JPH03134525A - Infrared-ray image sensing apparatus - Google Patents

Abstract

PURPOSE:To obtain accurate temperature data by providing a means for correcting the output timing of a sample-hold pulse for measuring temperature by the rotation of a polygon mirror based on the rotating period of the polygon mirror. CONSTITUTION:Infrared rays from an object are reflected from a polygon mirror 5 and condensed on an infrared-ray detector 8 through an infrared-ray condenser lens 6 and a filter 7. The image data for one screen are stored in an image memory 27 for every one rotation of the polygon mirror 5. Then, a signal which is synchronized with a TV signal is inputted into an output address counter 32 from a TV-synchronizing-signal generator 31. Then, addresses for specifying the data in the memory 27 are sequentially generated in the counter 32. The output of the counter 32 are inputted into a gammaPROM 33 through the memory 27. In the ROM 33, correction is performed so that the temperature of the object is approximately proportional to the sensed amount of an image sensing person. The output of the ROM 33 corrected by rho is inputted into a synthesizing circuit 35 through a D/A converter 34 and synthesized with various kinds of character data generated in a character generating circuit 38. The result is displayed on a display device 36.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an infrared imaging device, and particularly to temperature information of a thermal image.

[Prior Art] Conventionally, an infrared imaging device captures infrared rays emitted from an object by reflecting and scanning them using a rotating polygon mirror, processes the signals, and obtains a thermal image displaying temperature information of the object. be. In this thermal image, a display device is known that displays temperature information on a desired location by operating a cursor or the like on the position of an index indicating a location on the subject where the temperature should be measured.

By the way, due to the difference in the rotation period of the polygon mirror, the timing of outputting the sample hold pulse for temperature measurement is also different, so there is not a reliable one-to-one correspondence between the index displayed on the screen and the location of the subject whose temperature is being measured. In some cases, accurate temperature information could not be obtained.

[Problem to be solved by the invention] The present invention solves the above problems, and even if there is a deviation in the rotation period of the polygon mirror, the index displayed on the screen and the temperature can be measured. It is an object of the present invention to provide an infrared imaging device that can obtain accurate temperature information by ensuring one-to-one correspondence between locations on a subject.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an infrared imaging device that obtains an infrared image of a subject from infrared rays emitted from the subject, which reflects infrared rays from the subject, and
A polygon mirror that rotates to scan observation points, an infrared detector that receives the infrared rays scanned by this polygon mirror, an image memory in which the output data of this detector is stored, and a polygon mirror in the image memory. A means for writing data other than the above output data, such as an index displayed on the screen, using a period when the object is not scanned, and a means for writing data other than the above output data, such as an index displayed on the screen, and measuring the temperature of a predetermined point within the entire observation field obtained by rotating the polygon mirror. means for outputting a sample hold pulse used in the determination;
and means for correcting the output timing of the sample and hold pulse based on the rotation period of the polygon mirror.

[Function] According to the above configuration, the timing of measuring the temperature of the subject is always set to 1 as the index specifying the temperature measurement point of the infrared image, in conjunction with the rotation speed of the polygon mirror or the like for scanning infrared rays.
Corrected to correspond to 1:1.

[Embodiment] FIG. 1 shows the overall configuration of an infrared photographing device according to an embodiment of the present invention.

In the figure, the infrared imaging device includes an imaging device main body 1,
It is composed of a grip 2, a CRT 3 which is an imaging display device, and a battery pack 4.

As shown in FIG. 2, the apparatus main body 1 has a built-in device for condensing infrared rays from a subject in order to obtain two-dimensional infrared information of the subject. This device consists of a polygon mirror 5 that reflects infrared rays from a subject, an infrared condensing lens 6 that collects the reflected infrared rays, a filter 7 that adjusts the amount of transmitted infrared rays that have been collected, and a filter that transmits through this filter 7. It is composed of a multi-element infrared detector 8 that outputs a signal according to the amount of infrared rays.

In this configuration, the infrared rays from the subject are
After being reflected by the infrared light, the light is focused onto an infrared detector 8 via an infrared condensing lens 6 and a filter 7 selected depending on the observation temperature range. The infrared detector 8 outputs a signal according to the amount of incident infrared light.

In addition, the polygon mirror 5 consists of six surfaces (9 to 14), for example,
Bands 1, 2 . It reflects infrared rays from ~n. These bands 1 to n include a large number of lines corresponding to the number of elements of the infrared detector 8,
When the polygon mirror 5 is rotated in one direction at a constant speed by a motor (not shown in FIG. 2), due to the rotation of one surface,
One band is scanned laterally. Further, since the adjacent surfaces of the polygon mirror 5 are tilted one after another at a certain angle, as the polygon mirror 5 rotates, the first surface (9) of the polygon mirror 5 changes the band l, The bands are scanned in the vertical direction, such that the second surface (10) is band 2, and so on.

In this way, horizontal and vertical scanning is performed, and the multi-element infrared detector 8 receives light one after another, thereby obtaining two-dimensional infrared information of the subject. Further, this two-dimensional infrared information is subjected to signal processing by a control device built into the main body 1 of the apparatus.

Next, the above control device will be explained with reference to the block diagram shown in FIG.

