JP4816210B2 - Infrared detector - Google Patents

Description

  The present invention relates to an infrared detection apparatus that images a temperature distribution of a subject using a plurality of infrared detection elements that convert incident infrared light into an electrical signal.

  2. Description of the Related Art Conventionally, an infrared detection device that detects a temperature distribution of a subject in real time by arranging a plurality of infrared detection elements side by side is widely known. In such an infrared detection device, if any one of the detection elements becomes a defective element that does not operate normally due to an internal disconnection or the like, a correct output signal may not be obtained from the defective element. Therefore, a method disclosed in Patent Document 1 is known as a method for detecting a correct temperature distribution of a subject by complementing an output signal from such a defective element. In this method, by moving the mirror or prism to switch the incident angle to the two-dimensionally arranged infrared detecting elements, the light receiving operation is performed at two different incident angles, and the output signal values at both incident angles are stored in the memory. Remember it. When there is a defective element, the signal value output from the defective element at one incident angle is replaced with the signal value output from the normal element at the corresponding position at the other incident angle. Complement the output signal.

Japanese Patent Laid-Open No. 9-210798

  The method disclosed in Patent Document 1 is used in a normal infrared detection device such as a mirror or prism for switching the incident angle, a mechanism for moving the mirror or prism, and a memory for storing an output signal value. Requires no special hardware configuration. However, if a special hardware configuration for complementing the output signal from such a defective element is added to the infrared detection device, the device becomes large and expensive.

An infrared detection apparatus according to the present invention includes a plurality of infrared detection elements arranged on a semiconductor substrate, a scan selection unit that sequentially selects the plurality of infrared detection elements, an infrared detection element selected by the scan selection unit , or a scan selection. A signal output line that is connected to one of the infrared detection elements adjacent to the infrared detection element selected by the means and outputs a detection signal output from the connected infrared detection element according to the intensity of the incident infrared rays; and scanning The detection signal output from the infrared detection element selected by the selection means is compared with a predetermined threshold value. When the detection signal is equal to or greater than the threshold value, the first signal is output. When the first signal is output from the signal determination switch that outputs the second signal and the signal determination switch, the infrared detection element is connected to the signal output line, and the signal determination switch When the second signal is output from the switch, the infrared signal is output when the second signal is output from the first signal selection switch that cuts off the connection between the infrared detection element and the signal output line. When the infrared detection element adjacent to one side of the detection element is connected to the signal output line and the first signal is output from the signal determination switch, the infrared ray adjacent to either side of the infrared detection element When the second signal is output from the second signal selection switch that cuts off the connection between the detection element and the signal output line and the signal determination switch, the infrared detection element adjacent to the other side of the infrared detection element is When connected to the signal output line and the first signal is output from the signal determination switch, the connection between the infrared detection element adjacent to the other side of the infrared detection element and the signal output line is cut off. And when a second signal is output from the signal determination switch when any one of the infrared detection elements is selected by the scanning selection means, the detection signal output from the infrared detection element Instead, the detection signals output from the infrared detection elements adjacent to both sides of the infrared detection element and connected to the signal output line by the second signal selection switch and the third signal selection switch are averaged and output. By doing so, the detection signal from the said infrared detection element is complemented.
Another infrared detection apparatus according to the present invention includes a plurality of infrared detection elements arranged on a semiconductor substrate, scanning selection means for sequentially selecting the plurality of infrared detection elements, and infrared detection elements selected by the scanning selection means, or A signal output line connected to any one of the infrared detection elements adjacent to the infrared detection element selected by the scanning selection means, and outputting a detection signal output from the connected infrared detection element in accordance with the intensity of the incident infrared rays; The detection signal output from the infrared detection element selected by the scanning selection means is compared with a predetermined threshold value, and if it is equal to or greater than the threshold value, the first signal is output and is less than the threshold value. If the first signal is output from the signal determination switch that outputs the second signal and the signal determination switch, the infrared detection element is connected to the signal output line, When the second signal is output from the switch, the infrared signal is detected when the second signal is output from the first signal selection switch that cuts off the connection between the infrared detection element and the signal output line, and the signal determination switch. When an infrared detection element adjacent to one side of the element is connected to the signal output line and the first signal is output from the signal determination switch, infrared detection adjacent to either side of the infrared detection element A second signal selection switch that cuts off the connection between the element and the signal output line, and when the second signal is output from the signal determination switch when any one of the infrared detection elements is selected by the scanning selection means, Instead of the detection signal output from the infrared detection element, it is adjacent to one of the infrared detection elements and connected to the signal output line by the second signal selection switch. By outputting a detection signal outputted from the infrared detection element is complementary to the detection signal from the infrared detector.

  According to the present invention, an output signal from a defective element can be complemented without adding a special hardware configuration necessary for switching the incident angle of infrared light, storing an output signal value, or the like.

-First embodiment-
A first embodiment of the present invention will be described. FIG. 1 is a circuit configuration diagram of an infrared detection device according to the first embodiment. The infrared detection apparatus shown in FIG. 1 includes an infrared detection element unit 1, a counter 2, a vertical direction decoder 3, a horizontal direction decoder 4, and a horizontal direction scanner unit 5.

