1. Light Engine Design and Manufacturing Development in Projection System
Sung-Nan Chen, et al., SID 08 DIGEST 70.4
Speaker: Yu-Cheng Lai(賴佑禎)
Advisors: Prof. Han-Ping D. Shieh (謝漢萍教授)
Prof Yi-Pai Huang (黃乙白教授)
Institute of Electro-Optical Engineering,
National Chiao Tung University, Hsinchu, Taiwan
Aug. 4, 2008 1

2. Outline UHP type projection engine LED illumination design
Laser optical engine
Summary
This the outline
First I introduce the traditional UHP type lamp in relative to various integrator design in illumination
Then talk about LED type, focus on lighting efficiency, and laser illumination design

3. Introduction 3 kinds of projection 3LCD three-panel structure
single-panel structure
DLP
DLP
LCOS
LCOS
There are 3 kinds of method to project image, DLP 3LCD LCOS
Now I introduce how to generate image by these systems.
In DLP system, light output from the lamp is divides into RGB colors by dichroic mirror, then each color is emitted to the respective DMD component, which can modulate each color, then combine these light by projection lens and generate the image.
In 3LCD system, light is also divided into RGB by dichroic mirror, then each color passes through the LCD panel to modulate and combine together. Finally it will create the image.
In LCOS system, the work principle is similar to the 3LCD system.
When mentioning the single-panel structure, the working principle is the same with three-panel system.
The different is use one micro display and color wheel in the optical engine.

4. UHP(Ultra high performance) type lamp projection engine
Integrator
integrator
Light pipe integrator
Fly-eyes integrator
Lenticular structure
In projection system the imager is rectangular shape , so to transfer circular light source to rectangular shape, and making the uniform illumination , the light integrator is necessary.
In DLP system, almost all illumination design with light pipe structure.
light pipe made by 4 reflective mirrors, which light reflected by nature TIR. Refer to the fig.
The Fly-eyes device, light is divided into multiple sections by the 1st element, and then overlapped onto imager by the 2nd element.
As a result of multiple overlap of divided original light source, light becomes more uniform and collimated, as fig.
Lenticular structure is similar to Fli-eyes. It contains 2 elements, 1st multi-cylinder lens element expend light source in only one direction.
Then the 2nd element works in the orthogonal direction. Therefore light becomes more uniform and collimated.
The illumination area of light pipe is smaller than the others, but the collimated effect is better

5. LED illumination design
Integrator is before color mixing
Integrator is after color mixing
Lens array structure
14mm diameter collimator lens
11mm diameter collimator lens
In LED section, they focus on the lighting efficiency
With LED’s long lifetime and vivid color, it has been used widely in daily necessary and facilities
LED projection consists of color mixing module, lighting integrator, and projection lens.
When designing color mixing system, two types need to be taken into consideration. One is the color mixing module before light integrator, another is after integrator.
The structure (a) has better chance to more compact light engine because it doesn’t need another lens
Another choice is to use fly-eyes integrator as shown in the right side. With proper array curvature, it is more useful to design a smaller size system and mitigate color uniformity problem.
In order to achieve the smaller size and increase the system efficiency, LED collimator lens play an important role.
The collimator lens expects to be lager in order to collect effective wider angle and large emitting area.
This figure shows in the same condition, different diameter causes different divergent angle. The smaller collimator will lead to larger divergent angle
The larger collimator will lead to smaller divergent angle

6. Laser optical engine Laser’s advantages 1. Laser’s single wavelength
wider color gamut
2. Laser’s pure polarization
higher contrast ratio
Laser’s drawback
Heat problem
LCOS
DLP
Laser is a light source which is monochromatic and coherent.
Because the laser’s single wavelength, it can have wide color gamut display to over 130% of NTSC.
The second advantage is the pure polarized light, so laser projection can achieve higher contrast ratio.
Its drawback is the heat problem
The bottom picture shows optical engine. There are two approaches in color mixing 3 panel projection system. as left picture shows , one is to specify three colors match to each imager directly. The other is the integrator collect 3 colors laser first then separate to respective colors in illumination with two dichronic mirrors as right fig. shown.
The advantages:
1.wider color gamut
2.higher contrast ratio

7. Summary Light source UHP lamp LED Laser Advantage High brightness
1. Longer lifetime
(~60000 hrs)
2. Wide color gamut
3. small size of the optical engine
1. Wider color gamut
2. Higher contrast ratio
Drawback
Shorter lifetime
(~10000 hrs)
Collimated issue
Heat problem
Optical engine
DLP, 3LCD,LCOS
Finally, I give a brief summary.

8. Novel Single Panel Projection Systems
Yong-Jing Wang, et al., SID 08 DIGEST 70.3
Speaker: Yu-Cheng Lai(賴佑禎)
Advisors: Prof. Han-Ping D. Shieh (謝漢萍教授)
Prof Yi-Pai Huang (黃乙白教授)
Institute of Electro-Optical Engineering,
National Chiao Tung University, Hsinchu, Taiwan
Aug. 4, 2008 1

9. Outline Introduction Novel projection system Summary
It is my outline. First is the introduction, I’ll talk about some projection systems
Then mention some the novel projection system about function and optical design
Finally , it is summary.

