JP2005274296A - Indication signal processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To resolve a problem that noise is mixed and gives a large error to measured results in the case that very small electromotive force of thermopile is amplified with an amplifier. <P>SOLUTION: The processor has a light receiver provided with a plurality of reception units arranged in the line writing direction and the column direction. It calculates a median from the first detection signal detected with the first unit among a plurality of light reception units and a plurality of detection signal detected with a plurality of light reception units adjacent to the first unit, replaces the median with the first detection signal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a display signal processing device that detects a heat ray image using heat radiated from an object, for example, far infrared rays, and detects the presence of a fire, a person, and the like, and the temperature of the object.

  A thermocouple is a device that generates a direct-current voltage by using the Seebeck effect that converts incident far infrared rays into heat and directly converts heat into electricity even in the case of far infrared rays emitted from a minute human body.

  The Seebeck effect is a characteristic that generates thermoelectromotive force when both ends of dissimilar metal wires are connected and a temperature difference between the contact points is given. A thermopile is one in which a large number of thermocouples are connected to increase the output voltage.

  A two-dimensional thermopile array is a combination of the above-described thermopile that can measure the amount of change in heat in a certain area by vertically and horizontally.

  Conventionally, a two-dimensional thermopile array is installed on a ceiling surface of a microwave oven or the like, and is used as a device that measures the temperature of an object to be measured without touching it directly.

  Specifically, the microwave oven can measure the temperature distribution of an object to be measured placed on the turntable using the turntable as a measurement area of a two-dimensional thermopile array. The above technique is described in Reference 1.

  Further, the above-described two-dimensional thermopile array technology has been adopted as a human body detection technique, and an illumination lamp incorporating a two-dimensional thermopile array has been proposed.

The thermopile can detect the presence of a fire or a person based on the amount of change in heat, and is useful as a display signal processing device. In recent years, thermopile is also highly expected as a fire alarm and a human body detection security device. The technique of human body detection is described in Reference Document 2.
JP 2001-355853 A JP 2000-223282 A

  In the thermopile, a number of thin film thermocouples made of polysilicon having a pair of P-type and N-type are connected in series on a silicon substrate. The thermopile has a structure in which the heat capacity of the hot junction portion is extremely reduced by forming a hollow portion directly below the center of the substrate.

  The thermopile operating principle uses the thermocouple electromotive force as the temperature change of the welded portion generated by receiving infrared rays. The generated electromotive force is very small and needs to be amplified several thousand times by a later-stage amplifier (amplifier).

  The electromotive force generated in the thermopile may be mixed with noise from the system clock for reading the thermopile. When noise is included in the electromotive force of a minute thermocouple, the amplification factor is large and a large error is given to the measurement result. As a result, there has been a problem that a measuring device that operates based on the measurement result of the electromotive force of a minute thermocouple is adversely affected and malfunctions.

  A main invention according to the present invention includes a light receiving unit including a plurality of light receiving units arranged in a row direction and a column direction, and a first detection signal detected from a first unit in the plurality of light receiving units; A median value is obtained from a plurality of detection signals detected from a plurality of light receiving units adjacent to the first unit, and the median value is replaced with a detection signal of the first unit.

  Further, other features of the present invention will become apparent from the accompanying drawings and the description of the present specification.

  According to the present invention, there is provided a light receiving unit including a plurality of light receiving units arranged in a row direction and a column direction, the first detection signal detected from a first unit in the plurality of light receiving units, and the first By obtaining a median value from a plurality of detection signals detected from a plurality of light receiving units adjacent to one unit, and replacing the median value with the detection signal of the first unit, each unit that differs greatly from the surrounding values An advantage is that the measured noise can be removed.

  Moreover, by using it for a heat ray detector, there is an advantage that a highly accurate fire alarm or a human body detection security device can be created.

  Details of the present invention will be specifically described with reference to the drawings. FIG. 1 is a block diagram showing a display signal processing apparatus of the present invention. In the display signal processing apparatus shown in FIG. 1, a thermopile far infrared area sensor 1 has a two-dimensional thermopile array 2, a scan circuit 3, and a temperature sensor device 4 inside.

