JPS61219825A - Apparatus for measuring distance between cars - Google Patents

Abstract

PURPOSE:To automatically measure and display the distance between cars, by confirming and extracting the number plate part from the image signal of a television camera and automatically operating and displaying the distance between cars from the time width of the number plate on a scanning line. CONSTITUTION:One frame or one field of the image signal of the succeeding car 20 outputted from the television camera 1 mounted to a car 10 is accumulated in an image memory 2 and a pattern confirmation circuit 3 confirms and extracts a number plate part from the output signal of the image memory 2 to output the time width on a scanning line corresponding to the lateral width of the number plate parts of the image signal to an operation circuit 4. An image mixer circuit 6 synthesized the output signal of a display signal generation circuit 5 and that of the television camera 1 and superposes the distance L between cars to the image of the succeeding car 20 to display the same on the monitor picture of a display apparatus 7.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an inter-vehicle distance measuring device for measuring and displaying an inter-vehicle distance between automobiles.

SUMMARY OF THE INVENTION The present invention provides an inter-vehicle distance measuring device that photographs an automobile with a television camera and measures an inter-vehicle distance from the video signal, which includes: extracting the license plate portion of the automobile from the output signal of the television camera using a pattern recognition circuit; The inter-vehicle distance is calculated and output from the output of the pattern recognition circuit.

Prior Art A conventional device of this kind simply displays an image including the license plate portion of a car on a television screen, and uses a scale in which a distance scale as shown in Fig. 6 is written on the image of the license plate displayed on the television screen. The approximate distance is measured by overlapping the two.

The conventional inter-vehicle distance measuring device described above is complicated and difficult to measure accurately, and it is extremely difficult to instantly judge the distance while driving. Furthermore, if you are not looking at the TV monitor, you cannot ensure your safety, and there is also the disadvantage that your attention is divided while driving.

Problems to be Solved by the Invention The present invention solves the above-mentioned conventional drawbacks and provides an inter-vehicle distance measuring device that automatically calculates and outputs an inter-vehicle distance from a video signal of a television camera.

Means for Solving the Problems The inter-vehicle distance measuring device of the present invention includes a television camera, a pattern recognition circuit for extracting a license plate portion from a video signal of a car outputted from the television camera, and an output from the pattern recognition circuit. The vehicle is characterized by comprising an arithmetic circuit that calculates an inter-vehicle distance and a display circuit that displays the output of the arithmetic circuit.

Embodiments of the Invention Next, the present invention will be described in detail with reference to the drawings.

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

That is, one frame or field of the video signal of the following vehicle output from the television camera mounted on the vehicle is stored in the image memory 2, and the pattern recognition circuit 3 recognizes the license plate portion from the output signal of the image memory 2. , and outputs the time @W (x seconds) on the scanning line corresponding to the width of the license plate portion of the video signal to the arithmetic circuit 4. The arithmetic circuit 4 calculates and outputs the inter-vehicle distance from the time width W using the following formula.

L=L, W, /W ・・・・・・・・・・・・・・・
...... (1) However, Wo is the time width on the scanning line of the license plate when the following distance is 1, and is a predetermined value. Since the width of the license plate is constant for all cars, it is possible to measure the inter-vehicle distance using equation (1). The output of the arithmetic circuit 4 is sent to a display signal generation circuit 5 and converted into a signal in an arbitrary display format. The video mixing circuit 6 combines the output signal of the display signal generating circuit 5 and the output signal of the television camera 1, superimposes the inter-vehicle distance on the video of the following vehicle, and displays the superimposed image on the monitor screen of the display device 7.

FIG. 2 is a diagram showing the relationship between the automobile 10 equipped with the television camera I and the following vehicle 20, and the inter-vehicle distance is L. In this case, the video signal output from the television camera l is
As shown in FIG. 3, it includes the entire view of the following vehicle. FIG. 4 is an image of the license plate portion recognized and extracted by the pattern recognition circuit 3, and the arithmetic circuit 4 calculates that the inter-vehicle distance is, for example, 20M based on the time width W on the scanning line.

The display signal generation circuit 5 outputs the calculation result of the calculation circuit 4 as a video signal in an arbitrary display format, and combines this signal with the output signal of the television camera l in the video mixing circuit 6 to output the result to the display device 7.
input. FIG. 5 is a diagram showing an example of the monitor screen of the display device 7. As shown in FIG. The inter-vehicle distance can be displayed in any format, such as a graphic display, instead of a numerical display. Further, when the distance between vehicles becomes dangerous, it is easy to flash the display signal, display an alarm, or issue a warning by voice. In addition, the display of the following distance,
It is also possible to employ any display means other than a video monitor, such as a meter display or a graphic display using a liquid crystal.

Effects of the Invention As described above, the present invention is configured to recognize and extract the license plate portion from the video signal of the television camera, and automatically calculate and display the inter-vehicle distance from the time width of the license plate on the scanning line. This has the effect of automatically measuring and displaying the distance between vehicles. It greatly contributes to safe driving of cars.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. Figure 2 is a diagram showing the relationship between a car equipped with a TV camera and a following vehicle, Figure 3 is a diagram showing an example of the video signal of the TV camera, and Figure 4 is a license plate pattern recognized and extracted from the video signal. FIG. 5 is a diagram showing an example of a monitor screen of a display device, and FIG. 6 is a diagram showing an example of a conventional scale for measuring inter-vehicle distance. In the figure, 1: TV camera, 2: Image memory, 3:
Pattern recognition circuit, 4: Arithmetic circuit, 5: Display signal generation circuit, 6: Video mixing circuit, 7: Display device, 1O: Car equipped with a television camera, 2o: Following vehicle.

Claims (1)

[Claims] A television camera, a pattern recognition circuit that extracts a license plate part from a video signal of a car output from the television camera, an arithmetic circuit that calculates an inter-vehicle distance from the output of the pattern recognition circuit, and an output of the arithmetic circuit that displays the output of the arithmetic circuit. An inter-vehicle distance measuring device characterized by comprising a display circuit for.