JPS5952384B2 - infrared tracking device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rosette-scan type infrared tracking device that scans a field of view in a rosette pattern to search for and detect a target. It is related to.

First, target detection in a rosette scan type infrared tracking device that has been used conventionally will be explained with reference to FIG.

In FIG. 1, 1 is a dome, 2 is a primary mirror, 3 is a secondary mirror, 4 is a wedge, 5 is a detector, 6 is an amplifier, 7 is a filter, 8 is an automatic gain controller, 9 is a comparator, 10 is a pickup sensor, 11 is a tracking signal generator, and 12 is a rotating shaft.

FIG. 2 is a diagram for explaining the operation of the apparatus shown in FIG. 1, and is a diagram showing a scanning locus A of the visual field.

In such a configuration, infrared radiation from the target passes through the dome 1, is reflected by the primary mirror 2 and the secondary mirror 3, passes through the wedge 4, and enters the detector 5.

Now, a condition between the apex angle of the wedge 4, the inclination angle of the secondary mirror 3 placed inclined with respect to the rotation axis 12, and the relative positional interval thereof is satisfied, and the wedge 4 and the secondary mirror 3
When the ratio of the rotational speeds around the rotation axis 12 reaches a certain value, the field of view is scanned in a rosette pattern along a scanning locus A as shown in FIG.

If the instantaneous field of view B shown in Figure 2 is selected, the scanning field of view C will be scanned almost completely, and if there is a target within the scanning field of view C, there will always be red light from the target during one period of the rosette scan. The externally emitted light enters the detector 5, and an output signal is obtained.

This output signal is amplified by an amplifier 6 and a filter 7
, and then input to a comparator 9 after passing through an automatic gain controller 8.

When the output signal level of the automatic gain controller 8 becomes larger than the threshold value set by the comparator 9, a target captured within the scanning field of view C is detected.

Furthermore, in order to know the position of the detected target within the scanning field of view C, pickup sensors 10a and 10 extract signals synchronized with the rotation of the secondary mirror 3 and the wedge 4.
Using the output of b, X of the scanning trajectory A shown in FIG.
The Y coordinate component is generated by the tracking signal generator 11, and the values of the X and Y coordinates when the output of the comparator 9 is obtained are obtained as the output of the tracking signal generator 11.

By the way, the scanning speed on the scanning locus C shown in FIG. 2 is increased.

Generally, the bandwidth of the filter 7 is determined by having a certain relationship with the dwell time determined by the scanning speed.
/N is optimized.

Therefore, in the rosette scan method, the optimum bandwidth of the filter 7 changes depending on the scanning radius.

FIG. 3 shows an example of the relationship between the optimum bandwidth (relative value) and the scanning radius R when the end of the scanning field of view C is normalized as the scanning radius 1, and the above is clearly understood.

In the rosette scan type infrared tracking device that has been used in the past, the bandwidth of the filter has been set to the optimum bandwidth at the center of the field of view, that is, when the scanning radius is zero.

As a result, S within approximately 70% of the scanning field of view C
Although the S/N ratio does not deteriorate significantly, there is a drawback that the S/N ratio is not optimized in areas where the scanning radius is large.

Therefore, in order to improve these points, the present invention provides an amplifier 6.
By connecting several filters with different bandwidths in parallel to the output of the C, or by changing the filter bandwidth along with the scanning radius, the S/N ratio can be optimized over the entire scanning field of view C, and the target detection sensitivity can be achieved. An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 4 is a diagram showing an embodiment of the present invention, 7a,
7b, 7n are filters, 8a, 8b,...8n
is an automatic gain controller, 9a, 9b, . . . 9n is a comparator,
13 is an OR circuit.

To explain the operation now, as an example, the filter 7a,
The scanning radius shown in FIG. 3 for the band widths of 7b...7n is 1.0. 0. 8. 0. 6°..., 0
It is assumed that the optimal bandwidth is set when , and the signal output from the target is obtained when the scanning radius is 0.8.

Since each filter 7a, 7b...7n is connected in parallel to the output of the amplifier 6, when the signal output is sufficiently large, pulse outputs can be obtained from all the comparators 9a, 9b...9n.

Therefore, a pulse output 1 is also obtained from the output of the OR circuit 13, indicating that the target has been detected.

On the other hand, when the signal output is small, the output S of the filter 7b is set to the optimum bandwidth when the scanning radius is 0.8.
/N are other filters 7a and 7c.

..., the pulse output is obtained only from the output of the comparator 9b, and it can be seen that the target is detected as the output of the OR circuit.

In addition, if the signal output from the target is obtained when the scanning radius is 0 (zero), if the signal output is small, the filter 7n is set to the optimal bandwidth when the scanning radius is 0 (zero). A pulse output is obtained only from the connected comparator 9n, and the target is detected.

As described above, the present invention provides filters 7a whose bandwidths are set to optimal bandwidths for each scanning radius;
7b...7n in parallel with the output of the amplifier 6 has the effect of improving the ability to detect targets within the scanning field of view C.

FIG. 5 is a diagram showing another embodiment of the present invention, in which a filter 7 and a controller 14 are used in place of the filters 7a, 7b, . . . , 7n of FIG.

As an input to the controller 14, a signal proportional to the scanning radius, which changes every moment, obtained from the tracking signal generator 11 is used.

Based on this input signal, the controller 14 controls the bandwidth of the filter 7 so that it becomes the optimal bandwidth corresponding to each scanning radius as shown in FIG.

In this way, the filter 7 can perform optimal signal processing no matter what signal output is obtained from the target located at any scanning radius within the field of view as the output of the amplifier 6.

As described above, the present invention has the effect that the ability to detect a target over the scanning field of view C is improved by connecting the filter 7 whose bandwidth changes with the scanning radius to the output of the amplifier 6.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a conventional infrared tracking device related to target detection, FIGS. 2 and 3 are diagrams for explaining the device shown in FIG. 1, and FIG. 4 is an embodiment of the present invention. FIG. 5 is a schematic diagram showing another embodiment of the present invention, in which 1 is a dome, 2 is a primary mirror, 3 is a secondary mirror, 4 is a wedge,
5 is a detector, 6 is an amplifier, 7 is a filter, 8 is an automatic gain controller, 9 is a comparator, 10 is a pickup sensor, 11
is a tracking signal generator, 12 is a rotating shaft, 13 is an OR circuit, 1
4 is a controller, A is a scanning trajectory, B is an instantaneous field of view, and C is a scanning field of view. In the drawings, the same or corresponding parts are designated by the same reference numerals.

Claims (1)

[Claims] 1. A target is searched and detected by scanning the field of view in a rosette pattern, and the output signal of the detector obtained from the target captured within the field of view is input to a filter, and the output signal of the filter is 1. An infrared tracking device configured to detect a target from the detector, characterized in that filters having several different bandwidths are connected in parallel to the output end of the detector. 2 Search and detect a target by scanning the field of view in a rosette pattern, input the output signal of the detector obtained from the target captured within the field of view to a filter, and detect the target from the output signal of the filter. 1. An infrared tracking device configured as described above, characterized in that a filter whose bandwidth changes with the scanning radius of the field of view is connected to the output end of the detector.