vickybat
I am the night...I am...
Okay guys I had planned a compilation of 3d technology used in current displays, how its differs from cinema 3d and its negative effects on us. After doing extensive reading from various sources, I finally decided to put everything into place.
It all happened when me, our forum member cilus and my brother went to Orissa’s biggest fair known as baliyatra and saw a demo of both active 3d and passive 3d. I will extensively discuss those elements in detail. It’s a lengthy article so have patience and read.
Before starting, let me provide a few prerequisites such as IPS panel technology and how 3d works so that it becomes easier to read further and comprehend. I decided to include ips because its becoming the panel of choice over traditional VA and TN panels. Even Samsung has gone far enough to introduce SUPER –PLS which is based on ips and Samsung claims it to be an evolution of ips.
IPS – Now we all know that IPS stands for in plane switching. It was developed by hitachi limited in 1996 to cope with poor viewing angles and colour reproduction problems of TN panels. The difference here is that in IPS panels, the liquid crystal molecules move parallel to a plane rather than perpendicular.When this happens , the liquid crystal shapes are same i.e horizontal and parallel to the plane. So it appears same in any viewing angle.
This actually changes the light scattering matrix in the molecules resulting in wide viewing angles and better colour reproduction.
The following screenshot will help visualize better:
*i.imgur.com/r18KM.jpg
Current adopters of IPS panels are hitachi,Panasonic and lg. Panasonic is actually one of the leading manufacturer of ips panels followed by lg.
Okay now since we are done with an important panel type, lets move on to 3d….
Stereoscopic 3D- Stereoscopy is an illusion created by the brain in seeing depth. This illusion incurs when two images from an object converge at the same focal point in our eyes. The brain then mixes both images to create a 3d image of that object.
When we see distant objects , they appear flat. That’s because rays of light coming from that object are parallel. The farther it is the ray coming to the left eye is parallel to the ray coming to the right eye. As it comes closer and closer, the rays of light seem to converge. Our eyes shift focus to adjust and we see more detail of that object including depth or in other words, how far the object is from us. If our eyes converge quite a bit, the object is much closer to us.
This very phenomenon is used in 3d displays and devices. By showing two images, in a different location, we can trick the brain to think that the object has depth. But the convergence and focal points won’t match with that of a real object. So what happens here is we use special glasses to block light from 1st image and allow light from the 2nd image and vice-versa at a fast pace. These two images of the object must have different orientations.
Doing so fools the brain to think that the light from the object in the screen converge at a point which is different from focal point because the focus is on the tv screen thus giving the illusion of depth and we can view the object in all 3 dimensions. Check the following illustration for a brief idea:
*i.imgur.com/g6LuP.jpg
Now we venture into 3d’s real implementations in modern world. I will skip the anaglyph red and blue glass technology as its obsolete. Still it can be viewed in the above pictorial representation.
There are two methods that are used currently to view 3d content on displays and cinemas. They are active 3d and passive 3d. Though cinema’s use passive 3d or REAL D 3D only, the use of passive glasses have moved on to commercial displays intended for personal use. Remember that the older anaglyphic glasses were also passive but current ones are different because they use polarization technique which were not used in earlier passive glasses. Now lets venture a bit deeper shall we :
Active 3d- Active 3d is the most common and widely used 3d in commercial displays and promoted by brands like Sony, Panasonic and Samsung. They get the name active due to the glasses they support. Basically the glasses here are termed as active and not the panel. Active 3d glasses are nothing but liquid crystal displays acting as the lens of the glasses. These have a shutter mechanism that blocks light source making them opaque in one instance and transparent in the other. Active glasses have their own energy source in form of a battery from which the name active comes in.
The display running 3d content has two images with a slightly different orientation with respect to each other. Lets consider the left image as img1 and right image as img 2. Light from img1 falls on the left lens and right lens. But at this instance , the right lens turns black or simply turns opaque. Therefore only the left eye sees img1. Similarly for img 2, the left lens turns opaque and only the right eye sees the respective image. This switching technique happens at a very fast rate at around 480 times a second and the brain merges the two images by a process called binocular fusion. This creates an illusion of depth depending on the extremity of the images known as interoccular difference which is directly proportional to binocular fusion.
Now the data has to be synced between the tv screen and the glasses so that proper switching take place. This is done by infrared or Bluetooth connectivity between the glasses and the display.
Active 3d delivers 3d content in the highest resolution supported by the native display. If you are watching 1080p 3d , then the end resolution will also stay the same without any loss of clarity. But active 3d has problems of its own and the most important one is “flickering”. Though the shutter mechanism in the glasses switch at a fast rate, most of the times the wearer experiences screen flicker of alternate black and white lines. This can be annoying and in the same time have adverse effects on the brain and its perception capability. Long hours of active 3d viewing will bring health problems.
