JP2660751B2 - License plate recognition device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a license plate automatic which recognizes a license plate of a vehicle by capturing a running vehicle with a television camera, processing a still image obtained by the television camera, and processing the still image. It relates to a recognition device.

(Prior Art) Conventionally, in a bus use right arbitration device used in an arithmetic processing unit in this type of automatic license plate recognition device, the priority of each line is determined by the connection state of a bus request line, and the priority is low. When a higher-order request line is using the bus or requesting to use the bus, the right to use the bus cannot be obtained.

Only when the bus is in an unused state and no higher-level lines have issued a use request, the bus usage request for a line with a lower priority is given a use right. Was.

(Problems to be Solved by the Invention) In the above-mentioned conventional bus arbitration device, the number of requested lines is usually eight or less, but the number of lines is large, the bus use frequency is high, and the priority is low. There was a problem that the request line had to wait for a long time to obtain the right to use.

For license plate recognition, for example, character recognition of vehicle type codes and character recognition of application codes, the recognition result is not valid unless both recognitions are completed, and the priority order for each character recognition process is Absent. In such a case, due to the restriction of the bus arbitration method, the priority is made to wait, so that there is a problem that the bus access is waited for only one character recognition process, and the recognition result is delayed.

On the other hand, in license plate recognition processing, it is necessary to process all vehicles that are running continuously, so plate extraction processing and character recognition processing are pipelined, and the plate extraction processing itself is also pipelined. In this process, the candidates for the plate location position address information as the plate cutout result are sent to the character recognition process as soon as the result is obtained several times in one imaging. In most cases, the first time is the correct plate presence position address, but the extraction process is continued as long as there is time, and if there is a candidate, it is sent to the character recognition processing unit to increase the plate extraction accuracy.

For this reason, the bus arbitration system switches so as to give priority to the request line from the plate cutout process when capturing the vehicle, and to give priority to the request line from the character recognition process when the first plate location position address is obtained. If the next vehicle passes and an image of the next vehicle is taken, it is desirable that the plate cutout processing be prioritized again. However, the prior art bus arbitration device cannot perform such priority switching.

The present invention solves such a conventional problem by giving priority to the order of occurrence of bus acquisition requests, and making it possible to switch the priority between the plate cutting process and the character recognition process depending on the processing situation, thereby enabling the number to be obtained. It is an object of the present invention to provide a license plate recognition device that is optimal for a recognition process.

(Means for Solving the Problems) In order to achieve the above object, a license plate recognition device according to the present invention includes a plurality of image memory cards for storing still image digital data captured simultaneously by a plurality of cameras, and the image memory cards. A plurality of plate cutout image processing operation cards for determining whether or not an automobile license plate is present therein, and determining the plate presence position address if there is, and information on the plate presence position address Image processing calculation card for extracting the position of each character (land support code, vehicle type code, application code, serial number) from the license plate, and a plurality of character recognition calculation cards for recognizing each character from the information on each character position And an overall control card that controls and manages the entire process, and various processes for software debugging and maintenance. A processing card comprising a monitoring processing card having a monitor function capable of referring to data in the middle of processing, one bus enabling reading / writing of an image memory by each processing card, and a plate cutout image processing operation card A first bus acquisition request code output unit which receives the previous bus request signal and the current bus request signal from the input unit, and encodes and outputs the current bus request line according to an algorithm of a priority pattern stored therein; A second bus acquisition request code for receiving the previous bus request signal and the current bus request signal from the character recognition operation card, encoding the current bus request line in accordance with the priority pattern algorithm stored therein, and outputting the encoded bus request line Output unit and an internal bus request line code signal from each bus acquisition request code output unit. A bus use permission code output unit that outputs a bus use permission code signal to be used this time in accordance with a stored priority pattern algorithm, and as a bus arbiter for acquiring a bus use right, a high-speed bus use right that is optimal for number recognition processing It has an arbitration function.

(Operation) According to the above configuration, the present invention provides a bus acquisition request from each processing card at this time, a bus acquisition request from each previous processing card, and a bus use permission response to each previous processing card. By assembling the current bus use permission response most suitable for the recognition process for all patterns, it is possible to immediately output a use permission response in response to a change in the bus acquisition input. Further, since a large number of bus request inputs are internally coded, the above function can be realized with a small circuit configuration.

