JPH09138282A - Radar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a radar whose directional resolution is enhanced without making the cell of a reception means fine. SOLUTION: In a radar, a transmission means which transmits a beam so as to be spread, a condensing lens 4 as a means to receive reflected waves of the beam reflected by a target and a plurality of photodiode arrays 5 are installed. The respective photodiode arrays 5 are arranged in an array shape in such a way that their directions are different. The direction of the target is obtained on the basis of the position of every received photodiode array 5. A distance up to the target is measured on the basis of the time which elapses until the reflected waves are received since the beam is transmitted. In this case, the photodiode arrays 5 are situated in positions which are different from the focal position of the condensing lens 4 so as to be set to an out-of-focus state, and the size of a spot due to the state is constituted to be larger than every size of the photodiode arrays 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar in which directional resolution is improved by devising a target direction as an analog amount.

[0002]

2. Description of the Related Art As a conventional radar, for example, there is one shown in FIG. The figure shows a radar disclosed in Japanese Patent Application No. 6-243381. Explaining the configuration, a light emitting diode (LED) 2 as a sending unit controlled by the signal processing device 1 emits light in response to a command from the signal processing device 1 and emits light such as visible light or infrared light or an electromagnetic wave pulse. . The light reflected by the target 3 reaches a photodiode array (receiving means) 5 through a condenser lens (condensing means) 4. The output of the photodiode array 5 is connected to the signal processing device 1 via the scanning switch array 6. The scanning of the scanning switch array 6 is controlled by the signal processing device 1.

Here, the photodiode array 5 is aligned with the focal point of the condenser lens 4 similarly to a general light receiving element. Then, as shown in the drawing, the reflected light from the target 3 in various directions is refracted by the condenser lens 4 and condensed on one point smaller than one photodiode cell on the photodiode array 5. Since the focal point, that is, the image of the target is on the line connecting the centers of the target 3 and the condenser lens 4, the direction θ of the target 3 can be calculated by detecting its position. The position of the focal point can be examined by scanning the scanning switch array 6. Thus, the radar shown in FIG.
The feature is that the distance to the target and the direction of the target can be detected at the same time.

The solid line in FIG. 4 shows the relationship between the direction detected using the conventional radar configuration of FIG. 5 and the actual target direction. Since the reflected light reaching the same light receiving cell has the same output, the output direction has discrete digital values as shown in the figure. Therefore, in order to improve the directional resolution, it is necessary to miniaturize the light receiving cell.

[0005]

However, such a conventional radar requires miniaturization in order to increase the directional resolution, and there is a technical and economical limit to miniaturization. Therefore, there is a problem that the directional resolution is limited and cannot be sufficiently improved.

The present invention has been made by paying attention to such a conventional problem, and the photodiode array 5 is placed at a position other than the focus position to create a defocused state and detect the center of gravity of the blur. Therefore, it is intended to solve the above problems.

[0007]

Means for Solving the Problems In order to achieve the above-described object, the present invention provides a delivery means for delivering a beam of an electromagnetic wave or the like, the delivered beam having a predetermined spread, and the delivered beam as a target. A receiving means for collecting the reflected waves as a means for receiving the reflected waves and a plurality of receiving means are provided, and the receiving means are arranged in an array so that their directions are different from each other, and received signals are received. In a radar that obtains the direction of the target based on the position of the means, and measures the distance to the target from the time from the transmission of the beam to the reception of the reflected wave, the pointing directions of the plurality of receiving means intersect. The receiving means is placed in a defocused state at a position different from the focus position of the condensing means, and the size of the spot due to the blurring is larger than each size of the plurality of receiving means. Was. In the invention according to claim 2, the receiving means is placed closer to the light collecting means than the focus of the light collecting means.

[0008]

Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an embodiment of the invention. The configuration is the same as the conventional example shown in FIG. 5 disclosed in Japanese Patent Application No. 6-243381, but here, the photodiode array 5 is aligned not at the focus position f but at a position y shorter than that. ing. Further, although not shown in the figure, it has means for scanning the output of each cell of the photodiode array 5 and calculating the center of gravity thereof.

Next, the operation will be described. As shown in FIG. 1, the reflected light in various directions is refracted by the lens 4 and tries to be condensed at one point, but it cannot be condensed and reaches many cells of the photodiode array 5, causing blurring. At this time, the center of gravity of the blur is on the line connecting the center of the condenser lens 4 and the target, and corresponds to the direction θ. When the output intensity on the axis X as shown in the figure is written as a function of X, it becomes as shown in FIG. FIG.
The center of gravity of the blur, that is, θ can be calculated by calculating the center of gravity X _O of the output intensity. In this case, θ does not take discrete values, but becomes a continuous analog quantity as shown by the dotted line in FIG. Therefore, the directional resolution can be improved without depending on the miniaturization.

In FIG. 1, y is made shorter than the focus position f in order to make the image out of focus, but y is made longer than the focus position f and the focus is out of focus, so that the effect described above can be obtained. However, y
When is longer than the focal position f, the angle of view becomes smaller. Therefore, when y is shorter than the focal position f, the angle of view can be increased in the same light receiving window.

Up to this point, the description has been made so that the photodiode array 5 is scanned, but Japanese Patent Application No. 6-24.
The direction can be detected using the same principle as PSD without scanning the photodiode array 5 as disclosed in 3381. Even in that case, the present invention can be applied and PS
Since the output of D becomes the center of gravity of the output of each cell, it is not necessary to prepare a means for calculating the center of gravity.

FIG. 3 shows another embodiment. When an electromagnetic wave other than light such as a millimeter wave is used, a concave mirror 7 is used instead of a lens as a light collecting means. Even in this case, the photodiode array 5 is also similar to the above description.
Bokeh can be introduced by setting the position other than the focus position f, and the direction of the target can be calculated as an analog amount by calculating the center of gravity of the blur.

[0013]

As described above, according to the present invention, by placing the receiving array for receiving the reflected wave in a position other than the focal point of the light condensing means, a defocused state is created and the center of gravity of the blur is changed. Since the direction of the target is calculated, the direction can be calculated as an analog amount, and as a result, the direction resolution can be improved without depending on miniaturization.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an embodiment of the present invention.

FIG. 3 is a diagram showing another embodiment of the present invention.

FIG. 4 is a diagram showing a directional relationship between a direction detected by the conventional radar and the radar of the embodiment and an actual target direction.

FIG. 5 is a diagram showing a conventional radar.

[Explanation of symbols]

 1 Signal Processing Device 2 Light Emitting Diode (Transmitting Means) 3 Target 4 Condensing Lens (Condensing Means) 5 Photodiode Array (Receiving Means) 6 Scanning Switch Array 7 Concave Mirror (Condensing Means)

Claims (2)

[Claims] 1. A transmission means for transmitting a beam such as an electromagnetic wave, the transmitted beam having a predetermined spread, and a reflected wave as a means for receiving the reflected wave reflected from the target by the transmitted beam. Light collecting means and a plurality of receiving means are provided, and the receiving means are arranged in an array so that the directions thereof are different, and the direction of the target is obtained based on the position of the received receiving means, and the beam In the radar that measures the distance from the time from the transmission of the reflected wave to the target, the receiving means is placed at a position different from the focus position of the converging means in which the directions of the plurality of receiving means intersect, A radar, which is in a defocused state, wherein a size of a spot caused by the blur is larger than each size of the plurality of receiving means. 2. The radar according to claim 1, wherein the receiving means is placed closer to the light collecting means than the focus of the light collecting means.