Adjustable High Voltage Power Apparatus for Color Laser Printers

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Solution Overview

Problem

Conventional power apparatuses for high voltage in color laser beam printers have a fixed AC output potential, which cannot be automatically adjusted to accommodate the complex process conditions, limiting the flexibility and picture quality in color laser beam printing.

Innovation Solution

A power apparatus that includes a first signal processing unit to filter and adjust a PWM signal, and a second signal processing unit to compare and convert the signal into a high voltage, allowing for variable output potential by adjusting the duty cycle of the inputted PWM signals, using an RC low pass filter, comparator, switching controller, and amplifier.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a fixed reference potential is used in the comparator, then the circuit structure is simple, but the AC output potential cannot be adjusted

Engineering Contradiction:

Improveoutput potential adjustabilityVSAvoidcircuit structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies dynamics by making the reference potential adjustable through a DAC (Digital to Analog Converter) controlled by a CPU. Instead of a fixed reference potential, the system can dynamically change the reference potential value based on external control signals, enabling the AC output potential to be adjusted without fundamentally changing the circuit topology.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of reference potential from a fixed value to a variable value that can be programmed via DAC. By modifying the reference potential parameter through digital control, the system achieves adjustable AC output potential while maintaining the basic comparator circuit structure.

Inventive Principle:

Principle #35Parameter changes

2Extent of automation

If variable resistors are connected to adjust reference potential, then output potential can be adjusted, but automatic variation during operation is impossible

Engineering Contradiction:

Improveautomatic potential adjustmentVSAvoidmanual adjustment requirement

Core Design Contradiction:

Extent of automationVSEase of operation

Solution Approach 1:

The patent implements feedback control by allowing the CPU to monitor and adjust the DAC output based on operational conditions. The system can automatically vary the reference potential (and thus the AC output potential) during operation by receiving feedback signals and adjusting the PWM duty cycle accordingly, eliminating the need for manual resistor adjustment.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces the mechanical adjustment of variable resistors with an electronic control system using DAC and PWM modulation. This substitution enables automatic adjustment through digital signals from the CPU, eliminating the need for physical manual adjustment while maintaining ease of operation through software control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If PWM duty cycle is varied to adjust output, then flexibility is improved, but the AC output potential remains fixed in conventional circuits

Engineering Contradiction:

Improveoutput potential variabilityVSAvoidoutput stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-calculating and setting the appropriate PWM duty cycle and reference potential values before operation begins. The CPU can program the DAC and control the PWM generator to output signals with predetermined characteristics, ensuring both flexibility in potential adjustment and stability in output delivery during actual operation.

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables effective adjustment of the development concentration and improves picture quality in color laser beam printers by varying the output potential, adapting to complex printing conditions and environments.

Implementation Method 1

an RC low pass filter (LPF) low-pass filtering the second signal and outputting the filtered second signal at a DC level

Methodology Applied

Scientific EffectRC low pass filtering: Filter (electronic)

Implementation Method 2

a comparator dividing a voltage of the second signal having the DC level to set a reference potential, comparing the reference potential with the first signal and outputting a result indicative thereof

Methodology Applied

Scientific EffectVoltage comparison:

Implementation Method 3

a switching controller switching a potential V2 to be output as the peak-to-peak of the first signal

Methodology Applied

Scientific EffectElectrical switching:

Implementation Method 4

a TRANS amplifying the pulse waveform of the potential V2 from the switching controller and outputting the amplified potential V2 as the amplified voltage

Methodology Applied

Scientific EffectSignal amplification:

Data Source

PatentUS7630215B2Power apparatus and method to provide high voltage

Publication Date: 2009.12.08 HEWLETT PACKARD DEVELOPMENT COMPANY LP

AI summary

A power apparatus and method thereof include first and second signal processing units. The first signal processing unit filters and adjusts a first inputted PWM signal in a predetermined bandwidth to set a reference potential. The second signal processing unit compares the reference potential with a second inputted PWM signal, varies a power to be output according to a result of the comparison, converts the power into a high power, and outputs the converted power.