JPH0321888A - Pyroelectric type infrared detecting device - Google Patents

Abstract

PURPOSE:To improve space resolution characteristics by scanning an infrared-ray image in order by X-axial movement on a pyroelectric element array where unit pyroelectric elements are arranged electrically in series in an X-axial and a Y-axial direction so that adjacent elements generate counter electromotive forces. CONSTITUTION:The 8X8 unit pyroelectric elements which are arranged in X-Y matrix constitute two blocks of 4X8 unit pyroelectric elements which are symmetrical in the X-axial direction about an upper ground electrode 4 formed in the Y-axial direction at the center part of the matrix. Four X-axial unit pyroelectric elements are arranged alternately in the patterns of electrodes 2 and 3 and unit pyroelectric elements which are arranged in array are connected electrically in series. Eight pyroelectric element arrays are provided in the Y-axial direction. The lengths in the X-axial and Y-axial directions are equalized to the length of the unit pyroelectric elements and an optical unit 5 which has an opening part is provided in each block. Then the X-axial movement is performed on the front surface of the pyroelectric element array to scan the incident infrared-ray image and voltages developed between signal lead-out electrodes 6 and 7 and electrode 4 are supplied as output signals to a signal processing circuit.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a pyroelectric infrared detection device that detects the position of an object using a pyroelectric infrared sensor. Devices that use infrared sensors to detect the location of infrared sources have come into use for the purpose of crime prevention and disaster prevention, such as discovery.Infrared sensors include quantum type sensors using compound semiconductors and pyroelectric elements. Is it a thermal type using a thermistor or the like? 60 i
Although thermal infrared sensors are used for purposes such as crime prevention and disaster prevention, pyroelectric sensors are particularly sensitive compared to other thermal sensors. It has high sensitivity and is ideal for position detection devices for infrared sources. A slit is formed in front of a two-dimensional pyroelectric element array consisting of a plurality of pyroelectric element arrays connected in series and arranged in one row according to the electrode pattern.
A focusing system based on a novel operating principle that scans the infrared image incident on the pyroelectric element array by moving it in the axial direction, and reads out the voltage that is generated in time series between the electrodes at both ends of each row as the sensor output. Problems to be solved by the invention by proposing an electric type two-dimensional infrared detector If the number of unit pyroelectric elements included in a series of pyroelectric elements connected in series is N, and the sensor voltage generated in one unit pyroelectric element is V, then under a constant frame frequency ( The voltage that is the sensor output that occurs sequentially in time series between the electrodes at both ends of the column is V/N.
The disadvantage of the present invention is that the temperature resolution is reduced.
The purpose of this invention is to solve the problems of the prior art.