The control device is composed of a microcomputer, and is
An image input system that inputs dimensional infrared information, an image output system that obtains an infrared image from this information and displays that image on the CRT 3, and a control signal that calculates the temperature of the subject and adjusts the infrared image of the CRT. , and a processing system that outputs control signals to the entire device.

First, a circuit related to an input system for inputting the two-dimensional infrared information to the control device will be explained.

The two-dimensional infrared information signal obtained by the infrared detector 8 is
After being amplified by the preamplifier 18 and subjected to signal processing by the low-pass filter 19, the signal is input to the offset injection circuit 20. The offset injection circuit 20 includes a D/A converter 23 for the output signal from the low-pass filter 19, as will be described later.
The signal output from is injected. This allows the reference level of the output signal from the low-pass filter 19 to be changed freely. The output signal of the offset injection circuit 20 is input to the multiplexer 24, and signals corresponding to the number of elements of the infrared detector 8 are multiplexed one after another.
6 is input. The signal converted to digital 1 by the A/D converter 26 is guided to the image memory 27. On the other hand, the polygon mirror 5 is rotating, and the rotation is detected by the photosensor 28. The output of the photosensor 28 is input to an input address counter 30 via a timing generation circuit 29, and is regularly counted as the polygon mirror 5 rotates. This count value is supplied as the address of the image memory 27. And as mentioned above,
The digital signals guided to the image memory 27 are sequentially and regularly stored in accordance with this input address. In this way, one screen worth of image data is stored in the image memory 27 by one rotation of the polygon mirror 5. That will happen.

Next, a circuit related to an output system that reads data from the image memory 27 and outputs it to a display device as an infrared image will be described.

When a signal synchronized with the television signal from the television synchronization signal generator 31 is input to the output address counter 32, the output address counter 32 performs a process for specifying data in the image memory 27 based on the television synchronization signal. The output of the output address counter 32, which generates addresses one after another, is input to the address of the image memory 27, and the data of the designated address is read out one after another, and
33.

The γPROM 33 is arranged to perform γ correction.

- Numerically speaking, the temperature and energy of the subject, the voltage and brightness of the CRT screen, and the amount of incident light that enters the imager's eye and the amount of sensing are not directly proportional to each other. It is corrected so that the amount perceived by the person is almost directly proportional. γPR corrected in this way
The output of the OM 33 is input to the D/A converter 34 and converted into an analog quantity. The synthesis circuit 35 includes the D/A converter 3
The output of the 0 synthesis cycle f%35 for synthesizing the analog quantity obtained in step 4 and various character information generated by the character generation circuit 38 is input to the display W36 and displayed. Note that the output of the synthesis circuit 35 can be supplied to the outside as a decoded video signal 37, so for example, this decoded video signal 37 can be supplied to an external monitor television for display, or can be supplied to a VTR. You can then record it.

Next, a processing system that receives two-dimensional infrared information from the input system and adjusts an infrared image output to a display device by the output system will be described.

This processing system includes a central processing unit (CPU) 21 that calculates the temperature of the subject, outputs a control signal for adjusting the infrared image of the display device, and controls the entire device;
A character generation circuit 38 that generates character information to be displayed on a display device, a ROM 39 that stores a glodarum for executing operations of the CPU 21, a RAM 40 that temporarily stores data, and a clock TC 41 that provides time data to the CPU 21. , a key switch 42 that is manually operated by the CPU 21, and an E2PROM 53 that stores calibration information used by the CPU 21 to calculate the temperature.

Focus adjustment, offset, and gain adjustment by the processing system for adjusting the infrared image will be described below. These are used to notify the CPU that the various keys of the key switch 42 arranged as shown in FIG. 4 have been pressed.
21 is detected.

When the focus key is pressed, the CPU 21 detects this and outputs a motor drive signal to the focus lens drive circuit 43. The motor 49 is a motor for driving the infrared condensing lens 6, and when a motor drive signal is applied to the motor 49, the infrared condensing lens 6 is moved up and down, and focus adjustment is performed.

There are two types of offset adjustment: manual offset adjustment and automatic offset adjustment, and switching between them is done using the O/O offset adjustment described later.
This is done when the CPU 21 detects that the W key 58 has been pressed.

In the case of auto offset adjustment, the CPU 21
An auto signal is sent to the manual switching circuit 52 to enable the signal output from the comparison circuit 51. Comparison circuit 51
is configured such that a down signal is output when the signal level of the amplifier 25 is higher than a certain value Va, and an up signal is output when it is lower than a certain value vb, and Va and vb are determined by circuit constants. On the other hand, since a clock pulse is output from the CPU 21 to the counter 22, the input value of the D/A converter 23 changes, and the offset injection amount changes. In this way, in the case of auto offset adjustment, the amplifier 2
Feedback is applied so that the output level of No. 5 is between Va and vb, and the offset injection amount is automatically determined.

In the case of manual offset, the CPU 21
A manual signal is sent to the manual switching circuit 52 to invalidate the signal output from the comparison circuit 51, and CPtJ2
1 to enable the up/down signal to be sent to the counter 22. Then, since the CPtJ 21 outputs a clock pulse to the counter 22, the input value of the D/A converter 23 changes, and the offset injection amount changes.

