DISPLAY DEVICE WITH TOUCH SENSOR

• US 20130057518A1
• Filed: 05/19/2011
• Published: 03/07/2013
• Est. Priority Date: 05/20/2010
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Sugita, Yasuhiro, Tanaka, Kohei, Usukura, Naru, Nemoto, Tadashi, Katoh, Hiromi
• Granted Patent: US 9,041,699 B2
• Time in Patent Office: Days
• US Class Current: 345/175
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/042 by opto-electronic means
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: H01L 27/14621 Colour filter arrangements
• CPC Class Codes: H01L 27/14645 Colour imagers

Abstract

Provided is a display device that has a photodetection element in a pixel and can automatically correct a photosensor signal during operation, while resolving offset error with respect to the true black level or white level. As operation modes, a sensor row driver (5) has: (a) a sensor drive mode in which a sensor drive signal of a first pattern is supplied, and a photosensor signal that corresponds to the amount of light received by the photosensor is output to a signal processing circuit (8), and (b) a correction data acquisition mode in which a sensor drive signal of a second pattern that is different from the first pattern is supplied, and a correction photosensor signal level that corresponds to the case where the photosensor detected a black level or a white level is acquired. The photosensor signal levels obtained in the two modes while the ambient environment is controlled to a predetermined condition are stored in a memory. The signal processing circuit (8) corrects the photosensor signal in the sensor drive mode using the correction photosensor signal level that was corrected using the data for resolving offset.

Claims

1. A display device provided with an active matrix substrate, the display device comprising:

a photosensor provided in a pixel region of the active matrix substrate;

sensor drive wiring connected to the photosensor;

a sensor driver circuit that supplies a sensor drive signal to the photosensor via the sensor drive wiring;

an amplifier circuit that amplifies sensor output that was read out from the photosensor in accordance with the sensor drive signal, and outputs the sensor output as a photosensor signal; and

a signal processing circuit that processes the photosensor signal that was output from the amplifier circuit,

wherein operation modes of the sensor driver circuit include at least

a sensor drive mode in which a sensor drive signal of a first pattern is supplied to the photosensor, and thus a photosensor signal that corresponds to the amount of light received by the photosensor is output to the signal processing circuit, and

a correction data acquisition mode in which a sensor drive signal of a second pattern that is different from the first pattern is supplied to the photosensor, and thus a correction photosensor signal level that corresponds to a case where the photosensor detected a black level or a white level is acquired,

the display device further comprises a memory that stores, as data for resolving offset in the correction photosensor signal level, a photosensor signal level that was obtained by driving the photosensor in each of the sensor drive mode and the correction data acquisition mode in an ambient environment that is controlled to a predetermined condition, and

the signal processing circuit corrects the photosensor signal in the sensor drive mode using the correction photosensor signal level that was corrected using the data for resolving offset that was read out from the memory.

2. The display device according to claim 1,

wherein the sensor drive wiring includes reset signal wiring that is connected to the photosensor and readout signal wiring that is connected to the photosensor,

the sensor drive signal includes a reset signal that is supplied to the photosensor via the reset signal wiring and a readout signal that is supplied to the photosensor via the readout signal wiring, and

in the sensor drive mode, the sensor driver circuit supplies the photosensor with the reset signal, and then with the readout signal after a predetermined time period has elapsed, and thus a photosensor signal that corresponds to the amount of light received by the photosensor in the predetermined time period is output to the signal processing circuit.

3. The display device according to claim 2,

wherein the correction data acquisition mode includes a first correction data acquisition mode in which the readout signal is supplied from the sensor driver circuit to the photosensor at a time that is after the start of the supply of the reset signal and before the end of the supply of the reset signal, and thus a first correction photosensor signal level B that corresponds to a case where the photosensor detected a black level is acquired, and

in an ambient environment that is controlled to a predetermined condition, letting B_1st.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the sensor drive mode, and B_2nd.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the first correction data acquisition mode,

the signal processing circuit obtains a corrected photosensor signal R′

from a photosensor signal R in the sensor drive mode as follows;

R′

=R−

{B−

(B_2nd.ini−

B_1st.ini)}.

4. The display device according to claim 2,

wherein the correction data acquisition mode includes a second correction data acquisition mode in which the sensor driver circuit supplies a readout signal whose amplitude is zero, and thus a second correction photosensor signal level W that corresponds to a case where the photosensor detected a white level is acquired, and

in an ambient environment that is controlled to a predetermined condition, letting W_1st.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the sensor drive mode, W_3rd.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the second correction data acquisition mode, and L be the number of photosensor signal levels, and in an ambient environment that is controlled to a predetermined condition, letting B_1st.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the sensor drive mode,

the signal processing circuit obtains a corrected photosensor signal R′

from a photosensor signal R in the sensor drive mode as follows;

R′

=L×

R/{W−

(W_3rd.ini−

W_1st.ini)−

B_1st.ini}.