FIG. 1 is a circuit diagram of a high-speed bus control unit of a license plate recognition device according to an embodiment of the present invention. 1 refers to and processes a plurality of image memory cards for storing still image digital data captured simultaneously by a plurality of cameras and the memory contents of the image memory cards, and checks whether or not an automobile license plate exists in them. A plurality of plate cutout image processing calculation cards for obtaining the plate location position address, if any, and the characters (land support code / vehicle type code / use code / serial number) in the license plate from the information of the plate location position address. An image processing operation card for cutting out positions, a plurality of character recognition operation cards for recognizing each character from the information on each character position, an overall control card for controlling and managing the entire processing, and software debugging and maintenance for each. Each configured with a monitoring processing card with a monitoring function that allows you to refer to data during processing Bus request input latch unit for receiving a bus request signal from the management card, 2 is the bus grant output decoder unit for outputting a bus use permission signal to the respective processing card.

Further, 3 receives the previous bus request and the current bus request from the plate cutout image processing operation card (plate cutout unit) and codes the current bus request line in accordance with the priority pattern algorithm stored therein. First bus acquisition request code output section for converting and outputting
In response to a request from the character recognition operation card (character recognition unit), the previous bus request and the current bus request are input as described above, and the current bus request is input in accordance with the priority pattern algorithm stored therein. The second bus acquisition request code output units 5 and 6, which code and output the bus request line,
A bus acquisition request latch unit 7 for latching the request from each of the bus acquisition request code output units 3 and 4 once and storing the previous request is stored therein from all the bus acquisition request outputs. A bus use permission code output unit that finally outputs a bus acquisition permission code according to the algorithm of the priority pattern, and a bus use permission state latch unit 8 that latches the previous bus use permission state.

The outline of the operation of the control unit is as follows.
In response to the change in the bus acquisition input, the bus acquisition request code output units 3 and 4 and the bus use permission code output unit 7 determine the priority at that time, and the bus use permission output decoder unit 2 And output the result. further,
Details will be described below.

The bus request input latch unit 1 has 13 input data request signals and 14 priority mode signals. The bus request signal is composed of LWRQ which is the output of the overall control card, LWRQ2 to 7 from the plate cutout card, LWRQ8 to 12 from the character recognition card, and LWRQ13 from the monitoring processing card.

The priority mode signal is a PCORCR signal. When this signal is 0, the request from the plate cut-out card is given priority over the request from the character recognition card, and when it is 1, the reverse is true.

The output data of the bus use permission output decoder unit 2 is thirteen, that is, thirteen bus permission signals and one bus busy status signal corresponding to each request. The bus permission signal is composed of LWAV which is an input of the overall control card, LWAVs 2 to 12 which are inputs to the plate cutout / character recognition card, and LWAV 13 which is an input to the monitoring processing card.

 The priority order is as follows.

The request from the monitoring processing card (LWRQ13) is first, and the request from the overall control processing card (LWRQ1) is second.
, And thereafter follows the priority mode signal.

Requests in the plate cutout processing card (LWRQ2 to 7) and in the character recognition processing card (LWRQ8 to 12) take precedence over the first occurrence and the second occurrence, respectively. . If they occur at the same time, the priority is determined for each of the highest priority levels at that time.

Next, the algorithm of all the patterns stored in the bus acquisition request code output units 3 and 4 and the bus use permission code output unit 7 for realizing the above-described priority will be described.

Algorithm of bus acquisition request code output units 3 and 4 (1) When a is all OFF-> d = 0, o = 0 (no request) (2) When i = 0 & c = 0 When only one of them is turned on (let it be α)-→ d = Α ', oh = 0 When two of the abnormalities (α, β, γ ...) are ON, then α>β> γ ... according to the priority order of A0>A1>A2>A3>A4>A5> A6 − → D = α ′, E = β ′ Ignored after γ (3) When ≠ 0 & C = 0 When ＝= α If only one (α) is ON-→ D = α ' , E = 0 When only one of them (let β, β ≠ α) is ON-→ d =
β ', oh = 0 When two of them (α, β) are ON-→ d = α', oh =
β 'When two of them (β, γ, ββγ ・ α) are ON If β> γ according to the priority order of-→ d = β ', e =
When three or more (α, β, γ ...) of γ 'are ON When three of them (β, γ ... ≠ α) are ON (4) When a = 0 & c ≠ 0-→ d = 0, e = 0 Normally, this state does not occur.

