JP2809744B2 - Target detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention is used, for example, in a guidance device for a surface-to-air missile, and captures an infrared image of a target to determine its center, and finds the center The present invention relates to a target detection device that guides a guided bullet toward a target.

(Prior Art) In general, a target detecting device used in a guidance device for a ground-to-air guided missile obtains an infrared image of a projectile target using an infrared imaging device, and processes the infrared image to perform processing on the center of the projectile target. Seeking points. That is, the guidance device guides the guide bullet toward the center point obtained by the target detection device, and thereby hits the target bullet with the target.

Here, when a flying object having a jet engine such as an aircraft is the target, the wavelength characteristic of infrared rays emitted from the heat of the aircraft and the wavelength characteristic of infrared rays of exhaust gas emitted from the jet engine differ as shown in FIG. I have. Therefore, the conventional target detection device has a characteristic 13 that transmits both the wavelength characteristic 11 of the airframe and the wavelength characteristic 12 of the exhaust gas as an infrared filter used in the infrared imaging device in order to detect a target located farther away. The detection sensitivity of the infrared imaging device is increased by using an object.

However, in the conventional target detection device as described above, since the infrared image obtained by the infrared imaging device includes the image a of the body and the image b of the exhaust gas as shown in FIG. Is shifted from the center point of the aircraft. Therefore, when the target is located at a far distance, there is not much problem. However, as the approach gets closer, the ratio of the difference increases thereafter, and when the spread of the exhaust gas increases, the obtained center point deviates from expectations.

(Problems to be Solved by the Invention) As described above, in the conventional target detection device, when the target is a flying object that injects exhaust gas, the infrared wavelength characteristics of the airframe and the exhaust gas are different, and the infrared imaging device Since the infrared filter that satisfies both characteristics is used, the infrared image captured by this imaging device includes not only the body but also the exhaust gas portion. It deviates from the actual aircraft center.
Further, if an infrared filter corresponding to only the wavelength characteristic of the airframe is used for the infrared imaging device, the detection sensitivity becomes extremely low, and the detection becomes impossible when the target is located at a distant place.

The present invention has been made in order to solve the above-mentioned problem. Even if the target is to eject exhaust gas from the airframe, the center of the airframe can be reliably obtained, and even if the target is far away, the sensitivity can be improved. It is an object of the present invention to provide a target detection device capable of detecting a target well.

[Constitution of the Invention] (Means for Solving the Problems) In order to achieve the above object, a target detection device according to the present invention captures infrared rays radiated from a target that ejects exhaust gas from an airframe, and obtains the infrared rays. In a device for processing the obtained infrared image to determine the center of the target, a condensing optical system for imaging incident light in a direction in which the target exists, and a wavelength of infrared light emitted from the target body A first infrared filter having a transmission characteristic corresponding to the characteristic, and a second infrared filter having a transmission characteristic corresponding to a wavelength characteristic of infrared rays emitted from the target exhaust gas, A filter unit for alternately arranging the first and second infrared filters on the optical axis at regular time intervals, and converting the infrared light transmitted through the filter unit into an infrared image signal by entering the infrared light An electric conversion unit, a separation circuit unit for separating an output signal of the photoelectric conversion unit into an image signal when transmitted through the first infrared filter and an image signal when transmitted through the second infrared filter, and the separation circuit One of the synthesized image signal obtained by adding the two signals in synchronization with the other image signal by delaying one of the image signals transmitted through the first infrared filter separated by the section and the other image signal is selectively output. A signal processing unit, an image processing unit that identifies a target image from the image signal selected by the signal processing unit, and obtains the center of the detected target image, and a target image detected by the image processing unit as a reference. A switching control circuit unit that causes the signal processing unit to select the composite image signal when the area is smaller than the area, and selects an image signal when transmitted through the first infrared filter when the area is larger than a reference area. Do .

In particular, the filter unit includes two first and second infrared filters, each being arranged so that the same filters face each other across a rotation axis and are parallel to each other. It is arranged so that it is perpendicular to the incident light on the incident path from the condenser optical system to the infrared detector, and each infrared filter is arranged at regular intervals so that it is perpendicular to the incident light on the incident path. It is characterized in that it is adapted to rotate.

(Operation) In the target detection device having the above-described configuration, attention is paid to the fact that the infrared wavelength characteristics of the target body and the exhaust gas are different, and the first and second infrared filters are alternately arranged on the optical axis in the filter section. Then, the infrared rays radiated from the target airframe and the infrared rays radiated from the exhaust gas are extracted in a time-division manner, and the photoelectric conversion unit obtains an image signal based on both infrared rays. And an image signal when transmitted through the second infrared filter. Here, in the initial state where the target is distant, one image signal is delayed, synchronized with the other image signal, and the two signals are added to create a composite image signal to increase the sensitivity. , The target image is identified, and the center of the detected target image is obtained. Thereafter, when the target image becomes larger than the reference area, the target image, that is, the body image is identified from the image signal at the time of transmission through the first infrared filter instead of the composite image signal, and the center of the detected body image is determined. Ask.

