# US 2014/0157029 A1 · Power supply circuit

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- Number: US 2014/0157029 A1
- Document ID: US20140157029A1
- Status: Published application
- Kind: A1
- Application number: 14/088,789
- Filed: 2013-11-25
- Published: 2014-06-05
- Earliest claimed: 2012-11-30
- Assignees: Canon Kabushiki Kaisha
- Applicants: Canon Kabushiki Kaisha
- Inventors: Katsumi Takahashi
- Web page: https://patentgrep.com/patent/US20140157029A1

## CPC

- G06F 1/263: {Arrangements for using multiple switchable power supplies, e.g. battery and AC (G06F1/30 takes precedence)}
- G06F 1/32: Means for saving power
- G06F 1/3284: {Power saving in printer}
- H04N 1/00896: {using a low-power mode, e.g. standby}
- Y02D 10/00: Energy efficient computing, e.g. low power processors, power management or thermal management
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE

## Abstract

A power supply circuit includes a first power supply for a normal power mode, a second power supply for a power saving mode, which is connected in parallel with the first power supply, a controller to which power from the first power supply and power from the second power supply are supplied via a common connection point, and a switch element which is connected between an output terminal of the first power supply and the connection point and controls power that is supplied to the controller, wherein the switch element includes a diode between a source terminal and a drain terminal of the switch element, the drain terminal of the switch element is connected to the first power supply side to prevent current flowing from the connection point toward the first power supply, and the source terminal of the switch element is connected to the connection point side.

## Claims

### Claim 1

A power supply circuit for an apparatus that operates in a normal power mode and in a power saving mode, in which power consumption is less than in the normal power mode, the power supply circuit comprising:
a first power supply configured to supply power to the apparatus when the apparatus operates in the normal power mode;
a second power supply, which has a lower power supply capability than the first power supply and is connected in parallel with the first power supply, configured to supply power to the apparatus at least when the apparatus operates in the power saving mode;
a controller to which power from the first power supply and power from the second power supply are supplied via a common connection point; and
a switch element, which is connected between an output terminal of the first power supply and the connection point, configured to control power that is supplied to the controller,
wherein the switch element includes a diode between a source terminal and a drain terminal of the switch element,
the drain element of the switch element is connected to the first power supply side to prevent current flowing from the connection point toward the first power supply, and
the source terminal of the switch element is connected to the connection point side.

### Claim 2 (depends on 1)

The power supply circuit according to claim 1, wherein the switch element is a p-channel type field-effect transistor.

### Claim 3 (depends on 1)

The power supply circuit according to claim 1, further comprising:
a second switch element, which is connected between an output terminal of the second power supply and the connection point, configured to control power that is supplied to the controller; and
a second diode, which is connected between the second power supply and the connection point in series with the second switch element, configured to prevent current flowing from the connection point to the second power supply.

### Claim 4 (depends on 3)

The power supply circuit according to claim 3, wherein the second switch element is configured from a field-effect transistor,
a source terminal of the second switch element is connected to the second power supply side, and
a drain terminal of the second switch element is connected to the connection point side.

### Claim 5 (depends on 1)

The power supply circuit according to claim 1, wherein the switch element is controlled by a signal from the controller.

### Claim 6 (depends on 1)

The power supply circuit according to claim 1, further comprising:
a cutoff unit configured to cut an alternating voltage that is supplied to the first power supply,
wherein the controller is configured to cause the cutoff unit to cut the alternating voltage that is supplied to the first power supply when the apparatus operates in the power saving mode.

### Claim 7 (depends on 1)

The power supply circuit according to claim 1, wherein the controller is configured to stop supply of power from the second power supply to the controller when the apparatus operates in the normal power mode.