JPH11296786A - Vehicle number recognition device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To recognize a license plate number of a vehicle efficiently without performing useless recognition processing. SOLUTION: Loop coils 22a to 22g are buried before a gate 21 at an entrance of a parking lot, and sensors 23a to 23g are connected to the loop coils 22a to 22g. The control computer 24 includes the sensors 23a to 23
g, the cameras 26a to 26
e, a camera having a high probability that the license plate 20a of the vehicle 20 is reflected is determined, an image signal from the camera is taken in through the camera selection switch box 25, the image signal is processed, and the license plate 20a is processed. Recognize numbers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle number recognizing device for recognizing the number of a license plate of a vehicle, for example, for managing parking in a parking lot.

[0002]

2. Description of the Related Art Conventionally, in order to perform parking management of a parking lot,
In some cases, the number of the license plate of the vehicle is recognized at the entrance. FIG. 9 shows the configuration of the recognition device. In front of the gate 11 at the entrance of the parking lot, a loop coil 12 is buried, and when the driver of the vehicle 10 stops the vehicle 10 in front of the gate 11 to take a parking ticket from a ticketing machine (not shown), Loop coil 12
And the sensor 13 detects the vehicle.

In response to the detection of the vehicle, the control computer 14 sends a first signal via the camera selection switch box 15.
An image signal is captured from the camera 16a, and the image signal is processed to recognize the number of the license plate 10a of the vehicle, and the recognized number is transmitted to the management computer 17. The management computer 17 stores the recognition number and the storage time in a database to perform storage management, and also opens and closes the gate 11 to put the vehicle 10 in the parking lot.

If the number captured cannot be recognized in the image captured by the first camera 16a due to, for example, a different stop position of the vehicle, the control computer 14 sets the first computer 16a to the first position.
Camera 16b having a different shooting range from camera 16a
And performs a number recognition process.
When the number cannot be recognized even by the image signal from the second camera 16b, the control computer 1
4 transmits the message to the management computer 17 and displays a message on the display of the management computer 17. By this message display, the manager reads the number from the image of the front of the vehicle displayed on the monitor 18 and stores the number in the management computer 17.
, So that the warehouse management and the opening and closing of the gate 11 can be performed.

[0005]

In the above-mentioned apparatus, since a camera having a wide angle of view in the width direction of the area where the vehicle passes at the entrance of the parking lot is used, the area occupied by the license plate in the entire image is used. However, there is a problem that the number recognition rate is low. In order to solve this problem, it is conceivable to use a camera having a narrow angle of view and use a larger number of cameras than two conventional cameras to recognize numbers.

However, in this case, if an image signal from a camera is taken in according to a predetermined priority as in the above-described conventional one, for example, when a license plate is reflected on a camera having a low priority,
Unnecessary recognition processing must be performed before the user gets there, and there is a problem that recognition time is required. The present invention has been made in view of the above problem, and has as its object to enable efficient number recognition processing without performing useless recognition processing.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, a position of a vehicle in a width direction of a traversable area of the vehicle is detected, and an image is captured based on the detection. The photographing means to be determined is determined, and the number of the license plate of the vehicle is recognized based on the image captured by the photographing means.

As described above, since the image of the position where the vehicle is present is taken in and the number of the license plate is recognized, the number recognition processing can be efficiently performed without performing useless recognition processing. The invention according to claim 2 is characterized in that a plurality of photographing means are installed on the gate. In this case, a dedicated space for mounting a plurality of photographing means can be eliminated.

According to the present invention, the position of the vehicle in the width direction of the traversable area of the vehicle is detected,
The photographing direction of the photographing means is changed based on the detection, and the number of the license plate of the vehicle is recognized based on an image captured by the photographing means after the change. According to the present invention, the same effect can be obtained by reducing the number of photographing means as compared with the first aspect.

