News Release: The former Hitachi Displays

March, 29 2006

IPS LCD Panels for Mobile terminals Developed with Photo Sensor Formed on Glass
- Allowing automated, optimum luminance on mobile terminals -

Hitachi Displays, Ltd. (President: Kazuhiro Mori) recently developed a new technology to mount a photo sensor that measures ambient luminance on the glass of a TFT LCD frame. This technology enables the photo sensor to measure ambient luminance and automatically feed data to the backlight circuit on the LCD module to set the optimum luminance. The luminance is set to low levels for indoors, typically the condition under which mobile terminals are used for long periods, resulting in power savings.

Images on the displays conventionally used for mobile phones, car navigation systems and other mobile terminals may blur due to a sudden change in ambient luminance, when for example viewers move from indoors to outdoors or enter a tunnel on a freeway. This is caused by the way in which the human eye adapts to surrounding conditions, and for this reason, mobile terminals have to increase display luminance in bright conditions and reduce it in the dark.

We have developed a technology to form a photo sensor on the glass of the TFT LCD panel frame to provide a display adaptive to changes in conditions. Specifically, a photo sensor and a circuit to convert signals from the sensor to duration-modulated pulses are formed on the glass substrate of the TFT LCD using low-temperature polysilicon technology. The signal conversion circuit formed on the glass substrate can reduce noise and measure ambient luminance more steadily.

Hitachi Displays will demonstrate this new technology at the Display 2006 show to be held at Tokyo Big Sight from April 19, 2006. Sample shipment is scheduled for the latter half of this fiscal year.

[Main Specifications]3.9" IPS TFT LCD

Size of Display 9.9cm (3.9")
Number of Display Pixels 320 (H) × 480 (V)
Number of Colors 260,000
Viewing angle Over 170° horizontally and vertically
Luminance 100 to 300cd/m2
Contrast Ratio 500 :1

What is IPS technology?

IPS technology is a horizontally charging LCD technology that functions differently to conventional TFT LCDs. It was unveiled in 1995, and has been in practical use since 1996, evolving to Super-IPS, to Advanced-Super IPS and finally to IPS-Pro. Liquid crystal molecules rotate parallel to the TFT substrate when a charge is applied horizontally. This simple movement of molecules produces superior performance in terms of viewing angle, color reproductivity and response speed to halftones.