Transflective liquid crystal display device having first and second data drivers and generating first and second signals of different voltage values

• US 7,777,840 B2
• Filed: 03/14/2005
• Issued: 08/17/2010
• Est. Priority Date: 09/09/2004
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Enomoto, Hiromi, Okazaki, Susumu
• Primary Examiner(s): Nelms; David
• Assistant Examiner(s): Nguyen; Lauren
• Application Number:
  US11/079,931
• Publication Number:
  US 20060050208A1
• Time in Patent Office: 1,982 Days
• Field of Search: 349/114, 349/39
• US Class Current: 349/114
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/134345 Subdivided pixels, e.g. for grey scale or redundancy
• CPC Class Codes: G02F 1/13624 having more than one switching element per pixel
• CPC Class Codes: G02F 1/1393 the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells G02F1/1396, G02F1/141 take precedence

Abstract

A reflective electrode, a transparent electrode, a TFT connected to the reflective electrode and a TFT connected to the transparent electrode are formed in each picture element. A first data signal is written into the reflective electrode via the TFT, a second data signal is written into the transparent electrode via the TFT. In this way, the individual data signals are respectively written into the reflective electrode and the transparent electrode, and thereby excellent display quality can be obtained either when used as a transmissive liquid crystal display device or when used as a reflective liquid crystal display device.

Claims

1. A transflective liquid crystal display device which is configured of first and second substrates and a liquid crystal layer placed between the first and second substrates, and which includes a reflective region for controlling the amount of reflected light and a transmissive region for controlling the amount of transmitted light, the transflective liquid crystal display device comprising:

a reflective electrode placed on the reflective region of the first substrate;

a transparent electrode which is placed on the transmissive region of the first substrate and is electrically isolated from the reflective electrode;

a first thin film transistor which is formed on the first substrate and is connected to the reflective electrode;

a second thin film transistor which is formed on the first substrate and is connected to the transparent electrode;

a common electrode which is formed on the second substrate and is placed to face both the reflective electrode and the transparent electrode;

a voltage generation unit generating a common voltage which is supplied to the common electrode and is changed every frame; and

a first data driver for supplying a first data signal to the reflective electrode via the first thin film transistor and a second data driver for supplying a second data signal to the transparent electrode via the second thin film transistor;

a first auxiliary capacitor connected to the reflective electrode;

a second auxiliary capacitor which is connected to the transparent electrode, wherein at least a portion of said second auxiliary capacitor is placed on a boundary portion between the reflective region and the transmissive region, where said boundary portion is a portion lacking both the reflective electrode and the transparent electrode;

wherein the first and second data drivers receive the same display signals and generate the first and second data signals such that a voltage value of the first signal is less than a voltage value of the second signal.

2. The transflective liquid crystal display device according to claim 1,

wherein the first and second thin film transistors are connected to the same data bus line.

3. The transflective liquid crystal display device according to claim 1,

wherein the second thin film transistor is covered with the reflective electrode.

4. The transflective liquid crystal display device according to claim 1, further comprising a data signal selection switch which is interposed between both of the first and second data drivers and both of the first and second thin film transistors, receives the first and second data signals outputted from the first and second data drivers, and transmits the first and second data signals to the first and second thin film transistors respectively in such a manner that the first and second data signals are sequentially switched to each other.

5. The transflective liquid crystal display device according to claim 1, further comprising:

a first gate driver for supplying a first gate signal to the gate of the first thin film transistor;

a second gate driver for supplying a second gate signal to the gate of the second thin film transistor; and

a control unit for driving the first and second gate drivers in synchronization with each other.