Besides this , the shutter glasses are very expensive and if a big family is viewing an active 3d content in the same living room, it becomes an expensive affair to arrange enough active shutter glasses for everybody. The pic below shows an active shutter glass:
*i.imgur.com/SymBm.png
Passive3d – Passive 3d has been around for quite sometime. In cinema’s or movie theaters who provide 3d content use this type of 3d. Passive 3d for commercial displays is developed by LG. Here, all the 3d technology is given to the display rather than the glasses (in simple layman’s terms). The main objective of passive 3d is to do away with the general problems that active 3d faces which is flickering.
Passive 3d’s are completely flicker free and provide a neutral 3d viewing experience. So how does it work? We will discuss that in the following:
Passive 3d employs a property of light known as polarization which is a property of a wave that defines the orientation of oscillations. Two types of polarization are employed in passive 3d which are linear polarization and circular polarization. The latter is used now in commercial displays.
Linear polarization- In linear polarization, the light wave, after polarization will have two orthogonal (perpendicular) components in phase. Therefore the resultant vector tip will trace a path similar to a single line. Hence its called as linear polarization.
*i.imgur.com/vxffW.png
Circular Polarization- In circular polarization, the light wave, after polarization will have two orthogonal (perpendicular) components out of phase by 90 degrees. Therefore the resultant vector tip will trace a circle in the plane. Hence its called as circular polarization.
*i.imgur.com/m5tbc.png
Conversion of linear polarization to circular polarization : Linearly polarized light is converted to circularly polarized light by slowing one component of the field. Effectively, the light is given a twist. This is achieved by using a material that transmits light at different speeds depending on its polarity. In the diagram below, we can see a linearly polarized light wave (simple blue wave entering at left) oriented at 45 degrees to the system. Projected onto the vertical and horizontal planes are the vertical and horizontal components of that wave (equal and in phase). When that wave passes through the material, the vertical component is slowed down so that it is out of phase with the horizontal component. When it is a quarter wavelength slower, the resulting wave is helical. To an observer receiving the circularly polarized light, the electric field of that light will appear to rotate rather than just bob up and down. Notice how the dark red horizontal component passes through without change but how the dark blue vertical component is held back. The diagram is a very very simplified version.
*i.imgur.com/lpWZx.jpg
Now these two techniques are employed onto the 3d display and the passive glassesof a passive 3d setup. We will discuss circular polarization technique for 3d as linear ones are obsolete now
Here’s how:
Working:- Passive displays have a film over its panel known as FPR or film patterned retarder. This consists of several strips which perfectly align with the vertical lines of the display. Each strip of the FPR is actually a polarizer which circularly polarizes the light ( from linear to circular). Check below to see an illustration of passive glasses:
*i.imgur.com/7Ttm0.jpg
Unlike active 3d, passive 3d displays send both the images superimposed at the same time. However, the vertical resolution of each frame is split into alternating lines. So, the first line will display the first line of the left image, the second line will show the first line of the second image, the third line will show the second line of the left image etc. So the left lines are left circularly polarized and right lines are right circularly polarized. Now both these polarized lights falls on the user’s glasses at once.
The passive glasses have a pair of analyzing filters a.k.a circular polarizers mounted in reverse of opposite handedness. Light that is left circularly polarized is blocked by the right analyzer and vice versa. The analyzing filters are made up of a combination of a quarter wave plate(QWP) and a linear polarizing filter. The QWP converts circular polarization into linear polarization whereas the linear polarizing filter will allow resultant wave to pass depending on its angle and handedness (left or right). The illustration below shows the working of a left handedness analyzer.
*i.imgur.com/3vFbY.png
Thus each eye gets one image at an instance but the brain superimposes them into a resulting 3d image. The concept is similar to active stereoscopy albeit with a different technique employed.
But passive 3d incorporating FPR’S have a small demerit. A passive TV halves the vertical resolution to 540 lines because they are alternated with the lines from both images.
So each eye is seeing a 1920 X 540 picture. However, because both eyes are seeing a different 540 line picture, the sum is 1080 lines (the brain is said to interpret the combined image as a 1080 line picture). Thus we can safely say that So each eye is seeing a 1920 X 540 picture. However, because both eyes are seeing a different image which the brain combines, passive tv’s are fullhd. The much brighter side is that they completely do away with the flickering issues of active 3d panels.