The detected area 5 indicates a target area where the temperature is measured.
The detected area 5 is reduced and taken into the thermopile far infrared area sensor 1 through the lens 6. The two-dimensional thermopile array 2 obtains a weak electromotive force proportional to the amount of far-infrared rays for each area obtained by dividing the detection area 5 reduced by the lens 6 into 32 (vertical) × 32 (horizontal) areas.

  Based on the weak electromotive force, the two-dimensional thermopile array 2 can acquire temperature information for each area of the detected region 5.

  The temperature information for each area of the detection area 5 actually obtained by the two-dimensional thermopile array 2 is a temperature difference between the detection area 5 and the two-dimensional thermopile array 2 itself. The two-dimensional thermopile array 2 can know only the temperature difference from itself for each area of each divided detection target area 5.

  The temperature of the two-dimensional thermopile array 2 itself can be measured by the temperature sensor device 4.

  Accordingly, the microcomputer 9 calculates the temperature information for each area of the detected area 5 obtained by the two-dimensional thermopile array 2 to the temperature information from the temperature sensor device 4, thereby calculating 32 (vertical) × 32 of the detected area 5. Absolute temperature information for each area divided into (horizontal) can be obtained.

  The scan circuit 3 incorporated in the thermopile far infrared area sensor 1 receives a clock signal and a reset signal from the outside. Each time the reset signal is received, the scan circuit 3 initializes the value of the counter mounted in the scan circuit 3 and returns it to zero.

  The counter mounted in the scan circuit 3 is incremented by one in synchronization with the rising edge of the input clock signal.

  The area divided by 32 (vertical) × 32 (horizontal) of the two-dimensional thermopile array 2 has addresses in order from the upper left corner. The scan circuit 3 sequentially outputs the address value assigned to the two-dimensional thermopile array 2 to the two-dimensional thermopile array 2 by using the count value that increases one by one.

  The two-dimensional thermopile array 2 that has received the address outputs information on the temperature difference acquired sequentially for each corresponding area as a potential difference (voltage).

  The above-described potential difference is output from the P terminal and the N terminal that are output terminals of the thermopile far-infrared area sensor 1. The P terminal is a P channel terminal and the polarity means plus, and the N terminal is an N channel terminal and the polarity means minus.

The P terminal and N terminal output from the thermopile far infrared area sensor 1 are input to the amplifier 7. The amplifier 7 is a differential amplifier circuit, and according to the potential difference between the P terminal and the N terminal,
The potential difference is amplified and output from the amplifier 7 as an output signal.

  Since the electromotive force generated in the two-dimensional thermopile array 2 is weak, the amplifier 7 needs to amplify at a high magnification.

  The amplifier 7 of this embodiment amplifies the potential difference between the P terminal and the N terminal by several thousand times, and outputs the amplified difference to the low pass filter (LPF) 8.

  The LPF 8 is a low-pass filter composed of a resistor and a capacitor. The LPF 8 smoothes a rapidly increasing noise component in the signal included in the potential difference amplified by the amplifier 7 and outputs the smoothed noise component to the 12-bit A / D converter 10 in the microcomputer 9.

  The 12-bit A / D converter 10 converts the analog signal input from the LPF 8 into 12-bit digital data.

  Further, the temperature sensor device 4 outputs temperature information of the two-dimensional thermopile array 2 itself as a potential difference.

  The temperature information of the two-dimensional thermopile array 2 itself is input to the 12-bit A / D converter 11 and converted into 12-bit digital data by the 12-bit A / D converter 11.

  The CPU 12 indicates the temperature difference between the temperature information of the two-dimensional thermopile array 2 itself from the 12-bit A / D converter 11 and the two-dimensional thermopile array 2 for each divided area from the 12-bit A / D converter 10. The voltage output is calculated to obtain the absolute value of the temperature information for each area divided into 32 (vertical) × 32 (horizontal).

  Further, the CPU 12 stores the absolute value of the temperature information for each area in the SRAM 1 (14) via the CPU bus.

  The temperature of the detection area 5 is measured about three times per second, and the past three measurement results are stored in the SRAM 1 (14). In the SRAM 1 (14), whenever the temperature is newly measured, the oldest measurement result is continuously deleted and updated.

  Further, the temperature information for each 32 × 32 area measured at one time is called one frame and is collectively processed as one information unit.

  The absolute value of the temperature information for each area stored in the SRAM 1 (14) has a very large noise component removed by the LPF 8, but may still contain many noise components.

