Date: May 20, 2009 

By Winstar Display 

 

ISTN-LCD - A New Alternative Solution for 

High Contrast/Wide View Angle Display 

 

Nowadays, the demand of high contrast ratio for electronic devices is always be an 

important issue.    Relevant technology aims at the development to improved contrast 

for monochrome LCD display is to offer DFSTN (Double-Film-Compensated STN) 

or OLED display.     

 

However, the cost for these two solutions is much higher compared to ISTN-LCD 

technology.    Due to the properties of the ISTN technology of high contrast and with 

wide viewing angles and high brightness, it is very suitable for automotive instrument, 

hand held applications, automotive instrument, test and measurement equipment and 

other industrial products. 

 

ISTN-LCD technology offers a real alternative to mono LCD for applications that 

require exceptional contrast ratios and wider viewing angles. 

 

 

 

 

 

 

 

 

ISTN-LCD Display with Red LED Backlight 

 

 

What is ISTN-LCD Technology? 

ISTN (Improved Super Twisted Nematic) incorporates a special dichroic dye into 

normal STN liquid crystal.  The ISTN technology adds a compound called the 

dichroic dye into the liquid crystal and which has the feature of anti-isotropic to 

absorb the visible light coefficient.  Since the amount of the extra compound of 

dichroic dye was very small, amounting under 1%, it has been called as Guest and the 

original liquid crystal called as Host.  Therefore, the ISTN technology also is known 

as Guest-Host liquid crystal display (GH-LCD).     

 

 

Technical theory of ISTN: 

The ISTN technology is adding a rod-like dichroic dye into the normal STN liquid 

crystal.    Just like the drawings shown in the below picture I, the external electric 

field changed, the dichroic dye direction will be changed as normal liquid crystal.     

 

While without any voltage apply to the ISTN-LCD, the incident light direction 

through the polarizer is parallel to the dichroic dye, therefore, the light would be 

absorb by the dichroic dye molecules which is shown as the below drawing (a).     

 

When voltage has been applied to the ISTN-LCD, the incident light direction through 

the polarizer is vertical to the dichroic dye, therefore, the most portion of the light 

would pass through the dichroic dye molecule which is shown as the below drawing 

(b).    The absorption difference by the incident light pass through the polarizer is 

called as dichroic ratio.    It’s obviously to see the difference of the wavelength v.s 

absorption for the above mentioned (a) and (b) drawings of without and with voltage 

apply to the ISTN-LCD.    Through the above theory of the ISTN-LCD mode, we can 

take the advantage of this feature to get a wide viewing angle and high penetration of 

high contrast display.     

 

 

Polarizer

(b)

(a)

Absorption 

700

600

500

400

Wavelength(nm)

: Dye molecule

: LC molecule

ISTN-LCD

Polarizer

(b) Apply Voltage(V=Vop )

(a) Without Voltage(Vop= 0)

Incident Light(White)

Incident light(White)

 

 

 

 

 

Features of ISTN-LCD: 

A very important characteristic of ISTN-LCD is the dichroic ratio of ISTN-LCD 

varies from the proportion of doped dye molecule and doped concentration.    Below 

picture II is an example absorption spectrum for using different ratio of dye molecule 

as reference. 

 

Picture I 

 

-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

300

400

500

600

700

800

900

4wt%

VA

3wt%

8wt%

20wt%

Wavelength(nm)

   

 
 

 

Main Features: 

1. Very dark background display 

2. High contrast and brightness 

3. Wide viewing angle 

By using the advantages of different color and chroma of dichroic dye along with the 

different LED backlights and special polymer film as a second cell to compensate 

light dispersion resulting in a thinner display and improved viewing properties such as 

wide viewing angles and high brightness.    Below drawings are the spectrum 

examples by using dichroic dye and LED backlight as reference.   

Picture II

 

=

+

B /L   e m is s io n  

s p e c tr u m

B /L   e m is s io n  

s p e c tr u m

=

+

d is p la y   s p e c tr u m

n o n - d is p la y  

s p e c tr u m ( B a c k g r o u n d )

D y e   a b s o r p tio n  

s p e c tr u m

( w /o   v o lta g e )

D y e  a b s o rp tio n  

s p e c tru m
( A p p ly   v o lta g e )

 

 

The best performance of ISTN-LCD display is with RED, Amber, and Green LEDs. 

       

 

 

ISTN-LCD Display with Amber LED Backlight

 

 

 

 

 

Hopefully with this article, it would be a great help for the readers to have basic 

information about ISTN-LCD Technology.    If you need further information, please 

contact with us.    Thank you. 

 

Winstar Display Co. Ltd. 

No. 163 Chung-Chung Road, Taichung City, Taiwan, R.O.C. 

Tel: 886-4-24262208 

Fax: 886-4-24262207 

sales@winstar.com.tw

 

www.winstar.com.tw 

ISTN-LCD Display with Green LED Backlight