According to the present invention, the position of the vehicle in the width direction of the traversable area of the vehicle is detected,
It is characterized in that the license plate number of the vehicle is recognized based on the image of the detected position. Also in the present invention, the number recognition processing can be performed efficiently. In this case, the position of the vehicle is detected one-dimensionally in the width direction of the traversable area of the vehicle as in the invention described in claim 5, or as in the invention described in claim 6. Detection can be performed two-dimensionally in the possible area.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 shows a configuration of a first embodiment in which the present invention is applied to a system for managing parking in a parking lot. In this embodiment, before the gate 21 at the entrance of the parking lot, a loop coil 22a is provided.
22g are embedded, and sensors 23a to 23g are connected to the loop coils 22a to 22g. A vehicle sensor is configured to detect the presence of a vehicle with one loop coil and one sensor, and a plurality of such vehicle sensors are installed in a width direction of a traversable area at an entrance of a parking lot, so that the vehicle exists. The position at which it is performed can be detected one-dimensionally.

FIG. 2 shows a specific configuration of one loop coil. This loop coil has a plurality of turns (5
.About.6 turns), and a constant high-frequency current flows from the sensor. When the vehicle passes over the loop coil, the magnetic field is disturbed, and the impedance of the loop coil changes. The sensor processes a frequency change due to a change in the impedance of the loop coil, and outputs a vehicle detection signal.

On the ceiling behind the gate 21, a plurality of cameras 26a to 26e are arranged one-dimensionally. Each of the cameras 26a to 26e has a smaller angle of view than the conventional one shown in FIG. 9, and can capture images in mutually different ranges in the width direction of the traversable area. Note that, as shown in the drawing, the photographing ranges of the adjacent cameras overlap each other.

The control computer 24 has sensors 23a to 23a.
A camera having a high probability that the license plate 20a of the vehicle 20 is reflected is determined based on a signal from the camera 23g, and an image signal from the camera is transmitted to the camera selection switch box 2.
5 and processes the image signal to obtain the vehicle 20
The number of the license plate 20a is recognized, and the recognized number is transmitted to the management computer 27.

The management computer 27 stores the recognition number and the storage time in a database to perform storage management, and also opens and closes the gate 21 to put the vehicle 20 in the parking lot. If the number cannot be recognized, the control computer 24 transmits the information to the management computer 27 and causes the display of the management computer 27 to display a message to that effect. By this message display, the manager reads the number from the image of the front part of the vehicle displayed on the monitor 28 and inputs the number to the management computer 27 so that the warehouse management and the opening and closing of the gate 21 can be performed.

Next, the operation of the above will be described with reference to the flowchart of FIG. The control computer 24 includes a sensor 23a
It is determined whether or not any of the sensors has output a vehicle detection signal based on the signals from 〜23g (step 101).

When the vehicle 20 stops in front of the gate 21 and a vehicle detection signal is output from any of the sensors, the control computer 24 generates a first candidate for capturing an image signal based on the vehicle detection signal. And a second candidate camera are determined (step 102). Specifically, the correspondence between the sensor that outputs the vehicle detection signal and the camera as the first and second candidates is stored in advance as a map, and the first and second candidate cameras are determined using the map. I do. At this time, if the number of the sensors from which the vehicle detection signal is output is an odd number, the first and second cameras are sequentially arranged in order from the camera which captures the center loop coil among the loop coils corresponding to those sensors in the widest range. Set candidates. When the number of sensors from which the vehicle detection signal is output is an even number, the first and second cameras are arranged in order from the camera that captures the center two loop coils in the widest range among the loop coils corresponding to those sensors. Set two candidates.

The control computer 24 controls the camera selection switch box 25 to fetch an image signal from the first candidate camera, processes the image signal, and performs processing for recognizing the number of the license plate 20a of the vehicle 20. (Step 103). Then, it is determined whether or not the number has been recognized by the recognition processing (step 10).
4) When the number is recognized, the recognized number is transmitted to the management computer 27 (step 1).
05). As a result, the management computer 27 stores the transmitted number and the storage time in the database to perform storage management, and also opens and closes the gate 21 to put the vehicle 20 in the parking lot.

