JP2956883B2 - Radio wave reflection type image transmission device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio wave reflection type image transmission device, and more particularly to an image transmission device for wirelessly transmitting an output image of an image pickup device on a moving body to a fixed station by using radio wave reflection.

[0002]

2. Description of the Related Art When working in an area where people are restricted or an area where there is danger to people, a work machine such as a bulldozer or a dump truck is sufficiently provided based on images and images (hereinafter referred to as images) from the work area. May be remotely controlled from a remote control room. One example of remote control is to transmit an output image of an image pickup device attached to a work machine in a work area to an operation room, and to remotely control the work machine in the work area based on the output image. Normally, wireless transmission is used for image transmission by remote control so that the moving range of the work machine is not limited by a wired transmission cable or the like.

Conventionally, in image radio transmission over a relatively long distance such as remote control, an image transmission apparatus using radio waves in a microwave band of, for example, about 50 GHz has been used. However, since this image transmission device uses a high-gain antenna having high directivity, it is necessary to make a transmission antenna and a reception antenna face each other when transmitting an image. Therefore, when image transmission is performed by attaching a transmission antenna to a work machine as in remote control, it is necessary to control the attitude of the transmission antenna according to the movement or turning of the work machine.

Japanese Patent Application No. 6-104199 discloses a satellite navigation system (hereinafter, referred to as GPS) as an example of an image transmission method for controlling the attitude of a transmission antenna attached to a moving body such as a work machine in accordance with the movement of the moving body. An image transmission method using a position measuring device according to the present invention is disclosed. To explain Japanese Patent Application No. 6-104199 to the extent necessary for understanding the present invention with reference to FIG. 5, three-dimensional coordinates of the fixed station 12 are obtained in advance by surveying or the like, and a tertiary coordinate corresponding to the movement of the moving body 1 is obtained. The original coordinates are measured by the GPS position measuring device 6. 3D coordinates of mobile unit 1 and fixed station
From the 12 three-dimensional coordinates, the transmitting directional antenna 5a is a fixed station
The mobile station 1 calculates the transmission azimuth and elevation angle facing the reception directional antenna 15a and directs the transmission directional antenna 5a to the transmission azimuth and elevation angle.
Image transmission to Symbol 5 in the figure is an image transmitter, symbol
Reference numeral 15 denotes an image receiver.

[0005]

However, image transmission involving attitude control of a transmitting antenna has the following problems. (1) It is necessary to perform complicated attitude control for quickly changing the attitude of the transmitting antenna based on a plurality of input signals such as the three-dimensional coordinates and attitude of the moving object. (2) Since the attitude of the relatively heavy transmitting antenna is controlled by following the high-speed movement or turning of the work machine, a large-sized attitude control means having a large driving force is required. (3) There is a possibility that the posture control means, particularly the drive unit thereof, may be damaged by vibration or impact during the operation of the work machine, and the reliability of image transmission is reduced. (4) Since expensive equipment such as a GPS position measuring instrument and complicated control devices are used, the cost for image transmission increases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a radio wave reflection type image transmitting apparatus for transmitting image signals in a plurality of directions while fixing a highly directional transmitting antenna.

[0007]

With reference to the embodiment of FIG. 1, the radio wave reflection type image transmitting apparatus of the present invention transmits an output image of an image pickup device 3 on a moving body 1 to a fixed station 12. , A directional antenna 5a for transmitting an output image of the image pickup device 3 attached to the moving body 1 so as to be vertical when the moving body 1 is in a horizontal posture, and a bottom cone 17 (see FIG. 2) having a convex polygonal shape. A reflector 8 having each side surface as a radio wave reflecting surface 9 and an axis from a bottom surface 17 of the reflector 8 to an apex 18 (see FIG. 2) are directional antennas.
There is provided holding means 10 for holding the reflector 9 on the moving body 1 so as to face the directional antenna 5a along the transmission direction of 5a, and reflects the radio wave incident on the radio wave reflecting surface 9 from the directional antenna 5a in a plurality of directions. It is.

Preferably, as shown in FIG. 2, the bottom surface 17 of the reflector 8 is a regular polygon, and the height of the reflector 8 is the radius of the inscribed circle of the regular polygon. Is reflected in the direction perpendicular to the axis of the reflector 8.

[0009]

The directional antenna 5a used in the present invention is, for example, 50
It can be an antenna having strong directivity for transmitting radio waves of about GHz, which belongs to the related art. Such a radio wave has a property close to light, and is specularly reflected by collision with the radio wave reflection surface 9. If this property is used, a directional antenna
The direction of the radio wave transmitted in a fixed direction from 5a can be changed.

