Display apparatus

• US 8,354,978 B2
• Filed: 08/17/2006
• Issued: 01/15/2013
• Est. Priority Date: 02/17/1997
• Status: Expired due to Term

• Current Assignee: Intellectual Keystone Technology LLC
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Ozawa, Tokuroh, Kimura, Mutsumi
• Primary Examiner(s): Nguyen, Kevin M
• Assistant Examiner(s): ALMEIDA, CORY A
• Application Number:
  US11/505,457
• Publication Number:
  US 20060273995A1
• Time in Patent Office: 2,343 Days
• Field of Search: 345 76- 83, 345/92, 345/93, 345/97, 345 98-204, 345/206, 345/210, 345/211
• US Class Current: 345/76
• CPC Class Codes: G09G 2300/0408 Integration of the drivers onto the display substrate
• CPC Class Codes: G09G 2300/0417 Special arrangements specific to the use of low carrier mobility technology
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2300/0439 Pixel structures
• CPC Class Codes: G09G 2300/0465 Improved aperture ratio, e.g. by size reduction of the pixel circuit, e.g. for improving the pixel density or the maximum displayable luminance or brightness
• CPC Class Codes: G09G 2300/08 Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0847 being a dynamic memory without any storage capacitor, i.e. with use of parasitic capacitances as storage elements
• CPC Class Codes: G09G 2300/0876 Supplementary capacities in pixels having special driving circuits and electrodes instead of being connected to common electrode or ground; Use of additional capacitively coupled compensation electrodes
• CPC Class Codes: G09G 2310/0254 Control of polarity reversal in general, other than for liquid crystal displays
• CPC Class Codes: G09G 2310/0256 with the purpose of reversing the voltage across a light emitting or modulating element within a pixel
• CPC Class Codes: G09G 2310/0262 The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
• CPC Class Codes: G09G 2310/0283 Arrangement of drivers for different directions of scanning
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• 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
• CPC Class Codes: G09G 3/3258 with pixel circuitry controlling the voltage across the light-emitting element
• CPC Class Codes: G09G 3/3266 : Details of drivers for scan electrodes
• CPC Class Codes: H10K 2102/3026 : Top emission
• CPC Class Codes: H10K 50/81 : Anodes
• CPC Class Codes: H10K 50/828 : Transparent cathodes, e.g. comprising thin metal layers
• CPC Class Codes: H10K 50/86 : Arrangements for improving contrast, e.g. preventing reflection of ambient light
• CPC Class Codes: H10K 50/865 : comprising light absorbing layers, e.g. light-blocking layers
• CPC Class Codes: H10K 59/12 : Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 59/1213 : the pixel elements being TFTs
• CPC Class Codes: H10K 59/122 : Pixel-defining structures or layers, e.g. banks
• CPC Class Codes: H10K 59/131 : Interconnections, e.g. wiring lines or terminals
• CPC Class Codes: H10K 71/135 : using ink-jet printing

Abstract

A display apparatus, that includes current driving type luminescent elements, has a driving system that takes the conduction types of TFTs to control the emission of the luminescent elements into consideration. In order to reduce driving voltage and improve display quality simultaneously, the arrangement is provided such that if the second TFT which performs the “on-off” function of the current for the luminescent element is of an N channel type, the potential of the common power supply line (“com”) is lowered below the potential of the opposite electrode (“op”) of the luminescent element to obtain a higher gate voltage (“Vgcur”). In this case, if the first TFT connected to the gate of the second TFT is of a P channel type, when using the potential of the potential-holding electrode (“st”) at the “on” state as a reference, potentials of the scanning signal (“Sgate”) at the lower potential and the common power supply line (“com”) are rendered of the same polarities with respect to this potential of the potential-holding electrode (“st”). Therefore, the potential of the image signal (“data”) to turn “on” can be shifted within the range of the driving voltage in the display apparatus in the direction to reduce resistances at the “on” states of the first TFT and the second TFT to reduce driving voltage and improve display quality.

