Display apparatus

• US 6,839,045 B2
• Filed: 02/11/2002
• Issued: 01/04/2005
• Est. Priority Date: 02/17/1997
• Status: Expired due to Term

• Current Assignee: Intellectual Keystone Technology LLC (Samsung Electronics Co. Ltd.)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Kimura, Mutsumi, Ozawa, Tokuroh
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): LESPERANCE, JEAN E
• Application Number:
  US10/068,890
• Publication Number:
  US 20020097213A1
• Time in Patent Office: 1,058 Days
• Field of Search: 345/92, 345/93, 345/87, 345/94, 345/96, 345/88, 345/102, 345/103, 345/74.1, 345/75.1, 345/76, 345/82, 345/71, 345/45, 345/46, 345/47
• US Class Current: 345/92
• 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 59/8051 : Anodes
• CPC Class Codes: H10K 59/80524 : Transparent cathodes, e.g. comprising thin metal layers
• 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. A display apparatus comprising:

a substrate; and

a plurality of luminescent elements, each of the luminescent elements being provided between a pixel electrode and an opposite electrode opposed to the pixel electrode, each of the plurality of luminescent elements being divided by a bank from each other, each of the plurality of luminescent elements including an emitting thin film that is surrounded by the bank,

a light from the emitting thin film emitting toward a direction opposite to the substrate with respect to the emitting thin film through the opposite electrode.

2. The display apparatus according to claim 1, further comprising at least one transistor connected to the pixel electrode.

3. The display apparatus according to claim 2, the at least one transistor being disposed on the substrate.

4. The display apparatus according to claim 1, the opposite electrode being transparent.

5. The display apparatus according to claim 1, the pixel electrode being a positive electrode, and the opposite electrode being a negative electrode.

6. The display apparatus according to claim 1, the pixel electrode being a negative electrode, and the opposite electrode being a positive electrode.

7. The display apparatus according to claim 1, further including a hole injection layer between the emitting thin film and the opposite electrode.

8. The display apparatus according to claim 1, further including a hole injection layer between the emitting thin film and the pixel electrode.

9. The display apparatus according to claim 1, the emitting thin film being formed of organic semiconductor material.

10. The display apparatus according to claim 1, the pixel electrode comprising a metal film.

11. A display apparatus comprising:

a substrate;

a data line;

a scanning line;

a common power supply line;

a first transistor, the first transistor having a gate electrode connected to the scanning line, and source or drain region connected to the data line;

a second transistor, the second transistor being turned on according to a signal supplied through the first transistor and the data line;

a bank;

a pixel electrode, the pixel electrode being connected to the second transistor; and

;

a plurality of luminescent elements, each of the plurality of luminescent elements being provided between a pixel electrode and an opposite electrode opposed to the pixel electrode, each of the plurality of luminescent elements being divided by a bank from each other,

the pixel electrode being connected to the second transistor,

each of the plurality of luminescent elements including an emitting thin film that is provided between the pixel electrode and the opposite electrode opposed to the pixel electrode, the emitting thin film emits a light when a current flows between the common power supply line and the opposite electrode through the second transistor and the pixel electrode, the emitting thin film being surrounded by the bank;

a light from the emitting thin film emitting toward a direction opposite to the substrate with respect to the luminescent element through the opposite electrode.

12. The display apparatus according to claim 11,

the second transistor being of P channel type, and the potential of the common power supply line being set at a higher level than the potential of the opposite electrode.

13. The display apparatus according to claim 11,

the second transistor being of N channel type, and the potential of the common power supply line being set at a lower level than the potential of the opposite electrode.

14. A display apparatus comprising:

a substrate;

a data line;

a scanning line;

a common power supply line;

a first transistor having a gate electrode connected to the scanning line, and source or drain region connected to the data line;

a second transistor, the second transistor being turned on according to a signal supplied through the first transistor and the data line;

at least one insulation-film disposed on the data line, the first transistor, and the second transistor;

a bank formed on the at least one insulation-film; and

a plurality of luminescent elements, each of the plurality of luminescent elements being provided between a pixel electrode and an opposite electrode opposed to the pixel electrode, each of the plurality of luminescent elements being divided by the bank from each other,

each of the plurality of luminescent elements including an emitting thin film provided between a pixel electrode and an opposite electrode opposed to the pixel electrode, the emitting thin film emits a light when a current flows between the common power supply line and the opposite electrode through the second transistor and the pixel electrode, and the emitting thin film being surrounded by the bank;

the second transistor being connected to the pixel electrode; and

a light from the emitting thin film emitting toward a direction opposite to the substrate with respect to the emitting thin film through the opposite electrode.

15. A display apparatus comprising:

a substrate;

a data line;

a scanning line;

a common power supply line;

a first transistor, the first transistor having a gate electrode connected to the scanning line, and source or drain region connected to the data line;

a second transistor, the second transistor being turned on according to a signal supplied through the first transistor and the data line;

at least one insulation-film formed on the data line and the first transistor and the second transistor;

a pixel electrode formed on the at least one insulation-film, the pixel electrode being connected to the second transistor through a contact hole formed in the at least one insulation-film;

a bank formed on the at least one insulation-film; and

a plurality of luminescent elements, each of the plurality of luminescent elements being provided between the pixel electrode and an opposite electrode opposed to the pixel electrode, each of the plurality of luminescent elements being divided by the bank from each other,

each of the plurality of luminescent elements including an emitting thin film provided between the pixel electrode and an opposite electrode opposed to the pixel electrode, the emitting thin film emits a light when a current flows between the common power supply line and the opposite electrode through the second transistor and the pixel electrode;

the emitting film being surrounded by the bank,

a light from the emitting thin film emitting toward a direction opposite to the substrate with respect to the emitting thin film through the opposite electrode.

16. A display apparatus comprising:

a substrate;

a plurality of luminescent elements, each of the plurality of luminescent elements being provided between a pixel electrode and an opposite electrode opposed to the pixel electrode, each of the plurality of luminescent elements being divided by a bank from each other,

each of the plurality of luminescent elements including an emitting thin film provided between the pixel electrode and the opposite electrode; and

the bank surrounding the emitting thin film,

a light from each of the plurality of luminescent elements emitting toward a direction opposite to the substrate with respect to the emitting thin film through the opposite electrode.

17. The display apparatus according to claim 16, the opposite electrode covering the bank.

18. A display apparatus comprising:

a substrate;

a plurality of luminescent elements, each of the plurality of luminescent elements being provided between a pixel electrode and an opposite electrode opposed to the pixel electrode, each of the plurality of luminescent elements being divided by a bank from each other,

each of the plurality of luminescent elements including an emitting thin film provided between the pixel electrode and the opposite electrode opposed to the pixel electrode; and

an insulating layer surrounding the emitting thin film,

a light from each of the plurality of luminescent elements emitting toward a direction opposite to the substrate with respect to the emitting thin film through the opposite electrode, and

the opposite electrode covering the insulation layer.