JPH09304186A - Image stabilization system for infrared imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image stabilization system which holds a reference DC level to be constant by a method wherein an analog offset correction and a digital offset correction with reference to a change in room temperature are used jointly. SOLUTION: An offset processing operation as a coarse adjustment is executed to an output from an input part 2 by an analog offset signal 801 in an analog offset circuit 3. A digital offset circuit 5 executes a digital offset processing operation as a fine adjustment by a digital offset signal 7d, and it sends out an infrared sensor output. A room-temperature sensor 1 and a room-temperature- data detector 6 fetch temperature data in a place in which the temperature sensor 1 is arranged inside an apparatus, and the data are supplied to a CPU 7. The CPU 7 gently executes two offset corrections only when the relative deviation of the two room-temperature data exceeds a prescribed tolerance, a sensitive correction response is excluded, and the stabilization of the generation of an image is ensured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stabilization system for an infrared imager, and more particularly to a stabilization method for eliminating excessive sensitivity of room temperature fluctuation correction to image generation including a period from power-on to reaching a steady state. The present invention relates to a stabilization method for an infrared imaging device.

[0002]

2. Description of the Related Art When a thermal image of an object is generated by an infrared imaging device, a room temperature sensor is usually arranged at a predetermined position inside the device, and its acquisition temperature in a substantially saturated operating environment temperature is used as a reference temperature. We are using. Although the difference between the maximum temperature level and the minimum temperature level detected by the infrared sensor is constant, the reference temperature corresponding to room temperature fluctuates corresponding to the operating environment temperature. A so-called room temperature clamp level correction is performed on the detected temperature so as to make the room temperature fluctuation apparently zero, and a constant clamp level is always set corresponding to the room temperature.

FIG. 4 is a block diagram showing a conventional room temperature fluctuation correction method for an infrared image device. Amplifier 2 of input section 2
The infrared sensor input signal 201 amplified by 1 is set by the DC regenerator 22 as a clamp level as a DC reference potential whose level is constant regardless of the magnitude of the input amplitude. Input unit 2
Output enters the analog offset circuit 3 and the potential when an infrared sensor (not shown) of the same device scans in the vicinity of the room temperature sensor 1 arranged in the device is a predetermined value (clamp) corresponding to room temperature. DA) so that it becomes a level)
The analog offset signal is corrected by the analog voltage from the converter 8 and subjected to the analog offset processing. However, the accuracy (bit number) of the D / A converter 8 which is often not sufficiently high accuracy can be generally used for cost or other reasons, so that the residual error of the quantization step, that is, the minimum digit is neglected. There may be cases where it becomes impossible.

Therefore, a digital offset circuit 5 is provided next to the A / D converter 4 that digitizes and outputs the output of the analog offset circuit 3, and a digital offset signal as a digital correction signal from the CPU 9 is fed back to the digital offset circuit 5. , Enables fine correction up to the minimum bit. In order to realize such a fine correction, the room temperature data detector 6 detects the signal corresponding to the room temperature from the infrared sensor output signal 501 to obtain the base value.
It is supplied to the CPU 9 as 601. The CPU 9 has a built-in program including an offset correction processing logic in advance, and the correction content is switched according to the magnitude of the relative deviation between the actual room temperature data 101 and the base value 601 by the room temperature sensor 1 and the changing direction thereof, and analog Offset circuit 3
Alternatively, feedback control is performed to correct the room temperature fluctuation of the digital offset circuit 5.

In this way, a large error correction due to room temperature fluctuations is corrected by the analog offset circuit 3, and a small error remaining in the analog offset circuit 3 is corrected by feedback control in the digital offset circuit 5 to enable accurate temperature measurement. It is supposed that it can realize a new infrared image device.

[0006]

In the above-mentioned conventional room temperature fluctuation correction method for the infrared imager, the large deviation of the relative deviation between the room temperature data 101 and the base value 601 shown in FIG. 4 is roughly adjusted in the analog offset system. The offset amount is corrected by the fine adjustment in the digital offset system.

When fine adjustment is performed with the digital offset system, since the correction is made every moment so that the room temperature = base value, the base value 601 to be compared with the room temperature data 101.
However, even if it is used as an average value for each of the past several samples and the change is smoothed, the relative change due to the fluctuation of the noise component included in the infrared sensor output signal 501 and the change over time of the room temperature sensor itself. Whenever the base value 601 fluctuates with respect to the room temperature data 101 due to an increase in deviation or the like, offset correction is immediately executed in response to this fluctuation, which makes it difficult to stabilize the image.