Means for Solving the Problems The present invention is characterized in that in a two-dimensional pyroelectric element array in which a plurality of unit pyroelectric elements are arranged in an X-Y matrix, each unit pyroelectric element is electrically connected in series and A pyroelectric element array configured by arranging a plurality of l pyroelectric element rows in the Y-axis direction and wired in the X-axis direction so that adjacent unit pyroelectric elements generate a back electromotive force, and the pyroelectric element It moves in the X-axis direction on the array and sequentially scans the infrared image irradiated to each pyroelectric element.The length in the X-axis direction is approximately equal to the length in the X-axis direction of the unit pyroelectric element, and the length in the Y-axis direction is composed of an optical slit having an opening approximately equal to the length in the Y-axis direction of all the unit pyroelectric elements arranged in the Y-axis direction, and a plurality of the blocks arranged in the X-axis direction also works. The present invention It is a two-dimensional pyroelectric element in which the number of unit pyroelectric elements included in a series of pyroelectric element arrays connected in series in the X-axis direction is fixed to a number (n) that satisfies the required temperature resolution. When a block is constructed, the sensor output voltage that is generated sequentially in time series between the electrodes at both ends in the α and χ axis directions within this block is V/n.This two-dimensional pyroelectric element block is divided into m pieces in the X-axis direction. Connection L, even if the total number of pixels in the X-axis direction is nxm = N, the sensor output voltage is maintained at V/n in each block, so there is no decrease in temperature resolution. In the following, embodiments of the present invention will be explained with reference to the drawings. Fig. 1 is a plan view of an embodiment of the pyroelectric infrared detection device of the present invention (Fig. ), a cross-sectional view (Figure (B)), and an equivalent circuit (Figure (C)). An upper electrode 2 and a lower electrode 3 are formed on both sides of the pyroelectric thin film 1, respectively, to constitute each pyroelectric element. 8 x 8 pyroelectric elements arranged in an X-Y matrix (with the upper ground electrode 4 formed in the Y-axis direction in the center of the matrix as the symmetrical axis, each 4 x 8 pyroelectric element is symmetrical in the X-axis direction). Even if the four unit pyroelectric elements in the X-axis direction in each block are arranged in two blocks, the adjacent four unit pyroelectric elements are alternately wired according to the pattern of the electrodes 2.3 and arranged in a line. The unit pyroelectric elements are electrically connected in series to form a pyroelectric element row, and the eight pyroelectric element rows are arranged in the Y-axis direction, and the length in the X-axis direction is equal to Y approximately equal to the length in the X-axis direction
One optical slit 5 having an opening whose axial length is approximately equal to the length in the Y-axis direction of all the unit pyroelectric elements arranged in the Y-axis direction is provided in each block. By moving the front surface of the pyroelectric element array in the X-axis direction, the infrared image incident on the pyroelectric element array is scanned.
In each block, even if the voltage generated between the left and right signal extraction electrodes 6, 7 provided at the ends of each column and the upper ground electrode 4 is connected to the signal processing circuit as an output signal, the left block If we pay attention to the unit pyroelectric element 8 that is irradiated with infrared rays in any arbitrary pyroelectric element array, we can see that this unit pyroelectric element generates a signal voltage V that corresponds to the intensity of the infrared rays.
No voltage is generated in other unit pyroelectric elements in the same pyroelectric element array that are not irradiated with infrared rays.This is equivalent to connecting a capacitor in series with unit pyroelectric element 8.A signal with a sufficiently high input impedance When the processing circuit is connected, the output signal appearing at the signal extraction electrode 6 is the sum of the outputs of each pyroelectric element.In other words, the output voltage is equal to the voltage V generated in the unit pyroelectric element 8. A voltage force exchange proportional to the amount of infrared rays irradiated to the pyroelectric element at each vehicle position is sequentially output to the signal extraction electrode 6. Similarly, the unit focal point irradiated with infrared rays in any pyroelectric element row in the right block is The output signal of the electric element 9 also appears on the signal extraction electrode 7. In other words, in this method (by dividing the two-dimensional pyroelectric element array into two blocks, the same focus can be achieved with one scan of the optical slit 5). The output signals from two unit pyroelectric elements in the electric element array can be extracted simultaneously.This allows the number of pixels of the sensor to be doubled without reducing the temperature resolution under a constant frame frequency. Although it is possible, the optical slit 5ζ used here may have two opening grooves corresponding to the left and right blocks on one substrate and move in conjunction within the left and right blocks, or it may be separated. The two optical slits may move independently within the left and right blocks ( Although it is of course possible to divide the force into a larger number of units, the present invention improves the spatial resolution by increasing the number of pixels of the sensor without reducing the temperature resolution under a constant frame frequency. Although it is possible to easily realize a pyroelectric infrared detector equipped with a two-dimensional pyroelectric element array,

[Brief explanation of drawings]

The planes shown in Figures 1 (A), (B), and (C)i, each showing a pyroelectric infrared detector according to an embodiment of the present invention, are equivalent circuits in cross section.

Claims (2)

[Claims] (1) In a pyroelectric infrared detection device with a two-dimensional pyroelectric element array in which a plurality of unit pyroelectric elements are arranged in an A pyroelectric element array configured by arranging a plurality of pyroelectric element rows in the Y-axis direction and wired in the X-axis direction so that adjacent unit pyroelectric elements generate a back electromotive force, and the pyroelectric element A device whose length in the X-axis direction is approximately equal to the length of the unit pyroelectric element in the X-axis direction, which moves in the X-axis direction on the array and sequentially scans the infrared image irradiated to each pyroelectric element. an optical slit having an opening whose length is approximately equal to the length in the Y-axis direction of all the unit pyroelectric elements arranged in the Y-axis direction, and a plurality of the blocks are arranged in the X-axis direction. A pyroelectric infrared detection device featuring: (2) Construct two blocks consisting of a plurality of unit pyroelectric elements that are symmetrical in the X-axis direction, with the ground electrode formed in the Y-axis direction at the center of the matrix as the symmetrical axis, and the X-axis direction within each block The unit pyroelectric elements are alternately wired adjacent to each other by electrode patterns to form a pyroelectric element row that is electrically connected in series, and a plurality of the pyroelectric element rows are arranged in the Y-axis direction, The pyroelectric infrared detection device according to claim 1, wherein in the block, a voltage generated between a signal extraction electrode provided at an end of each pyroelectric element row and the ground electrode is read out as an output signal. .