When the control computer 24 determines in step 104 that the number could not be recognized by the image signal from the first candidate camera, it takes in the image signal from the second candidate camera and A recognition process is performed (step 106). Then, when it is determined that the number has been recognized by the recognition process (step 107), the process proceeds to step 105, and the recognized number is transmitted to the management computer 27.

When the control computer 24 determines in step 107 that the number could not be recognized by the image signal from the camera of the second candidate, the control computer 24 transmits to the management computer 27 that the number could not be recognized (step 107). Step 108). At this time, the management computer 2
7 displays a message to that effect on the screen. Then, the manager reads the number from the image of the front part of the vehicle displayed on the monitor 28 and inputs the number to the management computer 27, thereby performing warehousing management and opening and closing the gate 21.

The above-described processing is performed every time a vehicle detection signal is output from any of the sensors. According to the above-described embodiment, the number of cameras 26a to 26e is increased compared to the conventional one shown in FIG. 9 and the angle of view is narrowed, so that the number recognition rate can be increased. In addition, since the loop coils 22a to 22g are installed in the width direction of the vehicle traversable area and the position of the vehicle in the width direction is detected to determine a camera having a high probability that the license plate is reflected, there is no waste. Recognition processing time can be shortened without performing complicated recognition processing. (Second Embodiment) In the first embodiment, the cameras 26a to 26e are installed at the ceiling position of the parking lot. However, as shown in FIG.
a to 26e may be installed. By installing the cameras 26a to 26e using the gate 21 in this way, the place and time required for mounting the camera on the ceiling can be saved. (Third Embodiment) In the first embodiment, a plurality of cameras 26a to 26e are used, and an image signal is taken in from a camera having a high probability of showing a license plate. As shown, one camera 29 may be installed on the turntable 30 to change the shooting direction of the camera 29.

More specifically, the control computer 24 determines the shooting direction of the camera 29 based on signals from the plurality of sensors 23a to 23g, and controls the turntable control device 31 according to the determination to control the camera 29. The photographing direction is changed, and after the change, the camera 2 is changed as in the first embodiment.
Then, an image signal is taken in from No. 9 and a number recognition process is performed. When determining the shooting direction of the camera based on the signals from the plurality of sensors 23a to 23g, the shooting direction of the camera 29 and the sensor from which the vehicle detection signal is output are determined similarly to the first embodiment. Are stored in advance as a map, and the shooting direction of the camera 29 is determined using the map.

Therefore, according to this embodiment, the same effect as in the first embodiment can be obtained by one camera 29 having a narrow angle of view. (Fourth Embodiment) In the first to third embodiments, the vehicle sensors are arranged one-dimensionally to detect the position where the vehicle exists one-dimensionally. It is also possible to two-dimensionally detect the position where the vehicle is present by arranging them in a two-dimensional manner, and to take in an image of the detected position to perform a number recognition process.

FIG. 6 shows a specific configuration in this case.
The loop coils 22a to 22n are arranged two-dimensionally, and the position of the vehicle can be detected not only in the width direction but also in the front-back direction by the sensors 23a to 23n connected thereto. In addition to the cameras 26a to 26e shown in the first embodiment, cameras 26f to 26j having the same photographing direction but different focal lengths are provided. That is, the cameras 26a to 26e are focused on the front row of loop coils 22a to 22g, and the cameras 26f to 26j are focused on the rear row of loop coils 22h to 22h.
It is focused on 22n.

When the control computer 24 determines from the signals from the sensors 23a to 23n that the vehicle detection signals are output from the sensors 23a to 23g connected to the front row of loop coils 22a to 22g. In the same manner as in the first embodiment, a camera to capture an image signal from among the cameras 26a to 26e is determined, and a sensor 23h connected to the rear row of loop coils 22h to 22n is determined.
When it is determined that the vehicle detection signal is output only for the cameras ２３23n to ｎ23n, the camera to which the image signal is to be captured is determined from the cameras 26f to 26j in the same manner as described above.