According to the present invention, a plurality of radio wave reflecting surfaces 9 having different normal directions are provided so as to face the directional antenna 5a, and radio waves of a fixed direction transmitted by the directional antenna 5a are made incident on the plurality of radio wave reflecting surfaces 9. The reflector 8a in FIG. 2 is an example of the reflector 8 having a plurality of radio wave reflecting surfaces 9 on the side of the right pyramid. Since the bottom surface 17 of the right pyramid is a convex polygon, the normal directions of the radio wave reflecting surfaces 9 are different from each other. The radio wave from the directional antenna 5a is incident on each radio wave reflection surface 9 by making the vertex of the reflector 8a face the directional antenna 5a and making the axis of the reflector 8a along the transmission direction of the directional antenna 5a. The incident radio wave is reflected in a direction corresponding to the normal direction of the radio wave reflection surface 9, so that a plurality of radio wave reflection surfaces 9 having different normal directions can reflect a radio wave in a fixed direction in a plurality of directions. However, the shape of the right pyramid is not limited to that shown in FIG. 2, and the number and height of the sides of the bottom surface of the reflector 8 can be adjusted according to the directivity of the directional antenna 5a, the position of the fixed station 12, and the like. it can. The material of the reflector 8 may be steel, aluminum, or another material having a high radio wave reflectance.

As shown in FIG. 1, the directional antenna 5a is mounted on the moving body 1 so that the directional antenna 5a faces vertically upward when the moving body 1 on the ground is in a horizontal posture. By holding the pointing axis toward the directional antenna 5a along the transmission direction of the directional antenna 5a, the radio waves of the directional antenna 5a can be transmitted from the mobile unit 1 in a plurality of directions. Although the azimuth of the fixed station 12 viewed from the moving body 1 changes due to the movement or turning of the moving body 1, interruption of radio wave reception at the fixed station 12 can be greatly suppressed by transmitting radio waves to a plurality of directions. In this case, the transmission distance of the directional antenna 5a can be appropriately selected according to the distance between the mobile unit 1 and the fixed station 12 and the reduction ratio of the power of the radio wave due to the reflection of the radio wave reflecting surface 9. Note that the mounting direction of the directional antenna 5a is only required to be vertical, and is not limited to the vertically upward direction shown in FIG.

Thus, the object of the present invention, that is, the provision of "a radio wave reflection type image transmitting apparatus for transmitting image signals in a plurality of directions with a transmitting antenna having high directivity fixed" can be achieved.

Preferably, as shown in FIG. 2, the bottom surface 17 of the reflector 8 is a regular polygon which is a regular dodecagon in this case, and the height of the reflector 8 is a radius of an inscribed circle of the regular polygon. Thereby, the intersection angle between each radio wave reflecting surface 9 and the axis of the reflector 8 is set to 45 °. The radio wave incident substantially parallel to the axis of the reflector 8 is
The light is reflected in a direction perpendicular to the axis by the radio wave reflecting surface 9 which intersects the axis at 45 °. By using the reflector 8 shown in FIG. 2, the radio wave transmitted vertically upward from the directional antenna 5a can be reflected in the horizontal direction as shown in FIG.

More preferably, the number of sides of the bottom surface of the reflector 8 is increased, and the number of directions in which the radio wave is reflected is increased. FIG. 3 shows a reflector 8b in which the side surface of the right cone is replaced by a radio wave reflecting surface 9 instead of the right cone having a convex polygonal bottom. The use of the reflector 8b of FIG. 3 makes it possible to reflect the radio wave transmitted vertically upward from the directional antenna 5a in all directions in the horizontal direction as shown in FIG. As long as the elevation angle of the fixed station 12 is within a certain range, continuous reception of images at the fixed station 12 can be expected.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the use of the reflector 8 having a right-sided cone or a right-sided cone having a convex polygonal bottom as a radio wave reflecting surface 9 allows the radio waves of the directional antenna 5a to be directed to a plurality of directions. It becomes possible to transmit. However, since the elevation angle of the fixed station 12 as viewed from the mobile unit 1 changes in accordance with the change in the height direction and the change in the inclination of the mobile unit 1, in order for the fixed station 12 to continuously receive radio waves, the fixed station 12 is required. It is necessary to reflect a radio wave at an elevation angle that can be received by the receiving directional antenna 15a. In the work of the mobile unit 1 by ordinary remote control, the fixed station 12 viewed from the mobile unit 1
Since the change in the elevation angle is about 30 °, the fixed station 12 can continuously receive a high quality image to a certain extent by using the directional antenna 5a having a half width corresponding to the change in the elevation angle. However, when the FWHM of the directional antenna 5a is smaller than this,
There is a possibility that the radio wave does not reach the fixed station 12 due to a change in the inclination of the image data and the image transmission is interrupted.

