Display panel with photo sensor and display device using the same
A display panel comprises a plurality of pixels into which pixel data of an input image is written; a plurality of data lines connected to the plurality of pixels; a plurality of photo sensors configured to sense light; a plurality of read-out lines connected to the plurality of photo sensors; and a plurality of gate lines connected to the pixels and the photo sensors, wherein the plurality of photo sensors comprises at least one first photo sensor to which a first bias voltage is supplied and at least one second photo sensor to which a second bias voltage different from the first bias voltage is supplied.
1. A display panel comprising:
a plurality of pixels into which pixel data of an input image is written;
a plurality of data lines connected to the plurality of pixels;
a plurality of photo sensors configured to sense light;
a plurality of read-out lines connected to the plurality of photo sensors; and
a plurality of gate lines connected to the pixels and the photo sensors,
wherein the plurality of photo sensors comprises at least one first photo sensor to which a first bias voltage is supplied and at least one second photo sensor to which a second bias voltage different from the first bias voltage is supplied, and
wherein the plurality of pixels are driven during a pixel driving time interval, and the plurality of photo sensors are driven during a photo sensor driving time interval different from the pixel driving time interval, the pixel driving time interval and photo sensor driving time interval included in one frame period,
wherein the first photo sensor is connected to a first read-out line, and the second photo sensor is connected to a second read-out line,
wherein the first photo sensor and the second photo sensor are adjacent to each other in a horizontal direction, and
wherein the first photo sensor and the second photo sensor are alternately connected to the first read-out line in at least 2-dot intervals.
2. The display panel of claim 1 , wherein the first photo sensor and the second photo sensor are alternately connected to the second read-out line in the at least 2-dot intervals.
3. The display panel of claim 1 , wherein the first and second photo sensors that are supplied with a bias voltage are switched between the first bias voltage and the second bias voltage.
4. The display panel of claim 1 , wherein each of the photo sensors comprises:
a first transistor in an OFF state to which the first bias voltage or the second bias voltage is applied;
a second transistor turned on according to a gate on voltage applied from the plurality of gate lines; and
a capacitor connected to a node between the first transistor and the second transistor,
wherein +V>Vref>−V>Voff where +V is the first bias voltage, −V is the second bias voltage, Vref is a reference voltage between the first bias voltage and the second bias voltage, and Voff is a gate voltage of the first transistor.
5. The display panel of claim 4 , wherein the capacitor comprises:
a first electrode connected to the node between the first transistor and the second transistor; and
a second electrode to which the Voff is applied.
6. The display panel of claim 1 , further comprising a read-out unit connected to the plurality of read-out lines and amplifying signals from the plurality of photo sensors to convert the amplified signals into digital data.
7. The display panel of claim 6 , wherein the read-out unit comprises:
a differential amplifier amplifying a differential signal voltage of a first photo sensor signal and a second photo sensor signal;
a sample and holder sampling an output voltage from the differential amplifier; and
an analog-to-digital converter (ADC) converting a voltage from the sample and holder into the digital data.
8. The display panel of claim 7 , wherein the differential amplifier comprises:
an operational amplifier including an inverting input terminal, a non-inverting input terminal, an inverting output terminal, and a non-inverting output terminal;
a capacitor connected between the inverting input terminal and the non-inverting output terminal;
a reset switch element connected between the inverting input terminal and the non-inverting output terminal;
a capacitor connected between the non-inverting input terminal and the inverting output terminal; and
a reset switch element connected between the non-inverting input terminal and the inverting output terminal.
9. The display panel of claim 8 , wherein the inverting input terminal of the differential amplifier is connected to a first read-out line,
the non-inverting input terminal of the differential amplifier is connected to a second read-out line,
the first read-out line is connected to the first photo sensor,
the second read-out line is connected to the second photo sensor, and
the first photo sensor connected to the first read-out line and the second photo sensor connected to the second read-out line neighbor each other in a horizontal direction.
10. The display panel of claim 8 , wherein the inverting input terminal of the differential amplifier is connected to a first read-out line,
the non-inverting input terminal of the differential amplifier is connected to a second read-out line,
the first photo sensor is connected to the first read-out line,
the second photo sensor is connected to the second read-out line, and
the first photo sensor and the second photo sensor neighbor each other in a horizontal direction.
11. The display panel of claim 8 , wherein the inverting input terminal of the differential amplifier is connected to a first read-out line,
the non-inverting input terminal of the differential amplifier is connected to a second read-out line,
a predetermined number of the first photo sensor and a predetermined number of the second photo sensor are alternately connected to the first read-outline at 3-dot intervals, and
the first photo sensor and the second photo sensor neighbor each other in a horizontal direction.
