JPH0686174A - Infrared image sensor - Google Patents

Abstract

PURPOSE:To provide an infrared image sensor provided with a function eliminating a fixed pattern noise at the inside. CONSTITUTION:This image sensor is provided with a fixed pattern noise storage part 3 storing the fixed pattern noise generating in an image pickup part 1. A state that infrared ray is not made incident on an image sensor 10 is made, fixed pattern noise is stored in the storage part 3 and subsequently, the state that infrared ray is made incident on the image sensor 10 is made. The signal generated in the image pickup part 1 is imparted to an arithmetic part 9 via a storage part 2. In the arithmetic part 9, the difference of the output of the storage part 2 and the output of the storage part 3 corresponding to the same picture element is calculated and the result is outputted to the outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared image sensor having an image pickup section in which a plurality of infrared detecting elements are arranged.

[0002]

2. Description of the Related Art An infrared image sensor includes an image pickup section in which a plurality of infrared detecting elements (photodiodes) are arranged. When infrared rays enter the infrared detection element, an electric signal is generated by photoelectric conversion. This electric signal is sequentially transferred from the image pickup section by the reading means and output to the outside.

By the way, in an infrared image pickup device using this type of infrared image sensor, even if the shutter is closed and infrared rays do not enter the image pickup portion from the outside, due to the back radiation of the shutter and the dark current of the infrared detection element. A signal (fixed pattern noise) is generated. Therefore,
An infrared imaging device using a conventional infrared image sensor is provided with a processing device for removing fixed pattern noise from the output of the infrared image sensor.

[0004]

However, in the conventional infrared imaging device, it is necessary to provide a device for removing fixed pattern noise from the output of the infrared image sensor, which hinders downsizing and weight reduction of the device. There is a problem.

The present invention has been made in view of the above problems, and provides an infrared image sensor capable of removing fixed pattern noise inside the infrared image pickup device and achieving size reduction and weight reduction of the infrared image pickup device. The purpose is to do.

[0006]

An infrared image sensor according to the present invention includes an image pickup section for inputting infrared rays and converting it into an electric signal, and a fixed pattern noise storage section for storing fixed pattern noise generated in the image pickup section. It is characterized by having an arithmetic unit for performing an arithmetic operation on the output of the image pickup unit and the output of the fixed pattern noise storage unit.

[0007]

In the present invention, the fixed pattern noise storage unit for storing the fixed pattern noise generated in the image pickup unit is provided, and the calculation unit calculates the output of the image pickup unit and the output of the fixed pattern noise storage unit. To do. That is, the fixed pattern noise storage unit stores the output (that is, fixed pattern noise) of the imaging unit in a state where infrared rays are not incident. After the fixed pattern noise is stored in the fixed pattern noise storage unit, infrared rays are made incident on the imaging unit.
Then, the imaging unit outputs a signal in which fixed pattern noise is superimposed on the signal generated by the infrared rays. Therefore, a signal from which the fixed pattern noise is removed can be obtained by performing a calculation (difference calculation) between the output of the image pickup unit and the output of the fixed pattern noise storage unit in the calculation unit.

A storage unit for storing the output of the image pickup unit is provided, and the calculation unit sequentially calculates signals corresponding to the same pixel stored in the storage unit and the fixed pattern noise storage unit and outputs them to the outside. You may do it.

[0009]

Embodiments of the present invention will now be described with reference to the accompanying drawings.

FIG. 1 is a plan view showing an infrared image sensor according to an embodiment of the present invention, and FIG. 2 is a schematic view showing a positional relationship between the infrared image sensor and a shutter when the infrared image sensor is applied to an infrared image pickup device. It is a figure.