Therefore, according to this embodiment, since the distance between the camera and the vehicle can also be used as information, a clear and high-quality image can be captured, and the number can be recognized more favorably. Although FIG. 6 shows a modification of the first embodiment, it can be similarly applied to the second and third embodiments. Further, in the above-described embodiment, the case where two types of cameras having different focal lengths are selectively used has been described. However, the focal length may be adjusted according to the front-back direction with respect to the traveling direction of the vehicle. . (Fifth Embodiment) In the above-described first to fourth embodiments, an example in which a vehicle is detected by a loop coil and a sensor has been described. However, as shown in FIG.
The vehicle may be detected using a to 32f.
As shown in FIG. 8, the ultrasonic sensors 32a to 32f are installed on the ceiling, and detect a vehicle passing below based on a time when a reflected wave returns using ultrasonic waves. In this case, the detection areas of the ultrasonic sensors overlap each other as shown by the dotted line in FIG.

Although the embodiment shown in FIG. 7 is shown as a modification of the first embodiment, it can be similarly applied to the second to fourth embodiments. In the various embodiments described above, the control processing of the camera and the image recognition processing in the control computer 24 are performed, but they may be performed using separate computers.

Further, the present invention is not limited to the application to a system for managing parking in a parking lot, but can also be applied to a device for recognizing a number in an automatic toll collection system on a toll road such as an expressway. it can.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment in which the present invention is applied to a system for performing parking management of a parking lot.

FIG. 2 is a diagram showing a specific configuration of a loop coil in FIG.

FIG. 3 is a flowchart showing a control process of a control computer 24 in FIG.

FIG. 4 is a configuration diagram showing a second embodiment of the present invention.

FIG. 5 is a configuration diagram showing a third embodiment of the present invention.

FIG. 6 is a configuration diagram showing a fourth embodiment of the present invention.

FIG. 7 is a configuration diagram showing a fifth embodiment of the present invention.

FIG. 8 is a diagram showing a configuration of an ultrasonic sensor in FIG. 7;

FIG. 9 is a configuration diagram of a conventional system for performing parking management of a parking lot.

[Explanation of symbols]

21: Gate, 22a to 22g: Loop coil, 23a
２３23g: sensor, 24: control computer, 25: camera selection switch box, 26a〜26e: camera,
27 management computer.

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI H04N 7/18 H04N 7/18 E

Claims (6)

[Claims] 1. Vehicle position detecting means (22a-22) for detecting a position of a vehicle in a width direction of a traversable area of the vehicle.
g, 22h-22n, 23a-23g, 23h-23
n) and a plurality of photographing means (26a to 26e) for capturing images in mutually different ranges in the width direction of the passable area.
Determining a specific photographing means from among the plurality of photographing means based on a signal from the vehicle position detecting means, and recognizing a license plate number of the vehicle based on an image captured by the decided photographing means. Means (24). 2. The vehicle according to claim 1, wherein said vehicle position detecting means includes a gate (2).
The vehicle number recognizing device according to claim 1, wherein a position of the vehicle that stops before 1) is detected, and the plurality of photographing units are installed at the gate. 3. Vehicle position detecting means (22a to 22a) for detecting a position of a vehicle in a width direction of a traversable area of the vehicle.
g, 22h-22n, 23a-23g, 23h-23
n), a photographing means (29), and an image taken by the photographing means after the change in a photographing direction of the photographing means in a width direction of the traversable area based on a signal from the vehicle position detecting means. Means (24) for recognizing the license plate number of the vehicle based on the vehicle number. 4. A vehicle position detecting means (22a-22) for detecting a position where a vehicle is present in a traversable area of the vehicle.
g, 22h-22n, 23a-23g, 23h-23
n), photographing means (26a to 26e, 29) for capturing an image of the position detected by the vehicle position detecting means, and means for recognizing the license plate number of the vehicle based on the image captured by the photographing means (24). And a vehicle number recognition device. 5. The vehicle number recognition device according to claim 4, wherein the vehicle position detecting means detects a position where the vehicle is present one-dimensionally in a width direction of the passable area. . 6. The vehicle number recognizing device according to claim 4, wherein the vehicle position detecting means detects a position where the vehicle exists two-dimensionally in the passable area.