Furthermore, until the infrared imager reaches a steady state after power is turned on, the infrared imager reaches a steady state with a change in temperature of the apparatus itself, so that an unstable image generation state cannot be avoided. There is a point.

An object of the present invention is to solve the above-mentioned problems,
An image stabilization method for an infrared imaging device that can fundamentally eliminate the instability of image generation caused by excessive sensitivity of offset correction processing response to room temperature changes, including the period from turning on the power to the device until reaching a steady state. To provide.

[0010]

The present invention has the following means in order to achieve the above object. That is, the configuration of the present invention relating to the image stabilization system of the infrared imager is to ensure the stability of image generation by eliminating the excessive sensitivity in the correction process of the DC reference potential variation accompanying the room temperature variation in the infrared imager. An image stabilization system for an infrared image device, comprising: (a) to (h) shown below. (A) Room temperature sensor that is installed inside the infrared imager and sends out room temperature data in digital format. (B) Receives an infrared sensor input signal scanned by the infrared sensor of the infrared imager, amplifies it, and outputs a constant DC signal. An input unit for setting a clamp level as a reference potential (c) An analog as a coarse adjustment of room temperature fluctuations, which receives the output of the input unit and holds the clamp level constant based on an analog analog offset signal received from the outside An analog offset circuit that performs offset processing and sends (d) The output of the analog offset circuit is used as an input,
A-D converter that digitizes and sends out with a predetermined number of bits (e) As fine adjustment of room temperature fluctuations remaining in the analog offset circuit based on a digital offset signal received from the outside, using the output of the A-D converter as an input Digital offset circuit which performs digital offset processing of and outputs as infrared sensor output signal (f) Room temperature data detection for detecting room temperature data from the infrared sensor output signal near the room temperature sensor scanned by the infrared sensor and outputting as a base value (G) Input the room temperature data output from the room temperature sensor and the base value output from the room temperature data detector, and based on the image stabilization processing logic included in the built-in program, the infrared image device is in a steady state from the time of power-on. To the room temperature fluctuation including the rising period until reaching Data only when the difference between the base value and the base value exceeds a predetermined allowable range, the digital value that should be assigned to one analog value as the analog unit amount is changed to allow the difference to gradually fall within the allowable range. A CPU that sends the analog offset signal and the digital offset signal in a digital format while controlling the overall operation while performing the stabilization processing that ensures the stabilization of image generation by performing the analog offset processing and the digital offset processing with respect to the fluctuation. (H) DA converter for analog-converting a digital analog offset signal sent from the CPU and sending it to the analog offset circuit

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An offset correction for correcting a room temperature of an infrared imager so as to keep a clamp level as a reference DC potential of an input signal constant is performed at a room temperature arranged inside an infrared imager. Relative to the room temperature data and the base value, from the viewpoint that the room temperature data acquired by the sensor and the base value obtained by scanning the vicinity of this room temperature sensor with the infrared sensor of the same device should originally be the same. The analog offset system corrects a portion with a large relative deviation so that the influence of the deviation is apparently zero, that is, coarse adjustment is performed, and the relative deviation remaining in this coarse adjustment is finely adjusted by the digital offset system. Is performed under the control of a program built in the CPU so as to perform feedback control so that the relative deviation becomes zero. By such clamp level correction, room temperature clamp level correction capable of always maintaining the DC reference potential with respect to the input infrared sensor signal at a desired constant state with respect to changes in room temperature is ensured, and high-precision infrared image becomes possible. Has been done.

However, in the conventional room temperature clamp level correction, since the room temperature data = base value is promptly corrected, the base value to be compared with the room temperature data is smoothed by averaging several samples. Even if it has been subjected to
Since the hypersensitive correction is executed in response to the increase in the relative deviation caused by the temporal change of the room temperature sensor, there is a problem that it is difficult to stabilize the image generation. Furthermore, until the infrared imager reaches a steady state after the power is turned on, the infrared imager reaches a steady state with a temperature change until reaching the temperature saturation of the device itself, which also causes instability of image generation. There is a problem.

