JP2006170930A - Infrared detection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an infrared detection apparatus capable of highly precisely acquiring output signals of infrared detection elements without being affected by switching noise which occurs when scanning is selected. <P>SOLUTION: The infrared detection apparatus is provided with a first scanning means (N-type MOSFET switches M11-Mmn) for selecting the vertical scanning of output signals of infrared detection elements of two-dimensional infrared detection element blocks 11-1k; horizontal scanners 51-5k for selecting horizontal scanning of output signals selected by the scanning means and outputting them; and a block scanner 8 for selecting the scanning of output of the horizontal scanners 51-5k and outputting it. The scanning of the horizontal scanner 51 is started after a delay of T3 from the selection of one column by the first scanning means, and the scanning of the horizontal scanner 5i is started after a delay of T3 from the starting of the scanning of the horizontal scanner 5(i-1) (wherein, i is an integer of ≥2 and ≤k; and the time during which the block scanner 8 has selected one signal is T3). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an infrared detection device.

  In recent years, there is a strong demand for imaging the temperature distribution of a subject in real time, and the demand for two-dimensional infrared detection devices is increasing. Accordingly, development of an inexpensive and high-performance infrared detector is desired.

  In the following Patent Document 1, in order to cope with multi-pixel and high-speed scanning, pixels arranged two-dimensionally are divided into blocks in the horizontal direction, and pixel signals selected for scanning are read out in units of blocks (in parallel) ( Although a solid-state imaging device is described, it is not described until the outputs for each block are combined into one.

JP 2001-223947 A

  Infrared detectors that measure the temperature rise due to absorption of incident infrared rays are used. In addition, in infrared detectors that employ horizontal block division, a thermopile or the like is used to measure the temperature rise. When a high output impedance is used, there is a problem that switching noise generated at the time of switching in the vertical direction is superimposed on an output signal of an infrared detection element that is selected for scanning immediately after switching.

  In order to accurately extract the output signal of the infrared detection element, the output signal is extracted by sampling with an A / D converter in the period after the influence of the switching noise is eliminated. Since it is necessary to take a long time to scan and select one pixel, there is a problem that, for example, it is difficult to image a temperature distribution of a subject at high speed.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an infrared detection device capable of obtaining a highly accurate infrared detection element output signal without being affected by switching noise generated at the time of scanning selection. Is to provide.

  Infrared detectors arranged in the same row of the infrared detectors in which k two-dimensional infrared detector blocks each having a plurality of infrared detectors arranged in a matrix of m rows and n columns are arranged in one row. The first scanning means for scanning and selecting the output signal from the first row to the m-th row, and the output signal of the infrared detection element selected by scanning by the first scanning means for each two-dimensional infrared detection element block In addition, k second scanning means for scanning and outputting from the first column to the n-th column, and the output signal of the second scanning means from the first second scanning means to the kth Block scanning means for selecting and outputting the scanning up to the second scanning means, and the time when the output signals of the infrared detection elements arranged in one row by the first scanning means are selected is T1, and the second scanning means One infrared detection element is In the infrared detection device where T1> T2> T3, where T2 is the time when the signal is selected and T3 is the time when the output signal of one second scanning means is selected by the block scanning means, i Is an integer equal to or greater than 2 and equal to or less than k, the output of the infrared detecting element by the first second scanning unit is delayed by T3 from the time when the selection of the row by the first scanning unit is switched to the selection of the next row. Infrared detecting element by the i-th second scanning means is delayed by T3 from the time when scanning selection of the signal is started and the scanning selection of the output signal of the infrared detecting element by the (i-1) -th second scanning means is started. The infrared detection apparatus is characterized in that the scanning selection of the output signal is started.

  By implementing the present invention, it is possible to provide an infrared detection device that can obtain an infrared detection element output signal with high accuracy without being affected by switching noise generated when scanning is selected.

