JPH0787399A - Pyrolectric infrared image pickup device - Google Patents

Abstract

PURPOSE:To obtain a pyroelectric infrared image pickup device in which a clear picture can be obtained by reducing a scanning switching noise generated at the time of the scanning and the reading of a two-dimensional pyroelectric infrared ray detecting element. CONSTITUTION:A dummy picture element arrayed in the form of a line is installed in the two-dimensional pyroelectric infrared ray detecting element 31, and the scanning switching noise outputted from the dummy picture element is stored in a canceling data memory 33 installed at the outside, and a noise cancellation circuit 34 subtracts it from the output of effective picture elements 9 to 17, and cancels the noise. Besides, it is permissible that the dummy picture element arrayed in the form of a line is installed, and the scanning switching noise is subtracted from the output of the effective picture element in the two-dimensional infrared ray detecting element. Further, it is permissible that the dummy picture element arrayed two-dimensionally is installed, and the scanning switching noise is subtracted from the output of the effective picture element in the two-dimensional pyroelectric infrared ray detecting element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to reduction of scanning switching noise generated during scanning and reading of element output in a pyroelectric infrared imaging device using a two-dimensional pyroelectric infrared detecting element.

[0002]

2. Description of the Related Art FIG. 8 is a block diagram showing an embodiment of a conventional pyroelectric infrared imaging device. In the figure, 1 is an infrared optical system, 2 is a two-dimensional pyroelectric infrared detecting element installed on the image plane of the infrared optical system 1, and 3 is an infrared optical system 1 and a two-dimensional pyroelectric infrared detecting element. 2 is a chopper arranged between the chopper 4 and 4, a chopper rotation angle detecting means attached to the chopper 3, 5 is a timing generation circuit, 6 is an external amplifier, 7 is an A / D converter, and 8 is a frame memory. Next, FIG. 9 is a configuration diagram of the two-dimensional pyroelectric infrared detection element 2. In the figure, 9 to 17 are effective pixels, 18 is an X-direction scanner, 19 is a Y-direction scanner, and 20 is a built-in amplifier connected to the X-direction scanner 18. Effective pixel 9
Is composed of a pyroelectric sensor 21 and a read switch 22, and the other effective pixels 10 to 17 also have the same structure as the effective pixel 9. The effective pixels 9 to 17 are two-dimensionally arranged to form a two-dimensional pyroelectric infrared detection element 2. Here, for the sake of simplification of description, a pixel having 3 × 3 pixels is shown. Next, the signals shown in FIGS. 8 and 9 will be described. 23 is an X-direction scanner drive signal, 24 is a Y-direction scanner drive signal, 25 is an element output signal, 26 is a chopper rotation angle signal, 27 is an A / D conversion timing signal, 28 is an external amplifier output signal, and 29 is A /
D converter output data, and 30 is image data.

Next, the operation will be described. First, the chopper 3 is rotated. Chopper 3 when chopper 3 is "closed"
When the chopper 3 is "open", the radiant energy of the object to be imaged collected by the infrared optical system 1 is the pyroelectric sensor 21.
Incident on. As a result, a temperature change corresponding to the radiant energy of the object to be imaged occurs in each pyroelectric sensor 21 in synchronization with the opening and closing of the chopper 3, and a voltage having an amplitude proportional to this temperature change is generated as shown in FIG. Each is output in synchronization with the opening and closing of the chopper 3. Chopper rotation angle detection means 4
Detects the open / closed state of the chopper 3, and outputs the chopper rotation signal 2
6 is output to the timing generation circuit 5. The timing generation circuit 5 outputs an X-direction scanner drive signal 23 and a Y-direction scanner drive signal 24 to the two-dimensional pyroelectric infrared detection element 2 based on the chopper rotation signal 26. In the two-dimensional pyroelectric infrared detection element 2, the Y-direction scanner 19 first designates one horizontal line, and turns on the plurality of read switches 22 in the designated horizontal line. Next, X-direction scanner 1
The output voltages of the plurality of pyroelectric sensors 21 in the horizontal line designated by 8 are sequentially output as the element output signal 25 via the built-in amplifier 20. Next, the external amplifier 6 outputs the element output signal 25
Is amplified and the external amplifier output signal 28 is output to the A / D converter 7. The A / D converter 7 A / D converts the external amplifier output signal 28 at the timing designated by the A / D conversion timing signal 27. FIG. 10 shows an example of the output timing of the output data 29 of the A / D converter by the scanning reading. In FIG. 10, S9 to S17 are effective pixels 9 to 1 respectively.
This is an output corresponding to 7. Chopper 3 as above
The output of the pyroelectric sensor 21 immediately before being closed is temporarily stored in the frame memory 8 as A / D converter output data 29, and then output as image data 30 at a desired timing.

