1. An image sensor, comprising:
a pixel array comprising a plurality of pixels arranged in columns and rows, one of the plurality of pixels detecting incident light and generating an analog signal in response to the detected incident light;
a reference voltage generation unit configured to generate a reference voltage that changes at a constant rate in a first operation mode and that alternately decreases and increases at the constant rate in a second operation mode;
an analog-digital conversion unit configured to convert the analog signal to a digital value a first number of times to generate a first number of digital values using the reference voltage and generate a digital signal by summing the first number of the digital values, the first number corresponding to a total number of decreases and increases of the reference voltage, the analog-digital conversion unit operating at a same speed in the first operation mode and the second operation mode to generate the digital signal; and
a control unit configured to control operations of the pixel array, the reference voltage generation unit, and the analog-digital conversion unit.
2. The image sensor of claim 1, wherein the first operation mode is a still image capturing mode and the second operation mode is a video recording mode.
3. The image sensor of claim 1, wherein the reference voltage generation unit receives a mode signal, a gain signal, and a count enable signal from the control unit, generates the reference voltage that decreases at the constant rate during an active period, in which the count enable signal is enabled, when the mode signal is at a first level corresponding to the first operation mode, and generates the reference voltage that alternately decreases and increases at the constant rate in a cycle of a sub period, which is a portion of the active period divided by a value of the gain signal, when the mode signal is at a second level corresponding to the second operation mode.
4. The image sensor of claim 1, wherein the reference voltage generation unit includes:
a resistor connected to a supply voltage; and
a current generation unit coupled between the resistor and a ground voltage, the current generation unit receiving a mode signal, a gain signal and a count enable signal from the control unit, the current generation unit generating a reference current that increases at the constant rate during an active period, in which the count enable signal is enabled, when the mode signal is at a first level corresponding to the first operation mode, the current generation unit generating the reference current that alternately increases and decreases at the constant rate in a cycle of a sub period, which is a portion of the active period divided by a value of the gain signal, when the mode signal is at a second level corresponding to the second operation mode,
wherein the reference current flows from the resistor to the ground voltage, and
wherein the reference voltage generation unit outputs the reference voltage from a node at which the resistor and the current generation unit are coupled.
5. The image sensor of claim 1, wherein the one of the plurality of the pixels generates a first analog signal corresponding to a reset component and a second analog signal corresponding to the detected incident light, and
wherein the analog-digital conversion unit generates the digital signal corresponding to an effective intensity of incident light among the detected incident light by performing a correlated double sampling (CDS) operation on the first analog signal and the second analog signal.
6. The image sensor of claim 5, wherein the analog-digital conversion unit includes:
a plurality of comparators, the plurality of comparators being respectively connected to a corresponding column of the pixel array, the plurality of comparators generating a comparison signal by comparing the first analog signal with the reference voltage and comparing the second analog signal with the reference voltage; and
a plurality of counters, the plurality of counters being respectively connected to a corresponding comparator of the plurality of comparators and receiving the comparison signal from the corresponding comparator, the plurality of counters receiving a count clock signal and an up-down control signal from the control unit, the plurality of counters generating the digital signal by performing one of a down-counting and an up-counting in response to the up-down control signal in synchronization with the count clock signal while the comparison signal is enabled.
7. The image sensor of claim 6, wherein the control unit provides the plurality of the counters with the count clock signal having a same frequency in the first operation mode and in the second operation mode.
8. The image sensor of claim 6, wherein one of the plurality of counters generates a first counting value by accumulatively performing the down-counting the first number of times from zero when the one of the plurality of counters receives the first analog signal from the pixel array, and generates a second counting value by accumulatively performing the up-counting the first number of times from the first counting value when the one of the plurality of counters receives the second analog signal from the pixel array, and
wherein the one of the plurality of counters outputs the second counting value as the digital signal.
9. The image sensor of claim 6, wherein the analog-digital conversion unit performs a binning operation on neighboring pixels of a same color in the second operation mode.
10. The image sensor of claim 9, wherein the analog-digital conversion unit performs a two-by-two binning operation on four neighboring pixels of the same color that are adjacent in a column direction and in a row direction of each other in the second operation mode.
11. The image sensor of claim 9, wherein the control unit consecutively selects rows, which are included in the pixel array, having pixels on which the binning operation is performed in the second operation mode.
12. The image sensor of claim 11, wherein the plurality of counters accumulatively performs the down-counting and the up-counting for the rows having pixels on which the binning operation is performed in the second operation mode.
13. The image sensor of claim 12, wherein the analog-digital conversion unit further includes a plurality of adders that generates a binning digital signal by summing the digital signals generated by counters which correspond to pixels on which binning operation is performed in the second operation mode.