Gain adjustment includes circuit gain switching and filter switching (hereinafter both switching will be collectively referred to as window adjustment). For circuit gain switching, CPtJ21
changes the gain of the amplifier 25. In filter switching, the CPU 21 outputs a range motor drive signal to the range filter drive circuit 44 to drive the motor 50 and switch the filter 7 to a filter with a different spectral transmittance, thereby reducing the amount of infrared rays incident on the infrared detector 8. Change the amount.

Next, a circuit related to a processing system that calculates the temperature of the subject from the signal obtained by the infrared detector 8 will be explained.

The output signal of the preamplifier 18 is sent to the sample hold circuit 4.
5 and is sampled by a sampling signal from the CPU 21. The sampled and held signal is input to multiplexer 47. On the other hand, from the infrared detector 8, a signal corresponding to the temperature of the detector 8's self-tusk, a signal regarding sensitivity, and a temperature sensing element 46 built into the device are transmitted.
The output signal of is input to the multiplexer 47. These three signals are multiplexed one after another and the A/D
It is input to the converter 48, converted into a digital quantity, and sent to the CPU.
21. The CPU 21 calculates the temperature of the object based on these three digital quantities. Temperature calculations of 0 or more are executed when the F/M-1r- located on the key switch 42, which will be described later, is pressed. be done.

Next, the key switch 42 will be explained with reference to FIG.

The key switch 42 includes a focus key for adjusting the focus of the infrared image, a key for offset adjustment or gain adjustment, and is wired to be connected to the CPU 21 . When any key of the key switches 42 is pressed, the lines intersecting at that position become conductive. C
Set 01 of PU21 to HIGH and check the levels of ■1 to I4.

In order, set 02.03 to HIGH and similarly set 14 to I4.
Check the level and try a key scan.

Then, which key has been pressed is detected based on the combination of 0 and I that are HIGH. The functions of each of these keys will be explained below.

+ key - key; Change offset and window.

F key, N-Ir-; Adjust focus.

VTR key, outputs the VTR start/strag signal when using the VTR.

0/W=q-; Select whether to enable window adjustment using auto offset, enable manual offset adjustment, or enable window adjustment using manual offset.

W/B key: Select whether to display high temperature areas in white or black.

F/M key: Measures temperature, freezes the screen (hereinafter referred to as "freeze"), saves the temperature value to memory, and releases the freeze.

Power switch: Provided on the side panel, device main body 1
Turn on the power to ON10FF.

Mode key: Switches between the initial display screen and the infrared image adjustment screen.

Function key: Selects which setting value on the screen can be changed.

Up (Ir) and Down keys; Function keys change selected settings.

Next, a display example of the screen of the display device 36 will be explained.

Figures 6(a) to (C) show the initial display screen displayed when the power is turned on, and Figures 7(a) to (d)
shows the screen for adjusting the infrared image. The manner in which the screen display changes depending on the key operation will be explained later in the CPU2
It is described in the operation explanation by 1.

The characters displayed in each area of these screens will be explained in bullet points.

■...Additional lens information attached to the device.

■...Temperature unit.

■...Time.

■...Focus information. When the F key or N key is pressed, “
"F↑" or 'Fl' is displayed.

■...The value is changed from "1'° to "6" with the setting change of wind information 0 concave road gain. Also, by switching the range ilter, "H", p"M"e" It is changed to "L".

■・・・Offset information, “O” when auto offset
Displays FAM, “OFM” for manual offset
will be changed to Furthermore, when the up key or down key is pressed during manual offset to change the offset, "OFM↑1" or "OFM↓" is displayed.

■...Immunity (emissivity) ■...When displaying temperature values etc. saved in memory,
Select this “LIST” by pressing the function key,
Press the up or down key.

■...Indicates temperature measurement mode and temperature calculation value.

[Phase]...Indicates that recording is in progress.

O...Temperature measurement mode. S is the instantaneous value, AVl, AV2
indicates the average value, and PK indicates the peak mode.

Note that a gray scale and an offset indicator (FIG. 7(a)) are displayed in the left column of the drawing. Also,
In FIG. 7(b), the memory number, temperature measurement mode, emissivity, and temperature measurement value are shown in order from the left column.

Here, to explain the relationship between the above-mentioned key operations and the display screen, the photographer operates the power switch to
When the power is turned on, the initial display screen appears. CR
Look at T3, select the temperature unit for temperature measurement, and set the time. After completing this initial setting, press the mode key to move to the display for infrared image adjustment. On this display screen, the photographer adjusts focus and window to make one infrared image clear.

Regarding the gray scale and offset indicators shown in FIG. 7(a), a part of the image memory 27 other than the area storing infrared image data is allocated to each area, and data is stored using CPtJ. It can be obtained by writing.

The operation of the CPU 21 will be explained based on the flowchart of FIG. 5(a) showing the operation procedure.

When you turn on the power with the power key of the infrared imaging device 1,
Initialization of internal registers of CPU 21 and RAM 40, E2
Initialize the calibration information stored in the PROM 53 into the RAM 40 (#1), display the initial screen (#2), and use this screen to set the time and select the temperature unit. , use the function keys to make certain characters on the initial screen blink.

