EVF Optical Path Split Prism for Line-of-Sight Detection

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Solution Overview

Problem

Existing imaging apparatuses with electronic viewfinders (EVFs) and line-of-sight detection functions lack a suitable optical arrangement that prevents dust ingress and maintains operability, particularly in the relative arrangement of operation members and built-in components.

Innovation Solution

The imaging apparatus incorporates an optical path split prism unit and a line-of-sight detection mechanism, including an optical path split prism, infrared LEDs, and a proximity detection unit, which are integrated into the EVF structure to minimize visibility and maintain operability while enabling line-of-sight detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If an optical path split mirror is used to enable line-of-sight detection through the EVF, then line-of-sight detection function is achieved, but dust in the finder may affect visibility and operability

Engineering Contradiction:
Improveline-of-sight detection functionVSAvoiddust ingress affecting visibility
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The optical path is divided into separate channels: a first optical path for the display image and a second optical path for line-of-sight detection. The optical path split prism separates these paths, allowing the line-of-sight detection sensor to receive light through a dedicated path while the display remains unaffected by dust in either path.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The optical path split prism acts as an intermediary element that redirects light from the display panel to the line-of-sight detection sensor through a separate optical path. This mediator enables the detection function without compromising the main display path, isolating the two functions from each other's harmful effects.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the line-of-sight detection sensor is positioned on the common optical path, then line-of-sight detection is enabled, but it may interfere with the display image visibility

Engineering Contradiction:
Improveline-of-sight detection capabilityVSAvoiddisplay image visibility
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The optical path is segmented into distinct first and second paths. The first path carries the display image to the user's eye, while the second path carries light from the display panel to the line-of-sight detection sensor. This segmentation ensures that the sensor does not intercept display image light, maintaining full visibility.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The optical path split prism redirects light from the first optical path into the second optical path at a different spatial dimension or angle. This dimensional change allows the line-of-sight detection to occur without blocking or interfering with the primary display image path.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Volume of moving object

If operation members and built-in members are arranged in a compact configuration, then device size is reduced, but operability may decrease due to spatial constraints

Engineering Contradiction:
Improvedevice sizeVSAvoidoperability
Core Design Contradiction:
Volume of moving objectVSEase of operation

Solution Approach 1:

The eyepiece portion is positioned in a direction substantially perpendicular to the optical axis of the EVF, utilizing spatial arrangement in another dimension. This perpendicular arrangement allows operation members to be positioned without interfering with the optical path, maintaining operability while achieving compact integration.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The optical path split prism has an asymmetric configuration where the first and second optical paths are arranged at different angles and positions. This asymmetric layout optimizes the spatial relationship between the display path and detection path, allowing compact arrangement while maintaining clear separation of functions and preserving operability.

Inventive Principle:
Principle #4Asymmetry

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 effectively prevents a decrease in operability by reducing crosstalk and maintaining functionality, ensuring clear visibility and accurate line-of-sight detection without compromising the overall performance of the imaging apparatus.

Implementation Method 1

an optical path split unit configured to reflect light from the display panel away and to guide external light to the sensor

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

The EVF structure includes infrared LEDs and a proximity detection unit

Methodology Applied
Scientific EffectLight Emitting Diode: Light Emitting Diode

Data Source

PatentEP4054169B1Imaging device, electronic apparatus, and finder unit
Publication Date: 2025.10.01 CANON KK
  • EP4054169B1 patent drawingFigure 1A~1B
  • EP4054169B1 patent drawingFigure 2
  • EP4054169B1 patent drawingFigure 3

AI summary

An imaging apparatus including a first sensor configured to image an optical subject image incident via a first lens unit includes a display panel, an eyepiece portion, a second sensor configured to image an eye of a user viewing the display panel by looking into the eyepiece portion, the second sensor being different from the first sensor, an optical path split unit configured to guide light from the display panel to outside the imaging apparatus and to guide external light to the second sensor, and a second lens unit disposed between the optical path split unit and the eyepiece portion, wherein the second sensor is disposed at a different side from a side where a grip region of the imaging apparatus is disposed with respect to an optical axis of the second lens unit.