Imaging Element Pixel Circuit Size Reduction via Shared Readout

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Solution Overview

Problem

Existing distance measurement devices require a counter circuit and time integrator circuit for each pixel, resulting in a larger circuit size per pixel, which limits the miniaturization and efficiency of the imaging element.

Innovation Solution

Incorporating a light-receiving element, a storage element, and a constant current source device that outputs a constant current from the start to the end of exposure, eliminating the need for a counter circuit and time integrator circuit per pixel, allowing for a smaller pixel size and improved distance measurement precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If each pixel includes a counter circuit and a time integrator circuit, then distance measurement function is achieved, but the circuit size per pixel increases

Engineering Contradiction:

Improvedistance measurement capabilityVSAvoidcircuit size per pixel

Core Design Contradiction:

Measurement precisionVSArea of moving object

Solution Approach 1:

The patent merges the functions of multiple pixels into a shared readout circuit system. Instead of each pixel having its own counter and time integrator, multiple pixels share common readout circuits that perform counting and time integration functions collectively, thereby reducing the circuit size per pixel while maintaining distance measurement capability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The readout circuit is designed with multi-functionality to serve multiple pixels. The same readout circuit can handle signals from different pixels and perform various operations (counting, time integration, distance calculation) that would otherwise require separate dedicated circuits for each pixel

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 configuration reduces the size per pixel, enabling higher precision and longer distance measurement capabilities while improving the signal-to-noise ratio and increasing the number of simultaneously measurable pixels, thus enhancing the overall performance of the distance measurement device.

Implementation Method 1

a detector array including a single-photon detector that outputs detection signals indicating the respective arrival times of a plurality of incoming photons

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Implementation Method 2

a constant current source device configured to output a constant current to the storage element from the start of exposure of the pixels to the end of the exposure

Methodology Applied

Scientific EffectElectrical Conduction: Conduction (electrical)

Data Source

PatentUS20240251183A1Imaging element and ranging device

Publication Date: 2024.07.25 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A distance measurement device includes a plurality of pixels. Each of the pixels includes a light-receiving element, a capacitor, and a constant current source device that outputs a constant current to the capacitor from the start of exposure of the pixel until light is detected by the light-receiving element.