Light Input Display Edge Detection Circuit

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Solution Overview

Problem

Conventional display devices with light input functions face challenges in accurately determining whether an object has contacted the screen and calculating its coordinate position, especially in varying ambient light conditions, due to limitations in edge detection and binary image processing.

Innovation Solution

The implementation of edge detection circuits, inter-frame difference processing circuits, and modulation circuits to form edge and difference images, which enhance contact determination and coordinate calculation accuracy by identifying spatial changes and temporal variations in the imaged image.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If binary monochrome gradation imaging is used, then device complexity is reduced, but measurement precision of reflected light deteriorates

Engineering Contradiction:

Improveimage processing complexityVSAvoidreflected light determination accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent applies dynamics by making the image processing method adaptive to different ambient light conditions. The system dynamically switches between binary monochrome processing (for dark environments) and multi-gradation processing (for light environments), allowing the processing complexity and precision to vary according to environmental conditions rather than being fixed

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of image gradation from fixed binary to variable (binary or multi-gradation based on ambient light). By detecting ambient light levels and adjusting the image processing mode accordingly, the system optimizes the balance between processing complexity and measurement precision for reflected light determination

Inventive Principle:

Principle #35Parameter changes

2Reliability

If shadow detection method is used in dark environment, then contact detection capability is improved, but measurement precision of object position deteriorates

Engineering Contradiction:

Improvecontact detection capabilityVSAvoidobject position accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The system dynamically adjusts the detection method based on ambient light conditions. In dark environments, it uses shadow detection to ensure contact detection reliability, while in light environments, it switches to reflected light detection to improve position measurement precision, thus adapting the method to environmental constraints

Inventive Principle:

Principle #15Dynamics

3Speed

If simple binary image processing is used, then processing speed is improved, but measurement precision of light intensity deteriorates

Engineering Contradiction:

Improveprocessing speedVSAvoidlight intensity accuracy

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The system dynamically selects the processing method based on ambient light conditions. When ambient light is dark, it uses simple binary processing to maintain high processing speed. When ambient light is sufficient, it employs multi-gradation processing to achieve higher light intensity measurement precision, thus dynamically balancing speed and precision requirements

Inventive Principle:

Principle #15Dynamics

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 significantly improves the accuracy of contact determination and coordinate calculation, enabling reliable input in both dark and light environments by utilizing edge and difference images effectively.

Implementation Method 1

optical sensor elements provided in respective pixels; an amount of charge of each capacitor is changed in response to a change of an amount of received light in each photodiode

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentUS7800594B2Display device including function to input information from screen by light

Publication Date: 2010.09.21 MAGNOLIA WHITE CORP

AI summary

In order to enhance accuracy of determination as to whether an object has contacted a screen and to enhance accuracy of calculation of a coordinate position of the object, edges of an imaged image are detected by an edge detection circuit 76, and by using the edges, it is determined by a contact determination circuit 77 whether or not the object has contacted the screen. Moreover, in order to appropriately control sensitivity of optical sensors in response to external light, by a calibration circuit 93, a drive condition of the optical sensors is changed based on output values of the optical sensors, which are varied in response to the external light.