According to the present invention, in order to eliminate the instability of image generation due to these two problems, the relative deviation between the room temperature data and the base value is analog, including the rising period until the apparatus reaches a steady state. For each of the output processing and the digital output processing, the offset correction is executed only when the preset allowable range is exceeded,
Also, it is 1 of the analog unit quantity in the offset correction processing.
It is an embodiment of the invention that the number of digits to be assigned to the analog value is increased to effectively slow the offset correction speed to a desired state and stabilize the image generation.

[0014]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an image stabilization system of an infrared image device according to an embodiment of the present invention. The embodiment shown in FIG. 1 is a room temperature sensor 1 placed at a proper position inside an infrared ray.
And an input unit 2 for inputting an infrared sensor input signal 201 in the vicinity of the room temperature sensor 1 scanned by an infrared sensor (not shown), amplifying it, and performing DC regeneration for setting a clamp level as a DC reference potential; An analog offset circuit 3 for performing offset processing, an A / D converter 4 for converting the output of the analog offset circuit 3 into a digital form, a digital offset circuit 5 for performing digital offset processing, and an infrared ray in a digital format output from the digital offset circuit 5. A room temperature data detector 6 that detects data related to room temperature from the sensor output signal 501 and a program that includes a predetermined image stabilization processing logic are built-in, and analog signals are output based on the relative deviation between the outputs of the room temperature sensor 1 and the room temperature data detector 6. Offset processing of the offset circuit 3 and the digital offset circuit 5 Comprising the CPU7 for sending the offset signals required, and a D-A converter 8 for supplying the output of the CPU7 the analog offset circuit 3 into analog into.

Next, the operation of this embodiment will be described.
When the infrared imager is in a steady state, the infrared sensor input signal 20 near the room temperature sensor 1 scanned by the infrared sensor 20
1 is amplified by the amplifier 21 of the input section 2, and the DC regenerator 2
In 2, the DC regeneration is performed in which the clamp level as the DC reference potential of the constant DC potential is set regardless of the magnitude of the signal amplitude, and the output thereof is supplied to the analog offset circuit 3.

The analog offset circuit 3 uses the analog offset signal 801 provided from the D / A converter 8 so that the potential when the infrared sensor scans the vicinity of the room temperature sensor 1 is a preset value corresponding to the room temperature. Coarse-adjusted analog offset processing is performed to achieve a certain clamp level, and as a result, the room temperature data 101 output by the room temperature sensor 1 and the base value output by the room temperature data detector 6
Most of the correction processing is performed to eliminate the relative deviation from 601.

In this case, the processing shown in FIG. 2 is executed in the analog output processing state. FIG. 2 is a diagram showing the first half of the video stabilization processing logic included in the built-in program of the CPU 7 of FIG. 1 according to a flowchart, and mainly shows a video stabilization processing flow relating to analog offset processing. C
Based on the magnitude relationship between the room temperature data recognized by the PU 7 and the base value, and the difference between the previous base value and the current base value is within the allowable range of 3 analog values, the digital value corresponding to 1 analog value is changed to perform the offset correction. It indicates that the desired slowing occurs.

The correction process in the analog output process stage is mainly executed for the apparent room temperature fluctuation in the rising period after the power is turned on until the steady state is reached. The output of the analog offset circuit 3 is next A
The signal is digitized by the -D converter 4, supplied to the digital offset circuit 5, finely adjusted by digital offset, and then output as an infrared sensor output signal 501.

The digital offset circuit 5 performs fine adjustment on the residual digitized component of the relative deviation remaining due to the coarse adjustment of the clamp level by the analog offset circuit 3 by C
Only when the residual digitized component exceeds a predetermined allowable range based on the digital offset signal 701 provided from the PU 7, the image stabilization processing logic included in the built-in program of the CPU 7 is executed.

That is, this fine adjustment is carried out only when the relative deviation between the room temperature data 101 and the base value 601 exceeds a predetermined allowable range, in accordance with the room temperature clamp level correction executed again under the control of the CPU 7. This eliminates the excessive sensitivity of correction to the occurrence of the relative deviation between the room temperature data 101 and the base value 601 and enables stable image generation.

In the present embodiment, the above-mentioned allowable range is set to 5 digits of the digital value of the relative deviation between the room temperature data 101 and the base value 601. How many digits this allowable range is, like the allowable range in the analog output processing described above, the operating specifications of the device, the number of quantization steps set based on the desired processing accuracy for the expected maximum relative deviation, and It is determined in advance in consideration of various conditions such as desired image generation stability.