14. The image sensor of claim 13, wherein the control unit includes a column driver that consecutively outputs the digital signals received from the plurality of the counters in the first operation mode and consecutively outputs the binning digital signals received from the plurality of the adders in the second operation mode.
15. The image sensor of claim 1, wherein the total number of increases and decreases of the reference voltage is a total number of changes of a rate of change of the reference voltage.
16. A camera system, comprising:
an image sensor configured to generate a digital signal corresponding to incident light;
a storage unit configured to store the digital signal; and
a processor configured to control operations of the image sensor and the storage unit,
wherein the image sensor comprises:
a pixel array comprising a plurality of pixels arranged in columns and rows, one of the plurality of pixels detecting incident light and generating an analog signal in response to the detected incident light;
a reference voltage generation unit configured to generate a reference voltage that changes at a constant rate in a first operation mode and that alternately decreases and increases at the constant rate in a second operation mode;
an analog-digital conversion unit configured to convert the analog signal to a digital value a first number of times to generate a first number of digital values using the reference voltage and generate the digital signal by summing the first number of the digital values, the first number corresponding to a total number of decreases and increases of the reference voltage, the analog-digital conversion unit operating at a same speed in the first operation mode and the second operation mode to generate the digital signal; and
a control unit configured to control operations of the pixel array, the reference voltage generation unit and the analog-digital conversion unit.
17. An image sensor comprising:
a pixel unit that detects light incident to the pixel unit and generates during a first active period of an operational mode of the image sensor a first analog signal that indicates a reset component of the pixel unit and generates during a second active period of the operational mode a second analog signal that indicates an intensity of the detected incident light;
a reference voltage generation unit that generates a reference voltage, the reference voltage decreasing at a constant rate during a first sub-period of the first active period and the second active period and the reference voltage increasing at the constant rate during a second sub-period of the first active period and the second active period; and
an analog-to-digital conversion unit that converts during the first sub-period and the second sub-period of the first active period the first analog signal to a first digital signal, converts during the first sub-period and the second sub-period of the second active period the second analog signal to a second digital signal, and outputs an effective intensity of the incident light based on a sum of a first difference between the first digital signal of the first sub-period of the first active period and the second digital signal of the first sub-period of the of the second active period and a second difference between the first digital signal of the second sub-period of the first active period and the second digital signal of the second sub-period of the second active period.
18. The image sensor of claim 17, wherein the operational mode is a first operational mode of the image sensor,
wherein the reference voltage generation unit generates the reference voltage as a first reference voltage in a first operational mode of the image sensor and generates a second reference voltage in a second operational mode of the image sensor, the second reference voltage only one of increasing and decreasing at the constant rate in the second operational mode.
19. The image sensor of claim 18, wherein the pixel unit, in the second operational mode, generates during a first active period a first analog signal that indicates a reset component of the pixel unit and generates during a second active period a second analog signal that indicates an intensity of the detected incident light,
wherein the reference voltage generation unit, in the second operational mode, generates the second reference voltage, and
wherein the analog-to-digital conversion unit, in the second operational mode, converts the analog signals generated by the pixel unit in the second operational mode into digital signals and outputs an effective intensity of the incident light detected by the pixel unit in the second operational mode based on a difference between digital signals converted from the analog signals generated by the pixel unit in the second operational mode.
20. The image sensor of claim 19, wherein the first operational mode is a video recording mode and the second operational mode is a still image capturing mode.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. A balanced microdevice comprising a substrate, at least one comb drive assembly having first and second comb drive members, the first comb drive member being mounted on the substrate and the second comb drive member overlying the substrate, at least one spring member having a first end portion coupled to the substrate and a second end portion coupled to the second comb drive member, the first comb drive member having a plurality of spaced-apart first comb drive fingers and the second comb drive member having a plurality of spaced-apart second comb drive fingers, the second comb drive member being movable between a first position in which the first and second comb drive fingers are not substantially fully interdigitated and a second position in which the first and second comb drive fingers are substantially fully interdigitated, a counterbalance carried by the substrate and coupled to the second comb drive member for inhibiting undesirable movement of the second comb drive member in response to externally applied accelerations to the microdevice.
2. The microdevice of claim 1 wherein the at least one comb drive assembly includes a plurality of the comb drive assemblies, the counterbalance being coupled to the second comb drive members of each of the comb drive assemblies.
3. The microdevice of claim 1 wherein the at least one comb drive assembly forms a rotary electrostatic microactuator that is fan-shaped in plan and has a base and a radial extremity, the second comb drive member being rotatable about an axis of rotation disposed adjacent the base.
