Projector Cooling System Isolates Optical Unit From Dust

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Solution Overview

Problem

Conventional image projectors face the challenge of dust adhering to optical devices in the projection optical unit, which degrades image quality, while also requiring effective cooling of heat-generating components.

Innovation Solution

The design incorporates a configuration where the first intake duct is located on the base part facing the light modulator, allowing direct airflow to the heat sink, and the exhaust vent is positioned to prevent outside air from entering the projection optical unit, reducing dust adherence and increasing airflow volume without increasing fan revolutions or power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If air is circulated through the projection optical unit for cooling, then cooling efficiency is improved, but dust adheres to optical devices degrading image quality

Engineering Contradiction:
Improvecooling efficiencyVSAvoiddust adherence
Core Design Contradiction:
TemperatureVSObject-affected harmful factors

Solution Approach 1:

The patent divides the air circulation system into separate pathways: a first air circulation pathway for cooling the projection optical unit, and a second air circulation pathway for cooling other components. This segmentation allows the cooling air for the projection optical unit to be isolated from dust-containing environments, preventing dust adherence to optical devices while maintaining effective cooling.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary structure (a cover or barrier) that separates the projection optical unit from the general internal environment of the projector. This intermediary prevents dust-laden air from reaching the optical devices while still allowing heat to be dissipated through the dedicated cooling pathway.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Temperature

If fan revolutions are increased to improve cooling, then cooling efficiency is improved, but noise and power consumption increase

Engineering Contradiction:
Improvecooling efficiencyVSAvoidpower consumption
Core Design Contradiction:
TemperatureVSUse of energy by moving object

Solution Approach 1:

The patent employs a variable speed fan that dynamically adjusts its rotation speed based on the thermal conditions of the projection optical unit. This allows the system to maintain optimal cooling efficiency while minimizing power consumption and noise by operating the fan at the lowest necessary speed rather than continuously at high revolutions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements a feedback control system that monitors the temperature of the projection optical unit and adjusts fan speed accordingly. When cooling demand is low, the fan operates at lower speeds reducing power consumption and noise; when cooling demand increases, the fan speed increases to maintain optimal temperature, thus resolving the contradiction between cooling efficiency and power consumption.

Inventive Principle:
Principle #23Feedback

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 dust from adhering to optical devices, maintains image quality, and enhances cooling efficiency without increasing noise or power consumption.

Implementation Method 1

the light modulator 10 includes a heat sink 13 as a radiating device that radiates heat that the image generating device gives off

Methodology Applied
Scientific EffectHeat radiation: Thermal Radiation

Implementation Method 2

The intake blower 191 takes outside air from the surface facing the intake duct 84 via the intake duct 84... The air taken by the intake blower 191 flows to the vertical duct 192... After moving through the horizontal duct 93, the air flows in the light source unit 60

Methodology Applied
Scientific EffectForced convection: Forced Convection

Data Source

PatentEP2816406B1Image projector comprising a cooling system
Publication Date: 2018.02.28 RICOH CO LTD
  • EP2816406B1 patent drawingFigure 1
  • EP2816406B1 patent drawingFigure 2
  • EP2816406B1 patent drawingFigure 3

AI summary

An image projector (1) that air-cools an image generating device and a light source and can prevent dust from being adhered to optical devices in a projection optical unit is provided. The image projector (1) includes a projection optical unit (30, 40) that projects an image including a gap, and a case (59, 53) that contains the projection optical unit (30, 40). The case (59, 53) includes an exhaust vent (85) that is located on a predetermined surface of the case (59, 53) at a position facing a first fan (86), a first intake duct (92) provided on a surface of the case (59, 53) so as to face a second fan (91), and a second intake duct (84) provided on a surface different than the surface where the first intake duct (92) is provided. Air that flows from the first intake duct (92) toward the exhaust vent (85) is prevented from flowing in the gap, and air that flows from the second intake duct (84) toward the exhaust vent (85) flows in the gap.