JPH06331725A - Millimetric wave image pickup system - Google Patents

Abstract

PURPOSE:To shorten the image producing time while realizing acquisition of highly accurate view image. CONSTITUTION:A receiving array 11 comprises a combination of a plurality of antenna elements corresponding, in number, with pixels for forming an image on the local plane of an antenna reflector 10. Millimetric wave signals received by the plurality of antenna elements of the receiving array 11 are detected to produce image signals for respective pixels. The image signals are then subjected to scanning conversion to produce image signals for one screen which are presented on a CRT display section 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a millimeter wave image pickup device suitable for use in, for example, a tracking device.

[0002]

2. Description of the Related Art In general, an image pickup device for picking up a desired field of view in space has its beam width (for example, beam width θ of a circular aperture antenna: used wavelength λ, aperture diameter D, and the radial power gain point of the antenna). Beam width θ: about 1.2 × (λ /
It is said that it is advantageous for an image to make D) rad) as small as possible. In such an image pickup device, since the aperture diameter D of the antenna is constant, it is necessary to reduce the wavelength λ used as much as possible. As a minimum wavelength range of such a used wavelength λ, there is a millimeter wave signal in a wavelength range having a good atmospheric transmissivity in the 94 GHz band (λ is about 3 mm).

Therefore, in a millimeter wave image pickup device for picking up such a millimeter wave image and converting it into an image, for example, FIG.
As shown in FIG. 2, a method of mechanically scanning the antenna reflecting mirror 1 in the horizontal and vertical directions with beam width accuracy and receiving a millimeter wave signal from the field of view of the space to generate a millimeter wave image is considered. .

However, in the above-mentioned millimeter wave image pickup device, for example, in a space of 20 ° in the horizontal direction and 10 ° in the vertical direction, a millimeter wave having a wavelength of 95 GHz band (λ = 3.16 mm) has a diameter D = 20 cm. When scanning with the beam width of the antenna reflector 1 having the aperture of about 1 degree, 20 × 10 = 20
Reception is required 0 times or more (about 400 times or more if the beam radius is overlapped and scanned). Therefore, for example, if one reception time is 10 ms in consideration of the improvement of the S / N ratio, a scene in one space is imaged in a time of about 2 seconds to 4 seconds or more, and one image is displayed. It has a problem of spending a long time.

Further, as such a millimeter-wave image pickup device, it is conceivable that an electronic scanning antenna is used to electronically scan the beam, but in this case also, the antenna reflection is performed mechanically. Similar to scanning a mirror, it takes a lot of time to image a scene in one space, and there is a problem that it takes a long time to display one image.

[0006]

As described above, the conventional millimeter wave image pickup device has a problem that it takes a long time to display an image. The present invention has been made in view of the above circumstances, and a millimeter wave image having a simple structure and capable of realizing highly accurate visual field image acquisition and shortening the visual field image output time. An object is to provide an imaging device.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to an antenna reflecting mirror which is arranged so as to face a target direction and receives a millimeter wave signal from the target direction, and the antenna reflecting mirror which is arranged so as to face the focal plane of the antenna reflecting mirror. A plurality of antenna elements that receive the millimeter-wave signals reflected by the reflecting mirror are arranged in a combination corresponding to the number of pixels forming an image, and the millimeter-wave signals received by the plurality of antenna elements are respectively detected to detect each pixel. A millimeter wave receiving unit that generates an image signal and a display unit that scan-converts the image signal obtained by the millimeter wave receiving unit to generate an image signal for one image and displays a millimeter wave image are provided. The image pickup device is configured.

[0008]

According to the above construction, when the antenna reflecting mirror is arranged toward a desired target direction in space, a millimeter wave signal from the target direction is reflected by the antenna reflecting mirror and a plurality of antenna elements of the millimeter wave receiving means. , Each of which is detected to generate an image signal for each pixel, and the charge for each pixel is scan-converted to be converted into an image signal for one image and displayed as a millimeter wave image. As a result, it is possible to acquire a millimeter wave image in the visual field direction without performing the reflection mirror scanning in the visual field direction or the electron beam scanning, and it is possible to perform a quick and highly accurate display.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a millimeter wave image pickup device according to an embodiment of the present invention. In FIG. 1, reference numeral 10 denotes an antenna reflector, which is composed of, for example, a parabolic antenna or a Cassegrain antenna. On the focal plane F of the antenna reflector 10, the receiving array 11 is provided on the supporting member 1 as shown in FIG.
The two are arranged opposite to each other. In this reception array 11, for example, as shown in FIG. 3, when n × m corresponds to the number of pixels of an image, and the distance d is the focal plane of the antenna reflecting mirror 11 is F and the used wavelength is λ, the distance d ≧ 2.4 × F × λ are combined and arranged. Here, the focal plane F of the antenna reflecting mirror is represented by F = D / f, where D is the diameter of the antenna reflecting mirror and f is the focal length of the antenna reflecting mirror.

For example, the reception array 11 is formed by laminating a Ga As substrate 11a and a Si substrate 11b as shown in FIG. 4, of which the Ga As substrate 11a is provided with an antenna element 11c. Corresponding to, low noise amplifier (LNA) 11d HEMT (High
The Schottky diode 11e is formed by an Eiectron Mobility Transistor and has a MMIC (Monolith).
c Microwave Integrated Circuit) technology. On the other hand, the Si substrate 11b has an M switch as an input switch.
The OS switch 11f, the MOS capacitor C, and the MOS switch 11g are formed in a MOS structure, and the horizontal transfer CCD 11h is formed. And these Ga
The As substrate 11a and the Si substrate 11b have mutual electrodes 11
The space between i and 11j is a metal 11k, such as indium (I
m) is pressed and joined.