  The present invention relates to an infrared detection device that detects a two-dimensional infrared intensity distribution using a plurality of infrared detection elements that convert incident infrared light into an electrical signal, for example, an infrared detection device that images a temperature distribution of a subject, More specifically, the present invention relates to a technique for imaging a temperature distribution of a subject at high speed and with high accuracy.

  Hereinafter, embodiments of the present invention will be described. FIG. 1 is a circuit configuration diagram illustrating an infrared detection device according to an embodiment of the present invention.

  In FIG. 1, 11 to 1k (here, k is an integer of 2 or more) is a two-dimensional infrared detection element block, 2 is a counter, 3 is a vertical decoder, 41 to 4k is a horizontal decoder, and 51 to 5k are A horizontal scanner, 61 to 6k are differential amplifiers, 7 is a block decoder, and 8 is a block scanner.

  In addition, as a representative of the two-dimensional infrared detection element block 11 to 1k and the horizontal scanner 51 to 5k, the detailed circuit of the two-dimensional infrared detection element block 11 and the horizontal scanner 51 is shown in FIG. The two-dimensional infrared detection element blocks 12 to 1k are the same circuit as the two-dimensional infrared detection element block 11, and the horizontal scanners 52 to 5k are the same circuits as the horizontal scanner 51, respectively.

  Each of the two-dimensional infrared detection element blocks 11 to 1k has m and n as integers of 2 or more, and m rows having m columns in the vertical direction as the first direction and n columns in the horizontal direction as the second direction. Infrared detection elements (represented as a series circuit of a resistor and a voltage source in the figure) arranged in a matrix of n columns. The two-dimensional infrared detection element blocks 11 to 1k are arranged in a row in the horizontal direction, which is the second direction, and thereby an infrared detection unit is configured.

  The N-type MOSFET switches M11 to Mmn in the pixels 11 to mn receive the output signals of the infrared detectors arranged in the same row in the order from the first row to the mth row, using the output of the vertical decoder 3 as an input. The first scanning means for scanning selection.

  The horizontal scanners 51 to 5k correspond one-to-one with the two-dimensional infrared detection element blocks 11 to 1k, and the infrared detection is performed by the first scanning means in the corresponding two-dimensional infrared detection element block. There are k second scanning means for scanning and outputting the output signals of the elements in the order from the first column to the n-th column.

  The block scanner 8 is block scanning means for selecting and outputting the output signals of the horizontal scanners 51 to 5k as the second scanning means in order from the horizontal scanner 51 to the horizontal scanner 5k. .

  The differential amplifiers 61 to 6k serve as impedance conversion means interposed between the horizontal scanners 51 to 5k as second scanning means and the block scanner 8 as block scanning means. The outputs of the horizontal scanners 51 to 5k as the means are impedance-converted by the differential amplifiers 61 to 6k and input to the block scanner 8 as the block scanning means.

  Since the output signal of the infrared detection element is obtained by superimposing an electromotive voltage corresponding to the intensity of the incident infrared ray on the reference voltage Vref, the difference between the output signal of the infrared detection element and the differential amplification compared with Vref is output. From the dynamic amplifiers 61 to 6 k, an electromotive voltage corresponding to the intensity of incident infrared light incident on each infrared detection element is amplified and output.

  Here, assuming that a thermopile (a plurality of thermocouples connected so that the thermoelectromotive forces are combined in series) is assumed as the infrared detection element, as an equivalent circuit, as shown in FIG. It can be expressed as a series circuit.

  The two-dimensional infrared detection element block 11 in which infrared detection elements are arranged in m rows in the vertical direction and n columns in the horizontal direction has N-type MOSFET switches M11 to M1n, M21 to M2n,. ... To Mmn are connected to each infrared detection element, and similarly, N-type MOSFET switches M1 to Mn are connected to the horizontal scanner 51 for each infrared detection element array.

  Although the above configuration is also found in the conventional example, one of the differences of the present embodiment from the conventional example is that the following delay circuit is used. That is, in FIG. 1, reference numerals 91 to 9k denote delay circuits, which delay an input signal for a predetermined time and output it. The effects of the present invention can be obtained by installing the delay circuits 91 to 9k.

