Input-output device and method for driving input-output device

• US 9,489,088 B2
• Filed: 06/15/2011
• Issued: 11/08/2016
• Est. Priority Date: 06/16/2010
• 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): FRY, MATTHEW A
• Application Number:
  US13/160,903
• Publication Number:
  US 20110310063A1
• Time in Patent Office: 1,973 Days
• Field of Search: 345/175, 345/173, 345/102, 345/73, 257/292
• US Class Current: 1/1
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: H05B 47/11 by determining the brightness or colour temperature of ambient light
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

Accuracy of photodetection is improved. An input-output device includes a light unit including Z (Z is a natural number of 3 or more) first light-emitting diodes that emit light with a wavelength in a visible light range and a second light-emitting diode that emits light with a wavelength in an infrared range; a display circuit that is supplied with a display selection signal, supplied with a display data signal in accordance with the display selection signal, and set to be in a display state based on data of the input display data signal; and Y (Y is a natural number) photodetectors including a filter for absorbing light with a wavelength in a visible light range, supplied with a photodetection control signal is input, and generating data based on the illuminance of incident light in accordance with the input photodetection control signal.

Claims

1. An input-output device comprising:

a light unit comprising Z (Z is a natural number of 3 or more) first light-emitting diodes emitting light with a wavelength in a visible light range and a second light-emitting diode emitting light with a wavelength in an infrared range;

X (X is a natural number) display circuits overlapping with the light unit; and

a plurality of photodetectors overlapping with the light unit,

wherein the plurality of photodetectors include a filter for absorbing light with a wavelength in a visible light range,

wherein each of the plurality of photodetectors comprises a first transistor, a second transistor and a photoelectric conversion element,

wherein one of a source electrode and a drain electrode of the first transistor is electrically connected to the photoelectric conversion element,

wherein a gate of the second transistor is electrically connected to the other of the source electrode and the drain electrode of the first transistor,

wherein the Z first light-emitting diodes configured to emit light of different colors,

wherein the Z first light-emitting diodes configured to emit light sequentially in a first frame period,

wherein the second light-emitting diode is configured not to emit light during a first period in which a first light-emitting diode of the Z first light-emitting diodes emits light and configured to emit light during a second period in which second to Z-th light-emitting diodes of the Z first light emitting diodes emit light sequentially, in the first frame period,

wherein the X display circuits are configured to receive a display selection signal, receive a display data signal in accordance with the display selection signal, and set to be in a display state in accordance with data of the display data signal, and

wherein the plurality of photodetectors are configured to perform detection by a global shutter method in which the plurality of photodetectors receive the same photodetection control signal, and generate data based on illuminance of incident light in accordance with the photodetection control signal during the second period of the first frame period.

2. The input-output device according to claim 1,

wherein the photoelectric conversion element comprises a first conductive layer, a semiconductor layer over the first conductive layer and a second conductive layer over the semiconductor layer,

wherein the semiconductor layer comprises a silicon layer,

wherein one of the source electrode and the drain electrode of the first transistor is electrically connected to the second conductive layer,

wherein the first transistor and the second transistor are field effect transistors,

wherein the photoelectric conversion element is configured to supply current between the first conductive layer and the second conductive layer in accordance with illuminance of incident light,

wherein the photodetection control signal is input to a gate of the first transistor, and

wherein the second transistor is configured to output data based on the illuminance of the incident light as a data signal from a source electrode or a drain electrode.

3. The input-output device according to claim 2,

wherein the first transistor comprises an oxide semiconductor layer and the source electrode and the drain electrode over and in contact with the oxide semiconductor layer,

wherein the oxide semiconductor layer comprises an intrinsic or substantially intrinsic oxide semiconductor, and

wherein the first transistor includes the oxide semiconductor layer which has a carrier concentration of lower than 1×

10¹⁴/cm³.

4. The input-output device according to claim 1, further comprising:

a reading circuit configured to read data based on the illuminance of the incident light supplied from the plurality of photodetectors; and

a data processing circuit configured to generate difference data between two pieces of data based on the illuminance of the incident light read by the reading circuit.

11. The input-output device according to claim 2,

wherein the source electrode, the drain electrode and the first conductive layer are over and in contact with a first insulating layer, and

wherein a second insulating layer is provided so as to be in contact with an oxide semiconductor layer and the first conductive layer.

15. The input-output device according to claim 1, wherein an off-state current of the first transistor per micrometer of channel width is between 100 yA and 10⁻

30A.