[0004]

Since the conventional pyroelectric infrared imaging device is constructed as described above, the scanning switching noise of the X-direction scanner and the Y-direction scanner is superposed on the output voltage of the pyroelectric sensor. However, there is a problem that the S / N of the image is lowered.

The present invention has been made to solve the above-mentioned problems, and it is a pyroelectric type which can reduce a scan switching noise of an X-direction scanner and a Y-direction scanner and can obtain a clear image with a high S / N. An object is to obtain an infrared imaging device.

[0006]

A pyroelectric infrared imaging device according to the present invention comprises dummy pixels arranged in a line in a two-dimensional pyroelectric infrared detection element, and further includes a canceling data memory and a noise canceling circuit. Are provided between the A / D converter and the frame memory. A pyroelectric infrared imaging device according to another invention includes a dummy pixel, an X-direction dummy pixel scanner for scanning and reading the dummy pixel in synchronization with an X-direction scanner for scanning and reading an effective pixel, and An X-direction scanner and a differential amplifier which receives the output of the X-direction dummy pixel scanner as an input are provided in a two-dimensional pyroelectric infrared detection element. A pyroelectric infrared imaging device according to still another aspect of the invention includes dummy pixels arranged two-dimensionally, and scanning and reading of the dummy pixels in the X-direction scanner and the Y-direction.
It is provided with an X-direction dummy pixel scanner and a Y-direction dummy pixel scanner which are respectively synchronized with the direction scanner, a differential amplifier which receives the outputs of the X-direction scanner and the X-direction dummy pixel scanner.

[0007]

In the pyroelectric infrared imaging device according to the present invention, the scanning switching noise of the X-direction scanner output by the dummy pixel is stored in the cancellation data memory, and is subtracted from the output data of the effective pixel in the noise cancellation circuit. , Reduce scan switching noise. Further, in a pyroelectric infrared imaging device according to another invention, an X-direction dummy pixel scanner and an X-direction scanner scan dummy pixels and effective pixels in synchronization with each other, and scan switching noise output from the dummy pixels is eliminated. Noise is canceled by subtracting from the output of the effective pixel in the differential amplifier. In a pyroelectric infrared imaging device according to yet another invention, an X-direction dummy pixel scanner and a Y-direction dummy pixel scanner scan dummy pixels in synchronization with the X-direction scanner and the Y-direction scanner, respectively. The noise is canceled by subtracting the scanning switching noise output from the effective pixel output in the differential amplifier.

[0008]

EXAMPLES Example 1. FIG. 1 is a block diagram showing an embodiment of a pyroelectric infrared imaging device according to the present invention.
4, 6, 7, 8 and 26 are the same as those in the conventional embodiment. Reference numeral 31 is a two-dimensional pyroelectric infrared detecting element installed on the image plane of the infrared optical system, 32 is a timing generating circuit, 33 is a canceling data memory, and 34 is a noise canceling circuit. The cancellation data memory 33 and the noise cancellation circuit 34 are both the A / D converter 7
And the frame memory 8. Next, in FIG.
It is a block diagram of the three-dimensional pyroelectric infrared detection element 31. In the figure,
9 to 17 and 18, 20, 21, and 22 are the same as those in the conventional embodiment. 35, 36 and 37 are dummy pixels,
Each is composed of a dummy pyroelectric sensor 38 and a read switch 39. The dummy pyroelectric sensor 38 is shielded from incident infrared rays by, for example, vapor deposition of a metal film. Reference numeral 40 denotes a Y-direction scanner in which the number of scanning lines is increased by the number of dummy pixels as compared with the conventional Y-direction scanner. Next, the signals shown in FIGS. 1 and 2 will be described. 41 is an X-direction scanner drive signal, 42 is a Y-direction scanner drive signal, 43 is an element output signal, 44 is an external amplifier output signal, 45 is an A / D conversion timing signal, 46, 4
7 is offset noise data, 48 is image data before offset, 49,
Reference numeral 50 is post-offset image data.