  In the infrared detection element section 1, m pixels in the vertical direction, that is, the column direction, and n pixels in the horizontal direction, that is, the row direction, are two-dimensionally arranged on the semiconductor substrate. In FIG. 1, a pixel located at the p-th in the vertical direction and the q-th in the horizontal direction is represented as a pixel pq (p = 1 to m, q = 1 to n). Each pixel is provided with thermopiles (thermocouples) T11a to Tmna that convert incident infrared rays into electric signals by outputting a voltage value corresponding to the intensity of incident infrared rays as a detection signal. The thermopiles T11a to Tmna can be expressed as an equivalent circuit in which a reference voltage Vref is applied in series with a resistor and a voltage source as shown in FIG. Such an infrared detection element is called a thermopile type two-dimensional infrared detection element.

  The thermopile type infrared detection element used in the infrared detection element unit 1 is placed in a hollow space by supporting a heat receiving unit that absorbs incident infrared light and converts it into heat via a beam, It has a structure in which a thermopile is wired in the beam. Such a structure is realized by micromachining. In the pixels 11 to mn having such a structure, incident infrared light is converted into an electrical signal by detecting a voltage generated in each thermopile due to a temperature difference between the heat receiving portion and the substrate portion. The magnitude of the voltage generated at this time varies depending on the intensity of the incident infrared light, but is at most about ± tens of μV in the thermopile type infrared detecting element.

  Since the pixels 11 to mn have the above-described structure, due to causes such as external impact applied during manufacture or vibration applied from the outside when mounted on a vehicle, The part of the beam supporting the heat receiving part may be broken. In this case, since the resistor constituting the thermopile is disconnected, the voltage value of the detection signal output from the pixel is almost 0 V, which is equal to the ground voltage. A pixel in which a normal detection signal cannot be obtained in this way is called a defective pixel. Note that defective pixels may be caused by causes other than the broken beam.

  The drain terminals of the switching transistors M11 to Mmn using N-type MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistors) are connected to the thermopiles T11a to Tmna provided in each pixel of the infrared detection element unit 1. . The source terminals of the switches M11 to Mmn are connected to the horizontal scanner 5 for each pixel column. Switching operations of the switches M11 to Mmn are controlled by vertical direction selection signals Y1 to Ym inputted from the vertical direction decoder 3 to the gate terminals. As a result, one of the pixel rows is selected in accordance with the vertical direction selection signals Y1 to Ym, and detection signals V1 to Vn by the respective thermopiles provided in the pixel row are output to the horizontal scanner 5.

  The counter 2 outputs an address count signal corresponding to the number of pixels of the infrared detection element unit 1 to the vertical direction decoder 3 and the horizontal direction decoder 4 based on the input clock signal (CLK). The vertical direction decoder 3 outputs vertical direction selection signals Y1 to Ym to each pixel of the infrared detection element unit 1 based on the address count signal output from the counter 2. On the other hand, the horizontal decoder 4 outputs horizontal selection signals X1 to Xn to the horizontal scanner unit 5 based on the address count signal output from the counter 2.

  The horizontal scanner unit 5 sequentially selects the detection signals V1 to Vn from the infrared detection element unit 1 on the basis of the horizontal direction selection signals X1 to Xn output from the horizontal decoder 4, and serves as a signal output line to the outside. Output voltage Vp is output. At this time, if there is a defective pixel as described above in the infrared detection element unit 1, a defective pixel is detected using the detection signals of normal pixels adjacent to the left and right of the defective pixel by a circuit operation described later. Complement the detection signal from the pixel. Thus, the correct output voltage Vp is obtained.

  A circuit configuration diagram of the horizontal scanner unit 5 is shown in FIG. The horizontal scanner unit 5 is provided with various switches corresponding to the respective pixel columns of the infrared detection element unit 1. The various switches include signal determination switches M1a to Mna, signal selection switches M1b to Mnb, M1c to Mnc and M2e to M (n-1) e, and scanning selection switches M1d to Mnd and M2f. ~ M (n-1) f is included. The signal selection switches M2e to M (n-1) e and the scan selection switches M2f to M (n-1) f are provided when adjacent pixel columns exist on both sides of the corresponding pixel column. . That is, they are not provided at both ends corresponding to the pixel columns of the pixels 11 to m1 and the pixel columns of the pixels 1n to mn. The signal selection switch M (n-1) e and the scan selection switch M (n-1) f are not shown in FIG. P-type MOSFETs are used for the signal selection switches M1b to Mnb, and N-type MOSFETs are used for all other switches.

  The signal determination switches M1a to Mna are grounded by connecting the source terminal to the ground. The power supply voltage Vcc is input to the drain terminal via the resistors R1 to Rn, and the detection signals V1 to Vn from the infrared detection element unit 1 are input to the gate terminal, respectively. When the threshold voltage of the signal determination switches M1a to Mna is Vth, the threshold voltage Vth is set to be a predetermined voltage between the reference voltage Vref and the ground voltage, for example, Vref / 2.

  As described above, the fluctuation range of the detection signals V1 to Vn is about ± several μV at most in the thermopile type infrared detection element. Therefore, by setting the threshold voltage Vth as described above, the signal determination switches M1a to Mna. Whether or not the detection signals V1 to Vn are normal can be determined by the above operation. That is, if the detection signals V1 to Vn are normal, the voltage thereof becomes higher than the threshold voltage Vth, so that the signal determination switches M1a to Mna are turned on. On the other hand, when the detection signals V1 to Vn are not normal due to the output of the detection signal from the defective pixel, the voltage becomes equal to the ground voltage and thus becomes lower than the threshold voltage Vth, and the signal determination switches M1a to Mna. Is turned off.

