Drive device and liquid crystal display apparatus

• US 10,720,119 B2
• Filed: 01/04/2017
• Issued: 07/21/2020
• Est. Priority Date: 01/27/2016
• Status: Active Grant

• Current Assignee: Trivale Technologies, LLC (Vector Capital Corporation)
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Tashiro, Tomohiro
• Primary Examiner(s): Sitta, Grant
• Application Number:
  US15/397,823
• Publication Number:
  US 20170213518A1
• Time in Patent Office: 1,294 Days
• CPC Class Codes: G09G 2310/0291 Details of output amplifiers or buffers arranged for use in a driving circuit
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 2330/02 Details of power systems and of start or stop of display operation
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2330/025 Reduction of instantaneous peaks of current
• CPC Class Codes: G09G 2330/12 Test circuits or failure detection circuits included in a display system, as permanent part thereof
• CPC Class Codes: G09G 3/2096 Details of the interface to the display terminal specific for a flat panel suitable for both CRT and flat panel G09G5/006; specific for a CRT G09G1/167
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3688 suitable for active matrices only

Abstract

A drive device according to the present invention is located in a liquid crystal panel. The drive device is a source driver IC that drives a pixel region of the liquid crystal panel. The drive device includes a comparison circuit and a determination circuit. The comparison circuit detects a potential difference between a potential of a first analog power supply and a potential of a second analog power supply, an analog power supply input from the outside being divided into the first analog power supply and the second analog power supply. The determination circuit determines that it is an abnormal condition when the potential difference detected by the comparison circuit is greater than or equal to a predetermined threshold value.

Claims

1. A drive device that is located in a liquid crystal panel and drives a pixel region of said liquid crystal panel, comprising:

a comparison circuit that detects a potential difference between a potential of a first analog power supply and a potential of a second analog power supply, an analog power supply input from the outside being divided into said first analog power supply and said second analog power supply, each of said first analog power supply and said second analog power supply is supplied to the comparison circuit;

a determination circuit that determines that it is an abnormal condition when said potential difference detected by said comparison circuit is greater than or equal to a predetermined threshold value, and controls said drive device to reduce a current output to said pixel region of said liquid crystal panel;

an auxiliary circuit that includes a PMOS transistor and an NMOS transistor and supports an output to said pixel region;

a first control switch that controls an operation of said PMOS transistor; and

a second control switch that controls an operation of said NMOS transistor, wherein

when said determination circuit determines that it is said abnormal condition, said first control switch and said second control switch respectively control said PMOS transistor and said NMOS transistor so as not to turn them ON simultaneously.

2. The drive device according to claim 1, further comprising:

an output amplifier; and

a current control circuit that controls an amount of current output from said output amplifier to said pixel region,

wherein said current control circuit controls said amount of current so as to reduce the current output from said output amplifier when said determination circuit determines that it is said abnormal condition.

3. The drive device according to claim 1, wherein said determination circuit outputs a signal for indicating said abnormal condition to the outside when determining that it is said abnormal condition.

4. A liquid crystal display apparatus, comprising the drive device according to claim 1.

5. The liquid crystal display apparatus according to claim 4, wherein

said first analog power supply and said second analog power supply are supplied to said drive device via a flexible printed circuit (FPC),

said liquid crystal panel includes a first connection terminal of said first analog power supply that can be connected to said FPC and a second connection terminal of said second analog power supply that can be connected to said FPC, and

one of said first connection terminal and said second connection terminal is located in a position corresponding to an end side-portion of said FPC.

6. The liquid crystal display apparatus according to claim 5, wherein one of said first analog power supply and said second analog power supply is supplied to said drive device via a stabilization circuit.

7. The drive device according to claim 1, wherein, when said determination circuit determines that it is said abnormal condition, each of said first control switch and said second control switch receives an abnormal condition determination signal from said determination circuit, and said first control switch and said second control switch control said PMOS transistor and said NMOS transistor, respectively, so as not to turn them ON simultaneously and to reduce the current output to said pixel region of said liquid crystal panel.