Display device

• US 20020011981A1
• Filed: 07/17/2001
• Published: 01/31/2002
• Est. Priority Date: 07/20/2000
• Status: Abandoned Application

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Kuijk, Karel Elbert
• Application Number:
  US09/906,604
• Publication Number:
  US 20020011981A1
• Time in Patent Office: Days
• US Class Current: 345/92
• CPC Class Codes: G09G 2300/0814 used for selection purposes, e.g. logical AND for partial update
• CPC Class Codes: G09G 2300/0828 forming a digital to analog [D/A] conversion circuit
• 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 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3659 the addressing of the pixel involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependant on signal of two data electrodes

Abstract

A new switch circuit is proposed for use in display devices, comprising a series switch of complementary TFT transistors (11, 12) per pixel (8, 25). Simultaneous selection of the transistors provides low power applications. On the other hand, logic functions may be implemented.

Claims

1. A display device (1) comprising, on a substrate, a matrix of selection electrodes (5) and data electrodes (6), with a pixel and at least a field effect transistor (11) of a first type at the area of a crossing of the selection electrodes and data electrodes, characterized in that the display device comprises, between the data electrode and the pixel, in series with a field effect transistor (11) of the first type, at least a second field effect transistor (12) of a second, opposite type, the gate electrode of one of the field effect transistors being connected to a selection electrode(s) (5).

2. A display device as claimed in claim 1, characterized in that the gate electrode (13) of the first field effect transistor (11) of the first type is connected to the selection electrode (5).

3. A display device as claimed in claim 2, characterized in that the gate electrode (14) of the second field effect transistor (12) of the second type is connected to an extra selection electrode (4).

4. A display device as claimed in claim 1, characterized in that the gate electrode (14) of the second field effect transistor (12) of the second type is connected to a data electrode (6, 24).

5. A display device as claimed in claim 3, characterized in that the display device comprises drive means (3, 7, 35, 36) for supplying selection pulses to the gate electrodes of the field effect transistors.

6. A display device as claimed in claim 5, characterized in that the selection pulses are simultaneously supplied to the gate electrodes of the field effect transistors.

7. A display device as claimed in claim 4, characterized in that the display device comprises drive means (3, 7, 35, 36) for the supply of selection pulses to the gate electrode of the first field effect transistor (11) and for the conditioned supply of selection pulses to the gate electrode of the second field effect transistor (12).

8. A display device as claimed in claim 7, characterized in that the selection pulses for the first field effect transistor differ in time duration from those for the second field effect transistor.

9. A display device as claimed in claim 7 or 8, characterized in that the drive means comprise means for temporarily suppressing the selection pulses of at least one of the field effect transistors.

10. A display device as claimed in claim 8 or 9, characterized in that the selection pulses are supplied at a different frequency to the gate electrodes of the field effect transistors.

11. A display device as claimed in claim 2, characterized in that the gate electrode of the second field effect transistor of the second type is connected to a data electrode.

12. A display device as claimed in claim 1, characterized in that the display device comprises a capacitor (15), an electrode of which is connected to an electrode of the pixel.

13. A display device as claimed in claim 1, characterized in that the pixel comprises at least a layer of liquid crystal material between two picture electrodes.

14. A display device as claimed in claim 13, characterized in that the display device comprises a capacitor (15) between the electrode (19) of the pixel and an electrode (16) connected to a terminal of a power supply voltage (17).

15. A display device as claimed in claim 1, characterized in that the display device comprises a capacitor (31), an electrode of which is connected to the common point of the field effect transistor of the first type and the field effect transistor of the second type.

16. A display device as claimed in claim 15, characterized in that the display device comprises a plurality of field effect transistors of the first type between the selection electrode and a plurality of capacitances associated with each field effect transistor of the first type.

17. A display device as claimed in claim 16, characterized in that the selection electrode is connected to a bias voltage.

18. A display device as claimed in claim 17, characterized in that the bias voltage is variable.

19. A display device as claimed in claim 1, characterized in that the pixel comprises at least a luminescent element (25) in series with an adjusting transistor (26).