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A PDLC film or glass also known as "smart glass" is a transparent film or glass with liquid PDLC crystal inside which, when electrical field is generated, can act as an optical shutter. Unlike the traditional LCD shutter it
1) doesn't block light but scatters it
2) it makes no use of polarizers so the light transmittance efficiency is about 85% over about 45% for LCD.
It is also very cheap and can be cut into any shape or size and as far as I know can be thermoformed to make curved goggles.
Why isn't it used for 3d stereoscopic shutter glasses you might ask? Probably because it
1) needs 60V AC to operate in normal operation mode (electric field on/off) over the 3.3-5V DC for LCDs
2) because ordinary PWM AC voltage fading speed of the material isn't fast enough
3) but most probably because 3d TVs died around the time several companies were developing PDLC shutter glasses and when it comes to 3D cinemas those use a different technology without shutter glasses so there hasn't been a market need to develop them.
For a shutter glasses usage PDLC needs to switch from on state to off state or off stage to on stage in 0.008 seconds, or 8 ms, but with ordinary electrical field switching the max speed it achieves appears to be 40 ms, which is darn close.
Luckily there's a different method to switch the state of the PDLC crystal discussed in this paper:
https://www.researchgate.net/publication/3254347_Reduction_of_the_switching_time_of_polymer-dispersed_liquid_crystal_using_field_oriented_addressing
By the method described there PDLC switching times can reach the level needed for 3d shutter glasses and unlike 50% light loss from LCD shutter glasses they will preserve 82% of the unpolarized light. And it might not even need 60V AC and work at lower and/or DC current.
...but the wording in the above paper is a bit vague. If anyone understands what "two finger electrodes" means and how they work in this context and if they could work with a transparent conductor such as ITO film instead of an aluminum reflector used for PDLC screens I can give this idea a try.
I already have some spare PDLC films and a lab PSU with oscilloscope, just let me know if you are interested and let me know what experiments to perform.
PS. I'm interested in implementing PDLC shutter glasses in my VR system over the existing LCD shutter glasses to improve brightness and have no interest in making profit on the glasses but you might find some real business potential in helping get a working low power but high performance PDLC shutter glasses prototype made and use the gathered info in your own product. For example shutter glasses are still used by NVidia and home cinema DLP projectors. I don't mind.
1) doesn't block light but scatters it
2) it makes no use of polarizers so the light transmittance efficiency is about 85% over about 45% for LCD.
It is also very cheap and can be cut into any shape or size and as far as I know can be thermoformed to make curved goggles.
Why isn't it used for 3d stereoscopic shutter glasses you might ask? Probably because it
1) needs 60V AC to operate in normal operation mode (electric field on/off) over the 3.3-5V DC for LCDs
2) because ordinary PWM AC voltage fading speed of the material isn't fast enough
3) but most probably because 3d TVs died around the time several companies were developing PDLC shutter glasses and when it comes to 3D cinemas those use a different technology without shutter glasses so there hasn't been a market need to develop them.
For a shutter glasses usage PDLC needs to switch from on state to off state or off stage to on stage in 0.008 seconds, or 8 ms, but with ordinary electrical field switching the max speed it achieves appears to be 40 ms, which is darn close.
Luckily there's a different method to switch the state of the PDLC crystal discussed in this paper:
https://www.researchgate.net/publication/3254347_Reduction_of_the_switching_time_of_polymer-dispersed_liquid_crystal_using_field_oriented_addressing
By the method described there PDLC switching times can reach the level needed for 3d shutter glasses and unlike 50% light loss from LCD shutter glasses they will preserve 82% of the unpolarized light. And it might not even need 60V AC and work at lower and/or DC current.
...but the wording in the above paper is a bit vague. If anyone understands what "two finger electrodes" means and how they work in this context and if they could work with a transparent conductor such as ITO film instead of an aluminum reflector used for PDLC screens I can give this idea a try.
Using a 3 electrode pixel electrode (Fig. 1) it is possible to generate a horizontal and a vertical electric field. One transmissive indium tin oxide (ITO) electrode is on the cover glass and two Al finger electrodes (electrode A and B) are on the back plane of the display. The ITO electrode has a fixed potential.
When electrode A and B have the same potential different from the potential of the ITO electrode there will be a vertical electric field across the cell gap of the display. When the difference in potential between electrode A and the ITO electrode and between electrode B and the ITO electrode are the same in magnitude but with opposite sign, the electric field in the cell gap between electrode A and B will have a predominant horizontal component. In this way it is possible to switch between a horizontal and a vertical electric field in the cell gap between the finger electrodes.
I already have some spare PDLC films and a lab PSU with oscilloscope, just let me know if you are interested and let me know what experiments to perform.
PS. I'm interested in implementing PDLC shutter glasses in my VR system over the existing LCD shutter glasses to improve brightness and have no interest in making profit on the glasses but you might find some real business potential in helping get a working low power but high performance PDLC shutter glasses prototype made and use the gathered info in your own product. For example shutter glasses are still used by NVidia and home cinema DLP projectors. I don't mind.