  Further, the CPU 12 removes the noise component based on the program stored in the PROM 13 in order to remove the noise component included in the SRAM 1 (14).

  A technique for removing noise components based on a program is generally called a digital filter, and has the convenience that filter characteristics can be adjusted simply by changing the contents stored in the PROM 13. The program stored in the PROM 13 is shown in the flowchart of FIG.

  Details of the flowchart stored in the PROM 13 will be described with reference to FIG.

The CPU 12 captures area information of one frame from the SRAM 1 (14) via the CPU bus. (S100)
The reason for processing in units of one frame is that when area information is processed for each divided area, the CPU 12 is frequently required to access the SRAM 1 (14), and an excessive burden is placed on the CPU bus. It is.

The 9 × 3 pixels at the beginning of one frame are selected and arranged in descending order to calculate the median. (S200)
The area information in the middle of the 3 × 3 9 pixels is converted into the median value obtained in S200 and written to the SRAM 2 (15). (S300)
It is determined whether all pixels have been completed. (S400)
If all the pixels have not been completed (S400: NO), the next 3 × 3 9 pixels are selected. (S500)
When all the pixels are finished (S400: YES), the process is finished.

The operations of S200 and S300 will be specifically described with reference to FIG.
The top 3 × 3 9 pixels are selected from the 32 × 32 area information (one frame).

  Out of 9 pixels of 3 × 3, the left corner of the first row is 1 area, 2 areas, and 3 areas, the left corner of the second row is 4 areas, 5 areas, and 6 areas. There are 9 areas.

  Therefore, there are 5 areas in the middle. The area information of 5 areas is corrected based on the area information of 1 area to 4 areas and 6 area to 9 areas. In the example of FIG. 3, the area information is voltage data indicating the temperature for each area, and it can be seen that the area information of 5 areas is much higher than the area information of 80 and other areas.

  In the case of the present heat ray detector that measures the change in temperature, it is difficult to think of taking an extremely different value from the adjacent surrounding area. Therefore, when voltage data indicating the temperature of each adjacent area is extremely different, it is generally considered that noise is mixed.

  FIG. 5 is a flowchart showing a method for obtaining the median value from nine numerical values. The method for obtaining the median value from nine numerical values is to first obtain the smallest value from the nine values and remove the smallest value. Next, the smallest value is obtained from the eight, and the smallest value is removed. By repeating this operation, the smallest value out of the five can be obtained. The fifth smallest value among the nine is the median value.

n pieces of data are collected into an array. In this case, n represents an integer and starts with 9. (S10)
Arrange n data in ascending order. (S20)
The smallest data is removed from the n data. (S30)
Compare the number of data with 5. (S40)
If it is greater than 5 (S40: NO), the process returns to S10.

  If it is equal to 5 (S400: YES), 5 data are collected into an array. (S50).

Arrange 5 data in ascending order. (S60)
The smallest data is the median. (S70), the process ends.

  In the process of FIG. 3, first, the median value of the size is obtained from the temperature of each area from 1 area to 9 areas.

  By changing the information of the five areas to the median value, the noise of 80 mixed in the five areas can be removed.

  The changed area information is written in the SRAM 2 (15), and the SRAM 1 (14) in which the actually measured area information is stored is left as it is.

  These series of processes are shifted from the 3 × 3 9 pixels at the upper left corner of the screen to the right one by one in parallel. When you finish from the upper left corner to the upper right corner, move down one line in the upper left corner of the screen and move to the right one by one in parallel. Sequentially, it moves down by one line, reaches the last stage of the screen and ends.

  Further, the method of correcting the middle value of 9 pixels from a series of 3 × 3 9 pixels to the median value of 9 pixels cannot correct area information outside the screen. This is because 9 pixels cannot be acquired outside the screen. Therefore, the area outside the screen is area information including noise. When the area information including noise is not preferable, the outermost area information among the 32 × 32 area information of the entire screen is discarded. In that case, there is a demerit that the screen becomes 30 × 30 and the screen itself becomes narrow.

  Therefore, in the method shown in FIG. 4, the area information is also corrected on the outside of the screen. There are two methods for correcting the area information outside the screen.

  Of the two types of control, 1 is a four-corner control, and 2 × 2 four pixels are selected as shown in FIG. Among the 2 × 2 four pixels, the first stage left corner is one area and two areas, and the second stage left corner is three areas and four areas. The target for correcting the area information is one area, and the area information for one area is corrected based on the area information for two areas, three areas, and four areas.

