Solid-State Imaging Driver Circuit Synchronization

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Solution Overview

Problem

Existing solid-state imaging devices face challenges in synchronizing the global shutter function across all pixels due to varying wiring resistance, leading to potential lag in drive timing and reduced precision in distance measurement, especially for applications requiring high-speed operation.

Innovation Solution

The implementation of a driver circuit with capacitors and switch transistors that manage voltage supply to pixels, minimizing wiring length and parasitic components, allowing for simultaneous exposure of all pixels with reduced lag and increased speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a global shutter function is implemented to enable simultaneous exposure of all pixels, then distance measurement precision is improved, but wiring resistance variations cause lag in drive timing across different pixel positions

Engineering Contradiction:

Improvedistance measurement precisionVSAvoiddrive timing synchronization

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The driver circuit pre-charges capacitors before the global shutter activation. The first capacitor is charged from the first voltage source and the second capacitor is charged from the second voltage source before the switching operation. This preliminary charging action ensures that when the switches are activated simultaneously, both capacitors can discharge equally to drive the pixels, compensating for the wiring resistance differences and achieving synchronized pixel activation across all positions.

Inventive Principle:

Principle #10Preliminary action

2Speed

If wiring length is reduced to minimize parasitic components, then pixel driving speed is improved, but device layout complexity increases

Engineering Contradiction:

Improvepixel driving speedVSAvoiddriver circuit layout complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The driver circuit is segmented into multiple independent driver circuit units, with each unit responsible for driving a specific row of pixels. Each driver circuit unit includes its own first capacitor, second capacitor, first switch transistor, and second switch transistor. This segmentation allows each unit to operate independently with minimized wiring length to its assigned pixels, reducing parasitic inductance and resistance while maintaining overall system functionality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Capacitors are introduced as intermediary energy storage elements between the voltage sources and the pixel switches. The first capacitor and second capacitor act as mediators that store electrical energy and release it simultaneously when the switch transistors are activated. This intermediary mechanism allows the voltage sources to be physically distant from the pixels while still achieving fast, synchronized driving, as the capacitors are positioned close to the switch transistors with minimal wiring length.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11965987B2Solid-state imaging device, distance measuring device, and distance measuring method

Publication Date: 2024.04.23 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A driver circuit includes: a first node connected to a first signal line; a first switch transistor provided between a first power supply and a first capacitor; a second switch transistor provided between a second power supply and a second capacitor; a third switch transistor provided between the first capacitor and the first node; and a fourth switch transistor provided between the second capacitor and the first node.