5. An input-output device comprising:

a first light unit comprising Z (Z is a natural number of 3 or more) first light-emitting diodes emitting light with a wavelength in a visible light range;

a second light unit comprising a second light-emitting diode emitting light with a wavelength in an infrared range;

X (X is a natural number) display circuits provided between the first light unit and the second light unit; and

a plurality of photodetectors provided between the first light unit and the second light unit,

wherein the plurality of photodetectors include a filter for absorbing light with a wavelength in a visible light range,

wherein each of the plurality of photodetectors comprises a first transistor, a second transistor and a photoelectric conversion element,

wherein one of a source electrode and a drain electrode of the first transistor is electrically connected to the photoelectric conversion element,

wherein a gate of the second transistor is electrically connected to the other of the source electrode and the drain electrode of the first transistor,

wherein the Z first light-emitting diodes configured to emit light of different colors,

wherein the Z first light-emitting diodes configured to emit light sequentially in a first frame period,

wherein the second light-emitting diode is configured not to emit light during a first period in which a first light-emitting diode of the Z first light-emitting diodes emits light and configured to emit light during a second period in which second to Z-th light-emitting diodes of the Z first light emitting diodes emit light sequentially, in the first frame period,

wherein the X display circuits are configured to receive a display selection signal, receive a display data signal in accordance with the display selection signal, and set to be in a display state in accordance with data of the display data signal, and

wherein the plurality of photodetectors are configured to perform detection by a global shutter method in which the plurality of photodetectors receive the same photodetection control signal, and generate data based on illuminance of incident light in accordance with the photodetection control signal during the second period of the first frame period.

6. The input-output device according to claim 5,

wherein the photoelectric conversion element comprises a first conductive layer, a semiconductor layer over the first conductive layer and a second conductive layer over the semiconductor layer,

wherein the semiconductor layer comprises a silicon layer,

wherein one of the source electrode and the drain electrode of the first transistor is electrically connected to the second conductive layer,

wherein the first transistor and the second transistor are field effect transistors,

wherein the photoelectric conversion element is configured to supply current between the first conductive layer and the second conductive layer in accordance with illuminance of incident light,

wherein the photodetection control signal is input to a gate of the first transistor, and

wherein the second transistor is configured to output data based on the illuminance of the incident light as a data signal from a source electrode or a drain electrode.

7. The input-output device according to claim 6,

wherein the first transistor comprises an oxide semiconductor layer and a source electrode and a drain electrode over and in contact with the oxide semiconductor layer,

wherein the oxide semiconductor layer comprises an intrinsic or substantially intrinsic oxide semiconductor, and

wherein the first transistor includes the oxide semiconductor layer which has a carrier concentration of lower than 1×

10¹⁴/cm³.

8. The input-output device according to claim 5, further comprising:

a reading circuit configured to read data based on the illuminance of the incident light supplied from the plurality of photodetectors; and

a data processing circuit configured to generate difference data between two pieces of data based on the illuminance of the incident light read by the reading circuit.

12. The input-output device according to claim 6,

wherein the source electrode, the drain electrode and the first conductive layer are over and in contact with a first insulating layer, and

wherein a second insulating layer is provided so as to be in contact with an oxide semiconductor layer and the first conductive layer.

16. The input-output device according to claim 5, wherein an off-state current of the first transistor per micrometer of channel width is between 100 yA and 10⁻

30A.

9. A method for driving an input-output device comprising a light unit including Z (Z is a natural number of 3 or more) first light-emitting diodes emitting light with a wavelength in a visible light range and a second light-emitting diode emitting light with a wavelength in an infrared range, X(X is a natural number) display circuits overlapping with the light unit, and a plurality of photodetectors overlapping with the light unit and including a filter for absorbing light with a wavelength in a visible light range, wherein the Z first light-emitting diodes configured to emit light of different colors, and wherein each of the plurality of photodetectors comprises a first transistor, a photoelectric conversion element electrically connected to one of a source electrode or a drain electrode of the first transistor, and a second transistor whose gate is electrically connected to the other of the source electrode and the drain electrode of the first transistor, comprising the steps of:

supplying a display selection signal and a display data signal in accordance with the display selection signal to the X display circuits;

setting the X display circuits in a display state in accordance with data of the display data signal;

emitting light from the Z first light-emitting diodes sequentially in each of a first frame period and a second frame period set by the display selection signal;

supplying the same photodetection control signal to all of the plurality of photodetectors so as to perform a first detection by a global shutter method to generate a plurality of pieces of first data in the first frame period during which the second light-emitting diode emits light;

supplying the same photodetection control signal to all of the plurality of photodetectors so as to perform a second detection by the global shutter method to generate a plurality of pieces of second data in the second frame period during which the second light-emitting diode does not emit light; and

generating third data corresponding to difference between the first data and the second data,

