Light sensing device

• US 5,748,303 A
• Filed: 12/31/1996
• Issued: 05/05/1998
• Est. Priority Date: 12/31/1996
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Clark, Lawrence T., Spaw, William J., Davis, Derek L., Korta, Jean-Charles
• Primary Examiner(s): Pham, Hoa Q.
• Application Number:
  US08/775,833
• Time in Patent Office: 490 Days
• Field of Search: 356/213, 356/218, 356/221, 356/229, 356/230, 250/214 R, 250/214.1, 250/214 C, 324/76.24, 324/76.38, 324/76.15
• US Class Current: 356/229
• CPC Class Codes: G01J 1/46 using a capacitor
• CPC Class Codes: H04N 25/533 by using differing integration times for different sensor regions
• CPC Class Codes: H04N 25/57 Control of the dynamic range
• CPC Class Codes: H04N 25/77 Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components

Abstract

A light sensing device including at least one light sensor is provided. The at least one light sensor is configured to be exposed to a light image. In response to the light image, the at least one light sensor is configured to generate a first signal. The light sensing device further includes a measuring device coupled to the at least one light sensor. The light sensing device also includes a sampling generator configured to generate a sampling signal to the measuring device. The sampling signal is inhibited when the first signal is lesser than or equal to a predetermined value. Upon inhibition of the sampling signal, the measuring device retains a measure of the first signal.

Claims

1. A light sensing device comprising:

at least one light sensor configured to be exposed to a light image and responsive thereto to generate a first signal;

a measuring device coupled to said at least one light sensor;

a sampling generator configured to generate a sampling signal to said measuring device, said sampling signal being inhibited when said first signal is lesser than or equal to a predetermined value; and

wherein upon inhibition of said sampling signal, said measuring device retaining a measure of said first signal.

2. The light sensing device of claim 1 further including a comparator circuit coupled to said at least one light sensor and to said measuring device, said comparator configured to inhibit said sampling signal when said first signal is lesser than or equal to a predetermined value.

3. The light sensing device of claim 2 wherein said comparator circuit is coupled to a reference signal that prevents said comparator circuit from inhibiting said sampling signal when said sampling signal is active.

4. The light sensing device of claim 2 wherein said comparator circuit is coupled to a predetermined number of adjacent pixels.

5. The light sensing device of claim 1 wherein said light image has an intensity represented by a floating point number that includes a mantissa part and an exponent part and said measuring device includes first and second measuring devices configured to retain a measure of said mantissa part and said exponent part respectively.

6. The light sensing device of claim 5 wherein said sampling signal pulses at discrete exponentially increasing intervals of time.

7. The light sensing device of claim 6 wherein said reference signal includes a ramp signal.

8. A method for sensing a light signal received by at least one light sensor of an array of light sensors, the method comprising the steps of:

converting said light signal into a first electrical signal having a measure including a mantissa part and an exponent part; and

for each light sensor of said array, measuring said mantissa part and said exponent part.

9. The method of claim 8 further including, before said measuring step, providing first and second measuring devices configured to retain a measure of said mantissa and said exponent respectively.

10. The method of claim 8 wherein said measuring step includes sampling said first and second measuring devices according to a sampling signal.

11. The method of claim 10 wherein said sampling signal pulses at discrete exponentially increasing intervals of times.

12. A light sensing device comprising:

at least one light sensor configured to be exposed to a light image that has an intensity represented by a floating point number including a mantissa part and an exponent part;

a first measuring device coupled to said at least one light sensor;

a second measuring device;

a sampling generator configured to generate a sampling signal to said first and second measuring devices, said sampling signal inhibited when said measure of said mantissa is lesser than or equal to a predetermined value; and

wherein upon inhibition of said sampling signal, said first and second measuring devices configured to retain a measure of said mantissa and exponent respectively.

13. The light sensing device of claim 12 further including a comparator circuit coupled to said at least one light sensor and to said first measuring device, said comparator configured to inhibit said sampling signal when said mantissa is lesser than or equal to a predetermined value.

14. The light sensing device of claim 13 wherein said comparator circuit is coupled to a reference signal that prevents said comparator circuit from inhibiting said sampling signal when said sampling signal is active.

15. The light sensing device of claim 14 wherein said sampling signal pulses at discrete exponentially increasing intervals of time.

16. The light sensing device of claim 15 wherein said reference signal includes a ramp signal.

17. The light sensing device of claim 13 wherein said comparator circuit is coupled to a predetermined number of adjacent pixels.