PWM Controller Synchronizes Voltage Measurement to Stabilize Display Luminance
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Solution Overview
Problem
Existing electronic devices using pulse width modulation (PWM) control for luminance adjustment in display units experience unwanted output changes due to voltage fluctuations in the power line, especially when the voltage measurement terminal is connected in parallel with the power source, leading to unnecessary changes in display luminance even without user operation.
Innovation Solution
An electronic device with a variable resistor, a power source, and a controller that acquires voltage information to generate a PWM signal with a determined duty ratio, synchronizing the voltage measurement with the PWM cycle to prevent unwanted voltage changes, thereby stabilizing the luminance output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the voltage measurement terminal is connected to the power line in parallel with the power source, then the device structure is simplified and cost is reduced, but voltage fluctuations occur in the power line causing unwanted luminance changes
Solution Approach 1:
The controller performs preliminary action by acquiring voltage information at a specific timing (when PWM output is high) before using it for luminance control. This timing selection prevents the controller from detecting voltage fluctuations caused by PWM switching, thereby maintaining luminance stability without changing the circuit connection structure
Solution Approach 2:
The controller operates periodically by acquiring voltage information at regular intervals synchronized with the PWM cycle. This periodic acquisition at specific phases (when PWM is high) filters out unwanted voltage variations and ensures stable luminance control while maintaining the simplified parallel connection structure
2Use of energy by moving object
If PWM control is applied to adjust luminance, then energy efficiency is improved, but voltage drops in the power line cause unwanted output changes
Solution Approach 1:
The controller performs preliminary action by acquiring voltage information at a specific timing (when PWM output is high) before using it for luminance control. This timing selection prevents the controller from detecting voltage fluctuations caused by PWM switching, thereby maintaining luminance stability without changing the circuit connection structure
Solution Approach 2:
The controller uses feedback by continuously acquiring voltage information and adjusting PWM duty ratio based on the acquired voltage. The feedback mechanism compensates for voltage drops in the power line by adjusting the duty ratio dynamically, maintaining stable luminance output while preserving PWM energy efficiency
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
This solution effectively reduces or prevents flickering and unnecessary luminance changes in the display unit, maintaining stable output without additional hardware, thus enhancing user experience and reducing operational costs.
Implementation Method 1
a variable resistor of which a resistance value changes in accordance with a user operation
Implementation Method 2
outputs a pulse width modulation (PWM) signal for turning on or off the load, the PWM signal having a duty ratio determined based on the acquired information
Data Source
AI summary
An image formation device is provided which includes a variable resistor of which a resistance value changes in accordance with a user operation, an A/D converter that outputs information relating to a voltage applied to the variable resistor, and a pulse width modulation (PWM) controller that outputs a PWM signal having a duty ratio determined based on the information output by the A/D converter. The PWM controller outputs the PWM signal that has the duty ratio determined based on the information input with reference to a timing for inverting a logic state of the PWM signal.