  FIG. 2 shows time charts of the output waveforms of the vertical decoder 3 and the horizontal decoder 41, the scan selection pixels in the two-dimensional infrared detection element block 11, and the output voltage Vp1 of the differential amplifier 61. FIG. , Scanning selection pixels in the respective two-dimensional infrared detection element blocks 11 to 1k, output voltages Vp1 to Vpk of the differential amplifiers 61 to 6k, output waveforms (Z1 to Zk) of the block decoder 7, scanning selection blocks, and The respective time charts of the output voltage Vout of the block scanner 8 are shown.

  The operation of the infrared detection device of the present invention will be described with reference to FIGS.

  First, the counter 2 counts the address based on the input reference clock CLK and outputs it to the vertical decoder 3, the delay circuit 91, and the block decoder 7.

  In the vertical direction decoder 3 and the block decoder 7, the address count from the counter 2 is decoded, and the vertical direction selection signals Y1 to Yk are used as the vertical direction selection signals Y1 to Ym for each row or the block selection signals Z1 to Zk for each block. Ym is a vertical scanner in the two-dimensional infrared detection element blocks 11 to 1k (gate terminals of N-type MOSFET switches M11 to Mmn of each two-dimensional infrared detection element block), and block selection signal signals Z1 to Zk are to the block scanner 8. Each is applied.

  As is apparent from FIGS. 2 and 3, the time during which the output signals of the infrared detection elements arranged in one row are selected by the first scanning means (N-type MOSFET switches M11 to Mmn) is defined as T1. The time during which the output signal of one infrared detecting element is selected by the horizontal scanners 51 to 5k which are the scanning means is T2, and the output signal of one horizontal scanner 51 to 5k is given by the block scanner 8 which is the block scanning means. T1> T2> T3, where T3 is the time during which T is selected.

  In the delay circuit 91, the horizontal address count from the counter 2 is delayed by one period (T 3) of the block scanning selection period, sent to the horizontal decoder 41 and sent to the delay circuit 92. In the delay circuit 92, the address count from the delay circuit 91 is delayed by one period (T 3) of the block scanning selection period, sent to the horizontal decoder 42 and sent to the delay circuit 93. Similarly, the address count input by the delay circuits 93 to 9 (k-1) is delayed by one period (T3) of the block scanning selection period and sent to the subsequent horizontal decoder and delay circuit, and finally The delay circuit 9k delays the address count from the delay circuit 9 (k-1) by one period (T3) of the block scanning selection period, and sends it to the horizontal decoder 4k. In this case, similarly to the conventional example, it is necessary that T2 ≧ k × T3, and FIG. 3 shows a case where T2 = k × T3.

  In the horizontal direction decoders 41 to 4k, the address counts from the delay circuits 91 to 9k are decoded and applied to the horizontal direction scanners 51 to 5k as a horizontal direction selection signal for each column. The horizontal address count number (cycle) is n + 1 count (cycle) which is one count (cycle) larger than the horizontal pixel number n of each of the two-dimensional infrared detection element blocks 11 to 1k. The horizontal address count number may be greater than n + 1. That is, in this case, T1 = (n + 1) T2 and T1> (n + 1) T2.

  By using the above configuration, when i is an integer of 2 or more and k or less, the selection of the row by the N-type MOSFET switches M11 to Mmn as the first scanning means is switched to the selection of the next row. After a delay of T3, scanning selection of the output signal of the infrared detection element by the horizontal scanner 51 as the first second scanning means is started, and the horizontal scanner 5 (the i−1th second scanning means) ( The scanning of the output signal of the infrared detection element by the horizontal scanner 5i which is the i-th second scanning means is delayed by T3 from the time when the scanning selection of the output signal of the infrared detection element in i-1) is started. Selection can be initiated. Here, “when the row selection is switched to the selection of the next row” means that the output signals of the infrared detection elements arranged in one row are the output signals of the infrared detection elements arranged in the next row. It means the point of time when the transition to selection.

