Image Forming Apparatus Low Power USB Communication

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Solution Overview

Problem

Existing image forming apparatuses face challenges in implementing low power modes without disrupting USB communication, as cutting off power to external DRAM prevents USB driver operation, leading to communication issues and incorrect device state detection.

Innovation Solution

An image forming apparatus with a control unit that manages both low power and normal modes by using separate memory units and power supply management, allowing conversion to normal mode upon signal input through the data interface unit and processing interrupts, while maintaining power to a sub-controller for low power mode operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by stationary object

If power supply is cut off to external DRAM to enter low power mode, then standby power consumption is reduced, but USB driver operation stops and communication through USB becomes impossible

Engineering Contradiction:

Improvestandby power consumptionVSAvoidUSB communication functionality

Core Design Contradiction:

Use of energy by stationary objectVSReliability

Solution Approach 1:

The patent segments the memory system into two separate memory units: external DRAM for normal mode operation and internal SRAM for low power mode operation. This segmentation allows the system to maintain USB communication functionality in low power mode by keeping a minimal USB driver in the internal SRAM while cutting power to the external DRAM, thus resolving the contradiction between reducing standby power and maintaining USB communication capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent extracts the essential USB driver functionality into a minimal version that can operate from internal SRAM with reduced power consumption. This extracted minimal USB driver is sufficient to maintain basic USB communication and device state monitoring, allowing the system to cut power to the full external DRAM while preserving USB functionality.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If large-capacity SRAM is used to implement USB driver in low power mode, then USB communication is maintained, but cost increases significantly

Engineering Contradiction:

ImproveUSB driver operation in low power modeVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies partial action by implementing only the minimal necessary USB driver functionality in the internal SRAM rather than the full-featured USB driver. This minimal USB driver is sufficient to maintain basic USB communication and device state monitoring, significantly reducing the memory capacity requirement and thus the cost of internal SRAM while preserving essential USB functionality in low power mode.

Inventive Principle:

Principle #16Partial or excessive action

3Reliability

If external DRAM operates normally in low power mode to maintain USB communication, then USB driver functionality is preserved, but standby power consumption increases

Engineering Contradiction:

ImproveUSB communication capabilityVSAvoidstandby power consumption

Core Design Contradiction:

ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The patent changes the operational parameters by switching between two distinct memory units based on the power mode. In low power mode, the system transitions from using external DRAM to using internal SRAM, changing the memory technology parameter to achieve lower power consumption while maintaining USB communication capability. This parameter change allows the system to optimize for low power consumption without sacrificing USB functionality.

Inventive Principle:

Principle #35Parameter changes

4Measurement precision

If PC monitors device state through USB in low power mode, then device state can be detected, but PC may incorrectly recognize device as turned off or connection cut

Engineering Contradiction:

Improvedevice state detection accuracyVSAvoiddevice state recognition accuracy

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent implements feedback mechanisms where the minimal USB driver in internal SRAM actively maintains USB communication and device state monitoring even in low power mode. This continuous feedback ensures that the PC can accurately detect the device state through USB, preventing incorrect recognition of the device as turned off or connection cut, while still achieving low power consumption by using the minimal USB driver instead of the full external DRAM-based driver.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS9736326B2Image forming apparatus and low power driving method thereof

Publication Date: 2017.08.15 HEWLETT PACKARD DEVELOPMENT COMPANY LP

AI summary

An image forming apparatus having a USB communication function includes a control interface unit to perform USB control communication, a data interface unit to perform USB data communication, and a control unit to perform an event in a low power mode according to a signal input through the control interface unit, and to perform an event in a normal mode according to a signal input through the control interface unit and the data interface unit. Therefore, the low power mode may be effectively implemented.