As a filter unit, by rotating an optical body in which a pair of first and second infrared filters are arranged in parallel to face each other on the path of incident light, infrared light from the airframe and infrared light from exhaust gas are sequentially emitted. Can be obtained alternately.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a configuration in a case where the present invention is applied to a target detection device mounted on a guide bullet, 14 is a dome formed on a warhead, 15 is an infrared imaging device, 16 is a signal processing device,
17, an image processing device; and 18, a switching control device.

In the infrared imaging device 15, the light incident from the dome 14 is collected by the first lens 151,
After being converted into parallel light at 52, the light enters the filter unit 153. The filter section 153 has a pair of infrared filters a ₁ and a ₂ each having a _first transmission wavelength band that matches the wavelength characteristics of the infrared light emitted from the target airframe, and matches the wavelength characteristics of the infrared light emitted from the exhaust gas. A pair of infrared filters b ₁ and b ₂ having a second transmission wavelength band are arranged so as to be opposed to and parallel to the rotation axis l, and the rotation axis l is connected to the infrared incident path. The infrared filters a ₁ , a ₂ and b ₁ , b ₂ are arranged at a predetermined interval on the incident path so as to be perpendicular to the incident light. It is driven to rotate.

The infrared light transmitted through the filter unit 153 is transmitted to the third lens 1
An image is formed on the image pickup surface of the image pickup element 155 by 54. The imaging surface of the imaging element 155 is configured by arranging a plurality of linear arrays in which a large number of photoelectric conversion elements are linearly arranged as shown in FIG. 2, for example. The image signal obtained by the image sensor 155 is sent to the signal processing device 16.

In the signal processing device 16, the input imaging signal is sent to the separation circuit unit 161. The separating circuit 161 as to demultiplex and output the image signals by the infrared transmitted through the image signal b _1, b ₂ by infrared rays passing thorough the infrared rays filter _{a 1, a 2, a 1} , a
₂ The infrared image signal Sa at the time of transmission is sent to the addition circuit unit 162,
The infrared image signal Sb transmitted through b ₁ and b ₂ is sent to the delay circuit unit 163. The delay circuit unit 163 delays the input Sb image signal and
The image signal Sb ', which is synchronized with the image signal a, is sent to the addition circuit unit 163 via the switch 164 and added to the Sa image signal. The composite image signal obtained by this addition is sent to the image processing device 17.

The image processing device 17 identifies a target image from an input image signal, calculates a center point of the target image, and calculates an area of the target image. Information on the center point is provided by a guidance bullet steering mechanism (not shown). ) To be used for determining the guide direction of the guide bullet, and the area information is sent to the switching control device 18. When the input area information is smaller than the reference value, the switching controller 18 closes the switch 164 and outputs the output of the delay circuit 163 to the addition circuit.
The control is performed so as to open the switch 164 and cut off the output of the delay circuit unit 163 when the value is equal to or more than the reference value.

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

First, when the mounted guided missile is directed in the target direction, and the light in the target direction is transmitted through the dome 14 and enters the infrared imaging device 15, the light is transmitted through the first lens 151 and the second lens 152. Incident on the filter unit 153. In this filter section 153, as shown in FIG. 3, infrared filters a ₁ and a ₂ having a transmission band matching the vicinity of the peak of the infrared wavelength characteristic 11 emitted from the target airframe, and emitted from the target exhaust gas Infrared filters b ₁ and b ₂ having a transmission band matching the vicinity of the peak of the infrared wavelength characteristic 12 are provided alternately on the optical axis. For this reason, the filter unit 153 transmits infrared rays from the airframe when a ₁ and a ₂ are arranged, and transmits infrared rays from exhaust gas when b ₁ and b ₂ are arranged. Therefore, the image sensor 155
The infrared rays from the airframe and the infrared rays from the exhaust gas are alternately imaged via the third lens 154, so that the airframe image signal and the exhaust gas image signal are output in a time-division manner.

In this way, the infrared image signals of the airframe and the exhaust gas output from the imaging device 15 in a time-sharing manner are input to the signal processing unit 16. In the signal processing unit 16, in the initial state, the separation circuit unit 161 separates the airframe image signal Sa and the exhaust gas image signal Sb, synchronizes them with the delay circuit unit 163, and then adds them.
And the combined image signal Sa + S of the body and exhaust gas
Create b ′. As a result, the sensitivity of the image signal is increased because the luminance of the image signal is increased, and the target image can be reliably captured even when the target is distant and the image is small and the light receiving level is low. When this synthesized image signal is sent to the image processing device 17 to find the center point, the center point is shifted from the center of only the body due to the influence of exhaust gas, but no problem occurs because the target is still far away.

