Solid-state imaging apparatus for motion detection

• US 6,624,849 B1
• Filed: 12/01/1998
• Issued: 09/23/2003
• Est. Priority Date: 12/08/1997
• Status: Expired due to Fees

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Nomura, Hitoshi
• Primary Examiner(s): Garber, Wendy R.
• Assistant Examiner(s): Villecco, John M
• Application Number:
  US09/203,799
• Time in Patent Office: 1,757 Days
• Field of Search: 348/14, 348/15, 348/169-172, 348/208.1, 348/155, 348/352, 348/302-304, 348/319-321, 348/699, 348/241, 348/308, 382/107, 382/236, 375/240.16, 257/258
• US Class Current: 348/241
• CPC Class Codes: H04N 25/48 Increasing resolution by shifting the sensor relative to the scene
• CPC Class Codes: H04N 25/707 Pixels for event detection
• CPC Class Codes: H04N 25/767 Horizontal readout lines, multiplexers or registers
• CPC Class Codes: H04N 3/155 Control of the image-sensor operation, e.g. image processing within the image-sensor

Abstract

A solid-state imaging apparatus for motion detection detects motion based on differences between pixel frames to make external image comparison processing unnecessary and to reduce erroneous detection of motion. The solid-state imaging apparatus includes a plurality of photoreceptive units arranged in a matrix of rows and columns, a plurality of vertical read lines disposed on each column of the plurality of photoreceptive units, a vertical transfer circuit that sequentially selects a specified row of the plurality of photoreceptive units and successively outputs to a vertical read line a previous pixel output, saved from a previous exposure of incident light on the photoreceptors, and a current pixel output newly generated from exposure of incident light on the photoreceptors, a comparison circuit that compares the previous pixel output and the current pixel output transferred by time division via the vertical read lines, a horizontal transfer circuit which serially transfers the comparison circuit'"'"'s signals, and a logical calculation circuit that performs a logical calculation on the comparison circuit'"'"'s signals and reduces the isolated regions of logical change to provide an object motion signal.

Claims

1. A solid-state imaging apparatus for motion detection, comprising:

a plurality of solid-state pixels each pixel having a photoreceptive element that generates a charge potential in response to incident light on the photoreceptive element and the pixel provides a pixel output of a pixel signal corresponding to the charge potential, the plurality of pixels arranged in a matrix having at least one row and one column;

a plurality of read lines in communication with a respective number of columns of the plurality of pixels;

a first transfer circuit that controls pixel output so that a first pixel signal is provided to a respective read line for each pixel of a selected row of pixels and a second pixel signal is provided to the respective read line for each pixel of the selected row of pixels in a time division manner;

a plurality of comparison circuits in communication a respective plurality of the vertical read lines, each comparison circuit compares the first pixel signal and the second pixel signal and provides a respective plurality of comparison signals;

a horizontal transfer circuit that receives the plurality of comparison signals and transfers the comparison signals serially;

a logical calculation circuit that serially receives the comparison signals and performs a logical calculation on the comparison signals and provides a logical calculation signal to detect motion of an object;

an image signal output circuit in communication with the plurality of read lines that provides an image signal corresponding to the incident light on the photoreceptive elements;

a level decision circuit that determines a level of the image signal from the image signal output circuit; and

an output switching circuit that switches and outputs the logical calculation signal and the comparison signal according to the level of the image signal.

2. The solid-state imaging apparatus for motion detection of claim 1, wherein the logical calculation circuit includes:

(a) a bit memory circuit that stores the comparison signal for each pixel; and

(b) a horizontal AND circuit that performs a logical AND calculation on the bit memory circuit contents and the comparison signal.

3. The solid-state imaging apparatus for motion detection of claim 1, wherein the logical calculation circuit includes:

(a) a line memory circuit that stores the comparison signal for each row; and

(b) a vertical AND circuit that performs a logical AND calculation on the line memory circuit contents and the comparison signal.