  The signal selection switches M1b to Mnb, M1c to Mnc, and M2e to M (n-1) e are all connected to the drain terminals of the signal determination switches M1a to Mna corresponding to the same pixel column. For example, the gate terminals of the signal selection switches M1b and M1c corresponding to the pixel columns of the pixels 11 to m1 are connected to the drain terminals of the signal determination switches M1a corresponding to the pixel columns of the pixels 11 to m1. The gate terminals of the signal selection switches M2b, M2c, and M2e corresponding to the pixel columns of the pixels 12 to m2 are connected to the drain terminal of the signal determination switch M2a corresponding to the same pixel column. The on / off state of each signal selection switch is switched by the operation of the signal determination switch to which this gate terminal is connected.

  Of the detection signals V1 to Vn, those output from the pixel column corresponding to the signal selection switch are input to the source terminals of the signal selection switches M1b to Mnb, respectively. For example, the detection signal V1 is input to the source terminal of the signal selection switch M1b corresponding to the pixel column of the pixels 11 to m1. The detection signal V2 is input to the source terminal of the signal selection switch M2b corresponding to the pixel column of the pixels 12 to m2.

  The drain terminals of the signal selection switches M1c to Mnc and M2e to M (n-1) e are any of the detection signals V1 to Vn output from the pixel column adjacent to the pixel column to which the signal selection switch corresponds. Either one is entered. For example, the detection signal V2 from the pixel column of the pixels 12 to m2 adjacent to the right side of the pixel column is input to the drain terminal of the signal selection switch M1c corresponding to the pixel column of the pixels 11 to m1. In addition, the drain terminals of the signal selection switches M2c and M2e corresponding to the pixel columns of the pixels 12 to m2 include the detection signal V1 from the pixel column of the pixels 11 to m1 adjacent to the left side of the pixel column and the right side. Detection signals V3 are input from the pixel columns of the adjacent pixels 13 to m3.

  The drain terminals of the signal selection switches M1b to Mnb and the source terminals of M1c to Mnc are all connected to one of the drain terminals of the scan selection switches M1d to Mnd corresponding to the same pixel column. The source terminals of the signal selection switches M2e to M (n-1) e are respectively connected to the drain terminals of the scan selection switches M2f to M (n-1) f corresponding to the same pixel column.

  As described above, the on / off state of each signal selection switch is switched by the operation of the signal determination switch connected to the gate terminal of each signal selection switch. Accordingly, any one of the detection signals V1 to Vn input to each signal selection switch is appropriately selected and output to the scan selection switch.

  The corresponding ones of the horizontal direction selection signals X1 to Xn are input to the gate terminals of the scan selection switches M1d to Mnd and M2f to M (n-1) f, respectively. For example, the horizontal direction selection signal X1 is input to the gate terminal of the scanning selection switch M1d, and the horizontal direction selection signal X2 is input to the gate terminals of the scanning selection switches M2d and M2f. The on / off state of each scanning selection switch is switched by a horizontal direction selection signal input to the gate terminal.

  The drain terminals of the scan selection switches M1d to Mnd are respectively connected to the drain terminals of the signal selection switches M1b to Mnb and the source terminals of M1c to Mnc corresponding to the same pixel column. The drain terminals of the scan selection switches M2f to M (n-1) f are connected to the source terminals of the signal selection switches M2e to M (n-1) e corresponding to the same pixel column, respectively. The source terminals of the scan selection switches M1d to Mnd and M2f to M (n-1) f are all connected to an external signal output line. That is, the source terminal voltages of the scan selection switches M1d to Mnd and M2f to M (n−1) f are output to the outside as the output voltage Vp.

  As described above, the on / off states of the scan selection switches are switched by the horizontal direction selection signals X1 to Xn input to the gate terminals of the scan selection switches. As a result, as described above, one of the detection signals V1 to Vn input to the drain terminal of each scan selection switch is selected and output to the output voltage Vp.

  Next, the operation of the infrared detection device described above will be described together with the specific circuit operation of the horizontal scanner unit 5. FIG. 3 shows a time chart of signals output in the infrared detection apparatus of the present embodiment. The counter 2 counts the number of pixels corresponding to the number of pixels of the infrared detection element unit 1, that is, m × n, based on the input reference clock CLK, and outputs it to the vertical direction decoder 3 and the horizontal direction decoder 4 as address count signals. To do.

  The vertical direction decoder 3 decodes the address count signal from the counter 2 and outputs vertical direction selection signals Y1 to Ym as indicated by reference numeral 11 in FIG. 3 to the switches M11 to Mmn in the pixels 11 to mn. To do. The horizontal decoder 4 decodes the address count signal from the counter 2 and outputs horizontal direction selection signals X1 to Xn as indicated by reference numeral 12 in FIG.