Infrared image sensor 10 according to the present embodiment
Is an image pickup unit 1 in which a plurality of photodiodes 7 are arranged, and a storage unit 2 in which a plurality of storage capacitors 6 are arranged.
And a fixed pattern noise storage section 3. A vertical CCD (charge coupled device) 5 for transferring an electric signal generated in the photodiode 7 by the photoelectric effect is provided to each of the image pickup unit 1, the storage unit 2, and the storage unit 3.
Is provided. Further, horizontal CCDs 4 are provided between the image pickup unit 1 and the storage unit 3 and on the end side of the storage unit 2, and the outputs of these horizontal CCDs 4 are inverted by a computing unit 9 via a buffer amplifier 8. It is adapted to be applied to the input terminal (-) and the non-inverting input terminal (+). The calculation unit 9 calculates the difference between the signals applied to the inverting input terminal and the non-inverting input terminal, and outputs the result to the outside.

As shown in FIG. 2, the infrared image sensor 10 includes a shutter 11 in the infrared image pickup device.
It is arranged behind.

Next, the operation of the infrared image sensor according to this embodiment will be described.

First, the shutter 11 is closed so that the infrared ray hν does not enter the infrared image sensor 10.
In this state, the fixed pattern noise generated in the image pickup unit 1 by the background radiation of the shutter 11 and the dark current of the photodiode 7 itself is transferred to the storage unit 3 by the vertical CCD 5, and the fixed pattern noise is stored in the storage capacitor 6 of the storage unit 3. Memorize After that, the operation of the vertical CCD 5 of the storage unit 3 is stopped.

Next, the shutter 11 is opened, and infrared rays hν
Enters the infrared image sensor 10. Then, the signal generated in the image pickup unit 1 is transferred to the storage unit 2 by the vertical CCD 5, and this signal is stored in the storage capacitor 6 of the storage unit 2. This signal is a signal in which fixed pattern noise is superimposed on the signal generated in the photodiode 7 by infrared rays.

Next, the vertical CCs of the storage unit 2 and the storage unit 3
The storage unit 2 and the storage unit 3 are formed by the D5 and the horizontal CCD 4.
The signals stored in 1 are sequentially supplied to the arithmetic unit 9 via the buffer amplifier 8. At this time, signals corresponding to the same pixel are simultaneously applied to the buffer amplifier 8. The calculation unit 9 outputs the difference between the two signals given to the inverting input terminal and the non-inverting input terminal as a time series signal.

By repeating the above operation for each frame, it is possible to obtain an image signal from which fixed pattern noise is removed.

In this embodiment, the image sensor itself removes the fixed pattern noise from the image signal, so that an external processing device for removing the fixed pattern noise is unnecessary, and the infrared image pickup device using the infrared image sensor is downsized. Also, it is possible to reduce the weight.

[0019]

As described above, according to the present invention, a fixed pattern noise storage unit for storing fixed pattern noise generated in the image pickup unit, an output of the image pickup unit and an output of the fixed pattern noise storage unit are provided. Since it has an arithmetic unit for performing arithmetic, it is not necessary to provide an external processing device for removing fixed pattern noise. Therefore, there is an effect that the infrared imaging device can be made smaller and lighter than conventional ones.

[Brief description of drawings]

FIG. 1 is a plan view showing an infrared image sensor according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a positional relationship between an infrared image sensor and a shutter when the infrared image sensor is applied to an infrared imaging device.

[Explanation of symbols]

 1; Imaging unit 2; Storage unit 3; Storage unit 4; Horizontal CCD 5; Vertical CCD 6; Storage capacitance 7; Photodiode 8; Buffer amplifier 9; Arithmetic unit

Claims (2)

[Claims] 1. An image pickup unit for inputting infrared rays and converting it into an electric signal, a fixed pattern noise storage unit for storing fixed pattern noise generated in the image pickup unit, an output of the image pickup unit and the fixed pattern noise storage unit. An infrared image sensor having an arithmetic unit for performing arithmetic operation with an output. 2. A storage unit for storing the output of the image pickup unit, wherein the calculation unit calculates the output of the storage unit and the output of the fixed pattern noise storage unit. 1. The infrared image sensor according to 1.