Oxide Semiconductor Photosensor Pulsed Gate Voltage
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Solution Overview
Problem
Existing photosensors using oxide semiconductors require frequent refreshing operations to measure illuminance, which consumes significant power and is not practical for continuous light measurement.
Innovation Solution
A photosensor design that applies a negative gate voltage in a pulsed manner to a transistor with an oxide semiconductor channel, eliminating the need for refreshing operations and allowing for continuous light measurement with reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a photosensor using oxide semiconductor is used for light measurement, then light detection capability is improved, but frequent refreshing operations are required which increases power consumption
Solution Approach 1:
The patent applies periodic pulsing to the gate voltage instead of continuous voltage application. By periodically pulsing the gate voltage, the photosensor can maintain its light detection capability while significantly reducing power consumption during intervals when pulsing is not active. This periodic action allows the system to refresh the measurement at intervals rather than continuously, resolving the contradiction between measurement capability and power consumption.
Solution Approach 2:
The patent utilizes the inherent photoconductive properties of oxide semiconductor materials that automatically maintain their electrical characteristics in response to light exposure without requiring external refreshing operations. The material's self-sustaining photoconductive effect allows continuous light measurement without frequent manual or system-initiated refreshing, thereby reducing power consumption while maintaining measurement accuracy.
2Reliability
If refreshing operation is performed frequently to maintain measurement accuracy, then measurement reliability is improved, but power consumption increases significantly
Solution Approach 1:
The gate voltage is applied in periodic pulses rather than continuously. This periodic action maintains measurement reliability by regularly updating the light detection capability while consuming power only during the pulse intervals. The system can adjust the pulse frequency to balance between measurement reliability and power consumption based on application requirements.
Solution Approach 2:
The patent changes the operational parameters of the photosensor by applying variable voltage levels in pulsed manner. By dynamically adjusting voltage parameters only when needed (during pulses) and maintaining lower power states between pulses, the system preserves measurement reliability while minimizing overall power consumption.
3Productivity
If continuous light measurement is implemented, then productivity is improved, but power consumption becomes excessive
Solution Approach 1:
The system implements continuous light measurement capability through periodic pulsing of the gate voltage. During each pulse interval, the photosensor actively measures light, and between pulses, it maintains a low-power state. This approach enables continuous monitoring functionality while keeping average power consumption low, as the system cycles between active measurement and standby states.
Solution Approach 2:
The patent maintains continuous useful action for light measurement by implementing a pulsed measurement cycle that continuously monitors light conditions. Rather than having discrete measurement events, the periodic pulsing creates a continuous measurement stream where the photosensor is always ready to detect light changes, providing continuous productivity while managing power consumption through the pulsed operation mode.
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 high-speed and low-power light measurement, suitable for applications like large-sized flat panel displays and RFID devices, with the ability to adjust luminance continuously without frequent recalibration.
Implementation Method 1
it is well known that conductivity of an oxide semiconductor changes by reception of light
Data Source
AI summary
An object is to provide a photosensor utilizing an oxide semiconductor in which a refreshing operation is unnecessary, a semiconductor device provided with the photosensor, and a light measurement method utilizing the photosensor. It is found that a constant gate current can be obtained by applying a gate voltage in a pulsed manner to a transistor including a channel formed using an oxide semiconductor, and this is applied to a photosensor. Since a refreshing operation of the photosensor is unnecessary, it is possible to measure the illuminance of light with small power consumption through a high-speed and easy measurement procedure. A transistor utilizing an oxide semiconductor having a relatively high mobility, a small S value, and a small off-state current can form a photosensor; therefore, a multifunction semiconductor device can be obtained through a small number of steps.