Input/output device and driving method thereof

• US 8,605,059 B2
• Filed: 06/22/2011
• Issued: 12/10/2013
• Est. Priority Date: 07/02/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kurokawa, Yoshiyuki, Ikeda, Takayuki
• Primary Examiner(s): Cheng, Joe H
• Application Number:
  US13/166,041
• Publication Number:
  US 20120001874A1
• Time in Patent Office: 902 Days
• Field of Search: 345/179, 345173-175, 178/18.09, 178/18.11
• US Class Current: 345/175
• CPC Class Codes: G06F 1/3206 Monitoring of events, devices or parameters that trigger a change in power modality
• CPC Class Codes: G06F 1/3262 Power saving in digitizer or tablet
• CPC Class Codes: G06F 1/3287 by switching off individual functional units in the computer system
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/042 by opto-electronic means
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

An object is to reduce power consumption. An input/output device including: a display selection signal output circuit outputting a display selection signal during a first display mode and stopping outputting the display selection signal during a second display mode; a photodetection reset signal output circuit outputting N (N is a natural number) photodetection reset signals during a first photodetection mode and outputting M (M is a natural number smaller than N) photodetection reset signals during a second photodetection mode; an output selection signal output circuit outputting N output selection signals during the first photodetection mode and outputting M output selection signals during the second photodetection mode; and a photodetector circuit being reset in accordance with a photodetection reset signal, generating data according to an intensity of light entering the photodetector circuit subsequently, and outputting the data as a data signal in accordance with the output selection signal.

Claims

1. A method for driving an input/output device comprising:

a display circuit; and

a photodetector circuit,

the method for driving comprising the steps of;

supplying a display signal to the display circuit during a first display mode;

not supplying the display signal to the display circuit during a second display mode;

supplying a display data signal to the display circuit during the first display mode;

supplying N (N is a natural number of 2 or more) reset signals to the photodetector circuit during a first photodetection mode;

supplying M (M is a natural number smaller than N) reset signals to the photodetector circuit during a second photodetection mode;

supplying N select signals to the photodetector circuit during the first photodetection mode;

supplying M select signals to the photodetector circuit during the second photodetection mode;

performing a reset operation in accordance with the reset signals by the photodetector circuit;

performing a photocurrent detecting operation to generate data according to an intensity of light entering the photodetector circuit after the reset operation by the photodetector circuit; and

performing a selecting operation to output the data as a data signal in accordance with the select signals by the photodetector circuit.

2. The method for driving the input/output device according to claim 1, further comprising the step of:

not supplying the display data signal to the display circuit during the second display mode.

3. The method for driving the input/output device according to claim 2,

wherein the input/output device comprises a first transistor, and

wherein the first transistor comprises an oxide semiconductor.

4. The method for driving the input/output device according to claim 3,

wherein the photodetector circuit comprises a photoelectric transducer and a second transistor.

5. The method for driving the input/output device according to claim 4,

wherein the second transistor comprises an oxide semiconductor.

6. The method for driving the input/output device according to claim 3,

wherein the photodetector circuit comprises pixels arranged in matrix,

the method for driving comprises the steps of:

performing the reset operation in each of pixels sequentially;

performing the photocurrent detecting operation in each of the pixels sequentially; and

performing the selecting operation in each of the pixels sequentially,

wherein each of the pixels comprises a photoelectric transducer and a second transistor.

7. The method for driving the input/output device according to claim 6,

wherein the second transistor comprises an oxide semiconductor.

8. The method for driving the input/output device according to claim 3,

wherein the photodetector circuit comprises pixels arranged in matrix,

the method for driving comprises the steps of:

performing the reset operation in each of pixels simultaneously;

performing the photocurrent detecting operation in each of the pixels simultaneously; and

performing the selecting operation in each of the pixels sequentially,

wherein each of the pixels comprises a photoelectric transducer and a second transistor.

9. The method for driving the input/output device according to claim 8,

wherein the second transistor comprises an oxide semiconductor.

10. A method for driving an input/output device comprising:

a display circuit;

a photodetector circuit;

a display driver circuit; and

a photodetector driver circuit,

the method for driving comprising the steps of;

supplying a display signal from the display driver circuit to the display circuit during a first display mode;

not supplying the display signal from the display driver circuit to the display circuit during a second display mode;

supplying a display data signal to the display circuit during the first display mode;

supplying N (N is a natural number of 2 or more) reset signals from the photodetector driver circuit to the photodetector circuit during a first photodetection mode;

supplying M (M is a natural number smaller than N) reset signals from the photodetector driver circuit to the photodetector circuit during a second photodetection mode;

supplying N select signals from the photodetector driver circuit to the photodetector circuit during the first photodetection mode;

supplying M select signals from the photodetector driver circuit to the photodetector circuit during the second photodetection mode;

performing a reset operation in accordance with the reset signals by the photodetector circuit;

performing a photocurrent detecting operation to generate data according to an intensity of light entering the photodetector circuit after the reset operation by the photodetector circuit; and

performing a selecting operation to output the data as a data signal in accordance with the select signals by the photodetector circuit.

