EVENT-BASED SENSOR, USER DEVICE INCLUDING THE SAME, AND OPERATION METHOD OF THE SAME
An event-based sensor includes a dummy pixel that generates a dark current, a current mirror that generates a mirrored current using the dark current, and a sensing pixel that generates a sense current based on an intensity of incident light, and outputs an activation signal, indicating whether a variation in the incident light is sensed, based on a light current that is obtained by subtracting the mirrored current from the sense current.
1 . An event-based sensor comprising:
a dummy pixel configured to generate a dark current;
a current mirror configured to generate a mirrored current using the dark current; and
a sensing pixel configured to generate a sense current based on an intensity of incident light, and output an activation signal based on a light current obtained by subtracting the mirrored current from the sense current,
wherein the activation signal indicates whether a variation in the incident light is sensed.
2 . The event-based sensor of claim 1 , wherein a magnitude of the dark current is the same as a magnitude of the mirrored current
3 . The event-based sensor of claim 1 , wherein the current mirror mirrors the dark current flowing to the dummy pixel to generate and output the mirrored current to the sensing pixel.
4 . The event-based sensor of claim 1 , wherein the dummy pixel comprises a photo diode configured to generate the dark current.
5 . The event-based sensor of claim 4 , wherein the dummy pixel further comprises a current-voltage converter configured to convert the dark current into a voltage.
6 . The event-based sensor of claim 4 , wherein the sensing pixel comprises:
a photo diode configured to generate the sense current based on the intensity of the incident light; and
a pixel circuit configured to output the activation signal based on the light current, and
wherein the current mirror provides the mirrored current to the sensing pixel.
7 . The event-based sensor of claim 6 , wherein the pixel circuit of the sensing pixel comprises:
a current-voltage converter configured to convert the light current into a voltage;
an amplifier configured to amplify a variation in the converted voltage; and
an event determination circuit configured to compare the amplified variation with a threshold value, and output the activation signal based on a result of the comparison.
8 . The event-based sensor of claim 7 , wherein the dummy pixel further comprises a current-voltage converter configured to convert the dark current into a voltage.
9 . The event-based sensor of claim 1 , further comprising another sensing pixel,
wherein the current mirror outputs another mirrored current using the dark current, and
wherein the other sensing pixel is configured to generate another sense current based on an intensity of incident light, and output another activation signal based on another light current obtained by subtracting the other mirrored current from the other sense current.
10 . The event-based sensor of claim 1 , further comprising another dummy pixel configured to generate another dark current,
wherein the current mirror is configured to output the mirrored current based on a sum of the dark current and the other dark current, and
wherein the dark current and the other dark current are generated in a light-free environment.
11 . The event-based sensor of claim 1 , further comprising another dummy pixel configured to generate another dark current,
wherein the current mirror is configured to output the mirrored current based on an average of the dark current and the other current, and
wherein the dark current and the other dark current are generated in a light-free environment.
12 . An event-based sensor comprising:
a dummy pixel configured to generate a dark current and convert the dark current into a voltage;
a transistor configured to replicate the dark current based on the voltage and output a mirrored current as a result of the replication; and
a sensing pixel configured to generate a sense current based on an intensity of incident light, and output an activation signal based on the mirrored current and the sense current.
13 . The event-based sensor of claim 12 , wherein the dummy pixel comprises:
a photo diode configured to generate the dark current; and
a current-voltage converter configured to convert the dark current into the voltage, and
wherein the sensing pixel comprises:
a photo diode configured to generate the sense current; and
a pixel circuit configured to output the activation signal based on a light current obtained by subtracting the mirrored current from the sense current.
14 . The event-based sensor of claim 13 , wherein the transistor comprises a source configured to receive a power supply voltage, a drain connected with a cathode of the photo diode of the sensing pixel, and a gate connected to receive the voltage.
15 . The event-based sensor of claim 14 , wherein the sensing pixel further comprises a current-voltage converter configured to generate a voltage based on the mirrored current and the sense current, and
wherein the current-voltage converter of the dummy pixel receives a first reference voltage, and the current-voltage converter of the sensing pixel receives a second reference voltage, and
wherein at least one of the first and second reference voltages is adjusted such that a magnitude of the dark current is the same as a magnitude of the mirrored current.
16 . The event-based sensor of claim 12 , wherein the dummy pixel comprises:
a photo diode configured to generate the dark current; and
a pixel circuit comprising an event determination circuit configured to output an activation signal based on the dark current,
wherein the sensing pixel comprises:
a photo diode configured to generate the sense current; and
a pixel circuit comprising an event determination circuit configured to output the activation signal based on a light current obtained by subtracting the mirrored current from the sense current, and
wherein the event determination circuit of the dummy pixel circuit is deactivated.
17 . The event-based sensor of claim 16 , wherein the pixel circuit of the dummy pixel comprises:
a current-voltage converter configured to convert the dark current into the voltage; and
a time-variant circuit configured to output a variation in the voltage,
wherein the event determination circuit of the pixel circuit of the dummy pixel is configured to output the activation signal based on the variation in the dark current, and
wherein the time-variant circuit and the event determination circuit of the pixel circuit of the dummy pixel are deactivated.
18 . A sensor comprising:
at least one sensing pixel configured to detect light incident thereon, and generate at least one sense current, respectively, based on the detected light; at least one dummy pixel configured to generate at least one dark current, respectively, under a light-free condition; and
a current mirror configured to receive the at least one dark current, and output at least one mirrored current to the at least one sensing pixel, respectively,
wherein the at least one sensing pixel generates at least one light current, respectively, by subtracting the at least one mirrored current from the at least one sense current, respectively, and generates at least one activation signal based on the at least one light current, respectively, and
wherein the sensor further comprises a controller configured to generate an event signal based on the at least one activation signal.
19 . The sensor of claim 18 , wherein a number of the at least one sensing pixel and a number of the at least one dummy pixel is different.
20 . The sensor of claim 19 , wherein each of the at least one mirrored current is an average current of the at least one dark current.
21 - 25 . (canceled)