  The vertical direction selection signals Y1 to Ym are sequentially set to the H (high) level at the timing indicated by reference numeral 11. First, the vertical direction selection signal Y1 becomes H level. As a result, the switches M11 to M1n in the pixel rows of the pixels 11 to 1n are turned on so that the drain and the source are conductive, and the voltage value according to the intensity of the incident infrared ray detected in the pixel row becomes the detection signal. Output to V1 to Vn. As a result, while the vertical direction selection signal Y1 is at the H level, detection signals V1 to Vn as indicated by reference numeral 14 in FIG. At this time, the pixels 11 to 1n are all normal, and the values of the detection signals V1 to Vn are in a normal range. As indicated by reference numeral 13, the reference voltage Vref is always constant.

  As shown in the circuit configuration diagram of FIG. 2, the detection signals V1 to Vn output to the horizontal scanner unit 5 include gate terminals of signal determination switches M1a to Mna, source terminals of signal selection switches M1b to Mnb, The signal selection switches M1c to Mnc and M2e to M (n-1) e are input to the drain terminals, respectively. Here, since the values of the detection signals V1 to Vn are all in a normal range, the gate terminal voltages of the signal determination switches M1a to Mna are higher than the threshold voltage Vth. As a result, the signal determination switches M1a to Mna are turned on to conduct between the drain and the source, and the drain terminal is connected to the ground. Thereby, the drain terminal voltages of the signal determination switches M1a to Mna become L (low) level substantially equal to the ground voltage.

  When the drain terminal voltages of the signal determination switches M1a to Mna become L level, the gate terminal voltages of the signal selection switches M1b to Mnb, M1c to Mnc, and M2e to M (n-1) e connected to the drain terminals are also L. Become a level. Then, the signal selection switches M1b to Mnb that are P-type MOSFETs are turned on, and the other signal selection switches are turned off. As a result, the source and drain of the signal selection switches M1b to Mnb are conducted, and the detection signals V1 to Vn input to the source terminal are output to the drain terminal side.

  As described above, the drain terminals of the scan selection switches M1d to Mnd are connected to the drain terminal sides of the signal selection switches M1b to Mnb, respectively. Therefore, the detection signals V1 to Vn are input to the drain terminals of the scan selection switches M1d to Mnd as a result of the conduction between the source and drain of the signal selection switches M1b to Mnb as described above.

  Horizontal direction selection signals X1 to Xn output from the horizontal direction decoder 3 are input to gate terminals of the scan selection switches M1d to Mnd. The horizontal direction selection signals X1 to Xn sequentially become H level at the timing indicated by reference numeral 12 in FIG. 3 while the vertical direction selection signal Y1 is at H level. Then, the scan selection switches M1d to Mnd are sequentially turned on and the drain and source are made conductive, so that the pixels 11 to 1n are sequentially connected to the signal output lines via the signal selection switches M1b to Mnb. As a result, the detection signals V1 to Vn are sequentially output as the output voltage Vp.

  That is, when the horizontal direction selection signal X1 is at the H level, the scanning selection switch M1d is turned on, whereby the pixel 11 is connected to the signal output line, and the detection signal V1 is output as the output voltage Vp. Next, when the horizontal direction selection signal X2 is at the H level, the scanning selection switch M2d is turned on to connect the pixel 12 to the signal output line, and the detection signal V2 is output as the output voltage Vp.

  The scan selection switches M2f to M (n-1) f are sequentially turned on in response to the horizontal direction selection signals X1 to Xn, but the signal selection switches M2e to M (n-1) connected to these drain terminals. ) E is off as described above. That is, the connection between the pixels 11 to 1n and the signal output line is cut off at the signal selection switches M2e to M (n-1) e. Therefore, no detection signal is output from the scan selection switches M2f to M (n-1) f.

  When there is no defective pixel, the circuit operation as described above is performed in the horizontal scanner unit 5. As a result, while the vertical direction selection signal Y1 is at the H level, an output voltage Vp having a waveform as indicated by reference numeral 15 in FIG. 3 is obtained. In this way, normal pixels 11 to 1n are sequentially scanned and selected, and their detection signals V1 to Vn are output as they are to the output voltage Vp.

  If the pixels 11 to 1n are sequentially selected as described above, then the vertical direction selection signal Y1 becomes L level and the vertical direction selection signal Y2 becomes H level. As a result, the switches M21 to M2n in the pixel rows of the pixels 21 to 2n are turned on so that the drain-source is electrically connected, and the voltage value corresponding to the intensity of the incident infrared rays detected in the pixel row becomes the detection signal. Output to V1 to Vn. As a result, while the vertical direction selection signal Y2 is at the H level, detection signals V1 to Vn as indicated by reference numeral 14 in FIG. At this time, it is assumed that the pixel 22 among the pixels 21 to 2n is a defective pixel caused by the above-described cause, and the value of the detection signal V2 output from the defective pixel 22 is approximately 0V.

  Since the values other than V2 in the detection signals V1 to Vn are in the normal range, the gate terminal voltages of the signal determination switches M1a to Mna excluding M2a are higher than the threshold voltage Vth. As a result, the signal determination switches M1a to Mna other than M2a are turned on to conduct between the drain and the source, and the drain terminal voltage becomes L level. When the signal determination switches M1a to Mna except M2a are turned on in this way, the detection signals V1 to Vn other than V2 are connected to the drain terminals of the scan selection switches M1d to Mnd except M2d by the circuit operation as described above. Entered.

