Privacy filters, sometimes also known as light control film (LCF) such the 3M Vikuiti A-LCF and Optical Filters K-LCF consist of many thin louvers that function like a vertical window blind restricting the path of light through the filter. The display is clear and un-distorted to the user directly within the viewing axis, but to either side the image is blackened and un-readable.
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ere are a number of applications for displays where privacy for the viewer is required such as an outdoor privacy screen in an ATM, medical kiosk, in-flight entertainment screens and polling booths. Other applications are for contrast enhancement and light control such as pedestrian crossing units and head down avionics where the re-directed light limits the near field canopy reflections.
Privacy filters are offered either as standard plain or non-glare matte hard coated polycarbonate filters typically 0.5mm (0.021″) thick precision cut to final size, laminated into glass or plastic for thickness and extra ruggedisation, or integrated with a touch screen. Lamination with glass or plastic adds the options to have anti-reflection and anti-finger print coatings, chemically toughened glass and EMI shielding.
3M Vikuiti A-LCF is the established product replacing previous LCF-P and AG-LCF variations. Its continuous micro-replicated black embedded louvers is very high quality, but expensive:
| Description | 3M Vikuiti Advanced light control film |
| Louver angle | sheets are 0° ±2°, typical bias to avoid display source interference +5° minimum |
| View angle | 60° ±4° (30° either side of center) |
| Maximum sheet size | 431.8 x 431.8mm (17 x 17″) |
| Thickness of film | 0.53mm (0.021″) Other thickness supplied by optical index match lamination |
| Finish | Standard gloss (ABR0) or matt non-glare hard coating (ABR2) |
| Transmittance | 70% |
| Operating Temperature | -40 to +75°C (limitations of the lamination) |
The K-LCF is a high value alternative to the 3M product. The privacy control is the same and the filters construction is similar to previous LCF-P types.
| Description | Optical Filters K-LCF |
| Louver angle | + 15° ±3° standard bias to avoid display source interference +5° minimum |
| View angle | 60° ±4° (30° either side of center) |
| Stock sheet size | 17″ diagonal 270 x 340mm (louver parallel +15° to the 270mm side) Larger sizes up to 1200 x 760mm (47 x 30″) to special order |
| Thickness of film | 0.53mm (0.021″) Other thickness supplied by optical index match lamination |
| Finish | Standard plain or matt non-glare |
| Transmittance | 75% |
| Operating Temperature | -40 to +75°C (limitations of the lamination) |
Alternative technologies
Blur film technology dispersed the incident light at particular angles and transmitting it at all other angles. The appearance therefore, changes from translucent to transparent depending on the angle from which it is viewed. This method was less effective when the distance of the filter to the display source was reduced and never become widely adopted. Production ended several years ago and it is no-longer available