FIG. 4 shows a reflector 8c having a hemispherical spherical surface as a radio wave reflecting surface 9a. Reference numeral 17a in the figure represents a circular bottom surface of the hemisphere, and reference numeral 18 represents a vertex of the hemisphere intersecting a vertical line set at the center of the circular bottom surface 17a. For example, the axis extending from the center of the circular bottom surface 17a to the vertex 18 by the holding means 10 is
The reflector 8c is held so as to face the directional antenna 5a along the transmission direction of a. The directivity of the radio wave reflected by the spherical radio wave reflecting surface 9a is weaker than that of the radio wave reflected by the radio wave reflecting surface 9 on the side of the right pyramid, so that the above-described interruption of image transmission can be expected to be further suppressed.

The radio wave reflection type image transmitting apparatus mounted on the mobile unit 1 has been described above. Image and other data transmission from the mobile unit 12 to the mobile unit 1 can be performed. Further, by using the image transmitter 5 and the image receiver 15 shown in FIG. 1 as image transmission devices capable of transmitting and receiving, respectively, bidirectional image and other data transmission in FIG. 1 becomes possible.

[0018]

As described in detail above, the radio wave reflection type image transmitting apparatus of the present invention has a directional antenna attached to a mobile body so that the mobile body is vertical when the mobile body is in a horizontal posture, and a convex polygonal bottom surface. A reflector having a radio wave reflecting surface on each side of the right pyramid, and the reflector held by the moving body such that a perpendicular from the bottom surface of the reflector to the vertex is directed to the directional antenna along the transmission direction of the directional antenna. Since a holding means is provided to reflect the radio wave incident from the directional antenna to the radio wave reflecting surface in a plurality of directions, the following remarkable effects are obtained.

(1) While the directional antenna is fixed in a fixed direction, interruption of image transmission to a fixed station within a certain range of elevation as viewed from the mobile body can be greatly suppressed. (2) Since there is no rotating part, there is little possibility that a failure occurs in the image transmission device, and the reliability of image transmission can be improved. (3) Compared with the conventional image transmission from a moving object, expensive sensors and attitude control means are not required, so that a small and inexpensive image transmission device can be obtained. (4) By reducing the directivity of the radio wave reflected by the radio wave reflecting surface as a spherical surface, it is expected that interruption of image transmission can be further suppressed. (5) The present invention can also be applied to bidirectional image transmission between a mobile unit and a fixed station.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of the present invention.

FIG. 2 is an explanatory view showing an example of the reflector of the present invention.

FIG. 3 is an explanatory view showing another example of the reflector of the present invention.

FIG. 4 is an explanatory view showing still another example of the reflector of the present invention.

FIG. 5 is an explanatory diagram showing an example of a conventional technique.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 moving body 2 ground surface 3 image pickup device 5 image transmitter 5a directional antenna for transmission 6 position measuring device 8 reflector 9, 9a radio wave reflection surface 10 holding means 12 fixed station 15 image receiver 15a directional antenna for reception 17 convex Square bottom 17a Circular bottom 18 Vertex.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hirohisa Motohisa 2-9-1-1, Tobita-Ki, Chofu-shi, Tokyo Kashima Construction Co., Ltd. Technical Research Institute (58) Field surveyed (Int.Cl. ⁶ , DB name) H04B 7/24-7/26 102 H04Q 7/00-7/38 H01Q 19/10

Claims (5)

(57) [Claims] 1. An image transmission apparatus for transmitting an output image of an image pickup device on a moving object to a fixed station, wherein the output image of the image pickup device attached to the moving object so as to be vertical when the moving object is in a horizontal posture. A directional antenna for transmission, a reflector whose bottom surface is a radio-wave reflecting surface with each side surface of a right-sided pyramid having a convex polygon, and an axis from the bottom surface of the reflector to the vertex extends along the transmission direction of the directional antenna. A radio wave reflection type image transmission device comprising: holding means for holding the reflector on the moving body so as to face the directional antenna, and reflecting a radio wave incident on the radio wave reflection surface from the directional antenna in a plurality of directions. . 2. The image transmitting apparatus according to claim 1, wherein the bottom surface of the reflector is a regular polygon, and the height of the reflector is a radius of an inscribed circle of the regular polygon, so that the radio wave reflection is achieved. A radio wave reflection type image transmitting apparatus which reflects a radio wave incident on a surface in a direction perpendicular to an axis of the reflector. 3. An image transmitting apparatus according to claim 1, wherein said reflector is a right-sided cone instead of a right-sided cone having a convex polygonal bottom surface, and a side surface of said right-sided cone serves as said radio wave reflecting surface. Reflective image transmission device. 4. An image transmitting apparatus according to claim 1, wherein said reflector is a hemisphere instead of a right-sided pyramid having a convex polygonal bottom surface, and said spherical surface of said hemisphere serves as said radio wave reflection surface. Image transmission device. 5. An image transmitting apparatus according to claim 1, wherein said reflector is made of steel or aluminum.