11. The method for driving the input/output device according to claim 10, further comprising the step of:

not supplying the display data signal to the display circuit during the second display mode.

12. The method for driving the input/output device according to claim 11,

wherein the photodetector circuit comprises a photoelectric transducer and a second transistor.

13. The method for driving the input/output device according to claim 12,

wherein the second transistor comprises an oxide semiconductor.

14. The method for driving the input/output device according to claim 11,

wherein the photodetector circuit comprises pixels arranged in matrix,

the method for driving comprises the steps of:

performing the reset operation in each of pixels sequentially;

performing the photocurrent detecting operation in each of the pixels sequentially; and

performing the selecting operation in each of the pixels sequentially,

wherein each of the pixels comprises a photoelectric transducer and a second transistor.

15. The method for driving the input/output device according to claim 14,

wherein the second transistor comprises an oxide semiconductor.

16. The method for driving the input/output device according to claim 11,

wherein the photodetector circuit comprises pixels arranged in matrix,

the method for driving comprises the steps of:

performing the reset operation in each of pixels simultaneously;

performing the photocurrent detecting operation in each of the pixels simultaneously; and

performing the selecting operation in each of the pixels sequentially,

wherein each of the pixels comprises a photoelectric transducer and a second transistor.

17. The method for driving the input/output device according to claim 16,

wherein the second transistor comprises an oxide semiconductor.

18. An input/output device comprising:

a display selection signal output circuit configured to perform supply of a display selection signal during a first display mode and configured to stop supply of the display selection signal during a second display mode;

a display data signal output circuit configured to receive an image signal and configured to generate a display data signal on a basis of the image signal;

a photodetection reset signal output circuit configured to generate N (N is a natural number of 2 or more) photodetection reset signals during a first photodetection mode and configured to generate M (M is a natural number smaller than N) photodetection reset signals during a second photodetection mode;

an output selection signal output circuit configured to generate N output selection signals during the first photodetection mode and configured to generate M output selection signals during the second photodetection mode; and

a photodetector circuit configured to receive the photodetection reset signal and the output selection signal, configured to perform reset in accordance with the photodetection reset signal, configured to generate data according to an intensity of light entering the photodetector circuit subsequently, and configured to generate the data as a data signal in accordance with the output selection signal.

19. The input/output device according to claim 18, wherein the output selection signal output circuit and the photodetection reset signal output circuit each comprise:

a shift register configured to generate L (L is a natural number of 2 or more) first pulse signals; and

L logic circuits,

wherein one of the L logic circuits is configured to receive a first pulse signal and a second pulse signal and configured to generate the output selection signal,

wherein the first pulse signal is one of the L first pulse signals,

wherein the second pulse signal is one of Z (Z is a natural number of 2 or more and L or less) pulse control signals, and

wherein the output selection signal is determined in accordance with the first pulse signal and the second pulse signal.

20. A method for driving an input/output device comprising:

a display selection signal output circuit;

a pixel data signal output circuit;

a photodetection selection signal output circuit;

a photodetector circuit; and

a reading circuit,

the method for driving comprising the steps of;

performing supply of a photodetection reset signal to the photodetector circuit;

performing reset of the photodetector circuit in accordance with the photodetection reset signal every unit period;

generating data in the photodetector circuit according to an intensity of light entering the photodetector circuit subsequently after the reset of the photodetector circuit;

generating N (N is a natural number of 2 or more) photodetection selection signals from the photodetection selection signal output circuit during a first photodetection mode;

outputting the data as a first data signal from the photodetector circuit in accordance with one of the N photodetection selection signals;

reading the first data signal from the photodetector circuit sequentially by the reading circuit;

generating M (M is a natural number smaller than N) photodetection selection signals from the photodetection selection signal output circuit during a second photodetection mode;

outputting the data as a second data signal from the photodetector circuit in accordance with one of the M photodetection selection signals;

reading the second data signal from the photodetector circuit sequentially by the reading circuit;

generating a display selection signal from the display selection signal output circuit during a first display mode and the first photodetection mode;

generating the display selection signal from the display selection signal output circuit during the first display mode and the second photodetection mode;

stopping generation of the display selection signal from the display selection signal output circuit during a second display mode and the first photodetection mode;

stopping generation of the display selection signal from the display selection signal output circuit during the second display mode and the second photodetection mode;

switching the input/output device from the second photodetection mode to the first photodetection mode in accordance with a value of data generated by the photodetector circuit in successive periods of the second photodetection mode; and

switching the input/output device from the second display mode to the first display mode in accordance with the value of the data generated by the photodetector circuit in successive periods of the first photodetection mode.