The settings of the blinking characters can be changed. for example,
In Figure 6(a), 'I NTERNALONLY' is flashing, and when you press the up or down key,
The blinking characters change to “WIDE,” etc. (#3), then check whether the mode key was pressed (#4),
When pressed, the screen changes to a screen for adjusting the infrared image (thermal image adjustment screen) (#5). That is, Fig. 6<a)
The screen changes to the screen shown in FIG. 7(a). On this infrared image adjustment screen, a specific character flashes to indicate which settings are currently settable (#6), i.e. whether the offset can be adjusted manually or whether the window is being adjusted. Inform the person taking the image whether it is possible to do so. For example, in FIG. 7(c), “OPM
" is flashing, indicating that the offset can now be adjusted manually, and in FIG. 7(d), H6" is flashing, indicating that the window can be adjusted.

Next, scan the key switch 42 to check whether any key has been pressed (#7), and if any key has been pressed, determine which key was pressed (#8).
The process corresponding to that key, which will be described later, is performed, and the process returns to #5, and the same steps are repeated. Also, if no key is pressed in #7, the process returns to #5.

If it is determined in #4 that the mode key is not pressed,
Check whether the function key, up key, or down key was pressed (#9>.

If it is pressed, change the setting of the display value on the initial display screen (#10), change the characters (#11), then return to #2, display the initial screen, and repeat the same steps. Repeat. Above #10. In the process #11, for example, if you press the function key, the screen shown in Figure 6 (
As shown in b), change the blinking characters from “WIDE” to “C”
, and then press the function key several times to make "30" blink, indicating the minutes of the time.
By pressing the up key, the blinking can be changed from "30" to "31" as shown in FIG. 6(c).

Incidentally, in #9, if none of the function key, up key, and down key is pressed, the process returns to #2 and the same steps are repeated.

If it is determined in #7 that no key has been pressed, the process returns to step 5, displays the infrared image adjustment screen, and repeats the same steps.

Next, each process after determining each key in #8 will be explained.

(1) If the F/M key is pressed, proceed to #12 and use the RA
It is checked whether the flag FRZ provided in M40 is 0''. If FRZ=O, it is changed to FRZ=2 (# 13), return to #5.

If FRZ is not “0” in #12, check whether FRZ=2 (#14); if FRZ=2, check F”R
Rewrite Z=1 (#15) and save the image memory 2 of the infrared image.
After freezing the screen by prohibiting writing to 7 and allowing only reading (#16), #5
Return to Also, if the determination in #14 is NO, FrtZ
Note that =1, FRZ=O is rewritten (#17), writing of the infrared image to the image memory 27 is permitted, and the screen is released from the frozen state (#18). After that, it is checked whether the F/M key has been pressed for a certain period of time (for example, 2 seconds) or not (#19), and if it has been pressed, the temperature calculated by the interrupt processing routine is saved in the RAM 40 (#19). -1
). Next, clear the temperature display value calculated and displayed in the interrupt process (#19-2>, then return to #5. Also, in #19, if it is not pressed for a certain period of time,
Clear the temperature display and return to #5.

<2) If the W/B key is pressed, proceed to #20 and press γ
The upper bits of PROM 33 are inverted.

The γPROM 33 has two tables, one for displaying the high temperature section in white and the other for displaying it in black, and these two tables are switched by inverting the upper bits. After this switching process, the process returns to #5.

(3) If the F key or N key is pressed, proceed to #21,
A focus signal is output and drives the infrared condensing lens 6. Then, in order to show on the screen that the F key and N key are pressed, characters are sent to the character generation circuit 38 and displayed on the screen (#22>, and then the F key and N key are pressed. Check whether the button is pressed (#23). If the button is pressed, the process returns to #21 and the focus signal continues to be output.

Continue, if not pressed, i.e. F-1r-N
When the key is released, the focus signal is stopped and the driving of the infrared condensing lens 6 is stopped.
Clear the character indicating that a key is pressed (#2
4). After that, return to #5.

<45 If the VTR key is pressed, proceed to #25 and V
It outputs a TR start/stop signal to start and stop recording on the VTR, and sends a character signal to the character generation circuit 38 to display it on the screen in order to notify whether or not recording is currently in progress. (#26), then return to #5.

(5) If the O/W key has been pressed, proceed to #27 and check whether the O/W key has been pressed for a certain period of time (for example, 2 seconds) or more. When pressed, switches the state of the current offset adjustment operation.

In other words, if it is currently in the auto-offset state,
A signal is output to the auto/manual switching circuit 52 so that the offset can be adjusted manually. If it is not in the auto-offset state, a signal is output to the circuit 52 so that it will be in the auto-offset state (#28).

Next, in #29, the flag OW FLAG provided in the RAM 40 is rewritten to indicate three states: an auto-offset state, a state in which the offset can be adjusted manually, and a state in which the window can be adjusted by manual offset. After that, change the characters (#29-1) and #5
Return to In addition, #28. In #29, the window is EI in auto offset state or manual offset state.
The flag OW FLAG is set according to whether the
Like the aforementioned flag FRZ, three states are expressed by changing its value, and each state is used at the time of determination.

