Display system, display device and display method
US-2024201540-A1 · Jun 20, 2024 · US
Tunable rejection liquid crystal filter
US2016178946A1 · US · A1
| Field | Value |
|---|---|
| Publication number | US-2016178946-A1 |
| Application number | US-201314909566-A |
| Country | US |
| Kind code | A1 |
| Filing date | Aug 6, 2013 |
| Priority date | Aug 6, 2013 |
| Publication date | Jun 23, 2016 |
| Grant date | — |
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Abstract
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Apparatus and method for tuning a liquid crystal filter to the wavelength of incoming electromagnetic radiation (such as visible light) by exploiting the AC error signal produced by the filter when a tuning error is present.
First claim
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1 . Apparatus for tuning a liquid crystal filter powered by an alternating driving voltage, to reject incident light comprising: means for deriving an electrical signal from the variation in transmission of the filter associated with the alternating driving voltage wherein the sign of the electrical signal is dependent on whether the wavelength of the incident light is greater, or less than, the rejection wavelength of the filter and means for deriving a control signal for the alternating driving voltage from the electrical signal. 2 . The apparatus of claim 1 , wherein the magnitude of the control signal is dependent on the magnitude of the electrical signal. 3 . The apparatus of claim 1 , wherein the alternating driving voltage takes the form of a square wave. 4 . The apparatus of claim 1 , arranged so that the alternating driving voltage is increased if the control signal is positive and decreased if the control signal is negative. 5 . The apparatus of claim 1 , arranged so that the alternating driving voltage is decreased if the control signal is positive and increased if the control signal is negative. 6 . The apparatus of claim 1 in which the birefringence of the filter increases with applied voltage. 7 . The apparatus of claim 1 in which the birefringence of the filter decreases with applied voltage. 8 . Use of apparatus according to claim 1 for the protection against laser damage. 9 . A method of tuning a liquid crystal filter powered by an alternating driving voltage, to reject incident light, comprising the steps of: deriving an electrical signal from the variation in transmission of the filter associated with the alternating driving voltage wherein the sign of the electrical signal is dependent on whether the wavelength of the incident light is greater, or less than, the rejection wavelength of the filter and increasing or decreasing the alternating driving voltage according to the sign of electrical signal so derived.
Assignees
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Classifications
- G02F1/13306Primary
Circuit arrangements or driving methods for the control of single liquid crystal cells (G02F1/132, G02F1/133382 take precedence) · CPC title
- G02F1/13318Primary
Circuits comprising a photodetector · CPC title
wavelength filtering · CPC title
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Frequently asked questions
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- What does patent US2016178946A1 cover?
- Apparatus and method for tuning a liquid crystal filter to the wavelength of incoming electromagnetic radiation (such as visible light) by exploiting the AC error signal produced by the filter when a tuning error is present.
- Who is the assignee on this patent?
- Secr Defence
- What technology area does this patent fall under?
- Primary CPC classification G02F1/13306. Mapped technology areas include Physics.
- When was this patent published?
- Publication date Thu Jun 23 2016 00:00:00 GMT+0000 (Coordinated Universal Time) (A1). Legal status and post-grant events are not shown on this page.
- What related patents are in patentsdb?
- We list 8 related publications on this page (citations in our corpus or others sharing the same primary CPC).