Conductive Layer Dissipating Charge in Electromechanical Display
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Solution Overview
Problem
Charge buildup within the cavity of electromechanical systems (EMS) devices, such as MEMS, can lead to electrostatic forces that cause light modulators to stick or become permanently inoperable, due to their proximity to substrate surfaces and the large adjacent surface areas.
Innovation Solution
Incorporating a transparent or light-absorbing electrically conductive layer in contact with the fluid within the cavity, which dissipates charge migration and reduces electrostatic forces by being at the same electrical potential as the light modulators, and using conductive spacers to maintain electrical connection while allowing substrate deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light modulator is disposed close to a substrate surface with large adjacent surface area, then the light modulator can be effectively positioned within the cavity, but charge buildup produces strong electrostatic forces that cause the light modulator to stick or become permanently inoperable
Solution Approach 1:
A conductive layer is introduced as an intermediary between the light modulator and the substrate surface. This conductive layer dissipates charge that migrates through the fluid, preventing charge buildup and the resulting electrostatic forces from affecting the light modulator. The conductive layer acts as a charge sink that protects the light modulator while allowing it to maintain its close positioning to the substrate.
Solution Approach 2:
The electrical potential parameter of the conductive layer is controlled to match the electrical potential of the light modulator. By maintaining the same electrical potential, the conductive layer minimizes electrostatic attraction forces while still providing charge dissipation functionality. This parameter matching reduces the harmful electrostatic effects without compromising the light modulator's positioning or operation.
2Reliability
If a conductive layer is added to dissipate charge, then electrostatic forces are reduced and light modulator reliability improves, but the device structure becomes more complex
Solution Approach 1:
The conductive layer serves multiple functions simultaneously: it dissipates charge to prevent electrostatic buildup, provides a structural substrate for fluid contact, and can be integrated with existing device layers. By combining charge dissipation with structural functionality, the invention reduces overall device complexity compared to adding a separate dedicated charge dissipation mechanism.
Solution Approach 2:
The conductive layer is merged with the substrate structure or existing device layers, combining the charge dissipation function with the structural support function. This integration approach avoids adding separate components and minimizes the increase in device complexity while achieving the reliability improvement.
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
The conductive layer effectively reduces electrostatic forces, preventing light modulators from sticking or becoming damaged, thereby ensuring correct operation and extending the lifespan of the display elements.
Implementation Method 1
A transparent electrically conductive layer is disposed on the second planar surface and in contact with the fluid to dissipate charge migrating through the fluid
Implementation Method 2
A light-absorbing electrically conductive layer is disposed on the second planar surface and in contact with the fluid to dissipate charge migrating through the fluid
Implementation Method 3
A light-absorbing electrically conductive layer is disposed on the second planar surface and in contact with the fluid to dissipate charge migrating through the fluid
Implementation Method 4
a conductive spacer can be disposed within the cavity and in electrical communication with the light modulator and the transparent electrically conductive layer
Implementation Method 5
A plurality of additional conductive spacers are positioned within the display region... substantially prevents the first and second substrates from deforming within the display region
Data Source
AI summary
This disclosure provides systems, methods and apparatus for dissipating charge buildup within a display element with a conductive layer. The conductive layer is maintained in electrical contact with a fluid within the display element. The fluid, in turn, remains in contact with light modulators within the display elements. Any charge buildup that may be caused by the filling of the fluid during fabrication of the display device, or during operation of the light modulators can be dissipated by the conductive layer. Thus, by dissipating the charge buildup, the conductive layer reduces or eliminates electrostatic forces due to the charge buildup that may affect the operability of the light modulators. The display can include conductive spacers in an active display region of the display and a spacer-free region that allows the substrates to deform while retaining an electrical connection between the conductive layer and the spacers in the active display region.