Display device and electronic device including the same
A display device includes a display panel and a readout circuit. The display panel includes light emitting pixels and light sensing pixels. Each of the light emitting pixels includes a light emitting element, and each of the light sensing pixels includes a photoelectric conversion element. The readout circuit is connected to the light sensing pixels through readout lines. When operating in a photoplethysmography (PPG) sensing mode, the readout circuit may receive first sensing current from one or more of the light sensing pixels in a first sensing area adjacent to a sensing light emitting area that emits light, may receive second sensing current from one or more the light sensing pixels in a second sensing area spaced from the first sensing area, and may generate a PPG signal based on the first sensing current and the second sensing current.
1 . A display device comprising:
a display panel including light emitting pixels and light sensing pixels, each of the light emitting pixels including a light emitting element and each of the light sensing pixels including a photoelectric conversion element; and
a readout circuit connected to the light sensing pixels through readout lines,
wherein, in a photoplethysmography (PPG) sensing mode, the readout circuit is configured to receive first sensing current from one or more of the light sensing pixels in a first sensing area adjacent to a sensing light emitting area that is configured to emit light, receive second sensing current from one or more of the light sensing pixels in at least one second sensing area spaced from the first sensing area, and generate a PPG signal based on the first sensing current and the second sensing current,
wherein, in the PPG sensing mode, the first sensing area includes light emitting pixels that are configured to be turned off and light sensing pixels that are configured to be turned on,
wherein, in the PPG sensing mode, the at least one second sensing area includes light emitting pixels that are configured to be turned off and light sensing pixels that are configured to be turned on.
2 . The display device of claim 1 , wherein
the at least one second sensing area is spaced apart from the sensing light emitting area,
reflected light, which is emitted from the sensing light emitting area and reflected from a blood vessel of a finger of a user, is incident on the first sensing area, and
the reflected light is not incident on the at least one second sensing area.
3 . The display device of claim 2 , wherein the at least one second sensing area is positioned at one side of the sensing light emitting area.
4 . The display device of claim 2 , wherein
the display device includes a plurality of second sensing areas, and
the plurality of second sensing areas are positioned at different sides of the sensing light emitting area.
5 . The display device of claim 2 , wherein a size of the second sensing area is greater than a size of the first sensing area.
6 . The display device of claim 2 , wherein the sensing light emitting area surrounds at least a portion of the first sensing area in a plan view.
7 . The display device of claim 2 , wherein a distance between the sensing light emitting area and the second sensing area is greater than or equal to a width of the sensing light emitting area.
8 . The display device of claim 2 , wherein the readout circuit includes:
a sensing circuit configured to receive the first sensing current and the second sensing current through the readout lines, generating a first sensing signal corresponding to the first sensing current, and generating a first noise signal corresponding to the second sensing current;
a low pass filter configured to receive the first noise signal from the sensing circuit and generate a second noise signal; and
a noise eliminator configured to receive the first sensing signal from the sensing circuit, receive the second noise signal from the low pass filter, and generate a second sensing signal based on the first sensing signal and the second noise signal.
9 . The display device of claim 2 , wherein
the first sensing area includes a first-first sensing area and a first-second sensing area spaced apart from each other, and the reflected light is incident on each of the first-first sensing area and the first-second sensing area, and
the readout circuit is configured to receive first-first sensing current from one or more light sensing pixels in the first-first sensing area, receive first-second sensing current from one or more light sensing pixels in the first-second sensing area, and generate the PPG signal based on the first-first sensing current, the first-second sensing current, and the second sensing current.
10 . The display device of claim 9 , wherein the readout circuit includes:
a sensing circuit configured to receive the first-first sensing current, the first-second sensing current, and the second sensing current through the readout lines, generate a first sensing signal corresponding to the first-first sensing current, generate a second sensing signal corresponding to the first-second sensing current, and generate a first noise signal corresponding to the second sensing current;
a low pass filter configured to receive the first noise signal from the sensing circuit and generating a second noise signal;
a band rejection filter configured to receive the second sensing signal from the sensing circuit and generating a third noise signal; and
a noise eliminator configured to receive the first sensing signal from the sensing circuit, receive the second noise signal from the low pass filter, receive the third noise signal from the band rejection filter, and generate a third sensing signal based on the first sensing signal, the second noise signal, and the third noise signal.
11 . The display device of claim 10 , wherein the readout circuit further includes:
a band pass filter configured to receive the second sensing signal from the sensing circuit and generating a fourth sensing signal; and
an operational amplifier configured to receive the third sensing signal from the noise eliminator, receive the fourth sensing signal from the band pass filter, and generate a fifth sensing signal based on the third sensing signal and the fourth sensing signal.
12 . The display device of claim 1 , wherein
the second sensing area is adjacent to the sensing light emitting area, and
reflected light, which is emitted from the sensing light emitting area and reflected from a blood vessel of a finger of a user, is incident on each of the first sensing area and the second sensing area.
13 . The display device of claim 12 , wherein the readout circuit includes:
a sensing circuit configured to receive the first sensing current and the second sensing current through the readout lines, generate a first sensing signal corresponding to the first sensing current, and generate a first noise signal corresponding to the second sensing current;
a band rejection filter configured to receive the second sensing signal from the sensing circuit and generating a noise signal; and
a noise eliminator configured to receive the first sensing signal from the sensing circuit, receive the noise signal from the band rejection filter, and generate a third sensing signal based on the first sensing signal and the noise signal.
