Display apparatus and method of driving the same

• US 7,576,718 B2
• Filed: 09/09/2004
• Issued: 08/18/2009
• Est. Priority Date: 11/28/2003
• Status: Active Grant

• Current Assignee: EL Technology Fusion Godo Kaisha
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Miyazawa, Takao
• Primary Examiner(s): Hjerpe; Richard
• Assistant Examiner(s): Shapiro; Leonid
• Application Number:
  US10/936,649
• Publication Number:
  US 20050116902A1
• Time in Patent Office: 1,804 Days
• Field of Search: 345/78, 345 76- 77, 345 80- 82, 345/204
• US Class Current: 345/78
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0852 being a dynamic memory with more than one capacitor
• CPC Class Codes: G09G 2300/0861 with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
• CPC Class Codes: G09G 2310/0248 Precharge or discharge of column electrodes before or after applying exact column voltages
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/029 by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• CPC Class Codes: G09G 2320/0295 by monitoring each display pixel
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 3/325 the data current flowing through the driving transistor during a setting phase, e.g. by using a switch for connecting the driving transistor to the data driver
• CPC Class Codes: G09G 3/3283 in which the data driver supplies a variable data current for setting the current through, or the voltage across, the light-emitting elements

Abstract

To provide a technology for preventing effect of precharging from becoming nonuniform when the threshold voltage of a driving transistor included in a current drive type pixel circuit is nonuniform. In the technology, before setting the internal state of each of current drive type pixel circuits, provided to corresponded to intersections of a plurality of data lines and a plurality of scanning lines, in accordance with light emission grayscales, precharge voltages as voltages to be applied to the data lines are specified. A predetermined current is supplied to the current drive type pixel circuits via the data lines. A precharge voltage is specified in accordance with voltages appearing in the data lines after the predetermined current is supplied.

Claims

1. A display apparatus comprising:

a plurality of data lines;

a plurality of scanning lines;

a plurality of current drive type pixels provided so as to correspond to intersections of the plurality of data lines and the plurality of scanning lines;

supplying means which supplies a predetermined current via the plurality of data lines to the corresponding pixels;

voltage measuring means which measures voltages appearing in the data lines after the supplying means supplies the predetermined current;

specifying means which specifies precharge voltages as voltages to be applied to the data lines connected to the pixels before the internal state of the pixels corresponding to light emission grayscales is set, in accordance with the voltages measured by the voltage measuring means;

a display region in which the plurality of pixels is arranged in a matrix;

calibration pixels disposed outside the display region alongside of the display region; and

switching means which selects either a first data line or a second data line for being connected to the supplying means, the first data line being connected to the pixels arranged in the display region to display an image, and the second data line being connected to the calibration pixels,

wherein the supplying means supplies the predetermined current to the calibration pixels,

wherein the specifying means specifies the precharge voltages for the corresponding calibration pixels and then, based on the distribution of the specified precharge voltages, optimizes the precharge voltages for the corresponding pixels arranged in the display region, and

wherein the calibration pixels are disposed such that the length of the second data line is smaller than that of the first data line.

2. A display apparatus comprising:

a plurality of data lines;

a plurality of scanning lines;

a plurality of current drive type pixels provided so as to correspond to intersections of the plurality of data lines and the plurality of scanning lines;

supplying means which supplies a predetermined current via the plurality of data lines to the corresponding pixels;

voltage measuring means which measures voltages appearing in the data lines after the supplying means supplies the predetermined current;

specifying means which specifies precharge voltages as voltages to be applied to the data lines connected to the pixels before the internal state of the pixels corresponding to light emission grayscales is set, in accordance with the voltages measured by the voltage measuring means; and

temperature detecting means which detects the temperature of the pixels,

wherein the specifying means specifies the precharge voltages based on the voltages appearing in the data lines and the temperature detected by the temperature detecting means.