Next, the operation of the pyroelectric infrared imaging device according to the present invention will be described. When the chopper 3 is rotated, the timing generator 32 causes the chopper rotation angle signal 2 to be generated as in the conventional case.
6, an X-direction scanner drive signal 41 and a Y-direction scanner drive signal 42 are generated and sent to the X-direction scanner 18 and the Y-direction scanner 40, and output voltages of the dummy pixels 35, 36, 37 and effective pixels 9 to 17 are generated. Are sequentially output as the element output 43 through the built-in amplifier 20, amplified by the external amplifier 6, and then A / D converted by the A / D converter 7. At this time, each of the pyroelectric sensors 21 in the effective pixels 9 to 17 of the two-dimensional pyroelectric infrared detection element 31 outputs a voltage in synchronization with the opening and closing of the chopper 3 in the same manner as in the conventional embodiment. Directional scanner 1
8 scanning switching noises are superimposed. On the other hand, the output voltage of each dummy pyroelectric sensor 38 in the dummy pixels 35, 36, 37 is only the scanning switching noise of the X-direction scanner 18. FIG. 3 is a diagram showing the timing relationship among the chopper rotation angle signal 26, the output voltage of the pyroelectric sensor 21, the cancellation noise data 46, the pre-cancellation image data 48, and the post-cancellation image data 49. In the figure, D35, D36, D37. Are outputs of the dummy pixels 35, 36 and 37, respectively, and S9 to S17 are outputs of the effective pixels 9 to 17, respectively. Above D35, D
36 and D37 are transferred to the offset data memory 33 as noise data 46 and stored therein. On the other hand, S9 to S17 are transferred as the pre-cancellation image data 48 to the noise cancellation circuit 34, and the noise cancellation circuit 34 performs noise cancellation based on the noise data 47 from the cancellation data memory 33, and outputs the post-cancellation image data 49. Output in the order shown in FIG.

Next, the offset image data 49 is stored in the frame memory 8 and output as the offset image data 50 at a desired display timing.

Embodiment 2. FIG. 4 is a diagram showing the configuration of a two-dimensional pyroelectric infrared detection element constituting a pyroelectric infrared imaging device according to another embodiment of the present invention. In the figure, 9 to 19 and 23 and 24 are the same as those in the conventional example. 51,
Reference numerals 52 and 53 denote dummy pixels, each of which includes a dummy pyroelectric sensor 54 and a read switch 55.
The gate of the read switch 55 is connected to the power supply terminal 56,
It is always fixed in the "on" state. Like the first embodiment, the dummy pyroelectric sensor 54 is shielded from the incident infrared rays. 57 is an X for scanning the dummy pixels 51, 52, 53
The directional dummy pixel scanner 58 is a differential amplifier which receives the outputs of the X-direction scanner 18 and the X-direction dummy pixel scanner 57 as inputs. Reference numeral 59 is an element output output from the differential amplifier 58. The configuration of the pyroelectric infrared imaging device is shown in FIG.
This is the same as the conventional example shown in FIG.

Next, the operation will be described. Operation of the effective pixels 9 to 17 by opening and closing the chopper 3, X-direction scanner 1
The operations of the 8 and Y-direction scanners 19 are the same as those in the conventional embodiment, and the X-direction scanner 18 outputs a signal in which scanning switching noise is superimposed on the output due to the energy of the radiated infrared light from the imaged object. On the other hand, the dummy pyroelectric sensor 5
As in the first embodiment, infrared rays do not enter 4 and the read switch 55 is always "on". Therefore, the X-direction dummy pixel scanner 57 outputs only scan switching noise.
The differential amplifier 58 outputs the difference between the output of the X-direction dummy pixel scanner 57 and the output of the X-direction scanner 18 as an element output 59. FIG. 5 is a diagram showing the contents and output order of the element output 59. In the figure, S9 to S17 are outputs of the effective pixels 9 to 17, and D51, D52, and D53 are outputs of the dummy pixels 51, 52, and 53, respectively. is there. Since the X-direction dummy pixel scanner 57 operates in synchronization with the X-direction scanner 18, the scanning switching noise of both is also synchronized and canceled by the differential amplifier 58.