  On the other hand, since the value of the detection signal V2 is approximately 0 V, the gate terminal voltage of the signal determination switch M2a is lower than the threshold voltage Vth. As a result, the signal determination switch M2a is turned off, and the drain terminal voltage becomes H level substantially equal to the power supply voltage Vcc. Therefore, the gate terminal voltages of the signal selection switches M2b, M2c, and M2e connected to the drain terminal of the signal determination switch M2a are also at the H level. Then, the signal selection switch M2b of the P-type MOSFET is turned off, and the signal selection switches M2c and M2e of the N-type MOSFET are turned on. As a result, the drains and the sources of the signal selection switches M2c and M2e become conductive, and the detection signals V1 and V3 input to the drain terminals are output to the source terminals, respectively.

  As described above, the drain terminals of the scan selection switches M2d and M2f are connected to the source terminal sides of the signal selection switches M2c and M2e, respectively. Therefore, the detection signals V1 and V3 are input to the drain terminals of the scan selection switches M2d and M2f, respectively, by conducting between the drain and source of the signal selection switches M2c and M2e as described above.

  Other than X2 among the horizontal direction selection signals X1 to Xn output from the horizontal direction decoder 3 are input to the gate terminals of the scan selection switches M1d to Mnd except M2d. The horizontal direction selection signals X1 to Xn sequentially become H level at the timing indicated by reference numeral 12 in FIG. 3 while the vertical direction selection signal Y2 is at H level. Accordingly, the scan selection switches M1d to Mnd except M2d are sequentially turned on, and the pixels 21 to 2n except the defective pixel 22 are sequentially connected to the signal output lines via the signal selection switches M1b to Mnb. As a result, detection signals V1 to Vn other than V2 are sequentially output as the output voltage Vp.

  That is, when the horizontal direction selection signal X1 is at the H level, the scanning selection switch M1d is turned on, whereby the pixel 21 is connected to the signal output line via the signal selection switch M1b, and the detection signal V1 is output from the output voltage Vp. Is output as When the horizontal direction selection signal X3 is at the H level, the scanning selection switch M3d is turned on, so that the pixel 23 is connected to the signal output line via the signal selection switch M3b, and the detection signal V3 is output to the output voltage Vp. Is output as

  On the other hand, the horizontal direction selection signal X2 is input to the gate terminals of the scan selection switches M2d and M2f. When the horizontal direction selection signal X2 becomes H level while the vertical direction selection signal Y2 is H level, the scanning selection switches M2d and M2f are turned on. In this case, the pixel 21 and the pixel 23 are connected to the signal output line via the signal selection switches M2c and M2e, respectively. As a result, the average value of the detection signals V1 and V3 is output as the output voltage Vp. At this time, the connection between the defective pixel 22 and the signal output line is cut off because the signal selection switch M2b is off. Therefore, the detection signal V2 from the defective pixel 22 is not output.

  When there is a defective pixel, the circuit operation as described above is performed in the horizontal scanner unit 5. As a result, while the vertical direction selection signal Y2 is at the H level, an output voltage Vp having a waveform as indicated by reference numeral 15 in FIG. 3 is obtained. At this output voltage Vp, when the defective pixel 22 is selected for scanning, the detection signal V2 from the defective pixel is complemented by the average of the detection signals V1 and V3 output from the normal pixel 21 and the pixel 23 adjacent to the left and right, respectively. Has been. In this way, the pixels 21 to 2n including the defective pixel 22 are sequentially scanned and selected, and the detection signals V1 to Vn excluding the detection signal V2 from the defective pixel 22 and a signal complementing the detection signal V2 are output voltages. Is output to Vp.

  As described above, according to the infrared detection device of this embodiment, it is possible to detect from the defective element without adding a special hardware configuration necessary for switching the incident angle of infrared light or storing the detection signal. The output signal can be complemented.

  In addition, in a thermopile type infrared detection element having a high output impedance such as the infrared detection element unit 1, if the detection signal from the defective pixel is output as it is without being complemented, the output impedance is high, so that it is connected to the subsequent stage. Depending on the input capacitance of the circuit, the time constant may be long. In this case, when the scan selection is switched from the defective pixel to the next pixel, it takes a long time for the output voltage to change due to the influence of the long time constant, and therefore the scan selection cycle cannot be shortened. The problem arises. However, such a problem can be solved by complementing the detection signal from the defective pixel as described above.

According to the first embodiment described above, the following operational effects can be achieved.
(1) Switches M11 to Mmn, scan selection switches M1d to Mnd, and M2f based on vertical direction selection signals Y1 to Ym output from the vertical direction decoder 3 and horizontal direction selection signals X1 to Xn output from the horizontal direction decoder 4 The pixels 11 to mn are sequentially selected by controlling .about.M (n-1) f, and detection signals of the thermopiles T11a to Tmna provided in the respective pixels are output. At this time, a defective element for which a normal output signal cannot be obtained is detected from each pixel, and when a defective element is detected, an output signal of a non-defective element adjacent to the defective element is used as an output signal of the defective element. I decided to output it. Since it did in this way, the output signal from a defective element can be complemented, without adding the special hardware structure required for the change of the incident angle of infrared light, the memory | storage of a detection signal, etc.