  Here, the pixel scanning selection operation will be described by taking the two-dimensional infrared detection element block 11 as an example. As shown in the time chart of FIG. 2, when the vertical direction selection signals Y1 to Ym or the horizontal direction selection signals X1 to Xn become H (high) level, the connected N-type MOSFET switches are turned on (conductive). As a result, first, when the vertical direction selection signal Y1 becomes H level, the N-type MOSFET switches M11 to M1n are turned on, and the infrared detection element output signals of the pixels 11 to 1n are sent to the horizontal scanner 51 as V1 to Vn.

  Thereafter, when one time (T3) of the block scanning selection period elapses, the horizontal direction selection signal X1 becomes H level, the N-type MOSFET switch M1 is turned on, and the output of the horizontal scanner 51 includes a pixel. 11 is scanned and selected, and the differential amplifier 61 amplifies an electromotive voltage corresponding to the intensity of the incident infrared rays of the infrared detection element of the pixel 11 and outputs the amplified voltage as a voltage Vp1.

  Thereafter, the horizontal direction selection signals X2 to Xn sequentially become H level, and the output voltage Vp1 of the differential amplifier 61 is scanned with the infrared detection element output signals of the pixels 12 to 1n following the infrared detection element output signals of the pixels 11. Selected.

  After the infrared detection element output signal of the pixel 1n is selected for scanning, a selected selection signal (any one is acceptable in the horizontal direction selection signals X1 to Xn, hereinafter referred to as X3 as an example) becomes H level. The pixel (pixel 13) corresponding to the selection signal (X3) in the pixels 11 to 1n is selected again.

  Next, when the vertical direction selection signal Y2 becomes H level, the N-type MOSFET switches M21 to M2n are turned on, and the infrared detection element output signals of the pixels 21 to 2n are sent to the horizontal scanner 51 as V1 to Vn. At this time, since the horizontal direction selection signal remains the selection signal (X3) immediately before the vertical direction selection signal Y2 becomes H level, the pixel corresponding to the selection signal (X3) in the pixels 21 to 2n ( Pixel 23) will be selected.

  Thereafter, when the time (T3) for one block scanning selection period elapses, the horizontal direction selection signal X1 becomes H level, the N-type MOSFET switch M1 is turned on, and the output of the horizontal direction scanner 51 includes a pixel. The infrared detection element output signal 21 is scanned and selected, and the electromotive voltage of the infrared detection element of the pixel 21 is amplified by the differential amplifier 61 and is output as the voltage Vp1.

  Thereafter, the horizontal direction selection signals X2 to Xn sequentially become H level, and the output voltage Vp1 of the differential amplifier 61 is scanned with the infrared detection element output signals of the pixels 22 to 2n following the infrared detection element output signals of the pixels 21. Selected. After the infrared detection element output signal of the pixel 2n is selected for scanning, the selected selection signal (X3) in the horizontal direction selection signals X1 to Xn becomes H level, and the above-mentioned selection signals in the pixels 21 to 2n The pixel (pixel 31) corresponding to the selection signal (X3) is selected again.

  Therefore, by repeating these operations, the output voltage Vp1 of the differential amplifier 61 is applied to the pixels 11 to 1n, the pixels 1 * and 2 *, the pixels 21 to 2n, the pixels 2 * and 3 *,. Scan selection is performed in the order of the pixel mn, the pixel m *, and the pixel 1 *, and the scan selection from the pixel 11 is repeated again (* is a predetermined number in 1 to n, which is 3 here).

  Through the above operation, as shown in the time chart of FIG. 3, the signals selected by the two-dimensional infrared detection element blocks 11 to 1k and output through the differential amplifiers 61 to 6k are scanned in the vertical direction. With the selection switching point as a reference, the two-dimensional infrared detection element block 11 has one block scanning selection period (T3), and the two-dimensional infrared detection element block 12 has two block scanning selection periods (2 × T3). Similarly, in the two-dimensional infrared detection element block 1k, the scanning selection pixel is switched at a timing at which k periods (k × T3) of the block scanning selection period are delayed.

