JPH03110398A - Target detector - Google Patents

Abstract

PURPOSE:To effectively obtain the center of a body and to detect a target with high sensitivity by providing a filter in which first and second infrared ray filter units having transmission properties, corresponding to wavelength characteristics of an infrared ray to be radiated from the body of the target and an infrared ray to be radiated from discharge gas of the target, are alternately disposed at a predetermined time interval. CONSTITUTION:First and second infrared ray filters a1, a2 and b1, b2 are alternately disposed on an optical axis in a filter section 153, an infrared ray to be radiated from the body of a target and an infrared ray to be radiated from discharge gas are output in a time division manner, image signals of both the rays are obtained by a photoelectric converter 155, and then separated into the signal of the first filter and the signal of the second filter. Here, one signal is delayed, both the signals are added in synchronization with the other signal in an initial state that the target is disposed remotely to form a composite image signal, thereby raising its sensitivity. Thereafter, when the target area is increased larger than the area of a reference, a body image is identified from the signal of the first filter instead of the composite signal to obtain the center of the detected body image.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) This invention is used, for example, in a guidance device for a surface-to-air guided missile, by capturing an infrared image of a target and determining its center. The present invention relates to a target detection device that guides a guided missile toward a target.

(Prior Art) Generally, a target detection device used in a guidance device for a surface-to-air guided missile obtains an infrared image of a projectile target using an infrared imaging device, and processes this infrared image to identify the projectile target. I'm looking for the center point. In other words, is the guidance device controlled by the target detection device? 1? The guided missile is guided toward the center point, which allows the guided missile to hit the target.

If the target is a flying object with a jet engine, such as an aircraft, the wavelength characteristics of the infrared rays emitted from the heat of the aircraft and the wavelength characteristics of the infrared rays of the exhaust gas emitted from the jet engine are different, as shown in Figure 5. There is. Therefore, in conventional target detection devices, in order to detect targets located further away, infrared filters used in infrared imaging devices are used.
The detection sensitivity of the infrared imaging device is increased by using a filter having a characteristic 13 that transmits both the wavelength characteristic 11 of the aircraft body and the wavelength characteristic 12 of the exhaust gas.

However, in the conventional target detection device as described above,
As shown in Fig. 6, the infrared image obtained by the infrared imaging device includes the image of the exhaust gas as well as the image of the aircraft, so the calculated center point deviates from the actual center point of the aircraft. If it is located quite far away, there is not much of a problem, but as you get closer, the error ratio increases, and as the exhaust gas spreads out, the determined center point will deviate from the aircraft.

(Problems to be Solved by the Invention) As described above, in conventional target detection devices, when the target is a flying object that injects exhaust gas, the infrared wavelength characteristics of the aircraft and the exhaust gas are different, and the infrared imaging device Since the infrared filter used in this camera satisfies both characteristics, the infrared image taken by this imaging device includes not only the aircraft body but also the exhaust gas, so even if you find the center of the image, It shifts from the actual center of the aircraft.

Furthermore, if an infrared imaging device uses an infrared filter that only responds to the wavelength characteristics of the aircraft, the detection sensitivity will be extremely low, making it impossible to detect the target if it is located far away.

This invention was made to solve the above problems, and even if the target is to emit exhaust gas from the aircraft body,
To provide a target detection device capable of reliably finding the center of an aircraft body and detecting a target with good sensitivity even when the target is far away.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the target detection device according to the present invention captures infrared rays emitted from the eyes of the aircraft body spouting exhaust gas, and thereby A device for determining the center of the target by image processing the obtained infrared image, which includes a condensing optical system that focuses incident light in the direction of the target, and an infrared light emitted from the target aircraft. A first infrared filter having a transmission characteristic corresponding to the wavelength characteristic and a second infrared filter having a transmission characteristic corresponding to the wavelength characteristic of the infrared rays emitted from the target exhaust gas, a filter section in which the first and second infrared filters are arranged alternately at regular time intervals on the optical axis of transmitted light; and a photoelectric conversion section that enters the infrared rays that have passed through the filter section and converts them into an infrared image signal. , a separation circuit section that separates the output signal of the photoelectric conversion section into an image signal transmitted through the first infrared filter and an image signal transmitted through the second infrared filter; and a separation circuit section separated by the dividing circuit section. signal processing that selectively outputs either an image signal transmitted through the first infrared filter, or a composite image signal obtained by delaying one image signal, synchronizing it with the other image signal, and adding both signals; an image processing section that identifies a target image from the image signal selected by this signal processing section and determines the center of the detected target image; Particularly, it is characterized by comprising a switching control circuit unit that causes the signal processing unit to select the composite image signal when the area is larger than a reference area, and selects the image signal transmitted through the first infrared filter when the area is larger than a reference area. The filter section includes two each of the first and second infrared filters, and the same filters are arranged so as to face each other across the rotation axis and to be parallel to each other, and the rotation axis is connected to the light condensing filter. Placed perpendicular to the incident light on the incident path from the optical system to the infrared detection section,
It is characterized in that each infrared filter is sequentially rotated at regular intervals so that it is arranged perpendicular to the incident light on the incident path.