wherein in the first frame period, the second light-emitting diode does not emit light during a first period in which a first light-emitting diode of the Z first light-emitting diodes emits light and emits light during a period in which second to Z-th light-emitting diodes of the Z first light emitting diodes emit light sequentially,

wherein in each of the plurality of photodetectors, the first transistor turns on during the first detection in which the photodetection control signal is supplied to a gate thereof and then turns off so as to keep a gate voltage of the second transistor which is based on the illuminance of light incident on the photodetector during the first detection, and the first data is generated based on the gate voltage of the second transistor, and

wherein in each of the plurality of photodetectors, the first transistor turns on during the second detection in which the photodetection control signal is supplied to the gate thereof and then turns off so as to keep the gate voltage of the second transistor which is based on the illuminance of light incident on the photodetector during the second detection, and the second data is generated based on the gate voltage of the second transistor.

13. The method for driving an input-output device according to claim 9,

wherein the photoelectric conversion element comprises a first conductive layer, a semiconductor layer over the first conductive layer and a second conductive layer over the semiconductor layer,

wherein the source electrode and the drain electrode of the first transistor and the first conductive layer are over and in contact with a first insulating layer,

wherein the first transistor includes an oxide semiconductor layer,

wherein the oxide semiconductor layer comprises an intrinsic or substantially intrinsic oxide semiconductor, and

wherein a second insulating layer is provided so as to be in contact with the oxide semiconductor layer and the first conductive layer.

17. The input-output device according to claim 9, wherein an off-state current of the first transistor per micrometer of channel width is between 100 yA and 10⁻

30A.

10. A method for driving an input-output device comprising a first light unit including Z (Z is a natural number of 3 or more) first light-emitting diodes emitting light with a wavelength in a visible light range, a second light unit including a second light-emitting diode emitting light with a wavelength in an infrared range, X (X is a natural number) display circuits provided between the first light unit and the second light unit, and a plurality of photodetectors provided between the first light unit and the second light unit and including a filter for absorbing light with a wavelength in a visible light range, wherein the Z first light-emitting diodes configured to emit light of different colors, and wherein each of the plurality of photodetectors comprises a first transistor, a photoelectric conversion element electrically connected to one of a source electrode or a drain electrode of the first transistor, and a second transistor whose gate is electrically connected to the other of the source electrode and the drain electrode of the first transistor, comprising the steps of:

supplying a display selection signal and a display data signal in accordance with the display selection signal to the X display circuits;

setting the X display circuits in a display state in accordance with data of the display data signal;

lighting the first light unit by emitting light from the Z first light-emitting diodes sequentially in each of a first frame period and a second frame period set by the display selection signal;

supplying the same photodetection control signal to all of the plurality of photodetectors so as to perform a first detection by a global shutter method to generate a plurality of pieces of first datain the first frame period during which the second light-emitting diode in the second light unit emits light;

supplying the same photodetection control signal to all of the plurality of photodetectors so as to perform a second detection by the global shutter method to generate a plurality of pieces of second data in the second frame period during which the second light-emitting diode in the second light unit does not emit light; and

generating third data corresponding to difference between the first data and the second data,

wherein in the first frame period, the second light-emitting diode does not emit light during a first period in which a first light-emitting diode of the Z first light-emitting diodes emits light and emits light during a period in which second to Z-th light-emitting diodes of the Z first light emitting diodes emit light sequentially,

wherein in each of the plurality of photodetectors, the first transistor turns on during the first detection in which the photodetection control signal is supplied to a gate thereof and then turns off so as to keep a gate voltage of the second transistor which is based on the illuminance of light incident on the photodetector during the first detection, and the first data is generated based on the gate voltage of the second transistor, and

wherein in each of the plurality of photodetectors, the first transistor turns on during the second detection in which the photodetection control signal is supplied to the gate thereof and then turns off so as to keep the gate voltage of the second transistor which is based on the illuminance of light incident on the photodetector during the second detection, and the second data is generated based on the gate voltage of the second transistor.

14. The method for driving an input-output device according to claim 10,

wherein the photoelectric conversion element comprises a first conductive layer, a semiconductor layer over the first conductive layer and a second conductive layer over the semiconductor layer,

wherein the source electrode and the drain electrode of the first transistor and the first conductive layer are over and in contact with a first insulating layer,

wherein the first transistor includes an oxide semiconductor layer,

wherein the oxide semiconductor layer comprises an intrinsic or substantially intrinsic oxide semiconductor, and

wherein a second insulating layer is provided so as to be in contact with the oxide semiconductor layer and the first conductive layer.

18. The input-output device according to claim 10, wherein an off-state current of the first transistor per micrometer of channel width is between 100 yA and 10⁻

30A.