  As before, voltage data indicating temperatures for each area from 1 area to 4 areas are arranged in descending order to determine the median value of the sizes.

  This time, the area information is an even number, and there is no median value. Since it is near the center, the second and third values are the median. When noise is mixed, an extremely large value is often mixed. Therefore, when there are two median values, it is often desirable to select a small value.

  Therefore, this time, the second value of the size is corrected to the area information of one area. As can be seen from FIG. 4, the noise of 90 mixed in one area can be removed.

  The remaining one of the two types of control is the control of the outer edge of the screen, and 2 × 3 6 pixels are selected as shown in FIG. Among the 2 × 3 6 pixels, the first-stage left corner is 1 area, 2 areas, and 3 areas, and the 2nd stage left corner is 4 areas, 5 areas, and 6 areas. The target for correcting the area information is two areas, and the area information of the two areas is corrected based on the area information of the first area, the third area, the fourth area, the fifth area, and the sixth area.

  As before, voltage data indicating temperatures for each area from 1 area to 6 areas are arranged in descending order to obtain a median value of the sizes.

  Similarly for the control of the outer edge of the screen, the area information is an even number, and there is no median value. Since it is near the center, the third and fourth values are the median. When there are two median values, it is preferable to select a smaller value, and therefore the third value is corrected to area information of two areas. As can be seen from FIG. 4, the noise of 90 mixed in the two areas can be removed.

  As shown in FIG. 4, the outer edge is controlled by 6 pixels of 2 (vertical) × 3 (horizontal) at the upper and lower ends. At the left end and the right end, there are 6 pixels of 3 (vertical) × 2 (horizontal). The control of 6 pixels of 3 × 2 at the left end and the right end is the same as the case of the upper end and the lower end, and only the vertical and horizontal sizes of the selected 6 pixels are different.

  If the specific method shown in FIGS. 3 and 4 is used, area information obtained by correcting all 32 × 32 area information (one frame) including the outside of the screen is prepared in the SRAM 2 (15). It will be.

  The reason why the area information stored in the SRAM 1 (14) is left as it is is that the area information itself is destroyed when correction is performed based on the corrected area information.

  For example, when there is a person in the detected area 5, the boundary line is not clear and blurs, so that a problem that the outline of the person cannot be specified occurs.

  In order to clearly see the boundary line, it is not preferable to perform correction using the corrected area information. That is, when correction is repeated, the information itself is destroyed.

  From the above, it is not desirable to make correction based on easily corrected area information. Therefore, an SRAM 2 (15) that requires an equivalent size of the SRAM 1 (14) is provided, the area information measured is left in the SRAM 1 (14), and the corrected area information is stored in the SRAM 2 (15). A distinction is made between SRAM1 (14) and SRAM2 (15).

  In FIG. 1, SRAM1 (14) and SRAM2 (15) are illustrated separately. In the memory used for the CPU, the entire memory is generally divided into several parts and managed. When access from the CPU to the memory is requested, one target section is selected from the set of partitioned memories based on the memory address information and the like, and reading or writing is executed. The memory division at this time is called a bank.

  The above bank may be used to divide the memory into two banks, each of which may be SRAM1 (14) and SRAM2 (15), and two SRAMs may be used.

  When this bank is used, a part of the built-in memory address decoder can be shared as compared with the case where the SRAM 1 (14) and the SRAM 2 (15) are individually provided. The chip area can be reduced.

  Data stored in the SRAM 2 (15) is output from the microcomputer 9 using the USB 16 and the UART 17. USB and UART are general interfaces, and the data stored in the SRAM 2 (15) can be obtained in the personal computer 18 and the fire and people are detected by displaying the obtained data on the personal computer screen. I can do it.

  As mentioned above, although embodiment of this invention was described concretely based on the embodiment, it is not limited to this and can be variously changed in the range which does not deviate from the summary.

It is a block diagram which shows the display signal processing apparatus which concerns on one Example of this invention. It is a flowchart figure which shows the display signal processing apparatus which concerns on one Example of this invention. It is a figure which shows correction | amendment of 3x3 9 pixels based on one Example of this invention. It is a figure which shows correction | amendment of the pixel of the screen outer side which concerns on one Example of this invention. It is a flowchart figure which calculates | requires a median from nine numerical values based on one Example of this invention.