(Function) In the target detection device with the above configuration, the first and second infrared filters are arranged alternately on the optical axis in the filter section, taking into account that the infrared wavelength characteristics of the target aircraft and the exhaust gas are different. Then, the infrared rays emitted from the target aircraft and the infrared rays emitted from the exhaust gas are extracted in a time-sharing manner, and after obtaining image signals of both infrared rays in the photoelectric conversion section, an image when transmitted through the first infrared filter is obtained. The signal is separated into a signal and an image signal transmitted through the second infrared filter. Here, in the initial state where the target is far away, one image signal is delayed and synchronized with the other image signal, and both signals are added to create a composite image signal and increase the sensitivity. The target image is identified from the target image, and the center of the detected target image is determined. After that, when the target image becomes larger than the area of the base, the target image, that is, the aircraft image, is identified from the image signal transmitted through the first infrared filter instead of the composite image signal, and the center of the detected aircraft image is identified. seek.

As a filter part, by rotating an optical body in which each pair of first and second infrared filters are arranged in parallel and facing each other on the path of the incident light, infrared rays from the aircraft body and infrared rays from the exhaust gas are sequentially removed. can be obtained alternately.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration when the present invention is applied to a target detection device mounted on a guided missile, in which 14 is a dome formed on the warhead, 15 is an infrared imaging device, 16 is a signal processing device, and 17 is a dome formed on the warhead. The image processing device 18 is a switching control device.

In the infrared imaging device 15, the light incident from the dome 14 is collected by a first lens 151, further converted into parallel light by a second lens 152, and then passed through a filter section 153.
is incident on the This filter section 153 includes a pair of infrared filters al and a2 each having a first transmission wavelength band that matches the wavelength characteristics of the infrared rays emitted from the target aircraft, and a second infrared filter that matches the wavelength characteristics of the infrared rays emitted from the exhaust gas. a pair of infrared filters b that whiten the transmission wavelength band of
, b2 are arranged so as to face the rotation axis Ω and to be parallel to each other, and the rotation axis g is arranged perpendicular to the incident light on the infrared incident path, Each infrared filter a at predetermined intervals.

a2, bl, and bl are sequentially driven to rotate so that they are arranged perpendicular to the incident light on the incident path.

The infrared rays that have passed through this filter section 153 are focused by the third lens 154 onto the imaging surface of the imaging element 155. The imaging surface of the image sensor 155 is configured, for example, as shown in FIG. 2, by arranging a large number of photoelectric conversion elements in a straight line or by arranging a plurality of near arrays. The image signal obtained by this image sensor 155 is sent to the signal processing device 16.

In the signal processing device 16, the input imaging signal is sent to a separation circuit section 161. This separation circuit section 161 separates and outputs an infrared image signal transmitted through the infrared filter "l+a2" and an infrared image signal transmitted through bl, and the infrared image signal Sa when transmitted through al and a2 is added. The infrared image signal sb transmitted to the circuit section 162 and transmitted through b, , b2 is sent to the delay circuit section 163.The delay circuit section 163 delays the input sb image signal and converts it into Sa.
The delayed image signal Sb' is synchronized with the image signal, and the delayed image signal Sb' is sent to the adder circuit section 16 via the switch 164.
3 and added to the Sa image signal. The composite image signal obtained by this addition is sent to the image processing device 17.

This image processing device 17 identifies the target image from the input image signal, calculates its center point, and calculates the area of the target image. Information on the center point is stored in the guided missile steering mechanism (not shown). ) is used to determine the guidance direction of the guided missile, and area information is sent to the switching control device 18. This switching control device 18 closes the switch 164 when the inputted area information is less than a reference value and derives the output of the delay circuit section 163 to the addition circuit section 162, and when it is equal to or greater than the reference value, opens the switch 164 and delays the input area information. This controls the output of the circuit section 1.63 to be cut off.

The operation of the above configuration will be described below with reference to FIGS. 3 and 4.

First, when the loaded guided missile is directed toward the target and light in the target direction passes through the dome 14 and enters the infrared imaging device 15, the light passes through the first lens 151 and the second lens 1.
The light enters the filter section 153 via the filter 52 . In this filter section 153, as shown in FIG. 3, infrared filters aI+a2 having a transmission band matching near the peak of infrared wavelength retention 11 emitted from the target aircraft,
an infrared filter b having a transmission band matching near the peak of infrared wavelength retention 12 emitted from the target exhaust gas;
, , b2, arranged alternately on the optical axis. Therefore, the filter section 153 transmits infrared rays from the aircraft body when a1+a2 is arranged, and transmits infrared rays from the exhaust gas when b1+b2 is arranged. Therefore, the image sensor 15
5, the infrared rays from the aircraft body and the infrared rays from the exhaust gas are alternately imaged through the third lens 154.
This allows time-divisional output of the aircraft image signal and the exhaust gas image signal.

