Film-type patterned retarder
Film-type Patterned Retarder (abbreviated: FPR, LG Product Marketing: CINEMA 3D ) is the name for a technology of stereoscopic, digital image reproduction based on circular polarization , which is used in the 3D displays of televisions and monitors from the South Korean company LG Electronics is used. The first television set equipped with CINEMA 3D technology was launched worldwide in May 2011. Previously it was only available in a few countries.
definition
The origin of the term CINEMA 3D is derived from 3D films shown in cinemas. The polarization technology used in CINEMA 3D has been widespread there for some time. This technology is also known as film-type pattern retarder (FPR) or as "passive 3D" and was developed by LG Display since 2009, a division within the LG Group.
FPR method
With the FPR method, the TV display shows the image for the left and right eye at the same time. The two images are interlaced line by line by a film for circular polarization, at least with today's devices. In order to be able to separate the two images again in order to achieve the stereo impression, the viewer wears circularly polarized glasses which should only let through the intended image components and general light from the environment for the left and right eye, while the opposite Image is removed.
CINEMA 3D should be characterized above all by the flicker-free viewing of the image content, a disruptive effect that is often described in the case of the shutter technology, which is also used to display stereoscopic content. The viewing angle in the horizontal direction is relatively large. In the vertical direction, however, it is rather narrow. Turning the viewer's head has no effect on the images themselves because of the circular polarization. However, if the head is tilted significantly, the person no longer recognizes the images as they match and the stereo effect is lost.
FPR technology can be used to equip screen types such as plasma , LED-LCD, LCD , OLED or even mobile phones, as the image signals are separated using a film applied to the respective display.
technology
description
In order to display a stereoscopic, three-dimensional image or a film, two images are displayed on the same screen, which are separated from one another by a circular polarization arranged in the opposite direction . The viewer wears glasses that are also equipped with polarization filters. Light that was polarized to the left is hidden by the right-handed filter and vice versa. This makes it possible to display two different images at the same time and make them visible separately for each eye. Provided that the projected images are appropriately recorded, the viewer then gets a spatial impression. CINEMA 3D can be used with televisions, monitors, laptops, smartphones and projectors.
Compared to conventional technology
The possibility of seeing two different images, which provide a spatial impression for the viewer, has been realized for some time by so-called shutter technology. Two different images are projected individually at short intervals. The viewer wears glasses with lockable glasses controlled with the help of electrical impulses. Alternately, when looking at the screen, the left or right eye is covered and thus only the left or right image intended for the relevant eye is made visible. Due to the sluggishness of the optical perception of the human eye, the viewer should then create a spatial image impression. Compared to the polarization-based technology of the CINEMA 3D, interferences in image perception are repeatedly criticized with the shutter technology:
- Blinking effect . Since other light sources also emit light in the corresponding frequencies, the shutter technology can lead to annoying, headache-inducing and eye-tiring flashing effects. These are excluded with the CINEMA 3D technology due to the use of polarization technology.
- Image overlap . Despite the use of highly complex technology, users of the shutter technology repeatedly describe a disruption of the spatial impression due to image overlapping. This effect occurs when one image is visible to the wrong eye for a fraction of a second. This negative effect does not occur with CINEMA 3D because of fundamentally different technical requirements.
- Viewing angle . With the shutter technology, the three-dimensional effect only occurs within a defined angle at which the viewer is positioned to the image axis. This angle is about 80 degrees. A viewer who looks at a screen from the side, i.e. who is outside this angle, cannot perceive any spatial image impression. With CINEMA 3D this angle is much larger at around 180 degrees.
- Luminance . The use of special glasses with conventional shutter technology limits the incidence of light. Therefore the luminance is about 65 cd / m². CINEMA 3D, on the other hand, enables a light intensity of around 170 cd / m². As a result, the image appears richer in contrast and enables a more true-to-color reproduction.
- Motion blur . Since images are displayed with a frequency of 60 Hz using conventional shutter technology, rapid movements within the film content can lead to blurring. Since CINEMA 3D displays images at a frequency of 240 Hz, motion blurring is excluded.
- Glasses . Since the 3D glasses at CINEMA 3D consist exclusively of polarization filters, there is no need for a technically complex design as with the shutter technology. Since there is no need for a power supply or a signal transmission between the projection device and glasses for the purpose of synchronizing the image content and visibility, the CINEMA 3D glasses are not only much lighter (about half), but also cheaper to manufacture (about a Tenth).
- Screen resolution . This is where the only disadvantage of the process compared to the shutter technology becomes apparent. Since the pixel lines are alternately polarized for the right and left eye, the devices only achieve 540 lines (half FullHD) per eye when displaying 3D content. This can, depending on the viewing distance, significantly deteriorate the image quality.