Image Sensor Dust Removal Timing Control

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Solution Overview

Problem

Existing image pickup apparatuses face challenges in simultaneously performing live view display and dust removal functions without compromising image quality, as dust removal mechanisms often introduce noise into the live view image due to high voltage application and electrical grounding variations.

Innovation Solution

An image pickup apparatus that includes an image sensor, an optical member, a vibration unit, and a control unit, where the control unit vibrates the optical member during non-readout periods between charge accumulation and readout cycles, allowing for real-time live view display without noise interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the piezoelectric element is activated to vibrate the optical member for dust removal, then dust removal effect is improved, but noise is superimposed on the LV image

Engineering Contradiction:

Improvedust removal effectVSAvoidnoise superimposition on LV image

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies periodic action by controlling the piezoelectric element to vibrate only during specific time intervals (between readout periods) rather than continuously. The control unit activates the vibration unit during periods when the image sensor is accumulating charge but not reading out, creating a periodic duty cycle that eliminates noise from the LV image while maintaining dust removal effectiveness over time.

Inventive Principle:

Principle #19Periodic action

2Productivity

If the LV display function and dust removal function are performed simultaneously, then real-time image confirmation is maintained, but noise from high voltage application degrades image quality

Engineering Contradiction:

Improvereal-time image confirmationVSAvoidnoise from boosting transformer

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent implements periodic action by synchronizing the dust removal vibration with the image sensor's charge accumulation and readout cycles. The vibration occurs during charge accumulation periods when no readout is happening, thereby maintaining continuous LV display functionality while eliminating noise interference during critical readout phases.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent applies preliminary action by performing dust removal vibrations during the charge accumulation phase before the readout phase begins. This timing strategy ensures that dust is removed in advance of the sensitive readout period, preventing noise superimposition on the LV image while maintaining real-time display capability.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the dust removal execution time is extended to improve dust removal performance, then dust removal effect is enhanced, but LV image updating is stopped for longer periods

Engineering Contradiction:

Improvedust removal performanceVSAvoidLV image update interruption time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent resolves this contradiction by utilizing the periodic charge accumulation and readout cycles of the image sensor. By confining vibrations to the charge accumulation period (which naturally occurs between readout periods), the system can extend dust removal duration without interrupting LV image updating, as the vibration periods are filled within the otherwise idle accumulation intervals.

Inventive Principle:

Principle #19Periodic action

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

Enables real-time, high-quality live view image display while effectively removing dust from the optical member, preventing noise superimposition and ensuring continuous image capturing functionality.

Implementation Method 1

a vibration unit configured to vibrate the optical member

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

an image sensor configured to photoelectrically convert an optical image of a subject to accumulate electric charge

Methodology Applied

Scientific EffectPhotoelectric conversion: Photoelectric Effect

Data Source

PatentUS10244172B2Image pickup apparatus and imaging method therefor

Publication Date: 2019.03.26 CANON KK

AI summary

An image pickup apparatus includes an image sensor configured to photoelectrically convert an optical image of a subject to accumulate electric charge, an optical member located on a subject side of the image sensor, a vibration unit configured to vibrate the optical member, a display unit configured to display a moving image based on a captured image signal output from the image sensor, and a control unit configured to perform drive control of the image sensor, the vibration unit, and the display unit, wherein, in a case where the optical member is vibrated while the moving image is displayed, the control unit causes the vibration unit to vibrate the optical member in a time between two readout periods for reading out electric charge accumulated in the image sensor and not to vibrate the optical member in the readout periods.