Controlling electronic shutter in image sensors
View Patent ↗An image sensor includes an electronic shutter layer that drains charge away from the photosensitive regions during an electronic shutter operation. A signal is applied to the electronic shutter layer through a contact. Prior to performing an electronic shutter operation, a determination is made as to whether or not a current level in the electronic shutter layer substantially equals or exceeds a threshold current level. If the current level in the electronic shutter layer substantially equals or exceeds the threshold current level, the electronic shutter operation is not performed. The electronic shutter operation is performed if the current level in the electronic shutter layer does not substantially equal or exceed the threshold current level.
1. A method for operating an image sensor that includes an electronic shutter layer and a contact to the electronic shutter layer, the method comprising:
prior to performing an electronic shutter operation, determining whether a current level in the electronic shutter layer exceeds a threshold current level; and
when the current level in the electronic shutter layer exceeds the threshold current level, not performing the electronic shutter operation.
2. The method as in claim 1 , further comprising performing the electronic shutter operation when the current level in the electronic shutter layer does not exceed the threshold current level.
3. The method as in claim 1 , further comprising performing the electronic shutter operation when the current level in the electronic shutter layer equals the threshold current level.
4. The method as in claim 2 , further comprising:
setting a state of an alert signal to a first state when the current level in the electronic shutter layer does not exceed the threshold current level;
setting a state of an alert signal to a second state when the current level in the electronic shutter layer exceeds the threshold current level;
transmitting a drive pulse signal to an electronic shutter pulse driver component when the state of the alert signal is at the first state to cause the electronic shutter operation to be performed; and
not transmitting the drive pulse signal to the electronic shutter pulse driver component when the state of the alert signal is at the second state to cause the electronic shutter operation to not be performed.
5. The method as in claim 4 , wherein transmitting a drive pulse signal to an electronic shutter pulse driver component when the state of the alert signal is at the first state causes a signal level of a shutter signal to be changed from a first level to a second level for the electronic shutter operation.
6. The method as in claim 4 , wherein not transmitting the drive pulse signal to the electronic shutter pulse driver component when the state of the alert signal is at the second state causes a signal level of a shutter signal to not be changed from a first level to a second level to not perform the electronic shutter operation.
7. The method as in claim 2 , wherein performing the electronic shutter operation comprises changing a signal level of a shutter signal from a first level to a second level.
8. The method as in claim 7 , wherein not performing the electronic shutter operation comprises not changing the signal level of the shutter signal to the second level.
9. The method as in claim 8 , further comprising changing the signal level of the shutter signal to a third level.
10. The method as in claim 8 , further comprising scaling the signal level of the shutter signal to a third level.