# US 8,542,064 B2 · Methods and apparatus to control power in a printer

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- Number: US 8,542,064 B2
- Document ID: US8542064B2
- Status: Granted
- Kind: B2
- Application number: 13/286,112
- Filed: 2011-10-31
- Published: 2013-05-02
- Granted: 2013-09-24
- Earliest claimed: 2011-10-31
- Assignees: Hewlett-Packard Development Company, L.P.
- Applicants: Barley Mark Hirst
- Inventors: Barley Mark Hirst
- Web page: https://patentgrep.com/patent/US8542064B2

## CPC

- G06F 1/26: Power supply means, e.g. regulation thereof (for memories G11C)
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

Methods and apparatus to control power in a printer are disclosed. An example apparatus includes a first field effect transistor having a first terminal, a second terminal, and a third terminal, the second terminal coupled with a first voltage input. The example apparatus further includes a second field effect transistor having a fourth terminal, a fifth terminal, and a sixth terminal, the fourth terminal coupled with the first terminal of the first field effect transistor, the fifth terminal coupled with a second voltage input. The example apparatus further includes a first comparator having a first input coupled to the first input voltage, having a second input coupled to the second input voltage, and having an output coupled with the third terminal.

## Claims

### Claim 1

A circuit to control power in a printer, the circuit comprising:
a first field effect transistor having a first terminal, a second terminal, and a third terminal, the second terminal coupled with a first voltage input;
a second field effect transistor having a fourth terminal, a fifth terminal, and a sixth terminal, the fourth terminal coupled with the first terminal of the first field effect transistor, the fifth terminal coupled with a second voltage input; and
a first comparator having a first input coupled to the first input voltage, the first comparator having a second input coupled to the second input voltage, and the first comparator having a first output coupled with the third terminal via a second comparator, the second comparator having: (1) a third input coupled to a first reference voltage, (2) a fourth input coupled to the output of the first comparator, and (3) an output coupled with the third terminal.

### Claim 2 (depends on 1)

The circuit as described in claim 1, further comprising a third comparator having: (1) a fifth input coupled to a second reference voltage, (2) a sixth input coupled to the second input voltage, and (3) a third output coupled with the sixth terminal.

### Claim 3

A circuit to control power in a printer, the circuit comprising:
a first field effect transistor having a first terminal, a second terminal, and a third terminal, the second terminal coupled with a first voltage input;
a second field effect transistor having a fourth terminal, a fifth terminal, and a sixth terminal, the fourth terminal coupled with the first terminal of the first field effect transistor, the fifth terminal coupled with a second voltage input;
a first comparator having a first input coupled to the first input voltage, the first comparator having a second input coupled to the second input voltage, and the first comparator having a first output coupled with the third terminal;
the first field effect transistor is an n-type field effect transistor;
the first terminal is a gate terminal;
the second terminal is a source terminal;
the third terminal is a drain terminal;
the second field effect transistor is an n-type field effect transistor;
the fourth terminal is a gate terminal;
the fifth terminal is a source terminal; and
the sixth terminal is a drain terminal.

### Claim 4

A circuit to control power in a printer, the circuit comprising:
a first field effect transistor having a first terminal, a second terminal, and a third terminal, the second terminal coupled with a first voltage input;
a second field effect transistor having a fourth terminal, a fifth terminal, and a sixth terminal, the fourth terminal coupled with the first terminal of the first field effect transistor, the fifth terminal coupled with a second voltage input;
a first comparator having a first input coupled to the first input voltage, the first comparator having a second input coupled to the second input voltage, and the first comparator having a first output coupled with the third terminal;
the first field effect transistor is a p-type field effect transistor;
the first terminal is a gate terminal;
the second terminal is a source terminal;
the third terminal is a drain terminal;
the second field effect transistor is a p-type field effect transistor;
the fourth terminal is a gate terminal;
the fifth terminal is a source terminal; and
the sixth terminal is a drain terminal.

### Claim 5

A circuit to control power in a printer, the circuit comprising:
a first field effect transistor having a first terminal, a second terminal, and a third terminal, the second terminal coupled with a first voltage input;
a second field effect transistor having a fourth terminal, a fifth terminal, and a sixth terminal, the fourth terminal coupled with the first terminal of the first field effect transistor, the fifth terminal coupled with a second voltage input, the first field effect transistor and the second field effect transistor being arranged in a wired-OR configuration; and
a first comparator having a first input coupled to the first input voltage, the first comparator having a second input coupled to the second input voltage, and the first comparator having a first output coupled with the third terminal.