5. The display device according to claim 2,

wherein the correction data acquisition mode includes a first correction data acquisition mode in which the readout signal is supplied from the sensor driver circuit to the photosensor at a time that is after the start of the supply of the reset signal and before the end of the supply of the reset signal, and thus a first correction photosensor signal level B that corresponds to a case where the photosensor detected a black level is acquired, and a second correction data acquisition mode in which the sensor driver circuit supplies a readout signal whose amplitude is zero, and thus a second correction photosensor signal level W that corresponds to a case where the photosensor detected a white level is acquired, and

in an ambient environment that is controlled to a predetermined condition, letting B_1st.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the sensor drive mode, and B_2nd.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the first correction data acquisition mode, and in an ambient environment that is controlled to a predetermined condition, letting B_1st.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the sensor drive mode, W_3rd.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the second correction data acquisition mode, and L be the number of photosensor signal levels,

the signal processing circuit obtains a corrected photosensor signal R′

from a photosensor signal R in the sensor drive mode as follows;

6. The display device according to claim 2,

wherein the correction data acquisition mode includes a first correction data acquisition mode in which the readout signal is supplied from the sensor driver circuit to the photosensor at a time that is after the start of the supply of the reset signal and after the end of the supply of the reset signal, and thus a first correction photosensor signal level B that corresponds to a case where the photosensor detected a black level is acquired, and

in an ambient environment that is controlled to a predetermined condition, letting B_1st.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the sensor drive mode, and B_2nd.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the first correction data acquisition mode,

the signal processing circuit obtains a corrected photosensor signal R′

from a photosensor signal R in the sensor drive mode as follows;

R′

=R−

{B−

(B_2nd.ini−

B_1st.ini)}.

7. The display device according to claim 2,

wherein the correction data acquisition mode includes a second correction data acquisition mode in which the sensor driver circuit supplies a readout signal whose amplitude is zero, and thus a second correction photosensor signal level W that corresponds to a case where the photosensor detected a white level is acquired, and

in an ambient environment that is controlled to a predetermined condition, letting B_1st.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the sensor drive mode, and in an ambient environment that is controlled to a predetermined condition, letting W_1st.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the sensor drive mode, W_3rd.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the second correction data acquisition mode, and L be the number of photosensor signal levels,

the signal processing circuit obtains a corrected photosensor signal R′

from a photosensor signal R in the sensor drive mode as follows;

R′

=L×

R/{W−

(W_3rd.ini−

W_1st.ini)−

B_1st.ini}.

8. The display device according to claim 2,

wherein the correction data acquisition mode includes a first correction data acquisition mode in which the readout signal is supplied from the sensor driver circuit to the photosensor at a time that is after the start of the supply of the reset signal and after the end of the supply of the reset signal, and thus a first correction photosensor signal level B that corresponds to a case where the photosensor detected a black level is acquired, and a second correction data acquisition mode in which the sensor driver circuit supplies a readout signal whose amplitude is zero, and thus a second correction photosensor signal level W that corresponds to a case where the photosensor detected a white level is acquired, and

in an ambient environment that is controlled to a predetermined condition, letting B_1st.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the sensor drive mode, and B_2nd.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the first correction data acquisition mode, and

in an ambient environment that is controlled to a predetermined condition, letting W_1st.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the sensor drive mode, W_3rd.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the second correction data acquisition mode, and L be the number of photosensor signal levels,

the signal processing circuit obtains a corrected photosensor signal R′

from a photosensor signal R in the sensor drive mode as follows;

9. The display device according to claim 2,

wherein the correction data acquisition mode includes a second correction data acquisition mode in which the sensor driver circuit supplies, in synchronization with the reset signal, a readout signal whose amplitude is Δ

V_RWS.WHITE for reading out sensor output that corresponds to a state in which the amount of shift in capacitance output of the photosensor is saturated, and thus a second correction photosensor signal level W that corresponds to a case where the photosensor detected a white level is acquired, and

in an ambient environment that is controlled to a predetermined condition, letting W_1st.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the sensor drive mode, W_3rd.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the second correction data acquisition mode, and L be the number of photosensor signal levels, and in an ambient environment that is controlled to a predetermined condition, letting B_1st.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the sensor drive mode,

the signal processing circuit obtains a corrected photosensor signal R′

from a photosensor signal R in the sensor drive mode as follows;

R′

=L×

R/{W−

(W_3rd.ini−

W_1st.ini)−

B_1st.ini}.

10. The display device according to claim 2,

wherein the correction data acquisition mode includes a first correction data acquisition mode in which the readout signal is supplied from the sensor driver circuit to the photosensor at a time that is after the start of the supply of the reset signal and after the end of the supply of the reset signal, and thus a first correction photosensor signal level B that corresponds to a case where the photosensor detected a black level is acquired, and a second correction data acquisition mode in which the sensor driver circuit supplies, in synchronization with the reset signal, a readout signal whose amplitude is Δ

V_RWS.WHITE for reading out sensor output that corresponds to a state in which the amount of shift in capacitance output of the photosensor is saturated, and thus a second correction photosensor signal level W that corresponds to a case where the photosensor detected a white level is acquired, and

in an ambient environment that is controlled to a predetermined condition, letting B_1st.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the sensor drive mode, and B_2nd.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the first correction data acquisition mode,

in an ambient environment that is controlled to a predetermined condition, letting W_1st.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the sensor drive mode, W_3rd.ini be the photosensor signal level stored in the memory that was obtained by driving the photosensor in the second correction data acquisition mode, and L be the number of photosensor signal levels,

the signal processing circuit obtains a corrected photosensor signal R′

from a photosensor signal R in the sensor drive mode as follows;

11. The display device according to claim 9,

wherein the photosensor includes one photodiode and a capacitor that is connected to a cathode of the photodiode, and

the amplitude Δ

V_RWS.WHITE of the readout signal is obtained by the following expression;

12. The display device according to claim 1, wherein the photosensor has one sensor switching element.

13. The display device according to claim 1, further comprising:

a common substrate opposing the active matrix substrate; and

liquid crystal sandwiched between the active matrix substrate and the common substrate.