4. The solid-state imaging apparatus for motion detection of claim 1, wherein the logical calculation circuit includes:

(a) a frame memory circuit that stores the comparison signal for each matrix; and

(b) a time axis AND circuit that performs a logical AND calculation on the frame memory circuit contents and the comparison signal.

5. The solid-state imaging apparatus for motion detection of claim 1, wherein the first transfer circuit includes:

(a) a pixel output save unit, provided for each of the photoreceptive elements, that saves the charge potential from the photoreceptive element and provides pixel signals corresponding to the saved charge potential; and

(b) an output transfer gate, provided for each of the pixel output save units that connects and separates the pixel output save unit and the respective read line.

6. The solid-state imaging apparatus for motion detection of claim 5 wherein the pixel output save unit includes:

(a) an amplifier element that has a control region that saves the charge potential and that outputs the pixel signal corresponding to the charge potential saved in the control region;

(b) a transfer gate that transfers the charge potential created by the photoreceptive element to the amplifier element'"'"'s control region; and

(c) a reset circuit that resets the charge potential accumulated in the amplifier element'"'"'s control region.

7. The solid-state imaging apparatus for motion detection of claim 6, wherein the amplifier element is a junction type field-effect transistor, and pixel signals transferred via the transfer gate are directly accumulated in the gate region of the junction type field-effect transistor.

8. The solid-state imaging apparatus for motion detection of claim 1, wherein the comparison circuit compares the first pixel signal and the second pixel signal within a predetermined range, and outputs a binary signal according to the comparison.

9. An improved solid-state imaging apparatus for motion detection having a plurality of pixels, each pixel having a photoreceptive element that generates a charge potential when the photoreceptive element is subjected to incident light, a transfer gate in communication with the photoreceptive element, and an amplifier in communication with the transfer gate so that the transfer gate may be controlled by a first control signal to conduct the charge potential from the photoreceptive element to the amplifier and the transfer gate may be controlled by the first control signal to be non-conductive so that the charge potential of the photoreceptive element is not conducted to the amplifier, and a reset circuit in communication with the amplifier to reset a control region of the amplifier after the amplifier has received the charge potential, the solid-state imaging apparatus further including a vertical scanning circuit that controls output of pixel signals from the amplifier onto a respective plurality of read lines, the improvement comprising:

a plurality of comparison circuits in communication with a respective plurality of the read lines that compares sequential pixel signals and provides a plurality of comparison results;

a logical circuit that receives the plurality of comparison results and provides a moving object signal;

an image signal output circuit that receives the pixel signals and provides an image signal simultaneously with the moving object signal; and

an image signal level detector that compares the image signal to a threshold voltage and provides a level decision signal.

10. The solid-state imaging apparatus for motion detection of claim 9, further comprising a shift register that serially transfers the comparison results to the logical circuit.

11. The solid-state imaging apparatus for motion detection of claim 9 wherein the logical circuit comprises a D flip flop and an AND circuit.

12. The solid-state imaging apparatus for motion detection of claim 9 further comprising a frame memory circuit and wherein the logical circuit comprises an AND circuit.

13. The solid-state imaging apparatus for motion detection of claim 9 wherein each pixel further comprises a reset element to reset a potential on the amplifier between successive charge potentials received from the photoreceptive element.

14. The solid-state imaging apparatus for motion detection of claim 9 wherein the image signal output circuit comprises a plurality of processing circuits in communication with the read lines and that receives the pixel signals, and a horizontal scanning circuit that provides second control signals to control the processing circuits.

