Photoaddressed Cholesteric Liquid Crystal Display Without Drive Electronics

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Solution Overview

Problem

Conventional liquid crystal display (LCD) technologies are costly and bulky due to the need for complex electronics and multiple electrical connections, making them unsuitable for applications like point-of-sale signs and body-worn displays where simplicity, low cost, and low power consumption are essential.

Innovation Solution

A photoaddressed cholesteric reflective display that uses ultraviolet or visible light to shift the reflective wavelength of chiral nematic liquid crystals, eliminating the need for drive and control electronics by incorporating photosensitive chiral additives that change the helical twisting power in response to light, allowing for high-resolution image creation without patterned electrodes or complex circuitry.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional LCD technology is used with drive chips and control circuitry, then electrical control and display functionality are achieved, but cost, weight, and bulkiness increase significantly

Engineering Contradiction:

Improvedisplay control capabilityVSAvoiddisplay system weight

Core Design Contradiction:

Ease of operationVSWeight of stationary object

Solution Approach 1:

The patent extracts and removes the drive chips and control circuitry from the display system, replacing them with a photoconductive layer that enables optical addressing. This eliminates the heavy electronic components while maintaining display control capability through light-based addressing of the liquid crystal material.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the electrical control system (drive chips, control circuitry, electrical interconnects) with an optical control system using a photoconductive layer. This substitution eliminates the need for complex electrical wiring and heavy electronics, reducing weight and bulkiness while maintaining display functionality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If multiple electrical interconnects are used to connect drive chips to display electrodes, then high-resolution image addressing is achieved, but manufacturing complexity and cost increase

Engineering Contradiction:

Improveimage resolutionVSAvoidelectrical interconnect complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent removes the complex electrical interconnect system and drive chips, replacing them with a photoconductive layer that enables direct optical addressing of the display electrodes. This simplifies the device structure while maintaining the ability to address individual pixels for high-resolution imaging.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The photoconductive layer acts as an intermediary between the light source and the liquid crystal material. It converts optical signals into electrical signals locally at each pixel, enabling high-resolution addressing without requiring complex electrical interconnects or centralized drive chips.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If drive electronics are removed to simplify the display system, then cost and bulkiness are reduced, but the ability to change images is lost

Engineering Contradiction:

Improvedisplay system simplicityVSAvoidimage change capability

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The photoconductive layer serves as a mediator that enables image changing capability without requiring drive electronics. By converting optical addressing signals into local electrical signals, it allows the display to be rewritten and updated while maintaining system simplicity and low cost.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The display system performs self-addressing through the photoconductive layer, which converts optical signals directly at each pixel location. This eliminates the need for external drive electronics while maintaining the ability to change images, as the system uses light to address and update the display content.

Inventive Principle:

Principle #25Self-service

4Device complexity

If photoconductive layer is introduced to enable optical addressing, then drive electronics are eliminated, but additional manufacturing steps are required

Engineering Contradiction:

Improveelectronic component countVSAvoidmanufacturing process steps

Core Design Contradiction:

Device complexityVSEase of manufacture

Solution Approach 1:

The patent uses a composite structure combining a photoconductive layer with the liquid crystal display layers. This integration allows the photoconductive material to be incorporated into the existing display manufacturing process, adding functionality while minimizing additional manufacturing complexity.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS8329058B2Chiral nematic photo displays

Publication Date: 2012.12.11 KENT DISPLAYS INC

AI summary

A photodisplay device in which an optically addressed image can be viewed indefinitely, erased and readdressed with a new image is disclosed. Optically responsive reversible photochiral materials are incorporated into a bistable cholesteric liquid crystal in an electrooptic display cell. A high resolution image exposed on the cell is fixed by a low voltage pulse to unpatterned electrodes and can be, at a later time, erased with a high voltage pulse.