Pixel circuit selecting to output time difference data or image data
There is provided a pixel circuit capable of outputting time difference data or image data, and including a first temporal circuit and a second temporal circuit. The first temporal circuit is used to store detected light energy of a first interval and a second interval as the time difference data. The second temporal circuit is used to store detected light energy of the second interval as the image data. The pixel circuit is used to output a pulse width signal corresponding to the time difference data or the image data in different operating modes.
1. A pixel circuit, comprising:
a photodiode, configured to generate light energy;
a first temporal circuit, comprising:
a first capacitor having a first end coupled to the photodiode;
a second temporal circuit, comprising:
a second capacitor having a first end coupled to the photodiode, wherein
a second end of the first capacitor is coupled to an inverting input terminal of a first comparator, which is arranged outside the pixel circuit and shared by the first temporal circuit and other pixel circuits, and
a second end of the second capacitor is coupled to an inverting input terminal of a second comparator, which is arranged outside the pixel circuit and shared by the second temporal circuit and the other pixel circuits; and
a transfer transistor, connected between the photodiode and the first end of the first capacitor as well as the first end of the second capacitor, and configured to transfer the light energy to the first temporal circuit in a first interval and a second interval, and transfer the light energy to the second temporal circuit in the second interval,
wherein the first temporal circuit is configured to record a light energy variation from the photodiode between the first interval and the second interval, and
the second temporal circuit is configured to record detected light energy from the photodiode in the second interval.
2. The pixel circuit as claimed in claim 1 , wherein the other pixel circuits are multiple pixel circuits at a same column of a pixel array as the pixel circuit.
3. The pixel circuit as claimed in claim 1 , further comprising:
a reset transistor, connected between the transfer transistor and the first end of the first capacitor as well as the first end of the second capacitor.
4. The pixel circuit as claimed in claim 1 , wherein
the first temporal circuit further comprises a second transistor connected between the first capacitor and the first comparator,
the second temporal circuit further comprises a second transistor connected between the second capacitor and the second comparator, and
the second transistor of the first temporal circuit is not conducted in the second interval, the second transistor of the second temporal circuit is not conducted in the first interval.
5. The pixel circuit as claimed in claim 4 , further comprising:
a first source follower, connected to the first capacitor and the second transistor of the first temporal circuit;
a first row selection transistor, connected between the first source follower and the first comparator;
a second source follower, connected to the second capacitor and the second transistor of the second temporal circuit; and
a second row selection transistor, connected between the second source follower and the second comparator.
6. The pixel circuit as claimed in claim 1 , wherein a non-inverting input terminal of the first comparator is configured to
receive a ramp signal to cause the first comparator to output a pulse width signal corresponding to the light energy variation, or
sequentially receive an upper threshold voltage and a lower threshold voltage to confirm whether the light energy variation exceeds the upper threshold voltage or the lower threshold voltage.
7. The pixel circuit as claimed in claim 1 , wherein a non-inverting input terminal of the second comparator is configured to
receive a ramp signal to cause the second comparator to output a pulse width signal corresponding to the detected light energy.
8. A pixel circuit, comprising:
a source follower;
a first temporal circuit, comprising:
a first capacitor having a first end coupled to the source follower;
a second temporal circuit, comprising:
a second capacitor having a first end coupled to the source follower, wherein
a second end of the first capacitor is coupled to an inverting input terminal of a first comparator, which is arranged outside the pixel circuit and shared by the first temporal circuit and other pixel circuits, and
a second end of the second capacitor is coupled to an inverting input terminal of a second comparator, which is arranged outside the pixel circuit and shared by the second temporal circuit and the other pixel circuits;
a first source follower, connected to the second end of the first capacitor;
a first row selection transistor, connected between the first source follower and the first comparator;
a second source follower, connected to the second end of the second capacitor; and
a second row selection transistor, connected between the second source follower and the second comparator.
9. The pixel circuit as claimed in claim 8 , further comprising:
a photodiode, configured to generate light energy;
a transfer transistor, connected between the photodiode and the source follower, and configured to transfer the light energy to the first temporal circuit via the source follower in a first interval and a second interval, and transfer the light energy to the second temporal circuit via the source follower in the second interval; and
a reset transistor, connected between the transfer transistor and the source follower.
10. The pixel circuit as claimed in claim 9 , wherein
the first temporal circuit is configured to record a light energy variation from the photodiode between the first interval and the second interval, and
the second temporal circuit is configured to record detected light energy from the photodiode in the second interval.