Also, in #27, if the O/W key has not been pressed for a certain period of time, it is determined whether or not the auto-offset state is currently in place based on the OW FLAG (#27-1).
, if it is in the auto-offset state, no processing is performed and the process returns to #5. If it is not in the auto-offset state, in #29, rewrite the OW FLAG and change the characters on the screen in order to alternately switch between manual offset adjustment and manual offset window adjustment according to the switch operation. (#29-1) and return to #5. and,
In #6, based on the rewritten OW FLAG, a specific character is made to blink to inform the photographer whether the offset or window can be adjusted with the + key and the - key.

(6) + key If the - key is pressed, proceed to #30,
Based on the OW FLAG, it is checked whether offset or window is currently selected. If offset is selected, counter 22
The offset is changed by outputting tarokku (#31).

Then, in order to notify that the offset has been changed, a character signal is output to the character generation port W138 (#3
2), then continue to check whether the + key and - key are pressed (#33), and if they are pressed continuously, #3
Return to 1 and continue changing the offset. #33, +
When the key is released, changing the offset is stopped (#34), the characters indicating that the offset has been changed are cleared from the screen, and the process returns to #5.

Also, if window adjustment is selected in #30,
Proceed to #35 and change the window by switching the gain or range filter. Then, in order to change the character indicating window adjustment, a character signal is output to the character generation circuit 38 (#36). Next, continue to press the + key -
Check whether the key is pressed (#37), and if it is pressed, return to #35 to continue changing the window, and if it is not pressed continuously, that is, it is female, then change the window. Stop #38) and return to #5.

(7) If the up key or down key is pressed,
Proceed to #39 and check the flag DSP provided in the RAM 40.
Check whether the value of L is "0". The value of this flag DSP L depends on three states: whether the immiscibility value can be changed by operating the up or down key, whether the saved temperature value can be displayed, and whether the temperature measurement mode can be changed. 0, DSP
It is set as L=1 and DSP L=2. Therefore, if DSP L=O, the immiscibility value is changed #40), the value is sent to the character generation circuit, the characters on the screen are changed #4O-1), and then the process returns to #5.

On the other hand, if it is determined in #39 that the flag DSP L is not 0, check whether DSP L is 1 (#41).
, DSP t, = 1, displays the saved temperature value, etc. on the screen (#42) (Figure 7(b)), then checks whether the up or down key is pressed again. (#42-1), if not pressed, #42-1
Go back and wait until pressed. And when pressed, #
Return to 5.

Also, in #41, DSP L is not 1, that is, D
If it is determined that SP L=2, change the temperature measurement mode (#43>.Here, decide whether to calculate the temperature value as an instantaneous value or not, for a few seconds (for example, 0.5 seconds or 2 seconds). Let the photographer select whether to use the average value or the peak value. Then, in order to display this temperature measurement mode, a character is sent to the character generation circuit 38 #43-
1), return to #5.

(8) If the function key is pressed, proceed to #44 and use the up key or down key to check whether the immiscibility value can be changed, whether the saved temperature value can be displayed, and whether the temperature measurement mode can be changed. A flag DSP is provided in the RAM 40 to indicate the three states.
Change the value of L (#44). Thereafter, the process returns to #5, and in #6, based on the value of this flag DSP_L, specific characters are made to blink, thereby informing the imager of what processing can currently be performed using the up key or down key.

Next, the operation of interrupt processing will be explained using FIG. 5(b).

The polygon mirror rotates at a constant speed, but every time it rotates, it enters an interrupt process.0 When it enters an interrupt process, a flag is changed by pressing the F/M key. Check whether the value of FRZ is “2” (#
l-1). If the value of FRZ is “2”, preamplifier 1
In order to sample the signal output from 8, a sample pulse is output to the sample hold circuit 45 (#
■-2). Then, the sampled signal is A/D converted, and the sensitivity signal of the infrared detector 8 and the temperature sensing element 4 are
A/D converts the signal from 6 (#l-3), CPU2
1 includes these three converted digital signals, performs correction for temperature calculation based on these values (#l-4), and calculates the temperature value (#l-4). -5).

In order to display the calculated temperature value on the screen, a character signal is sent to the character generating circuit 38 (#1-6), and after completing the interrupt processing, the process returns to the original flowchart. Also, #I-
1, and if FRZ is not 2, the interrupt processing ends without performing the above processing.

Next, signal processing of the detector output used for temperature measurement will be explained.

In order to clarify the features of this embodiment, first, signal processing of the output of a conventional infrared detector will be explained based on FIGS. 8 to 11.

FIG. 8 shows an infrared detector corresponding to the infrared detector 8 in FIG. 3 (hereinafter, for convenience, corresponding parts are given the same numbers)
FIG. 2 is a block diagram showing a conventional configuration of a signal processing circuit related to a processing system that calculates the temperature of a subject from a signal obtained in the above.

The output signal of the detector 8 is amplified by a preamplifier 18, passes through a buffer 55, and is amplified again by amplifiers 56 and 57. With the clamp pulse from the clamp pulse circuit 58,
Switch SW3 is opened and closed, and the detector output signal from amplifier 57 is clamped to clamp potential ■2. clan 1
The detected detector output signal is input to the sample and hold circuit 45 via the buffer 59. The detector output signal clamped by a sample hold (S/H) pulse from the CPU 21 is sampled and held, passes through a multi-brephther 47, and is A/D converted by an A/D converter 48.