4. The microdevice of claim 3 further comprising a movable member coupled to the second comb drive member and rotatable by the second comb drive member about the axis of rotation, the counterbalance including a weight coupled to the second comb drive member between the base and the radial extremity of the rotary electrostatic microactuator.
5. The microdevice of claim 1 wherein the second comb drive member is part of a movable structure rotatable about an axis of rotation, the movable structure extending radially outwardly from the axis of rotation and having the shape of a truncated sector of a circle when viewed in plan, the axis of rotation intersecting the plane of the substrate at a location spaced radially inwardly from the movable structure.
6. The microdevice of claim 5 wherein the counterbalance includes at least one additional comb drive assembly having such first and second comb drive members and a link for coupling the second comb drive member of the at least one additional comb drive assembly to the second comb drive member of the at least one first-named comb drive assembly for inhibiting undesirable movements of the second comb drive member of the at least one first-named comb drive assembly in response to externally applied accelerations to the microdevice.
7. The microdevice of claim 6 wherein the second comb drive member of the at least one additional comb drive assembly is part of an additional movable structure rotatable about an additional axis of rotation, the additional movable structure extending radially outwardly from the additional axis of rotation and having the shape of a truncated sector of a circle when viewed in plan, the additional axis of rotation intersecting the plane of the substrate at a location spaced radially inwardly from the additional movable structure.
8. The microdevice of claim 1 wherein the counterbalance includes at least one additional comb drive assembly having such first and second comb drive members and a link for coupling the second comb drive member of the at least one additional comb drive assembly to the second comb drive member of the at least one first-named comb drive assembly for inhibiting undesirable movements of the second comb drive member of the at least one first-named comb drive assembly in response to externally applied accelerations to the microdevice.
9. The microdevice of claim 1 wherein the at least one comb drive assembly forms a linear electrostatic microactuator.
10. The microdevice of claim 9 wherein the counterbalance includes an optical element and a lever assembly for coupling the optical element to the second comb drive member.
11. The microdevice of claim 10 wherein the lever assembly includes an anchor mounted on the substrate and a lever arm pivotably carried by the anchor, the lever arm having a first end portion coupled to the second comb drive member and a second end portion coupled to the optical element whereby movement of the first end portion by the second comb drive member in a first direction causes the optical element to move in a second direction substantially opposite to the first direction.
12. The microdevice of claim 11 wherein lever arm pivots about a pivot point and wherein the second comb drive member and the optical element are part of a movable framework having a center of mass substantially coincident with the pivot point.
13. A microdevice comprising a substrate, an element, an electrostatic microactuator carried by the substrate and a coupler for connecting the electrostatic microactuator to the element for moving the element in a direction of travel relative to the substrate, the electrostatic microactuator being mechanically balanced in the direction of travel relative to the element to inhibit undesirable movements of the element in the direction of travel in response to externally applied accelerations to the microdevice.
14. A microdevice as in claim 13 wherein the electrostatic microactuator is a linear electrostatic microactuator.
15. A microdevice as in claim 13 wherein the electrostatic microactuator is a rotary electrostatic microactuator.
16. A microdevice as in claim 15 wherein the rotary electrostatic microactuator rotates about an axis of rotation and has a movable portion and wherein the element and the movable portion of the rotary electrostatic microactuator have a center of mass that is substantially coincident with the axis of rotation.
17. A microdevice as in claim 13 wherein the element is a lens.
18. A microdevice as in claim 13 wherein the element is a mirror.
19. A microdevice comprising a substrate, an element, an electrostatic microactuator carried by the substrate and a coupler for connecting the electrostatic microactuator to the element for moving the element in a direction of travel relative to the substrate, counterbalancing means carried by the substrate and coupled to the electrostatic microactuator for mechanically balancing the electrostatic microactuator in the direction of travel relative to the element to inhibit undesirable movements of the element in the direction of travel in response to externally applied accelerations to the microdevice.
20. A microdevice as in claim 19 wherein the electrostatic microactuator is a rotary electrostatic microactuator.
21. A microdevice as in claim 20 wherein the rotary electrostatic microactuator extends in a plane and rotates about an axis of rotation extending perpendicularly of the plane and outside the confines of the microactuator.
22. A microdevice as in claim 21 wherein the rotary electrostatic microactuator rotates about the axis of rotation, the counterbalancing means including an additional rotary electrostatic microactuator extending in the plane and rotating about an additional axis of rotation and a link for coupling the additional rotary electrostatic microactuator to the first-named rotary electrostatic microactuator so that the additional rotary electrostatic microactuator mechanically balances the first-named rotary electrostatic microactuator in the direction of travel.