Explanation of symbols

  1 Thermopile array, 2 Two-dimensional thermopile array, 3 Scan circuit, 4 Temperature sensor device.

Claims (14)

It has a light receiving unit including a plurality of light receiving units arranged in the row direction and the column direction,
A median is obtained from a first detection signal detected from a first unit of the plurality of light receiving units and a plurality of detection signals detected from a plurality of light receiving units adjacent to the first unit, and the median Is replaced with a detection signal of the first unit. A first detection signal detected from a first unit of the plurality of light receiving units; a plurality of detection signals detected from a plurality of light receiving units adjacent to the first unit; the first detection signal; A median value detection circuit for obtaining a median value from a plurality of detection signals, and a replacement control circuit for performing control for replacing the median value with the detection signal of the first unit,
The median value detection circuit obtains a detection signal having a lowest level from the first detection signal and the plurality of detection signals, and determines the smallest detection signal as the first detection signal and the plurality of detection signals. A display signal processing apparatus characterized in that the median value is obtained by performing a minimum value deleting operation to be removed from the display.   The display signal processing apparatus according to claim 2, wherein the median value is obtained by repeating the minimum value deleting operation.   The display signal processing apparatus according to claim 1, wherein the display signal processing apparatus is used in a heat ray detector. A light receiving unit including a plurality of light receiving units arranged in a row direction and a column direction;
A first memory for storing a first detection signal detected from a first unit of the plurality of light receiving units and a plurality of detection signals detected from a plurality of light receiving units adjacent to the first unit;
A median value detection circuit for obtaining a median value from the first detection signal and the plurality of detection signals obtained from the first memory, and a second memory for storing an output median value of the median value detection circuit. A display signal processing device.   The median value detection circuit obtains a detection signal having the lowest level from the first detection signal and the plurality of detection signals, and determines the smallest detection signal as the first detection signal and the plurality of detection signals. 6. The display signal processing apparatus according to claim 5, wherein the median value is obtained by performing a minimum value deleting operation to be removed from the display value.   The display signal processing apparatus according to claim 6, wherein the median value is obtained by repeating the minimum value deleting operation.   6. The display signal processing apparatus according to claim 5, wherein the display signal processing apparatus is used in a heat ray detector.   The median value detection circuit has eight units adjacent to the upper right, right side, lower right, right above, right below, upper left, left side, and lower left with the detection signal detected from the first unit and the first unit as the center. 6. The display signal processing device according to claim 2, wherein a value having the fifth magnitude is obtained from the nine detection signals detected from. The median value detection circuit has 8 units adjacent to the upper right, right side, lower right, directly above, directly below, upper left, left side, and lower left with the detection signal detected from the first unit and the first unit as the center. From the nine detection signals detected from the above, a value having the fifth magnitude is obtained,
3. The display signal processing apparatus according to claim 2, wherein the replacement control circuit replaces a detection signal detected from the first unit with the fifth value from the median value detection circuit.   3. The median detection circuit replaces a detection signal detected from the four corner units with a detection signal detected from three units adjacent to the four corner units. The display signal processing apparatus according to claim 5. The median value detection circuit is detected from any of the detection signals detected from the four corner units and three units of the upper, lower, left, right, diagonally upper, and diagonally lower sides adjacent to the four corner units. Find the second largest value from the detection signals,
3. The display signal processing apparatus according to claim 2, wherein the replacement control circuit replaces detection signals detected by the four corner units with the second value from the median value detection circuit.   In the median detection circuit, the detection signal detected from the unit present at the outermost edge other than the four corners is detected from the unit present at the outermost edge other than the four corners; 6. The display signal processing device according to claim 2, wherein the display signal processing device is replaced in accordance with detection signals detected from five units adjacent to a unit existing at an outermost edge other than a corner. The median value detection circuit includes a detection signal detected from an outermost unit other than the four corners, and a detection signal detected from a unit existing at an outermost edge other than the four corners. Alternatively, a value that is the third magnitude is obtained from six detection signals detected from any of the diagonally upper and diagonally five units,
3. The display according to claim 2, wherein the replacement control circuit replaces a value measured in an outermost unit other than the four corners with the third value from the median value detection circuit. Signal processing device.

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