FIG. 9 is a timing chart showing the timing of the clamp pulse and the S/H pulse.

When the polygon 1115 rotates, n band clocks are generated. The clamp pulse is output from the clamp pulse circuit 58 when the chopper (disposed between the infrared condenser lens 6 and the filter, not shown in FIG. 3) is completely closed. This clamp pulse clamps the detector output to the clamp potential. Further, the S/H pulse is supplied by the CPU 21.

When determining the offset of the circuit, the CPU 21 outputs a clamp pulse, and by the time the chopper starts to open, S/
Outputs H pulse. When determining the energy of an object to be measured such as an object, the CPU 21 outputs an S/H pulse at the center of the band clock while scanning the center of the observation field. Now, the detector output at the center within the entire observation field is sampled and held, and the temperature at the center can be determined.

Next, the operation of the conventional sample hold will be explained based on FIGS. 10 and 11.

Both Figures 10 and 11 show the sample and hold circuit 45 in a steady state, but Figure 10 shows the sample and hold operation when the sample and hold circuit in Figure 8 does not have the resistor 60 that provides a time constant. FIG.

The clamped detector output is sampled and held at point A with S/H pulse 1 in order to find the offset of the circuit, and the offset voltage VA that has been sampled and held is A/D converted to find the offset AZD value. . Next, in order to find the energy of the object to be measured, the detector output clamped at point B by S/H pulse 2 is sampled and held, and this sampled and held energy voltage VB is A/D converted and the energy A/D value is determined.

The CPU 21 calculates ((energy A/D value)-(offset A/D value)) to obtain the temperature.

However, if high-frequency noise is superimposed on the clamped detector output, variations will occur in the offset voltage ■^ and energy voltage VB, which will cause variations in temperature values. In order to reduce variations in the offset voltage VA and energy voltage VB due to noise, it is conceivable to provide the sample and hold circuit 45 with a time constant. As shown in FIG. 8, a resistor 60 and a capacitor 6
When 1 is added, these become a kind of low-pass filter, so the offset voltage V^ and the energy voltage VB become more stable as the time constant becomes larger.

To explain the operation of the sample and hold circuit in Figure 8 using Figure 11, the clamped detector output is sampled and held at point A' or A'' at S/H pulse 1 in order to find the offset of the circuit. However, since it has a time constant, the offset voltage differs depending on the size of the time constant. When the time constant is large, the offset voltage is ■^', and when it is small, the offset voltage is VA''. The sampled and held offset voltages V^' and V'' are A/D converted to obtain an offset A/D value.

Next, in order to find the energy of the object to be measured, S/
The detector output clamped at point B' or B'' is sampled and held by H pulse 2, but like the offset voltage, this also depends on the magnitude of the time constant, and the energy voltage becomes VB' or VB''.

This sampled and held energy voltage VB, VB
'' is A/D converted to obtain the energy value.If the time constant is increased, the variations in the offset voltage and energy voltage will be reduced, but as can be seen from Figure 11, ((energy A/D value) -(Offset A/D value)
) becomes smaller as the time constant becomes larger. In other words, A
Variations in temperature values occur due to the influence of quantization errors of the /D converter. In particular, since the offset voltage is a small voltage, the variation in the calculated temperature becomes large due to the influence of the quantization error of the A/D converter.

In order to reduce the influence of the quantization error of the A/D converter, it is sufficient to average the offset A/D values.
After outputting the clamp pulse, it is difficult for the CPU 21 to output a plurality of S and /H pulses before the chopper starts to open due to processing time.

Next, the signal processing circuit related to the processing system for calculating the temperature of the object shown in FIG. 3 of this embodiment, which solves the above problems, will be explained in more detail based on FIGS. 12 to 14. explain.

FIG. 12 shows a configuration in which a switch SW1 and a switch SW2 controlled by the CPU 21 are added to the configuration shown in FIG.

When the CPU 21 turns on the switch SW2, the detector output is cut and the offset of the circuit can be determined. When the CPU 21 turns on the switch SW1, the detector output is input and the energy of the object to be measured can be determined. .

FIGS. 13 and 14 show the sample-and-hold operation of this embodiment, both when the sample-and-hold circuit 45 is in a steady state. In Fig. 13, the CPU 21 is set to switch S.
It is a diagram when the WI is turned on.

The output of the clamped buffer 59 is sampled and held at point β using an S/H pulse in order to determine the energy of the object to be measured, and this sampled and held energy voltage β is A/D converted and becomes the energy A. /D value is determined.

FIG. 14 is a diagram when CPtJ21 turns on switch SW2.

When CPtJ21 turns on switch SW2, the output from preamplifier 18 is cut off, and the input voltage of amplifier 56 is set to vl in order to offset the circuit. S/H
The clamp voltage is sampled and held at point α by the pulse, and this sampled and held clamp voltage becomes the offset voltage, which is A/D converted and offset A.
/D value is determined. This operation is repeated n times to find the average value of the offset A/D values. Then, from the energy A/D value of the energy voltage ■β already found, (
The temperature value is calculated by calculating (energy A/D value) - (average value of offset A/D values).