  Specifically, the signal determination switches M1a to Mna compare the detection signal output from the thermopile of the selected pixel with a predetermined threshold value Vth. If it is less than the threshold value, an H level signal is output. Thereby, it is determined whether or not the detection signal is within a predetermined range. As a result, when it is determined that the detection signal is within a predetermined range and an L level signal is output, the signal selection switches M1b to Mnb are turned on to connect the pixel to the signal output line and the signal selection is performed. The switches M1c to Mnc and M2e to M (n-1) e are turned off to cut off the connection between the pixel adjacent to the pixel and the signal output line. Thereby, when there is no defective pixel, the detection signals V1 to Vn are output as they are to the output voltage Vp.

  When it is determined that the detection signal is outside the predetermined range and an H level signal is output, the signal selection switches M1b to Mnb are turned off to disconnect the connection between the pixel and the signal output line, and The selection switches M1c to Mnc and M2e to M (n-1) e are turned on to connect the pixels adjacent to the pixel to the signal output line. Thereby, if there is a defective pixel, the detection signal from the defective pixel is complemented, and the detection signals V1 to Vn excluding the detection signal from the defective pixel and the complemented detection signal are output to the output voltage Vp.

(2) When a defective element is detected, an output signal of a non-defective element adjacent to both sides of the defective element is output as an output signal of the defective element. Specifically, when it is determined that the detection signal is outside the predetermined range and an H level signal is output, by turning on the signal selection switches M1c to Mnc and M2e to M (n−1) e, Pixels adjacent to both sides of the pixel are connected to the signal output line. Thereby, instead of the detection signal output from the infrared detection element, the detection signal output from the infrared detection element adjacent to both sides of the infrared detection element is averaged and output, thereby allowing the detection from the infrared detection element. The detection signal was complemented. Since it did in this way, the output signal from a defective element can be complemented reliably.

(3) The signal determination switches M1a to Mna and the signal selection switches M1b to Mnb, M1c to Mnc, and M2e to M (n-1) e are respectively provided for the columns of the pixels 11 to mn arranged in a two-dimensional manner. It was decided to be provided. Since it did in this way, the number of signal determination switches and signal selection switches can be minimized.

-Second Embodiment-
Next, a second embodiment of the present invention will be described. In the infrared detection apparatus according to the second embodiment, a horizontal scanner 5A having a different circuit configuration is used instead of the horizontal scanner 5 having the circuit configuration shown in FIG. If there is a defective pixel, the horizontal scanner 5A supplements the detection signal of the defective pixel using the detection signal of the normal pixel adjacent to either the left or right of the defective pixel. The other points are the same as in the first embodiment.

  FIG. 4 shows a circuit configuration diagram of the horizontal scanner unit 5A. The horizontal scanner unit 5A includes signal determination switches M1a to Mna, signal selection switches M1b to Mnb and M1c to Mnc, and scanning selection switches M1d to Mnd. These various switches operate in the same manner as the various switches of the horizontal scanner unit 5 according to the first embodiment shown in FIG.

  That is, the signal determination switches M1a to Mna are turned on when the detection signals V1 to Vn are normal, and are turned off when they are not normal. In accordance with this switching operation, the on / off states of the signal selection switches M1b to Mnb and M1c to Mnc are switched. When the signal determination switches M1a to Mna are on, the signal selection switches M1b to Mnb are on and the signal selection switches M1c to Mnc are off. Conversely, when the signal determination switches M1a to Mna are off, the signal selection switches M1c to Mnc are on and the signal selection switches M1b to Mnb are off. Then, the on / off states of the scan selection switches M1d to Mnd are switched according to the horizontal direction selection signals X1 to Xn output from the horizontal direction decoder 4. When any of the horizontal direction selection signals X1 to Xn is at the H level, any of the corresponding scan selection switches M1d to Mnd is turned on, and the others are turned off.

  FIG. 5 shows a time chart of signals output in the infrared detection apparatus of the present embodiment. Similarly to the first embodiment, the vertical direction decoder 3 decodes the address count signal from the counter 2 and outputs the vertical direction selection signals Y1 to Ym as indicated by reference numeral 21 in FIG. 5 in the pixels 11 to mn. Are output to the switches M11 to Mmn. The horizontal direction decoder 4 decodes the address count signal from the counter 2 and outputs horizontal direction selection signals X1 to Xn as indicated by reference numeral 22 in FIG. 5 to the horizontal direction scanner unit 5A.

  First, when the vertical direction selection signal Y1 becomes H level, the switches M11 to M1n in the pixel rows of the pixels 11 to 1n are turned on, and a voltage value corresponding to the intensity of incident infrared rays detected in the pixel row. Are output to the detection signals V1 to Vn. As a result, while the vertical direction selection signal Y1 is at the H level, detection signals V1 to Vn as indicated by reference numeral 24 in FIG. 5 are output to the horizontal direction scanner unit 5A. At this time, the pixels 11 to 1n are all normal, and the values of the detection signals V1 to Vn are in a normal range. As indicated by reference numeral 23, the reference voltage Vref is always constant.

