Radiant energy – Photocells; circuits and apparatus – Photocell controlled circuit
Reexamination Certificate
2002-05-17
2004-03-02
Porta, David (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Photocell controlled circuit
C250S2140RC, C348S307000, C327S514000
Reexamination Certificate
active
06700110
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical detector device that extracts moving objects in incident optical images.
2. Related Background Art
Optical detector devices fabricated by CMOS technologies can be built for a low cost on a single chip that includes the A/D converter circuits and the peripheral digital circuitry. Because of this, optical detector devices have been developed that, rather than just detecting light, include a variety of processing functions (for example, outline extraction or moving object extraction) on a single chip.
An optical detector device that has a moving object extraction function is described, for example, in Ishiwata, et al., “CMOS lmage Sensor for the Recognition of Three-Dimensional Gestures,” Image Information Media Association Technical Reports, Vol. 23, No. 30, pgs 13-16 (1999).
The optical detector device described in this reference is equipped with two capacitors and plurality of switches for each pixel, where the image data is stored in the first capacitors when one frame is captured and the image data is stored in the second capacitors when the next frame is captured, following which the differences between the image data stored in the respective first and second capacitors are derived.
By the above, the optical detector device extracts moving objects by performing image processing on the chip. This optical detector device provides separate image memory, whereas, conventionally, the image processing has had to be performed after storing the image data in an image memory provided separately.
SUMMARY OF THE INVENTION
In the optical detector device having a moving object extraction function, described in the aforementioned reference, it has been necessary to provide two capacitors and plurality of switches for each pixel, and also necessary to provide a differential circuit for finding the differences between the image data stored, respectively, in the first and second capacitors. Consequently, the area required on the chip for the circuitry for each pixel in this optical detector device has been large, and, as a result, this optical detector device has had the fatal flaw that it could not achieve a high aperture ratio, which determines the light response characteristics of the sensor, and thus could not provide images with high image quality.
The present invention was created to solve the aforementioned problem area, and is an optical detector device that extracts moving objects in the incident image with the object of reducing the surface area on the chip required for the circuitry for each pixel, thereby providing a high aperture ratio and superior optical response characteristics.
The optical detector device of the present invention comprises (A) an optical detector part that has an optical detector element that generate charges according to the intensity of incident light and a capacitor with a specific capacitance and that accumulates the charge generated by the aforementioned optical detector element, (B) an integrator circuit connected to the aforementioned capacitor, and having an integrated circuit capacitor with the aforementioned specific capacitance disposed between the input and output terminals of an amplifier, (C) a first switch equipped between the input terminal of said integrator circuit and the aforementioned optical detector part, and (D) a second switch equipped between the output terminal of the aforementioned integrator circuit and the aforementioned optical detector part. This will be explained in detail below.
A first optical detector device comprises (1) an optical detector part that is equipped with an optical detector element that generates a charge depending on the intensity of incident light and a capacitor that has a capacitance C
d
and that accumulates the charge generated by the optical detector element; (2) an integrator circuit which has an amplifier and an integrator circuit capacitor with a capacitance of C
f1
(where C
d
=C
f1
), disposed in parallel between the input terminal and the output terminal thereof, which accumulates the charge that is inputted into the input terminal in the integrator circuit capacitor, and outputs from its output terminal an integrated output according to the amount of the charge accumulated; (3) a first switch equipped between the optical detector part and the input terminal of the integrator circuit; and (4) a second switch equipped between the integrator circuit output terminal and the optical detector part.
In this first optical detector device, the charge that is generated according to the intensity of light that is incident upon an optical detector element in the optical detector device during a given time interval is stored in the capacitor. If the first switched is closed at the point in time this given time interval elapses, the charge that has been stored thus far in the capacitor moves to the integrator circuit capacitor in the integrator circuit.
The result is that the voltage at one terminal of the optical detector element changes by &Dgr;V to assume the reset level, and the integrator output, which is outputted from the integrator circuit, assumes a level according to the charge that was accumulated in the integrator circuit capacitor. When the second switch closes after the first switch has been opened, a voltage determined by the value of the integrator output, outputted from the integrator circuit, is placed into the capacitor in the optical detector element. Because the capacitance of the integrator circuit capacitor is the same as the capacitance of the capacitor in the optical detector element, the result is that the voltage at the terminal on one side of the optical detector element changes from the reset level by an amount equal to &Dgr;V.
For a specific time interval thereafter, the amount of charge that is generated, which depends on the intensity of light that is incident on the optical detector element, is stored in the capacitor. At the point in time this specific time interval elapses, the charge that has been accumulated in the capacitor is the superposition of the charge that is proportional to the voltage that was set according to the value of the integrator output when the second switch was closed, along with the charge that was generated in the optical detector element over the specific time interval. However, because the charges that are superposed have mutually differing signs, when the first switch is closed when this specific time interval elapses, the output of the integrator circuit is dependent on the increase or decrease of the intensity of light that is incident on the optical detector element.
A second optical detector device is equipped with (1) an optical detector part that has an optical detector element that generates charges according to the intensity of incident light, and a capacitor with a capacitance C
d
, and that accumulates the charges that are generated by the optical detector element; (2) an integrator circuit which has an amplifier and a integrator circuit capacitor equipped in parallel between the input terminal and the output terminal thereof, and which further comprises a capacitance switching means that is able to switch the capacitance of the integrator circuit capacitor between a capacitance C
d
and a smaller value, and which accumulates the charge that is inputted into the input terminal in the integrator circuit capacitor and outputs the integrator output, which is dependent on the amount of charge accumulated, from the output terminal; (3) a first switch that is equipped between the optical detector part and the input terminal of the integrator circuit; and (4) a second switch that is equipped between the output terminal of the integrator circuit and the optical detector part.
In this second optical detector device, the charges that are generated depending on the intensity of light that is incident on the optical detector elements of the optical detector part over a specific time interval are accumulated in the capacitors. When a first switch
Mizuno Seiichiro
Mukozaka Naohisa
Toyoda Haruyoshi
Hamamatsu Photonics K.K.
Lee Patrick J.
Morgan & Lewis & Bockius, LLP
Porta David
LandOfFree
Optical detector device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Optical detector device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical detector device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3279966