EL DISPLAY DEVICE

• US 20090109142A1
• Filed: 03/28/2008
• Published: 04/30/2009
• Est. Priority Date: 03/29/2007
• Status: Abandoned Application

• Current Assignee: Toshiba Matsushita Display Technology (Japan Display Incorporated)
• Original Assignee: Toshiba Matsushita Display Technology (Japan Display Incorporated)
• Inventors: Takahara, Hiroshi
• Application Number:
  US12/058,149
• Publication Number:
  US 20090109142A1
• Time in Patent Office: Days
• US Class Current: 345/76
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• 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 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 3/006 Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

A switch being turned off using an output open function of a power supply circuit, a cathode voltage Vss is not transmitted, an output terminal takes on a high impedance condition and, a probing being done into a pad of the cathode voltage Vss output terminal with a probe, an ammeter which measures a current is disposed between the probe 304 and an external power source Vsst, making an adjustment time cathode voltage Vsst equal to an image display time cathode voltage Vss.

Claims

1. An EL display device comprising:

a display screen in which a plurality of EL elements are disposed in a matrix formation;

a source drive circuit which, being connected to each EL element, supplies an image signal to each EL element;

a gate drive circuit connected to each EL element; and

an extraction terminal which, as well as supplying a drive voltage to each EL element via a voltage output terminal, has a switch which open-circuits or short-circuits each EL element and the voltage output terminal and, being disposed between each EL element and the switch, extracts a current flowing through each EL terminal.

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

a test signal supply module which, using the source drive circuit, supplies a white image signal or a black image signal to each EL element; and

a current measurement module which, when the white image signal or the black image signal is supplied to each EL element, open-circuits the voltage output terminal by means of the switch, and measures a current flowing through the extraction terminal.

3. The EL display device according to claim 1, further comprising:

an aging current supply module which open-circuits the voltage output terminal by means of the switch, and supplies an aging current to the extraction terminal.

4. An EL display device comprising:

a display screen in which EL elements are disposed in a matrix formation;

a power supply circuit which has a function of open-circuiting a voltage output terminal; and

an extraction terminal which extracts a current flowing through the display screen.

5. The EL display device according to claim 4, wherein

a current flowing through the extraction terminal is measured by a current measurement module.

6. The EL display device according to claim 4, wherein

the power supply circuit switches the voltage output terminal between a high impedance condition and a voltage output condition.

7. An EL display device having a display screen in which pixels having the EL elements formed therein are disposed in a matrix formation, comprising:

a gate drive circuit which selects the pixels;

a voltage generation circuit which generates a first voltage applied to the gate drive circuit, and a second voltage applied to the pixels;

a power supply wiring which transmits the second voltage generated by the voltage generation circuit to the pixels of the display screen; and

an output open circuit which places the second voltage output of the voltage generation circuit in an open condition, wherein

a drive transistor which supplies a current to each EL element is formed in each pixel, and

after the voltage generation circuit supplies the first voltage to the gate drive circuit, the output open circuit takes on a closed condition, applying the second voltage generated by the voltage generation circuit to the power supply wiring.

8. The EL display device according to claim 7, wherein

the power supply wiring is an anode wiring or a cathode wiring.

9. The EL display device according to claim 7, wherein

the voltage generation circuit can set a plurality of current limit values.

10. The EL display device according to claim 7, wherein

the first voltage and the second voltage are variable.

11. The EL display device according to claim 7, further comprising:

a clock detection circuit, wherein

an output of the voltage generation circuit is controlled by means of a number of clocks detected by the clock detection circuit.