In this embodiment, the above-mentioned temperature measurement is performed during an interrupt process that occurs every time the polygon mirror 5 rotates once. This operation procedure is the first
This will be explained based on the flowchart in FIG.

When interrupt processing is started, it is checked whether the value of flag FRZ is 2 or not. If FRZ=2, it is checked whether the average of the offset values of the circuit has been calculated (#l-10). If not, the CPU 21 turns on the switch SW2 (#l-12), samples and holds the offset voltage using the S/H pulse, and converts it from A/D to the A/D converter 48.

This operation is repeated n times, averaged (moving average) using the data of the previous n times, and the average value of the offset A/D (a) is determined and saved in the RAM 40 (#l-13).

If the average of the offset A/D values has been found in #l-10, the CPU 21 turns on the switch SWI (#l-
11) Set the energy voltage corresponding to the energy of the object to be measured as S/) (sample and hold with a pulse #l-2)
, the sampled and held energy voltage is A/D converted by the A/D converter 48 (#l-3). Next, #I-4
The process proceeds to , and the above-described processing is performed, and in #■-5, (energy AZD value) - (average value of offset A/Dri) is calculated to calculate the temperature value. Also, in #-1,
If FRZ is not 2, the interrupt processing ends without performing the above processing.

In this way, when offsetting the circuit, the CPU 21 turns the switch SW2 to OFF regardless of whether the chopper is open or closed.
By doing this, the offset AZD value can be obtained, and the CPU
21 can output multiple S/H pulses, and offset A
/D values can be averaged.

Also, since the average value of the offset A/D values is first determined and then the energy A/D value is determined, even if the time constant is set large, the conventional ((energy A/D value) = ( Compared to the offset A/D value)),
((Energy A/D value) - (Average value of offset A/D values)) of this example found from FIGS. 13 and 14
The value of is larger, and the influence of the quantization error of the A/D converter is smaller.

Furthermore, if the pulse width of the S/H pulse is made sufficiently larger than the time constant of the sample and hold circuit 45 when calculating the offset A/D value, when an abnormal offset voltage due to noise etc. is sampled and held, it will become equal to the clamp voltage. Therefore, the average error of the offset A/D values is reduced.

Furthermore, when the temperature of the object to be measured is low, the energy voltage is low, and the variation in the energy A/D value due to the influence of quantization error in A/D conversion increases, increasing the display resolution. Taking processing time into consideration, if you calculate the temperature by taking a moving average of fewer times than the average number of offset A/D values, you can reduce the display resolution.
Variations in temperature values also become smaller.

Next, offset indicators and indexes are stored in the image memory 27.
The timing of writing to will be explained based on FIG. 16.

The input address counter 30 generates an address for writing infrared image data into the image memory 27, but also generates a signal to enable writing to the image memory 27, as shown in FIG. be done. ■、■
,■,...,■,■.

There are a total of n periods equal to the number of faces of the polygon mirror 5, and within each period, an address for infrared image data is generated and the image memory 27 is enabled for writing. Therefore, infrared image data is written into the image memory 27.

On the other hand, in FIG. 16, ■, ■, ■, . . . , ■, ■ are periods in which the polygon mirror is not scanning an object. Data other than infrared image data can be written using this period in which infrared image data is not written. Therefore, the CPU 21 may write the data to the image memory 27 using this period.

In this embodiment, the polygon mirror scans the object by using a free counter in the CPU 21 in the interrupt processing that occurs every time the polygon mirror rotates once to write the offset indicator and index to the image memory 27. Execute during periods when you are not. This process will be explained based on the flowchart shown in FIG. The index can be written at the time of temperature measurement, so as shown in FIG.
= 2 ($1-10>. Also, the offset indicator is written to the image memory 27 after calculating the address of the image memory 27 when changing the offset (#X-0t to #l- 03>, if the CPU 21 cannot write these data only within one period (for example, 0 interval), write the data in another period, i.e.,
It is also possible to use the periods ①, .

In this way, not only infrared image data but also data such as offset indicators and indexes can be written into the image memory 27.

Next, the relationship between the sample hold pulse output when measuring temperature and the displayed index will be explained using FIGS. 18 and 19.

The sample-and-hold pulse is a signal output to the sample-and-hold circuit 45 when determining the temperature at a specific central location within the entire observation field obtained by rotating the polygon mirror 5. As shown in FIG. 18, the multifaceted fJ! scans the center of the observation field! This sample-and-hold pulse is output when a particular plane of A5 scans a particular central part of the object within a period when the object is being scanned laterally. The output of the pulse is executed within an interrupt process that occurs every time the polygon mirror 5 rotates once. Input address counter 3
0, as shown in FIG.
It detects that the scanning of the previous plane has ended and starts interrupt processing. Therefore, the sample and hold pulse is output after a specific time has elapsed (this specific time varies depending on the rotation period of the polygon mirror 5. A configuration for correcting this will be described later) after entering the interrupt process. .

A free counter within the CPU 21 may be used to measure the passage of time.