As the loaded guided bullet approaches the target, the target image obtained by the image processing device 17 gradually increases. Therefore, in the image processing device 17, the area of the target image is calculated, the calculation result is sent to the switching control device 18, and when the calculation result becomes equal to or more than a predetermined value, the switch 164 is opened to output the output of the addition circuit portion 162. Only the body image signal Sa is assumed. As a result, the image processing device 17 obtains an image of only the body a as shown in FIG. 4, and the center point thereof can be obtained with high accuracy. At this time, the sensitivity is reduced, but sufficient luminance can be obtained by approaching the target, and there is no problem.

Therefore, the target detecting device having the above-described configuration combines the body image signal and the exhaust gas image signal to increase the sensitivity even when the target for ejecting the exhaust gas from the body is in a distant place, the image area is small, and the light receiving level is low. Since the target can be detected farther away, and if the target comes closer and an image with a certain area or more can be obtained, only the fuselage image can be taken out, so the center of the fuselage can be accurately determined with high accuracy be able to.

Note that the present invention is not limited to the above-described embodiment. For example, the filter unit 153 includes one infrared filter of each characteristic and combines them at 90 °.
You may make it rotate on the rotation axis l. Further, the signal processing unit 16 directly supplies the output of the delay circuit unit 163 to the addition circuit unit 162, and instead of the switch 164, the output of the separation circuit unit 161 and the output of the separation circuit unit 161 are selectively supplied to the image processing device 17 by a selection switch. Alternatively, the selection switch may be controlled by the output of the switching control device 18. In addition, it goes without saying that various modifications can be made without departing from the scope of the present invention.

[Effects of the Invention] As described above, according to the present invention, the center of the fuselage can be reliably obtained even when the target ejects exhaust gas from the fuselage, and the sensitivity is high even when the target is far away. A target detecting device capable of detecting a target can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a target detection device according to the present invention, FIG. 2 is a diagram showing a configuration of an image sensor of the embodiment,
FIG. 3 is a characteristic diagram showing the characteristics of the filter unit of the embodiment, FIG. 4 is a diagram for explaining the operation of the embodiment, and FIG. 5 is a characteristic diagram showing the characteristics of the filter unit of the conventional target detection device. FIG. 6 is a diagram for explaining the operation of the conventional device. 11 ... infrared wavelength characteristics of airframe, 12 ... infrared wavelength characteristics of exhaust gas, 14 ... dome, 15 ... infrared imaging device, 153 ...
Filter unit, 154: Image sensor, 16: Signal processing device, 1
61 separation circuit section, 162 addition circuit section, 163 delay circuit section, 164 switch, 17 image processing device, 18
Switching control device, Sa ... body image signal, Sb, Sb '... exhaust gas image signal.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F42B 15/01 F41G 7/22 G01S 3/782 H04N 7/18

Claims (2)

(57) [Claims] 1. A target detection device for capturing infrared rays emitted from a target that emits exhaust gas from an airframe and processing an infrared image obtained thereby to determine the center of the target. A focusing optical system that forms an image of incident light toward the target, a first infrared filter having a transmission characteristic corresponding to a wavelength characteristic of infrared light emitted from the target body, and infrared light emitted from the target exhaust gas A second infrared filter having a transmission characteristic corresponding to the wavelength characteristic of (a), and the first and second infrared filters are alternately arranged at a constant time interval on the transmitted light optical axis of the condensing optical system. A filter unit, and a photoelectric conversion unit that receives infrared light transmitted through the filter unit and converts the infrared light into an infrared image signal,
A separation circuit for separating the output signal of the photoelectric conversion unit into an image signal when transmitted through the first infrared filter and an image signal when transmitted through the second infrared filter; A signal processing unit for selectively outputting one of a combined image signal obtained by adding the two signals in synchronization with the other image signal by delaying the image signal transmitted through the first infrared filter and one image signal; An image processing unit that identifies a target image from the image signal selected by the signal processing unit and obtains the center of the detected target image, and the target image detected by the image processing unit is smaller than a reference area. A switching control circuit for causing a signal processing unit to select the synthesized image signal and, when the area is larger than a reference area, to select an image signal when transmitted through the first infrared filter; 2. The filter section comprises two first and second infrared filters, each being arranged so that the same filters are opposed to each other across a rotation axis and parallel to each other. The axis is arranged so as to be perpendicular to the incident light on the incident path from the condensing optical system to the infrared detector, and each infrared filter is sequentially arranged at regular intervals perpendicular to the incident light on the incident path. 2. The target detecting device according to claim 1, wherein the target detecting device is rotated so as to be rotated.