Embodiment 3. FIG. 6 is a diagram showing the configuration of a two-dimensional pyroelectric infrared detection element constituting a pyroelectric infrared imaging device according to another embodiment. In the figure, 9 to 19, 23, 2
Reference numerals 4 and 58 are the same as those in the conventional embodiment. 60-68
Are dummy pixels arranged geometrically the same as the effective pixels, and the respective configurations are the same as the dummy pixels 35 of the first embodiment. Reference numeral 69 is an X-direction dummy pixel scanner, and reference numeral 70 is a Y-direction dummy pixel scanner, to which the same X-direction scanner drive signal 23 and Y-direction scanner drive signal 24 as those of the X-direction scanner 18 and the Y-direction scanner 19 are applied, respectively. Reference numeral 58 is a differential amplifier that receives the outputs of the X-direction scanner 18 and the X-direction dummy pixel scanner 69 as inputs. Reference numeral 71 is an element output output from the differential amplifier 58. The structure of the pyroelectric infrared imaging device is the same as that of the conventional embodiment shown in FIG.

Next, the operation will be described. Chopper 3
The operations of the effective pixels 9 to 17 and the operations of the X-direction scanner 18 and the Y-direction scanner 19 by opening and closing are the same as those of the conventional embodiment. It outputs a signal on which switching noise is superimposed. On the other hand, the dummy pixels 60 to 6
Infrared rays do not enter 8 as in the first embodiment, and the X-direction dummy pixel scanner 69 outputs scanning switching noise in which the scanning switching noises of the X-direction dummy pixel scanner 69 and the Y-direction dummy pixel scanner 70 are superimposed. The differential amplifier 58 outputs the difference between the output of the X-direction scanner 18 and the output of the X-direction dummy pixel scanner 69 as an element output 71. FIG. 7 is a diagram showing the contents and output order of the element output 71. In the figure, S9 to S17 are the effective pixels 9 to
17 is the output of Dummy pixel D60 to D68
~ 68 outputs. X-direction dummy pixel scanner 69,
Since the Y-direction dummy pixel scanner 70 operates in synchronization with the X-direction scanner 18 and the Y-direction scanner 19, respectively.
The scanning switching noise output from the X-direction scanner 18 and the scanning switching noise output from the X-direction dummy pixel scanner 69 are synchronized and canceled by the differential amplifier 58.

[0015]

As described above, according to the present invention, the scanning switching noise of the X-direction scanner is canceled and S / S is reduced.
There is an effect that a clear image with high N can be obtained. Further, according to another invention, since the canceling data memory and the noise canceling circuit can be omitted, the scan switching noise of the X-direction scanner can be canceled without increasing the size of the apparatus, and a clear image with high S / N can be obtained. effective. Further, according to still another aspect of the invention, the scanning switching noises of the X-direction scanner and the Y-direction scanner can be canceled out without enlarging the apparatus, and a clear image with high S / N can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of a pyroelectric infrared imaging device according to the present invention.

FIG. 2 is a diagram showing a configuration of a two-dimensional pyroelectric infrared detection element of the pyroelectric infrared imaging device according to the present invention.

FIG. 3 is a diagram for explaining an example of the operation of the pyroelectric infrared imaging device according to the present invention.

FIG. 4 is a diagram showing a configuration of a two-dimensional pyroelectric infrared detection element of a pyroelectric infrared imaging device according to another embodiment of the present invention.

FIG. 5 is a diagram for explaining the contents and order of element outputs of a two-dimensional pyroelectric infrared detection element of a pyroelectric infrared imaging device according to another embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a two-dimensional pyroelectric infrared detection element of a pyroelectric infrared imaging device according to still another embodiment.

FIG. 7 is a diagram illustrating the content and order of element outputs of a two-dimensional pyroelectric infrared detection element of a pyroelectric infrared imaging device according to yet another embodiment.

FIG. 8 is a diagram showing a configuration of an example of a conventional pyroelectric infrared imaging device.

FIG. 9 is a diagram showing a configuration of a two-dimensional pyroelectric infrared detection element of a conventional pyroelectric infrared imaging device.

FIG. 10 is a diagram illustrating an operation of a conventional pyroelectric infrared imaging device.