Even if the relative deviation exceeds n digits (n = 6, 7, 8, ...), which exceeds 5 digits, the CPU 7 does not correct the n digits as they are, but gradually increases by one digit. Gradually, to eliminate the image instability caused by the sudden relative deviation response.

FIG. 3 is a diagram showing the latter half of the video stabilization processing logic included in the built-in program of the CPU 7 of FIG. 1 according to a flowchart, and mainly shows the video stabilization processing logic relating to digital offset processing. Based on this image stabilization processing logic, the instability of image generation due to the sensitive correspondence of the offset correction executed to make the difference between the room temperature data and the base value in the steady state of the apparatus zero is eliminated. In this case, the allowable range is the difference between the room temperature data and the base value within plus / minus 5 digits, and if the difference exceeds the allowable range, the difference between the room temperature data and the base value should be within the above 3 analog outputs. 1 Correct and set the digital value of the analog value pair. In this way, it is possible to greatly reduce the sensitivity of the offset processing response during the start-up and steady state of the apparatus, and to significantly improve the stability of image generation.

[0024]

As described above, according to the present invention, the relative difference between the room temperature data measured by the room temperature sensor and the actually measured room temperature data in order to keep the reference level constant corresponding to the room temperature fluctuation as the reference level, When performing offset correction by coarsely adjusted analog offset processing and finely adjusted digital offset processing, an allowable range is set for offset correction for room temperature fluctuations including the rising period of the equipment, and relative offset is exceeded. Only when a difference occurs, the corresponding digital value per analog value is changed and set so that the relative difference is converged within the allowable range, and the offset correction is performed gently, thereby significantly increasing the stability of image generation. Has the effect of being able to.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an image stabilization system of an infrared image device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a first half of a video stabilization processing logic included in a built-in program of a CPU 7 of FIG.

FIG. 3 is a diagram showing a second half of a video stabilization processing logic included in a built-in program of the CPU 7 of FIG. 1 in a flowchart.

FIG. 4 is a block diagram showing a configuration of a room temperature fluctuation correction method of a conventional infrared imaging device.

[Explanation of symbols]

 1 Room Temperature Sensor 2 Input Section 3 Analog Offset Circuit 4 AD Converter 5 Digital Offset Circuit 6 Room Temperature Data Detector 7 CPU 8 DA Converter 21 Amplifier 22 DC Regenerator

Claims (1)

[Claims] 1. An infrared ray having the following constitutions, wherein excessive sensitivity is eliminated in a correction process of a DC reference potential variation due to a room temperature variation in an infrared ray image device to secure a stable image generation. Video stabilization method for video equipment. (A) Room temperature sensor that is installed inside the infrared imager and sends out room temperature data in digital format. (B) Receives an infrared sensor input signal scanned by the infrared sensor of the infrared imager, amplifies it, and outputs a constant DC signal. An input unit for setting a clamp level as a reference potential (c) An analog as a coarse adjustment of room temperature fluctuations, which receives the output of the input unit and holds the clamp level constant based on an analog analog offset signal received from the outside An analog offset circuit that performs offset processing and sends (d) The output of the analog offset circuit is used as an input,
A-D converter that digitizes and sends out with a predetermined number of bits (e) As fine adjustment of room temperature fluctuations remaining in the analog offset circuit based on a digital offset signal received from the outside, using the output of the A-D converter as an input Digital offset circuit which performs digital offset processing of and outputs as infrared sensor output signal (f) Room temperature data detection for detecting room temperature data from the infrared sensor output signal near the room temperature sensor scanned by the infrared sensor and outputting as a base value (G) Input the room temperature data output from the room temperature sensor and the base value output from the room temperature data detector, and based on the image stabilization processing logic included in the built-in program, the infrared image device is in a steady state from the time of power-on. To the room temperature fluctuation including the rising period until reaching Data only when the difference between the base value and the base value exceeds a predetermined allowable range, the digital value that should be assigned to one analog value as the analog unit amount is changed to allow the difference to gradually fall within the allowable range. A CPU that sends the analog offset signal and the digital offset signal in a digital format while controlling the overall operation while performing the stabilization processing that ensures the stabilization of image generation by performing the analog offset processing and the digital offset processing with respect to the fluctuation. (H) DA converter for analog-converting a digital analog offset signal sent from the CPU and sending it to the analog offset circuit