, say, 125 VAC.
In a situation where the supply plug has none of its terminals specified as a grounding terminal, the auxiliary power supply circuitry preferably includes a fill-wave rectifier circuit that rectifies the a.c. power supplied via the certified condenser from the supply plug. Conversely, in a situation where the supply plug has one of its terminals specified as a grounding terminal, the auxiliary power supply circuitry preferably includes a half-wave rectifier circuit which is made up of a rectifying diode that half-wave rectifies the a.c. power supplied via the certified condenser from a non-grounding terminal of the supply plug and a charge-pumping diode that is connected between a connection node, located between the rectifying diode and the certified condenser, and the grounding terminal of the supply plug.
In a case where such a power supply circuit structure is applied to electric equipment, it further comprises a remote-controlling power supply system including: a control circuit that receives a radio signal from a remote controller and outputs a power supply control signal based on the radio signal; a remote-controlling power supply circuit that supplies the control circuit with electric power necessary for operation of the control circuit; a sub-transformer that delivers the a.c. power introduced via the supply plug to the remote-controlling power supply circuit; and a power supply switch provided between a primary of the transformer and the supply plug. In this case, turning-ON/OFF of the power supply switch in the main power supply system is controlled in accordance with the power supply control signal outputted by the control circuit.
The present invention further provides electric equipment which comprises: principal circuitry that is supplied with electric power only when a power supply is in an ON state; a main power supply system for supplying main electric power to the principal circuitry; auxiliary circuitry that has to be supplied with the electric power even when the power supply is in an OFF state; and an auxiliary power supply system for supplying backup auxiliary power to the auxiliary circuitry during the OFF period of the power supply, and which is characterized in that the main power supply system includes main power supply circuitry, a transformer that delivers a.c. power introduced via a supply plug to the main power supply circuitry and a power supply switch provided between a primary winding of the transformer and the supply plug, and the auxiliary power supply system includes auxiliary power supply circuitry and a certified condenser that satisfies a predetermined safety requirement and delivers the a.c. power introduced via the supply plug to the auxiliary power supply circuitry without intervention of the power supply switch.
According to the present invention, the necessary backup power can be given, without employing a sub-transformer, even during the OFF state of the power supply switch by the auxiliary power supply circuit that uses the a.c. power extracted via the certified condenser. The certified condenser is not allowed to have very great capacity due to safety requirements, so that it is normally not possible to extract great electric po
DeBeradinis Robert L.
Jackson Stephen W.
Pillsbury & Winthrop LLP
Yamaha Corporation
LandOfFree
Power supply circuit structure and electric equipment using... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Power supply circuit structure and electric equipment using..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Power supply circuit structure and electric equipment using... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2501025