As shown in FIG. 1, the reception array 11 has a signal input terminal to which a reception array drive circuit 13 is connected, and an output terminal to which an analog / digital (A / D) signal is supplied.
The conversion circuit 14 is connected. Then, the reception array 11
Is a receiving array drive circuit 1 connected to its signal input terminal
The image signal for each pixel is output to the A / D conversion circuit 14 on the basis of the read clock from 3. A / D conversion circuit 14
The scan conversion unit 15 is connected to the output terminal thereof, and the input image signal is A / D converted based on the conversion clock from the reception array drive circuit 13 and output to the scan conversion unit 15. A CRT display unit 16 is connected to the scan conversion unit 15,
The image signal from the A / D conversion circuit 14 is scan-converted based on the timing signal from the reception array drive circuit 13 to obtain 1
The image signals are converted into image signals and output to the CRT display unit 16.

In the above structure, the antenna reflector 10
Are arranged facing each other in the target direction, the millimeter wave signal from the target direction is applied to the mirror surface. The millimeter wave signal reflected by the antenna reflector 10 is received by the receiving array 1 as shown in FIG.
The antenna element 11c of 1 receives. At this time, in the reception array 11, when the gate of the MOS switch 11f is opened, the millimeter wave signal guided to the antenna element 11c is LNA.
The signal is amplified by 11d, converted into a detection current by the Schottky diode 11e, and the image signal is stored in the MOS capacitor C. Then, when the gate of the MOS switch 11f is closed and the gate of the MOS switch 11g is opened,
The image signal stored in the MOS capacitor C is the CCD 11
It is output to the A / D conversion unit 14 via h.

The A / D converter 14 includes an antenna element 11
The image signals corresponding to the n × m horizontal and vertical pixels received in c are input in time series, and the input / output image signals corresponding to the m × n pixels are A / D-converted to perform a scan conversion unit. 15
Output to. The scan conversion unit 15 scan-converts the image signal from the A / D conversion circuit 14 based on the timing signal from the reception array drive circuit 13 to convert it into an image signal for one image, and outputs it to the CRT display unit 16. . Here, the CRT display unit 16 displays a millimeter wave image of a desired visual field centered on the target direction based on the image signal.

As described above, the millimeter wave image pickup device is
The reception array 11 in which a plurality of antenna elements 11c are arranged in combination corresponding to the number of pixels forming an image is arranged on the focal plane of the antenna reflector 10, and the reception array 11 receives the plurality of antenna elements 11c. The millimeter wave signal is detected to generate an image signal for each pixel, and the image signal is scan-converted to acquire an image signal for one image and display the image signal on the CRT display unit 16. According to this, it is possible to acquire a millimeter wave image in the target direction only by arranging the antenna reflecting mirror 10 toward a desired target direction in the space, and thus it is possible to perform reflection mirror scanning in the visual field direction as in the conventional case. Since the electron beam scanning is not performed, the blind associated with the scanning is effectively prevented, and the millimeter wave image can be displayed quickly and with high accuracy. That is, in image processing, the reception gate time can be performed at a speed of (1/60) sec / 1 frame or more, which is 1
Since the output speed of one millimeter-wave image is increased, it is suitable to be applied to a precision tracking system mounted on a flying object, for example.

Further, according to this, since the conventional scanning mechanism for scanning the antenna reflecting mirror 1 is not required, the reliability of the image to be acquired is improved and at the same time,
Since the size and weight can be promoted and the receiving array 11 can be formed by using the semiconductor technology, it has the advantages of mass production and simplification of manufacturing.

Although the above embodiment has been described in the case of being applied to a passive receiving system for receiving a millimeter wave signal emitted from a target direction, the present invention is not limited to this, and for example, a millimeter wave signal is emitted in the target direction. It can also be applied to an active reception system in which a millimeter wave signal reflected by a target is received. Therefore, the present invention is not limited to the above embodiment,
Of course, various modifications can be made without departing from the scope of the present invention.

[0017]

As described in detail above, according to the present invention, it is possible to realize a highly accurate acquisition of a visual field image with a simple structure and to shorten the output time of the visual field image. It is possible to provide the millimeter wave image pickup device.

[Brief description of drawings]

FIG. 1 is a diagram showing a millimeter wave image pickup device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an arrangement state of an antenna reflector and a receiving array of FIG.

FIG. 3 is a diagram showing an arrangement example of antenna elements of the reception array in FIG.

FIG. 4 is a diagram showing a part of details of the reception array shown in FIG.

FIG. 5 is a diagram shown for explaining the operation of the reception array of FIG.

FIG. 6 is a diagram shown for explaining a conventional problem.

[Explanation of symbols]

 10 ... Antenna reflector. 11 ... Reception array. 11a ... GaAs substrate. 11b ... Si substrate. 11c ... Antenna element. 11d ... LNA. 11e ... Schottky diode. 11f, 11g ... MOS switches. C ... MOS capacitor. 11h ... CCD. 12 ... Support member. 13 ... Receiving array drive circuit. 14 ... A / D conversion circuit. 15 ... Scan converter. 16 ... CRT display section.

Claims (1)

[Claims] 1. An antenna reflecting mirror which is arranged opposite to a target direction and receives a millimeter wave signal from the target direction, and a millimeter wave signal which is arranged opposite to a focal plane of the antenna reflecting mirror and is reflected by the antenna reflecting mirror. A plurality of antenna elements for receiving the signals are arranged in combination corresponding to the number of pixels forming the image, and millimeter wave signals are generated by detecting the millimeter wave signals received by the plurality of antenna elements. A millimeter wave image pickup device comprising: a means and a display means for scanning and converting the image signal obtained by the millimeter wave input signal receiving means to generate an image signal for one image and displaying the millimeter wave image.