Methods for driving a transflective liquid crystal display device

• US 8,913,219 B2
• Filed: 03/15/2013
• Issued: 12/16/2014
• Est. Priority Date: 06/30/2005
• Status: Active Grant

• Current Assignee: NLT Technologies, Ltd.
• Original Assignee: NLT Technologies, Ltd.
• Inventors: Sakamoto, Michiaki, Matsushima, Jin, Nagai, Hiroshi, Mori, Kenichi, Ikeno, Hidenori, Kudo, Yasuki, Sumiyoshi, Ken
• Primary Examiner(s): NGO, HUYEN LE
• Application Number:
  US13/833,843
• Publication Number:
  US 20130208199A1
• Time in Patent Office: 641 Days
• Field of Search: 349/114, 349/141, 349/96, 349/103
• US Class Current: 349/114
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
• CPC Class Codes: G09G 2300/0408 Integration of the drivers onto the display substrate
• CPC Class Codes: G09G 2300/0456 with a reflective area and a transmissive area combined in one pixel, such as in transflectance pixels
• CPC Class Codes: G09G 2320/028 by changing the viewing angle properties, e.g. widening the viewing angle, adapting the viewing angle to the view direction
• CPC Class Codes: G09G 3/3655 Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors
• CPC Class Codes: G09G 3/3659 the addressing of the pixel involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependant on signal of two data electrodes

Abstract

An IPS-mode transflective LCD device includes an array of pixels each including a reflective region and a transmissive region. The reflective region operates in a normally-white mode, and the transmissive region operates in a normally-black mode. A first potential is applied to a liquid crystal layer in the reflective region, and a second potential is applied to the liquid crystal layer in the transmissive region. The first and second potential have therebetween an opposite magnitude relationship in each of the pixels.

Claims

1. A method for driving a transflective liquid crystal display (LCD) device including pixels arranged in an array, each of said pixels having a reflective region on which a first pixel electrode connected to a data line via a first switching device wherein a pixel signal is supplied to said data line, a first common electrode and a reflection film are formed, each of said pixel having a transmissive region on which a second pixel electrode connected to said data line via a second switching device, and a second common electrode are formed, and each of said pixels having a common gate line in which said first switching device and said second switching device are respectively connected thereto, said method comprising the steps of:

applying a first potential to a liquid crystal layer in said reflective region, and applying a second potential to said liquid crystal layer in said transmissive region, said first potential and said second potential therebetween are opposite magnitudes in each of said pixels, which are due to said first switching device and said second switching device connected to said common gate line being turned ON and a common pixel signal to said first pixel electrode and said second pixel electrode being supplied, and further a first common signal being supplied to said first common electrode, and a second common signal being supplied to said second common electrode, said second common signal being a substantially inverted signal of said first common signal.

2. The method according to claim 1, wherein said opposite magnitudes is such that, when one of said first potential and said second potential is a maximum gray-scale-level potential, the other is a minimum gray-scale-level potential in each of said pixels.

3. A method for driving a transflective liquid crystal display LCD) device including pixels arranged in an array, each of said pixels having a reflective region on which a first pixel electrode connected to a data line via a first switching device wherein a pixel signal is supplied to said data line, a common electrode and a reflection film are formed, and said pixel having a transmissive region on which a second pixel electrode connected to said data line via a second switching device, and said common electrode are formed, wherein said LCD device includes a first gate line for controlling said first switching device, and a second gate line for controlling said second switching device, and said common electrode formed on said reflective region and said transmissive region is connected to a common electrode line, said method comprising the steps of:

turning ON, in a time-division scheme, said first switching device to supply said pixel signal to said first pixel electrode, and said second switching device to supply said pixel signal to said second pixel electrode and

applying different potentials to said common electrode line during a time period in which said first switching device is turned ON and said pixel signal is supplied to said first pixel electrode, and during a time period in which said second switching device is turned ON and said pixel signal is supplied to said second pixel electrode.

4. A method for driving a transflective liquid crystal display (LCD) device including pixels arranged in an array, each of said pixels having a reflective region on which a first pixel electrode connected to a data line via a first switching device wherein a pixel signal is supplied to said data line, a common electrode and a reflection film are formed, and said pixel having a transmissive region on which a second pixel electrode connected to said data line via a second switching device, and said common electrode are formed, wherein said LCD device includes a first gate line for controlling said first switching device, and a second gate line for controlling said second switching device, and said common electrode formed on said reflective region and said transmissive region is connected to a common electrode line, said method comprising the step of:

turning ON in a time-division scheme, said first switching device to supply said pixel signal to said first pixel electrode, and said second switching device to supply said pixel signal to second pixel electrode and

applying different potentials to said data line, and applying same potentials to said common electrode line during a reflective-selection time period in which said first switching device is turned ON and a pixels signal is supplied to said first pixel electrode, and during a transmissive-selection time period in which said second switching device is turned ON and a pixel signal is supplied to said second pixel electrode.

5. The method according to claim 4, wherein

a pixel signal supplied during either said reflective-selection time period or said transmissive-selection time period is converted based on the gray-scale of a pixel supplied to said data line during the other time period using a look-up table.

6. The method according to claim 5, wherein said look-up table contains a conversion value obtained by matching a gamma-characteristic of said reflective region with a gamma-characteristic of said transmissive region.

7. A method for driving a transflective liquid crystal display (LCD) device including pixels arranged in an array, each of said pixels having a reflective region on which a first pixel electrode connected to a data line via a first switching device wherein a pixel signal is supplied to said data line, a common electrode and a reflection film are formed, and said pixel having a transmissive region on which a second pixel electrode connected to said data line via a second switching device, and said common electrode are formed, wherein said LCD device includes a first gate line for controlling said first switching device, and a second gate line for controlling said second switching device, and said common electrode formed on said reflective region and said transmissive region is connected to a common electrode line, said method comprising the steps of:

turning ON, in a time-division scheme, said first switching device to supply said pixel signal to said first pixel electrode, and said second switching device to supply said pixel signal to second pixel electrode and

applying a first common signal to said common electrode during a time period in which said first switching device is turned ON and said pixel signal is supplied to said first pixel electrode; and

applying a second common signal to said common electrode during a time period in which said second switching device is turned ON and said pixel signal is supplied to said second pixel electrode, said second common signal being substantially an inverted signal of said first common signal.