Claims

1. An electroluminescent apparatus comprising:

a plurality of scanning lines;

a plurality of data lines;

a power supply line formed in a first layer, the power supply line providing power to a luminescent element;

a capacitor line formed in a second layer, the capacitor line intersecting the power supply line; and

a plurality of pixels, each pixel corresponding to an intersection of one of the scanning lines and one of the data lines, the each pixel including;

a pixel electrode;

an opposite electrode opposed to the pixel electrode;

the luminescent element emitting light based on a current flowing from the power supply line to the pixel electrode and between the pixel electrode and the opposite electrode;

a first transistor having a first gate electrode that is coupled to one of the scanning lines;

a second transistor having a second gate electrode, the second transistor controlling the current; and

a holding capacitor holding a charge based on a signal supplied through one of the data lines and the first transistor, the holding capacitor including a first electrode and a second electrode opposing the first electrode, each of the first and second electrodes being formed on different layers, where a portion of the capacitor line is the second electrode, the power supply line being continuous over the plurality of the pixels.

2. The electroluminescent apparatus according to claim 1, wherein the capacitor line extends parallel with the scanning lines.

3. An electroluminescent apparatus comprising:

a plurality of scanning lines;

a plurality of data lines;

a power supply line formed in a first layer, the power supply line providing power to a luminescent element;

a capacitor line formed in a second layer, the capacitor line crossing the power supply line; and

a plurality of pixels, each pixel corresponding to an intersection of one of the scanning lines and one of the data lines, the each pixel including;

a pixel electrode;

an opposite electrode opposed to the pixel electrode;

the luminescent element emitting light based on a current flowing from the power supply line to the pixel electrode and between the pixel electrode and the opposite electrode;

a first transistor having a first gate electrode coupled to one of the scanning lines;

a second transistor having a second gate electrode, the second transistor electrically coupled between the power supply line and the luminescent element; and

a holding capacitor holding a charge based on a first signal supplied through one of the data lines, the holding capacitor including a first electrode and a second electrode opposing the first electrode, each of the first and second electrodes being formed on different layers, where a portion of the capacitor line is the second electrode, the power supply line being continuous over the plurality of the pixels.

4. The electroluminescent apparatus according to claim 3, the first electrode being electrically coupled to the second gate electrode.

5. The electroluminescent apparatus according to claim 3, further comprising:

a scanning line driving circuit coupled to the capacitor line.

6. The electroluminescent apparatus according to claim 3, wherein a potential of a second signal supplied to the second electrode of the holding capacitor through one of the scanning lines is time varying.

7. The electroluminescent apparatus according to claim 3, wherein a potential of a second signal supplied to the second electrode of the holding capacitor through the capacitor line varies behind a change of a potential of a scanning signal supplied through one of the scanning lines.

8. An electroluminescent apparatus comprising:

a plurality of scanning lines;

a plurality of data lines;

a power supply line formed in a first layer, the power supply line providing power to a luminescent element, the power supply line following a first direction;

a capacitor line formed in a second layer, the capacitor line following a second direction intersecting the first direction; and

a plurality of pixels, each pixel corresponding to an intersection of one of the scanning lines and one of the data lines, the each pixel including;

a pixel electrode;

an opposite electrode opposed to the pixel electrode;

the luminescent element emitting light based on a current flowing from the power supply line to the pixel electrode and between the pixel electrode and the opposite electrode;

a first transistor having a first gate electrode coupled to one of the scanning lines;

a second transistor having a second gate electrode, the second transistor electrically coupled between the power supply line and the luminescent element; and

a holding capacitor holding a charge based on a signal supplied through one of the data lines, the holding capacitor including a first electrode and a second electrode opposing the first electrode, each of the first and second electrodes being formed on different layers, where a portion of the capacitor line is the second electrode, the power supply line being continuous over the plurality of the pixels.

9. The electroluminescent apparatus according to claim 8, the first electrode being electrically coupled to the second gate electrode.

10. The electroluminescent apparatus according to claim 8, the data lines following the first direction, and the scanning lines following the second direction.

