Pseudo 4-Tap Pixel Structure for Depth Measurement

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Solution Overview

Problem

Existing depth measurement systems using time-of-flight (TOF) schemes require large memory areas due to the need for two frames to suppress background light, leading to increased area occupation and low frame rates, which hinder system performance and cost-effectiveness.

Innovation Solution

A pseudo 4-tap pixel structure is employed, utilizing a delta sigma circuit to calculate delta values from a single frame, eliminating the need for frame memories and enabling depth information calculation with improved frame rates without increasing chip area.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If two frames are used to suppress background light in TOF depth measurement, then background light suppression is improved, but memory area occupation increases and frame rate decreases

Engineering Contradiction:

Improvebackground light suppressionVSAvoidmemory area occupation

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent merges the functionality of two separate frame memories into a single frame memory by alternately storing even rows in the first half of the memory and odd rows in the second half. This combining approach maintains the capability to suppress background light while reducing the total memory area required, directly resolving the contradiction between reliability and memory area occupation.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent implements dynamic row selection and memory addressing where even rows and odd rows are alternately processed and stored in different memory regions. This dynamic approach allows the system to achieve background light suppression with only one frame memory, improving both memory efficiency and frame rate while maintaining reliability.

Inventive Principle:

Principle #15Dynamics

2Reliability

If two frames are used to suppress background light in TOF depth measurement, then background light suppression is improved, but frame rate decreases

Engineering Contradiction:

Improvebackground light suppressionVSAvoidframe rate

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent employs periodic action by alternately capturing even rows and odd rows in a single frame, processing them in an interleaved manner. This periodic processing allows background light suppression to be achieved without waiting for two complete frames, thereby maintaining high frame rate while ensuring reliable background light suppression.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system dynamically processes even and odd rows in alternating sequence within a single frame period, enabling background light suppression without the delay of processing two complete frames. This dynamic processing approach directly improves frame rate while maintaining suppression reliability.

Inventive Principle:

Principle #15Dynamics

3Measurement precision

If conventional TOF scheme with two frames is used, then depth measurement accuracy is improved, but system cost and area increase

Engineering Contradiction:

Improvedepth measurement accuracyVSAvoidsystem cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent merges the requirements of two-frame processing into a single-frame architecture, reducing the number of memory components needed. This merging approach maintains depth measurement accuracy through background light suppression while reducing system area and manufacturing cost.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent changes the operational parameters by processing even and odd rows in an alternating single-frame scheme rather than using two complete frames. This parameter change maintains measurement precision while reducing the hardware resources required, thereby lowering system cost.

Inventive Principle:

Principle #35Parameter changes

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 approach reduces memory requirements, enhances frame rate, and improves system performance by calculating depth information using one frame data, thereby reducing costs and increasing operational speed.

Implementation Method 1

An image sensor includes a plurality of pixels that convert photons in a spectral band into electrons

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentUS11467264B2Apparatus for measuring depth with pseudo 4-tap pixel structure

Publication Date: 2022.10.11 SOLIDVUE INC

AI summary

Provided is an apparatus for measuring a depth with a pseudo 4-tap pixel structure, the apparatus including a delta sigma circuit configured to calculate, through a delta sigma operation, a delta value of a first angle corresponding to a first row line of a pixel array for measuring a depth of an object and calculate, through a delta sigma operation, a delta value of a third angle corresponding to a second row line of the pixel array, a memory configured to store the calculated delta value of the first angle corresponding to the first row line, and an arithmetic logic unit (ALU) configured to compute depth information corresponding to the first row line by using the stored delta value of the first angle corresponding to the first row line and the calculated delta value of the third angle corresponding to the second row line.