12. A display device comprising:
a display panel including a plurality of pixels where pixel data of an input image is written, a plurality of data lines connected to the plurality of pixels, a plurality of photo sensors sensing light, a plurality of read-out lines connected to the plurality of photo sensors, and a plurality of gate lines connected to the plurality of pixels and the plurality of photo sensors;
a display panel driver writing the pixel data of the input image into the pixels; and
a read-out unit connected to the plurality of read-out lines and amplifying signals from the plurality of photo sensors to convert the amplified signals into digital data,
wherein the photo sensors comprise:
at least one first photo sensor supplied with a first bias voltage; and
at least one second photo sensor supplied with a second bias voltage that is different from the first bias voltage,
wherein the plurality of pixels are driven during a pixel driving time interval, and the plurality of photo sensors are driven during a photo sensor driving time interval different from the pixel driving time interval, the pixel driving time interval and photo sensor driving time interval obtained included in one frame period,
wherein the first photo sensor is connected to a first read-out line, and the second photo sensor is connected to a second read-out line,
wherein the first photo sensor and the second photo sensor are adjacent to each other in a horizontal direction, and
wherein the first photo sensor and the second photo sensor are alternately connected to the first read-out line in at least 2-dot intervals.
13. The display device of claim 12 , wherein the read-out unit comprises:
a differential amplifier amplifying a differential signal voltage of a first photo sensor signal and a second photo sensor signal;
a sample and holder sampling an output voltage from the differential amplifier; and
an analog-to-digital converter (ADC) converting a voltage from the sample and holder into the digital data.
14. The display device of claim 13 , wherein the differential amplifier comprises:
an operational amplifier including an inverting input terminal, a non-inverting input terminal, an inverting output terminal, and a non-inverting output terminal;
a capacitor connected between the inverting input terminal and the non-inverting output terminal;
a reset switch element connected between the inverting input terminal and the non-inverting output terminal;
a capacitor connected between the non-inverting input terminal and the inverting output terminal; and
a reset switch element connected between the non-inverting input terminal and the inverting output terminal.
15. The display device of claim 14 , wherein the inverting input terminal of the differential amplifier is connected to a first read-out line,
the non-inverting input terminal of the differential amplifier is connected to a second read-out line,
the first read-out line is connected to the first photo sensor,
the second read-out line is connected to the second photo sensor, and
the first photo sensor connected to the first read-out line and the second photo sensor connected to the second read-out line neighbor each other in a horizontal direction.
16. The display device of claim 14 , wherein the inverting input terminal of the differential amplifier is connected to a first read-out line,
the non-inverting input terminal of the differential amplifier is connected to a second read-out line,
the first photo sensor is connected to the first read-out line,
the second photo sensor is connected to the second read-out line, and
the first photo sensor and the second photo sensor neighbor each other in a horizontal direction.
17. The display device of claim 14 , wherein the inverting input terminal of the differential amplifier is connected to a first read-out line,
the non-inverting input terminal of the differential amplifier is connected to a second read-out line,
a predetermined number of the first photo sensor and a predetermined number of the second photo sensor are alternately connected to the first read-outline at 3-dot intervals, and
the first photo sensor and the second photo sensor neighbor each other in a horizontal direction.
18. The display device of claim 12 , wherein the read-out unit comprises:
a first differential amplifier amplifying a differential signal voltage of a first photo sensor signal and a second photo sensor signal to generate an inverted output voltage and a non-inverted output voltage;
a second differential amplifier amplifying a differential signal voltage between the inverted output voltage and the non-inverted output voltage to generate a single output voltage;
a sample and holder sampling an output voltage from the second differential amplifier; and
an analog-to-digital converter (ADC) converting a voltage from the sample and holder into the digital data.
19. The display device of claim 12 , wherein each of the photo sensors comprises:
a first transistor in an OFF state to which the first bias voltage or the second bias voltage is applied;
a second transistor turned on according to a gate on voltage applied from the gate line; and
a capacitor connected to a node between the first transistor and the second transistor,
wherein +V>Vref>−V>Voff where +V is the first bias voltage, −V is the second bias voltage, Vref is a reference voltage between the first bias voltage and the second bias voltage, and Voff is a gate voltage of the first transistor.
20. The display panel of claim 12 , wherein the first photo sensor and the second photo sensor are alternately connected to the second read-out line in the at least 2-dot intervals.