Current output type of semiconductor circuit, source driver for display drive, display device, and current output method

• US 7,561,147 B2
• Filed: 04/28/2004
• Issued: 07/14/2009
• Est. Priority Date: 05/07/2003
• Status: Active Grant

• Current Assignee: Japan Display Central Incorporated (Japan Display Incorporated)
• Original Assignee: Toshiba Matsushita Display Technology (Japan Display Incorporated)
• Inventors: Tsuge, Hitoshi
• Primary Examiner(s): Shalwala; Bipin
• Assistant Examiner(s): Kovalick; Vince E
• Application Number:
  US10/555,642
• Publication Number:
  US 20060279260A1
• Time in Patent Office: 1,903 Days
• Field of Search: 345/87, 345/156, 345/204, 345/205, 345/690, 315/169.3
• US Class Current: 345/204
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/027 Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0223 Compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g. in gate electrodes or on-substrate video signal electrodes
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• CPC Class Codes: G09G 2340/0428 Gradation resolution change
• 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 3/325 the data current flowing through the driving transistor during a setting phase, e.g. by using a switch for connecting the driving transistor to the data driver
• CPC Class Codes: G09G 3/3283 in which the data driver supplies a variable data current for setting the current through, or the voltage across, the light-emitting elements
• CPC Class Codes: H03M 1/68 with conversions of different sensitivity, i.e. one conversion relating to the more significant digital bits and another conversion to the less significant bits
• CPC Class Codes: H03M 1/745 with weighted currents

Abstract

To provide a current output type semiconductor circuit, a drive device for display, a display device, and a current output method that can control an increase in a circuit size to be lower even if the number of output bits of a current driver is increased.

A current output type semiconductor circuit, including first current source groups 241a and 241b, includes first unit transistors of outputting a predetermined current and output lower order N (N is a natural number) bits; and second current source groups 242a, 242b, 242c, 242d, 242e, and 242f that include second unit transistors of outputting a current larger than that of the first unit transistors and output higher order M (M is a natural number, (N+M)≧3) bits.

Claims

1. A current output type semiconductor circuit, comprising:

first current source groups that include a first unit transistor of outputting a predetermined current and output lower order N (N is a natural number) bits; and

second current source groups that include a second unit transistor of outputting a current larger than the predetermined current and output higher order M (M is a natural number, (N+M)≧

3) bits, wherein

a current source group for current increase is provided on a current path through which a current source group of the second current source groups outputs the current for outputting a highest order bit.

2. The current output type semiconductor circuit according to claim 1, wherein, when it is assumed that a channel length of the first unit transistor is L1, a channel width thereof is W1, a channel length of the second unit transistor is L2, and a channel width thereof is W2, L1×

W1<

L2×

W2.

3. The current output type semiconductor circuit according to claim 2, wherein L2×

W2 is a maximum value among values at which fluctuation in an output current of the second unit transistor is equal to or lower than an allowable value of fluctuation in an output current of the first unit transistor.

4. The current output type semiconductor circuit according to claim 1, wherein a trimming circuit for implementation of the current increase is provided.

5. The current output type semiconductor circuit according to claim 1, wherein a control switch for implementation of the current increase is provided.

6. The current output type semiconductor circuit according to claim 5, wherein a memory, which stores a value of a control signal line to determine a state of the control switch, is provided.

7. A current output type semiconductor device, comprising:

a driver that has a drive signal output stage of outputting at least a current signal for driving; and

a control circuit that is constituted separately from the driver and generates at least video signals and command data signals for various controls, wherein

the video signals and the command data signals are outputted from the control circuit via an identical signal line and at staggered times from each other between ON and OFF of a power supply of the control circuit and inputted to the driver.

8. The current output type semiconductor device according to claim 7, comprising a distribution circuit of distributing a signal inputted to the driver into the video signals and the command data signals.

9. A source driver for display device driving, comprising the current output type semiconductor device of claim 7.

10. A display device, comprising the source driver for display device driving of claim 9.

11. A current output type semiconductor device, comprising:

a driver for driving that has a drive signal output stage of outputting at least a current signal for driving; and

a control circuit that is constituted separately from the driver and generates at least video signals and command data signals for various controls, wherein

the video signals are outputted via an identical signal line and at staggered times from each other for each video signal corresponding to each color of the three primary colors between ON and OFF of a power supply of the control circuit.

12. The current output type semiconductor device according to claim 11, comprising a distribution circuit of distributing a signal inputted to the driver into the video signals and the command data signals.

13. A source driver for display device driving, comprising the current output type semiconductor device of claim 11.

14. A display device, comprising the source driver for display device driving of claim 13.

15. A signal input/output method, comprising:

outputting at least a current signal for driving from a driver including a drive signal output stage;

generating at least video signals and command data signals for various controls from a control circuit constituted separately from the driver; and

inputting the video signals and the command data signals to the driver via an identical signal line from the control circuit and at staggered times from each other between ON and OFF of a power supply.

16. A current output type semiconductor circuit comprising:

first current source groups that include a first unit transistor of outputting a predetermined current and output lower order N (N is a natural number) bits; and

second current source groups that include a second unit transistor of outputting a current larger than the predetermined current and output higher order M (m is a natural number, (N+M)≧

3) bits, wherein,

when it is assumed that a channel length of the first unit transistor is L1, a channel width thereof is W1, a channel length of the second unit transistor is L2, and a channel width thereof is W2, L1×

W1<

L2×

W2.

17. The current output type semiconductor circuit according to claim 16, wherein L2×

W2 is a maximum value among values at which fluctuation in an output current of the second unit transistor is equal to or lower than an allowable value of fluctuation in an output current of the first unit transistor.