Now, an index is displayed to show the photographer where the specific point where this sample-hold pulse is output is. As shown in FIG. 19, there is a one-to-one correspondence between the timing of displaying the index on the screen as an interrupted line at the center and the center of the index, so that a specific point in the infrared region in the image memory 27, i.e. , just write the data for displaying the index at the address corresponding to the position where the index is to be displayed.

By the way, although the polygon mirror 5 is driven by the motor 54, it cannot be expected that its rotation period will always be constant; for example, the rotation period will change due to a change in ambient temperature. Therefore, even if the period of the polygon mirror 5 changes, if the output timing of the sample and hold pulses is exactly the same before and after the change, the temperature at the location indicated by the above index will not be measured. , the measurement will be made at a location where the rotation period is shifted.

Therefore, the output timing of the sample and hold pulse is
Correction is made based on the rotation period of the polygon mirror 5.

The operation of correcting the output timing of the sample bold pulse will be described below based on the flowchart of FIG. 20.

As the above correction operation, #l-001 to #l-003 may be added before #I-1 in FIG. 5(b). When interrupt processing is started, the free counter in CPtJ21 is read and 1iiiNi is stored in R,'AM40. Then, the free counter value N i− read in the previous interrupt
1 and the free counter value Ni read by this interrupt
(#l-002) Next, from this difference, calculate the timing to output the sample bold pulse (#l-003). When the multifaceted HA 5 rotates at a specified period, N-Ni-1 is known, and when the period deviates, Ni - Ni-1 also deviates from the known value by the amount of deviation, so this It is determined how much the output timing should be corrected based on Ni-Ni-1.

In other words, Ni - Ni-1 X is obtained. Here, N: Number of counts required for one rotation when rotating at a specified period.

A: The number of counts from entering interrupt processing to outputting a sample hold pulse while rotating at a specified cycle.

Then, a sample bold pulse is output based on this timing.

Writing of index data to the image memory 27 is performed, for example, by F.
It is executed after it is determined that RG=2 and before outputting the sample hold pulse (#110), but it may be executed at any time as long as an infrared image is not being written.

Note that it is possible to rewrite the index data by the amount of deviation in the rotation period, but considering that the number of pixels in the horizontal direction is finite, it is better to correct the output timing of the sample and hold pulses. It can be adjusted and has an accurate one-to-one correspondence.

In this way, the index displayed on the screen can be accurately associated with the location of the object whose temperature is being measured, so accurate temperature information can be obtained.

[Effect of the Invention 1 As described above, according to the present invention, even if there is a deviation in the rotation period of the polygon mirror that scans infrared rays in an infrared imaging device, the index displayed on the screen displaying the thermal image and the Since the temperature is corrected so that there is an accurate one-to-one correspondence between the locations of the subject where the temperature is measured, the temperature of the indexed location is always measured and accurate temperature information of the subject can be obtained. .

[Brief explanation of the drawing]

Fig. 1 is an overall perspective view of an embodiment of the infrared imaging device of the present invention, Fig. 2 is a configuration diagram of an infrared condensing device that scans infrared rays from a subject in the same device, and Fig. 3 is an overall block diagram of the imaging device. 4 is a diagram showing the key connection wiring, FIG. 5 is a flowchart showing the overall operating procedure of the imaging device, FIGS. 6(a), (b), and (c) are diagrams showing the initial display screen, and FIG. 7(a), (b), (c), and (d) are diagrams showing the infrared insect adjustment screen, and FIG. 8 is a block diagram showing the conventional configuration of a signal processing circuit related to a processing system that calculates the temperature of the subject. Figure 9 is a timing chart showing the timing of the clamp pulse and sample hold pulse; Figure 10;
Figure 1 is a diagram showing the operation of a sample hold circuit with a conventional configuration, Figure 12 is a block diagram showing the configuration of this embodiment of the above signal processing, and Figures 13 and 14 are sample hold circuits of this embodiment. Figure 15 is a flowchart showing the temperature measurement operation procedure, Figure 16 is a diagram showing the timing of writing the offset indicator and index, Figure 17 is a diagram showing the timing of writing the offset indicator and index.
The figure is a flowchart showing the above writing operation procedure, No. 18.
The figure shows the relationship between sample and hold pulses and indicators,
FIG. 19 is a diagram showing indicators on the display screen, and FIG. 20 is a flowchart showing the operation procedure for correcting the output timing of the sample-and-hold pulse. 5... Polygon mirror, 6... Infrared condensing lens, 8...
Infrared detector, 21... CPU, 22... Counter, 27... Image memory, 29... Timing generation circuit, 30... Input address counter, 36... Display device, 40... RAM, 45... Sample hold circuit, 46... Temperature sensing element, 47... Multiplexer, 48... A/D converter, 54... Motor.

Claims (1)

[Claims] (1) In an infrared imaging device that obtains an infrared image of a subject from infrared rays emitted from the subject, there is a polygon mirror that reflects the infrared rays from the subject and rotates to scan an observation point; an infrared detector that receives infrared rays; an image memory in which the output data of this detector is stored; means for writing data other than the above output data; means for outputting a sample hold pulse used to obtain the temperature of a predetermined location within the entire observation field obtained by rotating the polygon mirror; An infrared imaging device comprising means for correcting output timing based on the rotation period of the polygon mirror.