  The block selection signals Z1 to Zk sequentially become H level with reference to the switching point of the vertical scanning selection (row scanning selection), so that the output voltage Vout of the block scanner 8 includes, for example, 1 in the vertical direction. When the scanning selection is switched to the row, scanning is selected in the order of pixel 1 * of block 11, pixel 1 * of block 12,..., Pixel 1 * of block 1k, and then pixel 11 of block 11 and pixel of block 12 11,..., Block 1k, pixel 11, block 11 pixel 12, block 12 pixel 12,..., Block 1k pixel 12,..., Block 11 pixel 1n, block 12 pixel 1n,. Next, the scanning selection is switched to the second row in the vertical direction. By repeating these series of operations, the infrared detection element output signals of all the pixels of the two-dimensional infrared detection element block are selected for scanning.

  Incidentally, immediately after the selection of the row by the first scanning means (N-type MOSFET switches M11 to Mmn) is switched to the selection of the next row, that is, the output signals of the infrared detecting elements arranged in one row by this scanning means. A signal output for one cycle period of the block scanning selection immediately after the selection of the output signal of the infrared detection element arranged in the next row is shifted, for example, scanning selection switching to the first row in the vertical direction is considered. Since each pixel 1 * signal of the two-dimensional infrared detection element blocks 11 to 1k immediately after switching is affected by switching noise generated when switching scanning in the vertical direction, for example, the temperature of the subject The output signal of the infrared detection element from the pixel 11 of the block 11 to the pixel 1n of the block 1k that is not used as data obtained by imaging the distribution and is selected after that. , For example, to use as the data of the captured temperature distribution of the subject. That is, the output signals of the horizontal scanners 51 to 5k which are the second scanning means immediately after the selection of the row by the first scanning means (N-type MOSFET switches M11 to Mmn) is switched to the selection of the next row, It is not handled as an electrical signal according to the intensity of incident infrared rays.

  In the following, similarly for other vertical scanning selection switching, the signal output for one cycle period of the block scanning selection immediately after the switching of the scanning selection is not used, and the infrared detection element output signal that is selected for scanning after this is used. Is used as data obtained by imaging the temperature distribution of the subject, for example.

  As a result, for example, the scanning selection by the block scanner 8 within the period used as the imaging data of the subject temperature distribution is the two-dimensional infrared ray for any pixel scanning selection of any two-dimensional infrared detection element block. At the timing immediately before the horizontal scanning selection in the detection element block is switched to the next pixel, the block scanning selection of the two-dimensional infrared detection element block is made and taken out as the final output, and the two-dimensional infrared detection is performed. Since the outputs of the elementary blocks 11 to 1k are impedance-converted by the differential amplifiers 61 to 6k, switching noise is not superimposed on the output Vout of the block scanner 8. Therefore, even in the case where switching noise is generated immediately after switching of horizontal scanning selection with an infrared detection element having a high output impedance such as a thermopile (thermocouple), it is affected by this switching noise. The pixel signal can be selected without scanning.

  As described above, according to the embodiment of the present invention, the two-dimensional infrared detection element block that is first scanned and selected by the block scanner 8 is used as the horizontal direction selection signal input to each of the two-dimensional infrared detection element blocks 11 to 1k. Since the horizontal direction selection signal input to 11 is used as a time reference, one block (T3) of the block scanning selection period is added as a delay time in the order of the two-dimensional infrared detection element block selected for scanning. A highly accurate infrared detection element output signal can be obtained without being affected by switching noise generated at the time of scanning selection. For example, the temperature distribution of the subject can be imaged at high speed.