### Claim 6

An apparatus to control power in a printer, the apparatus comprising:
a comparator to receive a first voltage from a first power supply of a printer and a second voltage from a second power supply of the printer, the comparator to output a first control signal and a second control signal, the comparator to output the first control signal when the first voltage is greater than the second voltage and the first voltage is greater than a first reference voltage, the comparator to output the second control signal when the second voltage is greater than the first voltage and the second voltage is greater than a second reference voltage;
a first switch to receive the first voltage and output a first output voltage to a power converter of the printer based on the first control signal, the first switch having a first intrinsic diode; and
a second switch to receive the second voltage and to output a second output voltage to the converter based on the second control signal, the second switch having a second intrinsic diode, a first cathode of the first intrinsic diode being communicatively coupled with a second cathode of the second intrinsic diode and the power converter.

### Claim 7

An apparatus to control power in a printer, the apparatus comprising:
a comparator to receive a first voltage from a first power supply of a printer and a second voltage from a second power supply of the printer, the comparator to output a first control signal and a second control signal;
a first switch to receive the first voltage and output a first output voltage to a power converter of the printer based on the first control signal, the first switch having a first intrinsic diode, the first intrinsic diode to prevent a current from the second power supply from being passed to the first power supply; and
a second switch to receive the second voltage and to output a second output voltage to the converter based on the second control signal, the second switch having a second intrinsic diode, a first cathode of the first intrinsic diode being communicatively coupled with a second cathode of the second intrinsic diode and the power converter.

### Claim 8

An apparatus to control power in a printer, the apparatus comprising:
a comparator to receive a first voltage from a first power supply of a printer and a second voltage from a second power supply of the printer, the comparator to output a first control signal and a second control signal;
a first switch to receive the first voltage and output a first output voltage to a power converter of the printer based on the first control signal, the first switch having a first intrinsic diode, the power converter of the printer to output power to a load of the printer regardless of a low power state of the printer; and
a second switch to receive the second voltage and to output a second output voltage to the converter based on the second control signal, the second switch having a second intrinsic diode, a first cathode of the first intrinsic diode being communicatively coupled with a second cathode of the second intrinsic diode and the power converter.

### Claim 9 (depends on 8)

The apparatus as described in claim 8, wherein the first power supply is disabled when the printer is in the low power state.

### Claim 10

An apparatus to control power in a printer, the apparatus comprising:
a comparator to receive a first voltage from a first power supply of a printer and a second voltage from a second power supply of the printer, the comparator to output a first control signal and a second control signal;
a first switch to receive the first voltage and output a first output voltage to a power converter of the printer based on the first control signal, the first switch having a first intrinsic diode, the first switch being a field effect transistor configured in a reverse conduction mode; and
a second switch to receive the second voltage and to output a second output voltage to the converter based on the second control signal, the second switch having a second intrinsic diode, a first cathode of the first intrinsic diode being communicatively coupled with a second cathode of the second intrinsic diode and the power converter.

### Claim 11

An apparatus to control power in a printer, the apparatus comprising:
a comparator to receive a first voltage from a first power supply of a printer and a second voltage from a second power supply of the printer, the comparator to output a first control signal and a second control signal;
a first switch to receive the first voltage and output a first output voltage to a power converter of the printer based on the first control signal, the first switch having a first intrinsic diode, the first intrinsic diode being a parasitic body diode: and
a second switch to receive the second voltage and to output a second output voltage to the converter based on the second control signal, the second switch having a second intrinsic diode, a first cathode of the first intrinsic diode being communicatively coupled with a second cathode of the second intrinsic diode and the power converter.

### Claim 12

An apparatus to control power in a printer, the apparatus comprising:
a comparator to receive a first voltage from a first power supply of a printer and a second voltage from a second power supply of the printer, the comparator to output a first control signal and a second control signal;
a first switch to receive the first voltage and output a first output voltage to a power converter of the printer based on the first control signal, the first switch having a first intrinsic diode; and
a second switch to receive the second voltage and to output a second output voltage to the converter based on the second control signal, the second switch having a second intrinsic diode, a first cathode of the first intrinsic diode being communicatively coupled with a second cathode of the second intrinsic diode and the power converter, the first intrinsic diode and the second intrinsic diode to function as a wired-OR by providing power to the power converter of the printer until the at least one of the first control signal and the second control signal are generated.