23. A microdevice as in claim 22 wherein the first-named rotary electrostatic microactuator rotates about the axis of rotation in a first direction when the additional rotary electrostatic microactuator rotates about the additional axis of rotation in a second direction that is opposite to the first direction.
24. A microdevice comprising a substrate, an element, first and second electrostatic microactuators carried by the substrate and a link carried by the substrate and connected to the first and second electrostatic microactuators for counterbalancing the first and second electrostatic microactuators relative to each other.
25. A microdevice as in claim 24 wherein at least one of the first and second electrostatic microactuators is a rotary electrostatic microactuator.
26. A microdevice as in claim 24 wherein each of the first and second electrostatic microactuators is rotary electrostatic microactuator.
27. A rotary electrostatic microactuator comprising a substrate extending substantially in a plane, at least one comb drive assembly carried by the substrate and having a first comb drive member mounted on the substrate and a second comb drive member, the first comb drive member being provided with a plurality of first comb drive fingers and the second comb drive member being provided with a plurality of second comb drive fingers, first and second spaced-apart springs, each of the first and second springs having a first end portion coupled to the substrate and a second end portion coupled to the second comb drive member for suspending the second comb drive member over the substrate, the second comb drive member being part of a movable structure that is rotatable about an axis of rotation between a first position in which the first and second comb drive fingers are not substantially fully interdigitated and a second position in which the first and second comb drive fingers are substantially fully interdigitated, the movable structure extending radially outwardly from the axis of rotation and having a shape of a truncated sector of a circle when viewed in plan, the axis of rotation intersecting the plane of the substrate at a location spaced radially inwardly from the movable structure.
28. A microactuator as in claim 27 wherein the at least one comb drive assembly is disposed between the first and second springs.
29. The microactuator of claim 27 wherein the first and second comb drive fingers are each arcuate in shape.
30. The microactuator of claim 29 wherein the first comb drive member has a midpoint in the space between each adjacent pair of the first comb drive fingers, the second comb drive member being movable between a first position in which each second comb drive finger is not substantially fully interdigitated with an adjacent pair of first comb drive fingers and a second position in which each such second comb drive finger is substantially fully interdigitated with such adjacent pair of first comb drive fingers, each of the second comb drive fingers being offset relative to the midpoint between the adjacent pair of first comb drive fingers when in the first position and being substantially centered on such midpoint when in the second position.
31. A microactuator as in claim 27 wherein each of the second comb drive fingers is joined to the second elongate member at a second oblique angle.
32. A microactuator as in claim 31 wherein each of the first comb drive fingers is joined to the first elongate member at a first oblique angle.
33. A microactuator as in claim 32 wherein the first and second oblique angles are equal.
34. A rotary electrostatic microactuator comprising a substrate extending substantially in a plane, a plurality of comb drive assemblies carried by the substrate, each of the comb drive assemblies having a first comb drive member mounted on the substrate and a second comb drive member, each of the first and second comb drive members being provided with arcuate comb drive fingers, first and second spaced-apart springs, each of the first and second springs having a first end portion coupled to the substrate and a second end portion coupled to at least one of the second comb drive members for suspending the second comb drive members over the substrate, the second comb drive members being part of a movable structure that is rotatable about an axis of rotation between a first position in which the comb drive fingers of the first and second comb drive members are not substantially fully interdigitated and a second position in which the comb drive fingers of the first and second comb drive members are substantially fully interdigitated, the movable structure extending radially outwardly from the axis of rotation and having a shape of a truncated sector of a circle when viewed in plan, the axis of rotation intersecting the plane of the substrate at a location spaced radially inwardly from the movable structure.
35. The rotary microactuator of claim 34 wherein the movable structure subtends an angle of 90 or less about the axis of rotation.
36. The rotary microactuator of claim 34 wherein each of the first and second springs have inner and outer radial portions, the inner radial portions being coupled to the substrate.
37. The rotary microactuator of claim 34 wherein the arcuate comb drive fingers have a radius commencing substantially at the axis of rotation.
38. The rotary microactuator of claim 34 wherein each of the first and second comb drive members has an elongate truss, each of the arcuate comb drive fingers having a first portion coupled to the truss and a second portion extending from the first portion, the first portion having a first width and the second portion having a second width less than the first width whereby the second portions of the arcuate comb drive fingers of the second comb drive member sequentially interdigitate along the truss between adjacent first portions of the arcuate comb drive fingers of the first comb drive member during movement of the movable structure to the second position.
39. The rotary microactuator of claim 34 wherein the arcuate comb drive fingers of the second comb drive member vary in length so as to sequentially interdigitate along the second comb drive member during movement of the movable structure to the second position.