JPH06174828A - Target detecting device - Google Patents

Abstract

PURPOSE:To quickly detect a target without influence of an obstacle by multiplying detection output of a near infrared ray image of the target by a predetermined factor, and subtracting the product from detection output of a far infrared ray image. CONSTITUTION:An image at an upper half (thin thickness part) of a convex lens 1 is detected by a near infrared ray detector 2 while an image at a lower half (thick thickness part) thereof is detected by a far infrared ray detector 3, and they are sent to a subtractor 4. In the subtractor 4, output 2s of the near infrared ray detector 2 is multiplied by a predetermined factor according to difference of infrared ray characteristics between a target and an adjacent obstacle, the product is subtracted from output 3s of the far infrared ray detector 3 so as to suppress output of the obstacle not more than a threshold value and make output of the target not less than a threshold value, and the result is sent to an image processor 5. The image processor 5 conducts image processing and outputs an image of the target as a signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a target detecting device used for a flying object or the like.

[0002]

2. Description of the Related Art A conventional infrared target detecting apparatus obtains a temporal change rate of luminance of an object in a detection screen, and when it is equal to or more than a preset threshold value, the object is determined to be an infrared interference object. Then, a mask is placed on the position where the object exists on the detection screen to eliminate the infrared interference object.

[0003]

The flying object using the above-mentioned conventional infrared target detecting device as a seeker is about to fly toward the target, and the infrared obstructing object is also moving spatially. Therefore, the infrared obstructing object moves on the detecting screen, and the mask cannot be said to be effective in eliminating the infrared obstructing object. Further, since the radiant energy of the infrared obstructing object may fluctuate with time, it was uncertain to mask the infrared obstructing object with the temporal change rate of luminance.

[0004]

The present invention takes the following means in order to solve the above problems.

That is, as a target detecting device, a lens means directed to a target object and forming a far infrared image and a near infrared image, respectively, and a far infrared detecting means for detecting the far infrared image and the near infrared image of the lens means, respectively, Near-infrared detecting means, subtracting means for receiving the outputs of the far-infrared detecting means and near-infrared detecting means, multiplying the output of the near-infrared detecting means by a predetermined coefficient, and subtracting from the output of the far-infrared detecting means, Image processing means for receiving the output of the subtraction means and outputting the image of the target.

[0006]

In the above means, the lens means forms a far infrared image and a near infrared image of the target. The far-infrared image and the near-infrared image are detected by the far-infrared detecting means and the near-infrared detecting means, and sent to the subtracting means. The subtracting means, after multiplying the output of the near-infrared detecting means by a predetermined coefficient due to the difference in infrared characteristics of the target object and the obstacles in the vicinity thereof,
Output from the far-infrared detector. Then, the infrared output from the obstruction becomes zero level. This output signal is arithmetically processed by the image processing means and output as an image signal of the target.

Therefore, the image signal of only the target is output in real time without being affected by the obstacles near the target.

[0008]

【Example】

(1) A first embodiment of the present invention will be described with reference to FIGS.

In FIG. 1, a convex lens 1 whose upper half is thin and whose lower half is thick is provided toward a target (not shown).
The image formed by the upper half lens 1 is detected by the near infrared ray detector 2 and sent to the subtractor 4. The image formed by the lower half lens 1 is detected by the far infrared ray detector 3 and sent to the subtractor 4. The output of the subtractor 4 is sent to the image processor 5.

The subtractor 4 outputs the output 2 of the near infrared detector 2.
After multiplying S by a predetermined coefficient due to the difference in infrared characteristics between the target and the nearby obstacle, the output 3S of the far-infrared detector 3 is subtracted and output.

This point will be described in detail below.

The brightness of the object image detected by each infrared detector 2, 3 depends on the energy radiated by the object, that is, the temperature of the object, and the higher the temperature, the higher the brightness.
It is also assumed that the target is a ship and the obstacle is an infrared obstacle (infrared flare) emitted by the ship. Then the temperature of the target <
It becomes the temperature of the obstacle.

For example, assuming that the target temperature T _t = 40 ° C. and the obstacle temperature T _i = 80 ° C., the far infrared region (wavelength λ = 9 μ
The infrared radiation intensity (W / cm ² / μ) in the near infrared region (wavelength λ = about 4 μm) is calculated as shown in Table 1.

The brightness detected by each infrared detector 2 and 3 is
Since it is almost proportional to this radiant intensity, Table 1 may be considered as the ratio of luminance. Therefore, the output of each infrared detector 2 and 3 is shown in Table 2.
Becomes the value of.

[0015]

[Table 1]

[0016]

[Table 2] When 1.8 / 0.4 = 4.5 is used as the predetermined coefficient, the output of the subtractor 4 becomes 0.55 for the target object and 0 for the obstacle object.

More specifically, as shown in FIG. 2, the output obtained by scanning the target object a for a ship and the obstacle b is as shown in FIG. . The near-infrared detector 2 has a structure as shown in FIG. Further, the output of the subtractor 4 is as shown in FIG.

Therefore, the output of the obstacle b is suppressed below the threshold level, and the output of the target a exceeds the threshold level.

The output of the subtractor 4 is sent to the image processor 5,
Image processing is performed by the image processor 5, and the image of the target is output as a signal.

In this way, the target a can be detected in real time and output as an image signal without being affected by the obstacle b. (2) A second embodiment of the present invention will be described with reference to FIG. A synthetic lens 1a in which a thin annular convex lens is joined to the outer circumference of a thick convex lens is provided. Then, the far-infrared detector 3a is provided at the imaging position of the far-infrared ray of the target formed by the thick convex lens. Further, the near-infrared detector 2a is provided at the image forming position of the near-infrared ray of the target by the thin annular convex lens. Others are the same as the above (1). (3) A third embodiment of the present invention will be described with reference to FIG. The convex lens 1b is provided, and the far-infrared detector 3b is provided at the imaging position of the target with far-infrared rays. Further, the near infrared ray detector 2b is provided at the image forming position by the near infrared ray. Others are the same as the above (1).

[0021]

As described above, according to the present invention, two images in the far-infrared region and near-infrared region of the target are formed by the lens means and detected by the respective detecting means. After that, the subtraction means that utilizes the difference in the infrared characteristics between the target object and the obstruction suppresses the signal of the infrared obstruction. Then, the image is processed by the image processing means. Since these are processed in real time, the target can be detected at high speed without being affected by obstacles.

[Brief description of drawings]

FIG. 1 is a configuration system diagram of a first embodiment of the present invention.

2A, 2B, and 2C are explanatory views of the operation of the first embodiment (a), (b), and (c) of the present invention.

FIG. 3 is a configuration system diagram of a second embodiment of the present invention.

FIG. 4 is a structural system diagram of a third embodiment of the present invention.

[Explanation of symbols]

 1, 1a, 1b Lens 2, 2a, 2b Near infrared ray detector 3, 3a, 3b Far infrared ray detector 4 Subtractor 5 Image processor

Claims (1)

[Claims] 1. A lens means directed to a target object and forming a far infrared image and a near infrared image, respectively, and a far infrared detecting means and a near infrared detecting means for detecting the far infrared image and the near infrared image of the lens means, respectively. Receiving the outputs of the far-infrared detection means and the near-infrared detection means, multiplying the output of the near-infrared detection means by a predetermined coefficient, and subtracting the subtraction means and the output of the subtraction means from the output of the far-infrared detection means. An image processing unit that receives the image of the target and receives the image of the target.