10. Introduction Three-panel structure DLP 3LCD LCOS
Three–panel structure: expensive and bulky
single-panel structure
DLP
LCOS
Because of three-panel structure uses color combination optics and three micro display, therefore it is expensive and bulky.
The single-panel structure almost uses color wheel to produce color. So it has color artifact problems.
In order to improve these problems which is expensive and optical engine.
This paper shows a novel single panel projection system.
Color wheel method :color artifact problems

11. Novel projection system
Single panel projection structure(SP2)
In order to improve these problems which is expensive and optical engine.
This paper shows a novel single panel projection system. System schema shows in the left side.
It comprise a micro-display panel that displays RGB colors in spatially separated segment
There are three dichroic mirrors in the system
These mirrors are used to tilt the different color beams with different angel and reflect the beams onto the projection lens, so that colors are combined together to form a full color image on a screen. i.e. the dichroic mirrors selectively tilt the different color to form the image.
The projection lens layout shows in the right side
(The projection lens was designed with a 0.72 inch diagonal panel and this 8-piece design was designed at the F/#2.2 )
System schema
Projection lens layout

12. Novel projection system
Illumination system
Because the illumination system need to emit light in side by side RGB color segments, and keeping the projection lens size.
It could be the full-light pipe based system.
The system consist of the dichroic prism and light pipe.
Dichroic prism can split white color into RGB, and the light pipe is used to control uniformity and cone angle.
Dichroic prism: split color
Light pipe: control uniformity and cone angle

13. Novel projection system
Advantages
1.Compactness
Color combiner X-Cube
Novel system
3-panel system
2.Low cost
3.Compability
Save the backplane size about 30%
The yield is higher
This page, I’ll mention some advantage of the novel system.
1.compactness
In the three-panel structure, the color combiner system makes the system bulky
In this novel system doesn’t need it.
Therefore this system is compact and ideal for portable projector.
2.Low cost
Due to the elimination of periphery area overall backplane size for a this system is smaller than the size for 3-panels. as shown in fig.
It saves the backplane size about 30%. And it also reduce the cost peripheral electronics and package cost.
Besides, the response time requirement for the system is less compares with traditional other panel. Therefore the cell gap can become thicker than LC panel, so the yield will be higher.
3.Compatibility
This system could be compatible with DLP, LCD, LCOS technologies.
And the illumination system also could be compatible with lamp, LED, and laser source.
Therefore, it is suitable for the microdisplay panel tech and promising for compact pico projectors.

14. Summary
This novel single panel projection system utilizes angular color method to generate image.
This system has some advantages such as:
1.compact system
2.high color efficiency
3.low cost simple optical system
prototype specification
Resolution
WVGA(1080X600)
Panel
0.72 inch
Lamp
50W Ujoy
Lumen
200
Projection lens
F/#2.2
Here, I give a short summary …….
And the system spec. shown as table

15. Conclusion Comparison Type 3LCD LCOS DLP SP2 system Merit
1.No color artifact
2.Simple optical engine
1.High brightness
2.Low panel cost
3.High optical efficiency
1.High optical efficiency
2.Fast response time
1.Very simple
optical system
2.High optical
efficiency
3.Low cost
Drawback
1.Low contrast ratio
2.Less optical efficiency
1.High optical component cost
4.Low yield
1.Complex process
2.The copyright
The manufacture of the dichronic mirror
Light source
UHP lamp
LED
Laser

16. Thanks for your kind attention

17. Dichronic mirror
A mirrors with significantly different reflection or transmission properties at different wavelengths.
It can reflects a specific region of light and transmits other regions. Separates the three primary colors of blue, green and red from white light.
A mirrors with significantly different reflection or transmission properties at different wavelengths.
It can reflects a specific region of light and transmits other regions. Separates the three primary colors of blue, green and red from white light.

18. Laser optical engine Heat problem
Laser is a light source which is monochromatic and coherent.
The laser can have wide color gamut display to over 130% of NTSC. And laser’s collimated characteristic which has higher coupling efficiency.
Based on the Etendue calculation it is almost linear via different imager size as show in fig.
The coupling efficiency of small imager is the same as bigger one.
The bottom picture shows optical engine. There are two approaches in color mixing 3 panel projection system. as left picture shows , one is to specify three colors match to each imager directly. The other is the integrator collect 3 colors laser first then separate to respective colors in illumination with two dichronic mirrors as right fig. shown.
How to cool the laser optical engine is a issue no matter DLP or LCOS system.
The laser output is sensitive to temperature variation.
Laser wattage trend via ambient temperature as shown in fig.
From the fig. we could find the output power will be reduced if temperature on laser chip is too high.
One method to take heat away is shown here. The heat sink attach to laser and heat pipe connect s to a fan, so the heat of laser chip can be taken away.
To reduce the thermal in-between ambient and laser chip, other new method is combine heat sink and laser base. The heat pipes pass through laser base directly shown as fig. this method can improve over 30% thermal efficiency comparing to original one.

19. Ujoy lamp the short arc is ideal for use with a microdisplay
Almost all current projection systems rely on UHP lamp technology because of its unique combination of properties
The Ujoy 50 W projection lamp technology combines the advantages of UHP lamps with lower power consumption and a compact design. High-collection efficiency, a good colour balancing and long life
the short arc is ideal for use with a microdisplay
An etendue of 10mm^2 sr requires a light source as small as 1mm. High brightness from a small emitting volume points to a short arc lamp

20. Etendue
Etendue:
:source area
:cone angle
:refractive index

21. Lumen budget

22. Novel projection system
The challenges
1.Resolution
2.Color convergence
This fig. shows the MTF of green channel of the projection lens
The MTF for all three color channels are greater than 30% at 60 lp/mm.
Obviously, the resolution itself is not a problem for the system.
The convergence issue cause by the distortion.
The convergence of RGB picture of each field point are shown in the right fig.
For the edge points, there are some pixels mismatch between 3color pictures.
The problem could be reduced by optimizing the optical system, however they use
Electronic method to reduce mismatch to keep the cost and size.
After processing, the result is shown here.

23. DMD DMD:Digital Micromirror Device
The DMD is comprised of millions of micromirroes
The display principle : the DMD reflect the light by using these tiny micromirror.
These micormirrors can reflect light to different angle, and project the image.