(5) When i = 0 & u ≠ If i = α, u = β If only one of them (let γ) be ON-→ d = γ ', o = 0 Even if γ is α, β However, it does not matter if two of them (α, β) are ON-→ d = α ', o =
β 'When two out of c (β, γ ウ α) are ON-→ d = β', E = γ 'When two out of α (α, γ ≠ β) are ON-→ d = α ', E = γ' Two of them (γ, δ γ · δ are both ≠ α, β) ON
time When three or more of the a (α, β, γ ...) are ON → d =
α ', E = β' When three or more of them are ON (β, γ, δ ... α is OFF) When three or more of them are ON (α, γ, δ ... β are OFF) 3 or more of them (γ, δ ... α, β both OFF) ON
time Algorithm of the bus use permission code output unit 7 (1) When A0 = OFF, A1 = OFF, power = 0, key = 0-→ key = 0 (no request) (2) ≠ 0 (q = α ), When the requirements of A0, A1, power, and key are all different from α- → ke = 0 When α exists in the requirements of A0, A1, power, and key- → ke =
α '(3) When = 0, A12 = 0 (Plate cutout section priority) Based on the priority order of A0>A1>Power> key, if the highest priority is α, then-→ ke = α' (4) h = When 0, A12 = 1 (character recognition unit priority) Based on the priority order of A0>A1>key> key, assuming that the highest priority is α, then-→ ke = α '. The output and the internal coding correspondence are shown.

(Effects of the Invention) According to the present invention, bus arbitration control optimal for license plate recognition processing for a large number of bus input requests can be performed at high speed, and the priority of buses can be changed during recognition processing. Further, by changing the algorithm of the bus priority method, a pattern of a new algorithm can be stored to correspond to a method suitable for another system, and its practical effect is extremely large.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a high-speed bus control unit of a high-speed bus control built-in number recognition device according to an embodiment of the present invention. 1 ... Bus request input latch unit from each processing card. 2. Bus output permitting decoder for each processing card. 3. A current bus acquisition request code output section obtained from the previous and current bus acquisition requests from the plate cutout section. 4 ... A current bus acquisition request code output unit obtained from the previous and current bus acquisition requests from the character recognition unit. 5: Latch section for the previous bus acquisition request from the plate cutout section. 6 ... Last bus acquisition request latch from character recognition unit. 7 ... A current bus use permission code output unit obtained from all bus acquisition requests and the previous bus use permission state. 8 ... Last bus use permission state latch unit.

Continuation of the front page (72) Inventor Yoshiharu Yano 4-3-1 Tsunashima Higashi, Kohoku-ku, Yokohama-shi, Kanagawa Prefecture Inside Matsushita Communication Industrial Co., Ltd. (56) References JP-A-62-90800 (JP, A) JP-A Sho 60-221863 (JP, A) JP-A-3-51999 (JP, A)

Claims (1)

(57) [Claims] 1. A plurality of image memory sections for storing digital still image data picked up by a plurality of cameras simultaneously, and referring to and processing the memory contents of the image memory sections to determine whether an automobile license plate exists therein. A plurality of plate cut-out image processing operation units for checking and, if present, the plate location position address, and each character in the license plate (land support code / vehicle type code / use code / serial number) from the information of the plate location position address ), An image processing operation unit for cutting out the position, a plurality of character recognition operation units for recognizing each character from the information on each character position, an overall control unit for controlling and managing the entire processing, and a software debug and maintenance unit. A processing unit comprising a monitoring processing unit having a monitor function capable of referring to data in the middle of each processing; A bus enabling read / write to an image memory by the unit, a prior bus request signal and a current bus request signal from the plate cutout image processing operation unit, and a priority pattern stored therein. A first bus acquisition request code output unit for encoding and outputting the current bus request line according to the algorithm described in (1), and receiving the previous bus request signal and the current bus request signal from the character recognition calculation unit as input and storing them internally A second bus acquisition request code output unit that encodes and outputs the current bus request line according to the algorithm of the priority pattern that has been set; and internally based on a bus request line code signal from each of the bus acquisition request code output units. Uses the bus that outputs the bus acquisition permission code signal to be used this time according to the stored priority pattern algorithm Number plate recognition system, characterized in that it and a variable code output section.