  In this case, the horizontal scanner unit 5A outputs the detection signals V1 to Vn from the scan-selected pixel rows as they are to the output voltage Vp by the same circuit operation as that of the horizontal scanner unit 5 according to the first embodiment. That is, when the detection signals V1 to Vn are output from the normal pixels 11 to 1n, the signal selection switches M1b to Mnb that are P-type MOSFETs are turned on, and conversely, the signal selection switches M1c to Mnc using N-type MOSFETs. Is turned off. Then, the detection signals V1 to Vn are input to the drain terminals of the scan selection switches M1d to Mnd. When the horizontal direction selection signals X1 to Xn sequentially become H level at the timing indicated by reference numeral 22 in FIG. 5 while the vertical direction selection signal Y1 is at H level, the scan selection switches M1d to Mnd are sequentially turned on. Thus, the pixels 11 to 1n are sequentially connected to the signal output lines via the signal selection switches M1b to Mnb. As a result, the detection signals V1 to Vn are sequentially output as the output voltage Vp.

  As a result, while the vertical direction selection signal Y1 is at the H level, an output voltage Vp having a waveform as indicated by reference numeral 25 in FIG. 5 is obtained. When there is no defective pixel, the normal pixels 11 to 1n are sequentially selected in this way, and the detection signals V1 to Vn are output as they are to the output voltage Vp.

  If the pixels 11 to 1n are sequentially selected as described above, then the vertical direction selection signal Y1 becomes L level and the vertical direction selection signal Y2 becomes H level. Thereby, the switches M21 to M2n in the pixel rows of the pixels 21 to 2n are turned on, and voltage values corresponding to the intensity of the incident infrared rays detected in the pixel rows are output to the detection signals V1 to Vn. As a result, while the vertical direction selection signal Y2 is at the H level, detection signals V1 to Vn as indicated by reference numeral 24 in FIG. 5 are output to the horizontal direction scanner unit 5A. At this time, the pixel 22 among the pixels 21 to 2n is a defective pixel, and the value of the detection signal V2 output from the defective pixel 22 is approximately 0V.

  In this case, when the detection signals V1 to Vn are output from the pixels 21 to 2n including the defective pixel 22, the signal selection switch M2b corresponding to the defective pixel 22 is selected from the signal selection switches M1b to Mnb that are P-type MOSFETs. Excluded is turned on. Thus, the detection signals V1 to Vn excluding V2 are respectively input to the drain terminals of the scan selection switches M1d to Mnd except for the scan selection switch M2d connected to the signal selection switch M2b. In addition, among the signal selection switches M1c to Mnc that are N-type MOSFETs, the signal selection switch M2c corresponding to the defective pixel 22 is turned on. As a result, the detection signal V1 from the normal pixel 21 adjacent to the left side of the defective pixel 22 is input to the drain terminal of the scan selection switch M2d connected to the signal selection switch M2c.

  In such a state, while the vertical direction selection signal Y2 is at the H level, the horizontal direction selection signals X1 to Xn are sequentially at the H level at the timing indicated by reference numeral 22 in FIG. M1d to Mnd are sequentially turned on. Accordingly, the pixels 21 to 2n excluding the defective pixel 22 are sequentially connected to the signal output line via the signal selection switches M1b to Mnb, and the pixel 21 is connected to the signal output line via the signal selection switch M2c. . At this time, the connection between the defective pixel 22 and the signal output line is cut off because the signal selection switch M2b is off. Therefore, the detection signal V2 from the defective pixel 22 is not output. As a result, the detection signals V1 to Vn excluding V2 input to the drain terminals of the scan selection switches M1d to Mnd excluding M2d and the detection signal V1 input to the drain terminal of the scan selection switch M2d are sequentially output as the output voltage Vp. Is output.

  By the circuit operation as described above, the output voltage Vp having a waveform as shown by reference numeral 25 in FIG. 5 is obtained while the vertical direction selection signal Y2 is at the H level. In this output voltage Vp, when the defective pixel 22 is selected for scanning, the detection signal V2 from the defective pixel is complemented by the detection signal V1 output from the normal pixel 21 adjacent to the left side. When there is a defective pixel, the pixels 21 to 2n including the defective pixel 22 are sequentially selected in this manner, and the detection signals V1 to Vn excluding the detection signal V2 from the defective pixel 22 and the detection signal V2 are obtained. The complemented signal is output to the output voltage Vp.

  According to the second embodiment described above, when a defective element is detected, an output signal of a non-defective element adjacent to one of the defective elements is output as an output signal of the defective element. Specifically, when the signal determination switches M1a to Mna determine that the detection signal is outside a predetermined range and an H level signal is output, the signal selection switches M1c to Mnc are turned on to turn on the corresponding pixel. A pixel adjacent on either side is connected to a signal output line. Thereby, instead of the detection signal output from the infrared detection element, by outputting the detection signal output from the infrared detection element adjacent to one of the infrared detection elements, the infrared detection element It was decided to complement the detection signal. Since it did in this way, the output signal from a defective element can be supplemented with a simple circuit configuration.

  In each of the embodiments described above, an example in which various switches are provided in the horizontal scanner unit 5 or 5A corresponding to each pixel column of the pixels 11 to mn arranged in a two-dimensional manner. Explained. However, by switching the vertical and horizontal sides of the infrared detection element unit 1, various switches similar to those in the horizontal scanner unit 5 or 5A corresponding to the pixel rows of the pixels 11 to mn arranged two-dimensionally, respectively. It is good also as providing. Even if it does in this way, the effect similar to having mentioned above can be acquired.

