AMVA Ultrahigh Contrast Ratio & Ultra-wide Viewing Angle Technology
In conventional MVA technology, the major culprit of light leakage in the dark state comes from protrusion. However, the new generation of AMVA developed by AUO utilizes the latest PSA (Polymer-Stabilized Alignment) technology (Fig. 1) to remove protrusions on the CF substrate in conventional MVA technology and thereby significantly reduces light leakage in the dark state. Compared to MVA technology, AMVA technology achieves significant improvements in cell transmittance and continues to make progress in backlight film, polarizer, and color filter technology. The technology delivers a more stereoscopic and sharper image display, and achieves ultra high contrast ratios (Fig. 2 and 3).
The core of this new technology lies in its alignment film formed on the liquid crystal panel. The fabrication process, occurs when a small amount of monomers are added to the liquid crystal molecules. Once the liquid crystal molecules and monomers have been injected, a voltage is then applied to the cell which gives the liquid crystal molecules near the polyimide area a pre-tilt angle. An appropriate amount of exposure to UV then fixes the pre-tilt angle and completes both the polymer stabilization and the alignment of the liquid crystals.
The pixel design of AMVA uses eight domains (Fig. 1). The color washout issue under large viewing angles in the VA mode (Fig. 5) has been effectively addressed, leading to better viewing angle performance (Δu'v'< 0.02).
|Fig.1 Schematic comparison of new generation AMVA and conventional MVA technologies.|
|Fig.2 Comparison of optical properties in AMVA and conventional MVA technologies.|
Fig.3 Comparison of horizontal viewing angles in AMVA and conventional MVA technologies.
By utilizing new pixel and optical film designs and optimized color filter photo resists, AMVA offers a contrast ratio of 16000:1, as well as wide viewing angles of up to 89 degrees in all four directions (Fig.4 and 5).
|Fig.4 Comparison of contrast in new generation AMVA and conventional MVA technologies.|
|Fig.5 Comparison of low color washout inside angle images using AMVA and conventional MVA technologies.|
Advantages of AUO AMVA Technology
- High contrast (static contrast as high as 16,000: 1;No.1 in the world)
- High cell transmittance (cell transmittance increased by more than 30% when compared to conventional designs)
- Wide viewing angle (large viewing angle with low color washout; Δu'v'< 0.02 meets multiple views requirements)
- Fast response time (alignment technology provides uniform alignment, increasing liquid crystal response speed up to MPRT < 5ms)
- Low power consumption (higher cell transmittance lowers number of LEDs used; backlight module offers better power-savings)
- Suitable for development by fabs of any generation (already validated in G8.5 line)
AMVA-mobile technology is designed specifically for mobile devices. The technology mixes the liquid crystal materials with reactive monomer that will polymerize upon PI by UV light. After a special cell fabrication process that involves applying voltages and UV light irradiation, the reactive monomer will polymerize to form a polymer layer on the polyemid. This polymer functions like micro-scale protrusion without reducing the aperture ratio and is able to provide fast response time for the liquid crystal to achieve its pre-tilt angle.
AMVA-mobile process flow
LC alignment Comparison of AMVA-m and traditional MVA technology
Advantages of AUO AMVA-mobile Technology
- Non-protrusion process
‧Less CF process steps
- High brightness
‧No main slit, no protrusion
- High contrast ratio
‧High A.R, no protrusion
‧Brighter L255, Darker L0
- Fast response time
‧All pixel area with pre-tilt angle
Compare with traditional MVA Model：
- Higher Transmittance (AR > 15%)
- Contrast ratio (>2000 with Line POL)
- Faster Response time (< 22 ms)
AMVA-car technology applies protrusion-less structure and specific pixel structure to get high contrast ratio and fast response time. The technology mixes the liquid crystal materials with reactive monomer that will polymerize upon PI by UV light. After a special cell fabrication process that involves applying voltages and UV light irradiation, the reactive monomer will polymerize to form a polymer layer on the polyemid (Fig.1). This polymer functions like micro-scale protrusion without reducing the aperture ratio and is able to provide fast response time. Therefore the technology can achieve stable liquid crystal alignment at four domains after process.
The conventional MVA technology has light leakage due to protrusion which is LC alignment element (Fig.2). In addition, MVA has slow response time because of its propagation method (Fig.3). AMVA-car technology features fast response time because it makes a little pre-tilt angle upon PI.
|Fig.2-1 Dark state at MVA||Fig.2-2 Dark state at AMVA-car|
Fig.3 Shows the LC response methods of AMVA-car and Conventional MVA
Advantages of AUO AMVA-car Technology
- Non-protrusion process.
- Less CF process steps
- Cost down
- High A.R. (Aperture Ratio)
- High aperture ratio, no protrusion
- Brighter at full brightness (L255), Darker at zero brightness (L0)
- All display areas with pre-tilt angle
- First in industry to realize the concept of polymer-stabilized alignment, which is a high-transmittance alignment technology
- AMVA-car can achieve a high contrast ratio of about 2500:1
- AMVA-car can achieve faster response time at low temperature. The response time at -20。C is 220ms