Compact image capture device

• US 6,141,048 A
• Filed: 08/19/1996
• Issued: 10/31/2000
• Est. Priority Date: 08/19/1996
• Status: Expired due to Fees

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Meyers, Mark Marshall
• Primary Examiner(s): Garber, Wendy
• Assistant Examiner(s): MOE, AUNG SOE
• Application Number:
  US08/699,306
• Time in Patent Office: 1,534 Days
• Field of Search: 348/294, 348/300, 348/301, 348/241, 348/243, 348/310, 348/308, 327/363, 327/261, 327/276, 327/538, 327/317, 250/208.1, 250/214 A
• US Class Current: 348/294
• CPC Class Codes: G02B 3/0043 Inhomogeneous or irregular arrays, e.g. varying shape, size, height
• CPC Class Codes: H04N 23/10 for generating image signals from different wavelengths
• CPC Class Codes: H04N 25/616 involving a correlated sampling function, e.g. correlated double sampling [CDS] or triple sampling
• CPC Class Codes: H04N 25/75 Circuitry for providing, modifying or processing image signals from the pixel array
• CPC Class Codes: H04N 25/772 comprising A/D, V/T, V/F, I/T or I/F converters

Abstract

The image capture device incorporates an array of photodetectors, utilizing an integral current mirror formed at each photodetector location to increase photodetector current output. A correlated double sampling circuit is also formed at each photodetector location to sum the current generated by the current mirror over each exposure period, so as to produce a voltage proportional to the radiation intensity incident at each photodetector location. The correlated double sampling circuit is used to reduce noise in the photodetected signal and to eliminate the effect of dark current. Combining the image capture device with a unique lenslet array forms an extremely compact optical array camera. An embodiment with a mechanical shutter is also disclosed.

Claims

1. A photosensor array of pixels each of the pixels comprising:

a current generating photodetector having a photodiode that is operatively coupled in combination with an associated multiplying current mirror located within the pixel and comprised of one input transistor and at least two output transistors where the generated photocurrent from each photodetector is multiplied by an integer equal to the number of output transistors in the associated multiplying current mirror and to provide the multiplied current as an output signal; and

wherein the output signal is selectively switched through a plurality of amplifiers having positive gain during periods where the photosensor is receiving incident light and negative gain during periods where the photosensor is not receiving incident light.

2. The photosensor array according to claim 1 and further comprising:

the plurality of amplifiers forming part of a correlated double sampling circuit connected to receive the output signal of an associated multiplying current mirror for providing an output that minimizes the dark current and noise from the current generating photodetectors.

3. The photosensor array according to claim 2 and further comprising:

row and column select means for connecting the output from the correlated double sampling circuits to a data bus.

4. The photosensor array according to claim 2 in combination with a camera wherein said photosensor array is exposed to the image to be captured by said camera so as to provide multiplied correlated double sampled current signals that represent said image to a data bus.

5. The photosensor array according to claim 1 and further comprising, a lenslet array having a number of lenslets corresponding in number to the number of current generating photodetectors each lenslet positioned so as to focus incident radiation onto an associated current generating photodetector, each lenslet being a refractive/diffractive lenslet wherein the center of the mechanical optical axis of each lenslet is displaced relative to the displacement of its associated photosensor'"'"'s radial distance from the optical axis of the lenslet located in the center of the array.

6. A photosensor array of pixels within each of the pixels comprising:

a current generating photodetector having a photodiode that is operatively coupled in combination with an associated multiplying current mirror located within the pixel and comprised of one input transistor and at least one output transistor having an emitter area which is equal to an integer multiple of the input transistor emitter area where the generated photocurrent from each photodetector is multiplied by an integer equal to the ratio of the output divided by the input transistor emitter area so as to provide an integer multiplied current as an output signal; and

wherein the output signal is selectively switched through a plurality of amplifiers having positive gain during periods where the photosensor is receiving incident light and negative gain during periods where the photosensor is not receiving incident light.

7. The photosensor array according to claim 6 and further comprising:

the plurality of amplifiers forming part of a correlated double sampling circuit connected to receive the output signal of an associated multiplying current mirror for providing an output that minimizes the dark current and noise from the current generating photodetectors.

8. The photosensor array according to claim 7 and further comprising:

row and column select means for connecting the output from the correlated double sampling circuits to a data bus.

9. The photosensor array according to claim 7 in combination with a camera wherein said photosensor array is exposed to the image to be captured by said camera so as to provide multiplied correlated double sampled current signals that represent said image to a data bus.

10. The photosensor array according to claim 6 and further comprising, a lenslet array having a number of lenslets corresponding in number to the number of current generating photodetectors each lenslet positioned so as to focus incident radiation onto an associated current generating photodetector, each lenslet being a refractive/diffractive lenslet wherein the center of the mechanical optical axis of each lenslet is displaced relative to the displacement of its associated photosensor'"'"'s radial distance from the optical axis of the lenslet located in the center of the array.

11. A photosensor array of pixels each of the pixels comprising:

a current generating photodetector having a photodiode that is operatively coupled in combination with an associated multiplying current mirror located within the pixel and comprised of one input transistor and at least one output transistor where the emitter base voltage on the input transistor is biased to produce an integer multiple of the input current at the output transistor'"'"'s emitter; and

wherein the output signal is selectively switched through a plurality of amplifiers having positive gain during periods where the photosensor is receiving incident light and negative gain during periods where the photosensor is not receiving incident light.

12. The photosensor array according to claim 11 and further comprising:

the plurality of amplifiers forming part of a correlated double sampling circuit connected to receive the output signal of an associated multiplying current mirror for providing an output that minimizes the dark current and noise from the current generating photodetectors.

13. The photosensor array according to claim 12 and further comprising:

row and column select means for connecting the output from the correlated double sampling circuits to a data bus.

14. The photosensor array according to claim 12 in combination with a camera wherein said photosensor array is exposed to the image to be captured by said camera so as to provide multiplied correlated double sampled current signals that represent said image to the data bus.

15. The photosensor array according to claim 11 and further comprising, a lenslet array having a number of lenslets corresponding in number to the number of current generating photodetectors each lenslet positioned so as to focus incident radiation onto an associated current generating photodetector, each lenslet being a refractive/diffractive lenslet wherein the center of the mechanical optical axis of each lenslet is displaced relative to the displacement of its associated photosensor'"'"'s radial distance from the optical axis of the lenslet located in the center of the array.