Okay guys that’s more like it. There are other 3d techs like parallex barrier and lenticular displays which I have purposely left out as they are not so mainstream now. Planning to add them in the very near future. Please post your valuable comments for further improvements on this article.
It all happened when me, our forum member cilus and my brother went to Orissa’s biggest fair known as baliyatra and saw a demo of both active 3d and passive 3d. I will extensively discuss those elements in detail. It’s a lengthy article so have patience and read.
Before starting, let me provide a few prerequisites such as IPS panel technology and how 3d works so that it becomes easier to read further and comprehend. I decided to include ips because its becoming the panel of choice over traditional VA and TN panels. Even Samsung has gone far enough to introduce SUPER –PLS which is based on ips and Samsung claims it to be an evolution of ips.
IPS – Now we all know that IPS stands for in plane switching. It was developed by hitachi limited in 1996 to cope with poor viewing angles and colour reproduction problems of TN panels. The difference here is that in IPS panels, the liquid crystal molecules move parallel to a plane rather than perpendicular.When this happens , the liquid crystal shapes are same i.e horizontal and parallel to the plane. So it appears same in any viewing angle.
This actually changes the light scattering matrix in the molecules resulting in wide viewing angles and better colour reproduction.
The following screenshot will help visualize better:
*i.imgur.com/r18KM.jpg
Current adopters of IPS panels are hitachi,Panasonic and lg. Panasonic is actually one of the leading manufacturer of ips panels followed by lg.
Okay now since we are done with an important panel type, lets move on to 3d….
Stereoscopic 3D- Stereoscopy is an illusion created by the brain in seeing depth. This illusion incurs when two images from an object converge at the same focal point in our eyes. The brain then mixes both images to create a 3d image of that object.
When we see distant objects , they appear flat. That’s because rays of light coming from that object are parallel. The farther it is the ray coming to the left eye is parallel to the ray coming to the right eye. As it comes closer and closer, the rays of light seem to converge. Our eyes shift focus to adjust and we see more detail of that object including depth or in other words, how far the object is from us. If our eyes converge quite a bit, the object is much closer to us.
This very phenomenon is used in 3d displays and devices. By showing two images, in a different location, we can trick the brain to think that the object has depth. But the convergence and focal points won’t match with that of a real object. So what happens here is we use special glasses to block light from 1st image and allow light from the 2nd image and vice-versa at a fast pace. These two images of the object must have different orientations.
Doing so fools the brain to think that the light from the object in the screen converge at a point which is different from focal point because the focus is on the tv screen thus giving the illusion of depth and we can view the object in all 3 dimensions. Check the following illustration for a brief idea:
*i.imgur.com/g6LuP.jpg
Now we venture into 3d’s real implementations in modern world. I will skip the anaglyph red and blue glass technology as its obsolete. Still it can be viewed in the above pictorial representation.
There are two methods that are used currently to view 3d content on displays and cinemas. They are active 3d and passive 3d. Though cinema’s use passive 3d or REAL D 3D only, the use of passive glasses have moved on to commercial displays intended for personal use. Remember that the older anaglyphic glasses were also passive but current ones are different because they use polarization technique which were not used in earlier passive glasses. Now lets venture a bit deeper shall we :
Active 3d- Active 3d is the most common and widely used 3d in commercial displays and promoted by brands like Sony, Panasonic and Samsung. They get the name active due to the glasses they support. Basically the glasses here are termed as active and not the panel. Active 3d glasses are nothing but liquid crystal displays acting as the lens of the glasses. These have a shutter mechanism that blocks light source making them opaque in one instance and transparent in the other. Active glasses have their own energy source in form of a battery from which the name active comes in.
The display running 3d content has two images with a slightly different orientation with respect to each other. Lets consider the left image as img1 and right image as img 2. Light from img1 falls on the left lens and right lens. But at this instance , the right lens turns black or simply turns opaque. Therefore only the left eye sees img1. Similarly for img 2, the left lens turns opaque and only the right eye sees the respective image. This switching technique happens at a very fast rate at around 480 times a second and the brain merges the two images by a process called binocular fusion. This creates an illusion of depth depending on the extremity of the images known as interoccular difference which is directly proportional to binocular fusion.
Now the data has to be synced between the tv screen and the glasses so that proper switching take place. This is done by infrared or Bluetooth connectivity between the glasses and the display.
Active 3d delivers 3d content in the highest resolution supported by the native display. If you are watching 1080p 3d , then the end resolution will also stay the same without any loss of clarity. But active 3d has problems of its own and the most important one is “flickering”. Though the shutter mechanism in the glasses switch at a fast rate, most of the times the wearer experiences screen flicker of alternate black and white lines. This can be annoying and in the same time have adverse effects on the brain and its perception capability. Long hours of active 3d viewing will bring health problems.
