Imaging Device Variable-Voltage Power Source Control
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Solution Overview
Problem
Existing imaging devices using semiconductor light-emitting elements face challenges in efficiently controlling the power source voltage to minimize power loss and ensure consistent light emission, as the forward voltage of the light-emitting element can vary due to individual device differences, aging, and temperature changes, making it difficult to determine the optimal voltage margin.
Innovation Solution
An imaging device with a variable-voltage power source, a constant current-driving circuit, and a control circuit that uses pulse-width modulation and voltage clipping to control the driving voltage, applying a voltage greater than or equal to the compliance voltage of the light-emitting element, and adjusts the voltage based on the voltage drop and brightness of the image, to optimize power usage and maintain proper light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power source voltage VDD is increased to ensure sufficient current flow, then the light emission reliability is improved, but the power loss in the constant current-driving circuit increases
Solution Approach 1:
The patent implements feedback control by detecting the actual forward voltage of the light-emitting element and adjusting the power source voltage VDD accordingly. The control circuit monitors the voltage drop across the light-emitting element and dynamically modifies VDD to maintain the voltage margin Vmgn at an optimal level, preventing both insufficient current flow and excessive power loss.
Solution Approach 2:
The patent transitions from a static power source voltage to a dynamic voltage control system. The power source voltage VDD is continuously adjusted based on the detected forward voltage characteristics of the light-emitting element, allowing the system to adapt to changes in device characteristics, temperature, and aging while optimizing the balance between reliability and power efficiency.
2Loss of energy
If the power source voltage VDD is decreased to minimize power loss, then the energy efficiency is improved, but the current flow becomes insufficient
Solution Approach 1:
The control circuit continuously monitors the forward voltage of the light-emitting element and adjusts the power source voltage VDD in real-time. This feedback mechanism ensures that VDD is always sufficient to maintain proper current flow while minimizing the voltage margin Vmgn and thereby reducing power loss in the constant current-driving circuit.
Solution Approach 2:
The patent dynamically changes the power source voltage parameter VDD based on the detected forward voltage characteristics. By adjusting this critical parameter, the system optimizes the balance between ensuring sufficient current flow and minimizing power loss, adapting to individual device variations and operating conditions.
3Device complexity
If a fixed power source voltage VDD is used, then the device complexity is reduced, but the adaptability to individual device differences and aging deteriorates
Solution Approach 1:
The patent introduces a feedback control mechanism that detects the actual forward voltage of the light-emitting element and adjusts the power source voltage accordingly. This feedback system enables the device to adapt to individual variations, aging effects, and temperature changes while maintaining consistent light emission performance.
Solution Approach 2:
The control circuit performs preliminary detection of the forward voltage characteristics and pre-adjusts the power source voltage before light emission begins. This preliminary action ensures that the voltage is optimally set for the specific device characteristics, preventing performance degradation due to individual differences or aging.
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 minimizes power loss in the constant current-driving circuit, ensures consistent light emission, and adapts to variations in the light-emitting element's characteristics by dynamically controlling the voltage, thereby improving the efficiency and reliability of the imaging device.
Implementation Method 1
a light-emitting element 5... drives the light-emitting element 5 and causes the light-emitting element 5 to emit light
Data Source
AI summary
An imaging device according to an embodiment includes an imaging circuit, a variable-voltage power source, a light-emitting element, a constant current-driving circuit, and a control circuit. The control circuit is configured to turn on the light-emitting element in a period during which the imaging circuit performs imaging. The control circuit is configured to turn off the light-emitting element in a period during which the imaging circuit does not perform imaging. The control circuit is configured to control voltage applied to the light-emitting element by the variable-voltage power source on the basis of voltage of an input terminal of the constant current-driving circuit when the light-emitting element is turned on. The control circuit is configured to control the variable-voltage power source and apply predetermined voltage greater than or equal to compliance voltage of the light-emitting element to the light-emitting element when the light-emitting element is turned off.