11. An electroluminescent apparatus comprising:

a plurality of scanning lines;

a plurality of data lines;

a power supply line that is a first wiring line and provides power to a luminescent element;

a capacitor line that is a second wiring line, the capacitor line intersecting the power supply line; and

a plurality of pixels, each pixel corresponding to an intersection of one of the scanning lines and one of the data lines, the each pixel including;

a pixel electrode;

an opposite electrode opposed to the pixel electrode;

the luminescent element emitting light based on a current flowing from the power supply line to the pixel electrode and between the pixel electrode and the opposite electrode;

a first transistor having a first gate electrode that is coupled to one of the scanning lines;

a second transistor having a second gate electrode, the second transistor controlling the current; and

a holding capacitor holding a charge based on a signal supplied through one of the data lines and the first transistor, the holding capacitor including a first electrode and a second electrode opposing the first electrode, each of the first and second electrodes being formed on different layers, where a portion of the capacitor line is the second electrode, the power supply line being continuous over the plurality of the pixels.

12. The electroluminescent apparatus according to claim 11, wherein the capacitor line extends parallel with the scanning lines.

13. An electroluminescent apparatus comprising:

a plurality of scanning lines;

a plurality of data lines;

a power supply line that is a first wiring line and provides power to a luminescent element;

a capacitor line that is a second wiring line, the capacitor line crossing the power supply line; and

a plurality of pixels, each pixel corresponding to an intersection of one of the scanning lines and one of the data lines, the each pixel including;

a pixel electrode;

an opposite electrode opposed to the pixel electrode;

the luminescent element emitting light based on a current flowing from the power supply line to the pixel electrode and between the pixel electrode and the opposite electrode;

a first transistor having a first gate electrode coupled to one of the scanning lines;

a second transistor having a second gate electrode, the second transistor electrically coupled between the power supply line and the luminescent element; and

a holding capacitor holding a charge based on a first signal supplied through one of the data lines, the holding capacitor including a first electrode and a second electrode opposing the first electrode, each of the first and second electrodes being formed on different layers, where a portion of the capacitor line is the second electrode, the power supply line being continuous over the plurality of the pixels.

14. The electroluminescent apparatus according to claim 13, the first electrode being electrically coupled to the second gate electrode.

15. The electroluminescent apparatus according to claim 13, further comprising:

a scanning line driving circuit coupled to the capacitor line.

16. The electroluminescent apparatus according to claim 13, wherein a potential of a second signal supplied to the second electrode of the holding capacitor through one of the scanning lines is time varying.

17. The electroluminescent apparatus according to claim 13, wherein a potential of a second signal supplied to the second electrode of the holding capacitor through the capacitor line varies behind a change of a potential of a scanning signal supplied through one of the scanning lines.

18. An electroluminescent apparatus comprising:

a plurality of scanning lines;

a plurality of data lines;

a power supply line that is a first wiring line and provides power to a luminescent element, the power supply line following a first direction;

a capacitor line that is a second wiring line, the capacitor line following a second direction intersecting the first direction; and

a plurality of pixels, each pixel corresponding to an intersection of one of the scanning lines and one of the data lines, the each pixel including;

a pixel electrode;

an opposite electrode opposed to the pixel electrode;

the luminescent element emitting light based on a current flowing from the power supply line to the pixel electrode and between the pixel electrode and the opposite electrode;

a first transistor having a first gate electrode coupled to one of the scanning lines;

a second transistor having a second gate electrode, the second transistor electrically coupled between the power supply line and the luminescent element; and

a holding capacitor holding a charge based on a signal supplied through one of the data lines, the holding capacitor including a first electrode and a second electrode opposing the first electrode, each of the first and second electrodes being formed on different layers, where a portion of the capacitor line is the second electrode, the first power supply line being continuous over the plurality of the pixels.

19. The electroluminescent apparatus according to claim 18, the first electrode being electrically coupled to the second gate electrode.

20. The electroluminescent apparatus according to claim 18, the data lines following the first direction, and the scanning lines following the second direction.