  Further, in each of the embodiments described above, an example in which a thermopile is used as an infrared detection element that converts incident infrared light into an electrical signal has been described. However, the present invention is not limited to this content. Such a thing may be used. Moreover, although the example in which the infrared detection elements are arranged in a two-dimensional manner has been described, a one-dimensional arrangement may be used. In this case, for example, in the first embodiment, the infrared detection element unit 1 of FIG. 1 is configured by one row of pixels 11 to 1n, and further functions of the vertical decoder 3 and the vertical scanner in the infrared detection element unit 1. The switches M11 to M1n that perform the above are omitted. Other than this, the configuration is the same as that of the infrared detection device of FIG. Therefore, the same effect as the above-described effect can be obtained. The same applies to the second embodiment.

  In each of the embodiments described above, the configuration using the MOSFET for the amplification transistor and the switch has been described. However, the same configuration can be realized even if a bipolar transistor is used.

  In each of the embodiments described above, the infrared detecting element is realized by the thermopiles T11a to Tmna, and the scanning selection means is constituted by the counter 2, the vertical direction decoder 3, the horizontal direction decoder 4, the switches M11 to Mmn, and the scanning selection switches M1 to Mn. It was decided to realize. The detection means is realized by signal determination switches M1a to Mna, and the switching means is realized by signal selection switches M1b to Mnb, M1c to Mnc, or M2e to M (n-1) e. However, the above description is merely an example, and when interpreting the invention, there is no limitation or restriction on the correspondence between the items described in the above embodiment and the items described in the claims.

  Each embodiment and various modifications described above are merely examples, and the present invention is not limited to these contents as long as the features of the invention are not impaired.

It is a circuit block diagram of the infrared rays detection apparatus by the 1st Embodiment of this invention. It is a circuit block diagram of the horizontal direction scanner part by 1st Embodiment. It is a time chart of the signal output in the infrared rays detection apparatus by 1st Embodiment. It is a circuit block diagram of the horizontal direction scanner part by 2nd Embodiment. It is a time chart of the signal output in the infrared rays detection apparatus by 2nd Embodiment.

Explanation of symbols

1: Infrared detection element unit 2: Counter 3: Vertical direction decoder 4: Horizontal direction decoder 5, 5A: Horizontal direction scanner unit

Claims (2)

  A plurality of infrared detection elements arranged on a semiconductor substrate;
  Scanning selection means for sequentially selecting the plurality of infrared detection elements;
  The infrared detection element selected by the scan selection means or the infrared detection element adjacent to the infrared detection element selected by the scan selection means is connected, and the connected infrared detection element responds to the incident infrared intensity. A signal output line for outputting the output detection signal to the outside;
  The detection signal output from the infrared detection element selected by the scanning selection means is compared with a predetermined threshold value, and if it is equal to or greater than the threshold value, the first signal is output and is less than the threshold value. A signal determination switch for outputting a second signal in the case;
  When the first signal is output from the signal determination switch, the infrared detection element is connected to the signal output line, and when the second signal is output from the signal determination switch, the infrared detection element and the signal A first signal selection switch for cutting off the connection of the output line;
  When the second signal is output from the signal determination switch, an infrared detection element adjacent to one of the infrared detection elements is connected to the signal output line, and the first signal is output from the signal determination switch. A second signal selection switch that disconnects the signal output line from the infrared detection element adjacent to one of the infrared detection elements when output.
  When the second signal is output from the signal determination switch, the infrared detection element adjacent to the other side of the infrared detection element is connected to the signal output line, and the first signal is output from the signal determination switch. A third signal selection switch that disconnects the signal output line and the infrared detection element adjacent to the other side of the infrared detection element when output.
  When a second signal is output from the signal determination switch when any one of the infrared detection elements is selected by the scanning selection unit, the infrared detection element is used instead of the detection signal output from the infrared detection element. The detection signals output from the infrared detection elements connected to the signal output lines by the second signal selection switch and the third signal selection switch, respectively, are averaged and output. An infrared detection apparatus, wherein a detection signal from a detection element is complemented.   A plurality of infrared detection elements arranged on a semiconductor substrate;
  Scanning selection means for sequentially selecting the plurality of infrared detection elements;
  The infrared detection element selected by the scan selection means or the infrared detection element adjacent to the infrared detection element selected by the scan selection means is connected, and the connected infrared detection element responds to the incident infrared intensity. A signal output line for outputting the output detection signal to the outside;
  The detection signal output from the infrared detection element selected by the scanning selection means is compared with a predetermined threshold value, and if it is equal to or greater than the threshold value, the first signal is output and is less than the threshold value. A signal determination switch for outputting a second signal in the case;
  When the first signal is output from the signal determination switch, the infrared detection element is connected to the signal output line, and when the second signal is output from the signal determination switch, the infrared detection element and the signal A first signal selection switch for cutting off the connection of the output line;
  When the second signal is output from the signal determination switch, an infrared detection element adjacent to one of the infrared detection elements is connected to the signal output line, and the first signal is output from the signal determination switch. A second signal selection switch for cutting off the connection between the infrared detection element adjacent to either one of the infrared detection elements and the signal output line when output;
  When a second signal is output from the signal determination switch when any one of the infrared detection elements is selected by the scanning selection unit, the infrared detection element is used instead of the detection signal output from the infrared detection element. The detection signal output from the infrared detection element connected to the signal output line by the second signal selection switch is adjacent to either side of the detection signal. Infrared detector characterized by complementing.

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