[Explanation of symbols]

 1 Infrared Optical System 3 Chopper 4 Chopper Rotation Angle Detection Means 6 External Amplifier 7 A / D Converter 8 Frame Memory 9 Effective Pixel 10 Effective Pixel 11 Effective Pixel 12 Effective Pixel 13 Effective Pixel 14 Effective Pixel 15 Effective Pixel 16 Effective Pixel 17 Effective Pixels 18 X-Direction Scanner 19 Y-Direction Scanner 31 Two-Dimensional Pyroelectric Infrared Detector 32 Timing Generation Circuit 33 Offset Data Memory 34 Noise Cancellation Circuit 35 Dummy Pixel 36 Dummy Pixel 37 Dummy Pixel 40 Y-Direction Scanner 51 Dummy Pixel 52 Dummy Pixel 53 Dummy pixel 57 X direction dummy pixel scanner 58 Differential amplifier 60 Dummy pixel 61 Dummy pixel 62 Dummy pixel 63 Dummy pixel 64 Dummy pixel 65 Dummy pixel 66 Dummy pixel 67 Dummy pixel 68 Dummy pixel 69 X direction dummy pixel scan NA 70 X direction dummy pixel scanner

Claims (3)

[Claims] 1. An infrared optical system, a two-dimensional pyroelectric infrared detecting element installed on an image plane of the infrared optical system, the infrared optical system and the two-dimensional pyroelectric infrared detecting element. A chopper disposed between the chopper, a chopper rotation angle detecting means attached to the chopper, an external amplifier for amplifying the output of the two-dimensional pyroelectric infrared detecting element, and an output of the external amplifier by A
Based on the outputs of the A / D converter for A / D conversion and the chopper rotation angle detecting means, the timing of scanning and reading of the two-dimensional pyroelectric infrared detecting element and the conversion timing of the A / D converter are generated. A timing generation circuit, a cancellation data memory for storing output data of the A / D converter,
The noise canceling circuit for subtracting the stored data of the canceling data memory from the output data of the D / D converter and the frame memory for storing the output of the noise canceling circuit are provided, and the two-dimensional pyroelectric infrared detecting element is Pyroelectric infrared imaging comprising: effective pixels arranged in a dimension; dummy pixels arranged in a line; and an X-direction scanner and a Y-direction scanner for scanning and reading the effective pixels and dummy pixels. apparatus. 2. An infrared optical system, a two-dimensional pyroelectric infrared detecting element installed on an image plane of the infrared optical system, the infrared optical system and the two-dimensional pyroelectric infrared detecting element. A chopper disposed between the chopper, a chopper rotation angle detecting means attached to the chopper, an external amplifier for amplifying the output of the two-dimensional pyroelectric infrared detecting element, and an output of the external amplifier by A
Based on the outputs of the A / D converter for A / D conversion and the chopper rotation angle detecting means, the timing of scanning and reading of the two-dimensional pyroelectric infrared detecting element and the conversion timing of the A / D converter are generated. The two-dimensional pyroelectric infrared detection element includes a timing generation circuit and a frame memory for storing the output of the A / D converter, and the two-dimensional pyroelectric infrared detection element scans and reads out the effective pixels and the effective pixels. X-direction scanner, Y-direction scanner, dummy pixels arranged in a line, X-direction dummy pixel scanner for scanning and reading the dummy pixels in synchronization with the X-direction scanner, X-direction scanner and X-direction dummy pixel A pyroelectric infrared imaging device comprising: a differential amplifier that receives an output of a scanner. 3. An infrared optical system, a two-dimensional pyroelectric infrared detecting element installed on an image plane of the infrared optical system, the infrared optical system and the two-dimensional pyroelectric infrared detecting element. A chopper disposed between the chopper, a chopper rotation angle detecting means attached to the chopper, an external amplifier for amplifying the output of the two-dimensional pyroelectric infrared detecting element, and an output of the external amplifier by A
Based on the outputs of the A / D converter for A / D conversion and the chopper rotation angle detecting means, the timing of scanning and reading of the two-dimensional pyroelectric infrared detecting element and the conversion timing of the A / D converter are generated. The two-dimensional pyroelectric infrared detection element includes a timing generation circuit and a frame memory for storing the output of the A / D converter, and the two-dimensional pyroelectric infrared detection element scans and reads out the effective pixels and the effective pixels. X-direction scanner, Y-direction scanner, two-dimensional array of dummy pixels,
Input the outputs of the X-direction dummy pixel scanner, the Y-direction dummy pixel scanner, the X-direction scanner, and the X-direction dummy pixel scanner, which perform scanning reading of the dummy pixels in synchronization with the X-direction scanner and the Y-direction scanner, respectively. A pyroelectric infrared imaging device, comprising: