JPS60164271A - Infrared homing apparatus - Google Patents

Abstract

PURPOSE:To improve the temperature resolving power with a reduction in the required frequency band of an amplifier by performing a horizontal scanning with the oscillation of a gimbal only, when searching a target. CONSTITUTION:Incident infrared rays are focused with an infrared dome 1 and an infrared ray scope 2 and reflected with a double-axis scanning mirror 3 for horizontal and vertical scannings. Infrared rays reflected with the scanning mirror 3 are sent to a signal processor 11 through a detector 6, a preamplifier 7, a multiplexer 8 and the like to automatically detect and track a target. The unit indicated by the dotted line 20 is carried on a gimbal driven by a gimbal driving section 13 and detects the angle of horizontal oscillation of the gimbal with respect to the machine body with a rotary encoder 14 to be fed to the signal processor 11. A target is searched by oscillating the gimbal to the right or left. Here, the 2-axis scanning mirror 3 stops scanning and restarts it to track the target after the discovery thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an infrared homing device in which an infrared imaging device is mounted on a gimbal and searches for and tracks a target by swinging the gimbal.

[Prior art]

In general, this type of device is difficult to distinguish the target from noise and make mistakes when tracking the target once it has been acquired (a higher signal-to-noise ratio is required to reliably detect the target. Sometimes it is desirable to have better temperature resolution than when tracking a target. However, in conventional devices of this kind, when searching for a target, images are taken using a scanning mirror in the same way as when tracking a target, and each imaged field is Therefore, when searching for a target, the same thermal resolution as when tracking the target could be obtained.

[Summary of the Invention J This invention was made for the purpose of improving the above drawbacks, and when searching for a target, horizontal scanning is not performed using a scanning mirror, but only by swinging the gimbal. As a result, filtering processing is performed in accordance with the required frequency band that is reduced to improve the temperature resolution.The drawings will be described in detail below.

[Embodiments of the invention]

FIG. 1 Q is a configuration diagram showing an embodiment of this invention, in which incident infrared light is focused by an infrared dome +lj and an infrared telescope (2), and scanned to form a screen in the horizontal direction. , and is also reflected by a two-axis scanning mirror (3) that scans for interlacing in the vertical direction.

At this time, the two-axis scanning mirror (3) is driven and controlled by a scanning mirror driver (4). The infrared light reflected by the two-axis scanning mirror (3) is imaged onto a one-dimensional array of infrared detectors (6) by an imaging optical system (5). Infrared detector (61
The signal of each detection element is amplified by a preamplifier (7), and the signal corresponding to each detection element is sequentially sampled by a multiplexer (8) and converted into a serial signal.

The serial signal output from the multiplexer undergoes automatic gain and DC level control in a post-amplifier (9), and is converted into a digital signal by a digital converter LII. The digital video signal is sent to a signal processor 0υ, where automatic target detection and target tracking are performed. All these timings are controlled by a synchronous controller u7J. On the other hand, the part surrounded by a dotted line in Figure 1 is mounted on a gimbal driven by a gimbal driver at 11 fathoms, and the horizontal swing angle of the gimbal with respect to the nine aircraft is detected by a rotary encoder circle and a signal processor Sent to Uυ. -Figure 2 shows the relationship between gimbal oscillation, vertical interlaced scanning and horizontal scanning of the two-axis scanning mirror, (a)
(b) shows the interlaced scanning of the two-axis scanning mirror, and (0) shows the horizontal scanning of the two-axis scanning A]. Shake your head left and right to search for your target. At this time, horizontal scanning of the two-axis scanning mirror is stopped, and interlacing is performed only in the vertical direction each time the gimbal swing direction changes in order to fill the gap between each detection element of the infrared detector. When a target is found by target search, the gimbal is pointed in the direction of the target.
The two-axis scanning mirror also starts scanning in the horizontal direction for normal imaging to track the target.

Generally, the temperature resolution of an infrared m-imager is inversely proportional to the square root of the frequency band of the amplifier, when other parameters remain unchanged. Now, assuming that the time it takes for a point in the field of view to be imaged on the infrared detector and to cross one detection element by scanning is τd, the required frequency band Δf of the device is expressed by the following equation.

Δf1 ・・・・・・・・・・・・・・・・・・
・・・・・・・・・il+−2τd Furthermore, the normal imaging with this type of imaging device is τ at the time
d is calculated by the following formula.

αη τd=1 ・・・・・・・・・・・・・・・・・・・・・
(2) where α: instantaneous field of view in the horizontal direction η: effective scanning efficiency in the horizontal direction of the scanning mirror θ: field of view in the horizontal direction F=field rate. Now, α=0.5 (mrad), η=Q
, 4.0=100 [mrad], ? = 60
(ilz), then 11), 121 Equation % Equation % On the other hand, τd when scanning is performed only by swinging the gimbal without scanning the scanning mirror in the horizontal direction when searching for a target is given by the following equation.

However, the angular velocity of the swing of β Nishinpal It is. Now, if β=50 ([/second]), then (1).

From equation (3), Δf=0.81 [K11z].

Now, when searching for a target and tracking a target, the frequency band of the preamplifier is changed to match the required frequency band.

As mentioned above, the temperature resolution of the device is inversely proportional to the square root of the frequency band of the amplifier, so the temperature resolution improves about four times when searching for a target compared to when tracking a target.

FIG. 3 shows an embodiment of the preamplifier, which is an amplifier for 1 cu corresponding to each detection element of an infrared detector. When searching for a target, switching transistor Q
is in the ON state, and the frequency band of the amplifier is as follows.

Δf:2πR(01+OO) ”””””””””””'
(41 However, it is assumed that the ON resistance of the transistor is sufficiently smaller than R. On the other hand, when tracking the target, the transistor Q
is turned off, and the frequency band of the amplifier is determined by the following formula: % Therefore, by turning on or off the transistor Q, the frequency band of the preamplifier can be switched.

In addition, although the case where the frequency band is changed by the grid amplifier has been described above, the temperature resolution can also be improved by digitally filtering after 7/D conversion without changing the frequency band of the grid amplifier.

〔Effect of the invention〕

As explained above, this invention reduces the required frequency band of the amplifier and improves temperature resolution by performing horizontal scanning only by six swings of the gimbal without performing horizontal scanning with a scanning mirror when searching for a target. It has the effect of

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing the relationship between gimbal swing and scanning of a two-axis scanning mirror,
FIG. 3 is a diagram showing an embodiment of the preamplifier. In the figure, (3) is a two-axis scanning fttM, v6r is an infrared detector, and (7) is a preamplifier. Agent Masuo Oiwa

Claims (1)

[Claims] (1) A plurality of infrared detection elements are arranged in the vertical direction of the field of view, and an infrared imaging device configured so that horizontal scanning can be performed using a scanning mirror is mounted on a gimbal,
In an infrared homing device that searches for a target by swinging a gimbal horizontally, when searching for a target, scanning is performed only by swinging the gimbal without horizontally scanning the scanning mirror, and when tracking a target, the scanning mirror scans horizontally. An infrared homing device characterized by scanning in a direction. 121 The frequency band of the preamplifier corresponding to each infrared detection element is determined by the presence or absence of horizontal scanning by the scanning mirror.
2. The infrared homing device according to claim 1, characterized in that: