Display Apparatus

• US 20080246700A1
• Filed: 06/10/2008
• Published: 10/09/2008
• Est. Priority Date: 02/17/1997
• Status: Abandoned Application

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Kimura, Mutsumi, Ozawa, Tokuroh
• Application Number:
  US12/155,813
• Publication Number:
  US 20080246700A1
• Time in Patent Office: Days
• 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 electro-luminescent apparatus comprising:

scanning lines;

data lines;

power supply lines;

pixel electrodes;

an opposite electrode formed to oppose the pixel electrodes;

luminescent elements, one luminescent element being interposed between one pixel electrode of the pixel electrodes and the opposite electrode;

first transistors, one first transistor of the first transistors having a gate electrode connected to one of the data lines; and

second transistors, one second transistor of the second transistors being connected between one pixel electrode of the pixel electrodes and one power supply line of the power supply lines,

when the one second transistor is in an “

on”

state;

a potential of the one power supply line of the power supply lines being higher than a potential of the opposite electrode, and a potential of a gate electrode of the one second transistor of the second transistors being higher than or being equal to the potential of the opposite electrode.

2. The electro-luminescent apparatus of claim 1,

wherein the second transistors are P-channel type.

3. An electro-luminescent apparatus comprising:

scanning lines;

data lines;

power supply lines;

pixel electrodes;

an opposite electrode formed to oppose the pixel electrodes;

luminescent elements, one luminescent element of the luminescent elements being interposed between one pixel electrode of the pixel electrodes and the opposite electrode;

first transistors, one first transistor of the first transistors having a gate electrode connected to one of the data lines; and

second transistors, one second transistor of the second transistors being connected between one pixel electrode of the pixel electrodes and one power supply line of the power supply lines,

when the one second transistor is in an “

off”

state;

a potential of the one power supply line of the power supply lines being higher than a potential of the opposite electrode, and a potential of a gate electrode of the one second transistor of the second transistors being higher than or being equal to the potential of the opposite electrode.

4. The electro-luminescent apparatus of claim 3,

wherein the second transistors are P-channel type.

5. An electro-luminescent apparatus comprising:

scanning lines;

data lines;

power supply lines;

pixel electrodes;

an opposite electrode formed to oppose the pixel electrodes;

luminescent elements, one luminescent element of the luminescent elements being interposed between one pixel electrode of the pixel electrodes and the opposite electrode;

first transistors, one first transistor of the first transistors having a gate electrode connected to one of the data lines; and

second transistors, one second transistor of the second transistors being connected between one pixel electrode of the pixel electrodes and one power supply line of the power supply lines,

when the one second transistor is in an “

on”

state;

a potential of the one power supply line of the plurality of power supply lines being lower than a potential of the opposite electrode, and a potential of a gate electrode of the one second transistor of the second transistors being lower than or being equal to the potential of the opposite electrode.

6. The electro-luminescent apparatus of claim 5,

wherein the second transistors are N-channel type.

7. An electro-luminescent apparatus comprising:

scanning lines;

data lines;

power supply lines;

pixel electrodes;

an opposite electrode formed to oppose the pixel electrodes;

luminescent elements, one luminescent element of the luminescent elements being interposed between one pixel electrode of the pixel electrodes and the opposite electrode;

first transistors, one first transistor of the first transistors having a gate electrode connected to one of the data lines; and

second transistors, one second transistor of the second transistors being connected between one pixel electrode of the pixel electrodes and one power supply line of the power supply lines,

when the one second transistor is in an “

off”

state;

a potential of the one power supply line of the plurality of power supply lines being lower than a potential of the opposite electrode, and a potential of a gate electrode of the one second transistor of the second transistors being lower than or being equal to the potential of the opposite electrode.

8. The electro-luminescent apparatus of claim 7,

wherein the second transistors are N-channel type.

9. An electro-luminescent apparatus comprising:

scanning lines;

data lines;

power supply lines;

pixel electrodes;

an opposite electrode formed to oppose the pixel electrodes;

luminescent elements, one luminescent element of the luminescent elements being interposed between one pixel electrode of the pixel electrodes and the opposite electrode;

first transistors, one first transistor of the first transistors having a gate electrode connected to one of the data lines; and

second transistors, one second transistor of the second transistors being connected between one pixel electrode of the pixel electrodes and one power supply line of the power supply lines,

when the second transistor is in an “

on”

state;

a potential of the one power supply line of the power supply lines being higher than a potential of the opposite electrode, and a potential of the data signal to be supplied to the data line connected to the one second transistor of the second transistors being higher than or being equal to the potential of the opposite electrode.

10. The electro-luminescent apparatus of claim 9,

wherein the second transistors are P-channel type.

11. An electro-luminescent apparatus comprising:

scanning lines;

data lines;

power supply lines;

pixel electrodes;

an opposite electrode formed to oppose the pixel electrodes;

luminescent elements, one luminescent element of the luminescent elements being interposed between one pixel electrode of the pixel electrodes and the opposite electrode;

first transistors, one first transistor of the first transistors having a gate electrode connected to one of the data lines; and

second transistors, one second transistor of the second transistors being connected between one pixel electrode of the pixel electrodes and one power supply line of the power supply lines,

when the one second transistor is in an “

off”

state;

a potential of the one power supply line of the power supply lines being higher than a potential of the opposite electrode, and a potential of the data signal to be supplied to the data line connected to the one second transistor of the second transistors being lower than or being equal to the potential of the common electrode.

12. The electro-luminescent apparatus of claim 11,

wherein the second transistors are P-channel type.

13. An electro-luminescent apparatus comprising:

scanning lines;

data lines;

power supply lines;

pixel electrodes;

an opposite electrode formed to oppose the pixel electrodes;

luminescent elements, one luminescent element of the luminescent elements being interposed between one pixel electrode of the pixel electrodes and the opposite electrode;

first transistors, one first transistor of the first transistors having a gate electrode connected to one of the data lines; and

second transistors, one second transistor of the second transistors being connected between one pixel electrode of the pixel electrodes and one power supply line of the power supply lines,

when the second transistor is in an “

on”

state;

a potential of the one power supply line of the power supply lines being higher than a potential of the opposite electrode, and a potential of the data signal to be supplied to the data line connected to the one second transistor of the second transistors being lower than or being equal to the potential of the opposite electrode.

14. The electro-luminescent apparatus of claim 13,

wherein the second transistors are N-channel type.

15. An electro-luminescent apparatus comprising:

scanning lines;

data lines;

power supply lines;

pixel electrodes;

an opposite electrode formed to oppose the pixel electrodes;

luminescent elements, one luminescent element of the luminescent elements being interposed between one pixel electrode of the pixel electrodes and the opposite electrode;

first transistors, one first transistor of the first transistors having a gate electrode connected to one of the data lines; and

second transistors, one second transistor of the second transistors being connected between one pixel electrode of the pixel electrodes and one power supply line of the power supply lines,

when the one second transistor is in an “

off”

state;

a potential of the one power supply line of the power supply lines being higher than a potential of the opposite electrode, and a potential of the data signal to be supplied to the data line connected to the one second transistor of the second transistors being higher than or being equal to the potential of the common electrode.

16. The electro-luminescent apparatus of claim 15,

wherein the second transistors are N-channel type.