  The signal cycle of the horizontal direction selection signal (vertical direction scanning selection period, T1) is not less than n + 1 times the signal period of the block selection signal (horizontal direction scanning selection period, T2) (n is the number of infrared detection element arrays in the horizontal direction). In the period of the horizontal direction selection signal period excluding the first horizontal direction scanning selection period immediately after the switching of the vertical direction scanning selection, all the infrared detection element arrays in each two-dimensional infrared detection element block are the lowest. The output signal of the infrared detection element that is selected once for scanning and is selected for operation in the first horizontal scanning selection period immediately after switching to the vertical scanning selection is, for example, an electric signal as a result of imaging the temperature distribution of the subject. Since it is not handled as a signal, a highly accurate infrared detector output signal can be obtained without being affected by the switching noise that occurs when vertical scanning is selected. , For example, it is possible to image the temperature distribution of the object at high speed.

  Further, since the differential amplifiers 61 to 6k, which are impedance conversion means, are connected between the outputs of the two-dimensional infrared detection element blocks 11 to 1k and the input of the block scanner 8, switching noise is generated when block scanning is selected. A high-accuracy infrared detection element output signal can be obtained without occurrence, and the temperature distribution of the subject can be imaged at high speed.

  In the above-described embodiment of the present invention, a thermopile is assumed as the infrared detection element. However, the infrared detection element is not limited to the thermopile, and may be a thermocouple, an infrared photovoltaic cell, or the like.

It is a circuit block diagram explaining the infrared rays detection apparatus which shows one Embodiment of this invention. It is a 1st time chart explaining the infrared rays detection apparatus by one Embodiment of this invention. It is a 2nd time chart explaining the infrared rays detection apparatus by one Embodiment of this invention.

Explanation of symbols

11 to 1k: two-dimensional infrared detection element block, 2: counter, 3: vertical decoder, 41-4k: horizontal decoder, 51-5k: horizontal scanner, 61-6k: differential amplifier, 7: block decoder 8: Block scanner, 91-9k: Delay circuit.

Claims (3)

When m, n, and k are integers of 2 or more, they are arranged in a matrix of m rows and n columns having m rows in the first direction and n columns in the second direction orthogonal to the first direction. An infrared detection unit comprising k two-dimensional infrared detection element blocks each having an infrared detection element arranged in a row in the second direction;
The output signals of the infrared detection elements arranged in the same row are scanned and selected from the output signals of the infrared detection elements arranged in the first row to the output signals of the infrared detection devices arranged in the mth row. First scanning means;
One-to-one correspondence with the k two-dimensional infrared detection element blocks, and the output signal of the infrared detection element selected by the first scanning means in the corresponding two-dimensional infrared detection element block is the first K second scanning means for scanning and selecting from the output signal of the infrared detection element in the column to the output signal of the infrared detection element in the nth column;
Block scanning means for selecting and outputting the output signal of the second scanning means from the output signal of the first second scanning means to the output signal of the kth second scanning means. ,
The time when the output signals of the infrared detection elements arranged in one row by the first scanning means are selected is T1, and the output signal of one of the infrared detection elements is selected by the second scanning means. T2 is longer than T2 and T2 is longer than T3. In
When i is an integer greater than or equal to 2 and less than or equal to k, the infrared ray by the first second scanning means is delayed by T3 from the time when the row selection by the first scanning means is switched to the selection of the next line. The scanning selection of the output signal of the detection element is started, and the i-th second scanning signal is delayed by T3 from the time when the scanning selection of the output signal of the infrared detection element is started by the (i-1) -th second scanning means. The infrared detection apparatus according to claim 1, wherein scanning selection of an output signal of the infrared detection element by the scanning means is started.   2. The infrared detection apparatus according to claim 1, wherein T1 is set to n + 1 times T2 or more, and the output of the second scanning unit immediately after the selection of the row by the first scanning unit is switched to the selection of the next row. An infrared detecting device characterized in that a signal is not handled as an electrical signal corresponding to the intensity of incident infrared rays.   3. The infrared detection apparatus according to claim 1, wherein the output of the second scanning unit is impedance-converted by an impedance conversion unit and input to the block scanning unit.

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