The infrared image signals of the aircraft body and exhaust gas that are time-divisionally output from the imaging device 15 in this manner are input to the signal processing section 16 . In this signal processing section 16, in the initial state,
After separating into an aircraft image signal Sa and an exhaust gas image signal sb in a separation circuit section 161 and synchronizing them in a delay circuit section 163,
The addition circuit section 1B2 performs addition processing to create a composite image signal Sa+Sb' of the aircraft body and exhaust gas. This increases the brightness of the image signal, thereby increasing sensitivity, and even when the target is far away, the image is small, and the level of light reception is low, the target image can be reliably captured. When this composite image signal is sent to the image processing device 17 and its center point is determined, it will be shifted from the center of only the aircraft body due to the influence of exhaust gas, but since the target is still far away, no problem will occur.

As the loaded guided missile approaches the target, the target image obtained by the image processing device 17 gradually becomes larger. Therefore, the image processing device 17 calculates the area of the target image, sends the calculation result to the switching control device 18, and when the calculation result exceeds a predetermined value, the switch 164 is opened and the addition circuit section
The output of 62 is assumed to be only the aircraft image signal Sa. As a result, the image processing device 17 can obtain an image of only the aircraft body a, as shown in FIG. 4, and its center point can be determined with high accuracy.

At this time, sensitivity decreases, but this is not a problem because sufficient brightness can be obtained as the target approaches.

Therefore, the target detection setup with the above configuration can combine the aircraft image signal and the exhaust gas image signal to increase sensitivity even when the target ejecting exhaust gas from the aircraft is far away, the image area is small, and the light reception level is low. This allows you to detect targets further away, and when the target approaches and an image of a certain area or larger can be obtained, only the aircraft image can be extracted, ensuring that the center of the aircraft is accurately detected. You can ask for it.

Note that this invention is not limited to the above embodiments,
For example, the filter section 153 consists of one infrared filter of each characteristic, and these are combined at 90 degrees.
It may also be rotated around the rotation axis Ω. Further, the signal processing section 16 directly supplies the output of the delay circuit section 163 to the addition circuit section 162, and uses a selection switch instead of the switch 164 to selectively input the output of the separation circuit section 161 and the image processing device 7. Alternatively, the selection switch may be controlled by the output of the switching control device 18. It goes without saying that various other modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] As described above, according to the present invention, even if the target is one that spews exhaust gas from the aircraft, the center of the aircraft can be reliably determined, and even if the target is far away, the center of the aircraft can be determined with high sensitivity. A target detection device capable of detecting a target can be provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a target detection device according to the present invention, FIG. 2 is a diagram showing the structure of an image sensor of the same embodiment,
FIG. 3 is a characteristic diagram showing the characteristics of the filter section of the same embodiment, FIG. 4 is a diagram for explaining the operation of the same embodiment, and FIG. 5 is a characteristic diagram showing the characteristics of the filter section of the conventional target detection device. 6 are diagrams for explaining the operation of the conventional device.

Claims (2)

[Claims] (1) In a target detection device that captures infrared rays emitted from a target emitting exhaust gas from the aircraft, and processes the obtained infrared image to determine the center of the target, the device points in the direction where the target is located. a first infrared filter having transmission characteristics corresponding to wavelength characteristics of infrared rays emitted from the target aircraft; and a wavelength of infrared rays emitted from the target exhaust gas. and a second infrared filter having transmission characteristics corresponding to the characteristics, and the first infrared filter is provided on the optical axis of the transmitted light of the condensing optical system.
a filter section in which second infrared filters are arranged alternately at regular time intervals; a photoelectric conversion section that converts the infrared rays transmitted through the filter section into an infrared image signal; and a photoelectric conversion section that converts the output signal of the photoelectric conversion section into an infrared image signal a separation circuit unit that separates an image signal when transmitted through the first infrared filter and an image signal when transmitted through the second infrared filter; and an image signal when transmitted through the first infrared filter separated by the separation circuit unit; a signal processing section that selectively outputs either the image signal or a composite image signal obtained by delaying one image signal and synchronizing it with the other image signal and adding both signals; an image processing section that identifies a target image from an image signal and finds the center of the detected target image; and when the target image detected by the image processing section is smaller than a reference area, the composite image signal is sent to the signal processing section. and a switching control circuit unit that selects an image signal transmitted through the first infrared filter when the area is larger than a reference area. (2) The filter section includes two each of the first and second infrared filters, and the same filters are arranged so as to face each other across the rotation axis and to be parallel to each other, and the rotation axis is arranged perpendicular to the incident light on the incident path from the condensing optical system to the infrared detection unit,
2. The target detection device according to claim 1, wherein each infrared filter is sequentially rotated at regular intervals so as to be disposed perpendicular to the incident light on the incident path.