Capacitive Coupling Bidirectional Diode for Sensor Electrostatic Protection
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Solution Overview
Problem
Existing electro-optical devices face challenges in achieving high-accuracy detection of environmental conditions like illuminance due to leakage currents from bidirectional diode elements used for static electricity protection, which also decrease productivity and may not be separable at all positions.
Innovation Solution
The integration of capacitive-coupling-operation bidirectional diode elements on the element substrate, which include semiconductor elements and capacitor elements, allows for electrostatic protection without affecting signal output from sensor elements, enabling high-accuracy detection and early-stage manufacturing protection against static electricity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bidirectional diode element is used to electrically connect the sensor signal line to the common wiring line for electrostatic protection, then the sensor elements are protected from static electricity, but leakage current from the bidirectional diode element affects the sensor output signals, resulting in low detection accuracy
Solution Approach 1:
The bidirectional diode element is divided into two separate diode elements connected in opposite directions between the sensor signal line and the common wiring line. This segmentation allows each diode element to be independently controlled, enabling one to remain in non-conducting state during normal operation (preventing leakage current) while the other provides electrostatic protection when needed.
Solution Approach 2:
The electrical state of the bidirectional diode element is made dynamic through independent gate voltage control. By applying appropriate gate voltages to each diode element, the system can switch between non-conducting state (for accurate sensing) and conducting state (for electrostatic discharge), adapting to different operational requirements.
2Measurement precision
If the bidirectional diode element is separated at the final stage of the manufacturing process to eliminate leakage current effects, then detection accuracy is improved, but productivity decreases due to the additional separating step
Solution Approach 1:
The bidirectional diode element structure is designed and prepared in advance during the main manufacturing process, with both diode elements formed and positioned on the substrate. The independent gate control mechanism is pre-established, allowing the system to achieve accurate sensing without requiring post-manufacturing separation steps.
Solution Approach 2:
The electrical characteristics of the bidirectional diode element are controlled by changing the gate voltage parameter. By adjusting the gate voltage to keep both diode elements in non-conducting state during normal operation, the system eliminates leakage current effects without any physical separation or modification of the manufactured structure.
3Productivity
If the bidirectional diode element is kept intact without separation, then manufacturing productivity is maintained, but the bidirectional diode element may not be separated depending on position, leaving leakage current affecting sensor signals
Solution Approach 1:
Gate voltage control serves as an intermediary mechanism between the bidirectional diode element and the sensor signal line. By using the gate electrode as a mediator, the system can dynamically control the electrical state of the diode elements, blocking leakage current paths when needed while maintaining the physical integrity of the manufactured structure.
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 enables high-accuracy detection of environmental conditions while protecting sensor elements from static electricity, maintaining productivity by allowing the capacitive-coupling-operation bidirectional diode elements to be finished early in the manufacturing process, thus preventing signal interference and ensuring reliable electrostatic discharge.
Implementation Method 1
a capacitive-coupling-operation bidirectional diode element (1d) having a structure in which capacitor elements (1z) are arranged between gate electrodes (3d) and drain electrodes (6g)
Implementation Method 2
the sensor signal line is electrically connected to the common wiring line via the capacitive-coupling-operation bidirectional diode element... protecting the sensor elements against static electricity
Data Source
AI summary
An electro-optical device includes pixel regions arranged at intersections of a plurality of data lines and a plurality of scanning lines on an element substrate. A sensor element, a sensor signal line for outputting a signal from the sensor element, a common wiring line, and a capacitive-coupling-operation bidirectional diode element are disposed at an end of a region on the element substrate in which the pixel regions are arranged. The capacitive-coupling-operation bidirectional diode element includes two capacitive-coupling-operation diode elements each including a semiconductor element including a source electrode, a drain electrode, a semiconductor layer having a channel region, and a gate electrode facing the channel region with a gate insulating film disposed therebetween, and a capacitor element arranged between one of the source electrode and the drain electrode and the gate electrode.