14 . The display device of claim 13 , wherein the readout circuit includes:
a band pass filter configured to receive the second sensing signal from the sensing circuit and generating a fourth sensing signal; and
an operational amplifier configured to receive the third sensing signal from the noise eliminator, receive the fourth sensing signal from the band pass filter, and generate a fifth sensing signal based on the third sensing signal and the fourth sensing signal.
15 . The display device of claim 1 , wherein in the PPG sensing mode,
the sensing light emitting area includes light emitting pixels that are turned on and light sensing pixels that are turned off.
16 . The display device of claim 15 , wherein
the light emitting pixels and the light sensing pixels are disposed in an entire display area of the display panel,
the display area includes the sensing light emitting area, the first sensing area, the second sensing area, and an off area, and
in the PPG sensing mode, the light emitting pixels and the light sensing pixels in the off area are turned off.
17 . The display device of claim 1 , wherein each of the light emitting pixels includes:
a first transistor configured to generate a driving current;
a second transistor configured to transfer a data signal in response to a write signal;
a third transistor configured to diode-connect the first transistor in response to a compensation signal;
a fourth transistor configured to transfer an initialization voltage to a gate of the first transistor in response to an initialization signal;
a fifth transistor configured to connect a line of a first power supply voltage and the first transistor in response to an emission signal;
a sixth transistor configured to connect the first transistor and the light emitting element in response to the emission signal;
a seventh transistor configured to transfer an anode initialization voltage to the light emitting element in response to a bypass signal;
an eighth transistor configured to transfer a bias voltage to a terminal of the first transistor in response to the bypass signal;
a storage capacitor connected between the line of the first power supply voltage and the gate of the first transistor; and
the light emitting element emitting light based on the driving current.
18 . The display device of claim 17 , wherein each of the light sensing pixels includes:
a ninth transistor configured to generate a sensing current based on a voltage of an anode of the photoelectric conversion element;
a tenth transistor configured to transfer a reset voltage to the anode of the photoelectric conversion element in response to a global reset signal;
an eleventh transistor configured to connect the ninth transistor and the readout line in response to the write signal; and
the photoelectric conversion element.
19 . The display device of claim 1 , further comprising:
a main processor configured to receive the PPG signal from the readout circuit and determine a biomarker of a user based on the PPG signal.
20 . A display device comprising:
a display panel including light emitting pixels and light sensing pixels, each of the light emitting pixels including a light emitting element and each of the light sensing pixels including a photoelectric conversion element; and
a readout circuit connected to the light sensing pixels through readout lines and configured to generate a photoplethysmography (PPG) signal based on sensing currents received from the light sensing pixels in a PPG sensing mode, and wherein in the PPG sensing mode,
one or more of the light emitting pixels in a sensing light emitting area are turned on, one or more of the light sensing pixels in the sensing light emitting area are turned off, and reflected light, which is emitted from the sensing light emitting area and reflected from a blood vessel of a finger of a user, is incident on a partial area of the display panel,
in a first sensing area where the reflected light is incident, one or more of the light emitting pixels are turned off and one or more of the light sensing pixels are turned on, and
in a second sensing area where the reflected light is not incident, one or more of the light emitting pixels are turned off and one or more of the light sensing pixels are turned on.
21 . A display device comprising:
a first pixel to emit light reflected by a finger of a user;
a light sensing pixel at a position to sense the reflected light;
a second pixel at a position that does not sense the reflected light;
a sensing circuit to generate a first sensing signal based on a sensing current output from the light sensing pixel and to generate a noise signal based on a sensing current output from the second pixel, and
a noise eliminator to subtract the noise signal from the first sensing signal to generate a biological signal of the user,
wherein the finger overlaps the first pixel and the second pixel and the light sensing pixel.
22 . The display device of claim 21 , wherein the biological signal is a photoplethysmography (PPG) signal.
23 . The display device of claim 21 , wherein the first pixel is configured to emit green light.
24 . The display device of claim 21 , wherein the sensing current output from the second pixel is generated based on one of a motion artifact, micro-motion, mis-positioning, ambient light, or breathing of the user.
25 . An electronic device comprising:
a display device; and
a power supply configured to provide power to the display device,
wherein the display device comprises:
a display panel including light emitting pixels and light sensing pixels, each of the light emitting pixels including a light emitting element and each of the light sensing pixels including a photoelectric conversion element; and
a readout circuit connected to the light sensing pixels through readout lines,
wherein, in a photoplethysmography (PPG) sensing mode, the readout circuit is configured to receive first sensing current from one or more of the light sensing pixels in a first sensing area adjacent to a sensing light emitting area that is configured to emit light, receive second sensing current from one or more of the light sensing pixels in at least one second sensing area spaced from the first sensing area, and generate a PPG signal based on the first sensing current and the second sensing current,
wherein, in the PPG sensing mode, the first sensing area includes light emitting pixels that are configured to be turned off and light sensing pixels that are configured to be turned on,
wherein, in the PPG sensing mode, the at least one second sensing area includes light emitting pixels that are configured to be turned off and light sensing pixels that are configured to be turned on.
26 . The electronic device of claim 25 , wherein in the PPG sensing mode, the sensing light emitting area includes light emitting pixels that are turned on and light sensing pixels that are turned off.