Besides this , the shutter glasses are very expensive and if a big family is viewing an active 3d content in the same living room, it becomes an expensive affair to arrange enough active shutter glasses for everybody. The pic below shows an active shutter glass:
*i.imgur.com/SymBm.png
Passive3d – Passive 3d has been around for quite sometime. In cinema’s or movie theaters who provide 3d content use this type of 3d. Passive 3d for commercial displays is developed by LG. Here, all the 3d technology is given to the display rather than the glasses (in simple layman’s terms). The main objective of passive 3d is to do away with the general problems that active 3d faces which is flickering.
Passive 3d’s are completely flicker free and provide a neutral 3d viewing experience. So how does it work? We will discuss that in the following:
Passive 3d employs a property of light known as polarization which is a property of a wave that defines the orientation of oscillations. Two types of polarization are employed in passive 3d which are linear polarization and circular polarization. The latter is used now in commercial displays.
Linear polarization- In linear polarization, the light wave, after polarization will have two orthogonal (perpendicular) components in phase. Therefore the resultant vector tip will trace a path similar to a single line. Hence its called as linear polarization.
*i.imgur.com/vxffW.png
Circular Polarization- In circular polarization, the light wave, after polarization will have two orthogonal (perpendicular) components out of phase by 90 degrees. Therefore the resultant vector tip will trace a circle in the plane. Hence its called as circular polarization.
*i.imgur.com/m5tbc.png
Conversion of linear polarization to circular polarization : Linearly polarized light is converted to circularly polarized light by slowing one component of the field. Effectively, the light is given a twist. This is achieved by using a material that transmits light at different speeds depending on its polarity. In the diagram below, we can see a linearly polarized light wave (simple blue wave entering at left) oriented at 45 degrees to the system. Projected onto the vertical and horizontal planes are the vertical and horizontal components of that wave (equal and in phase). When that wave passes through the material, the vertical component is slowed down so that it is out of phase with the horizontal component. When it is a quarter wavelength slower, the resulting wave is helical. To an observer receiving the circularly polarized light, the electric field of that light will appear to rotate rather than just bob up and down. Notice how the dark red horizontal component passes through without change but how the dark blue vertical component is held back. The diagram is a very very simplified version.
*i.imgur.com/lpWZx.jpg
Now these two techniques are employed onto the 3d display and the passive glassesof a passive 3d setup. We will discuss circular polarization technique for 3d as linear ones are obsolete now
Here’s how:
Working:- Passive displays have a film over its panel known as FPR or film patterned retarder. This consists of several strips which perfectly align with the vertical lines of the display. Each strip of the FPR is actually a polarizer which circularly polarizes the light ( from linear to circular). Check below to see an illustration of passive glasses:
*i.imgur.com/7Ttm0.jpg
Unlike active 3d, passive 3d displays send both the images superimposed at the same time. However, the vertical resolution of each frame is split into alternating lines. So, the first line will display the first line of the left image, the second line will show the first line of the second image, the third line will show the second line of the left image etc. So the left lines are left circularly polarized and right lines are right circularly polarized. Now both these polarized lights falls on the user’s glasses at once.
The passive glasses have a pair of analyzing filters a.k.a circular polarizers mounted in reverse of opposite handedness. Light that is left circularly polarized is blocked by the right analyzer and vice versa. The analyzing filters are made up of a combination of a quarter wave plate(QWP) and a linear polarizing filter. The QWP converts circular polarization into linear polarization whereas the linear polarizing filter will allow resultant wave to pass depending on its angle and handedness (left or right). The illustration below shows the working of a left handedness analyzer.
*i.imgur.com/3vFbY.png
Thus each eye gets one image at an instance but the brain superimposes them into a resulting 3d image. The concept is similar to active stereoscopy albeit with a different technique employed.
But passive 3d incorporating FPR’S have a small demerit. A passive TV halves the vertical resolution to 540 lines because they are alternated with the lines from both images.
So each eye is seeing a 1920 X 540 picture. However, because both eyes are seeing a different 540 line picture, the sum is 1080 lines (the brain is said to interpret the combined image as a 1080 line picture). Thus we can safely say that So each eye is seeing a 1920 X 540 picture. However, because both eyes are seeing a different image which the brain combines, passive tv’s are fullhd. The much brighter side is that they completely do away with the flickering issues of active 3d panels.
Okay guys that’s more like it. There are other 3d techs like parallex barrier and lenticular displays which I have purposely left out as they are not so mainstream now. Planning to add them in the very near future. Please post your valuable comments for further improvements on this article.
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