15. An improved solid-state imaging apparatus for motion detection having a plurality of pixels, each pixel having a photoreceptive element that generates a charge potential when the photoreceptive element is subjected to incident light, a transfer gate in communication with the photoreceptive element, and an amplifier in communication with the transfer gate so that the transfer gate may be controlled by a first control signal to conduct the charge potential from the photoreceptive element to the amplifier and the transfer gate may be controlled by the first control signal to be non-conductive so that the charge potential of the photoreceptive element is not conducted to the amplifier, and a reset circuit in communication with the amplifier to reset a control region of the amplifier after the amplifier has received the charge potential, the solid-state imaging apparatus further including a vertical scanning circuit that controls output of pixel signals from the amplifier onto a respective plurality of read lines, the improvement comprising:

a plurality of comparison circuits in communication with a respective plurality of the read lines that compares sequential pixel signals and provides a plurality of comparison results;

a logical circuit that receives the plurality of comparison results and provides a moving object signal;

an image signal output circuit that receives the pixel signals and provides an image signal simultaneously with the moving object signal; and

a first shift register and a second shift register and the logical circuit comprises a plurality of D flip flops and a plurality of logic elements.

16. A solid-state imaging apparatus for motion detection, comprising:

a plurality of pixels, a vertical scanning circuit that controls output of pixel signals from the plurality of pixels, a plurality of vertical read lines in communication with the plurality of pixels for conducting the pixel signals, a comparison circuit in communication with the vertical read lines that receives and compares successive pixel signals and provides a comparison signal, a logical calculation circuit in communication with the comparison circuit that receives the comparison signal and provides a moving object signal, and an image level detection circuit that determines a level of the image signal and provides an image level signal that is provided to the logical calculation circuit to reduce effects due to shot noise.

17. The solid-state imaging apparatus for motion detection of claim 16 further comprising having no analog to digital converter external to the solid-state imaging apparatus to provide a signal indicative of motion of an object.

18. The solid-state imaging apparatus for motion detection of claim 16 further comprising an image signal output circuit in communication with the vertical read lines for sequentially reading the pixel signals on the plurality of vertical read lines and providing an image signal that is output from the solid-state imaging apparatus simultaneously with the moving object signal from the logical calculation circuit.

19. A method of detecting motion of an object with a solid-state imaging apparatus having a plurality of pixels, each pixel including a photoreceptive element, an amplifier, and at least one transfer gate controlled by a first scanning circuit so that charge potential on the photoreceptive element can be transferred to the amplifier and the amplifier can provide a pixel signal corresponding to the charge potential to a respective one of a plurality of read lines, and a reset circuit to reset a control region of the amplifier after the amplifier receives the charge potential, comprising the steps:

exposing the photoreceptive element to first incident light having a detection object in a light path of the first incident light and thereby generating a first charge potential on the photoreceptive element;

transferring a first group of first charge potentials to the amplifiers and providing a first group of first analog pixel signals to the read lines;

exposing the photoreceptive element to second incident light and thereby generating a second charge potential on the photoreceptive element;

transferring a second group of second charge potentials to the amplifiers and providing a second group of second analog pixel signals to the read lines;

comparing at least one first analog pixel signal of the first group to a respective one second analog pixel signal of the second group and providing a comparison signal; and

performing a logical calculation on the comparison signal to provide a moving object signal;

conducting the pixel signals to an image output circuit and outputting an image signal from the image output circuit simultaneously with the moving object signal; and

determining a level of the image signal and providing an image signal level signal.

20. The method of claim 19 wherein the comparing step comprises comparing each of the analog pixel signals of the first group of pixel signals to a respective one of the analog pixel signals of the second group of pixels signals and providing a respective plurality of comparison signals.

21. The method of claim 20 further comprising the step of providing the plurality of comparison signals to a horizontal transfer circuit and serially outputting the comparison signals to perform the logical calculation on the comparison signals in sequence.

22. The method of claim 19 wherein the step of comparing pixel signals comprises comparing pixel signals of successive time divided signals to a threshold voltage to signals outside a predetermined range.

23. The method of claim 19 wherein the step of performing a logical calculation further comprises the step of using the image signal level signal to perform the logical calculation.